Variability in residual feed intake and nutrient utilization in Murrah buffalo heifers

A feeding trial with 18 Murrah buffalo heifers (238 +/- 63 kg; 1.7 +/- 0.4 years old) was conducted for 57 days, and feed intake and body weight were recorded followed by 7 days of urine and feces collection. Heifers were grouped into low (RFI-I) and high (RFI-II) feed efficiency groups by regressing DMI (g head(-1) day(-1)) on BWG (g head(-1) day(-1)) and mid-test MBW (kg). RFI-II heifers had slightly higher DMI (g head(-1) day(-1) and expressed per unit of BW, %BW, MBW, mid-test BW, and mid-test MBW) and all associated nutrient intakes, BWG, feed efficiency traits (FCR, CPCR), digestibility of nutrients, and retentions of crude protein and fat over RFI-I heifers. The corresponding intake values (kg head(-1) day(-1)) for RFI-I versus RFI-II were the following: DMI (6.73 +/- 0.56 vs 6.51 +/- 0.50), CPI (0.99 +/- 0.008 vs 0.97 +/- 0.07), DOMI (5.06 +/- 0.47 vs 5.11 +/- 0.42), and TDNI (4.95 +/- 0.47 vs 5.00 +/- 0.42). BWG (669 +/- 52 vs 776 +/- 47 g head(-1) day(-1)), feed efficiency traits (FCR: 10.32 +/- 1.16 vs 8.77 +/- 1.04 and CPCR: 1.52 +/- 0.17 vs 1.30 +/- 0.16), N balance (38 +/- 9 vs 45 +/- 8 g N head(-1) day(-1)), and protein and fat retentions (239 +/- 57 vs 282 +/- 51 g CP head(-1) day(-1) and 430 +/- 6 vs 494 +/- 59 g fat head(-1) day(-1)) of RFI-I were less than RFI-II heifers, respectively. Based on the predicted RFI values, RFI-II buffalo heifers could be selected for feed efficiency.