The effects of partial replacement of corn silage on biochemical blood parameters in lactating primiparous dairy cows

The aim of this experiment was to investigate the effects of partial replacement of corn silage with long alfalfa hay and/or coarse chopped wheat straw on biochemical parameters in late lactating Holstein primiparous dairy cows. Twelve late lactating Holstein primiparous cows including four cows equipped with a rumen cannula, averaging 210 +/- 20 days in milk and weighing 575 +/- 50 kg were randomly assigned in a 4 x 4 Latin square design. During each of four 21-days periods, cows were fed four total mixed diets that were varied in the forage sources: (1) 50% corn silage (CS), (2) 35% corn silage + 15% wheat straw (CSW), (3) 35% corn silage + 15% alfalfa hay (CSA), (4) 25% corn silage + 10% wheat straw + 15% alfalfa hay (CSWA). At the end of the feeding period, blood samples were taken from jugular vein. Serum glucose, total protein, albumin/globulin, creatinine, creatinin kinase, urea and uric acid levels were determined by using Auto Technicon DAX 72 autoanalyzer. While serum glucose, albumin, globulin, urea, uric acid and creatinine kinase activity were not found significantly different among groups, serum total protein (between CS and CSA, CS and CSWA) and creatinine (between CSA and CSWA) levels had statistical significance at the levels of P < 0.05. It is concluded that rumen propionate and ammonia levels may be good indicator for glucose and BUN, respectively.