Effects of Temperature Stress on Growth Performance and Bacon Quality in Grow-Finish Pigs Housed at Two Densities

¹ Department of Animal Sciences, Purdue University, West Lafayette, IN 47907

^* To whom correspondence should be addressed. E-mail: mlatour{at}purdue.edu.

	Abstract

Managing stressors is essential for optimizing pig growth performance. To determine the effects of temperature and space allocation on growth performance and carcass characteristics, pigs were housed within their thermoneutral zone, 23.9°C, or above their thermoneutral zone, 32.2°C, and provided either 0.93 or 0.66 m²/pig for the final 35 d of the grow-finish period. Individual BW were recorded on d 1, 10, 20, and 30. At exsanguination, carcass measurements and samples of backfat and belly fat were collected. Final BW was decreased (P 0.05) from 113 to 103 kg for pigs housed at 32.2°C. The ADG was reduced (P < 0.05) for pigs housed at 32.2°C pigs (0.89 vs. 0.54) as was gain to feed (G:F; 0.28 vs 0.24). Housing at 0.66 m²/pig resulted in pigs that were lighter (P 0.05), 106 compared with 110 kg, as a result of decreased (P 0.05) ADG from 0.78 to 0.65 and decreased (P 0.05) G:F from 0.275 to 0.255 compared with pigs housed at 0.93 m²/pig. Pigs housed at a greater spatial allocation had elevated (P 0.05) ADFI. The interaction of housing at 32.2°C and decreasing spatial allocation increased (P 0.05) adipose iodine value from 66.8 to 70.4, decreased (P 0.05) the ratio of saturated to unsaturated fatty acids from 0.59 to 0.56, and increased (P 0.05) the omega-6 to -3 ratio from 23.56 to 25.27. Decreased spatial allocation resulted in decreased (P 0.05) belly weights. Though increased temperature did not impact belly weight, it did result in differences in raw and cooked bacon characteristics. The 32.2°C pigs had decreased (P 0.05) raw and cooked slice weights, increased (P 0.05) percent lean of bacon, increased (P 0.05) lean to fat ratio of bacon slices, increased (P 0.05) raw slice scores, and increased (P 0.05) quantity of collagen in belly fat. Some of these changes may have resulted from changes in lipid metabolism. Increasing spatial allocation in the 32.2°C housed pigs decreased fatty acid synthase (P = 0.03) and stearoyl-CoA desaturase-1 (P = 0.08) mRNA expression in adipose tissue. The results from this study demonstrated decreased growth, carcass lipid quality and bacon quality in pigs housed at temperatures above thermoneutral zone; however, increasing housing spacial allocation may be a means to ameliorate the negative impacts of temperature stress.

Key Words: bacon quality, carcass quality , housing density, swine, temperature stress