AgroGea - Nutrition and growth of suckling pigs by providing creep-feeding supplements

Introduction

This research project involves a literature review of different topics related to the nutrition and growth of the suckling piglet. The nutritional analysis of feeds and feeding methods at this early age is not an innovative idea, however, research reports have not been compiled in the USA. British and Australian swine nutrition researchers have published a majority of the research related to trials using supplements containing highly digestible proteins for suckling pigs, and they have identified metabolic and physiological factors that contribute to the survival and growth of the nursing piglet from birth to weaning. Most of the byproducts used for baby pigs are regionalized. For example, USA nutritionists use plasma proteins. On the other hand nutritionists in the United Kingdom prefer cooked cereals and skimmed milk powders, and most countries in Europe use whey proteins and fishmeal. Other countries worldwide tend to use imported goods or soybean meal and fishmeal. The important consideration is that pork producers attempt to select the best feedstuffs and apply them in economical quantities to advance the science of feeding and providing for the well-being of baby pigs.

This article attempts to incorporate the best scientific principles applying selected published results for supplementing suckling piglets to enhance weaning weight, and disseminate practical methods that can be applied to all kinds and sizes of hog production systems. Experienced nutritionists are the primary researchers who have extrapolated nutrient requirements from weaning starting diets to the less mature digestive system of the suckling piglet, thus their recommendations are not over imposed in this paper. An understanding of this complex phase requires knowledge in multiple fields such as agronomy, swine nutrition, stockmanship, farm management, veterinary medicine, feed industrial processing, storage, physiology, biochemistry, and other disciplines related to the pork industry. The information in this article is geared toward helping pork producers and swine nutritionists resolve some of the issues related to using sow milk supplements or milk substitutes, such as potential feeds available in the marketplace as well as home made food for neonatal piglets. Some of these products may still be under development and test screening. These feedstuffs are introduced in the following pages. In this global economic era, it is important to recognize other feeding methods and feed manipulation that may enhance the well being and development of the animal during the pre-weaning and post-weaning stages as important and critical periods in the development of the pig. This paper is an effort to elucidate practical ideas and feed resources for the hog farm system and specifically address the needs of the neonatal piglet before weaning. This article may contribute to the adoption of new technology and provide information for nutritionists for accurate decision making of the best supplements and diets available in the market or under development for further years to come.

The Journal of Animal Science contains extensive published results that are useful for pig nursery systems. This Journal contains most of the related publications from U.S. researchers in monogastric nutrition, yet many articles are from abroad. This compiled information may assist those involved in swine-related fields by providing nutrient densities of rations in the post-weaning phase to meet pre-weaning nutrient requirements of the piglet.

There is a paucity of objective data available in a compiled format to help producers decide whether an expensive feedstuff is a good nutritional source to improve the welfare of the piglet and sow. There are many external factors involved in the successful use of a particular feed that are not dependent upon the feed itself, nevertheless it is important to know such factors as palatability and digestibility to enhance feed consumption. This research will provide a giant step toward presenting the best alternative choices.

In summary, the scientific knowledge of nutrition using the art of feeds and feeding experiences may contribute to the physiological development and growth rates of the neonate pig. It may reduce morbidity and mortality at this early age of the life cycle of the pig, especially having low birth weights of less than two pounds, yet have good viability to reach market weight. The overall supplementation to the piglets’ diet may ultimately improve reproductive performance of the sow, to reach better efficiency and performance goals in the productive system, and the pig to reach market weight efficiently, which contribute to the overall revenue of the farm. The ultimate decision for the pork producer is to be competitive at home and in the global market.

Background Information

Supplementing a suckling pig during the lactation period (before weaning) was a common husbandry practice during the early 1970s. The lactation period lasted for 42 to 56 days wherein the sow did not have enough milk production and sufficient body reserves to sustain the fast growing demand of her piglets. During this time newborn piglets may have had vitamin deficiencies for choline, folic acid and complex B vitamins, and sows did not have all full functional milking teats at the end of the lactation period. It was common to observe dams with broken legs when being relocated from farrowing pens at weaning time because of calcium and phosphorous depletion from their bone reserves. Some premixes with vitamins and minerals were not as complete as necessary for the nutritional requirements for these rotational crossed breeders (e.g., Yorkshire, Landrace, Duroc, Hampshire). Managers of confinement hog farms noticed at weaning time, exhausted sows and gilts with depletion of muscle and fat tissues caused by the extended lactation period. During these years, the practice of providing an extended lactation period generated several research studies and publications to alleviate this lag in the production system. However, many studies did not lead to improved practice in the field. The need was identified well by nutritionists and stockpersons, but the feed industry did not provide enough available feedstuffs with good quality and digestible byproducts for suckling piglets, thus it was a great restriction for the implementation and establishment of creep feeding management practices in the first confinement hog barns during these years.

In the 1980s, the hog industry turned to rapid growth and use of vegetable byproducts from the oil seed industry, confinement of modern facilities, breed improvement and selection, and intensive production systems that generated a more skillful, technically and scientific way of rearing animals. It was a matter of economic efficiency and space turnover more than the old ways of pork production. The industry changed with the development of rearing and feeding techniques for Specific Pathogen Free (SPF), Minimum Disease (MD), Segregated Early Weaning SEW), Medicated Early Weaning (MEW) and other piglet rearing methods. During this time piglet nutrition research practices focused on feeding methods for post weaning pigs but not on creep feeding or use of other supplementation practices for lactating piglet.

Lactation periods lasted for up to 35 days in the 1980s. The search for the best lactation length was not defined, therefore tests were carried out for 0, 7, 10, 14, 18, 21, 28 and 35 lactating days to determine the best economical profit and practical management. The irregular availability and quality of sow’s milk substitutes and competitive prices from suppliers were important factors for the slow adoption of providing creep feed supplements for suckling piglets. The general thought on farms was that there was not enough time for supplementing suckling piglets. The hog unit manager (integrated system) already had in mind that he had the best selected milking mother and had prepared the ideal environmental conditions to receive the fastest growing animal. In addition, after some fostering practices, it was perceived that the piglets could grow faster later on during the nursery facility and obtain a compensating growth factor. There was no need for an early rush if the animal could catch up in weight later, in the finishing stage.

With a short lactation lapse, modern facilities were looking for better weaned pig starting diets, feed particle size, pellet presentation and extrusion, use of growth promoters, including artificial amino acids to meet nutritional requirements, more liable vitamins and digestible mineral sources, and testing probiotics. Other external aspects of the nutrition system were related to the management of the feed, focused on how to reduce transportation feed segregation and minimizing storage spoilage or mycotoxin growth. Other investment projects were the modernization of the farm for environmental controlled farrow and nursery barns, replacement of crates and pen designs, use of computerized software, genetic selection of new breeders, artificial insemination programs, boar centers, sanitation and health controls methods, disease eradication, and meat quality control to supply market demands. These changes transformed and shaped modern pork production farming.

