Performance of growing pigs fed diets based on processing by-products of maize and wheat
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A total of 112 crossbred (Landrace x Large white) weaned pigs (average initial weight 7+ 0.5 kg) were used in two growth and digestion trials to investigate the effect of feeding diets based on milling by-products of maize and wheat on digestibility of nutrients, growth performance and slaughter characteristics. For the growth experiments which lasted 4 months, dietary treatments were assigned to pen groups of four pigs balanced for ancestry, sex, and body weight in a completely randomized arrangement with four replicates. In the first experiment 48 pigs were assigned to two diets in which maize bran or wheat bran provided the energy source. A third dietary treatment where whole maize grain was used as the energy source was included for comparison. In the second experiment sixty four pigs were fed diets with an energy source in which wheat bran was replaced by wheat pollards at levels of 15, 30, 45 and 60 percent of the pollards. Data were collected on feed intake, and body weight gain. Digestion experiments (14-day duration) were conducted using male pigs after completion of each of the feeding trials to determine apparent digestibility of nitrogen, dry matter and energy. At the end of each experiment two pigs from each pen (1 male and 1 female) were slaughtered and their slaughter characteristics determined. Average daily feed intake, average daily gain, and final body weight were significantly (P<0.05) affected by feeding on maize bran, wheat bran or whole maize. Digestibility of dry matter and crude fibre were significantly higher ((P<0.05) for pigs fed maize bran than those fed wheat bran or whole maize. Crude protein digestibility was higher ((P<0.05) for the pigs on the diet in which bran formed the energy source. Mean weights for carcass, ham, head, trotters, and heart were significantly different across diets. The differences in forearm yield, back fat thickness, carcass length, and weight of liver, lungs, spleen, small intestine and kidney were not significant. Carcass composition at the sixth rib showed significant differences for rib weight, and rib eye muscle. Intramuscular fat, subcutaneous fat and bone weight were not significantly affected by diet. When wheat bran was substituted for wheat pollard in the diet, average daily feed intake, was not different across all diets but average daily gain and efficiency of feed utilization were higher (P<0.05) for the 60% than other levels of substitution. There were no differences in the apparent digestibility coefficients of CP, DM and energy among the diets with different levels of wheat bran and wheat pollard. Digestibility of crude fibre was however higher for animals on diets containing 15 and 30 percent pollard than those in which pollard formed 45 and 60 percent of the diet. The results revealed that feeding growing pigs on wheat bran improved ADG, feed efficiency and carcass yield. Adding wheat pollard to bran at levels of 60% or higher improves performance of growing pigs.