WO1997033486A1

WO1997033486A1 - Sow lactation diets supplemented with branched chain amino acids

Info

Publication number: WO1997033486A1
Application number: PCT/US1997/002886
Authority: WO
Inventors: B. T. Richert; Robert D. Goodband; Michael D. Tokach; J. L. Nelssen
Original assignee: Kansas State University Research Foundation
Priority date: 1996-03-15
Filing date: 1997-02-26
Publication date: 1997-09-18
Also published as: AU1972497A

Abstract

Sow lactation diets supplemented with branched chain amino acids are provided which increase pig and litter weaning weights by improving the nutritional quality of sow's milk. The diets of the invention include a total protein content of from about 12 to 30 % by weight, a total lysine content of at least about 0.9 % by weight, and a total branched chain amino acids content sufficient to give a total branched chain amino acids:lysine ratio of at least 3.24:1.

Description

SOW LACTATION DIETS SUPPLEMENTED WITH BRANCHED CHAIN AMINO ACIDS

Background of the Invention

1. Field of the Invention

The present invention is broadly concerned with sow lactation diets which increase pig and litter weaning weights. More particularly, the invention relates to sow lactation diets, and corresponding methods, wherein addition of a minor amount of synthetic isoleucine and/or leucine yields unexpectedly high pig and litter weaning weights.

2. Description of the Prior Art

The branched chain amino acids (i.e., leucine, isoleucine, and valine) are essential amino acids with respect to swine. Therefore, these amino acids need to be provided in the swine diet. Historically, branched chain amino acids have received little attention in swine nutrition research. The valine and isoleucine requirements of lactating sows have been examined by Haught and Speer (1977) and Rousselow and Speer (1980). No research has evaluated the ability of the individual branched chain amino acids to spare each other in meeting the needs of the mammary gland for milk synthesis. Additionally, only one trial has examined the effect of increasing total branched chain amino acids (TBCAA) (Trottier and Easter, 1995).

The dietary requirement for TBCAA has implications in practical diet formulation. A com-soybean meal lactation diet (formulated to .90% lysine) contains 3.33% TBCAA. When 0.15% synthetic lysine is added to this diet, TBCAA content drops to 3.05%. Diets become deficient in valine and possibly isoleucine since most of the TBCAA contribution is from leucine (1.7%), (Tokach et al., 1993; Richert et al., 1996b). Recently, Tokach et al. (1996) described a diet containing added valine which results in increased pig and litter weaning weight. However, this reference does not teach or suggest use of other synthetic branched chain amino acids in sow lactation diets.

Summary of the Invention

The present invention is directed to improved sow lactation diets which increase pig and litter weaning weights. In other aspects of the invention, methods of formulating such improved diets are provided, as well as methods of feeding lactating sows. The invention is predicated upon the discovery that, contrary to the accepted wisdom in the art, increasing the amounts of TBCAA in the diet improves the nutritional value of sow's milk. This improved nutritional value consists of increased protein and lipid concentrations and increased dry milk matter. Within the protein fraction of milk, increasing the TBCAA increases the concentration of casein protein at the expense of whey proteins, thereby resulting in milk which provides a greater quantity of amino acids and energy. The invention is further predicated upon the idea that the lactating sow can convert one branched chain amino acid into another. Thus, a high level of one branched chain amino acid in the diet may partially replace the need for the other branched chain amino acids.

Broadly speaking, the diets of the invention include a total protein content of from about 12 to 30% by weight (calculated as 6.25 X total nitrogen). At least a portion of the total protein content is preferably derived from cereal grain (e.g., corn, wheat, barley, rye, oats, sorghum, and millet) and oil seed (e.g., soybean and peanut). In addition, the total lysine content of the diets is at least 0.9% by weight. The diets also include a TBCAA content sufficient to give a TBCAA:lysine ratio of at least 3.24: 1. In accordance with the invention, at least about 0.05% by weight of synthetic amino acid(s) selected from the group consisting of isoleucine, leucine and mixtures thereof are added to the diet.

Detailed Description of the Preferred Embodiment

The following example sets forth the most preferred lactating sow diet in accordance with the invention, as well as a method of feeding thereof. The example is set forth by illustration only, and nothing therein shall be taken as a limitation upon the overall scope of the invention.

