| Mastitis is one of the most serious factors influence the healthy development of the dairy industry, has brought the serious influence to the whole industry chain. Through the studies on dairy cows in Jiangsu Yancheng area and Yangzhou area of lactating cows in recessive mastitis detection field, using the isolation, culture and colony counting, combination of DHI production data analysis effects of calving months on recessive mastitis, and the effect of different degrees of recessive mastitis of milk composition was studied, relationship between somatic cell counts, bacterial infection mode, bacterial infection and the incidence of hidden mastitis and milk composition were determined, using low temperature long time pasteurization of raw milk, recessive mastitis in different incidence were detected and processed, focuses on the analysis of the effect of heat treatment on milk composition and fatty acid, this research includes the following test and results:1.This study explored the relationship of calving months with incidence of latent mastitis and milk production.DHI records of2,564first lactation cows was collected in an intensive dairy farms in Yancheng, Jiangsu, and the incidence of latent mastitis of these dairy cows were detected using the mastitis testing kit. The data were statistically processed using SPSS software.The results showed that:Calving month in June related with a lowest305-day milk yield, while August related with a highest yield. For other calving months, significant difference existed almost between each month and the other month. When the Calving month was on June and July, a highest incidence of latent mastitis was observed and a lowest incidence was observed on April and May. Calving month also correlated significantly with latent mastitis degree, and latent mastitis degree correlated significantly with305-day milk yield.These results recommended that a better calving month would be September or October, and thus a higher milk yield, lower latent mastitis incidence and lesser degree would be expected.2.The article is intended to study the links between pathogenic bacteria infection and mastitis. Based on the isolation and identification of bacteria and colony count method for the determination of636milk sample, including the normal breast, invisible, clinical mastitis mastitis milk. The result shows that:The ranch mastitis dominated by single bacterial infection, and with the rising in the proportion of Lactobacillus, reducing the proportion of Staphylococcus as well as increasing in aerobic, mastitis levels gradually increased.The colony in normal milk, invisible, clinical mastitis milk are compared with the positive (P<0.01). Results suggest that: with the increase of proportion of Mycobacterium and total number of bacterial colony, Level of incidence of mastitis, aerobic, percentage of Lactobacillus are positive correlation.3.To explore the relationships of the degree of mastitis, total bacteria count,and bacterial infection pattern with milk composition and somatic cell count, the identifying medium and plate counting method were used for identification of bacteria and total bacteria count, and subclinical mastitis and DHI were also tested in187dairy cows with different degree of mastitis in this experiment. The results showed that:1) Patterns of bacterial infection exerted no significant effects on somatic cell count, milk protein and fat rate (P>0.05), but had significant impact on the determination of daily milk yields (P<0.05);2) Total bacteria count had no significant effect on protein content (P>0.05), but had extremely significant effect (P<0.01) on daily milk yield, milk fat content and somatic cell count;3) Under the same bacterial infection pattern, total bacteria count had significant impact (P<0.05) on the determination of daily milk yields, somatic cell count, milk protein and fat content;4) the degree of Mastitis had significant effect (P<0.05) on somatic cell count, daily milk yield, milk fat and protein content, and the total bacteria count;5)The somatic cell count had extremely significant effect (P<0.01) on daily milk yield milk fat and protein content. These findings demonstrated that pattern of bacterial infection exerted no significant effects on somatic cell count, and the degree of mastitis and somatic cell count had significant effect on milk component. We could use somatic cell count and the total number of colonies to monitor the mastitis risks and the possible changes in milk composition.4.To explore the effect of low temperature long time to change the conventional pasteurization milk composition. This experiment using the Yangzhou University experimental farm of74lactating dairy cows, the BMT recessive mastitis test and gives the infection level, the acquisition of the milk samples of milk composition determination and PH titration, after heat treatment using low temperature long time pasteurization. The results show that:the impact of milk composition and PH change on different mastitis morbidity degree of raw milk heat treatment process of low temperature long time pasteurization was not significant (P<0.05)5.The study aimed to explore effect of subclinic mastitis degree on milk fat composition in raw and pasteurized milk.64dairy cows with mastitis were tested the degree of mastitis and their milk fatty acids were extrcted and assayed, the data were then processed using the method of single-factor variance. The results showed that:1. the keypoint of mastitis was the "+++" type, with which content of many fatty acids changed significantly;2.during pasteurization degree of mastitis affected content of almost all the fatty acids;3.pasteurization would raise the content of fatty acids C14:0and C14.1, while affected little on other fatty acids. Conclusion: these findings indicated that control of subclinic mastitis degree could stablize the content of fatty acids, and pasteurization affected little on fatty acids, except C14:0and C14:1,... |
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