caa a22 4500 388060832 CHVBK 20180307125120.0 cr unu---uuuuu 161130e199804 xx s 000 0 eng 10.1017/S1357729800009504 doi S1357729800009504 pii (NATIONALLICENCE)cambridge-10.1017/S1357729800009504 Genotype differences in responses of growth and carcass characteristics to the intrauterine cohabitant phenomenon in twin lambs [Elektronische Daten] The preweaning growth and carcass characteristics offour lamb genotypes were analysed for variation attributable to the intrauterine cohabitant (IUC) phenomenon, where within-sex variation is attributed to the sex of a twin's womb-mate. The four genotypes resulted from the following matings: Poll Dorset rams × Merino ewes, Poll Dorset rams × (Border Leicester × Merino) ewes, Texel rams × Merino ewes and Texel rams × (Border Leicester × Merino) ewes. Four hundred and twenty twin lambs participated in the preweaning study and of these, 209 were slaughtered to generate carcass data. Some of these genotypes displayed within-sex variation in weaning weight and fat score, preweaning average daily gain, skin-fold thickness, carcass fatness and eye muscle dimensions attributable to the IUC phenomenon. Genotypic differences in the responses of lambs to the IUC phenomenon were also observed. The IUC phenomenon appears to involve prenatal programming, an hypothesis that attributes postnatal characteristics to events during differentiation. The IUC phenomenon is analogous to the intrauterine position phenomenon in fecund mammals, where variations in prenatal steroid concentrations programme for permanent alterations in postnatal reproductive characteristics. The growth responses reported in this paper provide evidence of variation due to prenatal programming. While the magnitude of the responses to the IUC phenomenon were not large, the data presented indicate that under field conditions, the magnitude of growth responses to the IUC phenomenon may be as great as those observed between breeds. If so, further examination of the role that an animal's IUC may have on its subsequent performance could aid the development of more sensitive indices for breed evaluation and progeny selection. Copyright © British Society of Animal Science 1998 carcass composition nationallicence genotypes nationallicence growth nationallicence lambs nationallicence prenatal programming nationallicence Gill J. W. Faculty of Agriculture, Forestry and Horticulture, University of Melbourne, Parkville, VIC 3052, Australia Hosking B. J. Faculty of Agriculture, Forestry and Horticulture, University of Melbourne, Parkville, VIC 3052, Australia Holst P. J. NSW Agriculture, Agricultural Research Station, Cowra, NSW 2794, Australia Fogarty N. M. NSW Agriculture, Agricultural Research and Veterninary Centre, Orange, NSW 2800, Australia Hopkins D. L. NSW Agriculture, Agricultural Research Station, Cowra, NSW 2794, Australia Egan A. R. Faculty of Agriculture, Forestry and Horticulture, University of Melbourne, Parkville, VIC 3052, Australia Animal Science Cambridge University Press 66/2(1998-04), 375-382 1357-7298 66:2<375 1998 66 ASC https://doi.org/10.1017/S1357729800009504 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S1357729800009504 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Gill J. W. Faculty of Agriculture, Forestry and Horticulture, University of Melbourne, Parkville, VIC 3052, Australia NATIONALLICENCE 700 1- Hosking B. J. Faculty of Agriculture, Forestry and Horticulture, University of Melbourne, Parkville, VIC 3052, Australia NATIONALLICENCE 700 1- Holst P. J. NSW Agriculture, Agricultural Research Station, Cowra, NSW 2794, Australia NATIONALLICENCE 700 1- Fogarty N. M. NSW Agriculture, Agricultural Research and Veterninary Centre, Orange, NSW 2800, Australia NATIONALLICENCE 700 1- Hopkins D. L. NSW Agriculture, Agricultural Research Station, Cowra, NSW 2794, Australia NATIONALLICENCE 700 1- Egan A. R. Faculty of Agriculture, Forestry and Horticulture, University of Melbourne, Parkville, VIC 3052, Australia NATIONALLICENCE 773 0- Animal Science Cambridge University Press 66/2(1998-04), 375-382 1357-7298 66:2<375 1998 66 ASC CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge