Effects Of Pig Feed Additives With Growth-Promoting Agents On The Growth And Reproductive System Of Adolecent Male Rats

ObjectiveTo study whether the feed additives widely used in the market have effect on the growth and reproductive system of adolescent male rats,and explore the possible mechanism.Methods40 26-day-old male Wistar rats were randomly divided into four groups, including control group,low-dose group,the middle dose and the high dose group. The dosages were set as 0%,5%,15%and 30%according the pre-test.All rats can free access to water and food.Weight and food intake were recorded every four days. After 32 days,all rats were decapitated to get 4～5ml blood,and serum was collected after centrifuging.Bilateral testis and epididymis were separated,weighed and calculated.The left side testicle was preserved under -80℃;The right side testicle was preserved for pathological observation;The left side epididymis was used for sperm counting,sperm motility and aberration rate;Serum Testis testosterone(T), estradiol(E2),luteinizing hormone(LH),follicle-stimulating hormone(FSH)were measured by RIA;Lactate dehydrogenase(LDH),Acid phosphates(ACP),Alkaline phosphatase(AKP)was measured by spectrophometry.ResultsThe results showed that:1.Effects of feed additives on growth and development of the male rats 32 days after exposed feed additives,compared with the control group,rats in all trial groups decreased in body weight and liver weight significantly(P＜0.01);the viscera coefficients of liver did not change significantly.Compared with the control group,testicular weigh,epididymis weight and the viscera coefficients of testicular of the middle,high-dose group were significantly different(P＜0.01);2.Effects of food utilization on the weight of male ratsIn the experiment,food utilization in the control group,low,middle and high dose group decreased significantly,as 0.26,0.23,0.15 and 0.08,respectively.3.Effects of feed additives on the peroxidation indexes of the male ratsCompared with the control group,testicular tissue SOD,GSH activities of the middle,high-dose group decreased significantly(P＜0.05 or P＜0.01);MDA activities increased significantly(P＜0.05 or P＜0.01).4.Effects of feed additives on the reproductive indexes of the male ratsWith the increasing dose of feed additives,lactate dehydrogenase(LDH) activities were in decreased and acid phosphatase(ACP)activities were increased in the testicular tissue,but the AKP activities have no changes.Compared with the control group,rats in all trial groups decreased significantly in LDH activities(P＜0.01) after the treatment;ACP activities of middle-dose group and high-dose group increased significantly(P＜0.05 or P＜0.01).Compared with the control group,sperm counting and sperm motility decreased significantly(P＜0.01);sperm aberration rats among all trial groups didn't have significantly differences(P＞0.05).5.Effects of feed additives on serum gonadal hormones levels of male ratsCompared with the control group,rats in all trial groups had lower T levels (P＜0.05 or P＜0.01)after the treatment;Serum FHS and E₂ levels in all trial groups were higher than control group(P＜0.01);serum LH levels in all trial groups show no statistical differences(P＞0.05).ConclusionShort-term contacted with certain animals feed additives can significantly reduce animal's weight,affect the rats' sperm quality,testicular function,thus affect the development of adolescent reproductive organs in male rats,and impare reproductive system.The possible mechanism might be the body lipid peroxidation or the hypothalamus-pituitary-gonadal axis being interfered.