The effect of dietary biotin level on the productivity of the female pig
Five experiments were conducted with female pigs to investigate the effects of dietary biotin level on: reproductive performance and hoof integrity over four parities (experiment 1); ovulation rate of the gilt (experiment 2); durability of hoof horn and the phospholipid and neutral lipid profile of perinephric and hoof horn fat (experiments 3 and 4) and milk fat (experiment 5). Experiment 1 showed that changes in reproductive performance and hoof integrity in adult sows occurred when pigs were fed levels of dietary biotin previously considered to have been sufficient to meet the sow's requirements (diet calculated to provide 32µg available biotin/kg). Notably, sows receiving 350µg supplementary biotin/kg returned to oestrus 2.9 ± 1.7 and conceived 6.1 ± 1.4 days sooner than controls (p < 0.05). -The number of lesions/sow increased greatly between 170 days of age and first weaning, at which time the control sows had significantly more lesions/sow (13.45 v 9.79; p < 0.001), but appeared to stabilise in the oldest sows. The production of unsaturated fatty acids in the neutral lipid fraction of the milk increased between early and late lactation in the supplemented but not control sows (p < 0.05) in a sample of sows from control and supplemented treatments respectively (experiment 5). The effects on reproductive performance and the biochemical and physical effects observed in the growing pig indicated that biotin deficiency may produce commercially significant effects prior to the development of symptoms of clinical deficiency. No treatment effects were observed for weight of ovary or number of corpora lutea produced by gilts (experiment 2). Hoof horn durability, measured using a Durometer, was greatest in gilts fed high levels of dietary biotin (experiment 4). The fractionated analyses of the perinephric fat indicated that the relative percentage of C16:0 and C18:0 compared to C16:.1 and C18: 1 increased with greater dietary biotin intake and analyses of hoof horn fat indicated similar trends (experiments 3 and 4).