The development of new synthetic materials used in the manufacture of textile fibres has greatly expanded the range of properties able to be delivered by apparel and other weaves and has also exceeded the capabilities of natural fibres such as wool and cotton in these uses. Consequently, producers of natural fibres have sought to improve fibre properties and broaden their property range. For wool, a relatively coarse and weak fibre, this has led to selection for animals which synthesise finer fibres for apparel fabrics and among other features, those which produce highly crimped fibres to improve wool "bulk". In addition, post-farm treatments of the fibre and its surface have recently been used to create wool fibres more suitable for general and sport apparel manufacture. For example, pure wool or blended-wool garments with "easy care" features and with better moisture conduction qualities have recently been produced. Such products provide solutions for the present but are costly to manufacture. If similar properties could be engineered into wool through manipulation of the chemical composition of fibres on-farm, during wool growth, considerable savings in off-farm energy consumption and posttreatment processing costs could be achieved. Transgenesis provides an opportunity to develop wools with different protein compositions and properties that could be an advantage during processing or which might provide novel qualities to the end product. Here we describe experiments to create wool fibres with improved qualities; sheep transgenesis using wool fibre keratin and keratin-associated protein genes mis-expressed in the wool follicle cortex.

Eight flocks of ewes grazing improved pastures which contained oestrogenic clover (Trifolium subterraneum cv. Yarloop) were studied. Two data-sets were available for analysis: Data-set 1-four flocks, three with age-structure unknown. Records on the number of ewes lambing per ewe exposed to the ram (EPJ) and the number of lambs born per ewe exposed to the ram (LBJ) were collected during 1972-75. The repeatability of EPJ and LBJ were estimated within flocks by the regression methods. There was considerable variation between flocks in the values obtained. An analysis of variance was conducted including lambing status (0, 1 or 2 lambs at birth) of the ewes in 1972 as a main effect. Class 1 ewes had a better reproductive performance in subsequent years than either class 0 or class 2 ewes. The effects on flock performance of culling barren ewes were simulated, showing that little improvement in subsequent performance would result. Data-set 2-four flocks, age-structure known. EPJ and LBJ were recorded in 1973 and 1974. The repeatabilities of EPJ and LBJ were estimated within age groups of each flock by regression methods. The results were less variable than in data-set 1. An analysis of variance was conducted, including lambing status (0 or 1 lamb at birth) in 1973 as a main effect. Class 1 ewes had a better reproductive performance in 1974 than class 0 ewes. Simulation of the effects of culling ewes which were barren in 1973 showed that only a small improvement in reproductive performance of ewes in 1974 could be obtained. It was concluded that the culling of barren ewes is unlikely to provide a solution to the low reproduction rate of ewes grazing oestrogenic pastures.

The responses in liveweight, wool weight and survival, to selenium supplementation, were studied in young sheep from weaning to yearling age. The experiment was conducted over three years. In the first year, one sodium selenite supplementation rate was used (total dose 46.5 mg). During the following two years two supplementation rates were administered (total doses 46.5 mg and 93 mg). Mean concentrations of selenium in whole blood in unsupplemented sheep varied from 0.19-0.56 pmol l-l and from 0.20-0.44 pmol l-1 in the two years in which concentrations were measured. Supplementation, which commenced at lamb marking, increased the selenium concentration in sheep at weaning and thereafter. Selenium supplementation improved the break-of-season weight (P < 0.01) and yearling weight (P < 0.01 ) but not weaning weight (0.05 < P < 0.1 ). Hogget fleece weight was improved (P < 0.01 ) and mortality reduced (P < 0.01) by selenium supplementation. There was a treatment x year interaction in mortality rates (P < 0.01 ). There were no significant differences between the two supplementation rates