New technological pig farms were changing rapidly but little attention was paid to methods of supplementation of the suckling piglet and appropriate feedstuffs for this early age. During this time, improving this obsolete practice was not considered because it represented an increase in labor demands and a tremendous risk for other diseases and diarrhea. There were too many other demands inside and outside of the production site, than considering the care of the youngest pigs. Pork producer had genetic support from their selected sows to provide enough milk for piglets, a good mothering instinct, resilience to reduce crushing, and excellent farrowing rates.

During the 1990s, the agro-industry improved the quality of many feedstuffs already existing in the market and developed new byproducts that had great potential in both human food and the feed animal industry. At this time the pork industry moved from family production farms to large corporate production facilities. This changed the decision making of many activities in the farm, with large purchasing capacities and computer economic analysis rather than a direct stockperson involved in daily decision making. There were two types of farms, those that maintained short lactations periods of 10-19 days with improved growth rates of weaned pigs and farms with longer lactation periods of 21-28 days that had better reproductive performances and slow growth rates in piglets.

However, both productive systems involved determining the best economic methods for profitability in this competitive market. Genetic selection for large litter size and short lactation periods did not resolved the litter size at weaning and the low numbers entirely continued to the nursery stages with all the disadvantages of a physiologically immature early weaned piglet. The profitability of the farm did not improve greatly with the advent of new breeds and early weaning practices. The number of pigs per sow per year did not increase considerably and All-In-All-Out systems for early weaning did not work as predicted. During this time, decision making focused on gross important aspects rather than details. The final days of this period fixed lactation length between 18-24 days which represented small lactation weight gains for this growing stage compared with the genetic potential of the lean pig.

During the early 21^st century the pig market depends more on international demand and world market competition. However, large production systems have been restricted in many countries due to environmental policies and regulations. The trend toward more natural pig behavior has been appeased by new regulations for space allowances in the United Kingdom, antibiotic feed additives restrictions in Sweden, and cage farrowing facilities in the state of Florida USA. These factors have started to change the outlook of the pig industry worldwide toward more sustainable methods to produce meat products. Nowadays, to be competitive and profitable with high quality products, the pork industry must use all the available factors to reach its goals while avoiding misuse of the technological opportunities on hand. Several general factors influence the production of pork meat: nutrition, husbandry, management, housing, personnel training, genetics and marketing. All of the factors contribute toward reaching one goal: to produce the best quality meat with economic efficiency, while being politically acceptable and environmentally friendly.

Rationale and Purpose

Irregardless of the biological or economic importance of any stage in the life cycle of the pig, the suckling period is the shortest of all the productive stages. However, it may be the ignition step for the following growing periods and the definition of the muscular cell numbers that influence growth rate and, later on, the reproductive performance and quality of the selected gilt. Thus, the importance of applying analysis of the nutritional supplements for suckling piglets and using the best management practices for feed enable farms to reach their desired economic goals.

Despite numerous available publications with remarkable scientific efforts explaining the importance of metabolic nutrients for the pre weaning pig, their applied level may be far from reality. Research results should not only be for the sake of new knowledge or to understand the stimulus of the feed to the genes’ actions or how an element affects the mitochondria of the cell. The technology in this area is advanced but to explain the effect of 50 nutrient components in the feedstuff in 30 thousand different genes in the body of a pig, it is a very large matrix that does not have an end. This is a process of two routes, one for scientific basic knowledge and other way for applied pork industry needs. For practical reasons, it is more important to identify the advantages and disadvantages of viable feedstuffs converging nutritional requirements for creep feeding (highly palatable and digestible diet during suckling) as supplements for the lactating piglet during its short neonatal period. “Science should be as simple as possible but not simpler,” according to Albert Einstein.

The comparative nutritional analysis values of supplements to sow’s milk substitutes for the survival and growth performance of the suckling pig have their own limitations. Dry creep feeding and liquid feed have different feed consumption rates, thus underestimation or overestimation of nutritional requirements established for this early age during lactation is present in these analyses which have not been appropriately defined. The National Research Council (NRC 1998) Nutrient Requirements of Swine reported values for 1-5 kg body weight (BW) piglet (104). A dry feed diet with high levels of protein may increment the severity of diarrhea but, under low consumption, increased dry matter intake. A high protein diet enhances immunoglobulin synthesis and reduces the need of a second reinforcement Iron shot. The amino acid composition of the ideal protein is yet to be determined and may be related to only a few essential amino acids. This may reduce the protein content of the diet and reduce scours problems.

Only a few research articles report the digestibility of raw feed materials for neonatal pigs. In addition, there are a few Extension bulletins for nutrient requirements of baby pigs, such as the ISU cycle of the pig (176). This is another reason why the feeding practice of creep feeding has not been adopted in the general production system. However, there is technical and scientific evidence that it should be a common management practice in farms worldwide, irregardless of their size, geographic site, and technological development of the production systems.

The main purpose of this paper is to provide an overview topic of the suckling piglet nutrition presenting the most relevant and recent published information on baby pig creep feeding and supplementation. There is a shortage of practical information, thus the primary objective of the study is provide a review of the information currently available for the swine nutritionist, stockperson, manager, and the pork producer, internationally, on the methods of feeds and feeding of the suckling piglet. This may contribute to enhance the decision-making ability in farms. The research will also enable those involved in the pork industry to evaluate the importance of current practices and apply the available techniques within current established management programs.

Piglet Colostrum and Milk Intake

Unlike other ungulates, the sow does not lick its newly born piglets or offer them assistance in finding the udders. Some sows will stand several times and sniff their piglets during farrowing (26). This behavior increases the chances for overlaid piglets and, by genetic selection, they may overcome this genetic trait, especially as some breeds have better maternal characteristics than others. The reduction of feed intake 3 days before farrowing induces glucogenesis from fat tissue and stimulates feed intake after delivery.

After birth the piglet will try to find the udder and suck on a teat a soon as possible (<30 minutes), and typically will move along sucking several other different nipples in succession, from 2-13 teats in the first 8 hours (20). These are general considerations that prevail during the first hours of lactation. Competition at the udder affects mortality in smaller piglets of the litter and results in poor growth for many of the survivors. Cross fostering is necessary only when the piglets exceed the number of teats. Split-weaning (SW) is used to achieve a more uniform litter but it does not improve physical conditions for weaning.

