EFFECTS OF ZEARALENONE OR GLUCOSINOLATES IN THE DIET ON REPRODUCTION IN SOWS - A REVIEW

This review deals with the effects of intake of two important kinds of antinutritional factors on sow reproduction: a mycotoxin, zearalenone, and glucosinolates from rapeseed meal. Emphasis is given to their way of action on which numerous works were undertaken during the last years. Unlike a nutrient imbalance whose effects generally appear at long-term and are difficult to cure, the influence of antinutritional factors is observed rapidly, concerns many parameters and disappears when their intake is disrupted. Zearalenone, which is produced by some Fusarium strains, contaminates cereals harvested in damp conditions. It is characterized by its oestrogenic properties which induce vulvovaginitis in premature gilts, anoestrus in cycling females or delayed return into oestrus after weaning of the sows. During pregnancy, zearalenone reduces embryonic survival when fed beyond a threshold level, and sometimes decreases foetal weight. It could affect uterine environment by decreasing LH and progesterone secretion and modifying the morphology of uterine tissues. Rapeseed meal contains glucosinolates whose some by-products have anti-thyroidic properties. During pregnancy, they induce a thyroid hypertrophy in sows and foetuses. Foetuses are especially sensitive since their T4 level in plasma and their liveweight before birth decrease in relation with the glucosinolate level in maternal diet. All harmfull consequences are avoided when glucosinolate level in the diet remains below 2 mu M/g. Thus, use of rapeseed cultivars with a very low glucosinolate content, obtained through selection, allows the feeding of reproductive sows with diets containing high levels of rapeseed meal.