INFLUENCE OF ENVIRONMENTAL-TEMPERATURE ON GROWTH, MUSCLE AND ADIPOSE-TISSUE METABOLISM, AND MEAT QUALITY IN SWINE

An experiment involving 32 individually housed, castrated male pigs was conducted to determine the effects of environmental temperature (12-degrees-C = T12 or 28-degrees-C = T28) on the performance, carcass characteristics, muscle and adipose tissue metabolism, and meat quality of pigs fed to achieve equal rates of weight gain between 8 and 92 kg live weight. The T12 pigs had less muscle (P < .01) and more subcutaneous fat (P < .01) in the ham than did T28 animals. Thyroids and adrenals were heavier (P < .01) in T12 than in T28 pigs. Percentage of type I muscle fibers was higher (P < .01) and fiber cross-sectional areas smaller (P < .01) in semispinalis muscle (SS) of T12 pigs, whereas no effect of temperature was noticed in longissimus muscle (LD). Cold exposure induced a larger increase in oxidative metabolism in SS (+ 30 to 32%, P < .001) than in LD (+ 14 to 17%, P < .10) and an enhanced glycolytic metabolism in LD (P < .05). Lipid concentration was higher in SS of T12 than in that of T28 pigs. Lipogenic enzyme activities and unsaturation of backfat were higher in T12 than in T28 pigs, whereas no effect of temperature was noticed in leaf fat. Cold treatment resulted in a faster postmortem pH decline (P < .01), higher glycolytic potential (P < .01), and lower ultimate pH (P < .01) in LD. The results indicate that 12-degrees-C vs 28-degrees-C induced detrimental effects on growth, ham composition, and muscle and adipose tissue quality.