Study On The Relationships Between Omega-3 Polyunsaturated Fatty Acids Levels In Buffalo Milk On The Day Of Estrus And Lactation And Reproductive Performance

The dairy buffalo industry has received strong support from the Chinese government in recent years.However,it has long been a challenge for farm managers as the behavioral signs of estrus are not prominent and low reproductive rates in buffaloes.Omega-3polyunsaturated fatty acids（ω-3）are an essential group of fatty acids involved in a wide range of important biological processes,mainly derived from deep-sea fish oil,olive oil and algae.Buffalo milk is rich inω-3,which has been shown to have beneficial effects not only on human health,but also on the lactation and reproductive performance of the buffalo itself.However,the relationships between milkω-3 levels and lactation and reproductive performance in buffaloes during the estrous cycle have not been reported.To investigate the relationship between milkω-3 levels and lactation and reproductive performance in buffaloes on the day of estrus,28 healthy lactating postpartum Mediterranean buffaloes were designed to be kept under the same feeding conditions,all animals were administered gonadotropin-releasing hormone（Gn RH）on day 0,chlorprostaglandin(PGF_2α)on day 7 and an additional Gn RH on day 9.Artificial insemination（AI）was performed 24h after the second Gn RH injection.After PGF_2αinjection,the behaviors of buffaloes were recorded with an infrared camera for three days（d 8-d 10）.Follicular development was recorded daily by B ultrasound and pregnancy was diagnosed 45d after AI.Milk and blood samples were collected on the same day that the buffaloes were observed to be in estrus.Lactation and reproductive performance were compared between buffaloes with different levels of milkω-3（relative amount and absolute amount）on the day of estrus in terms of milk composition,milk fatty acid composition,follicle development,reproductive hormone levels,behavioral indicators and blood metabolic indicators.The main results are as follows:（1）Relationships between the relative amount ofω-3 in buffalo milk on the day of estrus and lactation and reproductive performanceFor lactation performance,buffaloes with a higher relative amount ofω-3 in milk tended to have higher milk protein yield（0.05<P<0.10）.No significant changes in milk yield or other milk composition were found（P>0.05）.Most milk fatty acid contents were significantly higher（P<0.05）and only oleic acid（C18:1）content was significantly lower（P<0.01）.In follicle development,the ovulation rate was significantly higher（P<0.05）.There were no significant changes in ovulatory follicle diameter,average follicle rate.In reproductive hormones,there were no significant changes in estradiol and progesterone levels in blood（P>0.05）.In behavioral science,standing frequency and standing time were found to be lower（P<0.05）,no significant changes in other behavioral indicators（P>0.05）.In blood biochemical indicators,no significant changes were found in triglyceride,total cholesterol,high-density lipoprotein and low-density lipoprotein levels.Among blood adipokines,no significant changes were found in leptin and adiponectin levels（P>0.05）.（2）Relationships between the absolute amount ofω-3 in buffalo milk on the day of estrus and lactation and reproductive performanceFor lactation performance,buffaloes with a higher absolute amount ofω-3 in milk tended to have higher milk lactose percentage（0.05<P<0.10）.No significant changes were found in other milk composition（P>0.05）.Most milk fatty acids were significantly higher（P<0.05）,and only stearic acid（C18:0）content was significantly lower（P<0.05）,and oleic acid（C18:1）content was found to tended to be lower（0.05<P<0.10）.In follicle development,there were significant increases in ovulation rate（P<0.01）,ovulatory follicle diameter（P<0.05）and average follicle rate（P<0.01）.In reproductive hormones,there were no significant changes in blood estradiol and progesterone levels in blood（P>0.05）.In behavioral science,standing frequency was found to be lower（P<0.05）,and no significant changes were found in other behavioral indicators（P>0.05）.In blood biochemical indicators,the trends of lower triglyceride levels and higher low-density lipoprotein levels were found（0.05<P<0.10）.Among blood adipokines,no significant changes were found in leptin and adiponectin（P>0.05）.In conclusion,buffaloes with higher levels ofω-3 in milk on the day of estrus showed some changes in milk fatty acid composition and no changes in other lactation performance.For reproductive performance,buffaloes with a higher absolute amount ofω-3 in milk on the day of estrus had an increased ovulation rate and better follicle development.In behavioral science,buffaloes with higherω-3 levels in milk on the day of estrus showed a significant reduction in standing frequency and no significant changes in estrus behaviors.This study enriches the knowledge ofω-3 levels in buffalo milk during estrus,and provides important guidance for the further use ofω-3 in buffalo breeding.