ANN 121: Applied Animal Nutrition-I (2+1)

GROWTH OF THE FOETUS

• The growth of the foetus is accompanied by the formation of the membranes associated with it, and also by considerable enlargement of the uterus.
• In the early stage of pregnancy the amounts of nutrients deposited in the uterus and mammary gland are small, and it is only in the last third of pregnancy (from the sixth month onwards in cattle) that it becomes necessary to make special provision in the diet for the growth of the foetus.
• Even in the later stages the net energy needed for the growth of the uterus is small in relation to the maintenance requirement of the mother herself, but net requirements for protein and for calcium and phosphorus are quite appreciable in the last stage of pregnancy.

Nutrition of pregnant females and its influence on foetal development

The pregnant females must be offered adequate amounts of energy and other nutrients in order to enable the satisfactory growth and development of the foetus, uterus growth and development and to increase the mother’s bodily reserves needed for milk production following parturition. The growth of the placenta and the increase in uterine fluids occur in early and mid-pregnancy. By the end of the second trimester of pregnancy. placental development is almost complete. On the other hand, 80% of foetal growth occurs in the last trimester of pregnancy. In the last one-third of pregnancy the requirements of the foetus increase rapidly, and a low plane of nutrition at this time will restrict fetal growth.

The foetus also obtains fat and proteins from the mother’s blood across placenta. Deficiencies of individual nutrients in pregnancy must be severe to cause the death of fetuses. Protein and vitamin A are the nutrients most likely to be deficient , although death of foetus through iodine, calcium, riboflavin and pantothenic acid deficiencies have also been observed. Congenital deformities of nutritional origin often arise from vitamin A deficiency, which causes eye and bone malformations in particular. Iodine deficiency causes goiter in the unborn, and in pigs has been observed to result in a complete lack of hair in the young. Hairlessness can also be caused by an inadequate supply of riboflavin during pregnancy. Copper deficiency in the pregnant ewe leads to the condition of swayback in the lambs.