The termination of colostrum synthesis occurs 1 hour after the sow releases the placenta, with colostrum ejection every 10-20 minutes. Piglets often consume 5-7% of their body weight in colostrum in the first hour of suckling. The suckling range is 20-92 minutes throughout the day and night, but there is a daylight behavior pattern for most farrowings. An estimation of colostrum and milk intake for the first 2 hours after birth is about 113 grams with consumption of 10-60 g of colostrum per suckling (19). The first day the piglet consumes 280 g/kg body weight (BW)/day of colostrum, but is physically able to consume from 290 to 490 grams per day (2).

When the piglet has sucked all the colostrum from the teat an autocrine mechanism and the withdrawal of progesterone will release synthesis and secretion of milk which reduces the secretion of colostrum. This ensures that, with an extended farrowing period, the last-born piglet obtains colostrum of the same composition and protective capacity as the first-born. The milk ejection reflex of the sow is under tight control, with milk only available to the piglets during a “let-down”, which lasts for about 15-20 seconds per lactation. This control, primarily as a result of oxytocin release, ensures that a dominant piglet does not deprive others of milk. This process maximizes the survival of feral pigs and may be applicable to domestic pigs but not for cows. However, this strategy limits the amount of milk that can be removed by the piglets during suckling, and also limits milk consumption and growth (94).

If 7-day-old piglets ingest 100, 200 or 300 g of milk intake/kg BW/day their whole body protein synthesis will be 10.7, 16.9 and 20.9 g/d/BW^0.75, respectively, and their protein deposition will be 4.5, 14.6 and 19.7 g/d/BW^0.75(82). The more milk consumed, the better the growth rate. Litters of 4 piglets that suckled 1 kg of sow’s milk/pig/day, and milk consumption were 0.7 kg/pig/day in litters of 12 piglets. A litter of 6 pigs may consume 1.3 kg/pig/day, and 0.90 kg/pig/day in litters of 14 (97). There is evidence of piglets consuming 460 g/kg BW in the first 27 hours of life; a sow with a litter of 10 pigs must start producing > 6.4 kg/day of colostum. During the second half of the suckling period, after 7 days of farrowing, the demand is 800-1100 grams of milk/pig/day and at 21 days after birth (at weaning time) the sow’s lactation curve should reach > 20 kg milk/day to supply the energy requirements of 10 pigs per litter (2). A large litter size of >10 pigs will ingest about 10-12 kg of milk per day (97). After the peak of lactation and a plateau period, the milk production slope will eventually decrease even in sows with the highest feed consumption rates (155).

The suckling pig depends on its mother’s milk production for growth and to express its genetic growth potential. If the sow does not achieve genetic milk yield potential either the heaviest piglets in the litter that choose the most productive teats from the dam will reach potential growth. The stronger piglets will retain more teats at the expense of the smaller pigs, and there are many physiological, behavioral and external conditions that will affect complete genetic milk production capacity (167).

Piglets that select the best teats before 3 days of age will remain more dependent on milk and less interested in solid feed (12). In general, a piglet of this age will partition feed nutrients into adipose tissue instead of the more desired economical lean protein muscle accretion; most of the increased protein weight will be on the accelerated growth of the digestive organs. The ingestion of colostrum after birth for 36 hour greatly stimulates growth of all gastrointestinal organs and particularly the small intestine. The leaner Pietrain breeds require more concentrated feed to grow to their genetic potential because their smaller intestinal size reduces its gut capacity to consume feeds. For leaner breeds in general, this early intestinal growth follows a genetic pattern for survivability but it is not a genetic trait that will influence its final lean to fat market ratio.

The gene expression of this early age is not a determinant of the final quality of the end product for meat or reproductive replacement. Appetite and thirst will be satisfied by the sow’s milk production but, in many circumstances, the environmental conditions will not enable them to reach their dam’s milk potential. The desired piglet goal to reach their genetic growth capacity will not be expressed after birth due to the low energy level concentration of the milk colostrum and the small milk production at the beginning of the suckling stimulus. In other instances the sow may be a great milk producer and, if she had farrowed a small litter, the piglet will be constrained by the limitations of its gut capacity and suckling ability. Many internal and external factors are involved in less expression of their genetic potential for the maximum milk production, maximum milk suckling capacity, and maximum growth and survivability (169).

Colostrum metabolism and fat accretion

After suckling, the piglet increases glucose and galactose levels in the plasma from gluconeogenesis of fat-glycerol, lactose, and small contributions of amino acids (62). The levels of lipase from the pancreas are low, but colostrum fat is very digestible because milk provides adequate amounts of carnitine, a substrate required for fat transduction. This enables the liver to oxidize fatty acids. While the new born piglet is very lean and possesses only 10 to 20 g/kg body weight as fat, it increases to 150 to 200 g/kg body fat by 18-21 days of age (62, 66). The body energy reserves are less than 2% body fat content and total body glycogen stores (liver and skeletal muscle) are < 38 g/kg BW. Liver glycogenolysis is active and can utilize 70% of the available glycogen immediately after birth to release blood requirements for glucose. Glucose utilization in neonate piglets is 10g/kg/day (62). Body fat reserves are mobilized at a lower rate and both will be depleted in 24h if the piglet does not consume colostrum. The newborn piglet requires > 14 g/kg BW/d of glucose that must be supplied: 20% from body glycogen, 35% from milk lactose, and 55% from milk fat (16).

Supplementing Baby Pigs

A 20-day-old piglet with 4-5 kg body weight can suck 345 g of milk/day/kg BW in natural milking and when fed in a bottle can consume 490 g of milk/day/kg BW. Piglets consume 24% more feed in artificial rearing at days 4 to 28 of age and had growth rates 30% higher than only sow-milked pigs (41). This may be a combined factor in a sow’s low milk capacity or lack of a piglet’s strength to suck. Creep feeding may be beneficial for small piglets or litters with low milk producing sows if the milk replacer is also supplemented after weaning (82). Supplementing the same creep feed after weaning ensures feed consumption for palatability, enzymatic adaptation for the substrate already developing, and reduces post-weaning syndrome and lag stress.

The heaviest pig may consume more than 100 ml of colostrum in the first hour of life whereas the smallest may not ingest colostrum at all. The oral supplementation of the smaller piglets with cow’s colostrum or spray dried blood with immunoglobulin 3 days after birth does not have consistent results; the endocyte closure time of the intestine was not considered in these studies (61). The intestine pinocytosis action has the capacity to absorb colostrum antibodies before intestinal closure at 18 to 36 h of life. Enterocyte cell maturation is completed at 19 days of age, and these mature cells are more capable for digestion (156). Newborn pigs that have fasted respond to an intra-gastric administration of fat, which increases their gluconeogenesis levels and synthesis of glucose (62). This can be a measure to reduce starvation of the neonates.

