Effect of pre-pelleting whole corn inclusion on growth performance, processing yield, meat quality, gut microbiome, and digestive organ development at different grow-out phases of broilers.
Type of DegreeMaster's Thesis
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Corn is typically ground before its incorporation into broiler diets. However, grinding is the second most expensive cost center of feed manufacturing after pelleting. Therefore, feeding whole corn can be an alternative to reduce the grinding cost without a negative effect on broiler performance. Since, corn kernel size is often too big to be included in poultry diets without grinding, inclusion of whole corn prior to pelleting can utilize the compressive force of pellet-mill to break down the corn kernel. Furthermore, whole corn inclusion might have some benefits on broiler performance and processing yield similar to whole wheat inclusion. Two experiments were conducted to evaluate the effects of pre-pelleting whole corn inclusion on growth performance, processing yield, meat quality, organ development, and intestinal microbiome of broilers. Both experiments consisted of 4 dietary treatments with 10 replicate pens per treatment and 25 broilers per pen. In the first experiment, treatment diets consisted 0, 2.5, 5, and 7.5% whole corn that replaced ground corn and was provide from 1 to 42 d of age. In the second experiment, whole corn was included as 0, 3, 6, and 9% of the total diet from 14 to 42 d, following a common starter diet fed in crumbled form from 1 to 14 d. In both studies, feed intake and body weight (BW) were determined at 14, 28, 42 d and feed conversion ratio (FCR) were adjusted by adding the weight of the mortality to the BW of live birds. At 43 d, 10 birds/pen were processed for yield determination. Cooking loss and coloration of breast meat fillets were evaluated in each treatment group of broilers during the first experiment after 48 h of water chilling. In addition, two-birds per pen were euthanized by CO2 asphyxiation at 42 d during the second experiment to determine the weight of crop, proventriculus, gizzard, liver and ceca and was expressed as a ratio of total live BW. Intestinal microbiome was analyzed at 42 d during the first experiment, however in the second experiment microbiome was analyzed at 28 d. Data were statistically evaluated using ANOVA test through GLM procedure of SAS and means were separated by Tukey HSD test. In first experiment, 7.5% whole corn inclusion significantly improved FCR from 28 to 42 d of age (P<0.05; 1.94 vs. 2.00). Broilers fed diets with 5% whole corn had higher breast meat yield than broilers fed 7.5% (P<0.05; 29.11 vs. 28.40 %) but was similar to broilers fed diets without whole corn. However, inclusion of whole corn did not influence cooking loss and color of breast meat (P>0.05). In addition, diets with 7.5% whole corn showed a trend towards increased Faecalibacterium (P=0.07) and decreased Lactobacillus (P=0.08) in cecal microbiota compared to 5% whole corn. In second experiment, the inclusion of whole corn did not influence BW, feed consumption, and FCR (P>0.05) from 14 to 42 d of age. However, broilers fed diets with 9% whole corn had higher carcass yield (P<0.05; 77.32 vs 77.86) than birds fed diets without whole corn. In the ileum, relative abundance of obligatory anaerobes decreased when 3% pre-pelleting whole corn was included, followed by a significant increase in diets containing 6 and 9% pre-pelleting whole corn inclusion (P<0.05). The inclusion of whole corn did not influence the relative weight of liver, gizzard, crop, and ceca (P>0.05). However, relative proventriculus weight decreased in birds fed diets with 9% whole corn inclusion compared to birds fed diets with 0% whole corn (P< 0.05; 0.28 vs 0.35%). Results of these studies indicated that up to 5% whole corn can be included in starter feed and 9% in grower and finisher feeds without any negative effect on broiler performance.