<abstract xmlns="http://www.w3.org/1999/xhtml"><p> This study aimed to evaluate glucose-induced insulin response in cows exposed to different temperature-humidity index. Twenty early lactating Holstein-Friesian cows were divided into 2 equal groups based on season, as summer (SU) and spring (SP). SP cows were not exposed to heat stress, while SU cows were exposed to moderate or severe heat stress. Milk production was recorded daily. Starting from day 30 of lactation, intravenous glucose tolerance test (IVGTT) was carried out three times at 30-day intervals. Blood samples were taken before (basal) and after glucose infusion, and glucose and insulin were measured at each sample point. The homeostatic model assessment (HOMA) index was calculated. Milk yield from days 30 to 40 and 64 to 90 of lactation were higher in SP cows than in SU cows. Basal glucose did not differ on days 30 and 60 of lactation, while basal insulin and HOMA were lower in SU compared to SP cows. On day 90 of lactation, SU cows had higher basal glucose, whereas basal insulin and HOMA did not differ. IVGTT results revealed that glucose tolerance was affected by heat stress such that SU cows had higher glucose clearance. Insulin responses to IVGTT did not differ on days 30 and 60 of lactation. Heat stress had a marked effect on insulin secretion on day 90 of lactation, illustrated by higher increments, peak concentrations and area under the curve for insulin in SU cows. Overall, season differences in glucose tolerance depend not only on heat stress and milk production but also on the stage of lactation.</p></abstract>

This study aimed to evaluate glucose-induced insulin response in cows exposed to different temperature-humidity index. Twenty early lactating Holstein-Friesian cows were divided into 2 equal groups based on season, as summer (SU) and spring (SP). SP cows were not exposed to heat stress, while SU cows were exposed to moderate or severe heat stress. Milk production was recorded daily. Starting from day 30 of lactation, intravenous glucose tolerance test (IVGTT) was carried out three times at 30-day intervals. Blood samples were taken before (basal) and after glucose infusion, and glucose and insulin were measured at each sample point. The homeostatic model assessment (HOMA) index was calculated. Milk yield from days 30 to 40 and 64 to 90 of lactation were higher in SP cows than in SU cows. Basal glucose did not differ on days 30 and 60 of lactation, while basal insulin and HOMA were lower in SU compared to SP cows. On day 90 of lactation, SU cows had higher basal glucose, whereas basal insulin and HOMA did not differ. IVGTT results revealed that glucose tolerance was affected by heat stress such that SU cows had higher glucose clearance. Insulin responses to IVGTT did not differ on days 30 and 60 of lactation. Heat stress had a marked effect on insulin secretion on day 90 of lactation, illustrated by higher increments, peak concentrations and area under the curve for insulin in SU cows. Overall, season differences in glucose tolerance depend not only on heat stress and milk production but also on the stage of lactation.

Field Trial on Glucose-Induced Insulin Response in High-Yielding Dairy Cows under Different Environmental Temperatures

Acta Veterinaria

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

This study aimed to evaluate glucose-induced insulin response in cows exposed to different temperature-humidity index. Twenty early lactating Holstein-Friesian...

Field Trial on Glucose-Induced Insulin Response in High-Yielding Dairy Cows under Different Environmental Temperatures

Published Online: Sep 23, 2017

Page range: 366 - 382

Received: Sep 20, 2016

Accepted: Mar 06, 2017

DOI: https://doi.org/10.1515/acve-2017-0030

Keywords
dairy cows, heat stress, intravenous glucose tolerance test, HOMA

© by Danijela Kirovski

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Field Trial on Glucose-Induced Insulin Response in High-Yielding Dairy Cows under Different Environmental Temperatures

Published Online: Sep 23, 2017

Page range: 366 - 382

Received: Sep 20, 2016

Accepted: Mar 06, 2017

DOI: https://doi.org/10.1515/acve-2017-0030

Keywordsdairy cows, heat stress, intravenous glucose tolerance test, HOMA

© by Danijela Kirovski

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Keywords
dairy cows, heat stress, intravenous glucose tolerance test, HOMA