Effect of dietary methionine-to-lysine ratio on lactation performance of first- and second-parity Yorkshire and Hampshire lean genotype sows

Transcription

1 Effect of dietary methionine-to-lysine ratio on lactation performance of first- and second-parity Yorkshire and Hampshire lean genotype sows R. R. Grandhi Agriculture and Agri-Food Canada, Brandon Research Centre, P.O. Box 1000A, Brandon, Manitoba, Canada R7A 5Y3 ( Received 7 May 2001, accepted 21 December Grandhi, R. R Effect of dietary methionine-to-lysine ratio on lactation performance of first- and second-parity Yorkshire and Hampshire lean genotype sows. Can. J. Anim. Sci. 82: A total of 196 Yorkshire (Y) sows, 137 of first and 59 of second parity, and 97 Hampshire (H) sows, 55 of first and 42 of second parity, were used to determine the effect of increased dietary amino acids and two methionine-to-lysine ratios on sow lactation performance. The three treatment diets were: (1) a barley-wheat-soybean meal diet containing lysine at 0.43 g MJ 1 DE with no supplemental amino acids, 2) the same as diet 1, except the lysine content was increased to 0.68 g MJ 1 DE with supplemental threonine and methionine providing threonine and methionine to lysine ratios of 0.60 and 0.26, respectively, and 3) the same as diet 2, except with an increased methionine-to-lysine ratio of All diets were fed as pellets, ad libitum in self-feeders, with free access to drinking water during a 28-d lactation period. Nursing piglets were given creep feed after 14 d of age. The average daily feed intake increased during lactation, and it was higher (P < 0.05) in the second than the first parity sows. Feeding diets 2 and 3 increased (P < 0.05) sow lactation weight and backfat gains, compared to diet 1 for both breeds. Feeding diet 3 increased (P < 0.05) the sow lactation weight and backfat gains and piglet weight gains in the second parity Y sows, but not H sows. Post-weaning sow weight loss and weaning to estrus interval were not different (P > 0.10) among the diets in both breeds. Feeding diets 2 and 3 decreased (P < 0.05) the serum urea nitrogen concentration in Y sows indicating less amino acid catabolism. The results indicated that a dietary methionine-to-lysine ratio higher than 0.27 was not beneficial in maximizing lactation performance of modern lean genotype sows. Key words: Sows, lactation, ideal amino acid, Yorkshire, Hampshire, piglet Grandhi, R. R Incidence du ratio méthionine/lysine sur la lactation des truies Yorkshire et Hampshire à génotype maigre de premier et de deuxième rang. Can. J. Anim. Sci. 82: Les auteurs ont recouru à 196 truies Yorkshire (Y), soit 137 de premier rang et 59 de deuxième rang, et à 97 truies Hampshire (H), soit 55 de premier rang et 42 de deuxième rang, pour déterminer l incidence d une hausse de la concentration d acides aminés dans le régime et de deux rapports méthionine/lysine sur le rendement des animaux à la lactation. Les trois régimes à l étude étaient les suivants : 1) ration d orge, de blé et de tourteau de soja contenant 0,43 g de lysine par MJ d énergie digestible, sans supplément d acides aminés; 2) même ration mais concentration de 0,68 g de lysine par MJ d énergie digestible avec supplément de thréonine et de méthionine en vue d obtenir un ratio de thréonine/lysine et de méthionine/lysine de 0,60 et de 0,26, respectivement; 3) même ration qu en 2 mais avec ratio méthionine/lysine de 0,30. Les rations ont toutes été servies à satiété sous forme d agglomérés dans des nourrisseurs automatiques. Les animaux avaient librement accès à de l eau pendant la période de lactation qui a duré 28 jours. Les porcelets allaités ont reçu des aliments à la dérobée dès l âge de 14 jours. La prise alimentaire quotidienne moyenne a augmenté durant la lactation et était plus forte (P < 0,05) pour les truies de deuxième rang que celles de premier rang. Les régimes 2 et 3 augmentent (P < 0,05) le poids et l épaisseur du gras dorsal des truies des deux races durant la lactation, mais pas le premier régime. Le régime 3 augmente (P < 0,05) le poids et l épaisseur du gras dorsal des truies en lactation ainsi que le gain de poids des porcelets pour les truies Y de deuxième rang, mais pas les truies H. La perte de poids des truies au sevrage et l intervalle entre le sevrage et la réapparition des chaleurs ne varient pas (P > 0.10) avec le régime, peu importe la race. Les régimes 2 et 3 diminuent (P < 0,05) la concentration d azote uréique dans le sang des truies Y, signe que celles-ci catabolisent moins bien les acides aminés. Les résultats donnent à penser qu un ratio méthionine/lysine de plus de 0,27 ne maximise pas le rendement des truies modernes à génotype maigre durant la lactation. Mots clés: Truies, lactation, composition idéale d acides aminés, Yorkshire, Hampshire, porcelets Inadequate nutrition during the sow lactation period results in decreased milk production and, consequently, lower piglet weight gains and survival (Aherne and Kirkwood 1985; Cole 1990). During a nutritional deficiency, sows can mobilize body reserves of fat and protein for milk production, but an excess depletion of body reserves can cause delayed estrus (King 1987; Yang et al. 1989), poor conception and embryo survival (Grandhi 1992), resulting in reduced sow productivity. Modern lean genotype sows possess a relatively high 173 genetic potential for milk production, and thus require more dietary energy and amino acids than conventional sows to express their potential [National Academy of Sciences - National Research Council (NAS-NRC) 1998]. Since modern lean genotype sows have relatively low body fat and tissue reserves, they are more likely to develop reproductive Abbreviations: DE, digestible energy; ADG, average daily gain; Y, Yorkshire; H, Hampshire

