Study on mineral components and untasty flaver in milk of cows fed excessive salt.

这项研究的目的是阐明岩手县C农场奶牛分泌往往不好吃的牛奶的原因。结果表明：1.有咸味和怪味的奶牛，牛奶中NaCI含量较高，Na/K浓度比失衡，说明TMR中的酱油饼和矿物质混合物导致奶牛食盐过多(160~170g/头/天)。对C农场所在的4个农场和2个参照点的奶牛乳中矿物质成分进行比较，发现pH值分别与磷(P&lt；0.001)、氯与磷(P&lt；0.05)、钠与钾(P&lt；0.001)呈显著负相关。以奶粉、氯化钠、氯化钾为原料，在不同浓度的钠、钾(10-50mlA)中，对5种牛奶进行了口感试验。随着Na浓度的升高和K浓度的降低，牛奶中盐度升高，甜度降低。在16天内，5头奶牛饲喂过量食盐(200g/头/天)，结果表明，过量食盐降低了奶牛的摄水量，降低了血清钠浓度，增加了乳汁和尿液中的钠、氯浓度，降低了乳汁和尿液中的钾浓度，提高了乳中钠/钾的浓度比，降低了3头奶牛的血浆心钠素浓度，并使3头奶牛排出了难吃的牛奶。给4头奶牛静脉注射抑制特异性钠泵(Na-K-ATPase)的哇巴因，可降低血清Na浓度，升高乳汁和尿液中Na、Cl浓度，降低乳汁和尿液中K浓度，提高乳中Na/K浓度比，排出难吃的牛奶。结论：过量食盐奶牛体内可能存在钠泵抑制，导致牛奶中Na/K比例失衡，从而产生不良牛奶。

This study aimed to clalify the cause of which cows secreted often untasty milk in the C farm in Iwate Prefecture.1. The untasty milk in cows which had salty and strange tastes showed high NaCi concentration and imbalance of concentration rasio of Na/K, and it became clear that those cows were fed excessive salt(160-170g/head/day) caused by soy sauce cake and mineral mixture in TMR.2. In comparison of mineral components in milk of cows in 4 farmes contained the C farm and in 2 referenes, there were significantly negative correlations between pH and P(P<0.001), Cl and P(P<0.05), and Na and K(P<0.001), respectively.3. A tasty test was done by 8 panelors for 5 milks in different concentration of Na and K(10-50mlA) prepared with milk powder, NaCi and KC1. As Na concentration increased and K concentration decreased, salinity increased and sweetness decreased in milk.4. Five cows were fed excessive salt(200g/head/day) during 16 days and it resulted in decreased water intake, lowered Na concentration in serum, increased Na and Cl concentrations in milk and urine, decreased K concentrations in milk and urine, increased concentration rasio of Na/K in milk, lowered plasma ANP concentration in 3 cows and secretion of the untasty milk in those 3 cows.5. Four cows were intravenously injected of the ouabain which inhibited specificity Na pump(Na-K-ATPase) and it resulted in lowered Na concentration in serum, increased Na and Cl concentrations in milk and urine, decreased K concentrations in milk and urine, increased concentration rasio of Na/K in milk, secretion of the untasty milk.6. It is concluded that the inhibition of Na pump which may be induced in cows fed excessive salt results in imbalance of Na/K in milk and consequently produces the untasty milk.