The objective of this study was to evaluate the association between ketonemia and serum paraoxonase-1 (PON1), malondialdehyde (MDA), and other blood components in tail and mammary veins of dairy cows. Forty-two Holstein dairy cows with decreased feed intake were divided into HIGH (≥ 1.2 mM; n = 31) and LOW (< 1.2 mM; n = 11) groups based on the β-hydroxybutyrate concentration in plasma collected from the tail vein. The HIGH group had a significantly greater plasma non-esterified fatty acid (NEFA) concentration, but significantly lower serum PON1 activity and phospholipid concentration, and a tendency to have a lower cholesterol ester concentration than the LOW group. Serum PON1 activity was not correlated with the MDA concentration but was positively correlated with serum concentrations of cholesterol esters and phospholipids, and negatively correlated with the plasma NEFA concentration. These results suggest that serum PON1 activity is reduced by hyperketonemia and the relevance of PON1 to MDA seems to not be direct, though it is involved.

Subclinical ketosis (SCK) is defined as elevated concentrations of circulating ketone bodies in the absence of clinical signs. Measurement of blood β-hydroxy butyric acid (BHBA) concentration is considered as the gold standard method to detect SCK. The objective of this study was to determine the presence of SCK in cows in different physiologic status in Basra, Iraq. The cows were classified into 5 groups according to the physiologic group; G1: 2nd trimester pregnant cows (n =9), G2: 3rd trimester pregnant cows (n =8), G3 Fresh cows (1-30 days postpartum) (n=41), G4: Lactating cows (2 and 3 months postpartum) (n =21), and G5: 4 months – more postpartum cows (n =14) . Cholesterol, ALT activity and BHBA concentrations were determined. The cutoff point 1000 μmol L-1 -2600 μmol L-1 was used. The mean concentrations of the parameters of the cows of the five groups were; cholesterol: 3.7 ± 0.34, 3.21 ± 0.38, 2.59 ± 0.16, 3.15 ± 0.24 and 2.5 ± 0.28 mmol/L, ALT: 45.11 ± 6.16, 37.125 ± 3.98, 44.83 ± 3.36, 45.19 ± 4.57 and 41.29 ± 4.37 IU/L and BHBA: 2.014 ± 0.15, 2.086 ± 0.085, 1.94 ± 0.07, 1.89 ± 0.18 and 1.92 ± 0.075 mmol/L. The concentration of cholesterol was within the normal limits in the all groups but it showed descending trend from early pregnancy to parturition then elevated with advancement of lactation, while the activity of ALT showed highness in each group with different percent, whereas the concentration of BHBA was significantly high in the all groups. The present findings reveals that prevalence of subclinical ketosis in Basra is extremely high. To prevent the consequences of subclinical ketosis, feeding a good feed stuff with propylene glycol and implementing a good management with regular test for detecting SCK to reduce the economic losses caused by SCK.

Objective-To use threshold concentrations of acetone and beta-hydroxybutyrate in milk and serum, respectively; identify risk for ketosis and endometritis; and assess analyses of blood and milk samples as predictors of risk for ketosis in high-yielding dairy cows. Animals-90 multiparous Holstein cows. Procedure-At intervals before and after parturition, blood samples were obtained for determination of glucose, nonesterified fatty acids, leptin, insulin, insulin-like growth factor-1, and beta-hydroxybutyrate concentrations. Samples of milk were obtained at similar intervals after parturition for determination of fat content and concentrations of acetone, protein, and lactose. Reproductive examination of each cow was performed weekly. Results-For each cow, threshold concentrations of acetone and β-hydroxybutyrate were calculated as 75th and 90th percentiles of maximum postpartum concentrations of acetone in milk (0.40 and 0.87 mmol/L) and β-hydroxybutyrate in serum (2.30 and 3.51 mmol/L). Significant decrease in milk production (442 to 654 kg of energy-corrected milk/305-day period per cow) was associated with acetone or beta-hydroxybutyrate in excess of threshold values. Milk acetone concentrations > 0.40 mmol/L were associated with 3.2 times higher risk for endometritis. Low plasma glucose, high serum beta-hydroxybutyrate, and high milk acetone concentrations during week 1 after parturition were indicators of increased risk for ketosis later during lactation. Conclusions and Clinical Relevance-Determination of milk acetone concentration during the week after parturition may identify cows at risk for ketosis and endometritis; with appropriate interventions, development of disease and production losses may be reduced.

Metabolic and production responses are reported for 72 cows treated with bovine somatotropin (BST) for 30 days starting at day 70 of lactation. Of these 72 cows, 48 had been exposed in the preceding lactation to long-term treatment with BST at 3 dosages and 24 (controls) had not been given BST. Approximately half of the cows in each group were parity-2 cows, the rest were older. Comparisons between groups were made separately for parity-2, and older cows. Analyses, using pretreatment values of each variable as a covariate, indicated that older cows, but not parity-2 cows, significantly (P < 0.05) increased milk production during treatment. Parity-2 cows, however, had a significantly higher milk fat percentage than controls following treatment. Cows treated with 51.6 or 86 mg BST/d in both parity groups has significantly higher serum-free fatty acids than controls. Estimated net energy balances were significantly lower for older treated cows, but did not significantly differ from controls from for parity-2 treated cows. Older cows in the 86 mg of BST/d group tended to have higher concentrations of blood glucose than did older control-group cows. Treatment with BST did not significantly increase serum ketone concentrations in any group of animals, and none of the cows developed clinical ketosis during this period. Estimated net energy balance (ENEB) during treatment was a significant (P < 0.05) covariate for free fatty acid concentrations in older cows and for milk fat percentage in parity-2 cows. Covariate adjusted analyses, using ENEB during treatment as a covariate, indicated that lipolytic stimuli already acting may be enhanced by treatment with BST, but a negative energy balance was not a necessary precondition for free fatty acid concentrations to increase following somatotropin treatment. Similarly, milk fat percentages for parity-2 treated cows were significantly (P < 0.05) higher during treatment than controls when ENEB during treatment was used as a covariate. Increased milk fat concentrations in parity-2 treated cows were not associated with significant increases in the ratio of C(18):C(4-10) milk fatty acids, indicating that increased milk fat resulted from either an increase in incorporation of C(18) fatty acids into milk fat coupled with an increase in de novo mammary synthesis of C(4-10) milk fatty acids or an increase in C(12-16) fatty acids that may arise either from increased tissue mobilization, from diet, or from de novo mammary synthesis.