Example Animals. One hundred eighty-five parity 1 (130) and parity 2 (55) sows from the Kansas State University Swine Teaching and Research farm were used in this experiment. All sows were maternal line (PIC Line C-15) bred to terminal line (PIC Line 326) boars. During gestation, sows were housed in outside dirt lots and fed in individual stalls. Gestating sows were fed 1.8 to 2.3 kg/d depending on body condition. The gestation diet was a sorghum-soybean meal-based diet formulated to .65% lysine, .90% Ca, and .80% P. On d 109^{^} of gestation, sows were moved into farrowing crates (2.1 x .6 m) with an area (2.1 * .6 m) for newborn pigs on each side of the crate in an environmentally regulated farrowing house. Temperature in the farrowing house was maintained between 20 and 30 °C with heat lamps to provide supplemental heat to the pigs. On d 110 of gestation, all sows were fed 2.3 kg/d of the control diet (.50% isoleucine, .72% valine) until farrowing, at which time sows were allotted to one of the seven dietary treatments. Treatments were allotted randomly within groups of seven as sows farrowed to minimize variation in lactation length between treatments. Sows farrowed from November, 1994 through June, 1995. Three or four observations were made per treatment per lactation group, and seven lactation groups (blocks) were used.

On day 1 , pigs received 2 mL of iron dextran solution, were ear notched, and had tails and naval cords docked. Litter size was equalized by 24 h postfarrowing, and all sows began the study with at least 10 pigs.

Diet Formulation. The lactation diets (Table 3) were formulated to be in excess (at least 110% relative to lysine) of all amino acid requirement estimates based on ratios relative to lysine derived from NRC (1988) and ARC (1981), except for isoleucine and valine. All other nutrients were in excess of NRC (1988) requirement estimates. Diets were formulated to .90% lysine, .90% Ca, and .80% P. The control diet contained .50% isoleucine and .72% valine. Crystalline L-isoleucine and L- valine replaced corn starch in the control diet at .35% increments to create the remaining six diets. The treatments included three levels of valine (.72, 1.07%, or 1.42%) and three levels of isoleucine (.50, .85, and 1.20%). The low and intermediate levels of valine were combined with all three levels of isoleucine, but the highest level of valine was combined only with the low level of isoleucine. This combination of treatments provided TBCAA levels of 2.6, 2.9, 3.3, and 3.6%. Samples of each diet were collected for CP and amino acid analysis and stored at -20 °C. Analyzed dietary amino acid levels were similar to calculated values (Table 4).

Sow Criteria. Sows were assigned to dietary treatments as they farrowed and received experimental diets within 24 h postpartum. Sows were allowed ad libitum access to feed and water from parturition until weaning. Feed intake was determined weekly. Orts were collected and weighed once each week. Sows were weighed and scanned using real-time ultrasound (Aloka 210; Corometrics Medical Systems, Inc., Wallingford CT) 6 cm off the midline on both sides of the body at the last rib to determine backfat thickness within 24 h postpartum and at weaning (d 20). Pigs were cross-fostered among sows irrespective of dietary treatment until 24 h postparturition to standardize litters to at least 10 pigs. No cross fostering or replacement of pigs was done after 24 h postfarrowing. Pigs and sows were weighed at d 0, 7, and 14 and weaning. Creep feed was not offered to litters. On the day of weaning, sows were moved to an environmentally regulated breeding facility for observation of estrus. Sows were checked for signs of estrus daily for 10 days postweaning and were determined to be in estrus when the sow would stand to be mounted by a boar..

