Date of Award
12-2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Animal and Veterinary Sciences
Committee Chair/Advisor
Annel K. Greene
Committee Member
William C. Bridges, Jr.
Committee Member
Xiuping Jiang
Committee Member
Brett Lumpkins
Abstract
A feeding trial using 750 male Cobb 500 broilers was conducted using five dietary treatments (T) which were formulated to be isocaloric and isonitrogenous. The control (T1) was a standard all-vegetarian commercial broiler diet. The experimental treatments were: T2 containing rendered poultry meal; T3 containing an increased percentage of rendered poultry meal; T4 containing rendered bovine and porcine meal; and T5 containing rendered bovine and porcine meal at an increased percentage. In the diet formulations, the added fat in T1 was vegetable derived, T2 and T3 fat was poultry derived, and T4 and T5 fat was beef and pork (50:50) derived. To keep the diets isocaloric and isonitrogenous, soybean meal levels were adjusted to accommodate for the rendered animal product levels. The diets were fed in triplicate for a total of 15 pens, with 50 birds per pen.
Feed conversion ratios (FCR) were improved for broilers fed diets containing poultry by-products and blended bovine and porcine meat and bone meal as compared to the control all-vegetarian diet. The results indicated that broilers were comparable in weight gain and body weight. Fat mass was not significantly different across dietary treatments.
Jejunum histopathological analysis of the villus length, crypt depth, and villus to crypt ratio were not significantly different between the all-vegetarian control and the diets containing rendered animal products. Similarly, liver histopathological analysis of the Kupffer cell nodules, cholangiohepatitis, and liver cumulative pathology were not significantly different between the all-vegetarian control and the diets containing rendered animal products. There were no differences in intestinal inflammation markers noted in the jejunum and liver cumulative pathology across treatments.
Foot scoring, DXA analysis, and biomechanical testing were conducted on collected samples on day (D) 42. The all-vegetarian diet fed broilers had no significant difference of footpad dermatitis and lesions than the broilers fed diets containing rendered animal products. The mean bone mineral content was higher at D42 for birds fed the diets T3, T4 and T5 as measured by DXA analysis. Biomechanical testing indicated that the broilers fed rendered animal products required a higher load for bone failure when compared to the all-vegetarian control diet.
Color, tenderness, and texture profile analysis were conducted to evaluate meat quality. D42 samples had no significant differences for color, tenderness, and texture profiles between diets containing rendered animal products and the all-vegetarian control diet.
In the present study, addition of rendered animal by-products to broiler diets improved the feed conversion ratio, caused no negative effect on gut health, improved leg health, and resulted in comparable meat quality. Results of this study indicate that commercial broiler production efficiency could be improved by reformulating broiler diets to replace a portion of soybean meal with rendered animal by-products.
Recommended Citation
Thomas, Alexandra, "Impact of Broiler Diets Containing Rendered Animal By-Products vs. All-Vegetarian Feedstuffs" (2024). All Dissertations. 3830.
https://open.clemson.edu/all_dissertations/3830
