295 The Effect of Weaning age and Diet Complexity on Nursery Pig Growth Performance and Weight at Market

Abstract

Abstract Changes in weaning age and diet complexity can impact pig growth post-weaning. Weanling gilts and barrows [n = 432 Topigs Duroc X (US York X Landrace)] from the same farrowing group were utilized for a 30 or 35 day growth trial to compare early (EW) versus late weaning (LW) and high or low levels of specialty proteins in nursery diets. Pigs (n = 216) were EW (18 or 19 d, average Age = 18.4 days, average BW = 5.96 kg) and 216 pigs were LW 5 days later (24, 25 or 26 d, average Age = 24.6 d, average BW = 7.50 kg). At weaning pigs were blocked by weaning age, BW, sex and litter, and randomly allotted to 48 pens with 9 pigs/pen. Pigs at each weaning age were fed a High Complexity (HC) or a Low Complexity (LC) diet. The trial was conducted as a 2X2 factorial design: 1) EW+HC; 2) EW+LC; 3) LW+HC; 4) LW+LC. Pigs and feeders were weighed on d 0, 7, 14, 21, 28, and 35 for EW, and on d 0, 7, 14, 21, 28, and 30 for LW. The LW pigs had improved ADG and ADFI from days 0-7, 7-14, 14-21, and the final week of the nursery (P < 0.05). There were no differences in ADG and ADFI from days 21-28 (P > 0.05) between weaning ages. G:F decreased for LW pigs from days 21-28 (P < 0.01) compared with EW pigs; however, for the overall nursery trial LW pigs had increased G:F (P = 0.01). The LW pigs had increased overall nursery ADG vs EW pigs (452.5 g/d vs 400 g/d; P < 0.01). End of nursery BW was greater for LW vs EW pigs (21.70 kg vs 20.74 kg; P = 0.001). When comparing pigs of similar BW at weaning, LW pigs were lighter at end of nursery (20.13 kg vs. 21.66 kg; P < 0.01) but were more feed efficient (P < 0.01) than EW pigs. There was a BW block by weaning age interaction, EW heavy pigs had less ADG compared with LW heavy pigs; however, when comparing light weight pigs, the EW light pigs had improved ADG compared with LW light weight pigs (P = 0.017). The EW pigs were lighter at market (approximately day 146 of age) compared with LW pigs (120.78 vs 124.16 kg; P = 0.014). An interaction between weaning age, nursery diet, and sex (P < 0.07) was observed for market weight, EW barrows fed LC diets were lighter at market (120.77 kg) than EW barrows fed HC diets (126.54 kg). Whereas for LW barrows fed LC had greater market weights (130.04 kg) than LW barrows fed HC diets (127.59 kg). A similar, but non-significant pattern was observed for gilts. Weaning age and feeding pigs the correct diet for their age in the nursery can have a lifelong effect on the pig.