Milk Criteria. Twelve sows per treatment (84 total) were milked manually on either d 17 or 18 of lactation. Sows were separated from their litters for a minimum of

45 min before milking. All sows were milked approximately 2 h after the initial morning feeding. Sows were restrained with a nose snare, and milk was collected from the first and last productive glands on both sides of the body. Each gland was milked until approximately 75 mL of milk was collected. Milk letdown was enhanced by infusing 10 IU of oxytocin into an ear vein of the sow. Samples from each gland were pooled for chemical analysis and stored at 2 to 4°C. All analyses were conducted within 48 h after collection. Milk DM, CP, and ash were determined according to AOAC (1990) procedures. Milk fat was determined using the Monjonnier procedure (AOAC, 1990). Milk lactose was determined by difference of the determined DM components and the total DM. Milk protein fractions were determined by modification of both the Rowland (1938) and renin procedures. Briefly, 25 mL of whole milk was mixed with 25 mL of distilled water to dilute it to a protein concentration similar to bovine milk, for which the Rowland procedure was developed. This was to ensure the complete extraction of the protein N fractions. The concentrations of N in the protein fractions were determined using a macro-kjeldahl. The renin procedure used 5 mL of milk (milk weight was recorded and used for calculations) diluted with 5 mL of distilled water. The mixture then was swirled, and .25 mL of renin was added. This mixture was swirled and then placed in a 37° C water bath for 1 h. The coagulated milk was broken up physically with a stainless steel stir rod and centrifuged at 3,000 * g for 15 min. Following separation, the whey and fat were poured into a separate vial from the casein pellet and both fractions were frozen at - 20 °C until N analysis was performed by macro-kjeldahl.

Statistical Analysis. The GLM procedure of SAS ( 1988) was used to determine treatment effects. Isoleucine. Dietary isoleucine had no effect on number of pigs weaned (* = 10.9; Table 5) or survival rate (><= 98.1%, data not shown). Increasing isoleucine across valine levels resulted in increased litter weights (linear, P < .07) and weight gains (linear, P < .06) at d 7 and 14 and weaning (Table 5). Litter weaning weight increased (linear; P < .06) as isoleucine increased to 1.20% in the diet; however, the greatest increase (84% of the incremental gain) was observed at .85% dietary isoleucine. Increasing dietary isoleucine increased sow BW loss (Table 6; linear, P < .01) but had no effect on sow backfat loss (P < .14). Dietary isoleucine had no effect on sow feed intake (P > .77), but isoleucine intake (g/d) increased (linear; P < .0001) as isoleucine increased in the diet.

Increasing isoleucine from .50 to 1.20% at 1.07% valine resulted in increased litter weights at d 7 and 14 and weaning (quadratic; P < .06, P < .05, P < .10, respectively) and tended to increase litter weight gain from d 0 to 14 (linear and quadratic, P < .15). Increasing isoleucine at 1.07% valine increased sow BW loss (Table 6; linear, P < .01). Dietary isoleucine had no effect on days to estrus (Table 6;

P < .18) for sows fed diets containing 1.07% valine.

TBCAA. Total branched chain amino acids increased litter weights and weight gains (Table 5) at d 7 and 14 and weaning (linear; P < .07, .03, and .02, respectively). The level of TBCAA in the diet did not affect ADFI (P < .20). However, TBCAA intakes increased (linear, P < .0001) and isoleucine and valine intakes increased

(quadratic, P < .0001) as dietary TBCAA increased in the diet (Table 6). Increasing

TBCAA in the diet resulted in increased sow BW and backfat losses (linear, P < .001).

Milk Composition. No differences occurred in relative values for the casein and whey fractions between the Rowland (1938) and the renin procedures. The Rowland (1938) procedure was more precise in results (lower coefficient of variation); therefore values using the Rowland procedure are presented (Table 7). Milk composition was affected by dietary isoleucine, valine and TBCAA levels (Table 7). The only milk criterion to be increased by increasing valine across isoleucine levels (Table 7) was the other N fraction (P < .07) which includes all other N besides whey and casein proteins (ie., urea N, sloughed cellular N, free amino acids). Increasing isoleucine across valine levels of .72 and 1.07% (Table 7) increased milk DM, CP, fat, and casein (linear, P < .01) and decreased whey (linear, P < .06) and other N fractions (linear, P < .01).

