Energy requirements of ewes during late pregnancy and early lactation

Robinson, J.J.

Veterinary Record 106(13): 282-284


ISSN/ISBN: 0042-4900
PMID: 6994330
Accession: 000651373

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Energy and protein requirements for ewes in early lactation are calculated from published data and responses in milk yield to changes in ME and crude protein intake are illustrated. Assuming a dietary ME of 10.5 MJ/kg and efficiency of ME utilization for milk production of 63%, ME intakes necessary to maintain a 70 kg ewe and enable daily milk yields of 1.0-3.5 kg are tabulated, with microbial protein yields estimated at 8.6 g/MJ of ME intake. On this basis a dietary crude protein content of 113 g/kg or 10.8 g/MJ is necessary to provide N requirements for rumen bacteria if 80% of the protein is degradable. Tabulations of the effect on milk yield of restricting feed intake indicate that whereas the ewe can mobilize body fat to maintain the energy cost of milk yield no such compensation is possible in the case of protein, thus inadequate protein/energy intake produces a fall in milk yield rather than in body wt. Implications for formulating rations for ewes are discussed.