title: Effects of dietary cation-anion difference on intake, milk yield, and blood components of the early lactation cow.
abstract: Early lactation Holsteins cows (15 primiparous and 18 multiparous) were offered rations with dietary cation-anion difference, calculated as mEq (Na + K - Cl - S)/100 g of feed dry matter (DCAD:S), of 20, 35, or 50 mEq from d 0 (calving) to 42 d postpartum (August 20, 2000 to January 9, 2001) to determine the effects of increasing DCAD:S on dry matter intake (DMI), milk yield, and blood metabolites. For DCAD:S of 20, 35, and 50, DMI was 3.30, 3.38, 2.96 kg/100 kg of body weight (BW); milk yield was 25.5, 24.2, and 22.4 kg/d, respectively. No differences were observed for concentration or yield of milk fat or milk protein. Serum Ca, P, Mg, Na, K, Cl, cation-anion difference, insulin, and glucose did not differ with DCAD. Serum HCO3- was 26.07, 25.88, and 27.64 mEq/L for 20, 35, and 50 DCAD:S. Serum Ca, Mg, Na, and K concentrations were greater for primiparous cows (9.52 mg/dL, 2.35 mg/dL, 140.03 mEq/L, 4.66 mEq/L, respectively) than for multiparous cows (9.27 mg/dL, 2.12 mg/dL, 137.63 mEq/L, 4.46 mEq/ L, respectively). A DCAD:S between 23 and 33 mEq/100 g of dry matter (DM) appears to be adequate during cool weather for the milk yield that occurred in the present study based on DMI (kg/100 kg of BW), whereas DCAD:S of 50 mEq/100 g of DM may be excessive and could be too alkaline or unpalatable, resulting in decreased DMI (kg/100 kg of BW).
authors.affiliation: Department of Animal and Dairy Science, University of Georgia, Coastal Plain Experiment Station, Tifton, 31793-0748, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Chan
authors.forename: J W
authors.initials: JW
authors.lastname: West
authors.forename: J K
authors.initials: JK
authors.lastname: Bernard
authors.forename: J M
authors.initials: JM
authors.lastname: Fernandez
mesh_terms: D000818:Animals; D000838:Anions / Q000008:administration & dosage*; D001639:Bicarbonates / Q000097:blood; D001835:Body Weight; D002118:Calcium / Q000097:blood; D002412:Cations / Q000008:administration & dosage*; D002417:Cattle / Q000097:blood / Q000502:physiology*; D002712:Chlorides / Q000008:administration & dosage; D004032:Diet / Q000662:veterinary*; D004435:Eating / Q000502:physiology*; D005223:Fats / Q000032:analysis; D005260:Female; D007774:Lactation / Q000502:physiology*; D008274:Magnesium / Q000097:blood; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis; D010298:Parity; D011188:Potassium / Q000097:blood; D017419:Potassium, Dietary / Q000008:administration & dosage; D011247:Pregnancy; D012964:Sodium / Q000097:blood; D012982:Sodium, Dietary / Q000008:administration & dosage; D013455:Sulfur / Q000008:administration & dosage
chemical_list: D000838:Anions; D001639:Bicarbonates; D002412:Cations; D002712:Chlorides; D005223:Fats; D008894:Milk Proteins; D017419:Potassium, Dietary; D012982:Sodium, Dietary; D013455:Sulfur; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium