Physiological, haematological and electroencephalographic responses to heat stress in Katjang and Boer goats

The objective of this study was to compare the effect of repeated heat stress on serum levels of cortisol (CORT), acute phase proteins (APP) and heat shock protein (HSP) 70, and haematological indicators, and electroencephalographic (EEG) response in the native Katjang and exotic Boer goats. In the first experiment, we evaluated the response of six female Katjang (15.7 kg + 0.68) and of six female Boer (16.8 kg + 1.16) goats (at a common age of 5 to 6 months old) to 38±1℃ for 8 hours, and the procedure was repeated at three different weeks (weeks 1, 2 and 3). Measurements of rectal temperatures and EEG activity and collection of blood samples were conducted before heat exposure (0 h), immediately after the heat exposure (8 h), and 8 h after completion of heat exposure (16 h) (recovery period). The current results revealed that the Boer animals had significantly higher rectal temperatures (RT), haemoglobin (Hb) and packed cell volume (PCV) counts than their Katjang counterparts. There were significant breed x stage of heat treatment (SHT) x week of heat treatment (WHT) interactions for neutrophil to lymphocyte ratios (NLR). In general, the Katjang animals had elevated NLR compared to those of Boer. The Boer goats had reduced capacity to express serum HSP70 compared to their Katjang counterparts following the heat challenge at week 3. Boer goats demonstrated higher delta waves than the Katjang group, which suggested the former were more stressed following the heat exposure. Breed had a negligible effect on CORT, APP, WBC counts and backfat thickness. The results of this research indicated that the Katjang breed, in terms of RT, HB and PCV counts, and EEG activity, could be more tolerant to heat stress than Boer. The Katjang goats showed higher HSP70 expression than their Boer counterparts, suggesting a better heat stress regulation activity in the former. In the second experiment, we determined the response of six female Katjang (aged 18 months) and six female Boer (aged 9 – 12 months) goats (at a common body weight of 20±2 kg) to 38±1℃ for 8 hours, and the procedure was repeated at three different weeks (weeks 1, 2 and 3). Measurements of rectal temperatures and EEG activity and collection of blood samples were conducted before heat exposure (0 h), immediately after the heat exposure (8 h), and 8 h after completion of heat exposure (16 h) (recovery period). The current result shows significant SHT x breed and WHT x SHT interactions for RT. Katjang goats had a significantly higher RT than Boer goats. In general, Katjang goats had a significantly higher NLR at SHT 0 h and SHT 8 h compared to Boer goats. There were significant SHT x WHT interactions for HSP70. AT WHT 1, SHT had no significant effect on HSP70. Breed had a significant effect on theta waves and the total power of EEG. The Boer animals had significantly higher theta waves than their Katjang counterparts, but the converse was noted for the total power of EEG. As revealed by RT and EEG activity, Katjang goats showed a better resistance to heat stress than Boer counterparts.

Text IPTSM 2023 3 - IR.pdf Download (819kB) Official URL or Download Paper: https://ethesis.upm.edu.my/id/eprint/18688

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