Effects of heat stress on the endometrial epidermal growth factor profile and fertility in dairy cows

Abstract

The endometrial epidermal growth factor profile is an indicator of uterine function and fertility in cattle. The present study aimed to investigate the effects of heat stress on the endometrial EGF profile and fertility in lactating Holstein cows. The endometrial EGF profiles of 365 cows in the Hokkaido and Kyushu regions were examined between June and September (heat stress period, n = 211) and between October and January (control period, n = 154). EGF profiles were investigated using uterine endometrial tissues obtained by biopsy 3 days after estrus (Day 3). The proportion of cows with an altered EGF profile was higher between June and September than between October and January (41.2 vs. 16.2%, p < 0.05). The effects of rectal temperature on Days 0 and 3 on the endometrial EGF profile were also assessed in cows (n = 79) between June and September in the Kyushu region. A single embryo was transferred to cow on Day 7 to evaluate fertility (n = 67).Regardless of the rectal temperature on Day 3, the proportion of cows with an altered EGF profile was higher (64.1 vs. 30.0%, p < 0.05) and the pregnancy rate after embryo transfer (ET) was lower (26.7 vs. 51.4%, p < 0.05) in cows with a rectal temperature ≥ 39.5C on Day 0 than in cows with a rectal temperature < 39.5C on Day 0. The present results indicate that alterations in the endometrial EGF profile induced by an elevated body temperature on Day 0 contributed to reductions in fertility in lactating dairy cows during the heat stress period.

Equine chorionic gonadotropin treatment and timed artificial insemination for dairy cow production under heat stress

“…Epidermal growth factors (EGF) in the endometrium are critical for reproduction in mammals [ 37 , 38 ], including dairy cows [ 39 ]. Moreover, high parity [ 40 ] and heat stress [ 41 ] increase the risk of EGF abnormalities in dairy cows. Another theory is that lipopolysaccharide (LPS), an endotoxin produced by gram-negative bacteria, reduces gonad receptivity to hormonal stimulation [ 42 ].…”

Preventive Supplementation of Vitamin E and Selenium as a Factor in Improving the Success Rate of Embryo Transfer in Cattle

“…Due to the stress from overheating of an organism, the concentration of cortisol also increases. Cortisol is a stress hormone from the adrenal gland, which inhibits the implantation of the embryo into the uterine wall and causes early loss of embryos [10,11]. An ovulated oocyte from an inferior follicle shows signs of inferior quality; it has lower fertility; therefore, several inseminations are required for successful fertilization.…”

“…Many embryos fail soon after fertilization, when they have only two or four cells. During the fi rst few days after fertilization, the embryos are much more sensitive to heat stress than at a later stage, when their own ability to adapt has already developed [10,11].…”

In Vitro Effects of Short-Term and Long-Term Heat Exposures on the Immune Response and Prostaglandin Biosynthesis in Bovine Endometrial Cells

“…Indeed, a recent study found that the group of cows that experienced HS (THI of ≥ 73) 3 weeks before insemination had more unfertilized oocytes than the control (21% vs. 4%, respectively), a lower conception rate, and reduced embryo development during the first 16 gestational days [ 17 ]. Moreover, HS can affect endometrial functions, e.g., prostaglandin and protein secretion [ 18 , 19 ].…”