Increasing dietary valine from .72 to 1.42% at .50% isoleucine resulted in increased milk DM (linear, P 004; quadratic, P < .01); lipid (linear, P < .01); and other N (quadratic, P < .06) and decreased lactose (linear, P < .10). Increasing isoleucine at either .72 or 1.07% valine increased milk DM (linear, P < .05); CP (linear, P < .09); and lipid (linear, P < .04). In addition, increasing isoleucine at 1.07% valine increased the casein milk protein fraction (linear, P < .03) and decreased the whey (linear, P < .09) and other N fractions (linear, P < .03; quadratic, P < .11). Increasing dietary TBCAA increased milk DM (linear, P < .002); lipid ( linear, P < .005); and casein protein fractions (linear, P < .08) and decreased the whey fraction (linear, P < .10).

Conclusions Increasing dietary valine from .72 to 1.07% across isoleucine levels resulted in a 2 kg increase in litter weight gain with no interaction between valine and isoleucine levels. This suggests that the responses to valine and isoleucine for litter weaning weight are independent.

Increasing isoleucine at low valine (.72%) provided a numerical increase in litter weights and litter weight gains with the greatest response observed at 1.2% isoleucine.

Increasing isoleucine at the intermediate valine level (1.07%) also increased litter weaning weights and weight gains; however, the response tended to be when comparing isoleucine at the intermediate valine level demonstrates that, when valine is adequate (1.07%), the isoleucine requirement is approximately .85% of the diet (95% of lysine). This is approximately .2% greater than the requirement estimates for the lactating sow by NRC (1988) and ARC (1981). Haught and Speer (1977) reported a total isoleucine requirement estimate for the lactating sow of .39% (71% of lysine), with sows that were nursing nine pigs and had piglet weight gains from d 7 to 21 of 2.38 kg. In our experiment, an average of 10.9 pigs were weaned and pig weight gain was 3.27 kg from d 7 to 20 of lactation for sows fed the .85% isoleucine and 1.07% valine diet. This corresponds to an isoleucine requirement of 95% of lysine, greater than previous estimates.

Increasing both isoleucine and valine in the diet increased sow weight loss during lactation. In the case of valine, there also was decreasing feed intake and increased sow backfat loss with increased dietary valine to 1.07%. The .2 kg reduction in daily feed intake coupled with a 2 kg increase in litter weaning weight gain as valine increased to 1.07% would easily account for the 2.6 kg reduction in sow BW and 1.2 mm backfat loss. Increasing isoleucine linearly decreased sow BW during lactation and is likely due to the increased milk concentrations of lipid and protein. Previous trials (Richert et al., 1996a,b) however, did not observe a valine response to sow BW loss with sows having similar and lower feed intakes.

The data also suggest that a total branched chain amino acid requirement exists for the lactating sow. Litter weaning weight increased (linear; P < .02) through 3.6% TBCAA. However, the litter weaning weight at that level was matched at 3.24% dietary TBCAA, when the 3.24% level was provided by balanced levels of isoleucine (.85%), valine (1.07%), and leucine (1.35%) as compared to high levels of isoleucine or valine alone. This balanced combination of TBCAA provided numerically greater (P < .16) litter and pig growth performance than the other diets containing 3.3% TBCAA. Therefore, the TBCAA requirement is at least 3.24% (203 g/d) in the lactating sow diet when a balance of the branched chain amino acids are fed and is higher when an imbalanced branched chain amino acid profile is fed.

Trottier and Easter (1995) fed a standard corn-soybean meal lactation diet that was supplemented with 1.56% branched chain amino acids, to provide a dietary TBCAA level of 4.37% and reported only a small increase (1.2 kg) in litter weaning weights. The response in that trial may have been related to the low dietary lysine level (.68%) and/or the low number of pigs per litter (8). Tokach et al. (1992) and Pettigrew (1993) demonstrated that feeding a deficient lysine diet will limit the ability of the lactating sow to synthesize milk, thus limiting litter growth rate. Also, the 4.37% dietary TBCAA might have been high enough to increase the activity of the non¬ specific branched chain amino acid decarboxylase enzyme and lead to catabolism of the additional branched chain amino acids, thereby limiting their effect on milk production. It is not known at this time if it is best to have this enzyme complex fully active or not with high branched chain amino acid diets to maximize litter growth rates. It is likely that a fully active enzyme complex would provide the metabolite that would stimulate milk synthesis rates, similar to the leucine metabolite increasing milk fat (Nissen et al., 1994). However, the possibility of the amino acid its self stimulating enzyme complexes is still a very like candidate also.

