Effects of anionic salts in a pre-partum dairy ration on calcium metabolism.

C.J Van Dijk,D.C Lourens

doi:10.4102/jsava.v72i2.621

Abstract

The effects of anionic salts in the transition diet on serum and urine calcium at calving and on peripartal health, subsequent milk production and fertility performance were studied in a well-managed, high-producing Friesland dairy herd. Over a period of a year, approximately 21 days before the expected date of calving, 28 pre-partum heifers and 44 multiparous dry cows were randomly allocated within parity to 1 of 2 transition diets, designated control and experimental anionic diets. The anionic diet contained the same quantities of the basic transition ration fed to the control group as well as a standard anionic salt mixture containing 118 g NH4Cl, 36 g (NH4)2SO4 and 68 g MgSO4 (total 222 g) per animal per day. This reduced the DCAD to -11.68 mEq/100 g dietary dry matter compared to +13.57 for the control diet. Blood and urine were randomly sampled from 7 to 8 animals within each category within 3 hours post-partum. Serum calcium (total and ionised) and creatinine, urine calcium and creatinine and the fractional clearance of calcium were assessed. Relevant clinical, milk production, and fertility data were collected. The total serum calcium (2.07 versus 1.60 mmol/l), serum ionised calcium (1.12 vs 1.02 mmol/l), urine calcium (0.92 vs 0.10 mmol/l) and the fractional clearance of calcium (1.88 vs 0.09%) were significantly higher(P <0.01) at calving for multiparous cows fed the anionic diet compared to those fed the control diet. In the primiparous cows there were no significant differences in serum calcium levels. However, the urine calcium (1.07 vs 0.43 mmol/l) and the fractional clearance of calcium was higher (1.75 vs 0.45%) in cows fed the anionic diet (P <0.05 and 0.01 respectively). These results illustrated that there were benefits, although no differences were demonstrated with respect to health, milk production or fertility. The supplementation of diets with anionic salts in the last 2-3 weeks before calving has the potential to significantly improve parturient calcium homeostasis.

Highlights

Dairy cows experience many transitions during their production cycle
The objectives of this study were to study the effects of anionic salts in the transition or close-up dry cow ration on serum and urine calcium levels at calving, and on peripartal health, subsequent milk production and fertility performance in a well-managed, high-producing Friesland dairy herd
The total serum calcium (2.07 versus 1.60 mmol/ ), serum ionised calcium (1.12 vs 1.02 mmol/ ), urine calcium (0.92 vs 0.10 mmol/ ) and the fractional clearance of calcium (1.88 vs 0.09 %) were significantly higher (P

Summary

Introduction

Dairy cows experience many transitions during their production cycle. Feeding the dairy cow during the last 21–28 days of the dry period is a challenge, owing to the unique set of nutritional, physiological and metabolical changes that occur during this period[15,19,28,34]. The signs of an inadequate transition programme are well-known and include cows with a poor appetite after calving, a greater incidence of post-parturient disorders, excessive loss of body condition after caving, variable milk production peaks and persistence and decreased reproductive performance[9,10,19]. APfizer Animal Health, PO Box 783720, Sandton, 2146 South Africa. BDepartment of Production Animal and Community Health, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa.

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