Short communication: Ca2+-adenosine triphosphatase protein expression in the mammary gland of periparturient cows.

The objectives of this study were to measure the changes in protein expression of the mammary Ca2+-ATPases during the periparturient period and to determine whether Ca2+-ATPase protein expression in the mammary gland is related to milk fever (MF) development. Abundance of Ca2+-ATPase in mammary tissue and milk fat globule membranes was determined by Western blotting. The secretory pathway Ca2+-ATPase was elevated prepartum in mammary tissue from cows that developed MF compared with non-MF cows.

Association between changes in plasma calcium concentration and plasma tartrate-resistant acid phosphatase activity in periparturient cows.

Eight periparturient Holstein Friesian cows were examined for plasma tartrate-resistant acid phosphatase (TRAP) activity to assess the degree of bone metabolic activity and to evaluate the association between the change in calcium (Ca) concentration and bone metabolism during the periparturient period. Milk fever occurred in 1 of 8 cows just after parturition. Plasma TRAP activities did not markedly change in 5 of 8 cows during the experimental period. The changing rate of Ca between preparturition and just after parturition was under -20% in 3 of 8 cows, and low TRAP activities were observed in 2 of these 3 cows. This study suggests that cows with a low TRAP activity are at risk of developing milk fever in comparison to cows with high TRAP activity. Temporary increases of parathyroid hormone were observed in 7 cows, but not in the cow with milk fever.

Reduction in serum lecithin:cholesterol acyltransferase activity prior to the occurrence of ketosis and milk fever in cows.

Lecithin:cholesterol acyltransferase (LCAT) is the enzyme responsible for production of cholesteryl esters in plasma. The LCAT activity is reduced in cows with fatty liver developed during the nonlactating stage and those with the fatty liver-related postparturient diseases such as ketosis. The purpose of the present study was to examine whether reduced LCAT activity during the nonlactating stage could be detected before the occurrence of postparturient diseases. Sera from 24 cows were collected at approximately 10-day intervals from -48 to +14 days from parturition. Of the 24 cows, 14 were apparently healthy, whereas 7 had ketosis and 3 had milk fever at around parturition. Of the 14 healthy cows, 7 had unaltered LCAT activity during the observation period, whereas 7 showed reduced activity from -20 to +14 days. Ketosis and milk fever occurred at from -3 to +10 days, but reductions of LCAT activity in diseased cows had already been observed from days -20 to 0. These results suggest that LCAT activity is virtually unaffected during the peripartum period at least in some healthy cows and also that the reduction in LCAT activity can be detected before the occurrence of ketosis and milk fever.

Studies on the neuromuscular junction with a special preference to nicotinic receptors in normal delivering cows and cows suffering from parturient paresis.

Acetylcholine synthesizing (ACh-s) activity, and binding of 3H-alpha-bungarotoxin (3H-Btx) and 3H-d-tubocurarine (3H-TC) were analysed in gluteus media muscle from normal cows and from cows suffering from parturient paresis, both at parturition and 3 months later. At parturition, the ACh-s activity was 50% lower in the muscle of paretic cows than in non-paretic cows. No difference was found in the number of 3H-Btx and 3H-TC binding sites at parturition, while 3 months after parturition the numbers of 3H-TC and 3H-Btx binding sites were significantly higher in normal than in paretic cows. These significant differences in the number of receptors and a possible underlying receptor regulation defect might be a plausible etiological factor for the disease parturient paresis.

Milk fever in the cow--course of disease in relation to the serum activity of aspartate aminotransferase, alanine aminotransferase, creatine kinase and gamma-glutamyltransferase.

The serum activity of aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), creatine kinase (CK), and gamma-glutamyltransferase (GGT) was determined at the time of first and subsequent treatments in milk fever cows which responded differently to treatment, and in a number of healthy, periparturient cows. Serum ASAT, ALAT and CK levels were lower in the healthy cows than in the milk fever cows at first treatment. Serum ASAT and serum CK were, at first treatment, higher in the milk fever cows which did not recover than in those which recovered. At second and subsequent treatments, serum ASAT and serum ALAT were higher in the cows which failed to recover, and these cows also showed the highest levels of serum CK up-to and including fourth treatment. After an overall assessment of serum activity of the various enzymes, it is concluded that muscle damage was a significant complication both in cows which recovered and in those which failed to recover, while liver damage was of little importance.