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ANIMAL PRODUCTION |
* Department of Animal Production, Escola Superior de Agricultura "Luiz de Queiroz," Universidade de São Paulo, Piracicaba, SP, Brazil;
and
Embrapa, São Carlos, SP, Brazil; and
USDA, ARS, US Meat Animal Research Center, Clay Center, NE 68933-0166
2 Corresponding author: dplanna{at}esalq.usp.br
The objectives of this study were to determine if percentage Bos taurus (0 or 50%) of the cow had an effect on ME requirements and milk production, and to compare cow/calf efficiency among 3 mating systems. Metabolizable energy requirements were estimated during a feeding trial that encompassed a gestation and lactation feeding trial for each of 2 groups of cows. Cows were 0 or 50% Bos taurus (100 or 50% Nellore) breed type: Nellore cows (NL; n = 10) mated to Nellore bulls, NL cows (n = 9) mated to Angus bulls, Angus x Nellore (ANL; n = 10) and Simmental x Nellore (SNL; n = 10) cows mated to Canchim (5/8 Charolais 3/8 Zebu) bulls. Cows were individually fed a total mixed diet that contained 11.3% CP and 2.23 Mcal of ME/kg of DM. At 14-d intervals, cows and calves were weighed and the amount of DM was adjusted to keep shrunk BW and BCS of cows constant. Beginning at 38 d of age, corn silage was available to calves ad libitum. Milk production at 42, 98, 126, and 180 d postpartum was measured using the weigh-suckle-weigh technique. At 190 d of age, calves were slaughtered and body composition estimated using 9-10-11th–rib section to obtain energy deposition. Regression of BW change on daily ME intake (MEI) was used to estimate MEI at zero BW change. Increase in percentage Bos taurus had a significant effect on daily ME requirements (Mcal/d) during pregnancy (P < 0.01) and lactation (P < 0.01). Percentage Bos taurus had a positive linear effect on maintenance requirements of pregnant (P = 0.07) and lactating (P < 0.01) cows; during pregnancy, the ME requirements were 91 and 86% of those in lactation (131 ± 3.5 vs. 145 ± 3.4 Mcal·kg–0.75·d–1) for the 0 and 50% B. taurus groups, respectively. The 50% B. taurus cows, ANL and SNL, suckling crossbred calves had greater total MEI (4,319 ± 61 Mcal; P < 0.01) than 0% B. taurus cows suckling NL (3,484 ± 86 Mcal) or ANL calves (3,600 ± 91 Mcal). The 0% B. taurus cows suckling ANL calves were more efficient (45.3 ± 1.6 g/Mcal; P = 0.03) than straightbred NL (35.1 ± 1.5 g/Mcal) and ANL or SNL pairs (41.0 ± 1.0 g/Mcal). Under the conditions of this study, crossbreeding improved cow/ calf efficiency and showed an advantage for cows that have lower energy requirements.
Key Words: breed type • energy requirement • maintenance • milk production
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  L. Calegare, M. M. Alencar, I. U. Packer, P. R. Leme, C. L. Ferrell, and D. P. D. Lanna Preweaning performance and body composition of calves from straightbred Nellore and Bos taurus x Nellore crosses J Anim Sci, May 1, 2009; 87(5): 1814 - 1820. [Abstract] [Full Text] [PDF]
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