Physiological Responses and Lactation to Cutaneous Evaporative Heat Loss in XXXX , @entity291 , and Their Crossbreds.

@entity5584 @entity291 @entity7040
UNASSIGNED: Cutaneous evaporative heat loss in @entity7040 and @entity291 has been well documented. Nonetheless, how crossbreds with different fractional genetic proportions respond to such circumstances is of interest. A study to examine the physiological responses to cutaneous evaporative heat loss, also lactation period and milk yield, were conducted in Sahiwal ( @entity7040 , n = 10, 444  64.8 kg, 9  2.9 years), Holstein Friesian ( @entity291 , HF100% (n = 10, 488  97.9 kg, 6  2.8 years)) and the following crossbreds: HF50% (n = 10, 355  40.7 kg, 2  0 years) and HF87.5% (n = 10, 489  76.8 kg, 7  1.8 years). They were allocated so as to determine the physiological responses of sweating rate (SR), respiration rate (RR), @entity5584 ( @entity5584 ), and skin temperature (ST) with and without hair from 06:00 h am to 15:00 h pm. And milk yield during 180 days were collected at days from 30 to 180. The ambient temperature-humidity-index (THI) increased from less than 80 in the early morning to more than 90 in the late afternoon. The interaction of THI and breed were highly affected on SR, RR, @entity5584 , and ST (p<0.01). The SR was highest in Sahiwal (595 g/m(2)/h) compared to HF100% (227 g/m(2)/h), and their crossbreds both HF50% (335 g/m(2)/h) and HF87.5% (299 g/m(2)/h). On the other hand, RR was higher in HF87.5% (54 bpm) and both HF100% (48 bpm) and HF50% (42 bpm) than Sahiwal (25 bpm) (p<0.01). The @entity5584 showed no significant differences as a result of breed (p>0.05) but did change over time. The ST with and without hair were similar, and was higher in HF100% (37.4  C; 38.0  C) and their crossbred HF50% (35.5  C; 35.5  C) and HF87.5% (37.1  C; 37.9  C) than Sahiwal (34.8  C; 34.8  C) (p<0.01). Moreover, the early lactation were higher at HF100% (25 kg) and 87.5% (25 kg) than HF50% (23 kg) which were higher than Sahiwal (18 kg) while the peak period of lactation was higher at HF100% (35 kg) than crossbreds both HF87.5% and HF50% (32 kg) which was higher than Sahiwal (26 kg) (p<0.05). In conclusion, sweating and respiration were the main vehicle for dissipating excess body heat for Sahiwal, HF and crossbreds, respectively. The THI at 76 to 80 were the critical points where the physiological responses to elevated temperature displayed change.
