Natural shade from integrated crop–livestock–forestry mitigates environmental heat and increases the quantity and quality of oocytes and embryos produced in vitro by Gyr dairy cows

This study aimed to evaluate the effect of natural shade from integrated crop–livestock–forestry (CLF) on the comfort of lactating Gyr cows, as well as their oocyte and embryo quantity and quality. Twenty animals were separated into two experimental groups: grazing under full sun (control) and under natural shade provided by the CLF system. Meteorological variables and bioclimatic indicators, rectal and animal surface temperatures, milk quantity and quality, follicle number, oocyte quantity and quality, and in vitro embryo quantity and quality were measured. Data were collected in the rainy season (from November until April) and compared with data obtained in the dry season (from May until October). During the dry season, the natural shade from CLF maintained the dry-bulb temperature at 6.9°C, 5.9°C, and 4.3°C lower than that in the full sun in August, September, and October, respectively. The environment with tree shade presented a black globe-humidity index (BGHI) 3%–7% lower than that in the full sun environment. In the dry season, the most challenging period for animals, the microenvironment produced by the shade of trees reduced the surface temperatures of the udder, rump, and area around the eye of cows by 1.0°C–1.8°C compared to those of animals in the full sun area. Rectal temperature and milk production were not influenced by treatment. However, the higher thermal comfort influenced the reproduction of cows; they presented a higher number of ovarian follicles (37.05 ± 3.40 vs. 31.73 ± 3.86), higher number of total oocytes (11.41 ± 4.69 vs. 6.5 ± 2.60), and more viable oocytes (6.27 ± 3.36 vs. 3.45 ± 1.38) per animal than cows directly exposed to the sun during the dry season. Gyr cows maintained under shade presented more transferable embryos per cow than did those in the CLF environment. CLF systems are a technological alternative to provide improved microclimate within grasslands and thermal comfort to dairy cows, including zebu cows.