Effects Of Nutritional Levels On Puberty And Endocrine Mechanism Research In Gilts

Experimental animals of the study were gilts. A total of72Yorkshire breed gilts, every of which body weight was44.98+4.27kg, were randomly allocated to the three different feed intake level (high, middle, low).The feed intake among different nutritional levels respectively was:high trophic level group feed intake settings for trough basically not leftover material as principle, middle nutritional level group feed intake settings for90%of high trophic levels, low nutrient levels group feed intake settings for80%of high trophic level group. There were four replicates in every feed intake level and each replicate includes six gilts. The gilts were weighted, collected blood samples when the weights of gilts respectively was80kg,100kg and puberty. When gilts were100kg, young boars were used for estrus induction and teasing in gilts.Then, ELISA was applied to determine the hormone concentration in serum. This research was conducted to study the effect of feed intake level on the puberty and secretion mechanism of hormone in gilts. Thus this can determine the reasonable feeding programs of gilts.The results showed that:1) Effects of nutritional level on puberty weight, puberty age, estrus rate, reproductive performance in gilts are not significantly difference. But along with raising the level of nutrition, puberty weight gain, puberty age advanced and estrus tends to be improved.2) Nutritional level on litter size, number of live births and litter weight at birth are not significantly difference. But middle nutrient levels was as better performance, newborn litter weight of middle levels increased by37.33%than the high nutrient levels.3) Before reaching puberty, serum leptin concentration of middle nutrition levels and low nutrient levels was significantly higher than that of high trophic levels(P<0.05); when reaching puberty, serum E?, FSH of low nutrient levels were significantly higher than that of middle nutritional level group(P<0.05)Conclusions:1) High nutrient level can make puberty weight increasing, puberty age advancing and estrus rate rising. Low nutrient level can make gilts puberty weight reducing and the rate of estrus reducing. 2) Serum leptin concentration increases as dietary nutrient levels decreased. Serum leptin concentration makes estradiol, luteinizing hormone and insulin secretion increasing, make gilts reaching puberty body condition and start the estrus.3) Serum leptin concentration can be used as an important mark to determine whether the gilts can reach puberty.Integrated estrus weight, puberty, rate of estrus, serum hormone index, reproductive performance and economic benefit, the suggestion of production is that, between45kg and80kg, the gilts may obtain2.66times maintenance intake, after80kg the gilts may obtain2.42times maintenance intake for feeding, so this feeding program can reduce feed cost, but also can make the gilts starting puberty timely, obtaining the ideal puberty body condition and reproductive performance.