The Effects of Superovulation Prior to Mating and Zinc Supplementation on Milk Yields in Etawah-Grade Does

Abstract

Thirty six Etawah-grade does (BW ranged from 20.4 to 44.2 kg and age ranged from 2.5 to 7 years) were used to study the effects of superovulation prior to mating and zinc supplementation on milk yields. The experimental does were assigned into a randomized block design with a 2 x 3 factorial arrangement. The first factor was PMSG (pregnant mare serum gonadotrophin) injection with 2 levels (0 IU/kg BW [nonsuperovulation–NSO] and 15 IU/kg BW [Superovulation–SO]). The second factor was zinc concentration in the diet with 3 levels (40 mg/kg DM [Z-40], 60 mg/kg DM [Z-60], and 80 mg/kg DM [Z-80]). Intravaginal sponge (60 mg medroxyprogesterone acetate) was applied for 14 days to synchronize estrus cycle. Twenty four  hours prior to sponge removal, PMSG was injected  to  stimulate superovulation. After  sponge removal,  5 experimental does  were mixed with 1 buck for natural mating. During  pregnancy  the experimental does were fed and  raised in   individual stables. Udder volume  was measured every other week from weeks 12 to 21 of  pregnancy.  During lactation  (one week to  5 months post partum) kids were separated from the does, and   milk was harvested by hand milking. Milk samples were taken every other week for determination of milk quality. The results  indicated that  superovulation increased udder differential growth  by 80% (822.85 vs 1481.25 cm³/head), milk yield by  32% (567.14 vs 746.52 g/head/day).  Zinc concentration  increased udder differential growth and milk yield. Milk productions for does receiving 40, 60 and 80 mg/kg DM were 565.68, 737.88 and 666.92 g/day, respectively.It was concluded that  superovulation and zinc supplementation  increased milk  yield in Etawah Grade does. (Animal Production 6(2): 86-94 (2004)

 

Key Words:  Superovulation, Zinc, Milk  Yield, Etawah-Grade