INTERFACES ENTRE NUTRIÇÃO E REPRODUÇÃO DOS PEQUENOS RUMINANTES DOMÉSTICOS E SUA IMPORTÂNCIA PARA O SUCESSO NO USO DAS BIOTECNOLOGIAS DA REPRODUÇÃO

Background: A better comprehension of the relationship between nutrition and ovarian function is a fundamental key to optimize the reproductive parameters. In ruminants it is well known and recognized that nutrition is a very important mediator at the ovary level. Thus, nutritional balancing is a critical essential condition in assisted reproduction technologies when used to support improves reproductive efficiency. In many regions of Brazil, the main drawback of ovine and caprine husbandry continues to be how to sustain the nutritional status during the prolonged seasonal food shortage. In these areas the use of hormonal treatment for both estrus and ovulation synchronization is subordinate to supplementation availability or the body condition of females. Changes of nutrient intake before mating can significantly increase in the superovulatory response and modify the number and quality of embryo produced in vivo. The objective of this paper is to review the effects of nutrition on some parameters, as follicular development, oocyte quality and embryo production with particular emphasis on effects in small ruminants. Review: It was discussed the most recent available model in ewes for nutritional stimulations of folliculogenesis and regulation of metabolic factors such as insulin-glucose, leptin and IGF. Also it was introduced a novel scheme of nutritional action (acute, dynamic and static effects). Regarding the recent progress of follicular development was illustrated the effect of nutritional restriction in utero on fetal early folliculogenesis. In goats findings showed that the initial steps of follicular growth are very sensible to the food restriction applied for short period. It has been shown that energy balance is a crucial condition for assisted reproductive tools as hormone treatments for the synchronization of estrus. Hence, using several experimental data of relationships between anoestrus and body mass reduction, it was estimated a values of body condition score between 2 and 2,5 as a crucial point for the onset of nutritional anoestrus in goats and sheep. Current researches have been demonstrated in sheep that unbalanced diet, excess or restriction of feeding, interferes in the process of oocyte capacitation and its gene expression. Specifically, such short-term nutrient restriction reduced expression of glucose transporter in oocytes, and increases the leptin receptor in granulosa cells. Reduced expression of glucose transporter is essential for post-implantation embryonic development. Extra-ovarian factors, such as nutritionally mediated changes in metabolic hormones, also directly affect follicle development and oocyte quality. Therefore it is important differentiate diets optimal for follicle growth or oocyte quality and optimal for embryo survival, because these nutritional conditions may be opposite. The current trend to increase the productive levels and to develop the husbandry production is fix the nutritional management at key stages in the reproductive process, provides an effective way to develop long term feeding strategies which enable animals to maximize their fertility. Conclusion: An expressive advance of research provide in these years useful information about the nutritional effort on reproductions in small ruminants and suggest practical aspects to be considered as fundamental prerequisite to the reproduction control in goats and sheep herd.