Fresh and frozen sperm quality was enhanced in bulls fed an organic trace mineral supplement compared to bulls fed a more traditional inorganic mineral supplement.

Mature Angus and Balancer bulls were fed zinc, copper, cobalt and manganese from inorganic and organic sources by University of Arkansas researchers. These minerals are most commonly fed to livestock as inorganic molecules of sulfates or carbonates. More recently, however, organic sources (complexes of a mineral and an amino acid or carbohydrate) are more often being utilized, due to improved bioavailability.

The inorganic diet contained only the test trace minerals from inorganic sources, while the organic diet contained trace minerals from both organic and inorganic mineral sources. The organic portion was supplied by Availa-4® from Zinpro Corporation. All other ration ingredients were identical for the two treatment groups.

Bulls were fed the supplemental trace minerals from mid May to September. Because sperm production in bulls requires 60 days, weekly semen collection began in mid July and continued for nine weeks via electro-ejaculation. Samples were evaluated for motility, either fresh or following a freeze-thaw procedure, by computer-assisted sperm analysis.

Fresh-semen sperm motility was increased from 55.2% to 69.1% in the bulls fed the organic trace mineral supplement. Frozen-semen sperm motility also increased at zero and two hours post-thawing.