Protein and energy utilization by ruminants at pasture.

Poppi D.P. and McLennan S.R. (1995) Protein and energy utilization by ruminants at pasture.. Journal of animal science, 73 1: 278-290. doi:10.2527/1995.731278x

Author Poppi D.P.
McLennan S.R.
Title Protein and energy utilization by ruminants at pasture.
Journal name Journal of animal science   Check publisher's open access policy
ISSN 0021-8812
Publication date 1995-01-01
Sub-type Critical review of research, literature review, critical commentary
DOI 10.2527/1995.731278x
Open Access Status Not yet assessed
Volume 73
Issue 1
Start page 278
End page 290
Total pages 13
Language eng
Subject 1103 Clinical Sciences
Abstract Low live weight gain of cattle in the wet season of tropical areas was identified as a major limitation to achieving annual growth rates from tropical pasture systems sufficient to meet new market specifications of young animals of high carcass weight. Both protein and energy are limiting nutrients for growth. Net transfer of feed protein to the intestines is often not complete, and losses occur with grasses and legumes when CP content exceeds 210 g of CP/kg of digestible OM. This protein loss is important because a collation of experimental data indicated that cattle consuming low- and high-quality pasture and silage-based diets all responded to extra protein. The response was less for the higher-quality forage. The role of legumes in supplying this protein was investigated and, unless legumes can increase total DMI by at least 30%, they will not supply sufficient intestinal protein to increase live weight gain by about 300 g/d. The problem with legumes and some grasses is the loss of protein from the rumen, and increasing energy supply to the rumen, either through improved digestibility or energy supplements, is a strategy that could be used to reduce this. Strategies to increase the proportion of escape protein would be successful, but incorporation of lowly degradable protein fractions into legumes may be more difficult because of the level of expression of these protein fractions required for a significant live weight gain response. Cattle entering the wet season usually exhibit compensatory growth and are exposed to high ambient temperatures and often to high humidity. Intestinal protein above that stipulated in feeding standards may be beneficial in these circumstances, and more emphasis should be placed on the ability of legumes to supply protein postruminally. At present the protein delivery capacity of agronomically competitive legumes seems to be inadequate for the higher growth rates required in production systems, and supplements of energy and protein will be needed to achieve these higher targets until new cultivars appear.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
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