The lower percentage (74.3 vs 96.3%) of sows returning to estrus when fed higher levels of isoleucine (.85 and 1.20%) at the deficient valine level compared to the higher isoleucine levels at the intermediate valine level is difficult to explain. This response suggests that there is an altered hormonal or metabolite balance occurs when diets deficient in valine and high in isoleucine are fed. This may be indicative of an amino acid imbalance between the branched chain amino acids. An alternative explanation may be a chance occurrence because of the relatively low number of sows (24 to 28 per treatment) used for reproductive data.

Valine increased milk fat and DM concentrations, with minimal effect on total milk protein concentration and without altering the relative distribution of protein fractions. However, isoleucine increased milk DM, CP, and fat. Isoleucine also consistently increased the casein fraction of the milk protein and decreased the whey fractions. The altering of whey proteins is in agreement with Poso and Lindberg (1994), who reported that, in the lactating dairy cow, the branched chain amino acids were thought to alter the export proteins (albumin, prealbumin, and transferrrin) from the liver, thereby altering the amount entering the milk and milk protein. However, when the total whey excreted in the milk is calculated by multiplying the whey fraction percentage and the CP percentage together, there is very little difference between treatments in total whey output. This would indicate that the whey proteins truly aren't affected by the isoleucine and(or) valine levels in the diet. The increase in milk fat by the inclusion of high levels of isoleucine and valine in the diet is similar to the response observed by Nissen et al. (1994) with the leucine metabolite β-hydoxy-β-methyl butyrate. However, they reported that milk fat concentrations remained elevated through d 10 of lactation and then decreased below the concentration of the control sows by d 21. The change in milk composition over time were not measured in the present study; however, contrary to their findings, milk fat was higher than the control level at the end of lactation in the experiment when sows were fed diets containing higher levels of valine and(or) isoleucine. Increasing milk fat concentration alone does not always result in increased pig growth (Coffey et al., 1982; Noblet and Etienne, 1986). Higher milk fat provides greater energy for the pig's growth, but this may be at the expense of other important nutrients or volume of milk produced.

The relative increase in the casein fraction and corresponding reduction in the whey fraction of the milk protein has not been reported before as a result of changing dietary amino acids. The percentages for casein fraction (51.6 to 57.9%) are similar to those reported by Brent et al. ( 1973) and Martin (personal communication), 54 and 51 % of milk protein, respectively. The whey fraction as a percentage of milk protein is in disagreement with Klobasa et al. (1987; 34% vs 53%), but is similar to that reported by Brent et al. (1973). The reason behind the large discrepancy between our results and those of Klobasa et al. (1987) is likely the different procedures used to separate the milk protein fractions. They defatted milk samples prior to conducting the fractionation, whereas in our trial and that of Brent et al. (1973), whole milk was used for the N fractionation procedure. By defatting the milk prior to N fraction analysis, a 13% loss of milk protein with the fat globules occurs (Wu and Knabe, 1994). Because casein has a greater concentration of lysine as a percentage of protein than whey (8.1 vs 7.1%, Jurgens, 1988), milk with more casein may provide greater amounts of the first limiting amino acid for growth (lysine), improving the milk's biological value for the pig. When the increase in milk fat is considered with the alterations in ratios of casein and whey proteins by the high isoleucine treatments, the milk has a much greater nutritional value and is likely one of the reasons for the observed increased pig growth for the increasing isoleucine levels. Valine did not alter the milk protein fractions, and so the possibility remains that increased dietary valine (and isoleucine) may have increased total milk volume output by the sow; however, this was not measured in our experiment. The isoleucine requirement of the high-producing lactating sow may be higher than current National Research Council and Agricultural Research Council estimates, but is not greater than 94% of lysine. The total branched chain amino acid requirement for high-producing lactating sows is at least 203 g/d. High dietary valine appears to spare a portion of the isoleucine requirement because the isoleucine response plateaus at .85% dietary isoleucine when valine is dietarily adequate and valine increased litter weights linearly, regardless of isoleucine level. The importance of valine and isoleucine for milk production must be considered when formulating diets for lactating sows.

