Study On The Correlation Between Trace Element Copper And Dairy Cow Recessive Mastitis

Subclinical mastitis has become one of the most difficult diseases in intensive dairy farms,so prevention of subclinical mastitis has become the focus and difficulty of dairy farms at this stage.Copper(Cu)is a necessary trace element in dairy cows.Copper participates in the body's antioxidant defense in the form of superoxide dismutase(SOD)and ceruloplasmin.Copper deficiency can greatly inhibit cellular immunity and humoral immunity.Therefore,the purpose of this experiment is to detect the copper content,somatic cell number,antioxidant capacity,immune ability and milk quality of dairy cows under the same background.The correlation between copper level and physiological indexes of dairy cows is analyzed by data analysis,and then the relationship between copper and subclinical mastitis of dairy cows is found out,which provides a reference for the prevention of subclinical mastitis of dairy cows through nutritional immunity.The experimental animals were selected from B pasture cows in Heilongjiang area.They were fed and managed at regular level.TMR mixed diets were fed freely.According to DHI data of dairy farm,50 lactating cows with similar body weight,fetal times(2-3),pre-lactation,body condition and feeding management were randomly selected.Blood was collected and serum was separated.Microwave digestion was used for pretreatment to meet the detection standard of copper.Then the copper content was detected by ICP plasma emission spectrometer.Milk was collected to detect SCC and milk ingredients.According to the level of serum copper from low to high,they were divided into 5 groups on average.Blood serum was collected again for the detection of SOD,T-AOC,IL-1,IL-2,IL-6 and TNF-alpha by ELISA.The relationship between copper and subclinical mastitis in dairy cows was analyzed by data analysis.The experimental results are as follows:(1)The incidence of subclinical mastitis in dairy cows was 32%.Somatic cell count increased with the increase of serum copper level,but no obvious difference(P > 0.05).Pearson analysis showed that there was no correlation between serum copper level and SCC in dairy cows.Normal copper levels had no effect on the incidence of subclinical mastitis.(2)There was a low positive correlation between serum copper level and IL-2 in lactating dairy cows(R= +0.355,P=0.011).IL-2 in serum of lactating dairy cows increased with theincrease of copper level.In addition,there was a significant difference between the experimental group 1 and the experimental group 5(P < 0.05).(3)There was no correlation between serum copper level and IL-1 in lactating dairy cows(R= +0.215,P=0.133).There was no significant difference in serum IL-1 levels among the experimental groups.There was no correlation between serum copper level and TNF-a in lactating dairy cows(R=-0.185,P=0.198).There was no significant difference in serum TNF-alpha levels among the experimental groups.There was no correlation between serum copper level and IL-6 in lactating dairy cows(R= +0.020,P=0.892).There was no significant difference in the level of IL-6 in serum of lactating dairy cows among the experimental groups.(4)There was a low positive correlation between serum copper level and SOD in lactating cows(R= +0.373,P=0.048).SOD in serum of lactating cows increased with the increase of copper level.However,there was no significant difference in SOD levels among the experimental groups(P > 0.05).There was no correlation between serum copper level and T-AOC in experimental dairy cows(R= +0.253,P=0.077).There was no significant difference in serum T-AOC levels among the experimental groups(P > 0.05).(5)The serum copper level of lactating dairy cows had little effect on lactose rate and milk protein rate(P > 0.05).However,the milk fat rate of experimental group 4 was significantly higher than that of experimental group 1 and 2(P < 0.05).Milk yield showed a decreasing trend,but the difference was not significant(P > 0.05).Pearson analysis showed that serum copper level was not correlated with milk yield(R=-0.215,P=0.056).In conclusion,within the normal range of serum copper level,serum copper level is not correlated with the number of somatic cells in dairy cows;serum copper level is positively correlated with IL-2 and SOD at a low level.Increasing serum copper level in dairy cows will enhance the antioxidant capacity and immune capacity of dairy cows;appropriate improvement of serum copper level in dairy cows will improve the milk fat rate of dairy cows remains to be further studied.