Plasma Concentration and Lipid Composition of Lipoproteins in Lactating Dairy Cows Fed Control and High Grain Diets

Six multiparous Holstein cows ranging from 7 to 19 wk postpartum were in a switchback design to determine effects of feeding high grain diets on lipoprotein concentration and composition in blood. Percents concentrate, alfalfa haylage, and corn silage of control and high grain diets were 50, 83; 25, 9; and 25, 8 dry matter. Milk yield (kg/day), milk fat percentage, and fat yield (g/day) averaged 27.7, 3.58, 997 and 30.2, 2.45, 729 for control and high grain treatments. Very low density, low density, and high density lipoproteins were isolated by gel filtration of total lipoproteins obtained by ultracentrifugation. Lipoprotein concentrations in blood plasma of cows fed the control or high grain diets were similar. Triglyceride, phospholipid, cholesterol, and cholesterol ester contents of each lipoprotein class were not altered by treatment. High grain feeding increased octadecadienoic fatty acid content of low density and high density lipoprotein cholesterol esters and decreased octadecenoic and octadecatrienoic acids. The trend was similar for the very low density lipoprotein fraction. Phospholipid octadecenoic acid decreased in all lipoprotein fractions but only significantly for high density lipoproteins. It is unlikely that differences in lipid composition of plasma lipoproteins caused alterations in lipoprotein metabolism leading to fat depression in this and other similar studies.     

Feeding hydrogenated fatty acids and triglycerides to lactating dairy cows

Effects of feeding hydrogenated tallow fatty acids and triglycerides to lactating dairy cows were studied using five primiparous Holstein cows in a 5 x 5 Latin square design. A control diet with no supplemental fat and diets containing either hydrogenated tallow fatty acids or triglycerides at 2 and 5% levels were fed for ad libitum intake. Diets were isonitrogenous but not isocaloric. Each treatment period consisted of 28 d; the last 14 d were used for data collection. Fat-supplemented diets had no effects on DM intake, milk fat percentage, milk protein percentage, and BW compared with the control diet. Energy intake and milk yields were higher for cows fed fat-supplemented diets. Adding fatty acids to diets increased milk fat percentage above that in milk from cows fed triglyceride diets. Apparent digestibilities of DM and OM were lowered by the addition of fat, mainly in response to fatty acid additions. Feeding fatty acids reduced ash digestibility compared with feeding triglycerides, and NDF digestibility also tended to be lower for cows fed fatty acid diets. Fat addition to diets reduced fatty acid digestibility; digestibility of added fat averaged 37.7%. Although of similar saturation, the triglyceride supplement was more ruminally inert than the fatty acid supplement. Esterification and degree of saturation are features of importance when processing tallow for use in ruminant diets.     

EFFECT OF DIETARY MILK CREAM AND EGG YOLK FAT ON SERUM AND LIVER LIPID PROFILE IN RATS

Influence of dietary fat from milk and egg yolk on serum and liver lipid profile was studied in rats. Rats fed milk fat at 5% level for 8 weeks showed a 17% decrease in serum cholesterol and 31% decrease in triacylglycerol compared to the control group of rats fed groundnut oil (GNO). Liver cholesterol was decreased by 20% in the milk fed group. There was no difference in serum cholesterol concentration of rats fed egg yolk compared to the control animals. However, triacylglycerol and phospholipids in serum of rats fed egg yolk were decreased by 20 and 24%, respectively. In another set of experiments animals were rendered hypercholesterolemic by feeding a diet containing 0.5% cholesterol. Addition of milk fat in the diet decreased serum and liver cholesterol by 11 and 17%, respectively, compared to rats fed on a control diet. Similarly, triacylglycerols were decreased by 23 and 8%, respectively, in serum and liver of animals given     

A kinetic concepto of lipid transport in ruminants.

Summarization of the literature shows a strong correlation between dietary fatty acid intake and total lipid concentration in plasma in lactating cows whereas total milk fat secreted is related to neither of these. In the process of plasma triglyceride removal, chylomicra and very low density lipoproteins are converted to low density lipoproteins. Limited kinetic data indicate that the fractional removal rates for chulomicra and very low density lipoproteins are rapid in lactating cows whereas fractional removal of low density lipoproteins is slower, resulting in accumulation of the latter in plasma. Under such conditions, low density lipoprotein concentrations of plasma would not be expected to reflect quantitatively the transfer of plasma triglyceride fatty acids to milk fat. Quantitative analysis or triglyceride fatty acid turnover in density less than 1.006 lipoproteins should delineate the role of plasma lipid transport in milk fat synthesis. High fat diets protected from rumen biohydrogenation have proven to be a useful approach in studying ruminant fat metabolism and may be used more extensively to elucidate the role of cholesterol in plasma lipid transport and the metabolism of essential fatty acids in ruminants.     

