Title:	Relationship between feed efficiency indexes and performance, body measurements, digestibility, energy partitioning, and nitrogen partitioning in pre-weaning dairy heifers.
Authors:	LAGE, C. F. DE A. COELHO, S. G. DINIZ NETO, H. DO C. MALACCO, V. M. R. RODRIGUES, J. P. P. SACRAMENTO, J. P. MACHADO, F. S. PEREIRA, L. G. R. TOMICH, T. R. CAMPOS, M. M.
Affiliation:	Camila Flávia de Assis Lage; Sandra Gesteira Coelho; Hilton do Carmo Diniz Neto; Victor Marco Rocha Malacco; João Paulo Pacheco Rodrigues; João Paulo Sacramento; FERNANDA SAMARINI MACHADO, CNPGL; LUIZ GUSTAVO RIBEIRO PEREIRA, CNPGL; THIERRY RIBEIRO TOMICH, CNPGL; MARIANA MAGALHAES CAMPOS, CNPGL.
Date Issued:	2019
Citation:	Plos One, v. 14, n. 10, article e0223368, 2019.
Description:	The objectives of this study were: 1) to classify animals into groups of high and low feed efficiency using two feed efficiency indexes (Residual feed intake (RFI) and residual feed intake and body weight gain (RIG)), and 2) to evaluate if pre-weaning heifer calves divergent for feed efficiency indexes exhibit differences in performance, body measurements, digestibility, energy partitioning, and nitrogen partitioning. A total of 32 Gyr heifer calves were enrolled in a 63-d trial and classified into two feed efficiency (FE) groups based on RFI and RIG (mean ± 0.5 SD). The groups were classified as high efficiency (HE) RFI (HE RFI, n = 9; HE RIG, n = 10), and low efficiency (LE) RFI (LE RFI, n = 10; LE RIG, n = 11). The remaining animals were classified as intermediate (n = 13 (RFI) and n = 11 (RIG)). HE and LE calves had RFI values of?0.052 and 0.049 kg/d (P < 0.05), respectively. The HE RFI group consumed 8.9% less solid diet than the LE RFI group. HE RFI animals exhibited an increased digestibility of crude protein and ether extract and tended to have greater total dry and organic matter digestibility. LE RFI animals had greater gross energy and nitrogen intake, though greater fecal losses resulted in a tendency to reduce energy and nitrogen use efficiency. HE and LE calves had RIG values of 0.080 and -0.077kg/d (P ? 0.01), respectively. HE RIG animals exhibited greater average daily gain (9.4%), body weight (BW), and heart girth, though HE RIG group exhibited narrower hip width. HE RIG animals tended to have greater ether extract digestibility but greater methane losses (% of gross energy). HE RFI in pre-weaning heifers seems to be related to differences in digestibility. Divergent animals for RIG during the assessed phase appear to differ in body measurements, which may be related to differences in the composition of the gain.
NAL Thesaurus:	Milk Methane Diet Nutrients
Keywords:	Feed efficiency Hip Bioenergetics
DOI:	https://doi.org/10.1371/journal.pone.0223368
Type of Material:	Artigo de periódico
Access:	openAccess
Appears in Collections:	Artigo em periódico indexado (CNPGL)