Influence of temperature-humidity index level on ovarian activity and conception rate in Egyptain baladi cows under climatic conditions of Aswan governorate

الملخص EN

The present investigation aimed to study the effects of temperature-humidity index (THI) level, on the ovarian activity and conception rate of Egyptian Baladi cows.

A total number of 40 Baladi cows was used in this study.

The cows were divided into three groups according to time of calving.

The first group (15 cows) calved during (December, January and February) where THI (68.1- 70.5) was considered as (non-heat stress), the second group calved during (November, March and April) THI (74.5- 76.9) (mild-heat stress=10 cows) and the third group calved during (May to October) THI (80.1- 83.9) (moderate-heat stress= 15 cows).

The results demonstrated that the percentage of cows that resumed ovarian activity post-partum were significantly (P<0.05) higher 73.3% in the first group compared to 50 and 33.3% in the second and third groups, respectively.

Incidence, of quiet ovulation was higher (20%) in the second and third groups compared to first group (18.2%).

The percentage of anestrous cases was significantly (P <0.05) higher (50, 66.7%) in the second and third group compared with the first group (36.4%).

Conception rate was significantly (P<0.05) higher (77.8%) in the first group compared to third group (50%).

The intensity of estrus symptoms was significantly (P<0.05) higher in the first group compared to the second and third groups.

In conclusion, the present results illustrated the detrimental effect of increased temperature-humidity index level (THI) on ovarian activity and conception rate of Egyptian Baladi cows.

This study recommends the stockholders of cows in Aswan governorate to arrange the cows calvings during the cold months or use some procedures such as sprinkling by water and fan in order to reduce the hurtful effects of higher THI level on fertility in Egyptian Baladi cows.