茯砖茶奶茶对高脂小鼠血脂水平的影响

为探究茯砖茶奶茶对高脂饲料喂养小鼠血脂水平的影响。本实验选取126只雄性昆明小鼠,根据体重随机分成7组,即空白组、对照组、茶汤组、牛奶组、低剂量奶茶组(167 mg/kg)、中剂量奶茶组(834 mg/kg)、高剂量奶茶组(1667mg/kg);通过对小鼠饲喂高脂饲料建立高脂模型,连续喂养28 d、35 d、42 d分析茯砖茶奶茶对高脂小鼠甘油三酯(TG)、总胆固醇(TC)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)四项指标的影响。结果表明:灌胃低、中、高剂量的茯砖茶奶茶与对照组相比,中剂量奶茶组能显著降低高脂小鼠的TC、TG、LDL-C含量(p0.05),各指标下降比率分别为16.38%、66.67%、34.34%。在连续灌胃28 d、35 d、42 d,其中茶汤组在35 d时降脂效果显著,牛奶组无显著性差异变化,中剂量茯砖茶奶茶灌胃高脂小鼠在28 d时血脂呈最低水平。综上,茯砖茶奶茶具有显著降低血脂的作用,为进一步开发以茯砖茶为原料的产品提供了理论依据。     

Effects of feeding lactating dairy cows diets containing whole soybeans and tallow.

Four multiparous Holstein cows averaging 133 d postpartum and fitted with ruminal cannulas were utilized in a 4 x 4 Latin square design to investigate the effects of feeding diets containing whole soybeans and tallow. Treatments were 1) control, no added fat; 2) control and 10% whole raw soybeans; 3) control, 10% whole raw soybeans, and 2.5% tallow; and 4) control, 10% whole raw soybeans, and 4.0% tallow. Cows were fed for ad libitum intake a diet of alfalfa haylage, corn silage, and concentrate (45:5:50, DM basis). Intakes of DM and production of milk, milk CP, milk SNF, and 4% FCM were not affected by feeding supplemental fat. Production of milk fat and weight percentages and yields of long-chain fatty acids in milk fat were increased, whereas weight percentages and yields of short- and medium-chain fatty acids were decreased by feeding supplemental fat. Digestibilities of DM, OM, energy, cellulose, and fatty acids were decreased slightly when fat was added to the diet, but utilization of energy and N for production of milk was not altered. Supplemental fats increased concentrations of NEFA and cholesterol in plasma. These data indicate that relatively large amounts of unprotected fat can be added to the diet of lactating dairy cows without deleterious effects on milk composition, ruminal fermentation, or nutrient digestibilities.     

Dietary Intake of Structured Lipids with Different Contents of Medium‐Chain Fatty Acids on Obesity Prevention in C57BL/6J Mice

Three medium‐ and long‐chain triacylglycerols (MLCT) with different contents of medium‐chain fatty acids (MCFA) (10% to 30%, w/w) were prepared and evaluated for their anti‐obesity potential in C57BL/6J mice. The group fed with a high fat diet of MLCT containing 30% (w/w) MCFA showed significantly decreased body weight and fat mass (P < 0.05) relative to the control mice fed an obesity‐inducing high fat rapeseed oil diet. In addition, serum parameters including triacylglycerols, total cholesterol, glucose, high‐density lipoprotein cholesterol, low‐density lipoprotein cholesterol, apolipoprotein A1 and apolipoprotein B in the treatment group fed with 30% (w/w) MCFA were close to those of mice fed with a low fat rapeseed oil diet, but significantly different (P < 0.05) from those of the obesity control group. Moreover, the intake of MLCT with high content of MCFA reduced the size of adipocytes. In addition, the visceral fat and liver weights, as well as the liver triacylglycerol for 3 treatment groups were lower than those of the obesity control group. These results demonstrate the great potential of MLCT with high content of MCFA in weight loss.     