2 174 CANADIAN JOURNAL OF ANIMAL SCIENCE problems when the dietary supply of nutrients is compromised. The latter applies in particular to first parity sows (Noblet and Etienne 1987). Sows used in earlier studies for determining dietary requirements for lysine (Wilkinson et al. 1982), threonine (Lewis and Speer 1975), tryptophan (Lewis and Speer 1974), and methionine (Ganguli et al. 1971) during lactation were not of lean genotype. Moreover, in these studies sows were limit fed during lactation, resulting in a higher sow weight and backfat losses. Pettigrew (1993) and NAS-NRC (1998) provided estimates for the dietary amino acid requirements of lactating sows, considering some body weight loss during lactation and the contribution of amino acids derived from the body tissue mobilization to amino acid needs for milk protein synthesis. However, sow weight losses should be minimized and these weight losses can have considerable implications for dietary amino acid requirements. Knabe et al. (1996) reported that increasing dietary lysine (0.60 to 0.90%) by itself did not maximize sow lactation performance. This is likely due to a deficiency of other amino acids such as threonine, methionine and tryptophan, which are supposed to be present at a ratio of approximately 0.60, 0.26 and 0.18, respectively, to lysine in the sow lactation diet (NAS-NRC 1998). However, few studies have been conducted with modern lean genotype sows to determine requirements for these other amino acids. Chung and Baker (1992) reported that the requirement of dietary sulfur amino acids to lysine increases with liveweight of growing pigs. Schneider et al. (1992) reported that increasing dietary methionine levels from 0.16 to 0.58% decreased lactation weight loss in multiparous sows. Although the sows used in this study were fed ad libitum, the average daily feed intake during the 35 d lactation was low at 4.7 kg, while total sow weight loss during lactation was high at 16.4 kg. The objective of this study was to determine the effect of feeding increased dietary amino acid levels and two dietary methionine-to-lysine ratios (0.30 vs. 0.26) on lactation performance during the first and second parities in Yorkshire and Hampshire lean genotype sows. MATERIALS AND METHODS A total of 196 Yorkshire (Y) sows, 137 of first and 59 of second parity, and 97 Hampshire (H) sows, 55 of first and 42 of second parity, were used. The sows were housed and managed according to the guidelines of the Canadian Council on Animal Care (1993), and the animal use protocol (# 95-05) was approved by the Brandon Research Centre Animal Care Committee. Sows were selected for low backfat thickness for more than six generations (McKay 1990), and were regarded as lean genotype sows. Farrowing of first parity Y sows occurred during January February 1996, and the second parity Y sows during July August For the first parity H sows, farrowing occurred during July August 1996, and during January February 1997, for the second parity farrowing H sows. During gestation, sows were group-housed in pens containing closed unheated shelter, and fed a 14% crude protein containing barley and soybean meal-based gestation diet at 2.0 kg (summer/fall) or 2.5 kg (winter) d 1. The gestation diet met nutrient requirements recommended for gestating sows by NAS-NRC (1988). At approximately 109 d of gestation, sows were moved into a heated confinement building for farrowing, and the farrowing was induced by injecting them on day 112 of gestation with 2 ml of Planate (Coopers Agropharm Inc. Ajax, ON) which provided 175 µg of cloprostenol. The piglet birth weights appeared not adversely affected by inducing farrowing at day 112 of gestation. Litter size was equalized by cross-fostering across treatment groups within 48 h of farrowing. After weaning at approximately 28 d of lactation, the sows were moved into a breeding barn for collection of weaning to estrus interval data using vasectomized boars for detecting estrus. The three lactation treatment diets used were: (1) a barley-wheat-soybean meal diet with lysine at 0.43 g MJ 1 DE as control, (2) same as diet 1, except the lysine content was increased to 0.68 g MJ 1 DE with supplemental threonine and methionine providing threonine and methionine to lysine ratios of 0.60 and 0.26, respectively, as recommended by NRC (1988) and (3) same as diet 2 except with an increased methionine to lysine ratio of 0.30 (Table 1). The methionine to lysine ratio of 0.3 was chosen for diet 3 to prevent any possible reduction of feed intake caused by excess dietary methionine (NAS-NRC 1998). All other nutrients, including vitamins and minerals, met or exceeded the NAS-NRC (1988) recommended levels for lactating sows. The various batches of experimental diets that were used throughout the study were prepared according to the same specifications using the same source of feed ingredients to minimize the variation in diet composition. The diets were pelleted, and fed ad libitum from the day of farrowing until 28 d of lactation. Feed was added to the feed troughs three to four times a day, and the average daily feed intake (disappearance) was estimated at the end of each week of the lactation period. Nursing piglets were given an 18% protein starter diet from 14 d of age to weaning at 28 d of lactation. Sows and piglets were weighed on days 1, 14 and 28 of lactation. Sow backfat thickness was also measured on days 1, 14, and 28 of lactation using an ultrasonic scanner (Renco Lean Metre, Renco Corporation, Minneapolis, MN). Backfat thickness was measured directly above the outside curve of the last rib and 6.5 cm lateral to the spine. Two measurements were taken on each side of the spine, and the average recorded. Blood samples were taken from 48 Y and 48 H first parity sows (eight sows of each breed and each of three diets) on days 1, 14 and 28 of lactation. Blood samples were collected from the conjunctival sinus into serum separation tubes, centrifuged at 2000 g, and serum was stored at 20 C until analyzed for urea N concentration. Other measurements recorded were weaning to estrus interval and post-weaning sow weight loss. Chemical Analyses Dry matter, nitrogen and fat in feed samples were determined according to the methods described by the Association of Official Analytical Chemists (1994). Amino acid concentra-

