A field survey of fat mobilization and liver function of dairy cows during early lactation. Relationship to energy balance, appetite and ketosis
Dale, H.; Vik-Mo, L.; Fjellheim, P.
Nordisk Veterinaermedicin 31(3): 97-105
1979
ISSN/ISBN: 0029-1579 PMID: 432107 Document Number: 145959
Cows were from 35 herds in 3 different districts of Norway with different records of ketosis. Feed intake and milk yield were recorded; each herd was visited 2 to 4 times at intervals of 10 to 20 days during the calving season. From cows in early lactation, up to 90 days after parturition, jugular blood was sampled between 0400 and 0700 h before morning feeding for estimation of acetoacetate and glucose. In blood from cows at another 21 farms non-esterified fatty acid (NEFA), total lipid, bilirubin and glutamic oxaloacetic transaminase (GOT) [aspartate aminotransferase, 2.6.1.1.] were estimated. Daily intake of concentrates was recorded for each cow and roughage consumption was estimated by weighing total feed for at least 10 cows/herd. Energy balance was calculated for each cow as the difference between estimated intake and requirement according to heart girth (maintenance) and fat-corrected milk yield. Results were given in tabular form. Both NEFA and bilirubin were highest at the beginning of lactation after which they gradually decreased. Total lipids were low in early lactation and then rose gradually. Plasma GOT showed no definite trend during the first part of lactation. Acetoacetate was usually low at parturition and the average reached a maximum 21 to 30 days later; glucose showed the inverse pattern. There was a significant negative relation between plasma NEFA and energy balance 3 to 30 days after parturition; r = -0.31, n = 237, P <0.001. Correlation coefficients during the 2nd and 3rd months of lactation were low and not significant. Total lipids, bilirubin and GOT seemed not to depend significantly on energy balance in cows with normal appetite but cows with poor appetite had significantly high bilirubin and GOT. Relations between plasma components were mostly closer in the 1st month of lactation than in the 2nd or 3rd. Cows with ketosis had high NEFA a long time before the signs appeared. Acetoacetate became significantly high only the last days before treatment when plasma glucose was low. Increased mobilization of body fat during the 1st month of lactation seemed to be caused by the negative energy balance that was common in that month.