|Holden, L - PENN STATE UNIVERSITY|
Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 20, 1999
Publication Date: November 13, 1999
Citation: Soder, K.J., Holden, L.A. 1999. Use of anionic salts with grazing prepartum dairy cows. Professional Animal Scientist. 15(4):278-285. Interpretive Summary: Northeastern dairy producers have expressed increasing interest in grazing late pregnancy dairy cows as a low cost forage source. However, pastures typically contain high levels of potassium; high dietary potassium has been linked to increased risk of metabolic problems at calving. Anionic salts in the ration have proven effective in confinement situations in decreasing grisk of metabolic problems. However, anionic salts have not been evaluate with late pregnancy dairy cows grazing pasture. Therefore, 24 grazing late pregnancy dairy cows were fed a grain pellet with or without anionic salts. The cows grazed as a single group and were individually fed their respective supplements. Cows calved on pasture, and then were integrated into the regular milking herd and fed a total mixed ration. No clinical cases of milk fever were observed in either group. Blood and urine mineral profiles were not generally affected by treatment. Milk yield and composition after calving also were not affected by treatment. Based upon the results of this study, the addition of anionic salts to the diet of grazing late pregnancy dairy cows did not affect health or productivity when compared to the control treatment. Therefore, these relatively expensive supplements may not be economically practical for grazing cows. More research is required to evaluate the effects of high potassium levels in pasture on animal health and productivity.
Technical Abstract: Twenty multiparous and four primigravid Holstein cows were utilized in a completely random design to characterize the influence of decreasing dietary cation anion difference (DCAD) from +388 meq/kg to +183 meq/kg on DMI, prepartum blood profiles, and postpartum milk yield and composition of grazing cows. Treatments began wk 4 prepartum and consisted of 1) pasture eand grain pellet without anionic salts (CON; +388 meq/kg), or 2) pasture and grain pellet containing anionic salts (ANION; +183 meq/kg). Cows were rotationally grazed as a single group and individually fed pellets twice daily at a rate of 0.5% of BW/d. Blood and urine samples were collected on wk -4, -2.5, and -1 prepartum and analyzed for Ca, Mg, K, Na, and Cl concentrations. Urine samples were also analyzed for pH. Chromic oxide was dosed twice daily during the last 4 wk of gestation, and again for 10 d during wk 4 and 12 postpartum for estimation of intake. Cows calved on pasture, then were integrated into the regular milking herd and fed a tota mixed ration. Daily milk yield and weekly milk samples were collected through wk 14 of lactation. Prepartum and postpartum DMI, milk yield and composition, and plasma minerals were not affected by treatment. No clinical cases of milk fever were observed for either treatment group. Reducing DCAD from +388 to +183 meq/kg DM did not improve prepartum blood profiles or postpartum milk yield or composition; therefore, this type of supplementation was not economical.