3 GRANDHI DIETARY IDEAL AMINO ACID RATIOS FOR SOW LACTATION 175 Table 1. Composition of lactation diets used for first and second parity Yorkshire and Hampshire sows Diet z Ingredients (g kg 1 ) Ground barley Ground wheat Soybean meal (48%) Animal fat Calcium carbonate Monocalcium phosphate Iodized salt Vitamin-trace mineral premix y L-Lysine HCl Nil L-Threonine Nil D,L-Methionine Nil L-Tryptophan Nil Nil 0.1 Total Calculated nutrient levels (dry matter basis) Energy (DE MJ kg 1 ) Crude protein (g kg 1 ) Total calcium (g kg 1 ) Total phosphorus (g kg 1 ) Lysine (g MJ 1 DE) Actual lysine (g MJ 1 DE) x z Diet 1 = barley-wheat-soybean meal lactation diet with lysine at 0.43 g MJ 1 DE as control; Diet 2 = same as diet 1 except the lysine content was increased to 0.68 g MJ 1 DE, with supplemental threonine and methionine providing threonine and methionine to lysine ratios of 0.60 and 0.26, respectively; and Diet 3 = same as diet 2 except with an increased methionine to lysine ratio of y Supplied per kilogram of diet: vitamin A, IU; vitamin D3, 1000 IU, vitamin E, 50 IU; vitamin K, 4.0 mg; vitamin B 12, 20 mcg; thiamin, 2.0 mg; riboflavin, 5.0 mg; niacin, 20.0 mg; pyridoxine, 1.6 mg; calcium pantothenate, 20 mg; folic acid, 6.0 mg; biotin, 0.2 mg; choline chloride, 500 mg; iron, 100 mg; zinc, 100 mg; manganese, 30 mg; copper, 10 mg; iodine, 10 mg and selenium, 0.1 mg. x Based on determined lysine values in Table 2. tions in experimental diets were determined following hydrolysis with 6 N HCl for 24 h at 110 C (Andrews and Balder 1985). Two sets of 48 blood serum samples (16 from each diet group from first parity Y and H sows) were analyzed for urea nitrogen concentration, using a blood urea nitrogen kit # 535 (Sigma Diagnostics, St. Louis, MO. Statistical Analyses The data were analyzed separately for the Y and H sows because they were farrowed at different times of the year. General Linear Models procedure of the SAS Institute, Inc. (1985) was used, and the model was Y ijk = µ + P i + D j + (PD ij ) + e ijk where Y ijk is the performance of the kth sow in ith parity on jth diet, µ is the overall mean performance, P i is the effect of parity, D j is the effect of diet, (PD ij ) is the two-way interaction of parity and diet, and e ijk is the random error. Sow weight at lactation day 1 was used as covariate when it was significant. Significant differences between least square means were determined by probability of difference procedure (PDIFF) at a probability level of P < The average daily sow feed intake during weeks 1 to 4 of the lactation Table 2. Analyzed amino acid composition (g kg 1 ) of the experimental diets on dry matter basis Diet z Essential amino acids Arginine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan y Valine Non-essential amino acids Alanine Aspartic Cystine Glutamic Glycine Proline Serine Tyrosine z Diet 1 = barley-wheat-soybean meal lactation diet with lysine at 0.43 g MJ 1 DE as control; Diet 2 = same as diet 1 except the lysine content was increased to 0.68 g MJ 1 DE, with supplemental threonine and methionine providing threonine and methionine to lysine ratios of 0.60 and 0.26, respectively; and Diet 3 = same as diet 2 except with an increased methionine to lysine ratio of y Tryptophan concentration was calculated (not analyzed). period was analyzed using Repeated Measures Analysis of Variance procedures (SAS Institute, Inc. 1985). The direction of changes in average daily feed intake during weeks 1 to 4 was tested by fitting polynomial contrasts of linear, quadratic and cubic order. The Pearson correlation coefficients were calculated for the relationships for sow gestation weight gain, sow lactation feed intake, weight and backfat changes, as well as piglet weight gains and survival. The least square means for the main effects (parity and diet) are presented in tables, and the significant interactions between parity and diets are discussed in the results section. RESULTS The analyzed lysine to DE ratios and the ratios of analyzed threonine and methionine to lysine were within 3.0% of the intended values in all diets (Tables 1 and 2). The average daily intakes of DE, lysine, threonine and methionine are summarized in Table 3. Sow Feed Intake During Lactation In the Y sows, the average daily feed intake during the first and second weeks of lactation was similar (P > 0.10) between the first and second parity, but it was higher (P < 0.05) in the second than the first parity during the third and fourth weeks of lactation (Table 4). In the H sows, the average daily feed intake was higher in the second than the first parity throughout lactation. The average daily feed intake was similar (P > 0.10) among the diets in both pari-

