Changing dietary cation-anion difference for dairy cows fed with two contrasting levels of concentrate in diets.
High-producing dairy cows are commonly fed diets containing a high proportion of rapidly degradable starch, which can cause subacute acidosis and reduce dry matter (DM) intake. Because of the properties of nonmetabolizable cations and anions, increasing the dietary cation-anion difference (DCAD = Na + K - Cl - S in mEq/kg of DM) may prevent a drop in DM intake. To test this hypothesis, 48 Holstein cows were blocked into 2 groups of 24 and assigned to two 3 x 3 Latin squares in a split-plot design. Each group received one level of concentrate at either 20% or 40% on a dry matter (DM) basis. The diet containing 20% concentrate was formulated to supply 4% rapidly degradable starch, whereas the diet containing 40% concentrate supplied 22% rapidly degradable starch. Diets in each square were formulated to provide a DCAD of 0, 150, or 300 mEq/kg of DM. The 3 values were obtained by manipulating Na and Cl contents. Intake, 4% fat-corrected milk yield, and milk fat percentage, as well as blood nonesterified fatty acids and beta-hydroxybutyrate increased with DCAD, but only on the diet providing 40% concentrate. The yield of trans-10 C(18:1) and odd-chain fatty acids decreased with increasing DCAD, whereas trans-11 C(18:1) increased. Again, this occurred only with the diet providing 40% concentrate. Blood pH and HCO(3) concentration increased along with DCAD, irrespective of the concentrate level. A positive DCAD led to increasing DM intake and fat-corrected milk yield in dairy cows fed highly degradable diets. The mechanism involved may be a localized rumen buffering effect, together with the ability of positive DCAD to maintain blood acid-base status in cows faced with a massive acid input.
Apper-Bossard
E
E
Unité Mixte de Recherches INRA-Agrocampus Production du Lait, Domaine de la Prise, 35590 Saint-Gilles, France.
Peyraud
J L
JL
Faverdin
P
P
Meschy
F
F
D020155:3-Hydroxybutyric Acid / Q000097:blood; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000838:Anions; D001639:Bicarbonates / Q000097:blood; D001769:Blood; D002412:Cations; D002417:Cattle / Q000502:physiology*; D002712:Chlorides / Q000008:administration & dosage; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D005223:Fats / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006863:Hydrogen-Ion Concentration; D007774:Lactation; D008892:Milk / Q000737:chemistry; D008903:Minerals / Q000032:analysis / Q000097:blood; D017419:Potassium, Dietary / Q000008:administration & dosage; D012982:Sodium, Dietary / Q000008:administration & dosage; D013213:Starch / Q000008:administration & dosage; D013455:Sulfur / Q000008:administration & dosage
D000838:Anions; D001639:Bicarbonates; D002412:Cations; D002712:Chlorides; D004044:Dietary Proteins; D005223:Fats; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D008903:Minerals; D017419:Potassium, Dietary; D012982:Sodium, Dietary; D013455:Sulfur; D013213:Starch; D020155:3-Hydroxybutyric Acid