Effect of birth weight,gender and litter characteristics on summer mortality in lambs of Norwegian breeds |
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Authors: | G. Steinheim L. S. Eikje G. Klemetsdal T. Ådn⊘y |
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Affiliation: | 1. Department of Animal and Aquacultural Sciences , Norwegian University of Life Sciences , P.O. Box 5003, NO-1432, ?s, Norway geir.steinheim@umb.no;3. Department of Animal and Aquacultural Sciences , Norwegian University of Life Sciences , P.O. Box 5003, NO-1432, ?s, Norway |
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Abstract: | Abstract This study describes how birth weight, gender, litter size, and age of dam affect lamb mortality during the summer period, using data on lambs of the breeds Spælsau (N ≈ 110 000) and Norwegian White Sheep (N ≈ 450 000) during 1994 to 2005. A general mixed linear model was used for the analysis. Birth weight affected summer mortality non-proportionally: an increase in weight from very small towards the breed mean strongly deflated mortality risk; weigh increase above breed means had little effect. Male lambs had a higher mortality than females, and lambs born by 12-months-old dams were in greater risk than those having older dams. Increasing litter size resulted in increased mortality. The results are discussed and recommendations for future research, with focus on breeding and genotype by environment interaction effects are made. |
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Keywords: | Lamb survival Norwegian White Sheep Ovis aries Spæl |
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