Hipocalcemia

FULL PAPER Internal Medicine

Preventive Effect of Mildly Altering Dietary Cation-Anion Difference on Milk Fever
in Dairy Cows
Naotoshi KUROSAKI1,2), Osamu YAMATO1)*, Fuminobu MORI2), Seiichi IMOTO3) and Yoshimitsu MAEDE1)
1)
Laboratory of Internal Medicine, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido
University, Kita-18 Nishi-9, Kita-ku,Sapporo 060–0818, 2)Total Herd Management Service, Ltd., 22-banchi Asahi-machi, Kamishunbetsu,
Bekkai-chio, Notsuke-gun 088–2722 and 3)Toxicology Consultant, 2-jo 8-choume, Hiragishi, Toyohira-ku, Sapporo 062–0932, Japan

(Received 5 September 2006/Accepted 1 November 2006)
ABSTRACT.

In the present study, we examined whether mildly altering dietary cation-anion difference (DCAD) contributesto the prevention of milk fever in dairy cows. Thirty multiparous cows and ten primiparous cows (heifer group) were used in this study and the multiparous cows were randomly divided into three groups of ten animals each (anion, non-anion and control groups). The cows in the anion
group were given supplemental salts that slightly lowered DCAD. These salts consisted of 115 g of CaCO3, 42 g ofCaHPO4, 65 g of
MgSO4•7H2O and 80 g of CaCl2•2H2O as a daily dose for each cow, using a catheter from 21 days before the expected date of parturition
until parturition. The cows in the non-anion group were given only the same Ca, Mg and ip supplement but no sulfate and chloride salts
as that in the anion group. The cows in the control and heifer groups were not given any additional supplement. Theincidence of hypocalcemia in the anion group decreased to approximately half of those in the non-anion and control groups, while the heifer group did not
develop hypocalcemia at all. In addition, the number of days spent for the treatment of hypocalcemia and the number of drug bottles
(calcium borogluconate solution) used for the treatment decreased to less than half in the anion group comparedwith those in the nonanion and control groups. At parturition, the serum Ca concentration in the control (6.2 ± 1.9 mg/dl, mean ± standard deviation) and
non-anion groups (6.4 ± 1.7 mg/dl) were significantly lower than that in the heifer group (8.3 ± 0.4 mg/dl), and the level in the anion
group was intermediate (7.3 ± 1.3 mg/dl). The change in ionized Ca concentration was almost the same as thatin serum Ca concentration, but only the concentration in the anion group tended to increase slightly from a week before parturition and was significantly higher
than that in all other groups three days before parturition. Urinary pH in the anion group was maintained at a mildly acidic level (6.8–
7.0) for the last two weeks before parturition, compared with those in the control (7.3–7.5) andnon-anion groups (7.9–8.1), and similar
to that in the heifer group (6.3–7.3). The urinary Ca excretion was the highest in the anion group among all groups during the prepartum
period. There were no specific changes in the excretion of parathyroid hormone and 1,25-dihydroxyvitamin D in all groups of multiparous cows while the levels of these hormones remained low in the heifer group throughout theexperimental period. The data in the
present study indicates that the administration of anion salts that slightly lowered DCAD in the preparum period was effective for preventing milk fever in multiparous cows. Safe and mild metabolic acidosis induced by the anion salts could be evaluated by urinary pH
(6.8–7.0), and might increase the responsiveness to Ca requirement at parturition through somecomplex mechanisms unrelated to the
excretion of Ca-related hormones. In addition, it was clarified that primiparous cows have a high potential to respond to sudden Ca
demand unrelated to hormone excretion, and their Ca metabolism was in some respects similar to that in multiparous cows fed anion
salts. Therefore, manipulating mildly DCAD is expected to be an effective, safe and natural...