Studies on hormonal induction of lactation in cows

Abstract

A trial to induce lactation in cows and heifers using the hormones oestradiol dipropionate or stilboestrol dipropionate in combination with progesterone was conducted.

The experimental animals comprised of six each of heifers and cows divided into three groups of two each of cows and heifers. Natural oestrogen and progesterone were given to animals in the first group at the rate of 0.05 mg and 0.125 mg per kg body weight respectively at 12 hour intervals consecutively for seven days. The animals in the second group received synthetic oestrogen and progesterone at the same dose and for the same duration. The Animals in the third group were given synthetic oestrogen and progesterone at the rate of 0.10 mg and 0.25 mg per kg body weight respectively, on alternate days, during a period of 14 days.

There was considerable udder development in all the animals. The development was more in the animals of group I and III in comparison to those of group II. The heifers exhibited pronounced udder development than the cows.

Lactation commenced within a period of 13-21 days after the first injection in all the animals. The milk yield reached the peak with in period of four to ten weeks. The peak yield varied from 140 ml to 4300 ml. The average milk yield per day in the three groups during the period of the first 60 days was 1766,942 and 1638 ml for group I, II and III respectively. The yield obtained for group I and III was significantly higher than that of group II. The heifers gave better yield than the cows.

The composition and properties of the milk obtained from the induced lactation was compared with those of the milk from normal cows. It was found that on the eighth day onwards there was no significant difference in the composition and properties of milk obtained from the experimental animals as compared to those milk from postpartum cows. In general the milk from the animals of induced lactation had similar qualities to that of the milk from postpartum cows.

The erythrocyte count, haemoglobin concentration and packed cell volume decreased and the plasma protein increased during the treatment as well as the post-treatment periods in comparison to the pre-treatment period.

During the treatment period the animals exhibited symptoms of heat. Normal oestrus was observed in six animals with in 42-57 days from the commencement of lactation. Four of them were inseminated and all of them conceived. The body weight remained unchanged in the cows but the heifers showed a slight decline in body weight.

Both natural and synthetic oestrogen along with progesterone were effective in inducing lactation. Natural oestrogen in combination with progesterone was more effective in short duration treatment. When the synthetic oestrogen along with progesterone was given for a longer period better results were obtained than short duration. The induction was more successful in heifers than in cows. Regaining of the reproductive efficiency in some fo the problem breeders was an added advantages of the technique adopted.