Study of influence of heat stress on some physiological and productive traits in Holstein-Friesian dairy cows
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Kuupäev
2021
Kättesaadav alates
Autorid
Penev, T.
Dimov, D.
Marinov, I.
Angelova, T.
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
The aim of the research was to study the effect of heat stress (HS) on some physiological
and productive traits in Holstein-Friesian dairy cows. The study included 22 cows on different
parities. In the building where the cows were housed, the temperature-humidity index (THI) was
reported at 10:00 and 15:00 h, at the same time the rectal temperature (RT) and respiratory rate
(RR) were reported for each of the examined cows. The daily rumen activity was taken from the
SCR system by Allflex. The average THI values in May were 71, in June - 75, in July - 74, and
in August - 77, from which it follows that in the summer months the cows were in conditions of
mild to moderate heat stress throughout the day. The average daily milk yield of the cows increased
from May to June and reached 41.44 kg day-1
, then decreased in July and August to 37.2 and
32.48 kg day-1
, respectively. With an increase in the THI values, an increase in the RR and RT
was registered, as in THI above 79 the RR was 56.54 per min, and the RT was 39.33 °C. With
increasing the THI values, the rumination of the cows decreased from 563 per day at THI < 72 to
542.5 at THI > 79. In cows with high daily milk yield, a higher RT was registered, and in cows with
more than 50 kg per day, the RT was 39.09 °С. A more intense rumination was found in cows
with higher daily milk yield. In cows with an average daily milk yield of 33.26 kg, an average of
450 ruminations per day were reported, and in those with an average milk yield of up to 42.89 kg
- 650 ruminations per day. From the research conducted it was found that the studied
physiological traits - rectal temperature, respiration rate and rumination are influenced by HS and
the intensity of this effect depend on the daily milk yield of cows and THI levels.
Kirjeldus
Received: October 6th, 2020 ; Accepted: February 1st, 2021 ; Published: March 18th, 2021 ; Correspondence: tonchopenev@abv.bg
Märksõnad
dairy cows, heat stress, rectal temperature, respiratory rate, temperature-humidity index, articles