4 176 CANADIAN JOURNAL OF ANIMAL SCIENCE Table 3. Average daily intake of DE, lysine, threonine and methionine during the 2- and 4-wk lactation periods in first and second parity Yorkshire and Hampshire sows First parity Second parity Diet 1 Diet 2 Diet 3 Diet 1 Diet 2 Diet 3 Yorkshire DE intake (MJ) Week Week Lysine intake (g) Week Week Threonine intake (g) Week Week Methionine intake (g) Week Week Hampshire DE intake (MJ) Week Week Lysine intake (g) Week Week Threonine intake (g) Week Week Methionine intake (g) Week Week z Diet 1 = barley-wheat-soybean meal lactation diet with lysine at 0.43 g MJ 1 DE as control; Diet 2 = same as diet 1 except the lysine content was increased to 0.68 g MJ 1 DE, with supplemental threonine and methionine providing threonine and methionine to lysine ratios of 0.60 and 0.26, respectively; and Diet 3 = same as diet 2 except with an increased methionine to lysine ratio of Sow nutrient intake was calculated from the average daily feed intake, and from the determined values of lysine, threonine and methionine in Table 2. ties of both breeds. Although a significant week effect indicated that the average daily feed intake changed during the lactation period, these changes were similar for all the diets. A significant week parity interaction indicated that the changes in average daily feed intake from week to week were different in the first and second parity sows. The average daily feed intake appeared higher for the H than for the Y sows in the second parity. The analysis of polynomial contrasts indicated that in the Y sows, there was a linear increase of feed intake, which reached the maximum by the second week in the first parity, and by the third week in the second parity. In the H sows, the feed intake gradually increased until the fourth week in the first parity, but in the second parity it reached a maximum by the third week and then decreased by the fourth week. Sow Weight and Backfat Changes During Lactation The Y sows had more gestation weight gain in the second than in the first parity, but in the H sows, it was less in the second than in the first parity (Table 5). The sow weight on lactation day 1 was higher (P < 0.01) in the second than in the first parity of both breeds. The sow weight gains during the 2- and 4-wk lactation periods were also higher in the second than the first parity of both breeds. Feeding diets 2 and 3 increased (P < 0.05) the sow weight gain compared to diet 1 during the 2- and 4-wk lactation periods for both breeds. For the Y sows, an interaction (P < 0.05) between parity and diets for the 2-wk lactation sow weight gain revealed that in the first parity, it was higher (P < 0.05) for diet 2, but not for diet 3, compared to diet 1 ( 0.5, 2.5 and 0.0 kg for diets 1, 2 and 3, respectively). In the second parity, the sow weight gain was higher (P < 0.05) for diet 3, but not for diet 2, compared to diet 1 (3.7, 5.6 and 12.5 kg for diets 1, 2 and 3, respectively). An interaction (P < 0.05) between parity and diets for the Y sows during the 4-wk lactation period revealed that in the first parity, the sow weight gain was higher (P < 0.05) for diets 2 and 3, compared to diet 1 ( 10.5, 0.2 and 2.7 kg for diets 1, 2 and 3, respectively). In the second parity, the sow weight gain was higher (P < 0.05) for diet 3, but not for diet 2, compared to diet 1 (5.9, 7.2 and 16.9 kg for diets 1, 2 and 3, respectively). The lactation sow weight gains for diets 2 and 3 appeared higher in the H than Y sows. The sow backfat thickness on lactation day 1 was similar (P > 0.10) between the first and second parity for both breeds (Table 5). The sow backfat loss during the 2- and 4-wk lactation periods was higher (P < 0.05) in the second than the first parity for both breeds. Feeding diets 2 and 3 increased (P < 0.05) the sow backfat gain during the 4-wk

5 GRANDHI DIETARY IDEAL AMINO ACID RATIOS FOR SOW LACTATION 177 Table 4. Effect of dietary methionine to lysine ratio on average daily feed intake during 1 to 4 wk of lactation period in Yorkshire and Hampshire sows of first and second parity Parity Diet z Pooled P value SEM Parity Diet P D Yorkshire y No of sows Week Week Week Week wk wk Hampshire x No of sows Week Week Week Week wk wk z Diet 1 = barley-wheat-soybean meal lactation diet with lysine at 0.43 g MJ 1 DE as control; Diet 2 = same as diet 1 except the lysine content was increased to 0.68 g MJ 1 DE, with supplemental threonine and methionine providing threonine and methionine to lysine ratios of 0.60 and 0.26, respectively; and Diet 3 = same as diet 2 except with an increased methionine to lysine ratio of y Repeated measures of analysis of variance P value for week effect = < 0.01; week parity effect = < 0.01; week diet effect = Polynomial contrasts: Linear = < 0.01; quadratic = 0.931; cubic = x Repeated measures analysis of variance P value for week effect = 0.032; week parity effect = < 0.01; week diet effect = Polynomial contrasts: Linear = 0.082; quadratic = 0.465; cubic = Table 5. Effect dietary methionine to lysine ratio on sow weight and backfat changes during 2- and 4-wk lactation period in Yorkshire and Hampshire sows of first and second parity Parity Diet z Pooled P value SEM Parity Diet P D Yorkshire No of sows Gestation ADG (kg d 1 ) Sow body weight (kg) Lactation day wk change < a 4.1b 6.2b wk change a 3.7b 7.1b Sow backfat (mm) Lactation day a 13.7a 12.4b wk change < < wk change a 0.4b 0.5b Post weaning ADG (kg) Days to estrus Hampshire No of sows Gestation ADG (kg) Sow body weight (kg) Lactation day wk chang a 6.9b 6.9b wk change a 10.5b 9.8b Sow backfat (mm) Lactation day wk change wk change <0.1a 1.0b 1.3b Post-weaning ADG (kg) Days to estrus z Diet 1 = barley-wheat-soybean meal lactation diet with lysine at 0.43 g MJ 1 DE as control; Diet 2 = same as diet 1 except the lysine content was increased to 0.68 g MJ 1 DE, with supplemental threonine and methionine providing threonine and methionine to lysine ratios of 0.60 and 0.26, respectively; and Diet 3 = same as diet 2 except with an increased methionine to lysine ratio of a, b Least square means for diets followed by different letters are significantly different (P < 0.05).

