Evaluation of melatonin and bromocryptine administration in Spanish goats: II. Effect on seasonal cashmere growth, yield and fiber characteristics of does

Abstract

Manipulation of spring breeding in Spanish goats could improve reproductive efficiency, kidding rate and cashmere production. Spanish female goats (15 does and 65 doelings) were used to determine the effects of melatonin treatment on cashmere fiber growth rate, length and characteristics during spring breeding. Treatments were as follows: control (C); melatonin implant (MI) and with a bromocryptine (225 mg) implant (MIB); and oral administration of 3 mg per day of melatonin (MO) or with bromocryptine (MOB). Cashmere growth rate was monitored by monthly clipping of fiber in a 10 cm ×10 cm patch on the mid-side of goats from February 1999 to January 2000. Mean daily clean fiber growth rate (mg per day) was greater ( P<0.05) for melatonin-treated groups compared with C in April (42, 76, 72, 75 and 65 mg per day) and May (37, 64, 74, 58 and 58 mg per day for C, MI, MIB, MO and MOB, respectively). Overall 12-month period fiber growth in patches was 12.5, 15.9, 15.3, 13.1 and 12.9 g for C, MI, MIB, MO and MOB, respectively, being greater ( P<0.05) for MI and MIB than for other groups. Cashmere fiber diameter was greater ( P<0.05) for MI, MIB, MO and MOB as compared with C (17, 19, 19, 18 and 18 μ) during the spring. Fiber diameter of C was lowest ( P<0.05) among treatments (17, 19, 19, 18, and 19 μm for C, MI, MIB, MO and MOB, respectively) during summer. In summary, these results suggest that melatonin given orally or in a slow release implant for out of season breeding in the spring extends the cashmere growth cycle, which can increase cashmere production by Spanish goats.