Feed Intake and Milk Production in Sows

The sow has physical limitations to consume large amounts of feed per day in order to produce more milk. On the contrary the dam is capable of digesting large amounts of feed concentrate, increasing the ingestion of dry matter and protein per day. The sow has the metabolic potential to synthesize 23 kg of milk per day (175). This metabolic potential is impaired by hormonal changes after parturition, the process of uterus involution and protein accretion to regenerate reproductive tissue and low piglet stimulation level at suckling the udder for time expended in fighting, resting or weakness. Transgenic gilts with bovine a-lactalbumin production may increase milk production but time will reveal further results (115). The nutrient content in 7 kg of lactation feed can synthesize 10 kg of milk and this conversion factor produces a shortage of milk supply (41). The lactating sow may need more concentrated diet than the NRC 1998 specifications. Litters of 12 piglets could increase 50.7 kilos of body weight gain in 20 days if the sows are producing milk of 2.9-3.7% protein content. After farrowing, the sows should be fed three times a day and gradually increase feed portions at the rate of feed acceptance and intake. A daily feed rate of controlled quantities will reduce feed spoilage and the likelihood of constipation. This digestive disorder requires higher levels of manganese or other laxative salt or fibrous feed to alleviate this symptom.

Only for high milking sows and large litters (10 piglets), supplementing the sows’ diet with fat, lysine and valine will produce more milk and a positive effect on the weaned weight per litter (95, 125). Excess of valine in the udder cells will be metabolized for energy but will not spare other energy source. Under other conditions increments of the valine content of the lactation feed would not have positive response (155). Sows during 21 days lactating period who received 5.85 kg diet/day with increased valine levels to 1.20% while maintaining the other amino acid levels recommended by the NRC, produced litters with 3 more kilos of weaning weight (61.6 vs. 65.0 kg/litter). The valine content was metabolized in the mammary gland to produce energy in the udder that increased milk urea N (122).

The number of piglets in a litter is determinant for the physiological udder stimulus for milk production level. For 3-4 pigs/litters the expected milk yield would be 4 kg/day. For litters with 5, 6, and 7 pigs, the milk production per litter increases to 5 kg/d. Sows lactating 8,9,10 or 11 piglets produce 8.3 kg of milk/day, whereas for litters with 12 and 13 pigs the sow will produce 9.8 kg of milk per day (126, 134).

Equations for estimating milk production from various authors are as follows:

Milk Yield production = 0.581 Litter Size + 1.81.

MY= 0.796 LS + 2.

MY= 0.689 LS + 5.98. (41, 97).

Another model to predict milk yield production is:

Milk (kg) = (2.50 X ADG) + (80.2 X piglet BW) + 7. Where Y=0.9468x + 0.3888 with a R²=0.8959 for the prediction line and a Y=0.9848x with and R²+0.8944 from the observed data (124).

The determination of milk production to estimate nutrient requirements of lactating sows is represented by the following equation (25):

DM= 0.60 X ADG + 31.7 Eg – 62

E = 4.09 X ADG + 230 Eg – 485

N = 0.027 X ADG + 1.12 Ng – 2.59 ; Where:

Dry Matter (DM) and Nitrogen (N) are in grams/piglet/day;

Energy (E) in kcal/piglet/day;

Average Daily Gain (ADG) in grams/piglet;

Energy in Piglet Weight Gain (Eg) in kcal/gram; and

Nitrogen in Piglet Weight Gain (Ng) in %.

These prediction equations are over 12 liters of milk/day. This is a high metabolic response of the sow because during lactation the animal loses more than 23 kilos of live weight and 8.8 mm back fat over 28 days of lactation, even when consuming more than 5 kilos of feed per day (97). Increasing feed consumption during lactation maintains sow condition scores and increases milk production and piglet growth rate (Table 1.1) (101).

There are different contradictive published results for the curve of lactation in sows that are presented to compare these reports. The peak of lactation is at 10-14 days after farrowing, and it is only sufficient for pigs to attain about 50% of their growth potential (54). Other authors noted that the peak of a sow’s milk production is at 14 to 21 days post farrowing (99). There are genotypic differences among dams and the speed growth rate of a litter pig’s demand for more milk (155). The growth rate of suckling baby pigs is reduced after 8 days on lactation (117). This indicates a shortage in milk production to respond to the growth rate of a fast growing pig.

Table 1.1. Effect of dietary energy intake on sow’s body weight, milk yield and piglet growth during lactation (101)

	Dietary energy intake (MJ DE/d)
	38.00	46.90	56.00	62.10	69.10	77.90
Back fat loss (mm)	9.8	7.7	7.1	8.1	5.8	6.5
Live-weight loss (kg)	30.9	24.0	17.5	18.8	12.0	5.0
Piglet growth (g/d)	215	227	237	254	249	267
Milk yield (kg/d)	9.18	8.91	9.80	10.25	9.95	11.45
N metabolism (g/d)
Milk	83.7	81.9	78.3	90.8	86.5	102.9
Balance	-25.4	-14.3	4.5	7.8	19.3	21.7

Under different circumstances based on breed, nutrition, environment and management, lactation is at its maximum at 3 to 4 weeks (94). Then milk production sharply declines at about 30 days after delivery (51). There are differences in the peak length of maximum milk production, but all agree on a quadratic curve of increase, a plateau phase and posterior reduction yields of milk production.

Feeding the sow during gestation with extra feed or fat had disappointing results. It did not increase body energy storage in fetal and newborn pigs. The transportation of fatty acids across the placenta was negligible (62). In the occurrence of a positive response after delivery, the milk produced by the sow had more fat content which spared some glycogen in the blood of the piglet and somehow resulted in a more viable neonate pig (19). However, feeding gestating sows with 1, 3 butanediol increased glycogen activity in the liver of the fetus but increased only small amounts of fetal fat reserve (62).

Colostrum and Milk Composition

The release of immunoglobulins (IgG1, IgG2, IgM, IgA) provide antibody protection for the newborn piglet. Other proteins that function as antibodies, cellular elements such as polymorphs and low proportion of macrophages and g-globulins in the milk colostrums also have protective effect. The sow’s milk has higher levels for IgG1 than the other immunoglobulin factors (Table 1.2). There is experimental evidence that stressed sows during gestation do not reduce IgG concentration in the milk. The fetal piglet may receive maternal stress hormones as a flux of corticotrophin (ACTH) causing a reduction in the permeability of the neonatal gut to antibodies. This impairs humoral and cellular immune functions in the suckling pig. The neonates develop their own immunoglobulin synthesis of (IgD and IgE) at an earlier time if colostrum has fewer protective antibodies or if they are passively transmitted in a low rate (139). The antibodies are gamma shaped protein molecules produced in b cells as a primary immune defense. During this adjusting period the piglet is more exposed to diseases while developing synthesis of the immune system. This physiological process increases the risk of diseases. The suckling pig begins synthesizing IgG from 7 days of age but this amount is correlated with the amount absorbed from colostrum (148).