Tables 1 and 2 set forth broad, preferred and most preferred ranges for the ingredients of sow lactation diets in accordance with the invention, and such ranges for TBCAA:lysine.

Table 1. Broad ranges, preferred ranges, and most preferred ranges of ingredients of the sow lactation diets of the present invention.

Ingredient Broad Range Preferred Range Most Preferred (%) (%) Range (%)

Wheat ≥O 5-50 20-30

Corn ≥ IO 15-90 40-70

Soybean meal ≥ l 5-40 5-30

Total lysine ≥0.9 .9-1.5 .9-1.2

Total isoleucine ≥0.75 ≥0.85 0.85-1.2

Total leucine ≥ 1.35 ≥ 1.5 ≥ 1.7

Total valine ≥0.72 ≥.9 .90-1.2

Total synthetic L- ≥O ≥.05 ≥Λ lysine

Total synthetic L- ≥0.05 ≥.ϊ Λ-.5 isoleucine and/or synthetic L-leucine

Table 2. Broad range, preferred range, and most preferred range of TBCAA:lysine in the present invention.

Ratio Broad Range Preferred Range Most Preferred Range

TBCAA:lysine ≥3.24:1 3.24: 1-4.02:1 3.63:1-4.02:1

Table 3. Diet composition (as-fed basis)³

Ingredient Control Diet, %

Corn 55.085 Hard red winter wheat 26.635

Soybean meal, (47% CP) 7.475

Spray-dried blood meal 1.428

Soybean oil 3.000

Monocalcium phosphate 2.354 Limestone 1.052

Salt .500

Corn starch^b 1.050 Sow add pack^c .250

Vitamin premix^d .250 Trace mineral premix^e .150

L-lysine-HCl .383

L-threonine .220

DL-methionine .113

L-tryptophan .055 Total 100.0

"Basal diet was formulated to 13.6% CP, .90% lysine, .72% valine, .50% isoleucine,

1.35% leucine, .90% Ca and .80% P. ^bCorn starch was replaced in .35% increments with L-valine or L-isoleucine or both to provide the remaining six experimental diets. ^cSupplied per kilogram of diet: 386 mg choline, .22 mg biotin, 1.65 mg folic acid.

Supplied per kilogram of diet: 11,025 IU vitamin A, 1,103 IU vitamin D₃, 44.1 IU vitamin E, 4.4 mg menadione sodium bisulfate, 8.3 mg riboflavin, 28.7 mg pantothenic acid (as d-calcium pantothenate), 49.6 mg niacin, 165 mg choline, and .03 mg vitamin B₁₂.

'Supplied per kilogram of diet: 39.7 mg Mn, 165 mg Fe, 165 mg Zn, 16.5 mg Cu, .30 mg I, and .30 mg Se. Table 4. Chemical analysis of experimental diets and ingredients (as-fed basis)*

Valine: .72 1.07 1.42

Isoleucine, %: .50 .85 1.20 .50 .85 1.20 .50

Item TBCAA^b: 2.57 2.92 3.27 2.92 3.27 3.62 3.27 Com Wheat

CP, % 14.1 14.4 14.9 14.4 14.8 15.0 14.8 8.65 12.57

Amino acids, %

Isoleucine .49 .79 1.18 .47 .88 1.17 .48 .27 .46

Valine .71 .73 .71 1.05 1.06 1.07 1.39 .37 .56

Leucine 1.37 1.36 1.36 1.34 1.36 1.36 1.36 1.04 .91

Arginine .72 .71 .73 .72 .74 .72 .74 .42 .61

Histidine .42 .41 .43 .43 .43 .43 .43 .28 .32

Lysine .92 .91 .92 .90 .92 .93 .94 .30 .39

Methionine .33 .32 .32 .32 .34 .32 .32 .19 .21

Cysteine .27 .27 .27 .27 .27 .28 .28 .21 .33

Threonine .67 .68 .68 .66 .70 .68 .67 .32 .38

Tryptophan .20 .19 .19 .20 .20 .20 .20 .05 .16

Phenylalanine .71 .70 .70 .68 .71 .71 .71 .44 .61

Tyrosine .43 .43 .42 .41 .42 .43 .43 .28 .34

^■Values represent the mean of 3 pooled feed samples with 2 batches of each diet per sample. Total branched chain amino acids (isoleucine + valine + leucine).

