Effect of various levels of standardized ileal digestible branched-chain amino acids on lactating sow and litter performance.

Three hundred and sixty sows were used to investigate the effect of various dietary branched-chain amino acids (BCAA) levels on sow lactation and piglet growth performance. On day 112 ± 1.4 of gestation, sows were blocked by the parity group (P1, P2, P3+) and randomly assigned to 1 of 6 dietary treatments containing various levels of standardized ileal digestible (SID) Leu, Ile, and Val. The experimental diets were formulated to the desired levels of BCAA by replacing cornstarch in a basal diet with l-leucine, l-isoleucine, and l-valine. Dietary BCAA levels relative to SID Lys were 114% or 180% for Leu, 56% or 64% for Ile, and 64% or 120% for Val. Diets were formulated to be isocaloric (3.23 Mcal ME/kg) and met or exceeded all other NRC (2012) essential amino acid and vitamin and mineral recommendations. Sow body weight (BW) and backfat thickness were measured at the time of entry into the farrowing room and at weaning. Piglet litter weights were recorded after cross-fostering and weaning to calculate the litter growth rate. Data were analyzed using generalized linear mixed models with fixed effects of dietary treatment and parity group and a random effect of lactation group. The models were fit using R (v4.4.1; R Core Team, 2024). The sow and her litter were the experimental unit, and results were considered significant if P < 0.05. On average, sows nursed their litters for 21.3 d (P = 0.998). The mean parity by treatment ranged from 3.8 to 3.9 (P = 0.999). After farrowing, the mean sow BW was 220 kg with a range between treatments of 216 to 222 kg (P = 0.523). On average, sows gained 2.3% of their BW (P = 0.740) with an average daily feed intake of 8.74 kg/d (P = 0.903). As expected, sow Leu, Ile, and Val intakes were different across treatments (P ≤ 0.001) and corresponded to the varying dietary levels of BCAA. Sows entered farrowing with an average backfat thickness of 11.50 mm (P = 0.919) and lost 6.5% backfat through lactation (P = 0.880). Sows started the trial with an average of 14.1 piglets/sow (P = 0.967) and weaned 12.7 piglets/sow (P = 0.995) with a piglet ADG of 0.22 kg/d (P = 0.280) and a daily litter growth rate of 2.90 kg/d (P = 0.547). In conclusion, there was no evidence of an effect of the various leucine, isoleucine, and valine levels evaluated in this study on lactating sow and piglet performance.