Effect of different types of shelter on microenvironment, physiological response and growth performance of lambs under semi-arid tropical environment during summer

Heat stress is a major predisposing factor for impaired growth performance of growing lambs during summer in semi-arid tropics. Therefore, the present study was conducted to ameliorate heat stress in growing lambs through shelter management. Thirty three Malpura lambs of 3-5 months age (average body weight 19.5 kg) were divided equally and randomly into three groups, viz. GI (control, lambs kept in conventional asbestos roof shed), GII (lambs kept in Yagga type shed) and GIII (lambs kept in open area under tree-shade) to determine the effect of different types of shelter on microenvironment, physiological response and growth performance of lambs under hot semi-arid tropical environment during summer. In all three type of system lambs were provided with sufficient space to move and play. The side walls of asbestos roof were made up of wire netted fencing where as in Yagga type shed; the side walls are double walled. The empty space between the two walls, were filled with sand. The sand was kept in moist condition by continuous water drips which provide extra evaporative cooling. The Yagga type shed was basically constructed with bamboo. Tree-shade was made under the natural shades of large trees. The shaded area was protected by wire fence. The experiment was conducted for two months during extreme summer (May-June, 2013). During the experimental period the temperature-humidity index remained 33.73±1.23, 32.42±1.26 and 37.60±0.38, respectively in the shed of GI, GII and GIII at 1400h. Whereas, maximum temperature remained 45.48±0.51, 41.42±0.47 and 43.46±0.44 at 1400 h during experimental period in the shed of GI, GII and GIII, respectively. The lambs were provided with adlibitum green fodder, dry roughage, 200 g concentrate and adlibitum drinking water. The respiration rate at morning and afternoon, pulse rate at morning and afternoon and rectal temperature at afternoon was significantly (p<0.05) lower in lambs of GII as compared to other groups. Body weight did not differ significantly among the groups but average daily gain (g/day) was higher in GII (112.57±21.74) as compared to GI (94.99±21.74) and GIII (94.45±20.73). It can be conclude from this study that amongst the three housing types, Yagya-type shed (GII) provided maximum comfort with lower THI, temperature, physiological responses of lambs and higher average daily gain during extreme summer in semi-arid tropical environment.