RESIDUAL FEED INTAKE, FEED INTAKE, PERFORMANCE AND NUTRIENT UTILIZATION IN WEANED BUFFALOES FROM A LIBERAL MILK SYSTEM

In liberal milk systems, buffalo have high weaning weights and reach harvest weight at an early age. A study was carried out to evaluate residual feed intake (RFI) as a feed efficiency selection tool and its relationship with feed intake, nutrient utilization and performance in weaned buffaloes from this system. Two performance tests were conducted with a total of 45 buffaloes (initial weight 288 ± 29 kg and age 293 ± 25 d). All buffaloes were at minimum of 75% Murrah bulls. Growth, feed intake, nutrient digestibility (ND) and ultrasound were measured. RFI was computed as the difference between actual and expected feed intake. Buffaloes were assigned to three RFI groups: high (> 0.12 kg DM/d), low (< -0.12 kg DM/d), and medium (between ± 0.12 kg DM/d) RFI. Stepwise regression analyses were used to evaluate the contribution of ultrasound measurements and ND in explaining the variations in DMI. No differences (P>0.05) were observed for initial and final BW, ADG, relative growth rate (RGR), Kleiber ratio (KR) or ultrasound measurements among RFI groups. Low RFI buffaloes had smaller DMI, greater ND, and better feed conversion (FCR) than high RFI buffaloes. Further analysis demonstrated that 65% of the DMI variation was explained by ADG, 11% by metabolic BW (MBW) and 6% by DM digestibility (DMD). Our results indicate that (1) RFI can be used to identify the most efficient buffaloes, without affecting its growth rate; (2) ultrasound measures were not useful to predict DMI; (3) digestibility traits had impact on DMI prediction.