Abstract :
Thirty-six 2.5-year-old wether Inner Mongolian White Cashmere Goats (IMWG)
(BW= 42.7±3.44 kg) were used to determine the effects of dietary copper (Cu) concentration
on growth performance, nutrient digestibility and fiber characteristics during the
cashmere slow-growing period. Wethers were stratified by weight and randomly assigned
to four dietary treatments, which included a control diet containing 5.60mgCu/kg DM, the
control diet supplied, respectively, with 10, 20 and 30mgCu/kg DM (total dietary Cu level
of 5.60, 15.6, 25.6 and 35.6 mg/kg DM). The experiment lasted 50 days including a 10-day
preliminary trial and 10-day metabolism trial. Average daily feed intake (ADFI) did not differ
among treatment groups (P > 0.05), except that the supplement providing 30mgCu/kg
DM decreased average daily gain and gain efficiency (P < 0.05). Copper supplementation
had no influence on digestibility of DM, CP and ADF (P > 0.05), however, NDF digestibility of
the treatment group supplemented with 30mgCu/kgDMwas lower compared with that of
other groups (P < 0.05). Length and growth rate of cashmere fiber were higher in the treatment
group supplemented with 20mgCu/kg DM compared with other groups (P < 0.05),
but cashmere diameter was not affected by Cu supplementation (P > 0.05). In conclusion,
supplementation of Cu at the levels of 10, 20 and 30 mg/kg DM to the basal diet containing
5.60mgCu/kg DM had no influence on ADFI or nutrient digestibility of DM, CP and
ADF in cashmere goats, while 30mgCu/kg DM supplementation had a negative effect on
growth performance and NDF digestibility. However, 20mgCu/kg DM supplementation of
the basal diet enhanced cashmere growth. Hence, the appropriate supplemental level during
the cashmere slow-growing period is deemed to be 20mgCu/kg DM (total dietary Cu
level of 25.6 mg/kg DM).
