Nutrition plays a key role in the reproductive capability of all animals. Under natural conditions, species have been adjusting their reproductive cycles to the availability of feed resources, allowing females to accumulate enough energy reserves to ensure reproductive success.

In intensive pig breeding conditions these natural cycles have been modified, however, the availability of nutrients and the body composition of sows remains intimately linked to a good reproductive performance.

In animal farming the profitability of all farms depends on the reproductive performance and it is considered that its basic unit is the breeding female, in the case of pigs, the sow.

The objective of any pig farm is to produce the largest number of piglets and that they acquire the greatest weight in the shortest time and at the lowest cost, that is, to produce the largest number of kilograms of meat per housed sow per year. In this sense, the most influential factor on the reproductive capacity of the sow is undoubtedly feeding. A deficient diet both in quantity and nutritionally, will result in reduced litter sizes, lower weight of piglets and higher piglets’ mortality and ultimately the failure of pig farming.

Over the years, different feeding strategies have been developed to improve the reproductive indices of sows, among which the Flushing technique should be highlighted. This feeding strategy consists on overfeeding sows for one or two weeks prior to the insemination to optimize the ovulation of the sow and thus ensure the reproductive success, especially in nulliparous and primiparous females, as well as increase the number of piglets per sow.

The mechanism of action underlying the Flushing technique consists of increased secretion of follicle stimulating hormone (FSH) and increased frequency of luteinizing hormone (LH) pulses, which stimulate the quality (size and uniformity) and number of oocytes.

The Flushing diet should contain not only a greater energy intake, but also a greater number of vitamins and minerals, such as Vit. A Vit E, Vit. 12, Cobalt and Chromium, as they have shown to have a positive effect on reproduction. Table 1 shows an example of a Flushing diet.

Several studies show that the implementation of the Flushing technique has a marked positive effect on reproduction, allowing to obtain up to 5 more piglets per breeding sow, which means a clear positive cost-benefit balance with the use of this feeding strategy and therefore in the economy of the farm.