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

本研究的目的是阐明岩手县C农场奶牛分泌的牛奶经常不好吃的原因。牛奶不好喝的奶牛有咸味和怪味，表现为NaCl浓度高和Na/K浓度比值不平衡，这表明这些奶牛在TMR中饲喂了由酱油饼和矿物质混合物引起的过量盐（160 - 170 g/头/天）。C农场所属4个奶牛场和2个参比奶牛场乳中矿物质成分比较，pH与P（P <0.001）、Cl与P（P <0.05）、Na与K（P <0.001）呈极显著负相关.用奶粉、NaCl和KCl配制不同Na和K浓度（10 - 50ml/A）的5种牛奶，由8个小组进行口味试验。随着牛奶中Na浓度的增加和K浓度的降低，牛奶中的盐分增加，甜度降低. 5头奶牛在16天内过量饲喂食盐（200 g/头/天），导致饮水量减少，血清钠浓度降低，乳和尿钠、氯浓度升高，乳和尿钾浓度降低，乳钠/钾比值升高，3头奶牛血浆心钠素浓度降低，3头奶牛分泌的奶味不佳.给4头奶牛静脉注射哇巴因，抑制特异性钠泵（Na-K-ATP酶），导致血清钠浓度降低，乳和尿钠、氯浓度升高，乳和尿钾浓度降低，乳钠/钾比值升高，产奶不良.因此，高盐日粮可诱导奶牛体内钠泵功能受到抑制，导致乳中Na/K失衡，从而导致乳味不良。

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.