Prepartum DCAD and calcium concentration effects on colostrum quality and blood mineral and gas concentrations of newborn calves

Eighty-two multiparous Holstein cows were fed diets differing in dietary cation-anion difference (DCAD) and Ca concentrations in a randomized block design experiment beginning 4 wk prior to anticipated calving to determine the effects on colostrum yield and quality and acid-base balance of their calves. Treatments were arranged as a 2 X 2 factorial to provide two DCAD (-22 mEq/100 g DM [NEG] or -3 mEq/100 g DM [NEU]) and two Ca concentrations (1.3 or 1.8% of DM). Birth weight and dystocia score were not different among treatments and averaged 42.7 kg and 1.12 kg, respectively. No differences were observed in colostrum yield among treatments, which averaged 8.75 kg. Colostrum quality, as measured using a Brix refractometer, was not affected by prepartum DCAD but was higher (P = 0.0442) for 1.3 compared with 1.8% Ca: 21.58% and 19.87%, respectively. Concentrations of IgG were higher (P = 0.0034) for cows fed NEG compared with NEU and for 1.3 compared with 1.8% Ca. Calves were fed a commercial colostrum replacer to provide 200 g IgG within 4 h of birth and no difference was observed in IgG concentrations after 24 h of birth. No differences were observed in plasma concentrations of Ca, P, K, Cl, anion gap, or whole blood pH, pO2, pCO2, or SO2 of calves due to treatment. Plasma Mg (P = 0.0391) and lactate (P = 0.0591) were higher for calves born to cows fed 1.3% compared with 1.8% Ca. Interactions of DCAD and Ca were observed for plasma Na (P = 0.0232), plasma Cl (P = 0.0619), and whole blood HCO3 (P = 0.0515) due to higher concentrations observed with NEG and 1.3% Ca compared with NEG and 1.8% Ca. Feeding prepartum diets with 1.8% compared with 1.3% Ca concentrations reduced plasma Mg and lactate concentrations in calves immediately after birth and reduced Brix value of colostrum. Results of this trial indicate that feeding a fully acidified diet prepartum supported higher IgG concentrations and did not alter blood mineral or gas concentrations of calves compared with those born to dams fed a neutral DCAD diet. Feeding 1.8% Ca prepartum decreased colostrum quality as measured by Brix and IgG concentrations and altered plasma Mg and lactate concentrations.