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The response of net milk protein output to metabolisable protein supply in dairy cows

Published online by Cambridge University Press:  20 November 2017

R.J. Mansbridge ,
J.A. Metcalf ,
J.D. Oldham ,
J.S Blake  and
J.R. Newbold
R.J. Mansbridge
Affiliation:
ADAS Bridgets Dairy Research Centre, Martyr Worthy, Winchester, Hampshire SO21 1AP, England
J.A. Metcalf
Affiliation:
Borregaard UK Ltd, Clayton Road, Warrington, Cheshire WA3 6QQ, England
J.D. Oldham
Affiliation:
SAC Bush Estate, Penicuik, Midlothian EH26 0QE, Scotland
J.S Blake
Affiliation:
ADAS Bridgets Dairy Research Centre, Martyr Worthy, Winchester, Hampshire SO21 1AP, England
J.R. Newbold
Affiliation:
BOCM PAULS Ltd, 47 Key Street, Ipswich, IP4 1BX England
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Extract

The UK Metabolisable Protein (MP) system (AFRC, 1993) assumes that MP intake is converted to milk net protein with an efficiency of 0.68 and that MP for maintenance is 2.30*liveweight0.75. Previous work has indicated that the efficiency of MP use for milk production may be too high or that the amount of MP required for maintenance may be too low (Newbold et al, 1994). This experiment was designed to investigate the relationship between MP supply and net protein output in diets of differing MP to Metabolisable Energy (ME) ratios.

Four‘cornerstone’ diets based on grass and maize silage (0.33:0.67 dry matter basis), were formulated to meet ME requirements and either 0.25 above or below MP requirements for either 46 or 24 kg milk/d. A total of 72 multiparous Holstein cows, on average 46 days post calving at the start of the study, were grouped into blocks of 4 cows on the basis of milk energy output in the covariance period. ME and MP requirements for each block of cows were calculated from milk energy and milk protein yield in the covariance period.

Type
Programme
Information
Proceedings of the British Society of Animal Science , Volume 1999 , 1999 , pp. 19
Copyright
Copyright © The British Society of Animal Science 1999

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References

AFRC, 1993 Energy and Protein Requirements of Ruminants. Pub. CAB International, Wallingford Google Scholar
Newbold, J.R., Cottrill, B.R., Mansbridge, R.J., and Blake, J.S. 1994 The effect of metabolisable protein on intake of grass silage and milk protein yield in dairy cows. Animal Production. 58 455A Google Scholar