Haemoglobin type and reproductive performance of sheep grazing oestrogenic pastures

Author:

Walker S. K.,Obst J. M.,Smith D. H.,Hall G. P.,Flavel P. F.,Ponzoni R. W.

Abstract

ABSTRACTThe effect of haemoglobin types A and B on reproductive performance of ewes grazing oestrogenic pastures was studied in four commercial flocks in 1973 and in an additional five in 1974 (a total of nine flocks). The number of ewes lambing per ewe mated differed significantly (P< 0·05) between mating types (male AA × female AA, male AA × female AB, male BB × female AB and male BB × female BB). Differences between mating types in the number of lambs born per ewe exposed to the ram and in the number of lambs weaned per ewe exposed to the ram bordered on significance (0·05<P<0·1). Matings involving BB sires were superior to matings involving AA sires. This finding differs from previously published evidence on this topic. There were no significant differences in lamb mortality or in the number of lambs born per parturition. Reproductive performance did not differ amongst ewe genotypes. Age of dam, farm and year had significant effects on most of the reproductive characteristics studied. Three significant interactions (P<0·05) involving mating type were found: mating type × age on number of ewes lambing per ewe exposed to the ram, mating type × farm on number of lambs born per parturition and mating type × year on lamb mortality. Due to the relatively small differences observed in reproductive performance between mating types it is concluded that selection for haemoglobin type is unlikely to overcome the problem of low reproductive performance in sheep grazing oestrogenic pastures.

Publisher

Cambridge University Press (CUP)

Subject

Animal Science and Zoology

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