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Evaluation of a model of the energy system of lactating and pregnant cows

Published online by Cambridge University Press:  02 September 2010

P. J. Broadbent ,
J. H. Topps ,
J. J. Clark  and
J. M. Bruce
P. J. Broadbent
Affiliation:
North of Scotland College of Agriculture, 581 King Street, Aberdeen AB9 1UD
J. H. Topps
Affiliation:
North of Scotland College of Agriculture, 581 King Street, Aberdeen AB9 1UD
J. J. Clark
Affiliation:
Scottish Farm Buildings Investigation Unit, Craibstone, Bucksburn, Aberdeen AB2 9TR
J. M. Bruce
Affiliation:
Scottish Farm Buildings Investigation Unit, Craibstone, Bucksburn, Aberdeen AB2 9TR
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Abstract

1. The model of the energy system of lactating, and pregnant, cows proposed by Bruce, Broadbent and Topps (1984) has been evaluated using data relating to 166 lactations for dairy cows and 48 lactations for beef cows. The cows in both sets of data were subjected to various nutritional and managerial regimes.

2. The discrepancies between observed and predicted values of milk (energy) and live weight were small, both as a proportion of the measured values and total energy intake. For Danish Black and White dairy cows the discrepancies for milk were virtually zero on both bases; those for live weight represented 0·020 of the total energy intake, or an over-prediction by 0·054 in late lactation. For Hereford × British Friesian beef cows, suckled by one or two calves, the discrepancies as a proportion of the total energy intake ranged from 0·005 to 0·051 for milk and 0·001 to 0·063 for live-weight change across the nutritional and managerial regimes.

3. It was concluded that the model of Bruce et al. (1984), which considers genetic potential for milk production and growth, nutritional (energy), reproductive and environmental status, may be used to predict milk yield and live-weight change simultaneously from food (energy) input.

Type
Research Article
Information
Animal Production , Volume 38 , Issue 3 , June 1984 , pp. 363 - 375
Copyright
Copyright © British Society of Animal Science 1984

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References

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