Effect of nutritional restriction on growth, adaptation physiology and estrous responses in Malpura ewes

The study was conducted to ascertain the effects of nutritional restrictions on growth, physiological adaptability and reproduction in sheep. The experiment was conducted for a period of 35 days covering two estrus cycles in 40 adult Malpura ewes. The animals were randomly divided into four groups of 10 animals each (100%; 80%; 70%; 60% of ad libitum). The ewes were fed a ration consisting of 70% roughage and 30% concentrate. At weekly intervals, physiological responses were recorded and blood samples were also collected. Nutritional restriction of different magnitude (80%; 70%; 60% of ad libitum) altered the growth, physiological adaptability and estrus responses to different extents in Malpura ewes. But the impact was most severe in 60% of ad libitum group. Nutritional restriction to the level of 60% of ad libitum feeding significantly decreased body weight, body condition score, plasma insulin-like growth factor, pulse rate in the morning, respiration rate and pulse rate in the afternoon, plasma glucose, total protein, albumin, total cholesterol, plasma tri-iodo-thyronine and thyroxine, plasma cortisol, plasma estradiol, estrus % and estrus duration, while it significantly increased plasma concentration of growth hormone, hemoglobin, plasma concentration of progesterone and estrus cycle length. The study clearly establishes the effect of different levels of nutrition and its impact on the biological functions necessary to adapt to semi-arid environment. Although, 80%, 70% and 60% groups showed signs of nutritional stress, the effects were more pronounced in 60% ewes. Furthermore, this study clearly establishes the role of various hormones required to adapt to different levels of nutritional stress in Malpura ewes.