Growth and survival of crossbred progeny of Dorset and Dorset X Merino rams.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. 16 DIET SELECTION BY GOATS AND SHEEP GRAZING ANNUAL PASTURES N.K. GURUNG*, J.H.G. HOLMES*, B.A. McGREGOR** and M.J. WATSON** The diet selected by 4 oesophageal fistulated goats and 4 oesophagael fistulated sheep were compared when grazing annual pastures at Werribee between 26 March and 4 April 1985 (Period 1) and 20 May and 23 May 1985 (Period 2). During Period 1 only 7% green pasture was on offer compared to 47% during Period 2. Table 1 shows chemical composition and in vitro digestibilities of the extrusa. It is concluded from this study that sheep grazing annual pastures after the 'autumn break' select diets of higher nutritive value than goats. * School of Agric-and Forestry, University of Melbourne, Parkville, 3052, Vic. ** Dept-of Agric. and Rural Affairs,Animal Research Institute, Werribee, 3030,Vic. GROWTH OF CROSSBRED PROGENY OF DORSET AND DORSET X MERINO RAMS D.G. HALL* and N.M. FOGARTY* As part of the development of a new dam breed for lamb production (Fogarty) 1984), growth of crossbred progeny of Poll Dorset (PD) and Dorset x Merino Fl (DM) rams were compared. Mature Border Leicester x Merino ewes were joined to either five PD or five DM rams for three weeks from 27 April 1983 at Temora AgricRams were castrated at six weeks of age and lambs ultural Research Station. (149) weaned at 12 weeks with the heaviest half being slaughtered at 18 weeks Lamb birth weight, growth rate, carcase weight and the remainder at 23 weeks. and fat depth were analysed by generalized linear models to assess the effects of sire group, sex and birth/rearing status. Progeny of DM rams were lighter at birth than progeny of PD rams (4.3 v 4.5 kg, P<.O5). There were no differences between the sire groups for any other growth or carcase trait analysed. Single lambs were . 5 kg heavier (P<.Ol) than twin lambs and ram lambs were .3 kg heavier (P<.Ol) than ewe lambs at birth. Lamb growth rate to weaning was higher for wethers than ewes (223 v 199 g/d, P<.Ol) and singles than twins (247 v 175 g/d) with twin born/single reared intermediate (211 g/d, P<.Ol). Post weaning, twins grew faster than singles (190 v 164 g/d P <.05) to fully compensate their preweaning disadvantage by slaughter at 23 weeks. Subcutaneous fat depth at the 'C' position was .5 mm lower for wethers than ewes (P<.O5) despite having .5 kg heavier carcases. FOGARTY, N.M. (1984). Proc. Aust. Soc. Anim. Prod. 15:66. - * Department of Agriculture, Agricultural Research Station, Cowra, N.S.W. 2794 413