PERFORMANCE OF CROSSBRED CALVES UNDER MODIFIED HOUSING SYSTEM DURING HOT-HUMID SEASON.

The present study was conducted on crossbred (Vrindavani) cattle calves to evaluate the effect of modified housing using different roofing materials on growth and physiological performance of calves during the rainy season. A total of twenty four calves (9-11 months old) were randomly selected and allocated in 4 groups viz. control (C): corrugated cemented sheet (CCS) as roofing material, T1: the CCS roof was painted black inside and white outside, T2: polycarbonate plastic sheet as roof and T3: polycarbonate roof with adjustable height. The overall average temperature was significantly (P<0.05) lower in T1 (26.89±0.04), followed by T3 (28.18±0.11), T2 (29.74±0.19) and C (30.55±0.06). Similarly temperature of the inner surface of roof was significantly (P<0.05) lower in T1 followed by T3 and higher in C during every fortnight. Overall average relative humidity (per cent) was significantly (P<0.05) lower in T3 (77.08±0.31) as compared to T1 (80.50±0.26), T2 (82.10±0.76) and C (82.92±0.12). Overall average THI was significantly (P<0.05) lower in T3 (76.56 ±0.23) followed by T1 (76.96 ± 0.07), T2 (78.35 ± 0.23) and C (79.30 ± 0.18). Total body weight gain (kg) was higher in T1 (32.67±0.76), followed by T3 (31.67±0.84), T2 (31.00±1.24) and C (30.83±0.48), however the difference was non-significant. The overall FCR was significantly lower (P<0.05) in T1 (9.94±0.24), T3 (10.01±0.14) followed by T2 (10.89±0.16) as compared control (11.76±0.18). The overall average rectal temperature and average respiration rate was significantly higher (p<0.05) in C (39.32±0.05 ºC, 26.07±0.29/min), followed by T2 (39.18±0.04 ºC, 24.17±0.37/min) and lower in T1 (38.98±0.03 ºC, 22.56±0.26/min) and T3 (39.06±0.03 ºC, 22.43±0.25/min). It may be inferred that the micro-environment was more conducive in T1 and T3 than control; hence the reflective paints on roof and adjusted higher height of polycarbonate roof may be the desirable choice for animal housing in view of mitigating heat stress during the hot-humid climate. [ABSTRACT FROM AUTHOR]