The effects of melatonin treatment on wool production and hair follicle cycle in angora rabbits

The aims of this study were to examine the effect of melatonin treatment on (1) the quantity of wool production and fibre quality traits, (2) feed consumption and body weight and (3) hair follicle activity in the German angora rabbits. The study involved 106 male and female angora rabbits (raised under natural photoperiod), between the initial ages of 200-210 days. Half of the stock was treated with melatonin (36 mg per rabbit) either in May prior to the summer solstice, or in July subsequent to the solstice. Other animals served as untreated controls. In May two methods of wool harvesting: defleecing or shearing, were tested, while in July two different intervals between wool harvests, 98 and 80 days, were compared. Skin samples were taken from May onwards six times during the experimental period. Melatonin treatment increased significantly total wool production (by 17.7%, P < 0.01), weight of first grade wool (by 14.1%, P < 0.01), fibre length (by 5.6%, P < 0.001), wool production per day (by 17.3%, P < 0.01) and per kg of live weight (by 14.6%, P < 0.05). The melatonin treatment also led to a significant increase in feed consumption and body weight during the first weeks following melatonin treatment. Melatonin treatment did not exert any significant effect on the content of the different fibre types, or on bristle dimensions (area and diameter), but resulted in a 32% (P < 0.001) increase in the number of active follicles (lateral primaries and secondaries) per hair follicle group. The date of treatment had a significant influence on the quantity of first grade wool with higher production observed only when animals are treated in July. The treatment proved to be more effective in the defleeced rabbits than in the shorn ones.