Trans18:1 and 18:2 isomers in blood plasma and milk fat of grazing cows fed a grain supplement containing solvent-extracted or mechanically extracted soybean meal

Thirty Holstein cows grazing mixed clover-grass pastures for 12 wk from May through July were fed a grain supplement containing solvent-extracted soybean meal (SES), or mechanically extracted soybean meal (MES) to determine whether differences in supplemental 18:2n6 fatty acid intake altered secretion of unsaturated fatty acids. Groups of 10 cows each were fed in two equal feedings a supplement (7.3 kg/d) containing ground corn plus either 1.8 kg of SES, 2.2 kg of MES, or 2.2 kg of MES plus 30 g of methionine hydroxy analog (Alimet; MESM). Fatty acid content (% of DM) of grass and clover in pastures averaged 1.9 and 1.5%, respectively. Concentration of 18:3n3 was higher in grass compared with clover (532 vs. 454 mg/g of total fatty acids). Yield of milk (32 kg/d average) and milk components did not differ by supplements. Total blood plasma fatty acids (mg/ml) during wk 4 were higher due to MESM (1.0) compared with MES (0.6) or SES (0.6). Cows fed MESM or MES had greater concentrations of 18:2n6, trans11-18:1, and cis9,trans11-18:2 in plasma compared with cows fed SES. The additional trans11-18:1 was found exclusively in plasma triglycerides, whereas the additional cis9,trans11-18:2 was found in plasma phospholipids and free fatty acids. Daily yields of 18:2n6, trans11-18:1 and cis9,trans11-18:2 in milk fat were greater for cows fed MES or MESM compared with SES. Results indicate yields of trans11-18:1, cis9, trans11-18:2, 18:2n6, and 18:3n3 in milk fat of pasture-fed cows were enhanced by feeding a grain supplement containing mechanically extracted, rather than solvent-extracted, soybean meal.     

Lactational response of cows fed condensed corn distillers solubles

Fifteen Holstein cows (6 multiparous and 9 primiparous) in early lactation were used in a replicated 3 × 3 Latin square design with 5-wk periods to evaluate the use of condensed corn distillers solubles (CCDS) in the total mixed ration. Diets were control (0%), low (5%), or high (10% of dry matter) CCDS. All diets contained alfalfa hay, corn silage, rolled corn, and a concentrate supplement formulated to yield isonitrogenous diets. Condensed corn distillers solubles replaced a portion of the rolled corn and soybean meal in the control diet. Data were collected from wk 3 to 5 of each 5-wk period. Dry matter intakes (23.4, 24.4, and 22.5 kg/d for control, low, and high CCDS, respectively) were similar for CCDS and control and tended to be greater for low than for high CCDS. Milk yields (34.1, 35.5, and 35.8 kg/d) were greater for added CCDS vs. control, with no additional benefit found by feeding a high over a low amount of CCDS. Milk fat percentage decreased slightly, whereas protein and lactose production increased when cows were fed CCDS. Medium-chain fatty acids in milk fat were decreased and long-chain fatty acids increased by feeding CCDS, and similar changes were found comparing high with low level of CCDS. Unsaturated fatty acids in milk fat tended to be higher for diets containing CCDS compared with control and were higher for high compared with low inclusion. Ruminal ammonia and serum urea nitrogen concentrations were lower when cows were fed CCDS. This study indicated that it is advantageous to feed CCDS at 5% of dry matter; however, some beneficial changes in milk fatty acid composition were achieved by doubling that amount.     

Effects of feeding diets containing calcium salts of long-chain fatty acids to lactating dairy cows.

Four cows were utilized in a 4 x 4 Latin square design to investigate the effects of feeding Ca salts of long-chain fatty acids. Treatments were control diet with 1) no added fat, 2) 3% Ca salts of long-chain fatty acids, 3) 6% Ca salts of long-chain fatty acids, and 4) 9% Ca salts of long-chain fatty acids. Cows were fed chopped alfalfa hay, alfalfa haylage, corn silage, and concentrate (15:22:13:50) on a DM basis. Dry matter intake, energy intake, and ruminal fermentation were not altered greatly until Ca salts of long-chain fatty acids constituted 9% of DMI. Digestibilities of DM, OM, ADF, NDF, and hemicellulose were not affected by treatment. Digestibilities of cellulose, soluble residue, total C18 fatty acids, and total fatty acids followed quadratic patterns. Absorption of N was increased linearly when fat was fed, but digestibility of Ca was decreased linearly. Milk production, CP, and SNF were not altered greatly by inclusion of 3 or 6% Ca salts of long-chain fatty acids in the diet, but inclusion of 9% Ca salts of long-chain fatty acids decreased their production. Calcium salts of long-chain fatty acids increased milk fat percentage and production of fat and FCM when fed as 3 or 6% of the dietary DM but decreased yields of milk fat and FCM when fed as 9%. Calcium salts of fatty acids can be fed to provide up to 6% of the dietary DM without deleterious effects on ruminal fermentation and digestibilities of most nutrients.