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The effects of nitrogen and energy supplementation on the voluntary intake and digestion of heather by sheep

Published online by Cambridge University Press:  27 March 2009

J. A. Milne
Affiliation:
Hill Farming Research Organization, Bush Estate, Penicuik, Midlothian EH2Q OPY
Alison Christie
Affiliation:
Hill Farming Research Organization, Bush Estate, Penicuik, Midlothian EH2Q OPY
A. J. F. Russel
Affiliation:
Hill Farming Research Organization, Bush Estate, Penicuik, Midlothian EH2Q OPY

Summary

In three experiments the effects of amount and source of nitrogen and energy supplements, and their frequency of feeding, on the voluntary intake and digestion of winter-quality freeze-stored heather (digestibility of organic matter 45%, N content 1·3%) by Scottish Blackface castrated male sheep were examined. The continuous infusion of 0·5gN/day as urea or casein increased voluntary intake by 29% and digestibility of organic matter by 11 percentage units but higher amounts of N supplement gave no further responses. The continuous infusion of a supplement containing 100 g sucrose/day and 3 g N/day as urea gave similar responses in voluntary intake and digestibility of heather to those obtained when N alone was infused. A reduction in the frequency of feeding of the sucrose: urea supplement reduced the response in intake of digestible OM of heather but intakes of digestible OM were higher when an isocaloric supplement of starch: urea was given at the same frequencies (thrice and once daily). The results are discussed in relation to the use of ruminal NH3 concentrations to assess the responses in voluntary intake to N supplementation and the balance required between the nitrogen and energy in the supplement. I t is concluded that the nitrogen and energy supplements could improve the nutrition of sheep grazing heather moorland in winter.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1979

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