0
A total of 176 pigs (88 barrows and 88 gilts, average initial BW of 94.8 kg) were used in a 33 d growth assay. Pigs were sorted by sex and ancestry, blocked by weight, and assigned to pens. There were 11 pigs per pen and 4 pens per treatment. The pigs were housed in a finishing facility having 1.83 m x 4.88 m pens with half solid and half slatted concrete flooring. Each pen had a self-feeder and nipple waterer to allow ad libitum consumption of feed and water. All diets had at least 0.8% lysine but with 12, 14, 16, and 18% CP. The diets were corn-soybean meal based, with the soy-bean meal fraction of the diet increased (largely at the expense of corn and synthetic amino acids) to supply greater CP to the diet. Pigs and feeders were weighed at d 0 and 33 to allow calculation of ADG, ADFI, and F/G, and the pigs were killed (average BW of 124.7 kg) so carcass data could be collected.
Increasing CP concentration had no effect (P > 0.20) on ADG, ADFI, F/G and hot carcass weight (HCW). With HCW used as a covariate, there were linear decreases in dressing percentage (P < 0.01) and loin depth at the last rib (P < 0.04) as CP concentration in the diet was increased from 12 to 18%. However, fat thickness at the last rib and percentage carcass lean were not affected (P > 0.34) by CP treatment.
Our results indicate that increasing CP from 12 to 18% in diets for late-finishing pigs does not affect growth performance or carcass leanness but has small negative effects on dressing percentage and loin depth.
S M Williams, J D Hancock, C Feoli, S Issa, and T L Gugle. 2008. Swine Day, Kansas State University. 98-100.