6 178 CANADIAN JOURNAL OF ANIMAL SCIENCE Table 6. Effect of dietary methionine to lysine ratio on piglet weight gains and survival rate during 2- and 4-wk lactation period in Yorkshire and Hampshire sows of first and second parity Parity Diet z Pooled P-value SEM Parity Diet P D Yorkshire No of sows Piglet weight (kg) Lactation day wk gain (kg) wk gain (kg) a 7.2ab 7.4b Litter weight(kg) No. of piglets Lactation day wk survival (%) wk survival (%) Hampshire No of sows Piglet weight (kg) Lactation day wk gain (kg) wk gain (kg) Litter weight (kg) No. of piglets Lactation day wk survival (%) wk survival (%) z Diet 1 = Barley-wheat-soybean meal lactation diet with lysine at 0.43 g MJ 1 DE as control; Diet 2 = same as diet 1 except the lysine content was increased to 0.68 g MJ 1 DE, with supplemental threonine and methionine providing threonine and methionine to lysine ratios of 0.60 and 0.26, respectively; and Diet 3 = same as diet 2 except with an increased methionine to lysine ratio of 0.30 a, b Least square means for diets followed by different letters are significantly different (P < 0.05). lactation period for both breeds, and the increase was not different (P > 0.10) between diets 2 and 3. In the Y sows, an interaction (P < 0.05) between parity and diets during the 4-wk lactation period revealed that in the first parity, the sow backfat loss was similar (P > 0.10) among the diets ( 1.2, 0.3 and 1.0 mm for diets 1, 2 and 3, respectively), but in the second parity, the sow backfat gain was increased by diet 3, but not for diet 2, compared to diet 1 (0.3, 1.3 and 2.2 mm for diets 1, 2 and 3, respectively). In the H sows, an interaction (P < 0.05) between parity and diets during the 2-wk lactation period revealed that in the first parity, the sow backfat gain was increased by diets 2 and 3, compared to diet 1 ( 0.4, 0.7 and 0.7 mm for diets 1, 2 and 3, respectively), but in the second parity, the backfat gain was similar (P > 0.10) among the diets (1.4, 1.2 and 0.7 mm for diets 1, 2 and 3, respectively). In the Y sows, the post-weaning weight loss until estrus and days to estrus was similar (P > 0.10) between the parities and among the diets (Table 5). An interaction (P < 0.05) between parity and diets for post-weaning weight loss revealed that in the first parity, it was higher (P < 0.05) for diet 2 than for diets 1 and 3 ( 2.7, 3.4 and 3.0 kg for diets 1, 2 and 3, respectively), but in the second parity, it was similar (P > 0.10) among the diets ( 3.9, 3.4 and 4.0 kg for diets 1, 2 and 3, respectively). In the H sows, the post-weaning weight loss was higher (P < 0.05) for the first than the second parity, and it was similar (P > 0.10) among the diets. The days to estrus tended to be lower (P = 0.09) in the second than the first parity sows, and were similar among the diets. Piglet Weight Gains and Survival Rates During Lactation The piglet weights on lactation day 1 were similar (P > 0.10) between the parities and among the diets for both breeds (Table 6). The piglet weight gains were higher (P < 0.05) in the second than in the first parity during the 2-wk lactation period for the Y sows, and during both 2- and 4-wk lactation periods for the H sows. The litter weights were also higher (P < 0.05) in the second than in the first parity for both breeds. In the Y sows, the piglet weight gains were higher (P < 0.05) for diet 3, while they did not differ between diets 2 and 3. The litter weights at the end of 4-wk lactation period were similar among the diets for both breeds. The litter weight appeared higher for Y than the H sows. The piglet survival during the first 2- and 4-wk lactation periods for the Y sows was lower in the second than the first parity, but it was similar (P > 0.10) among the diets for both breeds (Table 6). An interaction (P < 0.05) between parity and diets during the 2-wk lactation period for the Y sows revealed that in the first parity, piglet survival was lowest for diet 2 (96.6, 91.4 and 95.9% for diets 1, 2 and 3, respectively), but in the second parity, piglet survival was highest for diet 2 (88.3, 91.3 and 84.0% for diets 1, 2 and 3, respectively). An interaction (P < 0.05) between parity and diet during the 4-wk lactation period for the Y sows revealed that in the first parity, piglet survival was also lowest for diet 2 (95.8, 91.2 and 96.2% for diets 1, 2 and 3, respectively), but in the second parity, piglet survival was lowest for diet 3 (85.9, 89.4 and 83.0% for diets 1, 2 and 3, respectively).

