An in-feed OGT was performed at 08.00 h on 3 consecutive occasions under controlled conditions in 8 mixed breed ponies. d-glucose (0.75 g/kg bwt) was dissolved in water and combined with wheat bran and lucerne chaff.
Blood samples were taken before and 90, 120, 180 min and 24 h after d-glucose.
The repeatability of the test was analysed with repeated measures ANOVA.
Insulin and glucose responses to d-glucose were also compared to an equivalent dose of dietary carbohydrate provided with a commercial grain mixture.
The overall insulin responses to the OGTs did not differ between tests.
Individual insulin responses were more variable (P<0.05) than glucose responses.
There was no difference in insulin concentration in post d-glucose samples over time.
Insulin and glucose responses to grain and d-Glucose were not different.
An OGT is reasonably repeatable in ponies.
The currently recommended post-glucose sampling time point of 2 h is acceptable, with sampling at 90 min also likely to produce a consistent result.
The use of an alternative carbohydrate source to d-glucose, such as a commercial grain-based product, may be a viable and more palatable option for the test.
Source: de Laat, M. A. and Sillence, M. N. (2016), The repeatability of an oral glucose test in ponies. Equine Veterinary Journal. doi: 10.1111/evj.12579
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