By Andersen, B. B. and Korver, S. and Oldham, J. and Ostergaard, V. and Solbu, H. and Wiktorsson, H., Livestock Production Science, 1990
Description
This report by the working group set up by the Commission on Animal Genetics and the Commission on Animal Nutrition of the European Association of Animal Production gives the definitions of efficiency for primary and secondary traits in dairy cattle which can be used in the design of breeding programmes and plans for feeding strategies. The primary traits relate to milk, feed and beef. For milk, a definition is given for energy-corrected milk yield per day. For feed, definitions are given for residual feed intake, feed efficiency and voluntary feed intake. For beef, definitions are given for gain per day, dressing percentage, grading, and energy consumed per kg of product. The secondary traits include reproduction, health and "workability". The traits considered for reproduction are non-return percentage, days open and calving interval, those for health are mastitis incidence, calving difficulty, ketosis and laminitis, and those for workability are milking ability and temperament. Also, a definition is given for overall economic efficiency. The report concludes as follows. "The improvement in biological efficiency is important, and research has to be focussed on the underlying processes such as rumen function, utilisation of digested and metabolised energy, and the partitioning of feed energy between milk and body tissue. Knowledge about genetic variation between animals for these different biological processes is very limited, and should be studied in relation to the composition of feed ration, the feeding strategy and the physiological state of the animal". Single-trait selection for milk yield has had a negative effect on feed efficiency, reproduction and health, and the feed intake capacity has not kept pace with the requirements of high milk yields. As a result, the net income per kg milk has decreased. It is essential to include secondary traits in dairy cattle breeding programmes
This report by the working group set up by the Commission on Animal Genetics and the Commission on Animal Nutrition of the European Association of Animal Production gives the definitions of efficiency for primary and secondary traits in dairy cattle which can be used in the design of breeding programmes and plans for feeding strategies. The primary traits relate to milk, feed and beef. For milk, a definition is given for energy-corrected milk yield per day. For feed, definitions are given for residual feed intake, feed efficiency and voluntary feed intake. For beef, definitions are given for gain per day, dressing percentage, grading, and energy consumed per kg of product. The secondary traits include reproduction, health and "workability". The traits considered for reproduction are non-return percentage, days open and calving interval, those for health are mastitis incidence, calving difficulty, ketosis and laminitis, and those for workability are milking ability and temperament. Also, a definition is given for overall economic efficiency. The report concludes as follows. "The improvement in biological efficiency is important, and research has to be focussed on the underlying processes such as rumen function, utilisation of digested and metabolised energy, and the partitioning of feed energy between milk and body tissue. Knowledge about genetic variation between animals for these different biological processes is very limited, and should be studied in relation to the composition of feed ration, the feeding strategy and the physiological state of the animal". Single-trait selection for milk yield has had a negative effect on feed efficiency, reproduction and health, and the feed intake capacity has not kept pace with the requirements of high milk yields. As a result, the net income per kg milk has decreased. It is essential to include secondary traits in dairy cattle breeding programmes
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