7 GRANDHI DIETARY IDEAL AMINO ACID RATIOS FOR SOW LACTATION 179 Table 7. Effect of dietary methionine to lysine ratio on serum urea nitrogen concentration (mg dl 1 ) in first parity Yorkshire and Hampshire sows Diet z Pooled P value SEM Diet Yorkshire No. of sows Day Day a 23.7b 20.9b Day a 21.1b 20.5b Hampshire No. of sows Day Day Day z Diet 1 = barley-wheat-soybean meal lactation diet with lysine at 0.43 g MJ 1 DE as control; Diet 2 = same as diet 1 except the lysine content was increased to 0.68 g MJ 1 DE, with supplemental threonine and methionine providing threonine and methionine to lysine ratios of 0.60 and 0.26, respectively; and Diet 3 = same as diet 2 except with an increased methionine to lysine ratio of a, b Least square means in each group followed by different letters are significantly different (P < 0.05). Urea Nitrogen Changes During Lactation In the Y sows, the serum urea nitrogen concentrations appeared low on lactation day 1 compared to lactation days 14 and 28 (Table 7). Feeding diets 2 and 3 decreased (P < 0.05) the urea nitrogen concentrations compared to diet 1 on both 14 and 28-day lactation. In the H sows, the serum urea nitrogen concentrations were not influenced by feeding diets 2 and 3, but they tended (P = 0.09) to be lower for diet 3 than for diet 1 on day 28 of lactation. Relationship between Selected Sow and Piglet Performance Traits In the Y sows of first and second parity, the Pearson correlation coefficients (Table 8) revealed that the gestation weight gain was negatively correlated to sow lactation weight and backfat gain, and sow lactation feed intake. Sow weight on day 1 of lactation was negatively correlated to lactation sow weight gain. Sow lactation weight gain was positively correlated to sow lactation backfat gain and sow feed intake, but it was negatively correlated to litter weight and piglet survival. Sow backfat thickness on lactation day 1 was negatively correlated to sow backfat gain. Sow lactation backfat gain was positively correlated to sow feed intake, but negatively correlated to litter weight in the second parity. In the H sows of first and second parity, the sow lactation weight gain was positively correlated to sow lactation backfat gain and sow lactation feed intake, but it was negatively correlated to litter weight and piglet survival in the first parity. Sow lactation backfat gain was positively correlated to sow lactation feed intake in the second parity, but it was negatively correlated to litter weight and piglet survival in both parities. Table 8. Correlations coefficients of sow and piglet performance traits in Yorkshire and Hampshire sows of first and second parity First party Second party r value P value r value P value Yorkshire sows (N = 196) Sow gestation weight gain vs. lactation Weight gain 0.40 < <0.01 Backfat gain 0.37 < <0.01 Sow feed intake 0.32 < Piglet survival Sow lactation body weight gain vs. lactation Sow weight day Backfat gain 0.74 < <0.01 Sow feed intake 0.57 < Litter weight Piglet survival <0.01 Sow lactation backfat gain vs. lactation Sow backfat day < <0.01 Sow feed intake 0.54 < Litter weight Piglet survival Hampshire sows (N = 97) Sow gestation weight gain vs. lactation Weight gain Backfat gain Sow feed intake Piglet survival Sow lactation body weight gain vs. lactation Sow weight day Backfat gain 0.72 < <0.01 Sow feed intake 0.39 < <0.01 Litter weight Piglet survival Sow lactation backfat gain vs. lactation Sow backfat day Sow feed intake <0.01 Litter weight Piglet survival DISCUSSION The differences in sow gestation weight gains observed between the first and second parity reflect the changes in body energy requirements for maintenance, thermal regulation, etc. under conditions of limit-feeding and outside housing during winter and summer months. Diets 2 and 3 were supplemented with lysine, threonine and methionine only. These diets contained 7.9% less histidine, 17 > 0% less isoleucine and 29.3% less valine than levels recommended by NAS-NRC (1998). Trottier and Easter (1995) reported that increased dietary supplementation of leucine, isoleucine and valine during lactation did not improve the sow lactation performance, and it decreased the sow lactation feed intake. Richert et al. (1996) reported that increasing dietary valine from 0.75 to 1.15% increased the litter weight at day 26 of lactation by only 3.7 kg. The supplementation of these amino acids in sow lactation diets, therefore, may not be economical in view of such low benefits. Observed increases in sow average daily feed intake during the first 3 wk of lactation, and a higher average daily feed intake in the second than the first parity sows, were in agreement with the findings of Koketsu et al. (1996).

