DISCIZIA, Faculty of Veterinary Medicine, Federico II University, Naples, Italy.
Anim Reprod Sci. 2010 Oct;122(1-2):74-81. doi: 10.1016/j.anireprosci.2010.07.005. Epub 2010 Jul 27.
The aim was to establish the capacity of buffalo heifers to adapt their metabolic requirements to a low energy diet. Murrah buffalo (Bubalus bubalis) heifers undergoing regular estrous cycles were randomly assigned by age, live weight (LW) and body condition score (BCS) to a high energy group (HE, 5.8 milk forage units (MFU)/day, n=6) or low energy group (LE, 3.6 MFU/day, n=6). Circulating concentrations of metabolic substrates, metabolic hormones and reproductive hormones were determined weekly for 19 weeks. Ovarian follicular characteristics and oocyte parameters were also ascertained weekly. Heifers fed the LE diet had a better dry matter conversion than heifers fed the HE diet and the calculated daily energy provision was negative for heifers fed the LE diet (-0.248 MFU) and positive for heifers fed the HE diet (5.4 MFU). Heifers fed the HE diet had an increase in 50 kg LW over the duration of the study whereas LW remained constant for heifers fed the LE diet. The BCS of heifers fed the HE diet (4.2) was greater (P<0.05) than the BCS for heifers fed the LE diet (3.4). Heifers fed the HE diet had greater (P<0.05) circulating concentrations of metabolic substrates (glucose, total cholesterol and HDL cholesterol) and metabolic hormones (insulin, glucagon, leptin and T3) compared with heifers fed the LE diet. There were no significant differences in circulating reproductive hormones between the two groups of heifers. Ovarian follicular characteristics were similar for the two groups of heifers while heifers fed the LE diet tended to have oocytes of reduced quality compared with heifers fed the HE diet. The most notable finding was that heifers fed the LE diet had a negative calculated daily energy provision but were able to maintain LW and reproductive activity. It was concluded that buffalo heifers may potentially have the capacity to undergo metabolic adjustment and reduce their energy requirements when dietary energy is limiting. This adaptive capacity would explain why buffaloes remain productive in environments that are limiting to other ruminants.
本研究旨在确定水牛小母牛适应低能量饮食的代谢需求的能力。处于正常发情周期的摩拉水牛小母牛（Bubalus bubalis）根据年龄、活重（LW）和体况评分（BCS）随机分为高能量组（HE，5.8 奶草料单位/天，n=6）或低能量组（LE，3.6 MFU/天，n=6）。在 19 周内每周测定代谢底物、代谢激素和生殖激素的循环浓度。还每周确定卵巢卵泡特征和卵母细胞参数。与饲喂 LE 日粮的小母牛相比，饲喂 LE 日粮的小母牛具有更好的干物质转化效率，并且饲喂 LE 日粮的小母牛的计算日能量供应为负值（-0.248 MFU），而饲喂 HE 日粮的小母牛的计算日能量供应为正值（5.4 MFU）。在研究期间，饲喂 HE 日粮的小母牛的 50 kg LW 增加，而饲喂 LE 日粮的小母牛的 LW 保持不变。饲喂 HE 日粮的小母牛的 BCS（4.2）大于（P<0.05）饲喂 LE 日粮的小母牛的 BCS（3.4）。与饲喂 LE 日粮的小母牛相比，饲喂 HE 日粮的小母牛具有更高的（P<0.05）循环代谢底物（葡萄糖、总胆固醇和 HDL 胆固醇）和代谢激素（胰岛素、胰高血糖素、瘦素和 T3）浓度。两组小母牛之间的循环生殖激素无显著差异。两组小母牛的卵巢卵泡特征相似，而饲喂 LE 日粮的小母牛的卵母细胞质量往往低于饲喂 HE 日粮的小母牛。最值得注意的发现是，饲喂 LE 日粮的小母牛的计算日能量供应为负值，但能够维持 LW 和生殖活动。结论是，水牛小母牛可能具有在日粮能量有限时进行代谢调整和降低能量需求的潜力。这种适应能力可以解释为什么水牛在限制其他反刍动物的环境中仍能保持生产力。
