Effects Of 25-hydroxyvitamin D₃ On Humoral Immunity And Production Performance In Different Gestation Stages Of Sows And Piglets

Vitamin D₃is one of the essential nutrients in animal growth and development.It can promote calcium and phosphorus metabolism,improve the vitality of germ cells and enhance the immune ability of animal.As the pig industry gradually becoming large-scale and intensive,pigs are kept in the environment which cannot get sunlight,which makes pigs cannot synthesize vitamin D₃by themselves.Combined with insufficient dietary vitamin D₃content,pigs are likely to face the situation of vitamin D₃deficiency.Therefore,it is urgent to find an efficient and safe vitamin D₃additive.As the metabolite of vitamin D₃and the main circulation form in animals,25-OH-D₃has the advantages of high absorption and transport efficiency and good safety,but there are few reports on the application effect in pig industry.Five different batches of sows with similar health status were used as treatment animals in this experiment.At the same time,sows were fed diets supplemented with25-OH-D₃at the ratio of 50μg/kg.At the beginning of the experiment,sows in each batch were respectively at the 0th,28th,56th,84th,114th day of gestation,and were recorded as treatment group 1,treatment group 2,treatment group 3,treatment group4 and control group.The results are as follows:1.Effects of dietary supplementation of 25-OH-D₃on performance of gestational sowsMethods:The conception rate and abortion rate of sows in each group were recorded before delivery,and the number of total piglets,live piglets,weak piglets,stillborn piglets and mummy piglets.After delivery,the survival rate of newborn piglets and weaned piglets were calculated and recorded.Enzyme linked immunosorbent assay（ELISA）was used to detect the content of 25-OH-D₃,calcium and phosphorus in serum of sows at 0th,84th day of gestation,delivery and weaning time.The conception rates of treatment groups 2,3 and 4 were significantly higher than control group（P<0.05）.The abortion rate of sows in treatment groups was significantly lower than control group（P<0.05）.The total size of treatment group 1,2and 4 was significantly higher than control group（P<0.05）,and the total size of treatment group 1 was the highest.The weak size of treatment groups 2 and 3 was significantly lower than control group（P<0.05）.There were no significant differences in the number of stillbirths and mummified births in treatment groups compared with the control group（P>0.05）.The number of live offspring in treatment groups 1 and 2was significantly higher than treatment groups 3,4 and control group（P<0.05）,and the number of live offspring in treatment group 1 increased the most.Dietary25-OH-D₃had no significant effect on the survival rate of newborn piglets（P>0.05）,but significantly increased the survival rate of weaned piglets in treatment groups（P<0.05）.The serum 25-OH-D₃concentration,serum calcium and serum phosphorus levels of sows in treatment groups were significantly higher than those in control group（P<0.05）,and the increases of 25-OH-D₃and serum calcium concentrations in treatment group 1 were the most obvious.Conclusion:Adding 25-OH-D₃can improve the performance of sows,and adding 25-OH-D₃at the beginning of gestation has a more obvious effect on the performance.2.Effects of dietary 25-OH-D₃on specific immunity of pregnant sowsMethod:Using ELISA to detect sows classical swine fever,pseudorabies,porcine reproductive and respiratory syndrome,porcine circovirus diseases,Mycoplasma pneumonia of swine antibody levels and serum Ig G concentration at the0th,84th day of gestation,delivery and weaning stage.Results:The antibody level and serum Ig G concentration of CSF in treatment group 1,2 and 3 were significantly higher than control group（P<0.05）,and the increase of antibody level and serum Ig G concentration in treatment group 1 was most obvious.The level of pseudorabies antibody and serum Ig G antibody in treatment groups were significantly higher than control group（P<0.05）;The level of reproductive and respiratory syndrome Ig G antibody in treatment groups 1 and 2 was significantly higher than treatment groups 3and 4 and control group at delivery and weaning（P<0.05）,but there was no significant difference in the concentration of reproductive and respiratory syndrome Ig G antibody among all groups（P>0.05）.The antibody level of porcine circovirus disease in treatment group 1 was significantly higher than control group at different periods（P<0.05）,the antibody level of treatment group 2 and 3 at weaning was significantly higher than that in control group（P<0.05）,and the Ig G antibody concentration of porcine circovirus disease was not significantly different among all groups（P>0.05）.Dietary supplementation of 25-OH-D₃had no significant effects on the antibody level and serum Ig G concentration of Mycoplasma pneumonia（P>0.05）.Conclusions:Dietary supplementation of 25-OH-D₃can improve the specific immunity of sows against some common pig diseases,and the effect of dietary supplementation of 25-OH-D₃on specific immunity of sows at the beginning of gestation is more significant than supplementation during gestation.3.Effects of dietary 25-OH-D₃on Growth performance and specific immunity of pigletsMethods:The body weight and body length at birth and weaning time of piglets in each group were recorded.ELISA was used to detect the content of 25-OH-D₃,calcium and phosphorus in serum of piglets at birth and weaning time,the antibody levels of classical swine fever,pseudorabies,porcine reproductive and respiratory syndrome,porcine circovirus disease and Mycoplasma pneumonia at weaning time,and the serum Ig G concentration.Results:There was no significant difference in average birth weight of piglets in treatment group compared with control group（P>0.05）,average weaning weight of piglets in treatment group 1,2 and 4 was significantly increased compared with control group（P<0.05）,and average weaning weight of piglets in treatment group 1 and 2 was significantly increased.Compared with control group,the content of 25-OH-D₃in serum of piglets in treatment group was significantly increased at birth（P<0.05）;The serum calcium concentration of piglets in treatment group 1 and 2 was significantly higher than that in control group at weaning（P<0.05）;Serum phosphorus concentration of newborn piglets in treatment group was significantly higher than that in control group,and blood phosphorus concentration in treatment group 1 was significantly higher than that in control group at weaning（P<0.05）.Compared with the control group,the antibody level of piglets in treatment group was significantly increased（P<0.05）,and the antibody level of piglets in treatment group 1 was significantly increased compared with the control group（P<0.05）.Compared with the control group,the serum Ig G antibody concentrations of swine fever,porcine reproductive and respiratory syndrome and porcine pseudorabies in treatment groups were significantly increased（P<0.05）.Conclusions:Dietary supplementation of 25-OH-D₃for sows can promote the growth of piglets and enhance the specific immunity of piglets,and the effects of dietary supplementation of 25-OH-D₃at the beginning of gestation of sows on the growth performance and specific immunity of piglets are more significant than supplementation during gestation.