Effect of Season on Growth Performance of Finishing Pigs fed Low-Protein, Amino Acid Supplemented Diets

摘要

Myer, R.O., Brendemuhl, J.H. and Bucklin, R.A. 2008. Effect of season on growth performance of finishing pigs fed low-protein, amino acid supplemented diets. J. Appl. Anim. Res., 34: 1?￠????8. A two year study was conducted to evaluate the effects of diet (low-protein diets supplemented with crystalline amino acids (aa) vs. high-protein, non aa supplemented control diets) and season/rearing environment (hot, humid summer vs. cool fall/winter) on growth performance and carcass lean content of finishing pigs (52 to 110 kg). For each year, two trials, each with 84 pigs, were conducted. Outside daily high and low temperatures (C) and RH (%), respectively, averaged 26, 21 and 81; 26, 20 and 83; 14, 7 and 80; and 10, 3 and77for yr 1 and 2 summer and y r 1 and 2 fall I winter, respectively. Diets were maize and soybean meal based (3.3 meal ME/kg). The low-protein (LP) diets were four percentage units lower in crude protein (CP) than the corresponding control diets; crystalline lysine, threonine, tryptophan and methionine were added to the LP diets to meet the pigs' requirements (NRC, 1998). For each trial, split sex Finisher I (52 to 82 kg), and Finisher II (82 to 110 kg), diets were fed. Each dietary treatment was fed to six pens of seven pigs for each trial. Water sprinklers were used during warm weather (>25C). Floor space was 0.7m 2 per pig. Pigs reared during the summer grew 9% slower than pigs reared during the fall/winter (0.88 vs. 0.97 kg/d, P<0.001); average daily feed intake (ADF) and feed conversion efficiency (F/G) were also affected by season (P<0.001). Pigs fed the LP + aa diets averaged 3% lower ADG than pigs fed the control diets (0.91 vs. 0.94 kg; P<0.01); ADF and F/G were not affected (P>0.10). The decrease in ADG was more pronounced during the summer vs. fall/winter (6% vs. 1%; season ???? diet, p = 0.02). The decrease noted occurred only during Finisher II (0.91 vs. 0.84 kg/d; P<0.001; FI, 0.97 vs. 0.98). Estimated carcass lean was not affected by diet or season (mean = 51% fat free). The feeding of a LP + aa diet used appears to be of no particular benefit on improving pig growth performance from 52 to 110 kg under hot and humid conditions.