Oral vitamin a supplementation to debilitated cattle during Sahelian dry seasons

Abstract

Ruminant vitamin A deficiency occurs annually in the pastoral zone of the Sahel in West Africa; Twareg herders recognize clinical signs of night blidness in their cattle during the latter half of the annual 9-month dry season. If not treated, cattle become completely blind, are unable to graze and drink with the nomadic herd and are abandoned to die. Twareg people depend upon bovine milk for their source of vitamin A, and therefore nyctalopia is noted among people subsequent to the appearance of night blindness in their cattle. The objective of this study was to assess the efficacy of three vitamin A supplements (powder, bolus and injectable forms) in the treatment of bovine nyctalopia, and to attempt to raise milk vitamin A concentrations. β-carotene and vitamin A concentrations were measured in bovine milk and plasma before and after vitamin A supplementation to relate clinical signs of deficiency with the physiological concentrations and efficacy of each supplement. In the short-term study, the powder vitamin A product was superior to the bolus product in ease of administration; however, both oral products resulted in significantly increased milk vitamin A concentrations for 3 days post-treatment, while the traditional injectable product did not increase milk vitamin A level until Day 3 post-treatment. In the long-term study, oral vitamin A supplementation did not significantly increase plasma vitamin A above deficiency levels, although herder testimonials indicated both bolus and powder oral products were efficacious in alleviating bovine nyctalopia within a day of treatment and preventing recurrence for approximately 2 months.