Effect of multiple environmental stressors on the adaptive capability of Malpura rams based on physiological responses in a semi-arid tropical environment

Abstract

A 45-day study was conducted where the primary objective was to evaluate the effect of simultaneously imposed multiple stressors (thermal, nutritional, and walking) on the adaptive capability of Malpura rams based on changes in ingestive behavior, physiological, blood biochemical, and endocrine responses. Twenty adult Malpura rams (average body weight 44.9 kg) were used in the study. The rams were divided into 2 groups, CON (n ¼ 10; control) and multiple stressors (MS; n ¼ 10; multiple stressors). All of the rams were stall fed with a diet consisting of 70% roughage and 30% concentrate. The CON rams were maintained in a shed under ambient conditions with ad libitum feeding without walking, whereas MS rams were subjected to multiple stressors (thermal, nutritional, and walking). The feed intake (P < 0.01) was lower and water intake (P < 0.01) was higher in MS compared to CON rams. Among the physiological measurements, respiration rate afternoon (P < 0.01), pulse rate morning (P < 0.01), rectal temperature afternoon (P < 0.01), skin temperature afternoon (P < 0.05), and both morning and afternoon scrotum temperature (P < 0.01) increased significantly in MS rams. Both hemoglobin (P < 0.05), packed cell volume (P < 0.01), increased and plasma glucose (P < 0.01) reduced significantly (P < 0.01) in MS as compared to CON rams. Among the endocrine parameters, the plasma cortisol increased and plasma thyroxin reduced significantly (P < 0.05) in MS rams. The study indicates that Malpura rams have the capability to adjust their physio-biochemical and endocrine responses to cope with multiple stressors in a hot semi-arid environment. Furthermore, the study also indicated that respiration rate, rectal temperature, scrotal temperature, hemoglobin, packed cell volume, and cortisol may act as ideal biological markers for quantifying the impact of multiple stressors in Malpura rams.