8 180 CANADIAN JOURNAL OF ANIMAL SCIENCE Eastham et al. (1988) suggested that an average daily feed intake of 8.0 kg or more during lactation will increase or maintain the sow backfat levels, but such a high level of daily feed intake may not be physically possible in first parity sows. In the present study, the daily feed intake reached 8.0 kg during the later part of lactation for the second parity H sows. Increased sow lactation weight and backfat gains observed for diets 2 and 3, which contained higher dietary amino acid levels, were in agreement with our previous findings (Grandhi 1997). Sauber et al. (1998) reported that in high lean genotype sows, increasing daily lysine intake from 27 to 62 g improved the lactation performance, while this response depended on an adequate dietary energy intake. Dourmad et al. (1998) reported that high-yielding sows required about 55 g of lysine intake per day for optimum lactation performance. Touchette et al. (1998a) reported that a daily intake of 54 g of lysine was required to minimize sow weight and body protein loss during lactation. In the present study, the average daily intake of DE, lysine, threonine and methionine for diets 2 and 3 during lactation met or exceeded the levels recommended by NAS-NRC (1998) for the lean genotype sows. The sow lactation weight and backfat gains observed for diets 2 and 3 in the present study were higher than the values reported in the above studies. O Grady and Hanrahan (1975) reported that the extent of sow weight loss during lactation was related to the amount of lysine in the diet, but there was no response in weight loss when sulfur amino acids were greater than 0.39% of the diet. Schneider et al. (1992) reported that a daily intake of 17 g methionine decreased the sow lactation weight loss in multiparous sows. In the present study, the daily methionine intake during lactation for diets 2 vs. 3 was 17 vs. 21 g in the Y sows and 14 vs. 27 g in the H sows of first and second parity. A higher dietary methionine to lysine ratio of 0.3 was found to increase sow lactation weight and backfat gains only in the second parity Y, but not H sows, indicating possible breed differences in methionine requirement. Piglet weight gains were higher for diet 3 only in the Y, but not in H sows, indicating that breed differences exist in sow lactation response to increased dietary methionine levels and methionine to lysine ratio. Schwarz et al. (1993) reported that a daily intake of 34 g of sulfur-containing amino acids during lactation maximized piglet weight gains. Greater litter weight in the second than the first parity, and also in Y sows compared to H sows, was probably due to increased milk production. Touchette et al. (1998b) reported that higher dietary lysine levels decreased piglet survival, but that increasing dietary threonine, methionine and tryptophan did not influence piglet survival. Such a decrease in piglet survival was not observed in the present study when sows were fed amino acid supplemented diets. A reduction of the serum urea nitrogen concentration as a result of feeding diets with increased amino acid levels indicated less amino acid catabolism only in Y sows, but not in H sows of first parity. This difference in response of urea nitrogen concentration was probably due to differences in amino acid metabolism between Y and H sows. Coma et al. (1996) also reported a decrease of plasma urea nitrogen in sows fed increasing levels of lysine during lactation. Kirchgessner et al. (1993) reported that increased methionine in sow lactation diets resulted in decreased plasma urea nitrogen concentration. In the present study, an increase in the dietary methionine to lysine ratio only tended to decrease the serum urea nitrogen concentration. A negative relationship between sow gestation weight gain and lactation weight and backfat gains and lactation feed intake indicated that increased gestation weight gain was not desirable in Y sows. A positive relationship between sow lactation feed intake and lactation weight and backfat gains indicated that increasing sow feed intake during lactation is critical to minimizing lactation weight and backfat losses, and to improving sow condition during lactation in lean genotype sows. A negative relationship between the sow lactation weight and backfat gains and litter weights indicated that higher litter weights decrease sow lactation weight gains by utilizing a higher proportion of dietary nutrients for milk production. The differences in response of sow lactation performance between parities and breeds to increased dietary amino acids were probably due to differences in milk production and partitioning of nutrients for tissue growth and milk production (Pettigrew et al. 1993). Sauber et al. (1998) reported that high milk-producing lean genotype sows mobilize more body protein and less fat than conventional sows. Lean genotype sows with a high genetic potential for milk production require more dietary amino acids and energy to support lactation performance than conventional sows. CONCLUSIONS A daily intake of lysine at 0.68 g MJ 1 DE with threonine, and methionine at a ratio of 0.60 and 0.27 to lysine, respectively, was found to be adequate for optimum lactation performance in both Y and H lean genotype sows. An increased dietary methionine to lysine ratio of 0.30, however, increased the sow lactation weight and backfat gains and piglet weight gains in the second parity Y sows, but not H sows, indicating possible breed differences in dietary methionine requirement. The results indicate that adequate energy and amino acid nutrition are essential for the present day lean genotype sows to reach their full performance potential. ACKNOWLEDGMENTS The author extends sincere thanks to Lyle Watson and his staff for taking care of experimental animals; Randy Westwood, Gloria Turner and Nadine Thiry for technical help; Ms. L. Armstrong, University of Manitoba for advice on statistical analysis; and Manitoba Pork and Agriculture and Agri-Food Canada Matching Investment Initiatives for financial support of this study. Aherne, F. X. and Kirkwood, R. N Nutrition and sow prolificacy. J. Reprod. Fertil. 33 (Suppl.): Andrews, R. P. and Balder, N. A Amino acid analysis of feed constituents. Sci. Tools 32: Association of Official Analytical Chemists Official methods of analysis of the Association of Official Analytical Chemists. 16th ed. AOAC, Washington, DC.

