Increasing dietary valine-to-lysine ratio did not affect litter and sow performance during lactation

Abstract Text: The aim of the current study was to determine the valine requirement of lactating sows weaning more than 12 piglets. A total of 565 sows were randomly allocated to one of six diets with analyzed total Val:Lys at 81.7, 84.4, 87.4, 89.5, 93.7 and 97.0 % (calculated SID Val:Lys at 77.6, 80.2, 83.0, 85.0, and 92.2 %, and 7.1 g SID Lys pr. kg in all diets) from d 2 postpartum when litters were standardized to 14 piglets per sow. The sows were fed 2 times per day until d 10 where after feeding was increased to three times per day. Sow BW, backfat (BF) thickness and litter weight were recorded at d 2 and at weaning (d 26). On a subsample of 12 sows per dietary group blood samples were collected and litter weight recorded weekly. Blood samples were centrifuged for 10 min (1,560 x g) at room temperature before the plasma was analyzed for glucose, lactate, NEFA, creatinine and urea nitrogen. A milk sample was obtained and sows BW and BF registered at d 17.  Prior to milk sampling the litter was removed from the sow for 45 min where after an intramuscular injection with 2 ml oxytocin was given. Milk samples were analyzed for DM, lactose, fat and protein. Statistical analysis was performed using R. Milk composition, feed intake, ADG, BW loss and BF loss was analyzed in a model testing effects of Val:Lys ratio, random effect of block and with BW, BF or litter weight at d 2 as covariate. In the model for blood concentrations effects of day, diet x day, and random effects of sow was also included. Sow feed intake was similar across treatments and averaged 6.1±0.8 kg/d (P=0.66). Milk concentrations of DM (17.4 ± 1.5%, P=0.33), lactose (5.6±0.4%, P=0.05), protein (4.7±0.4%, P=0.90) and fat (7.2±1.3%, P=0.37) were not affected by Val:Lys. On average the sows weaned 12.8±1.2 piglets (P=0.25) with an ADG of the litter from d 2 to weaning of 2.8±1.9 kg/d (P=0.61) with no influence of the dietary treatment. Total loss of BF (3.3±1.9mm, P=0.80) and BW (25.9±13.9, P=0.35) was also not affected by dietary Val:Lys. Plasma concentrations of glucose (P=0.33), lactate (P=0.37), NEFA (P=0.89), urea nitrogen (P=0.20), and creatinine (P=0.42) was not impacted by Val:Lys. In conclusion there was no effects of increasing total dietary Val:Lys above 81.7 % on litter growth and sow metabolism in the current study.

Keywords: Valine, Lactation, Sow