Ninety heifers sired by Charolais or Red Poll bulls were utilised in two trials involving ovariectomy, ovarian tissue transplants (autografts) andlor an anabolic implant. In trial 1, four treatments were imposed upon 60 heifers: (1) autograft, (2) autograft plus Synovex‐H® implant, (3) vaginal ovariectomy plus implant, and (4) intact plus implant. Three replications of five heifers per treatment were fed a finishing diet until heifers weighed approximately 432 kg. Autografed‐implanted heifers exhibited a greater average daily gain than non‐implanted autografted heifers (P < 0.05). No treatment effects were detected for feed eficiency or dressing percentage. Carcasses from autografted heifers merited higher marbling scores and USDA quality grades than did those of ovariectomised‐implanted heifers. Fat thickness tended to be greater for autografted heifers than for heifers in the implant treatment groups (P <0.l0). Non‐implanted autografted heifers had smaller ribeye areas, more kidney, pelvic and heart fat, and higher numerical USDA yield grades. Shear force values and taste panel scores for meat favoured non‐implanted autografted heifers. In trial 2, 30 heifers were autografted, ovariectomised via high lumbar laparotomy, or left as intact controls. Heifers in trial 2 were fed a finishing diet until heifers reached 1.2 ern average backfat thickness. Intact heifers tended to gain weight more rapidly than did ovariectomised heifers. Ovarian cell types were detected at the graft sites of only four of the 10 autografted heifers upon post‐mortem histological examination. Very low levels of oestrogen were present in the fluid aspirated from three of the apparently successful grafts. However, growth rate was not superior for these three heifers.
- carcass merit