Betaine, a natural extract from sugar beet, is used in animal nutrition to improve productive performance. Much research in the literature regarding betaine applies to finishing pigs, but there is little information published concerning the effects of betaine on reproductive traits in females breeders. When feed intake is reduced or limited (e.g. during the summer season in hot climates), pregnant and lactating sows are unable to obtain enough energy through the feed, resulting in severe body-weight loss in 3 to 4 weeks due to mobilisation of fat stores or loss of muscle mass. Even when the current litter is not affected, the size of the subsequent litter may be smaller. The effects of betaine are more pronounced when feed intake is restricted and this suggests that an advantage may be derived from its use to improve reproductive traits.