An investigation of the safety of oral calcium formate in dairy cows using clinical, biochemical and histopathological parameters

Abstract

AIM: To investigate the safety of orally administered calcium formate in dairy cows fed adequate amounts of good quality pasture.

METHODS: Twelve mixed-age pasture-fed lactating dairy cows were randomly allocated to three groups (n=4 cows/ group). Group 1 served as untreated controls. Group 2 was treated orally with 400 ml of 13.4% (w/w) calcium as calcium chloride gel, four times at approximately 12-h intervals. Group 3 was treated orally with 350 ml of 11.4 % (w/w) calcium as a 48.6% aqueous suspension of calcium formate, four times at approximately 12-h intervals. Cows grazed good quality autumn ryegrass and white clover pasture throughout the trial. All cows were examined clinically each evening and a blood sample collected. Cows were slaughtered 75 h after the last treatment and viscera examined visually for lesions. Samples from the mid-fundic area of the abomasum of each cow were collected for histopathological examination. Blood samples collected pre- and 90-h post-first treatment were analysed for serum haptoglobin and pepsinogen concentrations.

RESULTS: No evidence of abnormality was detected by observation or clinical examination in any of the trial cows. Serum haptoglobin concentrations were basal for all groups pre-treatment and remained basal for Groups 1 and 3 post-treatment, but were elevated post-treatment for Group 2 (p=0.016). No differences in serum pepsinogen concentrations were detected between sampling times or treatment groups. One cow from Group 2 had several small (5 mm) abomasal ulcers present at necropsy. Another cow from the same group had histopathology suggestive of thrombosis and re-endothelialisation.

CONCLUSIONS: Oral administration of calcium formate (350 ml of 48.6% aqueous suspension) administered on four occasions at 12-h intervals had no adverse effects on the four cows examined, and as such is considered a safe form of calcium supplementation in adult dairy cows.

KEY WORDS:

• Hypocalcaemia
• calcium formate
• calcium chloride
• cattle
• haptoglobin
• pepsinogen