Effects of maternal level of dietary cation-anion difference fed to prepartum nulliparous cows on offspring acid-base balance, metabolism, and growth

摘要

The objectives were to determine the effects of dietarycation-anion difference (DCAD) fed to pregnant cowsduring the last 22 d of gestation on offspring acid-basebalance, metabolism, growth, and health preweaning.A total of 132 nulliparous Holstein cows were enrolledat 250 (248 to 253) d of gestation in a randomizedblock design. Cows were blocked by genomic merit ofenergy-corrected milk yield and assigned randomly todiets varying in DCAD: +200 (P200, n = 43), −50(N50, n = 45), or −150 (N150, n = 44) mEq/kg of drymatter (DM). Newborn calves (15 males and 28 femalesin P200, 22 males and 23 females in N50, and 18 malesand 26 females in N150) were followed for the first 7 or56 d of age if males or females, respectively. Measuresof acid-base balance and concentrations of minerals inblood were measured in all calves on d 0 before colostrumfeeding, and on d 1, 3, and 7. Each calf was fed3.78 L of colostrum from the respective treatment, andapparent efficiency of IgG absorption was determined.All calves were weighed at birth, and females wereweighed again at 21, 42, and 56 d of age. Concentrationsin serum of total calcium (tCa), total magnesium(tMg), and total phosphorus (tP) were measured upto 56 d of age; intakes of milk and starter grain DMwere measured daily from 21 to 56 d of age; and incidenceof disease was recorded for the first 56 d of agein females. Treatment did not affect acid-base balancemeasured in all calves. Calves were born with metabolicand respiratory acidosis, which reversed by 1 d of age.In the first 24 h after birth, blood pH increased from7.215 to 7.421 and bicarbonate from 26.2 to 31.7 mM,whereas partial pressure of CO_2 decreased from 64.1 to48.7 mm of Hg in all treatments. Maternal DCAD didnot affect colostrum IgG content fed to calves (P200= 95.0 vs. N50 = 91.0 vs. N150 = 97.1 ± 4.1 g/L) orapparent efficiency of IgG absorption (P200 = 33.1 vs.N50 = 33.1 vs. N150 = 34.2 ± 1.9%). Males were bornheavier than females, but maternal DCAD did not affectbirth weight of all calves (P200 = 37.7 vs. N50 =37.3 vs. N150 = 37.8 ± 0.7 kg) or daily weight gain infemales in the first 56 d of life (P200 = 0.80 vs. N50 =0.81 vs. N150 = 0.77 ± 0.03 kg/d). Treatment did notaffect intake of milk (P200 = 1.11 vs. N50 = 1.04 vs.N150 = 1.19 ± 0.06 kg/d) or starter grain DM (P200= 0.27 vs. N50 = 0.27 vs. N150 = 0.21 ± 0.06 kg/d),or measures of feed efficiency. Treatment did not affectconcentrations of minerals in serum, morbidity, orage at morbidity. Manipulating the DCAD of pregnantnulliparous dams during late gestation did not affectoffspring performance in the first 2 mo of age.