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Abstract High producing dairy cows may suffer hypocalcaemia after parturition because of losing Ca in milk. Hypocalcaemia is known as milk fever and it may be clinical or subclinical. Milk fever causes decreasing milk production and may lead to the death. Milk fever is known also to be associated with some metabolic disorder, such as: ketosis, fatty liver and / or some reproductive problem, such as: retained placenta, mastitis and metrities, So, to avoid all previous, we should care about transition period which is a critical period. It starts three weeks before parturition (Close up period) up to three weeks after parturition (early lactation period). Interest in this period avoids the occurrence of diseases and reduces the lack of production by about 14% and the lack of seasons by 3 to 4 seasons compared to animals with careless in this period. The main objective of this study was to investigate the effect of pre-parturient DCAD levels on milk fever, rumen fermentation, digestibility, milk production and productive and reproductive performance of lactating Holstein cows. Dietary cation anion balance (DCAB) can be used to determine the relationship between cations which have a positive charge like sodium (Na), potassium (K), magnesium (Mg) and calcium (Ca), and anions which have a negative charge such as chloride (cl) and sulfur (S). Cations in the diet promote more blood alkaline (higher pH), which is associated with milk fever. Anions promote blood acidity (lower pH) which is associated with reduced incidence of milk fever. DCAD is expressed as mille Equivalents (mEq)/100g DM or mEq/kg DM. Several equations has been suggested to calculate DCAD: (Na+ + K+ ) – (Cl- + S-) = mEq/100 gm of DM. (Tucker et al., 1992b) Twenty Late pregnant Holstein cows (3 to 4 weeks before calving) were used through the experiment. Animals were divided according to the parity to four groups, five cows each. Animals were housed in four separate open areas provided with water sinks and shades. Animals were tied at feeding time to be fed individually according to NRC (2001). All groups were fed a basal diet consisting of berseem 30Kg, concentrate feed mixture (CFM) 6Kg, rice straw 6 Kg &soya bean meal (SBM) 75g as a carrier for anionic salts/head/day. Cows were divided randomly into four groups, five cows each. All animals were fed on the basal diet and the following additives Treatment (1) : Control group received soybean meal without anion salts (soybean meal was used as a carrier for anionic salts which added to other groups). Treatment (2) : Received (150 gm) anionic salt to achieve DCAD equal zero mEq /Kg DM. Treatment (3) : Received (350 gm) Soybean meal + anionic Salt to achieve DCAD equal (-150) mEq /Kg DM. Treatment (4) : Received (350 gm) Anio-Norel compound to achieve DCAD equal (-150) mEq /Kg DM. Results as the following 1. Results indicated that serum calcium concentration increased significantly (p < 0.05) with decreasing DCAD. With positive DCAD (+90mEq/Kg DM) serum calcium concentration was (6.944 mg/dl), increased significantly to (7.589 mg/dl) with (zero DCAD). When DCAD decreased to (-150 /mEq/Kg DM), serum Calcium concentration increased to (8.133 & 8.367 mg/dl) with anionic salts & Anio-Norel, respectively with no significant differences between (group 3 & group 4). 2. Data showed that urinary calcium concentration had the same trend of blood calcium concentration. Urinary calcium concentration increased with decreasing DCAD level from (1.001 mg/dl) for (+90 mEq/Kg/DM) up to (2.156 mg/dl) for (-150 mEq/kg/DM). However, there was a significant difference (p < 0.05) between (group 3& group 4).3. Data showed that blood magnesium concentrations had no significant differences (p< 0.05) among groups where it ranged between (2.189 mg/dl) for (+90 mEq/kg DM) DCAD level and (1.677 mg/dl) for (–150 mEq/Kg DM ) DCAD level. 4. Results indicated that urinary magnesium increased with decreasing DCAD level. Values were (2.714 mg/dl) for animals fed diets with DCAD (+ 90 mEq/kg DM) and (4.192 mg/dl) for DCAD level (-150 mEq/kg DM). However, there was no significant difference between (group 3 & group 4). 5. Results indicated that serum phosphorus concentration decreased with decreasing DCAD level. 6. Urinary phosphorus concentrations were not affected by time before or after parturition. 7. Results indicated that urinary pH decreased from (8.111) for group 1 to (6.578) in group 4. However, there were no significant differences between group 1 and 2 (8.111 and 7.978) respectively. While group (3) 7.022 decreased significantly than group 1 and 2. group 4 (6.578) decreased significantly when compared to group 3. Urinary pH did not differ significantly before and after parturition (7.400) and (7.441) respectively. 8. The present values of serum total protein, Albumin, Globulin and A/G ratio are within the normal range and not affected with treatments. 9. The present values of serum ALT (GPT) and AST (GOT) are also within the normal range. 10. The present values of serum createnine and Urea are within the normal range. 11. Data indicated that there was a significant interaction between treatment and time before and after parturition effects on BHBA concentration. This interaction was reflected in the following observation: 1. At 7 days before parturition there were no significant differences among groups 2. On the day of parturition group 1 had the highest BHBA concentration (8.943 mg/dl) followed by group 2 & 3 (7.743, 7.730 mg/dl), respectively and the lowest was for group 4, with no significant difference between group 2 & 3. 3. At 7 days after parturition group 3 & 4 showed the lowest BHBA concentration with no significant difference between them. group 2 had significantly higher BHBA concentration than group 3 & 4. 4. group 1 had the highest BHBA concentration (10.000 mg/dl). 12. Results indicated that milk yield was lowered by treatment (3) compared with the other groups which had statistical similar values. These values of milk production may reflect the dry matter intake through the transitional period. 13. The relationship in monthly milk production tended to be linear in treatments (1&2) while it was more quadratic in treatment (4) revealing more persistence for Anio-Norel group. 14. Data showed a trend of lowered dry matter intake with more anionic diets. (Decreased in DCAD). 15. Rumen pH tended to be lower with treatments (2) and (3) where anionic salts were added to the diet, compared with control group. However when Anio- Norel was used the pH values increased, to be similar to treatment (2) (p< 0.05) but still significantly less than control and more than treatment (3) (p> 0.05).This can be explained by buffer effect of yeast and magnesium oxide included in Anio- Norel mixture. Total volatile fatty acid concentrations were increased with treatments (2) and (3) when compared with control and Anio- Norel groups. Ammonia concentrations were lower with treatments (2) and (3) (14.8mg/100ml) while they were higher for control and Anio- Norel groups (16.4, 16.3 mg/100ml), respectively. 16. When Acid Insoluble Ash (AIA) and Acid Detergent Lignin (ADL) were used to calculate the digestibility of nutrients, values obtained were in general higher significantly (p>0.05) for ADL when compared with AIA. This is true for all nutrients except for crude protein where differences were not significant. 17. Results indicated that progesterone decreased dramatically at parturition where it was 1.64 ng/dl (7 days pre-partum) to 0.285 ng/dl at parturition and 0.468 ng/dl (7 days post-partum). |