Wilkens M R, Praechter C, Breves G, Schröder B
Department of Physiology, University of Veterinary Medicine, Foundation, Hannover, Germany.
J Anim Physiol Anim Nutr (Berl). 2016 Feb;100(1):156-66. doi: 10.1111/jpn.12296. Epub 2015 Feb 2.
The concept of feeding anionic salts in late gestation is widely used to prevent milk fever in dairy cows. While the effects of these diets on renal Ca excretion and tissue responsiveness towards parathyroid hormone have clearly been demonstrated, data on a potential impact on gastrointestinal Ca absorption are conflicting. Therefore, the aim of this study was to investigate the influence of feeding a diet negative in dietary cation-anion difference (DCAD) on ruminal mineral concentrations, fermentation products, electrophysiological properties of rumen epithelia and Ca flux rates. For this purpose, sheep were kept for 3 weeks on diets that were either positive or negative in DCAD. The induction of a compensated hyperchloremic metabolic acidosis could be demonstrated by increased plasma Cl and enhanced concentrations of ionised Ca, while plasma concentrations of HCO3- and base excess were decreased with the low DCAD diet. Neither transmural potential differences nor fermentation products were affected, but ruminal concentrations of Cl and Mg as well as the relation of ionised to total Ca were increased. Ussing chamber experiments revealed alterations of electrophysiological parameters and an increase in the electroneutral component of Ca flux rates from the mucosal to the serosal side of rumen epithelium. As plasma calcitriol concentrations were not affected, it can be concluded that the administration of anionic salts results in a vitamin D-independent stimulation of ruminal Ca transport.
妊娠后期饲喂阴离子盐的方法被广泛用于预防奶牛的产乳热。虽然这些日粮对肾脏钙排泄和组织对甲状旁腺激素反应性的影响已得到明确证实,但关于其对胃肠道钙吸收潜在影响的数据却相互矛盾。因此,本研究的目的是探讨饲喂日粮阴阳离子差(DCAD)为负的日粮对瘤胃矿物质浓度、发酵产物、瘤胃上皮电生理特性和钙通量率的影响。为此,将绵羊分别饲喂DCAD为正或负的日粮3周。低DCAD日粮可使血浆氯离子浓度升高、离子钙浓度增加,同时血浆碳酸氢根离子浓度和碱剩余降低,从而证实了代偿性高氯性代谢性酸中毒的诱导。跨膜电位差和发酵产物均未受影响,但瘤胃中氯离子和镁的浓度以及离子钙与总钙的比值增加。尤斯灌流小室实验显示电生理参数发生改变,瘤胃上皮从黏膜侧到浆膜侧的钙通量率的电中性成分增加。由于血浆骨化三醇浓度未受影响,因此可以得出结论,阴离子盐的施用导致了不依赖维生素D的瘤胃钙转运刺激。