title: The effects of spaying and anabolic implants on the average daily weight gain of heifers on pasture.
abstract: Two studies were carried out to determine the effects of spaying and implanting on the growth of heifers and compare Ralgro and Synovex-S for spayed heifers. In the first study, 121 crossbred heifers were randomly allocated to four groups: intact and no implant; intact and progesterone and estradiol benzoate (Synovex-S); spayed and no implant; and spayed and Synovex-S. The average daily gain (ADG) and body weight (BW) data were analyzed as a 2 x 2 factorial experiment with a pasture effect which was considered as a block. Based on ADG for days 0-120, the response to implanting was 17.6% for spayed heifers and 1.8% for intact heifers. In the second study, 31 spayed heifers implanted with zeranol (Ralgro) were compared with 30 spayed heifers implanted with Synovex-S. The data were analyzed as a one-way analysis of variance. The ADG for spayed heifers on Ralgro did not differ significantly (p>0.05) from those implanted with Synovex-S over a period of 92 days, suggesting that both implants produce similar growth responses.
authors.forename: D R
authors.initials: DR
authors.lastname: Zobell
authors.forename: L A
authors.initials: LA
authors.lastname: Goonewardene
authors.forename: C
authors.initials: C
authors.lastname: Bertagnolli
authors.forename: K
authors.initials: K
authors.lastname: Ziegler