9 GRANDHI DIETARY IDEAL AMINO ACID RATIOS FOR SOW LACTATION 181 Canadian Council on Animal Care Guide to the care and use of experimental animals. E. D. Olfert, B. M. Cross, and A. A. McWilliam, eds. Vol. 1. 2nd ed. CCAC, Ottawa, ON. Cole, D. J. A Nutritional strategies to optimize production in pigs. J. Reprod. Fert. 40 (Suppl.): Chung, T. K. and Baker, D. H Methionine requirement of pigs between 5 and 20 kilograms body weight. J. Anim. Sci. 70: Coma, J., Zimmerman, D. R. and Carrion, D Lysine requirement of the lactating sow determined by using plasma urea nitrogen as a rapid response criterion. J. Anim. Sci. 74: Dourmad, J. Y., Noblet, J. and Etienne, M Effect of protein and lysine supply on performance, nitrogen balance, and body composition changes of sows during lactation. J. Anim. Sci. 76: Eastham, P. R., Smith, W. C., Whittemore, C. T. and Phillips, P Responses of lactating sows to food level. Anim. Prod. 46: Ganguli, M. C., Speer, V. C., Ewan R. C. and Zimmerman D. R Sulfur amino acid requirement of the lactating sow. J. Anim. Sci. 33: Grandhi, R. R Effect of feeding supplemental fat or lysine during the post-weaning period on the reproductive performance of sows with low or high lactation body weight and fat losses. Can. J. Anim. Sci. 72: Grandhi, R. R Effects of selection for lower back-fat, and increased dietary lysine level to digestible energy with supplemental threonine and methionine on lactation performance of Yorkshire and Hampshire sows. Can. J. Anim. Sci. 77: King, R. H Nutritional anoestrus in young sows. Pig News Info. 8: Kirchgessner, M., Schneider, R., Paulicks, B. R. and Schwarz, F. J Amino acids and urea in the blood plasma of lactating sows with varying dietary methionine supply- 5. Contribution to the requirement of suckling sows for S-containing amino acids. J. Anim. Physiol. Anim. Nutr. 69: Knabe, D. A., Brendemuhl, J. H., Chiba, L. I. and Dove, C. R Supplemental lysine for sows nursing large litters. J. Anim. Sci. 74: Koketsu, Y., Dial, G. D., Pettigrew, J. E., Marsh, W. E. and King, V. I Characterization of feed intake patterns during lactation in commercial swine herds. J. Anim. Sci. 74: Lewis, A. J. and Speer, V. C Tryptophan requirement of the lactating sow. J. Anim. Sci. 38: Lewis, A. J. and Speer, V. C Threonine requirement of the lactating sow. J. Anim. Sci. 40: McKay, R. M Responses to index selection for reduced backfat thickness and increased growth rate in swine. Can. J. Anim. Sci. 70: National Academy of Sciences National Research Council Nutrient requirements of swine. 9th ed. NAS-NRC, Washington, DC. National Academy of Sciences National Research Council Nutrient requirements of swine. 10th ed. NAS-NRC, Washington, DC. Noblet, J. and Etienne, M Metabolic utilization of energy and maintenance requirements in lactating sows. J. Anim. Sci. 64: O Grady, J. F. and Hanrahan, T. J Influence of protein level and amino acid supplementation of diets fed in lactation on the performance of sows and their litters. Ir. J. Agric. Res. 14: Pettigrew, J. E Amino acid nutrition of gestating and lactating sows. Biokyowa Technical Reviews 5. Publ. Nutri-Quest, Inc. Chesterfield, MO. Pettigrew, J. E., McNamara, J. P., Tokach, M. D., King, R. H. and Crooker, B. A Metabolic connections between nutrient intake and lactational performance in the sow. Livest. Prod. Sci. 35: Richert, B. T., Tokach, M. D., Goodband, R. D., Nelssen, J. L., Pettigrew, J. E., Walker, R. D. and Johnston, L. J Valine requirement of the high-producing lactating sow. J. Anim. Sci. 74: SAS Institute, Inc User s guide ed. SAS Institute, Inc., Raleigh, NC. Sauber, T. E., Stahly, T. S., Williams, N. H. and Ewan, B. C Effect of lean growth genotype and dietary amino acid regimen on the lactational performance of sows. J. Anim. Sci. 76: Schneider, R., Kirchgessner, M., Schwarz, F. J. and Paulicks, B. R Feed intake and body weight of suckling sows in dependence of dietary methionine supplementation. 1. Contribution to the requirement of suckling sows for S-containing amino acids. J. Anim. Physiol. Anim. Nutr. 68: Schwarz, F. J., Schneider, R., Paulicks B. R. and Kirchgessner, M Body weight and intake of supplementary feed of suckling piglets in dependence of the dietary methionine supply of the sow. 4. Contribution to the requirement of suckling sows for S- containing amino acids. J. Anim. Physiol. Anim. Nutr. 69: Touchette, K. J., Alle, G. L., Newcomb, M. D. and Boyd, R. D. 1998a. The lysine requirement of lactating primiparous sows. J. Anim. Sci. 76: Touchette, K. J., Alle, G. L., Newcomb, M. D. and Boyd, R. D. 1998b. The use of synthetic lysine in the diet of lactating sows. J. Anim. Sci. 76: Trottier, N. L. and Easter, R. A Dietary and plasma branched-chain amino acids in relation to tryptophan: Effect on voluntary feed intake and lactation metabolism in the primiparous sow. J. 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