| dc.description.abstract | Previous studies have shown corn particle size and feed form manipulation influence broiler performance, gizzard development, nutrient utilization, and carcass characteristics. It is well-known that feeding pellets reduces feed wastage, mealtime, selective feeding, and nutrient segregation as well as increasing feed intake, weight gain, and feed efficiency. Prior to pelleting, feed is conditioned by injecting steam to the meal. The rise in temperature and moisture accomplished during feed conditioning reduces bacterial load, improves pellet quality, and increases production rate. However, high conditioning temperatures can negatively affect availability of thermolabile nutrients such as vitamins, amino acids, and exogenous enzymes. In trial 1, the effects of conditioning temperature were evaluated on growth performance, nutrient digestibility, and processing yields of broilers from 15 to 49 d of age. A total of 1,120 Ross x Ross 708 broilers was distributed among 4 treatments with 10 replicates per treatment and 28 birds/pen. Treatments consisted of 4 conditioning temperatures (71, 77, 82, and 88°C). A common starter was fed as crumbles, whereas grower and finisher feeds were fed as whole pellets. Titanium dioxide was added as an indigestible marker (0.5%) during the grower phase from 15 to 28 d to determine nutrient digestibility. Feed intake and BW gain were determined at 14, 28 and 49 d of age and FCR was corrected for mortality. At 50 d of age, 10 birds/pen were processed to determine carcass and parts weight and yield. Increasing conditioning temperature from 71 to 88°C increased (P<0.05) pellet quality and reduced (P<0.05) percentage of fines. Feed intake, BW gain, and FCR were unaffected by conditioning temperatures. Tender weights were heavier (P<0.05) on birds fed diet conditioned at 82°C and lowest at 77°C. Increasing conditioning temperatures from 77 to 82°C caused a reduction (P<0.05) in apparent ileal digestibility of crude protein and ileal digestible energy of 4.88%, and 106 kcal/kg, respectively. A second study was conducted to evaluate the interactive effects of feed form and corn particle size necessary to optimize growth performance, carcass yield, and nutrient utilization of broiler. A factorial arrangement of 3 × 3 consisting of 3 corn particle sizes (750, 1,150 and 1,550 μm) and 3 feed forms (mash, 3- and 4-mm pellets) were provided to broilers from 1 to 39 d. Titanium dioxide (TiO2) was added as an indigestible marker (0.5%) during the finisher phase (27-39 d) to determine nutrient digestibility. Feed intake (FI) and body weight (BW) were determined at 17, 27 and 39 d of age and FCR was corrected for mortality. On d 40, 10 birds per pen were processed to determine carcass and parts weight and yield. Broilers fed 3- and 4-mm pellets had higher BW, FI, and lower FCR (P<0.05) than broilers fed mash diets at 39 d of age. Broilers fed diets with 750 µm corn particle size had higher (P<0.05) BW and FI than broilers fed diets with 1,550 µm corn particle size at 39 d. Feed efficiency at 39 d of age was unaffected by corn particle size. Broilers fed 3 mm pellets had the heaviest (P<0.05) carcass and breast weights, followed by 4 mm pellets and lightest weights exhibited by broilers fed mash diets. Broilers fed diets with 750 µm corn particle size had heavier carcass and breast weights (P<0.05) than broilers fed diets with 1,550 µm. Digestibility of nutrients was enhanced by pelleting particularly when corn particle size increased. These results demonstrated that feed processing parameters such as conditioning temperatures, particle size, and feed form influence feed quality, broiler performance, nutrient digestibility, and carcass characteristics. These parameters ease the feed manufacturing process while simultaneously improving growth performance and increasing meat yield of broilers. | en_US |
