Effects of dietary energy and amino acid levels on physiological responses and reproductive performance in swine

Abstract

Experiment I. Effects of Various Energy Levels of Gestating Diet in Different Season on Reproductive Performance and Milk Composition of Sows

This experiment was conducted to evaluate the effect of various dietary energy levels of gestating diet in different season on reproductive performance and milk composition of sows. A total of 36 mixed-parity (average = 4.92, range = 3 to 8) sows (F1, Yorkshire × Landrace

Darby, Korea) with an initial body weight (BW) of 218.79 ± 4.74 kg were used for 2ⅹ4 factorial arrangement of treatments in a split-plot design. The season of mating (Summer-July or Winter-January) was regarded as a main plot and the four different dietary energy levels for gestating sows (3,165, 3,265, 3,365 or 3,465 kcal of ME/kg) were subplots. The experimental diets containing different energy levels were provided at 2.4kg daily during gestation but one diet was provided ad libitum regardless of treatments. The lower weight gain from day 0 to 110 of gestation was shown when sows were fed low energy diet (linear response, P<0.05) and sows were mated during winter (season response, P<0.01). Both backfat thickness on day 110 of gestation (linear response, P<0.05) and backfat gains from day 0 to 110 of gestation (linear response, P<0.01) were subsequently shown to be higher when dietary energy level was increased. The changes of backfat thickness during lactation were higher when dietary energy level was increased during gestation (linear response, P<0.01). However, the litter weight, piglet weight and piglet weight gain during the whole lactating period were not significantly different among dietary treatments. In the results of the composition of sow colostrum and milk, feeding diets containing different energy levels and mating sows in different seasons had no detectable effects on contents of fat, lactose, protein and total solid except the ratio of solid-not-fat at day 7 postpartum (season response, P<0.05) and the fatty acid profiles. The contents of myristic, stearic and oleic acid in milk were higher when sows were mated during summer, but palmitoleic acid at day 14 postpartum was lower as dietary energy level was increased (linear response, P<0.05). There was a significant dietary energy levelⅹseason interaction in the content of stearic acid at day 7, resulting in high values when dietary energy level was decreased in sows mated during winter compared with those mated during summer. This experiment demonstrated that reproductive performance of sows was not affected by dietary energy level during gestation when 2.4 kg of diet was provided daily. Consequently, constant dietary energy level can be provided to gestating sows regardless of season when environmental temperature in gestating house can be controlled during winter.

Experiment II. Effects of Dietary Methionine Sources and Supplementation Levels on Body Conditions of Lactating Sows

This experiment was done to evaluate the effect of different dietary methionine sources and supplementation levels on body conditions of lactating sows. A total of 35 mixed-parity (average = 4.86, range = 2 to 6) gestating sows (F1, Yorkshire × Landrace

Darby, Korea) with an initial BW of 235.17 ± 4.05 kg were used in a 3-wk trial and sows were allotted to 1 of 5 treatments based on BW and backfat thickness with 7 replicates by 1 + 2ⅹ2 factorial arrangements. The experimental treatments were divided by methionine sources and levels. Two sources of methionine (DL or L-methionine) and two levels of methionine (0.05 and 0.10%) were supplemented. Basal diet was provided as a control treatment. The experimental diets were formulated based on corn and soybean meal and contained 3,265 kcal of ME/kg, 16.80% crude protein, 1.08% lysine, 0.20% Na, 0.90% Ca, and 0.70% total P, respectively. All other nutrients were met or exceeded the requirements of NRC (1998). There were no significant differences on the body weight and backfat thickness of lactating sows by methionine treatments during lactation. The body weight changes in lactation (day 0 to 21) were affected by the supplementation level of L-methionine, resulting in linear and quadratic responses (P<0.05), and then the detectable effect by the supplementation of DL-methionine was also shown, resulting in linear response (P<0.05). Although there were no significant differences, the changes (day 0 to 21) of backfat thickness showed similar trend numerically with the body weight changes, and then the weaning to estrus interval (WEI) was shortened when L-methionine was supplemented to lactating diets (sources response, P<0.05). Supplementing of methionine to lactating diets did not show improvements of body weight and weight gain of nursery piglets, and voluntary feed intake of lactating sows was not affected either by dietary treatments. The colostrum and milk compositions including milk fat, protein, lactose, total solid and solids-not-fat were not affected by dietary treatments and no differences were found in serum methionine level of piglets in day 21 of lactation. However, when sows were fed diets contained 0.10% DL-methionine, 0.05% or 0.10% L-methionine, higher serum methionine levels were observed compared to those fed control diet (P<0.01), resulting in a linear effect by supplementing DL- and L-methionine (P<0.01). In methionine level of sow milk, the linear increase was found as dietary L-methionine level increased (P<0.05). Consequently, methionine supplementation in lactating diets did not show differences in growth performance of nursery piglets, milk composition and voluntary feed intake of sows regardless of sources and supplementation levels except for body weight changes in gestation, methionine level of serum and milk of lactating sows. The supplementation of L-methionine was more efficient source to reduce body weight loss and to improve the body conditions of lactating sow than that of DL-methionine treatment.

Experiment III. Effects of Dietary Lysine Levels on Growth Performance, Nutrient Digestibility, Blood Profiles, Fecal E.coli Counts and Incidence of Diarrhea in Weaning Pigs

This study was conducted to invesetigate effects of dietary lysine levels on physiological responses, nutrient digestibility, blood profiles, fecal E.coli counts, and incidence of diarrhea in weaning pigs. A total of 128 weaning pigs [(Yorkshire × Landrace) × Duroc] (BW = 7.24 ± 0.03 kg

weaned at day 28 ± 2) were randomly allocated to one of four treatments in a randomized complete block (RCB) design and 8 replicates with 4 pigs per pen. Dietary treatments were divided by the dietary level of lysine

1) N + 0.15% (NRC requirement + 0.15% lysine), 2) N (NRC requirement), 3) N – 0.15% (NRC requirement – 0.15% lysine), 4) N – 0.30% (NRC requirement – 0.30% lysine). The Phase I (0-2nd wk after weaning) diet contained 3,265 kcal of ME/kg and 23.70% crude protein and Phase II (3rd–5th wk after weaning) diet contained 3,265 kcal of ME/kg and 20.90% crude protein, respectively. Diets were provided ad libitum during the whole experimental period. All other nutrients were met or exceeded requirements of NRC (1998). There were no significant differences in ADG, ADFI and G/F ratio of Phase I. However, ADG and G/F ratio at Phase II were slightly decreased as dietary lysine level reduced, resulting in linear (P<0.05) and quadratic responses (P<0.05). When pigs were fed high lysine diets, lower BUN concentration was observed (linear responses at 2nd and 5th wk and quadratic response at 5th wk, P<0.01) and urinary nitrogen (linear response, P<0.05), whereas the nutrient digestibilities of dry matter, crude protein, crude ash, and crude fat were not affected by dietary treatments. When pigs were fed high lysine diets, higher moisture content in feces were found at 2nd wk (P<0.05), fecal E.coli counts at 5th wk (P<0.01), and showed higher incidence of diarrhea (P<0.05) compared with low lysine diets. Consequently, when pigs were fed diet containing 20.9% crude protein, adequate requirement of dietary lysine would approximately 1.15% total lysine/kg. Piglets fed high lysine diets showed higher nitrogen retention, incidence of diarrhea, and fecal E.coli counts relative to those fed low lysine diets.