Effects Of Yeast Culture On Reproductive Performance Of Sows During Late Pregnancy And Lactating

The reproductive performance of sows is of vital importance to the development of the pig industry,there is a significant gap between China's current average per sow yield(PSY)and that in Europe and the United States,the shortage in nutrition and management of sows is one of the important reasons.The growth rate of late fetus and suckling piglets are very rapid,the maternal nutrition requirements are thus very high,nutrition pressures for late pregnancy and lactating sows therefore are much heavier.Practically perinatal feed intake of sows are decreased significantly,and able to cause the negative nutrient balance and weight loss of sows,which not only affects the growth of piglets,but also will prolong oestrus interval of sows.To add nutritional additives to diets to alleviate the nutritional negative balance of sows,and improve their reproductive performance and growth performance of piglets,is an acceptable nutrition strategy in the sows' production.Yeast Cultures(YC)has been proved to promote the growth and activity of rumen microorganisms in dairy cows and other ruminant animals,so as to improve the level of feed degradation in the rumen.Our previous study found that addition of YC in the growth pigs' diet could improve the colonic microbial fermentation and increase the VFA production,especially significantly increase the yield of butyric acid,suggesting that yeast culture could promote the degradation of undigested feed nutrients by hind gut microorganisms,to save a part of feed nutrient and energy for the host.Therefore this study supplemented yeast culture in diets of late gestation and lactation sows,in order to explore the feasibility of yeast culture in improving the reproductive performance of sows,by comparing the changes of the fecal microflora structure,and the changes of sows'reproductive performance.This thesis was described in the following three sections:Section 1:The feeding trials were conducted to investigate the effects of YC on the reproductive performance for late gestation and lactating sows.A total of 24 sows were blocked according to the similar day of farrowing and parity(average parity is between 2 and 6)and these 24 sows were randomly allotted to 2 groups:1)CON treatment,sows were fed in a basic diet(N= 12),and 2)YC treatment,sows were fed in a diet with basic diet +0.2%YC(N=12).Sows were fed individually and the testing time is from 85 days of gestation to 25 days of lactation(weaning).The results showed that the supplementation of YC can improve litter size,weaning number of piglets,litter weight,weaning weight and litter weight gain significantly(P<0.05).Meanwhile,compared with sows in the CON treatment,sows in the YC treatment tended to have an increased feed conversion ratio(P=0.068).It can be seen that the addition of YC to the diet of pregnant and lactating sows can improve the reproductive performance of sows to a certain extent.Section 2:The feeding trials were conducted to investigate the effects of YC on serum biochemical index and hormone level in sow for late gestation and lactating.A total of 24 sows were blocked according to the similar day of farrowing and parity(average parity is between 2 and 6)and these 24 sows were randomly allotted to 2 groups:1)CON treatment,sows were fed in a basic diet(N=12),and 2)YC treatment,sows were fed in a diet with basic diet+ 0.2%YC(N=12).Sows were fed individually and the testing time is from 85 days of gestation to 25 days of lactation(weaning).The fresh blood were collected at 85 d,100 d of gestation and 5 d,20 d of lactation.The results showed that No difference(P>0.05)in progesterone,prolactin,insulin and blood sugar levels was observed between YC treatments and CON treatment.However,insulin resistance index tended to be higher for sows in the CON treatment comparing with sows in the YC treatment on 100 days of gestation(P= 0.077)and lactation(P= 0.065).Serum leptin levels was obviously decreased(P<0.05)by adding the yeast culture on 20 days of lactation.While,there is a slight decrease(P= 0.077)for sows in the CON treatment compared with sows in the YC treatment on 5 days of lactation.Total cholesterol(P= 0.066)of sows in the YC treatment were slightly decreased.And a little decrease of NEFA levels(P= 0.066)compared with sows in the CON treatment on the 100 days of gestation was also been detected,whereas an obvious decreased(P<0.05)NEFA levels was observed on 5 days of lactation.Albumin and plasma urea nitrogen levels were decreased(P<0.05)by adding the YC on 20 days of lactation.Meanwhile,total protein levels(P= 0.08)of sows in the YC treatment tended to decreased compared with sows in the CON treatment.This study indicates that adding the YC in the gestation and lactation diets can improve litter BW gain during lactation,possibly by improving maternal protein utilization,leading to a reduction of BUN.Meanwhile,dietary yeast culture supplementation can significantly reduce the delivery of sows body fat mobilization and free fatty acid levels.Section 3:This experiment was aimed to investigate the effect of YC on the intestinal microflora in sows during gestation and lactation.A total of 24 sows were blocked according to the similar day of farrowing and parity(average parity is between 2 and 6)and these 24 sows were randomly allotted to 2 groups:1)CON treatment,sows were fed in a basic diet(N=12),and 2)YC treatment,sows were fed in a diet with basic diet+0.2%YC(N=12).Sows were fed individually and the testing time is from 85 days of gestation to 25 days of lactation(weaning).The fresh feces were collected at 85 d,100 d of gestation and 5 d,20 d of lactation.The similarity and diversity of bacteria were analyzed by PCR/DGGE technique based on 16S rDNA gene.The number of total bacteria and lactobacilli in sow feces was determined by Real-time PCR.The results showed that the YC had no significant effect on the structure of microbial flora in sow feces,and the results of diversity analysis did not reach the significant level(P>0.05).However,the addition of YC significantly increased the number of total bacteria and lactobacillus in the feces samples during the 20 days of lactation(P<0.01).Indicating that YC may promote the sows coliform bacteria growth improve its digestion of small intestine digestible feed nutrients,supplement the sows part of the energy needs,thereby reducing its body fat mobilization.