Relationships between corn silage consumption and some blood parameters of dairy cattle

This experiment was conducted to investigate the effects of different levels (low, medium, high) of corn silage consumption on serum thyroxine, estrogen, parathyroid hormone (PTH), prolactin, albumin, cholesterol and lactate dehydrogenase (LDH) levels. It also was performed to determine the correlations among serum thyroxine, estrogen, parathyroid hormone (PTH), prolactin, albumin, cholesterol and lactate dehydrogenase (LDH) levels in dairy cattles . The experiment was conducted in an industrial dairy farm located in Ereğli district of Konya province. Holstein breed dairy cattle in third lactation (between 90–120 days of milking days) were used in the experiment. The rations were prepared according to the TMR (total mixed ration) principle using corn silage, corn flake, soybean meal, dry alfalfa hay, fractionated bypass oil, concentrated feed, wheat straw and vitamin-mineral premix available in the farm. Three different rations were prepared for the trial in the farm. The rations were prepared to include low, medium and high levels of corn silage (low: 8 kg/day; medium: 16 kg/day; high: 24 kg/day). Dairy cattle were fed with these rations for 30 days. At the end of the 30th day, blood samples were taken from caudal vein (vena caudalis) of all animals into 10 ml tubes and the samples were centrifuged in the laboratory (4000 rpm) and the serums were separated. Thyroxine, estrogen, parathormone, prolactin, albumin, cholesterol and lactate dehydrogenase (LDH) analyses were performed in serums. Low, medium and high levels of corn silage consumption in dairy cattle affected serum thyroxine, estrogen, parathormone (PTH), prolactin, albumin, cholesterol and lactate dehydrogenase (LDH) levels significantly (P<0.01). High level of corn silage consumption decreased thyroxine and albumin levels while increased estrogen, parathormone (PTH), prolactin, cholesterol and lactate dehydrogenase (LDH) levels. The correlations between serum thyroxine, estrogen, parathormone (PTH), prolactin, albumin, cholesterol and lactate dehydrogenase (LDH) levels in dairy cattle consuming low, medium and high levels of corn silage were found to be statistically significant (p<0.01). While the correlations between serum thyroxine and albumin levels and lactate dehydrogenase (LDH), parathyroid hormone (PTH), estrogen, cholesterol and prolactin levels were found to be negative, the correlations between these parameters (between thyroxine and albumin; between lactate dehydrogenase (LDH), parathyroid hormone (PTH), estrogen, cholesterol and prolactin) were found to be positive. As a result, it would be suitable 8 kg/day corn silage for dairy cattle. Keywords : Corn Silage; Dairy cattle; Lactic acid; Lactate dehydrogenase; Thyroxine; Estrogen