Abstract #215
Section: Physiology and Endocrinology (orals)
Session: Physiology & Endocrinology 1
Format: Oral
Day/Time: Monday 2:30 PM–2:45 PM
Location: Room 233
Session: Physiology & Endocrinology 1
Format: Oral
Day/Time: Monday 2:30 PM–2:45 PM
Location: Room 233
# 215
Influence of prepartum dietary cation-anion difference and the decline of calcium at the onset of lactation.
M. K. Connelly*1, R. M. R. Harris5, F. S. Andrade6, J. P. Nascimento Andrade6, J. Kuehnl1, A. Beard1, E. Block4, I. J. Lean2,3, L. L. Hernandez1, 1Department of Dairy Science, University of Wisconsin-Madison, Madison, WI, 2Scibus, Camden, NSW, Australia, 3School of Life and Environmental Sciences, Faculty of Veterinary Science, University of Sydney, Camden, NSW, Australia, 4Arm & Hammer Animal Nutrition, Princeton, NJ, 5National Centre for Epidemiology and Population Health, Research School of Population Health, Australian National University, Canberra, Australia, 6Federal Rural University of Rio de Janeiro, Seropedica, RJ, Brazil.
Key Words: calcium, dietary cation-anion difference (DCAD)
Influence of prepartum dietary cation-anion difference and the decline of calcium at the onset of lactation.
M. K. Connelly*1, R. M. R. Harris5, F. S. Andrade6, J. P. Nascimento Andrade6, J. Kuehnl1, A. Beard1, E. Block4, I. J. Lean2,3, L. L. Hernandez1, 1Department of Dairy Science, University of Wisconsin-Madison, Madison, WI, 2Scibus, Camden, NSW, Australia, 3School of Life and Environmental Sciences, Faculty of Veterinary Science, University of Sydney, Camden, NSW, Australia, 4Arm & Hammer Animal Nutrition, Princeton, NJ, 5National Centre for Epidemiology and Population Health, Research School of Population Health, Australian National University, Canberra, Australia, 6Federal Rural University of Rio de Janeiro, Seropedica, RJ, Brazil.
The onset of lactation results in a large and sudden increase in calcium (Ca) demand by the mammary gland to synthesize milk. The ensuing drop in circulating Ca plays a factor in the cow’s metabolic adaptation to lactation. When Ca maintenance fails, cow health and productivity is affected. Negative dietary cation-anion difference (DCAD) diets have been utilized to create metabolic conditions favorable to maintaining blood Ca concentrations. The objective of this study was to determine how the decline in Ca at the onset of lactation, in combination with positive or negative DCAD diets, alters Ca metabolism postpartum. Thirty-two multiparous Holstein cows were blocked by parity and 305d production in a randomized complete block design. Cows were fed a negative (−120 mEq/kg; −DCAD) or positive (+120 mEq/kg; +DCAD) DCAD diet from 251 d of gestation until parturition (n = 16/diet). Immediately after calving cows were continuously infused for 24 h with (1) an intravenous solution of 10% dextrose or (2) Ca gluconate (CaGlc) to maintain blood ionized Ca (iCa) concentration at 1.2 mM (normal calcemic) forming 4 treatment groups (n = 8/treatment). From 3 d pre- to 3 d postpartum, blood was collected every 6 h to monitor iCa concentrations. Groups were compared using a mixed model ANOVA with time included as a repeated measure. Cows fed −DCAD had increased iCa concentrations compared with +DCAD cows during the 72 h prepartum (P = 0.01) and immediately before start of infusion (P < 0.05). Twelve hours after termination of infusion (36 h post parturition) cows infused with CaGlc had decreased iCa concentrations compared with cows infused with dextrose (P = 0.0003). Cows in +DCAD/CaGlc group had decreased blood iCa compared with all other treatments 36 h postpartum (0.88 ± 0.03 mM; P < 0.05). Treatment with CaGlc during the 24 h after parturition negatively affected the immediate postpartum Ca homeostasis, regardless of prepartum dietary treatment. Additionally, feeding -DCAD better equipped cows to respond to Ca requirements at the start of lactation.
Key Words: calcium, dietary cation-anion difference (DCAD)
