Responses to dietary additions of fiber (alfalfa meal) in growing pigs housed in a cold, warm or hot thermal environment.

Five trials involving 112 individually-penned animals were conducted to determine the effects of dietary fiber additions (0 or 10% dehydrated alfalfa meal) on the rate and efficiency of growth and carcass characteristics of growing pigs housed in a cold (10 C), thermoneutral (22.5 C) or hot (35 C) thermal environment. Cold exposure (10 C) depressed efficiency of feed and energy utilization, carcass length, backfat, cold carcass dressing percentage and percentage lean cuts. Exposure to the hot environment resulted in depressed live weight gains but did not alter the efficiency of feed utilization. Dietary additions of alfalfa meal depressed daily gains by 1, 3 and 5% in pigs housed in the cold, warm and hot environments, respectively, and gain:feed ratios by 1, 7 and 10%. Ingestion of the fibrous alfalfa meal depressed cold carcass dressing percentage in the 10 and 22 C environments as compared with the basal diet. Based on these data, the nutritional value of fibrous feedstuffs (15% total dietary neutral detergent fiber or less) for growing pigs allowed to consume feed ad libitum is greater in animals housed in a moderately cold vs a warm or hot thermal environment.