Effect of Different Levels of Copper and Molybdenum Supplements on Performance, Nutrient Digestibility, and Follicle Characteristics in Cashmere Goats

Abstract

A 2 × 3 factorial arrangement of treatments was used to investigate the effects of different levels of copper (Cu, 0, 19, and 38mg/kg, dry matter (DM)) and molybdenum (Mo, 0 and 5mg/kg, DM) supplements and an interaction of these two factors on growth performance, nutrient digestibility, and cashmere and follicle characteristics in cashmere goats. Thirty-six Liaoning cashmere goats (approximately 1.5years of age; 27.53 ± 1.38kg of body weight) were assigned randomly to one of six treatments and fed with Chinese wildrye- and alfalfa hay-based treatment diets (the basal diet contained 4.72mg Cu/kg, 1.65mg Mo/kg, and 0.21% S.). Body weight was measured on two consecutive days at the start and the end of the 70-day experimental period. On day30, the metabolism trial was conducted to study the effects of dietary Cu and Mo on nutrient digestibility. The cashmere and skin samples were collected on day70. Copper supplementation increased (P < 0.05) growth performance and fiber digestion, but there were no differences (P > 0.05) between Cu-supplemented groups. Addition of 19mg Cu/kg DM increased (P < 0.05) cashmere growth length or growth rate by increasing the number of active secondary follicles. Molybdenum supplementation decreased (P < 0.05) growth, but did not affect (P > 0.05) nutrient digestion, cashmere, and follicle characteristics. There is a tendency or significant interaction effect of Cu and Mo on growth performance (P = 0.057), cashmere growth (P = 0.076), or diameter (P < 0.05) which might be accomplished by changing the number of secondary follicle and active secondary follicle, and secondary to primary follicle ratio. In conclusion, the optimal supplemental Cu level for Liaoning cashmere goats fed with the basal diet was 19mg/kg DM (the total dietary Cu level of 23.72mg/kg DM), while 38mg Cu/kg DM supplementation was found to be needed when 5mg Mo/kg was added in the basal diet during the cashmere growing period.