The deleterious effects of heat stress on animal health are being increasingly recognized. This study aimed to determine hair cortisol (HC) and serotonin levels in lactating Holstein cows under heat stress conditions with different coat and hair-cut color. Forty-five multiparous lactating Holstein cows (days in milk = 130 ± 47, body weight = 753 ± 85 kg) were divided to two main groups of over 80% black coat color (BC) and over 85% white coat color (WC) visually observed based on registry certificates and subdividing to black hair sample (BH) and white hair samples (WH) in 2 × 2 factorial arrangements. Hair samples were taken from the forehead of the individuals. Higher HC levels were observed in BC than WC cows (P < 0.05). No differences were found in HC levels between BH and WH groups (P > 0.05). Serotonin levels showed no difference between BC and WC (P > 0.05). Interaction between coat color and hair color was not significant (P > 0.05). The cortisol levels in hair are not affected by pigmentation. However, pigmentation within the coat alters cortisol levels. In conclusion, white coat color retains less cortisol than the black coat. Therefore, white coats are preferable for dairy cows under heat stress conditions.
Dear Assemu Tesfa,
Thaks for your comment. More research on gene alteration can provide selective color of Holstein breeds or others. This color manipulate can easily progress through AI and selective color breeding along with other traits in order to maitain the production quality (meat and milk) in such a harsh (cold or hot-humid) environment.
Regards,
Jalil.
The result of this publication is very important because it brings something new and logical. I hope it can be used practically in farms and bring new knowledge into the area.
It is a good point that mentioned here , but in my opinion genetically the cows ,dogs and horses are not the same, related to HF cows we could mention that they are more sensitive to heat stress then other breeds of cows, in tropical and sub tropical condition how to keep this bred? if we try to keep cold the cows, need more cost due electricity, in these days the trade of HF to sub tropical country e.g. Afghanistan, the heat stress is higher.