Table 1.2. The protein content of sow’s colostrum and mature milk (22)

	Colostrum¹	Mature milk²
Total protein (g/100 g milk)	15.14	5.47
Casein (g/100 g milk)	1.48	2.74
Whey (g/100 g milk)	14.75	2.22
Serum albumin (mg/ml milk)	15.79	4.61
IgG	95.60	0.90
IgA	21.20	5.30
IgM	9.10	1.40
Lactoferrin (mg/ml milk)	1,200	<100

¹Taken immediately postpartum.

²Classified as milk samples collected between 14 and 21 days postpartum.

These groups of ingested immunoglobulin proteins are absorbed intact and not digested, enhanced by the presence of protease inhibitors already present in colostrum (149). The levels of these maternally derived antibodies are highest at day 1 post-farrowing and then decline to very low levels by the time the pig reaches 3 weeks of age but they will be followed by a transient production of milk immunoglobulin IgA to maintain protection (8).

Sow milk composition changes with the stage of lactation and feed manipulation (155). Total solids, protein, minerals, fat and lactose content result in considerable change but the amino acid build up of the protein will be more stable (Table 1.3 and 1.4).

The presence of free amino acid in milk composition results in a more digestible and efficiently absorbed product (Table 1.5). In whole milk, amino acids found in abundance in whey proteins are cystine, glycine, and threonine which are less digestible than proteins from casein as glutamic acid, proline, and methionine (118). Thus the CP factor 6.38 for nitrogen.

Porcine colostrum may contain 151 g/kg of protein and is lower in ash content, which is the opposite of that found in many other species (Table 1.6). The liquid form of milk limits protein concentration and its quantity is not a major factor for survival (62). Amino acids participate more on the metabolic energy requirements of the suckling piglet rather than on protein accretion, which is a controversial economic situation when supplementing piglets.

Table 1.3. Average composition (g/kg) of sow colostrum and milk (8, 118)

Variable	Colostrum	Milk
Dry matter	215	187
Crude protein (N X 6.38)	105	54
Fat	54	71
Lactose	38	54
Gross energy (MJ/kg)	5.4	5.0
Ash (21)	7	9
Essential amino acid (g/16 g N)
Lysine	7.32	7.33
Methionine+cystine	3.24	3.30
Tryptophan	1.86	1.24
Threonine	5.46	4.52
Leucine	9.81	-
Isoleucine	3.87	3.98
Valine	5.95	5.25
Histidine	3.17	3.23
Phenylalanine	4.56	4.09
Tyrosine	5.63	4.26

Table 1.4. Porcine colostrums, milk nitrogen, and amino acid composition (37)

Variable	Colostrum	Colostrum	Milk	Milk
Protein (g/L)		87-155		29-55
Urea (mmol/L)		6.04		5.18
Ammonia (mmol/L)		2.01		1.25
Amino acids	Free*	Protein Bound**	Free*	Protein Bound**
Arginine	25	23-50	63	6-15
Histidine	1,023	14-33	538	4-12
Isoleucine	37	26-42	17	9-15
Leucine	85	65-120	38	20-34
Valine	64	50-81	111	12-20
Lysine	30	45-77	58	19-26
Threonine	40	40-88	364	10-20
Methionine		12-15	21	4-7
Phenylalanine	36	23-43	33	7-13
Proline	50	47-142	115	26-37
Tyrosine	34	25-52	63	8-15
Cystine	24	11-13	218	2-3
Glutamine	108		1,929
Glutamate	150	78-107	905	35-56
Alanine	132	42-83	659	12-22
Aspartate	38	51-108	472	15-30
Asparagine			201
Glycine	159	33-82	1,358	8-24
Serine	30	49-103	376	13-26
Citrulline			46
Ornithine	43		55
Taurine	903		1,488

*Free, mmol/L: **Protein bound, mmol/L. Glutamic acid, Aspartic acid.

Table 1.5. Porcine colostrum and milk inorganic element composition (mg/L) (37)

Variable	Colostrum	Milk
Calcium	900-1519	1511-2274
Phosphorus	900-1579	1041-1832
Magnesium	80-120	80-133
Potassium	1250-1617	356-1000
Sodium	758-820	340-542
Chloride	1200	1000
Iron	2.29-4.68	1.33-4.60
Zinc	9.2-15.98	4.94-7.35
Copper	2.86-3.21	1.11-2.01
Manganese	0.12-0.45	0.06-0.38
Selenium	0.10-0.15	0.02-0.03
Chromium	0.60	0.46
Aluminum	3.5	1.8-3.7
Nickel	0.42	0.31
Lead	0.17	0.16
Cadmium	0.04	0.04
Boron	0.03	3.45
Sulfur		36.1
Molybdenum	0.04	0.02-0.10

Table 1.6. Composition of mammalian milks at mid-lactation (60)

Species	Protein (g/l)	Fat (g/l)	Carbohydrate (g/l)
Woman	8	41	68
Cow	32	37	46
Sow	56	83	50

The protein concentration of sow’s milk does not have an effect for maximum growth rate in suckling pigs. Caseins are nutritional proteins made of amino acids. They are carriers of calcium and may promote non-pathogenic bacteria growth. b-casomorphin and a-casein from casein protein may provide immunologic activity while the whey proteins are protective proteins made of blood serum albumin, a-lactalbumin, b-lactoglobulin, IgG, IgA, IgM, lactoferrin, and other minor proteins such lysozyme, transferrin, Vit. B12-binding protein and the bifidus factor. These whey proteins molecules are absorbed by endocitosis mode of action during the first 1-2 days as explained above.

During the intestine maturation some immunoglobulin molecules will be digested because a-lacatalbumin protein is made of high levels of lysine, cysteine and tryptophan with high digestibility and biological value. The resistance to digestion of IgG is more notorious in the proximal part of the intestine with only 50.7% of the protein molecule being digested and when it passed to the medial part of the gut an additional 47.1% digestion occurs for this IgG protein, upon reaching the terminal part of the intestine the protein molecule had an undigested percentage of 10.1%. In the caecum it was almost fully digested with a remainder of 0.9%; and in the colon was 0.1 %, almost completed digested (100). Under other circumstances, there are some contributions in the amino acid profile of the colostrum composition as immunoglobulins being glucoproteins, but they are not hydrolyzed so they are not digested (22). This protein functions as biding agents for the toxins from bacteria.

