Perspectives on improvement of reproduction in cattle during heat stress in a future Japan

Abstract

Heat stress (HS) causes hyperthermia, and at its most severe form, can lead to death. More commonly, HS reduces feed intake, milk yield, growth rate and reproductive function in many mammals and birds, including the important cattle breeds in Japan. Rectal temperatures greater than 39.0°C and respiration rates greater than 60/min indicate cows are undergoing HS sufficient to affect milk yield and fertility. HS compromises oocyte quality and embryonic development, reduces expression of estrus and changes secretion of several reproductive hormones. One of the most effective ways to reduce the magnitude of HS is embryo transfer, which bypasses the inhibitory effects of HS on the oocyte and early embryo. It may also be possible to select for genetic resistance to HS. Cooling can also improve reproductive performance in cows and heifers, and probably, the most effective cooling systems currently in use are those that couple evaporative cooling with tunnel ventilation or cross ventilation. Its effect on improving reproductive performance in Japan remains to be evaluated.

The effect of heat stress on gene expression and synthesis of heat‐shock and milk proteins in bovine mammary epithelial cells

“…; Kadokawa et al . ). Within 24 h, heat stress can play a negative effect on milk production and reproduction of Holstein cattle, which induces a rapid and acute reduction (Silanikove et al .…”

Seasonal Changes in Productive and Reproductive Performance in Holstein Dairy Cows Synchronized for Estrus with the Ovsynch Protocol Under Subtropical Conditions

“…Acclimation to thermal stress also imposes physiological and metabolic adjustments associated with reduction of performance (Ispierto et al, 2007). Collier et al (2006) and Kadokawa et al (2012) detected a decrease in plasma glucose level for dairy cows in winter.…”

“…In Florida, temperatures of 29.7°C and 31.4ºC have been linked to average rectal temperatures of 39°C (mild hyperthermia) and 39.5°C (hyperthermia), respectively (Dikmen and Hansen, 2009). Rectal temperatures greater than 39°C reflect an extent of heat stress that will affect milk production and fertility (Hansen and Arechiga, 1999;West, 2003;Kadokawa et al, 2012). A THI value below 68 units generally does not cause safety problems for healthy animals; under mild discomfort and discomfort conditions (68 ≤ THI ≤ 74) heat stress begins to first cause problems; and for a THI above 75 units animals can show noticeable decrease in performance (Bouraoui et al, 2002;Hahn et al, 2003).…”

Effect of microclimatic variables on physiological and hematological parameters of crossbred cows in summer season

“…Increasing airflow and wetting frequency has significant improvement of milk production due to evaporative heat loss from the skin of dairy animals (Hillman et al, 2001;Domingos et al, 2013). Rectal temperature and respiration rate more than 39.0°C and 60 per minute indicated that, the cows are under heat stress and drastically reduced milk production and fertility (Kadokawa et al, 2012). Productivity of cows is reduced in hot environment due to poor thermoregulatory mechanism and less feed intake and poor metabolism rate (Abdelatif and Alameen, 2012;Rhoads et al, 2013).…”