Effect of different potassium levels in hay on acid-base status and mineral balance in periparturient dairy cows
Effect of different potassium levels in hay on acid-base status and mineral balance in periparturient dairy cows
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DOI：
10.3168/jds.2009-2449
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发表时间：
2009-12-01
影响因子：
3.5
通讯作者：
Liesegang, A.
中科院分区：
文献类型：
--
作者：
Rerat, M.;Philipp, A.;Liesegang, A.
干奶牛日粮中常用的饲料含有高浓度的钾。这会导致日粮阳离子-阴离子差异（DCAD）较高，从而损害围产期奶牛的钙稳态。本研究的目的是确定产前期间饲喂的两种不同钾浓度的干草对奶牛围产期酸碱状态和矿物质平衡的影响。在预产期，K（33）组（n = 6）的奶牛接受高钾浓度（33 g/kg DM）干草的日粮，而K（13）（n = 6）组的奶牛接受低钾浓度（13 g/kg DM）干草的日粮。两种实验饮食均配制为等能量和等氮的。产犊后，所有奶牛都接受基于干草 K(33) 的相同饮食。在分娩前第 14 天、第 7 天和第 3 天、分娩时以及产犊后的前 8 天每天采集血液和尿液样本。对血液和尿液中矿物质的浓度进行了分析。还测量了尿液中的肌酐，以计算矿物质：肌酐比率。产前第 14、7、3 天、分娩时和产后第 1 天测定血液（pH 和 HCO(3)(-) 浓度）和尿液（pH、净酸碱排泄量和碱酸商）中的酸碱参数。使用干草 K(13) 将产前饮食的 DCAD 值降低了一半（195 mEq/kg DM 与 514 mEq/kg DM）。两组间血液酸碱指标和血浆矿物质除血浆镁浓度无显着差异外，K(13)组产前第3天至产后第2天镁浓度有较高趋势。 K(13)组从产前第3天至产后第1天尿Ca排泄量高于K(33)组。产前第3天，K(13)组尿pH值和净酸碱排泄量显着低于K(33)组。产前第14、7、3天，K(13)组碱酸商显着低于K(33)组。 K(13)组的每日采食量以及产后第3天和第4天期间Ca、P和Mg的每日摄入量均高于K(33)组。通过在分娩前饲喂低 K 干草，DCAD 在正范围内降低，导致代谢碱电荷减少（如尿液酸碱参数中所观察到的），并且由于泌乳开始时采食量较高而增加了 Ca 和 P 的利用率。
Forages commonly used in dry cow rations contain high K concentrations. This results in a high dietary cation-anion difference (DCAD), which can compromise the calcium homeostasis of periparturient cows. The aim of this study was to determine the effect of 2 types of hay, fed during the prepartum period and differing in their K concentrations, on the peripartum acid-base status and mineral balance of dairy cows. During the prepartum period, the cows of group K(33) (n = 6) received a diet based on hay with a high K concentration (33 g/kg of DM), whereas the cows of group K(13) (n = 6) received a diet based on hay with a low K concentration (13 g/kg of DM). Both experimental diets were formulated to be isoenergetic and isonitrogenous. After calving, all cows received the same diet based on hay K(33). Blood and urine samples were taken on d 14, 7, and 3 before parturition, at parturition, and then daily during the first 8 d after calving. Concentrations of minerals were analyzed in both blood and urine. Creatinine was also measured in urine for the calculation of the mineral: creatinine ratio. The acid-base parameters in blood (pH and HCO(3)(-) concentration) and urine (pH, net acid-base excretion, and base-acid quotient) were determined on d 14, 7, and 3 before parturition, at parturition, and on d 1 after parturition. The use of hay K(13) reduced the DCAD value of the prepartum diet by half (195 vs. 514 mEq/kg of DM). No significant differences between the 2 groups were observed for blood acid-base indicators or plasma minerals except for the Mg plasma concentration, which tended to be higher in group K(13) from d 3 prepartum to d 2 after calving. In group K(13), urinary Ca excretion tended to be higher from d 3 prepartum to d 1 after parturition than that in group K(33). On d 3 before parturition, urinary pH and net acid-base excretion were significantly lower in group K(13) than in group K(33). On d 14, 7, and 3 before parturition, base-acid quotient was significantly lower in group K(13) than in group K(33). In group K(13), daily feed intake and hence daily intake of Ca, P, and Mg during d 3 and 4 after parturition were higher than in group K(33). The decrease of the DCAD in positive ranges by feeding a low-K hay before parturition induced a reduction of the metabolic alkalotic charge, as observed in acid-base parameters in urine, and increased the availability of Ca and P as a result of higher feed intake at the onset of lactation.