A study was conducted to examine the effects of solar Radiation exposure (RAD) on thermoregulatory and growth performance of goat kids. Five indigenous black Bedwin goat kids were exposed to daytime RAD (Days 8-28) after an initial 7 day Shading (SHD) period, while another 5 kids (n=5) were exposed to SHD regimen throughout the entire 28-day study period as a control group. Daily measurements (3 times, at 0600; morning, 1200; noon and 1900; night) included Respiratory Rate (RR), Heart Rate (HR) and Temperatures of skin (Tskin), hair coat (Tcoat) and rectum (Trec). Growth parameters including Body Weight (BW), Average Daily Weight Gain (ADWG), Average Daily Feed Intake (ADFI) and Feeding Efficiency (FE) were measured on days 1, 7 and 28. Response analyses within the total study duration were divided into 3 stages, stage 1 (first 7 days), stage 2 (next 10 days) and stage 3 (the last 11 days). Noon RR rose transiently from SHD levels for 2 days upon RAD onset and then returned back to SHD levels onwards. Values of HR increased in stages 2 and 3 compared to 1, without a treatment effect. Measurements of Tskin and Tcoat at noon revealed an advantage of RAD over SHD group starting with RAD regimen. However, morning Tskin were lower in RAD group as compared to SHD during stage 3 compared to the previous stages. Unlike RR, Trec did not experience any significant rise at any time of the day. Furthermore, no significant alterations were noticed in any growth parameter measured. The indigenous black Bedwin goats of Jordan seem to be highly tolerant to heat stress as evidenced by the lack of significant displacements in thermoregulatory and growth parameters after chronic exposure to solar radiation.
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Hosam J. Al-Tamimi, 2005. Effects of Solar Radiation on Thermophysiological and Growth Parameters of Indigenous Black Bedwin Goat Kids in Southern Jordan. Journal of Biological Sciences, 5: 724-728.
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