Chaiyabutr N, Preuksagorn S, Komolvanich S, Chanpongsang S
Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Henri Dunant Road, Patumwan, Bangkok, Thailand.
Comp Biochem Physiol A Mol Integr Physiol. 2000 Jan;125(1):121-30. doi: 10.1016/s1095-6433(99)00167-1.
An experiment was performed to study the glucose kinetics of crossbred Holstein cattle feeding on either hay or 5% urea-treated rice straw during early lactation (30 days post partum), mid-lactation (120 days post partum) and late lactation (210 days post partum). Two breeds: Holstein FriesianxRed Sindhi (50:50 = 50% HF) and Holstein FriesianxRed Sindhi (87.5:12.5 = 87.5% HF) were used. In early lactating 87.5% HF animals feeding on either hay or urea-treated rice straw, the high milk yields and lactose secretion were related to glucose uptake by the udder and udder blood flow as compared with those of 50% HF animals. Marked decreases in udder blood flow, glucose uptake, lactose secretion and milk yield were apparent in mid- and late lactation of both groups of 87.5% HF animals. In contrast, both groups of 50% HF animals showed no significant changes in udder blood flow, udder glucose uptake, lactose secretion and milk yields throughout the course of lactation. Total glucose entry rate using 3-[3H] glucose infusion, recycling of glucose carbon and plasma glucose clearance significantly increased during late lactation for 50 and 87.5% HF animals feeding on urea-treated rice straw. The utilization rates of glucose using [U-(14)C] glucose infusion were not significantly different among groups of animals and periods of lactation. It can be concluded that 87.5% HF animals have the genetic potential for a higher milk yield, but a shorter peak yield and poorer persistence in comparison with 50% HF animals. Changes in the utilization of glucose by the mammary gland for milk production in both groups of crossbred animals during feeding on either hay or urea-treated rice straw would be dependent on intramammary changes.
进行了一项实验，以研究杂交荷斯坦奶牛在泌乳早期（产后30天）、泌乳中期（产后120天）和泌乳后期（产后210天）采食干草或5%尿素处理稻草时的葡萄糖动力学。使用了两个品种：荷斯坦弗里生×红信德（50:50 = 50% HF）和荷斯坦弗里生×红信德（87.5:12.5 = 87.5% HF）。在泌乳早期，采食干草或尿素处理稻草的87.5% HF动物，与50% HF动物相比，高牛奶产量和乳糖分泌与乳腺葡萄糖摄取及乳腺血流量有关。在两组87.5% HF动物的泌乳中期和后期，乳腺血流量、葡萄糖摄取、乳糖分泌和牛奶产量均明显下降。相比之下，两组50% HF动物在整个泌乳过程中，乳腺血流量、乳腺葡萄糖摄取、乳糖分泌和牛奶产量均无显著变化。对于采食尿素处理稻草的50%和87.5% HF动物，在泌乳后期，使用3-[3H]葡萄糖输注的总葡萄糖进入率、葡萄糖碳的再循环和血浆葡萄糖清除率显著增加。使用[U-(14)C]葡萄糖输注的葡萄糖利用率在动物组和泌乳期之间没有显著差异。可以得出结论，与50% HF动物相比，87.5% HF动物具有更高产奶量的遗传潜力，但产奶高峰期较短且持续性较差。两组杂交动物在采食干草或尿素处理稻草期间，乳腺用于产奶的葡萄糖利用变化将取决于乳腺内的变化。
