Effects of dietary cation-anion difference and nicotinic acid supplementation on prepartum Jersey cows and calves I: Impacts on cows, colostrum production, bioactive compounds, and fatty acids

Diets with 2 different DCAD (-40 or -80 mEq/kg) and with or without (+ or -) 23 g/d supplemental nicotinic acid (NA) were fed to prepartum Jersey cows. Cow performance and colostrum composition have been studied, but NA supplementation of prepartum Jersey cows has not been previously studied. To meet this objective, 40 multiparous Jersey cows were blocked by calving date and assigned to treatments. Treatments were administered for 29 d prepartum. Treatments were -40 mEq/kg without NA (-40/NA-), -40 mEq/kg with 23 g/d NA (-40/NA+), -80 mEq/kg without NA (-80/NA-), and -80 mEq/kg with 23 g/d NA (-80/NA+). Body weight was measured, and blood samples were collected weekly for nonesterified fatty acids (NEFA), ketones, and IgG analyses. Urine was collected thrice weekly for pH, creatinine, and purine derivatives (PD) analyses. Calves were separated from their dams and had their navels dipped in an iodine solution immediately postpartum. Colostrum was collected within 90 min after parturition. Results from the calves used in this study are presented in a companion paper. The statistical model was a randomized complete block design with a factorial arrangement of treatments. The main effects were DCAD level and inclusion of NA. We found no differences in grain or hay intake, DMI, weekly BW, ADG, NEFA, ketones, urine pH, and urinary PD concentrations of allantion and total PD. For urine volume, there was an NA by week interaction. Uric acid tended to be lowered in the -80 diets; there was a DCAD by week interaction and a tendency for an NA by week interaction. We found no differences in yields of colostrum, protein, and IgG, and concentrations and yields of IGF-1, lactoferrin, and TGF-β1. We observed a trend for an interaction with IgG concentration, where -80/NA+ resulted in the lowest concentrations of IgG. We observed an interaction with colostrum protein percentage, with the lowest for the -40/NA- treatment and the highest -40/NA+ treatment. Nicotinic acid supplementation decreased colostrum fat percentage and tended to reduce fat yield. We observed a tendency to reduce colostral insulin concentrations with -40 DCAD diets, but no differences in insulin yields. We observed a tendency for an interaction with TGF-β2 concentration, with the lowest concentration at -40/NA+, but no differences in TGF-β2 yields. Fatty acid (FA) content tended to be lower in the colostrum of cows fed NA and lowered many FA in the colostrum of cows fed the -80 DCAD diets. However, we found no differences across treatments when FA were expressed as yield (g), except for an interaction in preformed FA, where colostrum of cows fed -40/NA+ had the lowest amount. These data suggest that NA may have reduced microbial protein synthesis, resulting in less de novo synthesis of FA and a decrease in lipolysis and leading to a reduction in preformed FA. Moreover, data suggest that providing Jersey cows with 23 g/d NA supplementation may not be beneficial when supplemented to cows fed a -80 mEq/kg DCAD diet due to its effect on IgG.