Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan.
J Anim Sci. 2012 Dec;90(13):4839-45. doi: 10.2527/jas.2012-5344. Epub 2012 Aug 7.
The effects of feeding and intravenous injections of glucose and VFA on blood ghrelin concentrations were investigated in calves before and after weaning. Eight Holstein bull calves were fed whole milk, allowed free access to solid feeds, and weaned at 7 wk. Measurements were carried out at 2, 4, 6, 9, 11, and 13 wk, at which time jugular blood samples were taken from 4 calves through a catheter from 10 min before to 120 min after their morning feed at 10 min intervals (Exp. 1). An additional 4 calves of the same age were intravenously injected with glucose (1.0 mmol·kg BW(-1)) and a solution of VFA (2.4 mmol·kg BW(-1), acetate:propionate:butyrate in a 6:3:1 ratio) using a catheter, and jugular blood samples were taken temporally relative to the injection time (Exp. 2). In Exp. 1, blood ghrelin concentrations decreased (P < 0.05) after feeding at all ages. However, preprandial ghrelin concentrations were less (P = 0.025) and the degree of postprandial depression of ghrelin tended to be greater during the postweaning period (P = 0.084) than during the preweaning period. Blood glucose concentrations increased after feeding during the preweaning period (P < 0.05), whereas blood acetate concentrations increased during the postweaning period (P < 0.05). In Exp. 2, injection of VFA induced a greater decrease in blood ghrelin concentrations than glucose injection throughout the entire period (P < 0.05). These results indicate that weaning reduces the basal concentration of blood ghrelin because the circulating VFA derived from ruminal fermentation may more strongly depress blood ghrelin concentrations than glucose.
在断奶前后，研究了给犊牛饲喂和静脉注射葡萄糖和 VFA 对血液 ghrelin 浓度的影响。8 头荷斯坦公牛犊牛饲喂全乳，自由采食固体饲料，并在 7 周龄断奶。在 2、4、6、9、11 和 13 周时进行测量，此时通过导管从 4 头犊牛的颈静脉每隔 10 分钟采集一次血液样本，从早晨饲料前 10 分钟到 120 分钟（实验 1）。相同年龄的另外 4 头犊牛通过导管静脉注射葡萄糖（1.0 mmol·kg BW(-1)) 和 VFA 溶液（2.4 mmol·kg BW(-1)，乙酸盐：丙酸盐：丁酸盐的比例为 6:3:1），并在注射时间上采集颈静脉血样（实验 2）。在实验 1 中，所有年龄段在进食后血液 ghrelin 浓度均降低（P < 0.05）。然而，在断奶后时期，餐前 ghrelin 浓度较低（P = 0.025），餐后 ghrelin 浓度的下降程度趋于更大（P = 0.084）。在断奶前时期，进食后血糖浓度升高（P < 0.05），而在断奶后时期，血液乙酸盐浓度升高（P < 0.05）。在实验 2 中，与葡萄糖注射相比，VFA 注射在整个时期都引起血液 ghrelin 浓度更大的降低（P < 0.05）。这些结果表明，断奶会降低血液 ghrelin 的基础浓度，因为来自瘤胃发酵的循环 VFA 可能比葡萄糖更强烈地抑制血液 ghrelin 浓度。
