Effects Of Altrenogest Treatments On Estrus Regulation And Subsequent Reproductive Performance In Weaned Sows

It is a critical moment for the transformation and upgrading of pig breeding industry in China.The number of pig farms is decreasing,the scale is expanding,and sow productivity is continuously improving.However,compared with developed countries in Europe and America and other large pig breeding countries,there is still a big gap,especially in batch production.The synchronous estrus technology has been greatly popularized in the grouping of gilts,and has also achieved good results.To a certain extent,it has promoted the process of batch production of pig farms,helped pig farms to achieve three-week batch,four-week batch,five-week batch and other modes of production.However,in the transitional stage,there is few research on how to make the original disorganized weaned sows to achieve batching.On the basis of batch production,maybe the production rhythm is disrupted and cannot be produced in batches,such as early weaned caused by PED.It is necessary to batch the production of weaned sows by synchronous estrus technology.It is particularly important to study estrus inhibition of altrenogest on weaned sows.In this study,weaned sows were fed with different dosages 16mg（A₁）、20mg（A₂）、28mg（A₃）and different days 7 days（B₁）,14 days（B₂）of altrenogest to explore the effect of weaned sows on estrus rate,estrus interval,return to estrus rate,conception rate,farrowing rate and farrowing performance;by measuring the changes of blood physical and chemical indexes and serum reproductive hormones of sows,it provides necessary data support for the application of altrenogest in batch production of sows.Through scientific analysis methods,the main results are as follows:1.During altrenogest feeding period,there were no weaned sows show estrus in each treatment group,and the rates of estrus inhibition were 100%.2.After altrenogest feeding program,the estrus rate within 7 days in group A₂B₁was100.00%,which was the same as that in control group and significantly higher than that in the other treatment groups（P<0.05）.The estrus rate of sows in A₃B₂group was 81.00%and was the lowest group,which was significantly lower than that in other groups（P<0.05）.Sows in all treatment groups showed delayed estrus,and the heat interval in group A₂B₁was4.78 days,which was a little higher than that in A₀B₀group（P>0.05）,but was significantly lower than that in the other treatment groups（P<0.05）.3.In the control group A₀B₀,the farrowing rate was 85.70%,and the number of piglets total born was 12.72±1.52.In the treatment group,the farrowing rate of A₂B₁was 90.50%,and the number of piglets total born was 12.84±1.16,which were higher than those in the control group,but the difference was not significant（P>0.05）.The farrowing rate of A₃B₂in treatment group was 100.00%and the number of piglets total born was 13.23±1.87,which were significantly higher than those in control group（P<0.05）.Compared with the control group,there were no significant differences in the number of stillbirths and mummies in all treatment groups（P>0.05）.4.The results of serum hormone levels showed that testosterone,estradiol and progesterone were significantly decreased in weaned sows after altrenogest feeding program（P<0.05）.FSH,LH and prolactin had no significant changes,but FSH and LH in all treatment groups were lower than those in normal weaned sows.Altrenogest feeding had no significant effect on the blood physical and chemical indexes of weaned sows,and had no adverse effect on the normal metabolism of sows.5.In the treatment groups which fed altrenogest for 7 days,the estrus rate and concentration ratio of weaned sows were better than those of weaned sows fed altrenogest for14 days,and the weaned sows which fed 20mg altrenogest per day had the best farrowing performance.The recommended altrenogest dosage for 7 days feeding is 20mg/d.6.In the treatment group which fed altrenogest for 14 days,the weaned sows showed a significant delay in estrus after altrenogest feeding,but had good farrowing performance.Sows fed 28mg altrenogest per day had the highest farrowing rate and the best litter size.The recommended altrenoges dosage for 14 days feeding is 28mg/d.