Date of this Version
Four trials were conducted with 1,480 pigs (initial wt: 23 kg in trial 1, 29 kg in trial 2 and 49 kg in trial 3 and 4) to determine the effect of dietary fat on pig performance, nutrient separation in an automated feed distribution system, dust levels in swine buildings and integrity of the respiratory system of swine. Two modified-open-front (B-1 and B-2) and two environmentally regulated (E-1 and E-2) growing-finishing buildings, of identical design, were used in each trial. In trial 1,250 pigs (25 pens of 10 pigs/pen) in B-1 were fed a ground, mixed, corn-soybean meal diet (15% crude protein) with added tallow (5%), and 250 pigs in B-2 were fed the same diet but without added tallow. The assignment of diets to buildings were reversed in trial 2 in which 2.5% tallow was used instead of 5%. Each diet was fed ad libitum to pigs, and was distributed by an automated "Flexauger" system in trials 1 and 2. In each of trials 3 and 4, 120 pigs (12 pens of 10 pigs/pen) in E-1 were fed a corn-soybean meal diet (14% crude protein) with added tallow (5%) and 120 pigs in E-2 were fed the same diet but without added tallow. Overall, pigs fed the diet with tallow gained faster (P<.O02), consumed less feed (P<.02) and converted feed more efficiently (P<.OO2) than those fed the diet without tallow in trials 1 and 2. Pig performance was also improved by the addition of tallow to the diet in trims 3 and 4 (P<.O02). Crude protein, Ca, P and Ca contents of both diets were similar at each location sampled throughout the automated distribution system in trials 1 and 2. Addition of tallow to the diets reduced aerial dust levels, both with the feed distribution auger running (P<.002) and without the auger running (P=.06) in trials 1 and 2. In trials 3 and 4, adding 5% tallow to the diet reduced aerial dust concentrations of particle sizes of 14, 4, and 1.5 Wm (P<.O02) and .4/~m (P=.07). The amount of settled dust was lower (P<.O01, trials 1, 3 and 4) when tallow was included in the diet. There was no difference between the two dietary treatments in the incidence of abnormal turbinates in all four trials. There was a trend for pigs fed the diet without tallow to have more severe forms of lung lesions than those fed the diet with tallow in trials 1 and 3. The results of microscopic examination and crude protein analysis of settled dust indicated that the swine-house dust was mainly feed dust.