Melatonin as a furring enhancer: effect on growth rate, feed consumption and reproduction in silver fox. M. L. Connor, Department of Animal Science, Nova Scotia Agricultural College, Truro, Nova Scotia, Canada
Biology, Pathology & Genetics of Fur Bearing Animals. IVth International Scientific Congress in Fur Animal Production. p 437-443. 1988.
Two trials were conducted in separate years to investigate the influence of melatonin and low illumination on fur growth, feed consumption, animal size, pelt quality and reproduction in silver fox. In trial 1, 60 silver fox pups were allotted to one of 3 treatments in early July: 12 mg melatonin capsule S.C.; housed under very low light conditions (<45 lux); or housed under normal pelter shed conditions (control). For trial 2, 90 silver fox pups, in 3 equal groups, were assigned to receive either 12 mg, 8 mg or 0 mg melatonin. Implanted animals grew and furred out more quickly reaching full prime 4-6 weeks before controls. Animals under low light did not significantly outperform the controls. Final size, pelt quality and guard hair length were similar between implanted pups and controls in trial 1. More implanted animals were off color at pelting in trial 2 (4/25, 9/25, and 2/25 for 12 mg, 8 mg and 0 mg respectively). As well, guard hair length was shorter on implanted pets in trial 2, however, this was not reflected in negative auction results. Feed consumption was similar between treatments to 23 weeks of age (trial 2) but was greater for controls from 23 weeks to pelting. Testicular development was advanced in implanted males, and semen could be collected by mid-December (trial 2) approximately one month before controls. Signs of proestrus were evident by mid-December (trial 2), 3 of 8 vixens were mated during the normal breeding season and whelped litters of 1, 6 and 7 pups respectively. Two other vixens necropsied had luteal tissue and functional mammary glands indicative of ovulation and pseudopregnancy.