1541 Effect of level of dietary cation–anion difference and duration of prepartum feeding on calcium and measures of acid–base status in transition cows

Effects of the level and duration of maternal diets with negative dietary cation-anion differences prepartum on calf growth, immunity, and mineral and energy metabolism

“…Specifically, in sheep, pigs, and guinea pigs, it has been shown that increased Ca in the pregnant dam does not have a significant effect on fetal plasma Ca concentrations (Bawden and Wolkoff, 1967;Greeson et al, 1968;Abbas et al, 1987). Despite the differences observed the last 14 d prepartum in concentrations of iCa in the dams fed −180 DCAD prepartum compared with the dams fed −70 DCAD prepartum (1.282 vs. 1.252 mM for −180 and −70 DCAD, respectively; Lopera et al, 2016), iCa concentrations at birth in the heifers did not differ with dam treatment. Interestingly, it was observed that at 3 d of age, heifers born to −180 DCAD dams had increased concentrations of iCa relative to birth, whereas in heifers born to −70 DCAD dams those concentrations remained unaltered between birth and 3 d of age.…”

“…12, 2017 from 0 to 3 d of age; however, it is possible that even by 3 d of age, lung capacity to compensate for the metabolic acidosis remains less than optimal compared with that in adult animals. The inability for respiratory compensation likely justifies the much smaller blood pH in calves at birth compared with the results from their dams that averaged 7.416 ± 0.005 and 7.383 ± 0.005 for −70 and −180 DCAD, respectively, before calving (Lopera et al, 2016). Overall, neither the more acidogenic diet nor the extended duration of feeding negative DCAD prepartum to dams induced a noticeable uncompensated metabolic acidosis in their calves.…”

“…Feeding acidogenic diets, by reducing the DCAD from +130 to −130 mEq/kg, does not influence colostrum yield or nutrient content of IgG concentration [N. Martinez (University of Florida, Gainesville), R. Rodney (SB-Scibus, Camden, NSW, Australia), E. Block (Church and Dwight Co. Inc., Princeton, NJ), L. L. Hernandez (University of Wisconsin, Madison), C. D. Nelson (University of Florida, Gainesville), I. J. Lean (University of Sydney, Camden, NSW, Australia), and J. E. P. Santos (University of Florida, Gainesville), , unpublished data], and reducing the DCAD from −70 to −180 mEq/kg did not alter colostrum yield or composition (Lopera et al, 2016). However, pooled colostrum was fed to the newborn calves to minimize any minor differences in nutrient content to test the concept of changes in calf acid-base status on IgG absorption.…”

“…Metabolic acidosis is characterized by imbalances in the HCO 3 − buffer system, whereas respiratory acidosis is characterized by imbalances in pCO 2 ; both imbalances can cause blood pH to fall below a normal range of 7.40 to 7.50 in cows. In the companion experiment (Lopera et al, 2016), dams fed the −180 DCAD experienced a compensated metabolic acidosis based on smaller urinary pH (−180 DCAD = 5.46 vs. −70 DCAD = 6.38), pCO 2 (−180 DCAD = 38.9 vs. −70 DCAD = 40.1 mmHg), and HCO 3 − (−180 DCAD = 23.2 vs. −70 DCAD = 26.0 mM). On the contrary, heifers born to −70 DCAD dams had a more evident metabolic acidosis at birth because they had a more acidic blood pH and their pCO 2 was greater compared with those born to dams fed the −180 DCAD.…”

“…Samples of forages and concentrates were collected weekly and analyzed for their chemical composition to ensure desired negative DCAD levels. Details of diet sampling and analyses are presented elsewhere (Lopera et al, 2016). Briefly, samples of individual ingredients were collected weekly, processed, and composited into 5 monthly samples that were subjected to chemical analyses.…”