GROWTH PERFORMANCE, BEEF YIELD, QUALITY AND BIOCHEMICAL BASES FOR TENDERNESS IN BEEF FROM ARSI, HARAR, OGADEN AND F1 JERSEY*HORRO CROSSBRED BULLS FED CORN SILAGE BASED FINISHING DIET

This study was conducted to evaluate the growth performance, carcass characteristics, meat yield, primal meat cuts, meat quality, and some biochemical bases for tenderness of meat from bulls of Arsi, Harar, Jersey*Horro crossbred, and Ogaden cattle breeds finished on corn silage based diet at Beef Cattle Farm, Haramaya University, Ethiopia. A total of 12 bulls of four cattle breeds (i.e. 3 bulls from each breed of Arsi, Harar, Jersey*Horro crossbred, and Ogaden) with 2.0 to 2.5 years were used for the study. Data on growth performance was analysed using the random mixed regression model procedure of the SAS. While for the other data, the General Linear Mixed Model of the Statistical Analysis Software (SAS) 9.4 version was used for analysis. The results of the study revealed that the breed of cattle had a significant (p < 0.05) influence on final live body weight, change in live body weight, and average daily weight gain (ADG). The average final body weight was higher (p < 0.05) for Ogaden (253.22 kg) compared to other experimental cattle breeds. The final body weight was higher (p < 0.05) for Harar (189.89 kg) and Jersey*Horro crossbred (180.33 kg) compared to Arsi (153.89 kg). At the end of the 90 days feeding period, the ADG was higher (p < 0.05) for Harar and Ogaden breeds compared to Jersey*Horro crossbred, and Arsi breed. The overall average hot carcass weight, dressing percentages based on hot carcass weight, and rib eye area were 102.93 kg, 47.61 %, and 8.13 inch2 , respectively. The hot carcass weight and chilled carcass weight of bulls from the Ogaden breed were higher (p < 0.05) compared to other experimental cattle breeds. Dressing percentages based on hot carcass weight were higher (p < 0.05) for the Ogaden and Arsi breeds than that of Harar breed and Jersey*Horro crossbred. The overall weight and percentage of meat yield were 77.52 kg and 77.46%, respectively. The overall average ultimate meat pH was 5.69 and within the range from 5.66 up to 5.73. The average values of meat color at 24 hours post slaughter for lightness (L*), redness (a*), chroma, hue angle, and yellowness (b*) were 35.45, 12.62, 17.43, 40.66, and 12.01, respectively. There was no meat darkness or discoloration xv observed for all experimental cattle breeds. The values of meat color obtained in the present study were within the normal recommended ranges. Meat from all cattle breeds in the present study yielded very tender meat. Breed of cattle influenced the percentage of WHC, with higher (p < 0.05) WHC for Harar and Ogaden breeds compared to Jersey*Horro crossbred and Arsi breed. The proximate composition of meat samples revealed that the overall percentages of water, crude protein, ash, and crude fat were 74.93, 26.60, 1.68, and 6.38, respectively. The overall average values of sarcomere length and the length of myofibril fragmentation in meat were 2.48 µm and 37.41 µm, respectively. The myofibrillar fragmentation length was longer (p < 0.05) for the Harar breed compared to other experimental cattle breeds. Gross net revenue was higher for the Ogaden breed. From the results of the study, it was concluded that the Ogaden, followed by the Harar breed, had shown a higher and better growth performance, meat yield, carcass traits, and most primal meat cuts compared to other experimental cattle breeds. All experimental cattle breeds fed a corn silage-based finishing diet produced good-quality meat. The performance of Ogaden cattle suggests the possibility of using this breed for export purposes. Further studies should be conducted to determine the detailed biochemical basis such as calpain enzymes for meat tenderness.