Rations including high amounts of corn silage are currently very common in dairy production. Diets with corn silage as forage source result in a low supply of essential fatty acids, such as α-linolenic acid, and may lead to low conjugated linoleic acid (CLA) production. The present study investigated the effects of abomasal infusion of essential fatty acids, especially α-linolenic acid, and CLA in dairy cows fed a corn silage-based diet on performance, milk composition, including fatty acid (FA) pattern, and lipid metabolism from late to early lactation. Rumen-cannulated Holstein cows (n = 40) were studied from wk 9 antepartum to wk 9 postpartum and dried off 6 wk before calving. The cows were assigned to 1 of 4 treatment groups. Cows were abomasally supplemented with coconut oil (CTRL, 76 g/d), linseed and safflower oil (EFA, 78 and 4 g/d; linseed/ safflower oil ratio = 19.5:1; n-6/n-3 FA ratio = 1:3), Lutalin (CLA, 38 g/d; BASF SE, Ludwigshafen, Germany; isomers cis-9,trans-11 and trans-10,cis-12 each 10 g/d) or EFA+CLA. Milk composition was analyzed weekly, and blood samples were taken several times before and after parturition to determine plasma concentrations of metabolites related to lipid metabolism. Liver samples were obtained by biopsy on d 63 and 21 antepartum and on d 1, 28, and 63 postpartum to measure triglyceride concentration. Body composition was determined after slaughter. Supplementation of CLA reduced milk fat concentration, increased body fat mass, and improved energy balance (EB) in late and early lactation, but EB was lowest during late lactation in the EFA group. Cows with CLA treatment alone showed an elevated milk citrate concentration in early lactation, whereas EFA+CLA did not reveal higher milk citrate but did have increased acetone. Milk protein was increased in late lactation but was decreased in wk 1 postpartum in CLA and EFA+CLA. Milk urea was reduced by CLA treatment during the whole period. After calving, the increase of nonesterified fatty acids in plasma was less in CLA groups; liver triglycerides were raised lowest at d 28 in CLA groups. Our data confirm an improved metabolic status with CLA but not with exclusive EFA supplementation during early lactation. Increased milk citrate concentration in CLA cows points to reduced de novo FA synthesis in the mammary gland, but milk citrate was less affected in EFA+CLA cows, indicating that EFA supplementation may influence changes in mammary gland FA metabolism achieved by CLA.

Because of their health-promoting properties, flavonoids are used in feed supplements for ruminants, although scientific evidence for their efficacy in vivo is limited. It has been shown recently that bioavailability of quercetin is low after ruminal administration in cows because of degradation by the ruminal microbiota. It is unknown whether quercetin could be absorbed from the small intestine in ruminants if degradation is prevented; therefore, we investigated the bioavailability of quercetin after duodenal administration in 6 German Holstein cows. On 88 ± 3 d in milk, each cow received equivalent doses of quercetin [9, 18, or 27 mg of quercetin equivalents (QE)/kg of body weight] either as quercetin aglycone (QA) or as its glucorhamnoside rutin (RU). In addition, 2 control studies with duodenal administration of NaCl solution (0.9%) were conducted per cow to examine concentrations of flavonoids in plasma during regular feeding. Blood samples were collected at defined time intervals over a period of 24h before and after administration of the test compounds. A washout period of 2d was applied between the runs to avoid possible carryover effects. Concentrations of plasma quercetin aglycone and its metabolites isorhamnetin, tamarixetin, and kaempferol were measured after treatment with glucuronidase/sulfatase by HPLC with fluorescence detection. After administration of RU, levels of plasma quercetin did not increase above baseline, irrespective of dose administered. After duodenal administration of QA, the plasma concentration of QA and its methylated metabolites clearly increased above baseline. The maximal plasma concentrations of total flavonols (about 2h after application) increased in a dose-dependent manner but showed high interindividual variability (range 368.8 to 983.3 nmol/L at 27 mg of QE/kg of body weight) but peak time did not differ. Preadministration baseline values of total flavonols were reached again 3 to 4h after QA administration. The bioavailability of quercetin and its metabolites, as measured by the area under the concentration-time curve, was affected by the quercetin source applied, whereby quercetin from RU was unavailable. Taken together, duodenal administration enhanced bioavailability of QA almost to values previously reported in pigs after oral administration of QA. In contrast to findings in monogastrics or after oral administration in cows, quercetin from RU seems to be unavailable when administered duodenally.

