Addition of fat to the diets of lactating sows: I. Effects on milk production and composition and carcass composition of the litter at weaning

In Exp. 1 two groups of 18 sows were used to evaluate the effects of supple mental dietary fat on sow and litter performance and milk production and co mposition. Sows were provided ad libitum access to either a corn-soybean me al (control) diet or a similar diet containing 10% tallow. Feed intake, ME intake, and milk yield did not differ (P > .10) between treatments. The per centage of solids in milk was greater (P < .05) for sows fed the tallow die t, due to an increase (P < .05) in the fat and ash content. Compared-with p ercentages of fatty acids in milk of sows fed the control diet, the percent ages of C10:0, C14:0, C16:0, C16:1, and C18:3 fatty acids were lower (P < . 05) and the percentages of C18:0 and C18:1 fatty acids were higher in milk of sows fed tallow diets (P < .05). In Exp. 2, 30 sows were fed diets simil ar to those fed in Exp. 1, and the effects of a tallow diet on pig carcass composition at weaning were determined. Litter size was standardized to 10 pigs. There were no differences (P > .10) in ADFI of sows. Daily ME intake- was greater for sows fed tallow than for control sows during wk 2 (P < .05) , wk 3 (P < .10), and the entire-lactation (P < .05) period. Litter weaning weight was greater (P < .05) for pigs from sows fed tallow diets than for pigs from control sows. Pigs from tallow-fed sows had greater carcass fat w eight and fat percentages (P < .05) and lower water and protein percentages (P < .05). These data indicate that the increased fat content of milk from sows fed tallow diets resulted in an increased weight gain for litters nur sing these sows. The composition of the increased weight:gain is almost exc lusively fat.