Differences in glucose response to insulin stimulation and fasting between Angora goats of two different phenotypes

Cronje, P. B.

doi:10.1016/0921-4488(95)00627-w

Cited by 4 publications

(1 citation statement)

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“…Our Angora goats also showed an increased blood glucose concentration immediately after shearing (Figure 7, lower panel). We caution, though, that blood glucose concentration may not be a reliable index of energy status of Angora goats, since Angora goats have an abnormal glucose homeostasis, brought about by selection for high levels of mohair production (Cronje, 1995). Nevertheless, since air temperature often fell below the lower critical temperature of 208C reported for shorn Angora goats in dry conditions (Fourie, 1984), we believe our goats would have had increased metabolic rates, and so produced more metabolic water.…”

Section: Discussionmentioning

confidence: 79%

Shearing at the end of summer affects body temperature of free-living Angora goats (Capra aegagrus) more than does shearing at the end of winter

Hetem

Witt

Fick

et al. 2009

Animal

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Angora goats are known to be vulnerable to cold stress, especially after shearing, but their thermoregulatory responses to shearing have not been measured. We recorded activity, and abdominal and subcutaneous temperatures, for 10 days pre-shearing and post-shearing, in 10 Angora goats inhabiting the succulent thicket of the Eastern Cape, South Africa, in both March (late summer) and September (late winter). Within each season, environmental conditions were similar pre-shearing and post-shearing, but September was an average 58C colder than March. Shearing resulted in a decreased mean ( P , 0.0001), minimum ( P , 0.0001) and maximum daily abdominal temperature ( P , 0.0001). Paradoxically, the decrease in daily mean ( P 5 0.03) and maximum ( P 5 0.01) abdominal temperatures, from pre-shearing to post-shearing, was greater in March than in September. Daily amplitude of body temperature rhythm ( P , 0.0001) and the maximum rate of abdominal temperature rise ( P , 0.0001) increased from preshearing to post-shearing, resulting in an earlier diurnal peak in abdominal temperature ( P 5 0.001) post-shearing. These changes in amplitude, rate of abdominal temperature rise and time of diurnal peak in abdominal temperature suggest that the goats' thermoregulatory system was more labile after shearing. Mean daily subcutaneous temperatures also decreased post-shearing ( P , 0.0001), despite our index goat selecting more stable microclimates after shearing in March ( P 5 0.03). Following shearing, there was an increased difference between abdominal and subcutaneous temperatures ( P , 0.0001) at night, suggesting that the goats used peripheral vasoconstriction to limit heat loss. In addition to these temperature changes, mean daily activity increased nearly two-fold after March shearing, but not September shearing. This increased activity after March shearing was likely the result of an increased foraging time, food intake and metabolic rate, as suggested by the increased water influx ( P 5 0.0008). Thus, Angora goats entered a heat conservation mode after shearing in both March and September. That the transition from the fleeced to the shorn state had greater thermoregulatory consequences in March than in September may provide a mechanistic explanation for Angora goats' vulnerability to cold in summer.

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Section: Discussionmentioning

confidence: 79%