The fat content in colostrum varies consistently, from 5% at farrowing time to its highest level of 10% at 72 hours post partum. Afterward, it declines during lactation to an 8% fat content and even lower and its dependent of the caloric density of the diet and feed intake. The composition of milk dry matter content of fat is 400 g/kg during late lactation (Table 1.7 and 1.8). This is direct effect of body fat contribution to the synthesis of milk fatty acids.

Through these tables it is evident that colostrum and milk undergo constant changes during lactation and its composition is highly correlated to metabolic rate, milk synthesis and feed nutrient intake. However, protein composition and microminerals are less manipulated by external factors.

Table 1.7. Chemical composition of sow colostrum and milk (22,37)

	Colostrum
Variable	During Parturition	24 h after parturition	Milk at 15 days
Dry matter (%)	23.40	22.00	19.20
C. P. (Nx6.38) (%)	13.10	9.10	5.50
Fat (%)	5.10	6.80	8.10
Lactose (%)	3.80	3.90	4.80
Energy (kJ/g)	5.93	5.89	5.23
Amino acids (g/16g N)
Arginine	5.53	5.80	6.50
Histidine	2.97	2.99	2.78
Isoleucine	3.77	3.98	3.71
Leucine	9.85	9.40	8.36
Lysine	7.34	7.43	7.42
Methionine+cystine	3.40	3.02	3.34
Phenylalanine	4.49	4.29	4.08
Threonine	5.90	5.10	5.03
Valine	6.45	6.04	5.68
Fatty acids (% total FA)
C14:0	1.90	1.80	3.40
C16:0	23.50	22.50	38.70
C16:1	4.70	5.20	10.70
C18:0	5.30	5.80	5.50
C18:1	38.70	42.80	23.20
C18:2	20.20	16.90	13.10
C18:3	1.60	1.30	1.10
C20:0	0.20	0.10	0.20
C20:1	0.50	0.50	0.20
C20:2	0.50	0.50	0.20
C20:3	0.30	0.20	0.10
C20:4	1.10	0.90	0.60
Elements
Ca (%)	0.066	0.103	0.146
P (%)	0.110	0.127	0.117
Mg (%)	0.007	0.009	0.008
K (%)	0.119	0.143	0.083
Na (%)	0.082	0.048	0.043
Cu (mg/g)	3.21	2.46	1.79
Zn (mg/g)	14.00	8.31	5.88
Mn (mg/g)	0.12	0.11	0.06
Fe (mg/g)	4.68	3.52	2.88

Table 1.8. Fatty acids (%) in the fat of sow’s colostrum and milk (22, 37)

Fatty acid	Colostrum	Mature milk
Butyric Acid (C4:0)	0	0.08
Caproic Acid (C6:0)	0	0.09
Caprylic Acid (C8:0)	0	0.03
Capric Acid (C10:0)	0	0.01
Lauric Acid (C12:0)	0	0.02
Myristic Acid (C14:0)	3.20	3.71
Myristoleic Acid (C14:1)	0.01	0
Pentadecanoic Acid (C15:0)	0.03	0.01
Pentadecenoic Acid (C15:1)	0.01	0
Palmitic Acid (C16:0)	33.30	37.00
Palmitoleic Acid (C16:1)	5.47	9.10
Heptadecanoic Acid (C17:0)	0.08	0.09
Heptadecenoic Acid (C17:1)	0.13	0.14
Stearic Acid (C18:0)	6.31	6.02
Oleic Acid (C18:1)	37.50	33.00
Linoleic Acid ((C18:2)	12.70	8.90
Linolenic Acid (C18:3)	0.74	1.14
Arachidonic Acid (C20:4)	0.42	0.51
Behenic Acid (C22:0)	0.01	0.01
Eicosatric Acid (C20:3)/Erucic Acid (C22:1)	0.11	0.13
Arachidic Acid (C20:0)	0.12	0.15
(C20:1)	0.30	0.16
(C20:2)	0.30	0.16
Erusic Acid (C22:1)	0.05	0.001
Medium chain (%)		0.65
Long chain saturated (%)	29	34
Monounsaturated (%)	45	45
Polyunsaturated (%)	24	20
Cholesterol		0.34
Gross energy (kcal/liter)	1517	1114
Lactose	40-44	50-59
Total lipid	49-50	65-88

¹Relative percentages of the fatty acid methyl esters.

²Taken immediately postpartum.

³Classified as milk samples collected between 14 and 21 days postpartum.

There are many other components in the sow’s colostrums composition (23, 24, 94, 118, 146), such as:

1. Nutrients

a. Lipids; triacylglycerol, free fatty acids, phospholipids, glycolipids, sphingolipids, sterols, hydrocarbons and fat soluble vitamins);

b. Carbohydrates (lactose, oligosaccharides, galactose, glucose and glycoproteins);

c. Proteins (as1,B, and k-caseins, a-lactalbumin, b-lactoglobulin, lactoferrin, secretory IgA and other immunoglobulins, lysozyme, transferrin, enzymes, hormones and growth factors);

d. Non-protein nitrogenous compounds (urea, creatine, creatine phosphate creatinine, uric acid, amino acids including glutamine, nuclei acids, nucleotides and polyamides); and

e. Water soluble vitamins; f) Macronutrient elements and trace elements (minerals); Copper, zinc, iron and concentrations of some microelements are very low.

3. Growth factors (epidermal growth factor, growth hormone receptors (cytokine), growth hormone-binding protein (PRL-BP) (140), transforming growth factor in the small intestine (TGF-B) (73), nerve growth factor, insulin-like growth factors I and II);

4. Cells (neutrophils, lymphocytes, macrophages, eosinophils, epithelial cells, leucocytes); and

5. Other substances (opioid peptides (casomorphins, lactorphins, casoxins, lactoferroxins), bombesin, lactoferrin, neurotensin) present in the colostrum and milk.

Feeding the early gestating sow with extra Fe, Zn, Cu, Se and Cr resulted in better conception rates and fetal survival and colostrum mineral concentration but not on milk mineral concentration, especially for Cu and Fe (68). Piglets reared in the open field did not show iron deficiencies during lactation, because they were licking some soil and the mineral supplement did not come from the milk composition since this mineral is not variable in milk composition (161).

Colostrum has more concentrated energy throughout protein components and milk energy contribution depends on lipid concentration (Table 1.9).

