| Zearalenone (ZEA) is one kind of mycotoxin produced by Gibberella zeae and Fusarium, which can be commonly found in corn, wheat and oat. It is widely acknowledged that ZEA pollution is widespread in Chinese feeds industry. Toxicity of ZEA in animals is extensive, and it can mainly lead to estrogen hyperthyroidism symptoms such as red and swollen vulva and breasts, premature estrus, repeat breeding failure in gilts and miscarriage, stillbirth in pregnant sows. Soy Isoflavones (ISO) extracted from soybean also has estrogenic effects and exhibits many beneficial biological functions such as anti-cancer, anti-oxidation and enhancing immunity. It must be noticed that ZEA and ISO coexist in the corn and soybean meal-based diets. Both of the ZEA and ISO possess the estrogen-like effect, and they may show a combined effect on animals, but which kinds combined effects of ZEA and ISO on gilts remain unreported. Therefore, this trial is been conducted to study the combined effects of ZEA and ISO on growth and reproduction in gilts.The feeding experiment arranged in a factorial designation (3×3) with their interaction effects considered.90 healthy Duroc×Landrace×Lorkshire gilts in the same age and.same weight (75 days,27 kg B.W.) were randomly divided into 9 groups per 5 treatments with 2 replicates. The gilts were fed with the diets with 0,0.5 mg/kg,2 mg/kg ZEA and 0,300 mg/kg,600 mg/kg ISO in a period of 21 days in the feeding trial. Average daily gain, feeds intake was recorded during the trial, and then blood samples were collected every 7 days to analyze the reproductive hormone levels. Width of vulva and weight of uterus were measured after slaughtering gilts on 21 days, followed uterus, vagina and ovary separated to take histological examination which aims to study the combined effects of ZEA and ISO on growth and reproduction in gilts.The results showed that ZEA and ISO alone had no significant effect on daily feeds intake in gilts (P>0.05), high concentrations of ISO could significantly reduce the average daily gain (P<0.05), ZEA and ISO only had a combine effect to improve feed conversion ratio significantly (P<0.05), and had no significant effects on the daily weight gain feed intake. The serum FSH level significantly increased in ISO groups (P<0.05) in the whole trial, and this rising trend significantly lowered by the combined effect of ZEA and ISO the in 14 days,21 days (P<0.05); ZEA could significantly reduce LH level in serum in 14,21 days, (P<0.05) and ISO could significantly reduce the level of sow serum LH only inl4 days of this feeding trial (P<0.05). Meanwhile, no interaction effects of ZEA and ISO on serum LH levels were observed throughout the trial period. E2 levels in serum significantly decreased in the first 14 days in ZEA groups (P<0.05), but E2 levels significantly increase on 7 days and significantly increase 14 days in ISO groups (P<0.05). There was no interaction effect on the E2 level in serum of ZEA and ISO during the entire test Any concentrations of ZEA and ISO alone could result in significant weight gain of uterus and width increase of vagina in gilts (P<0.05); the combined effect of ZEA and ISO significantly lowered uterus weight gain and width increasing of vagina due to ZEA (P<0.05).These results suggested that ZEA and ISO had little effect on growth performance in gilts; but exhibiting a broad impact on reproductive hormones and organs indicators, showing obvious promoting estrogen-like effects. The antagonistic effect of ZEA and ISO on reducing estrogen promoting effect of on animals can be seen from this trial. |
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