亚临床型乳腺炎对泰国杂交泌乳奶牛原料乳蛋白质组成和蛋白酶活性的影响。
The influence of subclinical mastitis on the protein composition and protease activities of raw milk from lactating Thai-crossbred dairy cows.
作者信息
Tiantong Attapol, Eardmusic Sirichai, Arunvipas Pipat, Lee Jai-Wei, Inyawilert Wilasinee
机构信息
Faculty of Animal Sciences and Agricultural Technology, Silpakorn University, Phetchaburi IT Campus, Cha-Am, Phetchaburi, 76120, Thailand.
Department of Large Animal and Wildlife Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen Campus, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
出版信息
Vet World. 2023 Jun;16(6):1363-1368. doi: 10.14202/vetworld.2023.1363-1368. Epub 2023 Jun 17.
BACKGROUND AND AIM
Mastitis in dairy cattle is associated with a high rate of morbidity and death, which has major implications for milk production and quality. This study aimed to investigate the protein component and the activity of matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) in raw milk samples with different testing scores determined using the California mastitis test (CMT).
MATERIALS AND METHODS
Thirty cows were employed in the study, and milk from each quarter was tested for subclinical mastitis (SCM). According to the results of CMT, raw milk samples were classified into five categories: Healthy (score 0), trace (score T), weakly positive (score 1), distinctly positive (score 2), and strongly positive (score 3) for somatic cell count (SCC). The total milk protein was analyzed using the Bio-Rad protein assay, and the milk protein composition was determined using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis technique. In addition, gelatin zymography was used to evaluate changes in proteolytic abilities.
RESULTS
Milk samples with CMT scores of 1 and 3 had the highest total milk protein levels (32.25 ± 12.60 g/L and 32.50 ± 7.67 g/L, respectively), while the samples from healthy cows (CMT score 0) were only 6.75 ± 1.64 g/L. Globulin and lactoferrin were significantly increased in samples with a CMT score of 3 compared with those with other CMT scores. The bovine serum albumin level in samples with a CMT score of 2 was significantly (p < 0.05) higher than those with other CMT scores. No significant differences in casein abundance were found among samples with different CMT scores. Results from analysis of proteolytic activities demonstrated that the level of MMP-9 in samples with a CMT score of 3 was significantly (p < 0.05) higher than those with other CMT scores.
CONCLUSION
The protein content and gelatinolytic activity of milk were drastically altered by the number of SCC, mainly due to SCM.
背景与目的
奶牛乳腺炎与高发病率和死亡率相关，这对牛奶产量和质量有重大影响。本研究旨在调查使用加利福尼亚乳房炎检测法（CMT）确定的不同检测评分的原料奶样品中基质金属蛋白酶-2（MMP-2）和-9（MMP-9）的蛋白质成分及活性。
材料与方法
本研究选用30头奶牛，检测每个乳腺的牛奶是否患有亚临床乳腺炎（SCM）。根据CMT结果，将原料奶样品分为五类：体细胞计数（SCC）健康（评分0）、微量（评分T）、弱阳性（评分1）、明显阳性（评分2）和强阳性（评分3）。使用Bio-Rad蛋白质测定法分析总乳蛋白，并使用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳技术测定乳蛋白组成。此外，采用明胶酶谱法评估蛋白水解能力的变化。
结果
CMT评分为1和3的牛奶样品总乳蛋白水平最高（分别为32.25±12.60 g/L和32.50±7.67 g/L），而健康奶牛的样品（CMT评分0）仅为6.75±1.64 g/L。与其他CMT评分的样品相比，CMT评分为3的样品中球蛋白和乳铁蛋白显著增加。CMT评分为2的样品中牛血清白蛋白水平显著高于其他CMT评分的样品（p<0.05）。不同CMT评分的样品中酪蛋白丰度无显著差异。蛋白水解活性分析结果表明，CMT评分为3的样品中MMP-9水平显著高于其他CMT评分的样品（p<0.05）。
结论
牛奶的蛋白质含量和明胶水解活性因SCC数量而发生显著变化，主要是由于SCM。
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