Relationship between blood urea, protein, creatinine, triglycerides and macro-mineral concentrations with the quality and quantity of milk in dairy Holstein cows

Seventy six high and low producer cows were selected to determine the composition of theblood and milk parameters, and their interrelationships to determine the indices which could beuseful to improve the milk yield. The highest mean blood concentrations were found in highproducer cows. Mean values for blood urea nitrogen (BUN), serum protein (SPtn), creatinine,triglycerides (TGs), cholesterol, and beta-hydroxybutyric acid (BHB) were 25.10 mg dL-1, 10.15 g dL-1,0.81, 62.30, 177.10 and 0.16 mmol L-1, and for macro-minerals including SCa, SMg, serum in-organicphosphorus (SIP), SNa and SK were 3.85, 2.66, 4.63, 108.00 and 4.34 mmol L-1, respectively. Thehighest concentrations for milk parameters, were observed in the high producers, and weresignificant only for MCa, MIP and MMg. Mean values for milk urea nitrogen (MUN), milk protein(MPtn) and lactose were 19.90 mg dL-1, 0.39 g dL-1, and 4.12% and for macro-minerals, 13.24, 3.88,11.03, 73.30 and 16.90 mmol L-1, respectively. There were significant positive correlations betweenthe blood and milk parameters except for creatinine/BHB, TGs/cholesterol and MNa/MK whichwere not significant. The correlations between the blood parameters were greater than in the milkparameters. Creatinine and SPtn, MUN and MPtn were the main parameters in that the relationshipsbetween MPtn with BUN, SPtn and creatinine were more noticeable than others. The regressionanalysis showed that BUN with the SIP and creatinine, MPtn with the BUN and creatinine and MUNwith the SIP and SMg were the appropriate parameters in improvement studies related to the milkyield. In conclusion, BUN, SPtn, MUN and MPtn concentrations are the most effective indices forpredicting the preferred milk yield.