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With the depth theoretical study of the metabolism of dairy cattle nutrition, dietary cation-anion difference (dietary cation-anion difference, DCAD) caused widespread concern of the dairy cow nutrition researchers. The DCAD means per kg diet dry matter contained in the main cation (Na, K) of the millimoles with major anions (Cl-, S2-) mm of the difference between the number of moles. This research systems of different the DCAD level and complement Ca parous Holstein cows perinatal (test, test) (test) body fluid acid-base balance, blood minerals, health and production performance and lactation peak impact; based on components of Zhejiang Province, six large pasture cows diets cation-anion difference (CAD) profit and loss situation research and calculate the typical DCAD level (test). The trial is a research to reduce DCAD levels of perinatal the cows body fluid acid-base balance, blood mineral content, health and production performance. Test using a randomized block design, similar to the 40 conditions in the prenatal 21 days cows were divided into 4 groups: control group, the test group 1, test 2 group and the test group 3, n = 10; level of Design cows DCAD respectively 150, 50, -50, -150 mmol / kg DM (actually measured as 127, 30, -63, -154 mmol / kg DM). The test results are as follows. As DCAD lower level, cow urine pH, blood pH significantly decreased (P lt; 0.05), HC03-concentration in the blood is a downward trend (P gt; 0.05). DCAD levels and urine pH, blood pH, blood HC03-coefficient of determination (r2) were 0.85 (P lt; 0.0001), 0.28 (P lt; 0.01), 0.09 (P gt; 0.1), urine pH and blood the pH of the correlation coefficient (r) was 0.52 (P lt; 0.0001). Visible, reduce the the DCAD level induced cows mild metabolic acidosis. And group 2 test three groups cow plasma calcium levels were significantly higher than that of the control group and the experimental group (P lt; 0.05), the other difference is not significant (P gt; 0.05); test three groups of cows was significantly higher than in plasma magnesium content the other groups (P lt; 0.05); affect all the cows plasma phosphorus levels from DCAD (P gt; 0.05). All the cows plasma calcium content calving are the lowest in the day, but the test group, test group calving near days compared with the control group (P lt; 0.05). Lower DCAD level to maintain cows blood calcium Steady. No cows fat production of milk fever. Test group, test group cows incidence of hypocalcemia head (0,0) compared to the control group, the test group (2,3), The afterbirth incidence of head (0,0) was significantly lower than the control group (4 ; P lt; 0.05). Reduce DCAD levels conducive to improving the the cows health (control group, test group 1 and group 2, the test group of cows onset total number of head 10,7,3,2). Different DCAD levels of dry matter intake the amount (DMI), milk production, milk composition did not produce significantly different (P gt; 0.05). Be seen from the results of this test, the late dry milk low DCAD level diet can induce cows were mild metabolic acidosis, maintain blood calcium Steady, thereby reducing the incidence of the disease and improve health. Test two complement anionic DCAD diets based on Ca perinatal the cows body fluid acid-base balance, blood mineral content, health and production performance. Selected conditions similar test, in cows 36 dry late (prenatal 20 days), divided into three groups: control group according to a randomized block design, test group 1, test group 2, n = 12; level of Design cows DCAD respectively 150, -100, -100mmol/kgDM (actually measured to 185, -67, -67mmol/kg DM), Ca intake were 84,84,114 g / d (the actual measured level of 100,100,130 g / d). Compared with the control group, the test group, test group 2 cows urine pH, blood pH significantly reduce (P lt; 0.05), blood HC03-concentration difference is not (P gt; 0.05); Group 1 test, test 2 groups of various body fluid acid-base balance target levels close to, the difference was not significant (P gt; 0.05). DCAD levels and urine pH, blood pH, blood HC03-coefficient of determination (r2) were 0.92 (P lt; 0.0001), 0.57 (P lt; 0.01), 0.02 (P gt; 0.1), urine pH and blood the pH of the correlation coefficient (r) was 0.77 (P lt; 0.0001). Be seen, the two groups of anionic DCAD diets induced cows mild metabolic acidosis. The test cow serum calcium content was significantly higher than that of the control group and test group 2 (P lt; 0.05), control group and test group differences were not significant; serum phosphorus levels were significantly higher than those in the control group (P lt; 0.05); trial 2 serum magnesium concentration than the test group (P lt; 0.05). 0.5 days after calving, cows plasma calcium content are minimum values, but group 1 was 0.5 days postpartum, two days of serum calcium levels significantly higher than those in the control group (P lt; 0.05), test group and control group difference not significant (P gt; 0.05). The results suggest that calcium anionic DCAD diets based on the maintenance of the effects of perinatal cows blood calcium level is not obvious. There is no the cows fat production of milk fever or abomasal shift. Test a group of cows hypocalcemia onset head count was significantly lower than the control group (0 vs.4; P lt; 0.05) and group 2 cows afterbirth the incidence first few significantly lower than the control group (1 vs.6; P lt; 0.05). Quite anionic DCAD diets based on calcium and anionic DCAD diets improve cow health effects (control group, the test group 1 and group 2, respectively 14,4,4 cows sick). Dietary treatment of all the cows DMI, milk production, milk composition did not significantly affect (P gt; 0.05). The test results showed that the anionic DCAD diets (-100mmol/kg DM) on the basis of calcium can also be induced by perinatal cows were mild metabolic acidosis, but to maintain the dairy calcium Steady, improve health no further effect. Test three different DCAD levels of the the lactation peak cows blood acid-base balance, serum mineral content and production performance. Test using a 3 × 3 the complex Latin square design, the the lactation peak 15 cows (postnatal 20-50 d) divided into 3 groups: control group, test group 1 and group 2, n = 5, Design DCAD levels were 250, 400, 550 mmol / kg DM (actually measured as 242, 389, 538 mmol / kg DM). The results showed that, the cows blood acid-base balance, serum mineral content of milk production from DCAD effects of (P gt; 0.05). Test four pairs of Zhejiang Province, 6 large pastures dairy cow diets commonly used feed ingredients Na, K, Cl, S content of its CAD position in terms of profit and loss investigation and calculation of a typical DCAD level. CAD the average dairy concentrate mixture of the main raw material of corn, soybean meal, wheat bran were 26,275,147 mmol / kg DM, followed by the highest soybean meal, wheat bran, corn lowest. The average of the dairy concentrate mixture of the dry period and lactation peak CAD were 227,323 mmol / kg DM, dry period concentrate mixes CAD value. The cows roughage main raw material for the whole plant silage corn, L. chinensis hay, alfalfa hay CAD average were -50,95,429 mmol / kg DM, alfalfa hay highest, followed by L. chinensis hay, whole plant silage corn lowest. Simulate the typical dry period and lactation peak CAD the average dairy cow diets were 74,214 mmol / kg DM, dry period DCAD level than the lactation peak DCAD levels. In summary, perinatal cows were fed the CAD level -100 ~~ -50 mmol / kg DM diet-induced body mild metabolic acidosis maintain blood calcium Steady, improve health, but will not affect production performance; anionic DCAD diets based on calcium (30 g / d), on the improvement of these indicators effect is not obvious; lactating the peak dairy cows blood acid-base balance, serum mineral content of the milk production from DCAD levels. The six accepted the large research pastures typical dry cows DCAD average is positive, should be added anionic salts to reduce the the DCAD level, the level of lactating the peak dairy cows DCAD more appropriate.
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