Clean wool colour (CWC) is an important wool price determinant and has been related to suint characteristics, i.e. sudoriparous and sebaceous gland secretions, such as suint percentage and suint K content. In this work heritability, phenotypic and genetic correlations among wool colour and skin traits were examined. The genetic estimates were assessed by Restricted Maximum Likelihood (REML) procedures using average information algorithm (AIREML) in a Corriedale flock. The traits analysed were wool colour traits (CWC), yellow predictive colour (YPC), and Visual Score; suint traits such as suint percentage and potassium and sodium concentrations in suint, and physiological traits such as potassium and sodium concentrations in the skin, including plasma and red blood cells. The objectives of this study were to assess phenotypic and genetic correlations between wool colour and skin traits, and to find the suitability of these traits as indirect selection criteria for clean wool colour. Suint traits were highly genetically correlated to YPC. Suint K, but not suint percentage, was found to have a high genetic correlation with CWC. Skin K, Visual Score, YPC and suint K were amongst the best indirect selection criteria for clean wool colour. However, selection using these traits was expected to reduce CWC from 52% to 49% of that estimated under direct selection.
The mating response and lambing outcome in fifty-three sheep was studied after treatment with intravaginal sponges during October (normal breeding season). Bach pessary carried a dose of 30 mg 'Cronolone' (9a-fluoro-ll/?-hydroxy-17a-acetoxyprogesterone; SC-9880, G. D. Searle) in finely dispersed form and was inserted for 14 days. Half the number of pessaries carried an additional dose of 400 mg progesterone. Breeding was by natural service, using 10 % rams. Ninety per cent of the fifty ewes bred immediately after treatment conceived; the average number of lambs/conception was 1-9. Sheep treated with ' Cronolone'/progesterone pessaries showed a marginal and non-significant advantage over those treated with 'Cronolone'. The application was effective in ensuring the birth of most lambs (87 % of total) within a period of 1 week.
Ninety-eight sheep in three farm flocks were treated in July (period of late anoestrus) with intravaginal sponges impregnated with 30 mg 'Cronolone' (9a-fluoro-ll/Jhydroxy-17a-acetoxy-progesterone; G. D. Searle) or 'Cronolone' plus 400 mg progesterone and incorporating doses of 0-800 fig diethyl stilboestrol. Treatment was for 12 days; a single dose of 500 i.u. PMS (Burroughs Wellcome) was injected at pessary withdrawal. Ten rams bred the ewes at the induced and subsequent heats.Of the ninety-five ewes retaining pessaries, ninety-three (98 %) were bred in the 3 days following treatment. Sixty-three sheep (68-5 %) conceived at the controlled oestrus, producing an average of 1-54 lambs/conception. In the thirty-four ewes failing to conceive at that time, twenty-seven (80%) showed oestrus after one cycle interval; twenty of these (74%) conceived and produced 1-3 lambs/conception. Lambing outcome to services at the controlled oestrus was lowest in sheep treated with 800 fig stilboestrol, but the reduction was not significant.
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