Relationship Between Urine PH And Production Performance And Health In Lactating Dairy Cows

There is an effective mechanism regulating acid-base balance in dairy cows, which maintains a stable range of pH in vivo. Once the acid-base balance disorders occur, the pH would exceed the normal range. The acid-base balance disorder in dairy cows is closely related to health and disease, which seriously affects the production performance in dairy cows. Urine pH is the most intuitive external manifestations of acid-base balance in dairy cows. However, there is fully unclear relationship between urine and mineral metabolism, energy metabolism, liver function, renal function, inflammation and blood-gas. The objective of this study is to reveal relationship of urine pH with production and health in lactating cows, and to provide scientific basis for monitoring effectively acid-base balance disorder and health in dairy cows in future.To understand changes and effects of urine p H in lactating cows, 601 urine samples of 257 lactating cows were collected in an intensive dairy farm in the west of Heilongjiang Province, 57 of these cows were selected to do the experiment, which were assigned to acid group(24 cows), neutral group(22 cows) and partial alkali group(11 cows) according to the urine pH. The acid group was further assigned into polar acid group(15 cows) and partial acid group(9 cows). Milk yield, disease status and the culled rate of the test cows were tracked. Results showed that:(1) Milk yield of the polar acid group was significantly lower than that of the neutral group(p<0.01), the partial acid group and the partial alkali group(p<0.05). BCS of the polar acid group and the partial acid group was very significantly lower than the neutral group(p<0.01), while BCS of the partial alkali group was obviously higher than the polar acid group(p<0.01) and the partial acid group(p<0.05).(2) Incidence of disease in the acid group and the partial alkali group was 83.33% and 72.72% respectively, which was higher than 18.18% in the neutral group. Forestomach atony/Ruminal tympany had a higher incidence of 33.33% in the acid group, and mastitis was 36.36% in the partial alkali group. There was a strong and negative association of acid urine with ruminal acidosis, displacement of the abomasum, forestomach atony, ketosis and laminitis and a strong and positive correlation between partial alkali urine and mastitis.(3) In the culled rate, the polar acid group, the partial acid group, the neutral group, and the partial alkali group was in turn 26%, 0, 5%, and 18%.To reveal changes of clinical pathology for blood and urine in dairy cow with different urine pH, dairy cows from the aboved experiment were selected to measure 7 mineral elements, 7 inflammatory indexes, 9 energy metabolism indicators, 12 hepatic function indexes and 13 blood gas analysis indexes in blood or urine. Results showed that:(1) Mineral elements in the acid group, compared with the neutral group, serum K and serum Cu level in the polar acid group were very significantly lower than the neutral group(p<0.01), serum Mg and urine Mg in the polar acid group were lower(p<0.05), urine Ca in the polar acid group was significantly higher(p<0.05), while urine Ca in the partial acid group and urine P in the polar acid group were much significantly higher than the neutral group(p<0.01), serum Fe level in the partial acid group was significantly lower than the neutral group(p<0.05).(2) Inflammatory factors in the polar acid group serum LPS level was significantly higher(p<0.05), serum SAA in the partial acid group was significantly lower(p<0.05), compared with the neutral group; serum HP in the partial alkali group was much significantly higher(p<0.01) and serum HIS in the partial alkali group was significantly lower(p<0.05), compared with the neutral group.(3) In energy metabolism, serum BHBA level in the polar acid group was lower than the partial acid group, both of them were higher than the neutral group and the partial alkali group(p<0.05 or p<0.01), serum L-ACT in the polar acid group was significantly higher than the partial acid group and the partial alkali group(p<0.05), serum GLU in the polar acid group and the partial acid group was obviously lower than the neutral group and the partial alkali group(p<0.01), serum NEFA in the acid group was higher than the neutral group and the partial alkali group(p<0.05).(4) In renal function, Urine BUN level in the polar acid group was much significantly higher than the neutral group and the partial alkali group(p<0.01), urine Cr in the neutral group was obviously higher than the partial acid group and the partial alkali group(p<0.05).(5) In blood gas analysis, blood K+ concentration in the acid group was obviously lower than the neutral group, while HCO3-, TCO2, BEb and BEecf in blood were very significantly higher than the neutral group(p<0.01).(6) In hepatic function, serum GLO in the neutral group was obviously lower than the acid group and the partial alkali group(p<0.05), serum A/G in the neutral group was higher than the partial alkali group(p<0.05), serum CK in the acid group was higher than the neutral group(p<0.01),serum AST in the acid group was higher than the partial alkali group(p<0.01).Conclusion obtained that abnormal urine pH of the lactating cows in the test farm was usually acidic, it might give rise to a decrease of milk yield and a increased incidence of diseases and the culled, etc. The experiment clarified that the lactating cows with the abnormal urine pH(in particular acid urine) may have acid-base balance disorders, and accompanied by ketosis, rumen acidosis, inflammation, abnormal hepatic function, abnormal renal function, mineral elements mebabolic disturbance, etc.