| Ketosis of dairy cows was due to negative energy balance caused by the dysbolism of carbohydrate and lipide, which leaded to the accumulation of ketones in the blood and discharged from urine, milk and breath. Ketosis mainly occurred in high producing dairy cows which characterized by low level of blood sugar. In recent years, with the increasing of average milk yield, ketosis was more likely to occure in dairy cows in ealy lactation period. Ketosis can be divided into clinical and subclinical ketosis according to cows with or without clinical symptoms. Subclinical ketosis cows were lack of significant symptoms and mainly charactered by the envaluated ketone body in blood, milk and urine and decreased blood sugar. As subclinical ketosis did not lead to obvious clinical symptoms, it caused more serious potential hazards. Mastitis was a common disease in dairy cows. But there was none reports about the relationship between subclinical ketosis and mastitis in dairy cows internal. This study was mainly about the impact of subclinical ketosis on mastitis, antioxygen and immunity function, which provided evidence for the prevention of disease in dairy cows.1The influence of subclinical ketosis on mastitis69subclinical ketosis cows were chosen from156holstein cows as the test group (1.0mmol/L≤BHBA<2.6mmol/L, SCC <200,000/mL). The control group was paired according to age, parity, milk yield and days in milk with69cows (serum BHBA<1.Ommol/L, SCC<200,000/mL). Milk was sampled weekly for the monitering of SCC. The milk samples of the4mammary glands in mastitis cows (SCC>200,000/mL) were sterile collected for the isolation and indentification of mastitis pathogens separately. The result indicated that the incidence of mastitis in the test group was43.48%, while the control group was31.88%. But the difference was not significant (P>0.05). Mastitis of test group was mainly onset during the third to sixth week after parturition, while the control group mainly onset during fifth to eighth week after parturition. Mastitis mainly occured one to three weeks later than subclinical ketosis, and the proportion that outbreak in the three weeks was73.33%. There was no different in the composition of the mastitis pathogen (P>0.05)2The influence of subclinical ketosis on antioxygant function12cows(SCC<200,000/mL) in test group and control group of the test were chosen pairly according to parturition time,age, parity and milk yield from test a. The cows were on the fourteenth day after parturition in the test. Blood was simple to centrifugate serum for the analysis of the levels of β-hydroxybutyric acid (BHBA), acetoacetate(ACAC), total antioxidant capacity (T-AOC), glutathion peroxidase(GSH-PX), superoxide dismutase(SOD), catalase(CAT), malonaldehyde(MDA) and nitric oxide (NO) in the serum. The level of T-AOC in the serum of test group was significantly lower than the control group(P<0.05). But the levels of GSH-PX, MDA and NO in the serum of test group was significantly higher than the control group (P<0.05). There was a significant positive correlation between plasma ACAC and BHBA (P<0.05). The correlation of ACAC and GSH-PX shown to be significantly positive (P<0.05). There was also a significant positive correlation between NO and ACAC level (P<0.05). The correlation of T-AOC and MDA shown to be significantly negative (P<0.05)3The influence of subclinical ketosis on the index of hematology10cows(SCC<200,000/mL) in test group and control group in the test were chosen pairly according to parturition time,age, parity and milk yield from test a. The cows were on the fourteenth day after parturition in the test. Blood was simpled for the analysis of red blood cell count (RBC), hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), RBC distribution width (RDWC), white blood cell count (WBC), lympholeukocyte (LYM), monocytes (MON), neutrophil (NEU), blood platelet count (PLT), platelet hematocrit (PCT), mean platelet volume (MPV), platelet distribution width (PDWC). The results show that MCHC was significantly higher in the subclinical ketosis cows than the control group (P<0.05). But RDWC, WBC, LYM and NEU was significantly lower in the test group (P<0.05). MPV was significantly decreased in subclinical ketosis cows (P<0.01)4The influence of subclinical ketosis on the immune function Nine subclinical ketosis cows (1.0mmol/L≤serum BHBA<2.6mmol/L) that were on the fourteenth day after parturition were selected as test group from43Holstein cows that parturition in five weeks. The control group (serum BHBA<1.0mmol/L) which contained nine healthy cows was paired according to days in milk, age, parity and mild yield. Blood was simpled for the analysis of phagocytosis function and chemotaxis function of neutrophils, lymphoryte transformation rate and the levels of immunoglobulin G, interleukin-2, interleukin-8and γ-interferon in the serum. The results showed that the rate of phagocytosis and the chemotactic index of neutrophils in the blood of the subclinical ketosis cows were significantly lower than the control group (P<0.05).Lymphocyte transrormation rate was significantly lower than the control group (P<0.01). Serum level of γ-IFN was significantly lower than the control group (P<0.05). The levels of serum IL-2and IL-8did not significantly decerase(P>0.05). |
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