بررسي تأثير تزريق تايلوزين در دورۀ خشكي بر عملكرد و فراسنجه‌هاي خوني گاوهاي شيري، پس از زايش

Investigation of the occurrence of liver abscesses in lactating and dry Holstein cows and its effect on some blood parameters and histology of hepatocytes

با هدف بررسي تأثير تزريق تايلوزين به گاوهاي شيري در دورۀ خشكي بر توان توليدي، تركيب‌هاي شير و برخي از فراسنجه‌هاي خوني در دورۀ شيردهي بعدي، 120 رأس گاو هلشتاين با ميانگين وزن 20±720 كيلوگرم در زمان خشك كردن به تيمارهاي آزمايشي بدون تزريق تايلوزين (تيمار 1: تيمار شاهد)، تزريق 0/025 (تيمار 2: LT ) و 0/05 ( تيمار 3: HT) ميلي‌ليتر تايلوزين 20 درصد به ازاي هر كيلوگرم وزن بدن در هر روز به مدت سه روز پس از خشك كردن گاو، اختصاص داده شدند. نمونه‌هاي خون براي تعيين فراسنجه‌هاي بيوشيميايي در زمان خشك كردن گاو، روز زايش و 7، 14 و 21 روز پس از زايش گردآوري شدند. اطلاعات مربوط به توليد و تركيب‌هاي شير تا 4 ماه پس از زايش گردآوري شدند. تفاوت در غلظت پروتئين كل سرم بين تيمارها تمايل به معني‌داري داشت (0/051=P). فعاليت آسپارتات آمينو ترانسفراز (AST) و آلكالاين فسفاتاز (ALP) در گروه شاهد كمتر بود (0/05P). رخداد ورم پستان در گاوهايي كه به آن‌ها تايلوزين تزريق شده بود، به‌طور معني‌داري كمتر از گروه شاهد بود (0/05

The aim of the present study was to evaluate the incidence of liver abscess in lactating and dry Holstein cows and its effect on some blood parameters and histology of hepatocytes. The liver of 577 lactating and dry Holstein cows at the time of slaughter were examined in two abattoirs in Iran. Cow’s blood samples were collected from at the time of slaughter. Sixty healthy cows, i.e., the same number of cows with liver abscesses (which had no problem in terms of autopsy and splanchnic checking), were considered as control group according to herd and number of gestation. The livers of the cows were divided into 4 groups immediately after slaughter, liver without abscess score 0, liver with one or two small abscesses or scars; score A+, liver with two to four well-organized abscesses; score A, and liver with one or more large open abscesses, with or without adhesions; score A+. The slaughterhouse survey showed that, 10.4% (60 cows) had liver abscesses (25, 31.7 and 43.3 % for A-, A and A+). Histological results showed that in livers with abscesses, natural form of hepatocytes close to sinusoids had changed and parts of the affected tissue showed necrosis and the numbers of Kupffer cells were increased in compare to healthy livers. The concentration of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma glutamyltransferase (GGT) in the blood serum of cattle with liver abscesses with A, A and A + scores were higher than that of healthy cows (P≤0.01), while the concentration of creatine kinase (CK) in the cows affected by the abscess was lower than the healthy group (P≤0.01). Cows with liver abscesses with scores A-, A and A+ had lower concentrations of albumin and serum cholesterol than healthy cows (P≤0.01). The results of this study showed that the higher concentrations of liver enzymes and low blood concentrations of albumin and cholestrol in cows with liver abscesses may be due to the destruction of liver cells and inflammation. In conclusion, some blood parameters can be used as an indicator for assessing the status of liver abscess.