T. More

Effect of water deprivation on feed intake, nutrient digestibility and nitrogen retention in sheep

The problem of sheep grazing in the deserts of Rajasthan is that animals do not get drinking water for 2–3 days at a time. Studies carried out at this Institute, on water deprivation in sheep, have indicated that sheep deprived of water for 72 h did not show any adverse effect on wool yield, in spite of the fact that water deprivation reduced feed intake (More & Sahni, 1972). The present experiment is a part of extensive studies carried out on water deprivation with particular reference to sheep production. The paper describes the influence of water deprivation on nutrient digestibility and nitrogen retention in sheep.

A note on the adaptability of native and cross-bred sheep to hot summer conditions of semi-arid and arid areas

Relative adaptability of Chokla and Rambouillet × Chokla half-breds was compared by observing their responses on exposure to summer stress for 6 days and also under accentuated stress by deprivation of drinking water till the animals lost 30% of their body weight. Responses of both the breed groups were similar on 6 days exposure. Accentuated summer stress resulted in decreased feed intake followed by 15, 26 and 31% loss in body weight on 1st, 2nd and 3rd day of exposure, respectively. Progressive decline in faecal moisture, increase in rectal temperature and decrease in morning respiration rate were also noted in both the breeds while an increase in pulse rate was recorded only in the cross-breds. Increase in respiratory or pulse rate for unit rise in rectal temperature was found to be higher in the cross-breds. On accentuated thermal stress, haematocrit values were higher in the cross-breds and blood potassium concentration was higher in the Chokla while blood glucose decreased in both the groups. Under the conditions of short-term exposure to summer stress the cross-breds maintained homoeothermy as well as the Chokla.

A note on cutaneous loss of potassium in Chokla sheep

The loss of potassium through the cutaneous route was measured in three Chokla rams by balance trial and by washing the animals (ambient temperature 28–33 °C, 28–30 mmHg vapour pressure). The excretion of potassium through urine and faeces was 46·7 and 19·4% of the intake, respectively. The excretion through skin recorded by washing the animals was 29·1% against 33·7% potassium available for excretion through the thermoregulatory route. About 2·56 g potassium was thus excreted through the cutaneous route per day. There was a net retention of 9·8 g sodium/ram/day.