REGULAR ARTICLES Variability in residual feed intake and nutrient utilization in Murrah buffalo heifers Tegene Negesse 1 & Chander Datt 2 & S. S. Kundu 2 Received: 24 March 2016 /Accepted: 16 August 2016 # Springer Science+Business Media Dordrecht 2016 Abstract 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. Keywords Nutrient efficiency . Nutrient retention . Predictability of performance . Selection of animals Introduction Reduced productivity of livestock in India is mainly caused by scarcity of feed which demands improvement in feed efficien- cy. As over 65 % of the total feed requirements in cowherd and beef production is used for maintenance (Arthur et al. 2001, Ferrell and Jenkins, 1985; NRC, 2000), improving feed efficiency improves profitability and economic impact (Gibb and McAllister, 1999). Gross efficiency (GE) is the ratio between feed inputs and production outputs such as feed intake to live weight gain. While GE is a useful measure for nutritional studies in uniform genotypes (Salmon et al. 1990), however, it favors genotypes with high growth rates where over 50 % of the feed is used for maintenance (Montano- Bermudez et al. 1990), and maintenance requirement at maturity is not accounted for by GE. An alternative measure of feed efficiency is residual feed intake (RFI) or net feed efficiency (Koch et al. 1963) that is defined as the difference between actual feed intake and its expected maintenance and growth feed re- quirements. Residual feed intake would be an improved measure of feed efficiency due to its independence from BW and BWG (Koch et al. 1963). Herd and Bishop ( 2000) demonstrated adequate potential for selection against RFI to improve FCR and efficiency of mainte- nance energy expenditure. With the heritability of RFI varying between 0.29 and 0.46, selection for low RFI has added advantages of improving feed conversion ratio, calf-weight-per-cow feed intake, with no ef- fect on average daily gain or mature size or efficiency of adult cattle and progeny (Archer et al. 1998). This research work was therefore planned to determine the RFI of growing Murrah buffalo heifers and investigate its association with feed intake and nutrient balance. * Tegene Negesse tegenengss38@gmail.com 1 Hawassa University, Hawassa P. O. Box 336, Ethiopia 2 National Dairy Research Institute, Karnal, Haryana 132001, India Trop Anim Health Prod DOI 10.1007/s11250-016-1130-6