Phlorizin induces lipolysis and alters meal patterns in both early- and late-lactation dairy cows
Phlorizin induces lipolysis and alters meal patterns in both early- and late-lactation dairy cows
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DOI：
10.3168/jds.2006-631
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发表时间：
2007-04-01
影响因子：
3.5
通讯作者：
Allen, M. S.
中科院分区：
文献类型：
--
作者：
Bradford, B. J.;Allen, M. S.
在过去的反刍动物研究中，邻苯二甲酸乙酯能增加全身葡萄糖需求，但也能刺激脂肪分解。增加的脂肪分解通过向肝脏提供额外的氧化底物而使肝氧化对干物质摄入（DMI）调节的研究复杂化。因此，为了评估葡萄糖需求的增加是否会选择性地增加负能量平衡奶牛的DMI，在泌乳早期和后期的奶牛中施用了草霉素。选取6头泌乳早期荷斯坦奶牛（19 +/- 6 DIM，产奶量50.0 +/- 1.8 kg/d，平均+/- SD）和6头泌乳后期荷斯坦奶牛（228 +/- 18 DIM，产奶量30.6 +/- 1.9 kg/d），采用交叉设计随机分组。试验期为14 d，其中适应期7 d，处理期7 d。在整个治疗期间，每6小时皮下注射一次苯丙嗪（4 g/d）和丙二醇（载体和对照）。在每个治疗期的最后4 d采集摄食行为和DMI数据；在每个治疗期的第4天采集血样和总尿量。在泌乳初期和泌乳后期，苯酞素分别造成333 g/d和532 g/d的尿糖损失。在泌乳早期和泌乳后期奶牛中，邻苯二嗪增加血浆非酯化脂肪酸浓度相似，但不显著改变血浆胰岛素浓度。用苯并菌素处理有减小饲料粒度的趋势，但也能缩短间隔期，对DMI没有影响。根霉素对脂肪分解、摄食行为和DMI的影响不依赖于相对能量平衡。
Phlorizin is known to increase whole- body glucose demand, but it has also stimulated lipolysis in past studies in ruminants. Increased lipolysis complicates studies of dry matter intake (DMI) regulation by hepatic oxidation by providing the liver with additional oxidative substrate. Therefore, to assess whether increased glucose demand selectively increases DMI for cows in negative energy balance, phlorizin was administered to early- and late-lactation cows. Six Holstein cows in early lactation (19 +/- 6 DIM, 50.0 +/- 1.8 kg/d of milk, mean +/- SD) and 6 Holstein cows in late lactation (228 +/- 18 DIM, 30.6 +/- 1.9 kg/d of milk) were randomly assigned to treatment sequence in a crossover design. Periods were 14 d with 7-d adaptation periods and 7 d of treatment. Phlorizin (4 g/d) and propylene glycol (carrier and control) were administered subcutaneously every 6 h throughout the treatment periods. Feeding behavior and DMI data were collected for the final 4 d of each treatment period; blood samples and total urine output were collected on d 4 of each treatment period. Phlorizin caused urinary loss of glucose at 333 g/d in early-lactation cows and 532 g/d in late-lactation cows. Phlorizin increased plasma nonesterified fatty acid concentrations similarly in early- and late-lactation cows, but did not significantly alter plasma insulin concentrations. Treatment with phlorizin tended to decrease meal size, but also decreased intermeal interval, resulting in no effect on DMI. The effects of phlorizin on lipolysis, feeding behavior, and DMI are not dependent on relative energy balance.