不同饲粮模式对奶牛乳腺长链脂肪酸摄取的影响

本试验旨在研究不同饲粮模式对奶牛乳腺长链脂肪酸摄取的影响。选用健康且胎次、体重[(554±21)kg]、泌乳期[(120±4)d]和产奶量[(24.30±1.47)kg/d]相近的荷斯坦奶牛30头,采用随机区组设计,分为3组,每组10头。3组奶牛饲喂不同模式的饲粮,即以苜蓿、羊草和全株玉米青贮为粗饲料的饲粮(MF组)、营养水平约同MF组但以单一玉米秸秆为粗饲料的饲粮(CS1组)和粗饲料比例等同MF组但以单一玉米秸秆为粗饲料的饲粮(CS2组)。试验期90 d,分3期进行,每期30 d,在每期的最后2 d采集饲粮样、乳样和血样进行检测分析。结果表明:1)不同饲粮模式对奶牛的体重和干物质采食量均无显著影响(P0.05),但对奶牛的产奶量、乳脂率和日乳脂产量均有显著影响(P0.05)。MF组的产奶量和日乳脂产量均显著高于CS1组和CS2组(P0.05),而CS1组则显著高于CS2组(P0.05);MF组的乳脂率显著高于CS1组(P0.05)。2)不同饲粮模式对奶牛动、静脉血浆中C16∶0、C18∶0、C18∶2cis-6、C18∶1 cis-9和总长链脂肪酸的浓度均无显著影响(P0.05)。3)不同饲粮模式对奶牛的血流量造成了显著的影响(P0.05),呈现出CS1组MF组CS2组。不同饲粮模式影响了奶牛动脉对总长链脂肪酸的供给量,表现为MF组和CS1组显著大于CS2组(5 629.51、6 605.02 g/d vs.3 878.91 g/d)(P0.05)。4)不同饲粮模式影响了奶牛乳腺对总长链脂肪酸的摄取率,表现为MF组和CS2组显著高于CS1组(10.99%、10.84%vs.7.39%)(P0.05)。5)不同饲粮模式影响了奶牛乳腺对总长链脂肪酸的摄取量,表现为MF组(618.69 g/d)CS1组(487.87 g/d)CS2组(420.56 g/d),组间差异显著(P0.05)。本研究揭示了在低质粗饲料条件下,增加精料浓度并不能有效提高奶牛乳腺对长链脂肪酸的摄取。

Effects of Different Dietary Patterns on Mammary Uptake of Long Chain Fatty Acids for Dairy Cows

This experiment was conducted to investigate the effects of different dietary patterns on mammary uptake of long chain fatty acids for dairy cows. Thirty healthy Holstein cows with the similar parity, body weight [(554±21)] kg, lactation period [(120±24) d] and milk yield [(24.30±1.47) kg/d] were ran-domly assigned to 3 groups with ten cows each using a randomized block design. Dairy cows in 3 group were fed different pattern diets: one diet' s roughage consisted of alfalfa, Leymus chinensis and whole corn silage ( MF group) , one diet' s roughage consisted of only corn straw and containing similar nutrient level with MF group ( CS1 group) , and the last one diet' s roughage consisted of only corn straw and containing equal rough-age ratio with MF treatment ( CS2 group) . The experiment lasted for 90 days with 3 periods, and each period had 30 days. Diet, milk and blood samples were collected and examined at last 2 days of each period. The re-sult showed as follows:1) different dietary patterns had no significant effects on body weight and dry matter intake ( P>0.05) , but had significant effects on milk yield, milk fat percent and daily milk fat yield for dairy cows ( P<0.05) . The milk yield and daily milk fat yield in MF group were significantly higher than those in CS1 and CS2 groups ( P<0.05) , and above indices in CS1 group were significantly higher than those in CS2 group ( P<0.05); the milk fat percent in MF group was significantly higher than that in CS1 group ( P<0.05) . 2) Different dietary patterns had no significant effects on the concentrations of C16:0, C18:0, C18:2cis-6, C18:1cis-9 and total long chain fatty acids in artery and vein plasma for dairy cows (P>0.05). 3) Different dietary patterns had no significant effect on mammary blood flow (P<0.05), and it showed CS1 group>MF group>CS2 group. Artery supply of total long chain fatty acids was affected by different dietary patterns, which showed MF and CS1 groups was significantly bigger than CS2 group ( 5629. 51 and 6605. 02 g/d vs. 3878.91 g/d) ( P<0.05) . 4) Mammary extraction rate of total long chain fatty acids was affected by different dietary patterns, which showed MF and CS2 groups was significantly bigger than CS1 group ( 10. 99% and 10.84% vs. 7.39%) ( P<0.05) . 5) Mammary uptake of total long chain fatty acids was affected by different dietary patterns, which showed MF group ( 618. 69 g/d ) > CS1 group ( 487. 87 g/d ) > CS2 group (420.56 g/d), and the difference was significant among groups (P<0.05). This study reveales that in the condition of low quality roughage diets, it is not an effective way to improve the mammary uptake of long chain fatty acids by simply increasing the proportion of concentration.