HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Freetly, H. C. Articles by Brown-Brandl, T. Search for Related Content PubMed PubMed Citation Articles by Freetly, H. C. Articles by Brown-Brandl, T.

Partitioning of energy during lactation of primiparous beef cows¹

USDA, ARS, US Meat Animal Research Center, Clay Center, NE 68933

² Corresponding author: freetly{at}email.marc.usda.gov

For a beef cow to continue in an annual production cycle, she must rebreed within 3 mo after calving. Malnutrition during this period frequently results in failure of the cow to become pregnant. The energetic needs of the cow are increased by lactation, and additional energy is required for growth of the primiparous cow. Determining energy expenditures during the first 40 to 60 d postpartum is critical to developing feed programs that will allow cows to become pregnant with a second calf. Sixty-seven balance trials were conducted on 25 MARC III cows (4-breed composite: Hereford, Angus, Red Poll, and Pinzgauer) that were between 3 and 53 d in milk. Cows’ BW were 481 ± 4 kg. Metabolizable energy intake ranged from 14.8 to 28.9 Mcal/d. Milk yields ranged from 4.7 to 13.3 kg/d. Recovered energy (RE) increased linearly with increased ME intake. Forty-seven observations were obtained with cows in negative tissue energy (TE) balance, and 20 observations were obtained with cows in positive TE balance. Estimated zero RE from regression analysis of RE on ME intake was 146 kcal of ME/kg of BW^0.75. Efficiency of conversion of ME to lactation energy (LE) was 72%. The efficiency for conversion of ME to TE and the conversion of TE to LE was 78%. Our findings suggest that, even though their milk production is lower, the overall efficiency of energy retention in young beef cows is similar to that of dairy cows.

Key Words: cow • energy • heat production

This article has been cited by other articles:

				H. C. Freetly, J. A. Nienaber, and T. Brown-Brandl Partitioning of energy in pregnant beef cows during nutritionally induced body weight fluctuation J Anim Sci, February 1, 2008; 86(2): 370 - 377. [Abstract] [Full Text] [PDF]

				E. Krol, M. Murphy, and J. R. Speakman Limits to sustained energy intake. X. Effects of fur removal on reproductive performance in laboratory mice J. Exp. Biol., December 1, 2007; 210(23): 4233 - 4243. [Abstract] [Full Text] [PDF]