Nutrition in the reproduction of farm animals.

There is still uncertainty about the earliest stage of development at which nutrition influences an animal's subsequent ability to achieve its genetic potential for reproduction. Prenatal growth retardation caused by feeding ewes on a ration as low as 0.5 times maintenance during early pregnancy had no subsequent detrimental effect on either the natural or gonadotrophin-stimulated ovulation rate of the progeny, leading Parr et al. (1986) to conclude that the embryonic development of the primordial germ cells in the ovary was not permanently affected by undernutrition. Martin & Crenshaw (1989) cite literature which suggests that low-plane feeding during the period of oogenesis in the pig (40 d post mating to 35 d post partum) may suppress subsequent ovulation rate. Although there is some evidence in their own experimental observations that this is so there are opposing nutritional influences on embryo survival leading to no significant effect on litter