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Dairy farming plays an important role in the socioeconomic scenario, and several characteristics point to an enormous potential for growth in the productivity of the herd. This is a complex activity that needs to be carried out efficiently in all the links that integrate it. Moreover, due to the physiological and metabolic aspects of the animals with the aptitude for the milk production, several challenges arise, especially in the reproductive scope. In this context, breeding biotechniques appear as a good alternative to the increase in reproductive rates and genetic improvement of dairy cattle. In addition, ovarian antral follicle counts (AFC) have been studied as a way to improve the selection of females to compose reproductive programs, because it has been shown to be a factor of high repeatability over the reproductive life in the same animal. Although studies have shown controversial results regarding the relationship between AFC and fertility, it is still necessary to investigate the possible variables that may interfere with the performance of donors in each biotechnology used. Thus, this review intends to gather and discuss the relationship of AFC with physiological aspects of dairy cows, its application as a parameter of selection of animals with good fertility and, the challenges for the application of reproductive biotechniques in dairy cattle.

Folliculogenesis is a process of development and maturation of the ovarian follicles, being essential for the maintenance of fertility. In in vivo conditions, 99.9% of the follicles of an ovary do not ovulate and undergo atresia. In order to minimize this loss and to clarify the existing mechanisms, a technique was developed that allows for the in vitro follicular development. The objective of this study was to evaluate the effects of different epidermal growth factor (EGF) concentrations on the in vitro culturing of equine preantral follicles. Ovaries (n = 10) were collected from a local slaughterhouse of mares in seasonal anestrus, washed with 70% alcohol and PBS, and transported. The inner portion of the ovary was divided into 11 fragments of approximately 3 × 3 × 1 mm. A fragment of each ovary was immediately fixed in Bouin (control group). The remaining 10 fragments were individually cultured for 2 and 6 d. The medium was supplemented with different concentrations of EGF (0, 10, 50, 100, and 200 ng/mL). After cultivation, the fragments were processed and classified according to the developmental stage and morphology. In total, 1065 slides containing 6105 tissue sections were evaluated. Within 2 d of culture, there was a higher proportion of intact follicles at the EGF concentrations of 0 and 100 ng/mL (p > 0.05). After 6 d of culture, only the EGF concentration of 100 ng/mL demonstrated a difference when compared to the other treatments (0, 10, 50 and 200 ng/mL of EGF, p > 0.05). There was follicular development after 2 d at all EGF concentrations. Thus, we suggest that EGF promotes follicular survival in equines at a concentration of 100 ng/mL in in vitro cultures of ovarian fragments for 2 d. In addition, we suggest that EGF promotes follicular survival in equines at a concentration of 100 ng/mL in situ cultivation.