Fatty liver (steatosis) occurs in obese patients, among others, and is related to the development of diabetes type-2. Timely diagnosis of steatosis is therefore of great importance. Steatosis is also the most common liver disease of high-yielding dairy cattle during early lactation. This makes it a suitable animal model for studying liver steatosis. Furthermore, reference of derived ultrasound parameters against a "gold standard" is possible in cattle by taking a liver biopsy for the assessment of fat concentration. The authors undertook this pilot study to investigate the hypothesis that quantitative, computer-aided B-mode ultrasound enables the noninvasive detection of hepatic steatosis. Echographic images were obtained postpartum from dairy cows (n = 12) in transcutaneous and direct (intraoperative) applications using a convex array transducer at 4.2 MHz. During surgery, a biopsy was taken from the caudate lobe to assess the liver fat content (fat score). A custom-designed software package for computer-aided ultrasound diagnosis (CAUS) was developed. After linearizing the post-processing look-up-table (LUT), the image gray levels were transferred into echo levels in decibels relative to the mean echo level in a tissue-mimicking phantom. The quantitative comparison of transcutaneous and intraoperative images enabled the correction for the attenuation effect of skin and subcutaneous fat layer on the mean echo level in the liver, as well as for the effects of the beam formation and attenuation of liver tissue on the echo level vs. depth. The residual attenuation coefficient (dB/cm) in fatty liver vs. normal liver was estimated and compensated for. Finally, echo level was estimated relative to the phantom used for calibration, and echo texture was characterized by the mean axial and lateral speckle size within the regions of interest. In the no fat/low fat group (n = 5) skin plus fat layer attenuation was 3.4 dB/cm. A correlation of skin layer thickness vs. fat score of r = 0.48 was found. The mean transcutaneous liver tissue echo level correlated well with fat score: r = 0.80. A residual liver attenuation coefficient of 0.76 dB/cm and 1.19 dB/cm was found in medium and high fat liver, respectively. In transcutaneous images, correlation of residual attenuation coefficient with fat score was r = 0.69. Axial and lateral speckle sizes were on the order of 0.2 and 1.0 cm, respectively, and no correlation was found with liver fat content. Results for transcutaneous and intraoperative images were similar. The authors conclude that this pilot study shows the feasibility of calibrated, computer-aided ultrasound for noninvasively diagnosing, possibly even screening, steatosis of the liver.

The objective of this study was to test the effects of essential fatty acids (EFA), particularly α-linolenic acid, and conjugated linoleic acid (CLA) supplementation on fatty acid (FA) composition, performance, and systemic and hepatic antioxidative and inflammatory responses in dairy cows. Four cows (126 ± 4 d in milk) were investigated in a 4 × 4 Latin square and were abomasally infused with 1 of the following for 6 wk: (1) coconut oil (control treatment, CTRL; 38.3 g/d; providing saturated FA), (2) linseed and safflower oil (EFA treatment; 39.1 and 1.6 g/d, respectively; providing mainly α-linolenic acid), (3) Lutalin (BASF, Ludwigshafen, Germany; CLA treatment; cis-9,trans-11 and trans-10,cis-12 CLA, 4.6 g/d each), (4) or EFA+CLA. The initial dosage was doubled every 2 wk, resulting in 3 dosages (dosage 1, 2, and 3). Cows were fed a corn silage-based total mixed ration with a high n-6/n-3 FA ratio. Dry matter intake and milk yield were recorded daily, and milk composition was measured weekly. The FA compositions of milk fat and blood plasma were analyzed at wk 0, 2, 4, and 6. The plasma concentration and hepatic mRNA abundance of parameters linked to the antioxidative and inflammatory response were analyzed at wk 0 and 6 of each treatment period. Infused FA increased in blood plasma and milk of the respective treatment groups in a dose-dependent manner. The n-6/n-3 FA ratio in milk fat was higher in CTRL and CLA than in EFA and EFA+CLA. The sum of FA

The aim was to test the accuracy of calibrated digital analysis of ultrasonographic hepatic images for diagnosing fatty liver in dairy cows. Digital analysis was performed by means of a novel method, computer-aided ultrasound diagnosis (CAUS), previously published by the authors. This method implies a set of pre- and postprocessing steps to normalize and correct the transcutaneous ultrasonographic images. Transcutaneous hepatic ultrasonography was performed before surgical correction on 151 German Holstein dairy cows (mean +/- standard error of the means; body weight: 571+/-7 kg; age: 4.9+/-0.2 yr; DIM: 35+/-5) with left-sided abomasal displacement. Concentration of triacylglycerol (TAG) was biochemically determined in liver samples collected via biopsy and values were considered the gold standard to which ultrasound estimates were compared. According to histopathologic examination of biopsies, none of the cows suffered from hepatic disorders other than hepatic lipidosis. Hepatic TAG concentrations ranged from 4.6 to 292.4 mg/g of liver fresh weight (FW). High correlations were found between the hepatic TAG and mean echo level (r=0.59) and residual attenuation (ResAtt; r=0.80) obtained in ultrasonographic imaging. High correlation existed between ResAtt and mean echo level (r=0.76). The 151 studied cows were split randomly into a training set of 76 cows and a test set of 75 cows. Based on the data from the training set, ResAtt was statistically selected by means of stepwise multiple regression analysis for hepatic TAG prediction (R(2)=0.69). Then, using the predicted TAG data of the test set, receiver operating characteristic analysis was performed to summarize the accuracy and predictive potential of the differentiation between various measured hepatic TAG values, based on TAG predicted from the regression formula. The area under the curve values of the receiver operating characteristic based on the regression equation were 0.94 (<50 vs. >or=50mg of TAG/g of FW), 0.83 (<100 vs. >or=100mg of TAG/g of FW), and 0.97 (<50 vs. >or=100mg of TAG/g of FW). The CAUS methodology and software for digitally analyzing liver ultrasonographic images is considered feasible for noninvasive screening of fatty liver in dairy herd health programs. Using the single parameter linear regression equation might be ideal for practical applications.