|Budget Amount *help
¥3,300,000 (Direct Cost : ¥3,300,000)
Fiscal Year 1998 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1997 : ¥2,400,000 (Direct Cost : ¥2,400,000)
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.