Effects of mild heat exposure and suppression of prolactin secretion on gastro-intestinal tract function and temperature regulation in sheep
1986
Faichney, G.J. | Barry, T.N. (Commonwealth Scientific and Industrial Research Organization, Blacktown (Australia). Div. of Animal Production)
Exposure to 30 degrees C at 30 percent R.H. reduced the digesta-free tissue weight of all tract segments distal to the omasum. Increases in the amounts of digesta in the stomach compartments were largely due to increases in water content, although the solids content of the abomasum and omasum also increased. The mild heat caused an increase in water intake, increased the mean retention time (MRT) of 15Cr-EDTA in the reticulo-rumen, and tended to increase the MRT of 15Cr-EDTA, 103Ru-phenanthroline and lignin in the omasum and abomasum; MRT in the whole tract was unaffected because of a compensating decrease in digesta MRT in the distal large intestine. Suppression of prolactin secretion impaired maintenance of body temperature under the mild heat, reduced the effects of mild heat on water intake and usage, decreased omasal MRT and increased abomasal MRT. Some of the effects of prolactin on the tract may be mediated via somatostatin.
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