Change in body condition of Gobra zebu cattle under different level of feeding. Relationship with body lipids and energy

Abstract

Thirty six zebu steers (35 Gobra and 1 Maure), 2.5 years-old on average, were equally alloted in 3 groups fed different crop by-product based diets. For diets 1 and 2, molassed rice straw and molassed millet straw were offered ad libitum as a basal diet while the other ingredients were mixed and given (2.5 kg/animal/d) as supplement 1 and 2, respectively. In diet 3, all ingredients were mixed and given as a compound feed. The energy content was higher in diet 3 (0.83 FU/kg DM) than in diet 1 and 2 which were isoenergetic, 0.65 and 0.63 FU/kg DM, respectively. Animals were group-fed twice daily (at 08.00 and 16.00 h) during 3.5 months. Diets offered and refusals were daily measured. Cattle were monthly weighed, their body condition was scored using 2 scales of 6 (BCS0-5) and 9 (BCS1-9) points, and body lipids and energy were estimated. The level of intake of steers was 101, 94.3, and 148.3 g DM/d/BW0.75 for the 1rst, 2nd and 3 rd groups, respectively. Groups 1 and 2 had average daily gain similar (ADG) (446.7 and 425.5 g BW/animal, respectively) and gain in BCS 0-5 (+0.8 points) and in BCS1-9 (+1.9 points). A spectacular development of the hump was observed in cattle of the 3 rd group which was submitted to the richest diet. They also gained more (P<0.01) weight (AOG : 1012 g BW/animal), BCS0-5 (+1.9 points) and BCS1-9 (+3.5 points) than did the others groups. Increased rate of BW gain resulted in an acceleration of body lipids deposits (22.8 kg in the 3rd group vs 11.5 kg in the 1rst and 11.6 kg in the 2nd group) and in gain in body net energy (936.6 MJ in the 3rd group vs 473.9 MJ in the 1rst and 490.3 MJ in the 2nd groups). Each kg of gain in BW contains on average 264.7 g of lipids and 11.4 MJ of net energy.