Many nutritional tables are published worldwide: the National Research Council NRC 1998 (104) in the USA, the Agricultural Research Council (ARC 1981) and British Society of Animal Science in the United Kingdom, in France the Institut National de la Reserche Agronomique (INRA 1984) and Institut Technique du Porc (ITP). The Association Francoise de Zootechnie. Others sources are the Centraal Veevoeder Bureauu (CVB) (www.tessenderlo.com, www.hollandmeat.nl/gb/index.htm) from Netherlands, in Denmark (www.lu,dk), with recent report changes in 2002 for threonine and tryptophan for weaner

Table 1.9. The main components of sow’s colostrum and milk and their relative contribution to gross energy (68)

pigs in www.danskeslagterier.dk. Lists of tables are provided by the Spanish Foundation for the Development of Animal of Animal Nutrition (FEDNA). Also AMIpig, AFRC 1991, and in Australia SCA 1987, AUSPIG and Australian Pork Ltd (PRDC) (48). In addition, Canada and Germany have their own nutritional tables for pigs (50). Feedstuff magazine and large feed processing plants as DEGUSSA, Ajinomoto, www.roche.com and www.basf.com have their own private feed table compositions and requirements. Public organizations and large corporations have also developed their own feed table compositions (www.fao.org, www.rossbreeders.com, w.cobb-vantress.com/ukdist/ukdiv.asp) (49). These publications are reference sources that provide nutritional requirements for swine production; however, each farm may receive nutritional consultation and advising services from a nutritional consultant.

It is not the purpose of this paper to analyze all these nutritional and feed composition tables and their varying recommendations. Rather, the purpose is to demonstrate the difference between institutions (Table 1.10) and to emphasize important research work in many areas of the pork production system by many researchers to determine lysine requirements for various types of breed of pigs (Table 1.11) and the different weight and growing stages (Table 1.12). The NRC 1998 tables recommends 16% higher crude protein levels than the NRC 1988 swine nutrition tables increasing all the amino acid levels for all the weight groups and fixed an energy level for ME in the diet kcal/kg of 3,265. Differences in the tables are not as important as providing digestible, palatable, healthy and in liquid form the creep feed supplements or sow’s milk substitutes.

It is important to consider the size of the animal, its growth rate, feed consumption and feed concentration to satisfy nutrient requirements. This is accomplished by using feeding tables along with background information and proper consultation. The selection of any table is as good as the actual chemical composition analysis applied to every feed component of the diet, the seasonal changes in the crops and industrial feed processing as the current management practices in each farm will change considerably from the feed composition tables.

Table 1.10. Amino acid requirements for piglets of different age and weight (g/kg) (50)

¹ Based on the requirements for pigs weighing 15-90 kg on the assumption that the diet contains 13. MJ/kg.

² Age in weeks: based on the requirements on the assumption that the diet contains 14.1 MJ/kg, which is similar to the energy density recommended by the NRC (1988) for young pigs.

Table 1.11. Total lysine in the diet (grams) for each digestible energy (DEMJ). Ratios (g/MJ) in the diets of growing pigs (3, 138)

Table 1.12. Total basis lysine requirements of different classes of weaned pig (3, 138)

The inclusion of artificial amino acids (lysine, threonine and methionine) in the supplements for baby pigs has been proved to respond in growth rate (160). They do not substitute milk protein but contribute in the balance for the “ideal protein”. In addition, the use of protein sources with high levels of valine and arginine improve growth rate response. The use of these products are determined largely by cost and individual amino acid contribution in the diet. The artificial aminoacid products will no longer be expensive with the construction of the new fermentation plant in the state of Illinois USA in 2004 (Table 1.13).

Table 1.13. Typical inclusion rates of synthetic amino acids in starter feeds (3)

The neonatal pig is more efficient during the first week of age with a milk metabolizable energy (ME) conversion rate of 17 kJ milk ME/g body weight gain. During this stage the suckling pig is able to consume more that 5 times its ME maintenance. Normally this consumption is 3.3 to 3.8 times MEm and to 2.5 times MEm thereafter, reducing the conversion to 19 kJ milk ME/g BW growth. This rapid change in digestion and efficiency accounts for sudden changes in nutrient requirements and frequent changes in diets producing alternative values in different tests. This means that piglets are able to consume large quantities of digestible milk supplements after birth, and will also continue to suckle their dam at the same rate (167).

It has not been determined if there are consequences due to the reduction of colostrum intake or reduced immunoglobulin protection that may increase piglet morbidity and even mortality with the inclusion of a milk substitute. In addition, there are no studies of supplementing piglets during early lactation to determine if sow’s milk reduces allergic reaction and provides a protective inflammatory factor that reduces allergic reaction from a feed source such as soybean meal. Acclimating pigs to the consumption of viable quantities of solid feed > 15 MJ ME/kg before they are weaned is commensurate with normal growth after weaning (1).

Suckling piglets may have depressed milk ingestion and low creep feed consumption because protein and mineral level in the sow’s milk and the high % CP in the supplement may cause an increase of urinary nitrogen and minerals excretions with a consequent body water loss (162). If the heater lamp raises the temperature in the farrowing creep, it may raise fresh water requirements for neonates. Many farrowing facilities do not provide water for suckling pigs and this depresses milk and total feed dry matter consumption. Neonate piglets can start drinking water after 2 days of age, from 0 to 200 ml/day with an average of 46 ml, but some studies report lesser amounts (104).

The gradual process of weaning by creep feeding provides a transitional training eating period to stimulate free choice feed consumption > 7 g of food/day at 14 days of age and about > 127 g/day at 28 days of age (7). Before weaning at 19-25 days, a lactating sow is able to produce a piglet growing at 300 g BW/day, providing 4.0 MJDE of milk/pig/day, supplementing feed with extra 1.5 MJDE/day containing 19.0 MJDE/kg. In order to support a growth rate of 300 g/day after weaning, the diet should contain > 27.5 MJ DE/kg to sustain a feed intake of 200 grams/day that will provide requirements of 5.5 MJ DE/day (44). Normal (uninterrupted) growth patterns during lactation and after weaning are seen only under the highest standards of husbandry and nutrition practices (168). These accomplishments could be achieved by providing experiences in feed consumption for the piglets and particularly in drinking water before weaning (137).

The second half of lactation after 14 days of age and the immediate post-weaning period are commonly identified as major periods when the deficit in energy intake is the most pronounced. This may cause a slow daily gain rate or even a weight lost with a reduction in muscular cell count. However, a low milk intake during the neonatal period also influences the ability of the piglet to survive and thrive because the low weight piglet is more willing to try creep feeding (2). The major physiological objective of milk and feed consumption during the suckling and weaning phases should be to maximize piglet growth and develop insulation tissue in the endodermis or superficial fat. It is also possible that lipid molecules are carriers of immune factors and precursors of hormonal changes that protect the piglet from diseases and may be a physical barrier for other pathogens. Therefore, because protein deposition increases linearly with energy intake in the suckling pig, maximization of protein deposition also implies maximization of energy intake.

