PRODUCTION TRAITS IN SHEEP AS AFFECTED BY BREEDS AND ENVIRONMENT

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Abstract
Production records from the Ontario Agricultural College sheep flock collected during the years 1950 to 1960 inclusive were analyzed to determine the effects of breeds (Suffolk, Hampshire, and Southdown), age of dam, year, and type of birth and rearing on three production traits (birth weight, weaning weight, and first fleece weight).Suffolks were superior to Hampshires and Hampshires to Southdowns in all three production traits. The effects of years were large but essentially random except for birth weight which progressively declined with time. Single lambs outweighed twins by 0.93 lb at birth and 7.80 lb at weaning. Lambs from mature ewes were 0.38 lb heavier at birth and 0.88 lb heavier at weaning than were those from 3-year-old ewes, which in turn produced lambs that were 0.34 lb heavier at birth and 3.35 lb heavier at weaning than were those from 2-year-old ewes. Age of dam and type of birth did not substantially influence first fleece weight. The analysis indicates that comparisons among sheep should be made within years. Adjusting birth weights for the effects of age or dam and type of birth and rearing will add further accuracy. Appropriate adjustment factors are given.