EVALUATION OF GROWTH PERFORMANCE, CARCASS CHARACTERISTICS, EATING QUALITY OF MEAT, AND BLOOD BIOCHEMICAL PROFILE OF TWO BROILER STRAINS FED ON COMMERCIAL AND ON-FARM FORMULATED DIETS

Abstract

his study was conducted to evaluate the growth performance, carcass characteristics, eating quality of meat, and blood biochemical profile of two broiler strains fed on commercial and on-farm- formulated diets. The study contained four sections. The first section is based on the evaluation of commercial and farm-formulated broiler feed. In this section, the chemical composition of commercial broiler feeds produced by feed processing and farm-formulated feed was evaluated. For this purpose, a total of eight feed mills located in Bishoftu, Gelan, and Akaki-Kality towns were purposefully selected to collect the broiler starter and finisher phase diet. Moreover, farm-formulated diets were evaluated for chemical analysis. Section two of this study evaluated feed intake, growth performance, and feed conversion efficiency of the two strains of broilers based on the feed manufactured at the processing plant and formulated on the farm. The third section of the study evaluated carcass characteristics and blood biochemical profile. Finally, sensory and instrumental eating qualities of meat in broiler chickens were evaluated. A total of 384 mixed-sex day-old chicks (192 per strain) were randomly assigned to four dietary treatments with four replicates, each consisting of 12 broilers. The experiment was set up as a 2 x 4 factorial design, providing each strain with four diets in a completely randomized design. After 42 days of the experiment, one male and one female of each strain from each pen (eight birds per treatment) were slaughtered for carcass characteristics, hematological, serum, eating quality of meat, and sensory analysis. The data generated in the first part of the study was analyzed using the SPSS software package, version 24, while data generated in the other three sections was analyzed using the General Linear Model procedure in SAS version 9.4. The result of the study showed that there was a significant difference in the chemical compositions of the commercial and farm-formulated diets prepared for the broiler starter and finisher phases. In this study, farm formulation diets contained similar chemical compositions to the commercial broiler diets in both phases. Similarly, the source of the commercial feeds was manufactured based on products produced on the farm (37.5%) and purchased from the market (62.5%). The majority of manufacturers of commercial broiler feed cost more than 3551 Ethiopian birr per quintal. The feed price was higher (62.5%) during the dry compared to the rainy season. The main constraints on feed manufacturers are high prices and low quality of feed ingredients, shortage of land, scarcity of feed to be mixed, and transportation costs. The result of the study in the second section showed that there was a significant difference in the feed efficiency, xiii growth, and feed intake of broilers across all dietary treatments. Broiler-fed commercial diet (T2) exhibited the highest average daily body weight gain compared to other diet treatments. Total feed intake was highest in broilers subjected to a commercial diet (T3) compared to other dietary groups. Furthermore, broilers in T2 demonstrated the best feed conversion ratio in the entire phase. Chicken strain had an effect on the final body weight, body weight change, average daily body weight gain, and feed conversion ratio throughout the study period. Chicken strain by diet interaction significantly (P < 0.05) influenced total feed intake and average daily feed intake of broilers during the starter phase. The study further demonstrated that broilers subjected to a farm-formulated diet (T1) had a similar final body weight and body weight change to those fed on the commercial diet (T4). There was a significant effect of strains on the weight of eviscerate, dress, thigh, drumstick, breast, neck, back, and eviscerate yield percentage, with Cobb 500 showing higher values than Hubbard broilers. The farm-formulated diet (T1) significantly increased the weight of non-edible offal compared to the commercial diets, except for the weight of crops and lungs, which were similar to those in the commercial diet group (T4). The Hubbard strain showed a higher least square mean for packed cell volume than the Cobb-500 strain. Sex was found to have no significant impact on the hematological parameters. The farm-formulated diet (T1) also resulted in a higher marginal return rate than that of the commercial diet (T3) in the Cobb-500 strain. The result showed a significant effect of the diets on color redness, pH, and cooking loss in the breast and thigh meat. The farm-formulated diets (T1) have better water-holding capacity than commercial diets (T2 and T3) for breast meat. The farm- formulated diets (T1) of meat proximate composition are similar to commercial diets (T2, T3, and T4) in the breast and thigh meat of broilers. The meat color redness is better in the Hubbard than in the Cobb-500 in the breast and thigh meat. The dry matter meat proximate composition Cobb-500 is better than Hubbard in the breast and thigh meat. Generally, Cobb 500 strains were better in terms of feed intakes, growth performances, carcass yields, and meat quality than Hubbard broiler strain chickens. Farm-formulated diets made from locally available ingredients were found to be an important feed alternative in comparison to commercial diets concerning feed intake, growth performance, feed efficiency, carcass yield, blood biochemical profile, eating quality of meat, and sensory evaluation of broiler chickens. The feed produced on-farm formulation from locally available feed ingredients can serve as an alternative feed to replace a commercial diet for broiler chickens in the study area.