title: Extended negative dietary cation-anion difference feeding does not negatively affect postpartum performance of multiparous dairy cows.
abstract: Low postpartum blood calcium remains one of the largest constraints to postpartum feed intake, milk yield, and energy balance in transitioning dairy cows. Supplemental dietary anions decrease the dietary cation-anion difference (DCAD) and reduce the risk for postpartum hypocalcemia. Prepartum management strategies aiming to minimize social stress and diet changes have resulted in a need to explore the effects of extended exposure to a negative DCAD (>21 d) diet. Holstein and Holstein-cross dairy cows (n=60) were assigned to 1 of 3 treatments 42 d before expected calving to evaluate effects of supplying anions for 21 or 42 d during the dry period on energy status, postpartum production, and Ca homeostasis. Treatments included (1) a control diet (CON; DCAD=12 mEq/100 g of DM), (2) a 21-d negative DCAD diet (21-ND; DCAD=12 and -16 mEq/100 g of DM), and (3) a 42-d negative DCAD diet (42-ND; DCAD=-16 mEq/100 g of DM). Cows fed CON were fed positive DCAD prepartum for 42 d. Cows fed 21-ND received the positive DCAD (12 mEq/100 g of DM) diet for the first 21 d of the dry period and the anionic diet (-16 mEq/100 g of DM) from d 22 until calving. Cows fed 42-ND received the anionic diet for the entire dry period. Control and anionic diets were formulated by using 2 isonitrogenous protein mixes: (1) 97.5% soybean meal and (2) 52.8% BioChlor (Church & Dwight Co. Inc.), 45.8% soybean meal. Supplementing anions induced a mild metabolic acidosis, reducing urine pH for 21-ND and 42-ND compared with CON. Prepartum DMI was not different among treatments. Postpartum DMI was higher for 21-ND compared with CON (20.8 vs. 18.1±1.1 kg/d), and 42-ND had similar DMI compared with 21-ND. During the first 56 d of lactation 21-ND had greater average milk production compared with CON (44.8 vs. 39.2±2.1 kg/d). Average milk production by 42-ND was similar to 21-ND. Postpartum total blood Ca concentration was greater for 42-ND. Cows fed anionic diets prepartum tended to have lower lipid accumulation in the liver after calving compared with CON. These data suggest low-DCAD diets fed for 21 or 42 d during the dry period can have positive effects on postpartum DMI, Ca homeostasis, and milk production.
authors.affiliation: Department of Animal Science, University of Minnesota, St. Paul, Minnesota 55108, USA.
authors.forename: W
authors.initials: W
authors.lastname: Weich
authors.forename: E
authors.initials: E
authors.lastname: Block
authors.forename: N B
authors.initials: NB
authors.lastname: Litherland
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena / Q000187:drug effects; D000818:Animals; D000838:Anions / Q000494:pharmacology; D002412:Cations / Q000494:pharmacology; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D005260:Female; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D007774:Lactation / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D010298:Parity; D049590:Postpartum Period / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D011247:Pregnancy
chemical_list: D000838:Anions; D002412:Cations
keywords: dietary cation-anion difference; hypocalcemia; transition dairy cow