Statistical Analysis (P < )

Main Effects Valine at

Isoleucine .50% Isoleucine^f TBCAA⁸

Valine Lin. Quad. Val He Lin. Quad. Lin. Quad.

Feed intake

ADFI .08 .92 .77 .22 .83 .15 .20 .58

Lysine .08 .92 .77 .22 .83 .15 .20 .58

Valine .0001 .88 .54 .31 .0001 .18 .0001 .0001

Isoleucine .05 .0001 .89 .07 .83 .15 .0001 .0001

TBCAA .0001 .0001 .72 .17 .0001 .16 .0001 .44

Sow BW d O .08 .13 .64 .81 .62 .21 .95 .48

Change .02 .01 .44 .64 .53 .54 .001 .15

Sow backfat d O .04 .62 .08 .003 .03 .02 .64 .0002

Change .0001 .14 .74 .63 .04 .13 .001 .37

Days to estrus .07 .97 .43 .38 .54 .21 .16 .68

"Litter size after cross-fostering and lactation length used as covariates.

Total branched chain amino acids (isoleucine + valine + leucine).

'Initial sow BW used as a covariate. initial sow backfat used as a covariate.

'Percent of sows in estrus b d 10 postweaning. Values differ (P<.06) based on Chi-square distribution.

•Contrasting dietary valine levels of .72, 1.07, and 1.42% at .50% dietary isoleucine.

Contrasting means of total branched chain amino acid levels 2.57, 2.924 3.27, and 3.62%.

Table 7. The effects of valine and isoleucine on milk composition, %'

Valine, %: .72 1.07 1.42

Isoleucine, %: .50 .85 1.20 .50 .85 1.20 .50

Item TBCAA, %^b: 2.57 2.92 3.27 2.92 3.27 3.62 3.27 CV

DM 16.17 16.8 17.1 15.8 17.02 17.33 17.6 5.1 6

CP 5.16 5.31 5.61 4.94 5.39 5.33 5.30 9.5

Fat 5.76 6.00 6.67 5.87 6.38 6.66 6.89 14.7

Lactose 4.47 4.48 4.24 4.50 4.29 4.45 4.23 7.6

Ash .78 .77 .77 .79 .80 .75 .76 6.5

N fractions

Casein 53.9 55.2 57.1 51.6 55.3 57.9 53.9 1 1.5

Whey 35.5 35.0 33.2 36.2 34.7 31.9 34.9 17.1

Other' 10.6 9.8 9.7 12.3 10.0 10.3 11.2 18.5

Statistical Analysis (P < )

Main Effects Valine at

Isoleucine .50% Isoleucine* TBC :AA^C

Valine Lin. Quad. Val He Lin. Quad. Lin. Quad

DM .93 .0002 .25 .62 .004 .01 .002 .84

CP .25 .005 .47 .42 .50 .11 .20 .77

Fat .47 .002 .83 .72 .01 .23 .005 .71

Lactose .85 .24 .77 .25 .10 .22 .57 .38

Ash .81 .19 .58 .33 .36 .53 .20 .55

N fractions

Casein .73 .01 .94 .67 .97 .33 .08 .33

Whey .82 .06 .65 .85 .83 .67 .10 .39

Other .07 .01 .10 .41 .43 .06 .52 .61

'Litter size postfostering used as a covariate.

"Total branched chain amino acids (isoleucine + valine + leucine). ^cOther=All other N (free amino acids, urea N, sloughed cellular N). ^dContrasting dietary valine levels of .72, 1.07, and 1.42% at .50% dietary isoleucine.

'Contrasting means of total branched chain amino acid levels 2.57, 2.92, 3.27, and 3.62%.

Claims

Ciaims:

1. A sow lactation diet comprising a total protein content of from about 12 to 30% by weight, a total lysine content of at least about 0.9% by weight, and a TBCAA content sufficient to give a TBCAA: lysine ratio of at least 3.24:1, wherein said TBCAA content includes at least about 0.05% by weight of synthetic branched chain amino acid(s) selected from the group consisting of isoleucine, leucine and mixtures thereof.

2. The diet of claim 1 , wherein at least a portion of said total protein content is derived from a protein source selected from a group consisting of cereal grain and oil seed.

3. The diet of claim 1, wherein said diet includes a wheat content of from about 5 to 50% by weight.

4. The diet of claim 1 , wherein said diet includes a corn content of at least about 10%.

5. The diet of claim 1 , wherein said diet includes a soybean meal content of at least about 1%.

6. The diet of claim 1, wherein said diet includes a total lysine content of from about 0.9-1.2% by weight.

7. The diet of claim 1 , wherein said diet includes a total isoleucine content of at least about 0.75% by weight.

8. The diet of claim 1, wherein said diet includes a total leucine content of at least about 1.35% by weight.

9. The diet of claim 1, wherein said diet includes a total valine content of at least about 0.72% by weight.

10. The diet of claim 1, wherein said diet includes at least about 0.1% by weight of synthetic branched chain amino acid(s) selected from the group consisting of isoleucine, leucine and mixtures thereof.

11. A method of formulating an improved sow lactation diet comprising providing a starting sow lactation diet having a total protein content of from about 12 to 30% by weight and a total lysine content of at least about 0.9% by weight, and incorporating into said starting sow lactation diet at least about 0.05% by weight of synthetic branched chain amino acid(s) selected from the group consisting of isoleucine, leucine and mixtures thereof to give said improved sow lactation diet, the

TBCAA content of said improved sow lactation diet being sufficient to give a TBCAA:lysine ratio from at least about 3.24:1.

12. The method of claim 1 1, wherein at least a portion of said total protein content is derived from a protein source selected from a group consisting of cereal grain and oil seed.

13. The method of claim 11 , wherein said improved diet includes a wheat content of from about 5 to 50% by weight.

14. The method of claim 11 , wherein said improved diet includes a corn content of at least about 10%.

15. The method of claim 11 , wherein said improved diet includes a soybean meal content of at least about 1%.

16. The method of claim 11, wherein said improved diet includes a total lysine content of from about 0.9-1.2% by weight.

17. The method of claim 11 , wherein said improved diet includes a total isoleucine content of at least about 0.75% by weight.

18. The method of claim 11 , wherein said improved diet includes a total leucine content of at least about 1.35% by weight.

19. The method of claim 11 , wherein said improved diet includes a total valine content of at least about 0.72% by weight.

20. The method of claim 11 , wherein said improved diet includes at least about 0.1% by weight of synthetic branched chain amino acid(s) selected from the group consisting of isoleucine, leucine and mixtures thereof.

21. A method of feeding lactating sows including the steps of feeding to said sows a sow lactation diet comprising a total protein content of from about 12 to 30% by weight, a total lysine content of at least about 0.9% by weight, and a TBCAA content sufficient to give a TBC AA:lysine ratio of at least 3.24: 1 , wherein said TBCAA content includes at least about 0.05% by weight of synthetic branched chain amino acid(s) selected from the group consisting of isoleucine, leucine and mixtures thereof.

22. The method of claim 21 , wherein at least a portion of said total protein content is derived from a protein source selected from a group consisting of cereal grain and oil seed.

23. The method of claim 21, wherein said diet includes a wheat content of from about 5 to 50% by weight.

24. The method of claim 21, wherein said diet includes a corn content of at least about 10%.

25. The method of claim 21, wherein said diet includes a soybean meal content of at least about 1%.

26. The method of claim 21 , wherein said diet includes a total lysine content of from about 0.9-1.2% by weight.

27. The method of claim 21, wherein said diet includes a total isoleucine content of at least about 0.75% by weight.

28. The method of claim 21, wherein said diet includes a total leucine content of at least about 1.35% by weight.

29. The method of claim 21 , wherein said diet includes a total valine content of at least about 0.72% by weight.

30. The method of claim 21 , wherein said diet includes at least about 0.1% by weight of synthetic branched chain amino acid(s) selected from the group consisting of isoleucine, leucine and mixtures thereof.