Temperature-humidity index is associated with heat stress and milk yield of dairy cows

Nakov, Dimitar and Trajchev, Metodija and Andonov, Sreten (2022) Temperature-humidity index is associated with heat stress and milk yield of dairy cows. Book of abstracts of The IV International Symposium for Agriculture and Food. ISSN 13978-9989-76-5

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Abstract

Exposure of dairy cows to a thermal environment is a major risk factor for decreased milk production, especially in high-yielding cows. Temperature humidity index (THI) is an important indicator of heat stress loading. Heat stress in dairy cows occurs when THI is higher than 72. The objective of this study was to evaluate the effect of THI on the daily production of dairy cows. The survey was conducted in the summer season from 15th of June to 15th of September. There were include two small family dairy farms with installed cooling systems for microclimate controlling. Totally 18 dairy cows from Holstein black-white breed were subjected to the study (6 cows in farm A and 12 cows in farm B). During the trial period daily average air temperature and relative humidity, as well THI were calculated from the hourly data gained from the automated temperature and humidity data loggers on-farm. The daily milk yield per cow was estimate as sum of milk yield gaining during the morning and evening milking. Test-days data were analyzed using General linear model, univariate procedure to determine the threshold of THI and heat stress and their influence on decline of milk production. The value of THI was ranged from 61.82 to 89.34, which indicates the existence of the moderate intensity of heat stress. THI was in a significant negative correlation with the milk yield and there was existing high positive correlation between THI and heat stress. The present results revealed that the combined effects of air temperature and humidity associated with the level of thermal stress make the considerable loss in the milk production of the dairy cows.
Keywords: lactation, dairy barn, thermal comfort

Item Type:	Article
Subjects:	Agricultural Sciences > Animal and dairy science Agricultural Sciences > Veterinary science
Divisions:	Faculty of Agriculture
Depositing User:	Dimitar Nakov
Date Deposited:	22 Nov 2023 13:19
Last Modified:	22 Nov 2023 13:19
URI:	https://eprints.ugd.edu.mk/id/eprint/32620

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