Nutrition and Embryo Loss in Farm Animals

Abstract

The literature on the effects of plane of nutrition on embryo survival in sheep, cattle and pigs is reviewed and evidence presented that extremes of nutrition in early pregnancy are detrimental to the growth and survival of the embryos of all three species. Deficiencies of a wide range of specific nutrients have been implicated in poor reproductive performance but it is only for selenium and vitamin E that the effect appears to operate through a shift in embryo survival. For ruminants, extended periods of feeding on the oestrogenic forages, in particular red clover, and the goitrogenic cruciferous crops reduces fertility and for both there is evidence of an effect on embryo survival. Possible modes of action of nutrition on embryo loss are, in the case of over nutrition, heat stress and, in the case of undernutrition, asynchrony of the embryo with its uterine environment, a disturbance in the amino acid composition of the uterine fluid or a reduction in the availability of glucose. Partial embryo loss not only reduces litter size but in the case of the ewe can result in the birth of lambs that are smaller than would be expected for their litter size.