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This Article Full Text (PDF) All Versions of this Article: jas.2007-0758v1 87/5/1814    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Calegare, L. Articles by Lanna, P. D. Search for Related Content PubMed PubMed Citation Articles by Calegare, L. Articles by Lanna, P. D.

Preweaning performance and body composition of calves from straightbred Nellore and Bos taurus x Nellore crosses

L. Calegare^*, M. M. Alencar, I. U. Packer^*, P. R. Leme, C. L. Ferrell and P. D. Lanna^*

^* Department of Animal Production, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, Piracicaba, SP, Brazil , Embrapa, São Carlos, SP, Brazil , Department of Animal Production, FZEA/USP, Pirassununga, SP, Brazil USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933-0166

dplanna{at}esalq.usp.br

Abstract

The objectives were to evaluate preweaning performance, body composition, and efficiency of calves representing straightbred Nellore (NL), F1, and three-breed cross systems. Energy requirements, milk production, and efficiency of 39 cow/calf pairs were recorded from straightbred NL calves from NL cows (10), crossbred (Angus-sired) calves from NL cows (ANL: 9), and crossbred calves (CC; Canchim-sired: Charolais Zebu) from Angus x Nellore (ANL: 10) and Simmental x Nellore (SNL: 10) cows. Cows and respective calves were individually fed from birth to weaning (17 to 190 d postpartum). At 38 d of age, corn silage (7.8% CP, 2.19 Mcal ME/kg DM) was available to calves ad libitum. Milk production at 42, 98, 126, and 180 d postpartum was recorded by weighing calves before and after suckling. The ratio between gross energy and ME of milk was considered 1:0.93. Calves were slaughtered at weaning and the 9-10-11^th-rib section removed for body composition estimation. The ANL calves were lighter (P < 0.01) at birth than CC calves; NL calves were intermediate. At weaning, CC calves were heavier (P = 0.04) than NL and ANL calves (230 ± 5.5 vs. 172 ± 8.1 and 209 ± 8.6 kg, respectively). The ANL calves had greater (371 ± 27; P = 0.01) silage intake than NL calves (270 ± 25) and CC (279 ± 17 Mcal). Milk energy intake was greater for CC calves (970 ± 38; P = 0.005) than NL (670 ± 57) and ANL (743 ± 61). The ANL calves compensated for the lower milk production of NL cows, which supplied less of their energy requirement for growth by increased silage intake. Calves from crossbred cows received a higher proportion of their total energy intake from milk. Crossbred calves had greater (P < 0.03) retained energy (RE = weaning body energy – birth body energy) than NL (388 ± 23 for ANL and 438 ± 15 for CC vs. 312 ± 22 Mcal for NL calves). Percentages of water (P = 0.68) and chemical fat (P = 0.28) were similar among groups (63.7 ± 0.6 and 14.3 ± 0.7 for ANL, 63.1 ± 0.4 and 14.7 ± 0.5 for CC and 63.3 ± 0.6% water and 13.7 ± 0.7% chemical fat of empty BW for NL calves). Energetic efficiency (kcal RE/Mcal ME intake) was similar (P = 0.52) among groups (358 ± 22 for ANL, 355 ± 14 for CC, and 327 ± 22 for NL). Greater weight gains and difference in empty body composition at weaning were not enough to compensate the higher ME intake of crossbreds. In this study, the crossbreeding systems evaluated increased preweaning calf performance, but did not affect gross or energetic calf efficiency.

Key Words: Average daily gain • crossbreeding • energy requirements • retained energy • weaning weight