The effects of supplemental organic zinc on some production and blood parameters in transition dairy cows

This study was conducted to determine the effects of organic zinc on milk yield and some blood parameters related with liver fatty acid metabolism and some reproductive parameters in transition dairy cows. Twenty primiparous cows were used as study material. Cows assigned into two groups as control (K) and treatment(Ç). Groups were similar in live weight, parity and body condition score. Experimental part of the study has begun 3 weeks before parturition and ended at 3 weeks after parturition. All cows were consumed same diet. Organic zinc (5 g/day per head, Optimin, Throuw Ntr) orally administrated to cows in group Ç shortly after the morning milking. All feeds in diet were analyzed for crude cellulose, protein, ether extract, ash and dry matter according to Weende Analysis Systems, besides ADF and NDF according to Van Soest method. Blood samples were collected via vena jugularis from all cows on -21, -14, -7, 0, 7, 14, 21 days according to parturition and analyzed for total cholesterol (Chol), Triglycerides (TG), High density lipoproteins (HDL), Low density lipoproteins (LDL), BHBA (Betahydroxybutiric acids), NEFA (Non Esterified Fatty Acids). Milk yield, open days, rate of insemination per conception, rate of days for first oestrus after parturition were achieved from Dairy Plan herd management systems (Gea Farm Tech/Germany). Serum TG and VLDL levels decreased throughout 2 weeks before parturition in group K (p<0,05; p<0,001 respectively). Serum Chol and LDL concentrations decreased 2 weeks before and the first week after parturition in group Ç. Moreover serum LDL concentration decreased after 2 weeks from parturition in group Ç (P<0,05). Serum HDL levels was not changed between groups throughout study. Serum NEFA level decreased 2 weeks before parturition but then increased at parturition and throughout two weeks after parturition in group Ç (p<0,001; p<0,01; p<0,01; p<0,05 respectively). Serum BHBA concentration decreased from 2 weeks before to 2 weeks after parturition (p<0,001; p<0,01; p<0,01; p<0,01, respectively). Milk yield was similar between groups. Days open, insemination per conception, days from parturition to first heat were mathematically decreased, calving interval was statistically decreased in group Ç as compared group K(p<0,05). As conclusion that orally administration of organic zinc has no affect on milk yield, may improve fatty acid metabolism in liver and reproductive performance, in dairy cows throughout transition period.