The SCC Variation In Milk And The Effect Of Exogenous Melatonin On SCC And Estrus Synchronization Of Buffaloes In Summer

The present study investigated the relationship between the factors?month and parity?and the somatic cell count?SCC?in buffalo milk,and the effects of dose and times of exogenous melatonin?MT?administration on ovarian activities and milk somatic cell count in buffaloes,as well as plasma hormone levels detected by ELISA technique in order to provide a better scheme that MT decreased SCC in milk and improve ovulation rate and conception rate in summer-stressed buffaloes.1.Effect of the month and parity on SCCData on DHI?Dairy Herd Improvement?record in a buffalo farm during in 2012 to2017 were analyzed by means of month and parity on SCC.Because of the distribution of SCC data were skewed,SCC data were converted into somatic cell score?SCS?for analysis.Results:Month and parity had a significant influence on SCS?p<0.05?,respectively,and SCS was the highest in August,and lowest in May.Meanwhile,the buffalo sample size of SCC>400,000/ml was the largest from June to August,the second was in winter.Besides,the SCS increased with the parity grown.There were significant differences in SCS between 1-3 parity?p<0.05?.2.Effect of MT dose on anti-oxidant activities and immune levels in lactating buffaloesA total of 20 crossbred buffaloes?SCC>500,000/mL?divided into low-dose group?n=10?and high-dose group?n=10?which were subcutaneous injected with 4.68mg and20mg of MT for 4 consecutive days,respectively.And SCC in milk samples and the plasma anti-oxidant activities and immunological indexes were detected.Results:After MT treatment,SCS in high-dose and low-dose group both were significantly lower than that of the pre-injection?p<0.05?,However,there was no significant difference between the two groups?p>0.05?.In addition,it was found that number of sub-health crossbred buffaloes with high-dose group?SCC>500,000/mL?was 10%higher than that of low-dose group by observing the number of nursing buffalo on the 11^th day after the treatment.The concentrations of MT,SOD and IgM in plasma were significantly increased?p<0.05?.Therefore,subcutaneous injection of melatonin for 4 consecutive days significantly reduced SCC and enhanced the immunity and anti-oxidant activity in milk by improving the concentrations of SOD and IgM in plasma during summer.3.Effect of MT treatment on the ovarian activities in buffaloesA total of 30 crossbred buffaloes divided into three groups randomly?T1,T2 and Control,n=10 each group?.Buffaloes in T2 received single subcutaneous injection of MLT at 18 mg/50 kg body weight,buffaloes in T1 received subcutaneous injection of MLT for 3 consecutive days at in total 18 mg/50 kg body weight,whereas buffaloes in control group were administered with while normal saline.All animals were administered with 200ug GnRH analogue on day 4 and 0.5 mg PGF_2a on day 11,200ug GnRH analogue on day 13.TAI was performed after the second GnRH analogue treatment.The follicular development was recorded twice daily with B ultrasound,and the pregnancy was diagnosed after 45 days.Results:After the subcutaneous injection of melatonin,the concentration of SOD,MT and IgM in the treatment group were significantly higher than those of control group?p<0.05?.After PGF_2a injection,Median Survival time of dominant follicle?only have 50%of the survival time of dominant follicle?in subcutaneous injection of melatonin group was longer than the control group,the average of follicular rate?1.8mm/d and 0.7 mm/d?and the large follicle diameters in subcutaneous injection of melatonin group was higher than the control group?p<0.05?.In addition,the ovulatory follicle diameters,ovulation rate,the number of large follicles and the pregnancy rate were significantly higher than those groups T1 and control?p<0.05?.Therefore,subcutaneous injection of melatonin were able to produce a higher levels of SOD and IgM,two treatment groups combined with GPG scheme could promoted the follicular development and ovulation,but a single injection group could significantly increased the number and diameter of ovulatory follicle,and improved ovulation rate and conception rate in the crossbred buffaloes during the non-breeding season.