LAUSR

Abstract Positive effects of β-hydroxy β-methyl butyrate (HMB) on reproductive performance, growth rate and health have been reported in both human and animal studies. However, research into its effect on sow and litter performance is limited and the results show inconsistencies. The aim of this work was to determine the effects of HMB supplementation to sows on litter and piglet performance to weaning. A total of 279 (214 Large White × Landrace and 65 Large White × Landrace × Duroc) multiparous sows were used across four experiments. Sows received either a control diet or a diet supplemented with HMB (minimum of 15 mg/kg sow’s body weight) from day 100 of gestation until parturition (ca. day 115). The number of piglets born (total, alive or dead) was not affected by maternal dietary treatments. Feeding sows HMB increased total live born litter weight by 5.0% (P =  0.031) with tendencies for these litters to remain heavier at week one (P =  0.081) and at weaning (P = 0.084). There were tendencies for HMB to increase average piglet weights at birth (P =  0.088), week one (P =  0.088) and at weaning (P =  0.054). In addition, there was a tendency for HMB to increase piglet growth rate from week one to weaning (P =  0.079). The concentration of IgM in colostrum was increased by 9.7% with HMB supplementation (P =  0.029). The concentration of IgG was influenced by an interaction between diet and experiment (P =  0.016) whereby HMB significantly increased the colostrum concentration of IgG in experiment 1, numerically increased IgG concentration in experiment 2, but had no effect in experiment 3. Overall HMB supplementation to sows at a minimum dose of 15 mg/kg body weight for 15 days prior to parturition significantly increased litter weight at birth with tendencies for litters and average piglet weights to remain heavier at weaning. Supplemental HMB significantly increased the concentration of IgM in colostrum with a significant interaction between diet and experiment for IgG concentration.