The commercial feasibility of running winter born cryptorchid lambs.

Abstract

Proc. Aust. Soc, Anim. Prod. Vol. 18 THE COMMERCIAL FEASIBILITY OF RUNNING WINTER-BORN CRYPTORCHID LAMBS W.J. JACKSON*, D.L. HOPKINS* and T. FUMO* In recent years, consumer preferences have shifted towards leaner lamb (Hopkins and Congram 1985) and various strategies have been investigated to change the One potential method is the use of level of fat in lamb carcasses. cryptorchidism. Previous work (Lee 1986) has shown that cryptorchids are leaner than wethers and grow faster under intensive conditions. However, there is limited data on the growth of cryptorchids versus wethers under grazing conditions in southern Australia. To establish the potential benefits of cryptorchids under grazing conditions a trial was established on a private property in northern Tasmania. The lambs were sired by Suffolk8 from Comeback ewes and were born in late July 1988. Fifty-four male lambs aged between four and six weeks were randomly selected. One group was made cryptorchids (Hudson et al. 1968) and the other wethers at Live weight, hot carcass weight and hot GR marking using elastrator rings. (total tissue thickness at the 12th rib 110 mm from the midline) were recorded The testicles of the cryptorchids weighed on average at slaughter (Table 1). (A 8-e.) 95.5 + 4.6 grams and had a range of 61-150 g. Table 1 Mean (+ s-e.) final live weight, growth slaughter, hot GR and hot carcass weight rate from marking to The final live weight was obtained prior to slaughter 146 days after marking. Both growth rate to slaughter and final live weight were significantly higher for the cryptorchids. However, the superiority of the cryptorchids was not reflected in terms of carcass weight there being no significant difference between the two groups. A benefit in terms of carcass weight may not be realized unless heavier lambs than those in this trial are produced. The cryptorchids were not significantly leaner than the wethers but according to previous work a significant difference would be expected in carcass fatness between wethers and cryptorchids as live weight increased (Lee 1986). It is apparent from this trial that cryptorchidism did not show benefits in terms of carcass weight and leanness. However, other work has indicated it does have potential for the production of heavy lean carcasses for speciality markets. As a result, we recommend producers who contemplate adopting the practice carefully consider its applicability to their lamb production system. HOPKINS, A-F. and CONGRAM, I.D. (1985). Livestock Meat Authority of Queensland Research Report No. 18. HUDSON, L-W., GLIMP, H-A., WOOLFOLK, P-G., KEMP, J.D. and REESE, 2.X. (1968). J. Anim. Sci. 27: 45. LEE, G.J. (1986). Aust. J. Exp. Agric. 26: 153. PROBERT, A-D. and DAVIES, A.S. (1986). Proc. N.Z. Soc. Anim. Prod. 46:55. * Department of Primary Industry, P.0. 180, Kingsmeadows, Tas. 7249. 497