Biotechnical options to reduce the effects of heat stress in dairy cows

Biotechnical approaches are aimed at directly improving fertility.

Selection of heat resistant breeds

It is well established that bos indicus breeds show better resistance to indirect negative effects of heat stress on production and reproduction performance.

In heat stress conditions zebu cows show less severe reduction in feed intake, growth rate and milk yield. In spite of this, low milk production and relatively slow growth rate makes the bos indicus breeds specially suited for extensive meat production and not for intensive dairy operations.

Embryo transfer

Embryo transfer using in vitro produced embryos or embryos derived from donors not exposed to high ambient temperatures was used with encouraging results as a means to reduce adverse effects of heat stress on fertility (Drost et al., 1999; Rutledge 2001; Al Katanani et al., 2002).

Caution should however be exercised as transfer of an embryo with non-compromised quality to a recipient subjected still to the effects of the heat stress does not eliminate negative effects on endocrine axis and uterine environment.

Moreover embryo transfer is often not an economically or technically viable option for many countries in high temperature zones.