If the piglet gets heavier during the neonatal period it will be fatter, and there is a belief that this will increase back fat thickness affecting carcass composition at slaughter-market time. It is unlikely that the extra fat deposited in the young pig will make a large contribution to the total stored fat in the market pig. There will be too many metabolic and physiological changes before the animal reaches market weight, and this early fat will not be stored in the adipose tissue at the finishing stage. Weaning pigs at 14 days of age have a potential to be fatter at 23 weeks if they had a challenge with post weaning syndrome (PWS) (54). Maybe an effect of extra feed consumed at the end of the finishing period and less protein accretion due to less muscular cells formation in the neonatal piglet increases back fat thickness. This compensatory growth is not always correlated to PWS.

There is little information in the literature on the estimations of energy cost of maintenance and growth in the suckling piglet due to the difficulties in determining milk energy intake precisely. These estimations are also difficult to establish immediately after weaning because of the usual low intake and the ensuing negative energy balance during 1-5 days (2). This is a good explanation for constant changes in the nutritional requirements of pigs and differences between authors and institutions.

There is an obvious interest to maximize the efficiency of any diet or to supply the nutrient requirements for every type of breed and age or weight of any pig. The modern nutritionist should also look to animal nutrition and feeding methods used and the importance of considering the effects on the animal welfare, the quality of the product and the impact on the environment (53, 137). Differences in these factors may change the nutrient requirements of the animal to match the market or regulation needs in different parts of the world.

A summary of values for metabolizable energy requirements for maintenance (MEm) and efficiencies of ME intake for total energy retention (k-g) and for energy retained as protein (k-p) and fat (k-f) is given in Table 1.14. MEm includes the energy cost of basal metabolism, physical activity and thermoregulation. In the suckling pig reported MEm values amounts from 340 kJ ME/kg BW^0.75per day to 470 kJ ME/kg BW^0.75per day. There is small variation in the suckling pig for energy retained and protein accretion compared with the weaning pig range for these concepts. The suckling piglet retains fat from feed to body fat in a 1:1 ratio but not after weaning (19).

In the suckling pig, the energy cost of standing is 0.18 kJ BW^0.75per minute, but in practice the total energy cost of suckling and standing activity is very variable and difficult to assess, especially in outdoor rearing conditions. On the basis that 1g sow’s milk supplies 4.75 kJ ME it is not considered a concentrated feed so the animal have to suck high volumes of milk. The concentrated source of 1g weaning diet supplies >15 kJ ME and the animal needs small amounts to meet maintenance requirements. Sow milk is very digestible (0.99-1.00) because of its high biological value, but values for DE or ME varied widely in relation to its fat content. The fat content in the dry matter of sow milk is about 400 g/kg (44). The true digestibility of sow’s milk reported is 88% for nitrogen, and the average amino acids digestibility is 92%, but for amino acids cystine and threonine the digestibility is 88%

Table 1.14. Summary of the estimated values for maintenance energy requirements (MEm) and for efficiency of metabolizable energy intake for growth (k-g), protein (k-p) and fat (k-f) deposition (19)

and for methionine, histidine, and glutamic acid is 100%. The average digestibility for all the amino acids is 92%±4% (118). This is an indication that it is difficult to compare the digestibility of milk for different herds, because milk composition variability will affect analysis results thus there are several methods to determine nutrient requirements for suckling pigs.

Piglets of 3.82 kg body weight digest human milk very well > 90%, but certain amino acids such threonine, valine and phenylalanine are not absorbed as well (98). This paper did not explain the cause and origin of the effect due to the quality properties of the human milk or if it was a deficiency of enzymes in the

	Fresh sample
Variable	g/kg	KJ/kg	% of total gross energy
Colostrum (3 h after farrowing)
Total crude protein	175	4148	56.5
Total immunoglobulins	96
Pre-albumin+albumin	47
Casein	32
Total lipids	67	2653	36.1
Lactose	32	544	7.4
Total energy		7345	100.0

Milk (day 7 of lactation)
Total crude protein	56	1327	21.5
Total immunoglobulins	20
Pre-albumin+albumin	13
Casein	23
Total lipids	101	4000	65.0
Lactose	49	833	13.5
Total energy		6160	100.0

	Protein deposition	Weight	Lysine/DE ratio
Genotype	Rate (g/day)	(kg)	Castrate	Gilt	Boar
Unimproved	100	<25	0.78	0.80	0.83
Unimproved	100	25-55	0.73	0.75	0.78
Average	125	<25	0.85	0.85	0.88
Average	125	25-55	0.78	0.80	0.83
High	150	<25	0.88	0.90	0.93
High	150	25-55	0.83	0.85	0.88
Hybrid	175	<25	1.20	1.20	1.20
Hybrid	175	25-55	1.10	1.10	1.10

Diet type	Weight band (kg)	Total lysine (g/kg)
Pre-starter	<5	17-18
	3-5	15
	<5	16.5-17.5
Starter	5-7	15-16
	5-10	13.5
	5-10	14
	5-10	16.0-16.5
Link	7.0-11.5	13.5-14.5
Link	7-12	15-16
Early grower	11.5-23.0	12.5-13.5
	10-20	11.5
	10-25	11
	10-25	15
Grower	15-25	10.5
Grower	12-25	14-15

	MEm
	(kJ ME/kg BW0.75)	(k-g)	(k-p)	(k-f)
Suckling pig	340-470	0.70-0.73	0.56	1.0
Weaned range	420-550	0.60-0.79	0.50-0.66	0.73-0.84

	Pig weight (kg) or age (weeks)
	NRC (1988)	ARC (1981)¹
Amino acid	1-5	5-10	10-20	20-50	50-110	0-3²	3-8²	15-50	50-90
Lysine	14.0	11.5	9.5	7.5	6.0	15.8	13.8	11.0	7.8
Arginine	6.0	5.0	4.0	2.5	1.0	-	-	-	-
Histidine	3.6	3.1	2.5	2.2	1.8	5.2	4.5	3.6	2.6
Isoleucine	7.6	6.5	5.3	4.6	3.8	8.6	7.5	6.0	4.3
Leucine	10.0	8.5	7.0	6.0	5.0	15.8	13.8	11.0	7.8
Methionine
+cysteine	6.8	5.8	4.8	4.1	3.4	7.9	6.9	5.5	3.9
Phenylalanine
+tyrosine	11.0	9.4	7.7	6.6	5.5	15.1	13.3	10.4	7.5
Threonine	8.0	6.8	5.6	4.8	4.0	9.4	8.3	6.5	4.7
Tryptophan	2.0	1.7	1.4	1.2	1.0	2.3	2.0	1.6	1.2
Valine	8.0	6.8	5.6	4.8	4.0	11.0	9.7	7.7	5.5

Rates	Lysine	Methionine	Threonine	Tryptophan
Kg/Ton	2-5	0.5-2	0.5-1.5	0-1