Heatwave impact on cattle fertility

A farmer in the Somme region discovered through ultrasound that a cow confirmed pregnant two months ago is now not pregnant. This highlights the potential effects of extreme weather on cattle reproduction.

Heat stress and reproductive issues

Damien Meriaux, a reproduction technician at Gènes Diffusion, explained that heatwaves can lower the quality of oocytes, which are the female reproductive cells needed for fertilization. This can lead to problems with conception and early pregnancy loss.

Signs of reproductive distress

Observations on farms show increased instances of abortions after 70 days and delayed returns to heat after 60 days. These signs suggest early embryonic losses before 40 days, which can cause health problems in the reproductive system, such as uterine infections.

Abnormal follicles and heat

Abnormal follicles have been seen on many farms, especially when nighttime temperatures stayed above 30 °C. Since early August, pregnancy checks have shown many cases of ovarian blockage with these abnormal follicles.

Impact of heat on ovulation

In a normal 21-day ovarian cycle, two to three follicular waves occur, with the last wave producing a "De Graff" follicle that leads to ovulation. However, thermal stress can disrupt this process, causing cycle blockage and preventing follicle maturation and ovulation.

Delayed effects on reproduction

The negative effects of heatwaves on reproduction may be felt 60 to 80 days after the heatwave. This means that the heat of August could affect reproduction in October, as inseminations depend on oocytes produced two months or more earlier.

Hormonal treatments for recovery

Hormonal treatments, such as progestogens or GnRH injections, can help restart normal reproductive cycles by encouraging follicle growth and ovulation.

Early embryo loss and complications

Mid-September has seen many early embryo losses in confirmed pregnant cows, leading to complications like metritis, an inflammation of the uterus. These issues can be addressed with natural prostaglandin, which helps eliminate infections.

Monitoring reproductive health

Milking robots equipped with progesterone dosage options, such as those from DeLaval, can help monitor reproductive status. High progesterone levels indicate pregnancy, while a drop may suggest an embryonic loss. Ultrasound remains the best method to assess uterine health, while progesterone tests are useful for identifying non-pregnancy.