Hormone-free protocols for the control of reproduction and artificial insemination in goats

The dairy goat industry is of great economic importance to certain rural areas of the European Union (EU), especially the Mediterranean region. Its sustainability, however, is severely affected by the seasonality of goat reproduction, which leads to fluctuations in the availability of final products. Classical hormone treatments based on progestagens and eCG are the main tools employed in the effort to achieve fertility outside of the normal breeding season. They are also used to induce and synchronize oestrus and ovulation in artificial insemination programs. The food safety policy of the EU is becoming ever stricter with regard to the use of hormonal treatments for reproductive purposes, pushing livestock-raising towards ever cleaner and greener production systems. Recent advances in the use of natural methods able to generate endocrine signals that induce the ovulatory process have improved our capacity to foster reproduction in the non-breeding season. When used in a fashion appropriate for the latitude at which animals live, their breed, and the management system under which they are raised, environmental (photoperiod), nutritional and sociosexual (the male effect) signals offer alternatives to classic hormonal techniques. This affords the fragile and heterogeneous goat production sector with new opportunities. This article describes the most representative advances made in the use of the male effect as a natural method of inducing ovulation during seasonal anoestrus. Its association with other methods for optimizing responses and synchronizing induced ovulation is also discussed; such associations allow it to be used as an alternative to hormonal treatment in artificial insemination programs.