1Department
of Bioengineering, Sichuan Water Conservancy Vocational College,
Chengdu 611231, China
2Institute of Animal Science,Chengdu
Agricultural College, Chengdu 611130, China
*Corresponding author:
chenxiaochun163@163.com
Abstract
The current study was planned to evaluate the effects of
heat stress (HS) on mammary blood flow and the profile of circulating amino
acids (AA) in blood and milk of lactating Holstein dairy cows. For this purpose,
twenty dairy cows with similar body conditions, parity, and milk production were
divided into two treatments of 10 animals each. The first treatment group was
exposed to HS and reared in summer season, and second treatment group were
reared in thermoneutral environment (TN) during spring season. Results showed
that HS resulted in high level of total AA (TAA), glycine, serine (Ser), alanine
(P<0.05) predominantly while decrease concentrations of methionine (Met) and
tryptophan (Trp) predominantly (P<0.05) in external pudic artery and mammary
vein of experimental cows. Methionine, arginine (Arg), Trp and threonine (Thr)
(P<0.05) supply to the mammary gland by pudic artery and lower amount of Met and
Trp in mammary vain output (P<0.05) was observed in HS cows. Similarly, the
uptake of most AA in the udder was decreased due to HS (P<0.05) and resulted in
a lower (P<0.05) amount of TAA, glutamine, phenylalanine, Met, lysine, leucine,
tyrosine, isoleucine, Ser, Thr, valine, and histidine in milk. A highly
significant decrease (P<0.01) in amount of Arg and Trp in milk was observed in
HS cows. Therefore, it is concluded that during HS blood AA use in dairy animals
is shifted away from milk protein synthesis by lower mammary blood flow and AA
uptake by mammary gland.
To Cite This Article:
Yue S, Qian J, Du J, Liu X, Xu H, Liu H, Zhang J, Chen X. 2023.
Heat stress negatively influence mammary blood flow, mammary uptake of amino
acids and milk amino acids profile of lactating holstein dairy cows.
Pak Vet J. http://dx.doi.org/10.29261/pakvetj/2023.002