The study was conducted to develop a simulated heat stress model for sheep depicting natural environmental conditions and to observe its impact on growth, reproductive performance, physiological adaptability, blood metabolites and endocrine responses in Malpura ewes. The experiment was conducted on 16 adult Malpura ewes for a period of 35 days. The animals were randomly divided into two groups of eight animals each (GI – control, GII – heat stress). The GII ewes were exposed to different temperature at different hours of the day i.e. 38°C at 1000–1100 hours; 40°C at 1100–1200 hours; 42°C at 1200–1300 hours; 43°C at 1300–1400 hours; 44°C at 1400–1500 hours and 42°C at 1500–1600 hours in a climatic chamber. Feed intake (P < 0.01), bodyweight (P < 0.05) and body condition score (P < 0.01) reduced significantly in GII as compared with GI ewes while water intake increased significantly (P < 0.01). All physiological responses also showed significant variation between the groups for treatment. In addition, all endocrine parameters showed highly significant (P < 0.01) variation for the treatment. Plasma cortisol increased significantly (P < 0.01) while T3 (P < 0.01) and T4 (P < 0.01) decreased significantly in GII as compared with GI ewes. Further, plasma oestradiol decreased significantly (P < 0.01) while plasma progesterone increased significantly (P < 0.01) in GII as compared with GI. Among the biochemical parameters, hemoglobin, packed cell volume, plasma glucose, total cholesterol, urea and blood urea nitrogen differed significantly between the groups. In addition, oestrus duration also significantly (P < 0.05) reduced in GII as compared with GI. Based on the results obtained from the study it can be concluded that simulated heat stress influenced the adaptive behaviour of sheep in terms of changes in physiological, blood biochemical and endocrine responses. Ultimately, their growth and reproductive performance are compromised during the process of adaptation to the simulated heat stress.

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The study was designed to identify the most appropriate roughage to concentrate ratio for Malpura ewes under semi-arid tropical environments. The study was conducted for a period of 35 days and included 30 (2 years old) non-pregnant Malpura ewes weighing between 30 and 35 kg. Estrus synchronization was carried out in all the animals using indigenously developed intravaginal sponges impregnated with progesterone. The ewes were randomly divided into three groups (n = 10/group) namely R50 (n = 10; roughage to concentrate, 50:50), R60 (n = 10; roughage to concentrate, 60:40), and R70 (n = 10; roughage to concentrate, 70:30). Individual feed and water intake was recorded on a daily basis throughout the course of the study. Growth variables, physiological responses, blood metabolites, and endocrine responses were estimated at weekly intervals. Results of the study indicated that nutritional treatment significantly influenced growth variables including body weight (p < 0.01), BCS (p < 0.01), feed intake (p < 0.05), and water intake (p < 0.01) among the different treatment groups. The highest growth variables were recorded in R50 whereas the lowest were in R70. Both respiration rate (p < 0.01) and plasma estradiol levels (p < 0.05) also showed a similar trend as that of the growth variables. However, growth hormone (p < 0.01), T3 (p < 0.01), Hb (p < 0.01), glucose (p < 0.05), and estrus duration (p < 0.05) demonstrated a reverse trend with highest values recorded in R70 and lowest in R50. However, the nutritional treatment did not influence pulse rate, rectal temperature, T4, progesterone, PCV, total cholesterol, total protein, albumin, estrus%, and estrus cycle length. Since the additional concentrate supplementation in R50 and R60 did not improve the production variables, it can be concluded that providing 70 % roughage and 30 % concentrate could be a more appropriate and economically feasible ration composition for Malpura ewes reared in semi-arid tropical environments.