T3 and Ovines

T3 and Ovines

If you want a T3 test, pretend to be a sheep? :-) :-) :-)

Perhaps a relevant bit to more of us is this: Exposure to cold temperature increased plasma T3 concentration... How much does ambient temperature affect our T3 levels? Could our centrally heated houses keep our T3 levels low?

J Anim Physiol Anim Nutr (Berl). 2015 Jun;99(3):483-91. doi: 10.1111/jpn.12252. Epub 2014 Oct 1.

Low ambient temperature elevates plasma triiodothyronine concentrations while reducing digesta mean retention time and methane yield in sheep.

Barnett MC1, McFarlane JR, Hegarty RS.

Author information

Abstract

Ruminant methane yield (MY) is positively correlated with mean retention time (MRT) of digesta. The hormone triiodothyronine (T3 ), which is negatively correlated with ambient temperature, is known to influence MRT. It was hypothesised that exposing sheep to low ambient temperatures would increase plasma T3 concentration and decrease MRT of digesta within the rumen of sheep, resulting in a reduction of MY. To test this hypothesis, six Merino sheep were exposed to two different ambient temperatures (cold treatment, 9 ± 1 °C; warm control 26 ± 1 °C). The effects on MY, digesta MRT, plasma T3 concentration, CO2 production, DM intake, DM digestibility, change in body weight (BW), rumen volatile fatty acid (VFA) concentrations, estimated microbial protein output, protozoa abundance, wool growth, water intake, urine output and rectal temperature were studied. Cold treatment resulted in a reduction in MY (p < 0.01); digesta MRT in rumen (p < 0.01), hindgut (p = 0.01) and total digestive tract (p < 0.01); protozoa abundance (p < 0.05); and water intake (p < 0.001). Exposure to cold temperature increased plasma T3 concentration (p < 0.05), CO2 production (p = 0.01), total VFA concentrations (p = 0.03) and estimated microbial output from the rumen (p = 0.03). The rate of wool growth increased (p < 0.01) due to cold treatment, but DM intake, DM digestibility and BW change were not affected. The results suggest that exposure of sheep to cold ambient temperatures reduces digesta retention time in the gastrointestinal tract, leading to a reduction in enteric methane yield. Further research is warranted to determine whether T3 could be used as an indirect selection tool for genetic selection of low enteric methane-producing ruminants.

Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

KEYWORDS:

T3; hormonal regulation; kinetics; rumen efficiency

PMID:

25271888

[PubMed - in process]

ncbi.nlm.nih.gov/pubmed/252...

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  • ....and as Martyn Hooper informed us at the Thyroid UK conference last year - sheep do get depressed and are unable to follow the flock ! Back in the shed with the Shepherd Martyn was introduced to 5 gallon containers of pink stuff - Could it be B12 ? Yes it was ! Apparently over 80% of B12 produced in Europe goes into animals.

    Now I am wondering after Rod's post - Could it be T3 ?

  • I used to go off on cycle camping trips, and these were quite "trippy" when contemplating the capabilities of my body. One aspect was how the length of time to feel truly comfortable in cool and damp conditions shortened from three days to the first day of the trip. I'm pretty sure reserves of T3 were released to cope with the challenge. More recently a major stress sent me hyper before hypo and I guess there's a protective mechanism (Wilson's Temperature Syndrome) messing up my temperature regulation.

  • Splendid. Another reason to keep Wiltshire Horns (they moult and therefore must be a bit chillier than woolly sheep). And the heating goes off now! Anything's worth a try.

  • Added a picture just for ewe. :-)

  • Thankyou! That's a good mum. Obviously her T3 is up.

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