Prediction of wool fibre diameter from protein and metabolisable energy digestibility coefficients in crossbred sheep

Malau-Aduli, A.E.O., Walker, R.E., and Bignell, C.W. (2009) Prediction of wool fibre diameter from protein and metabolisable energy digestibility coefficients in crossbred sheep. Journal of Animal Science, 87 (E-Suppl 2). 519. p. 498.

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Abstract

Our objective in this study was to investigate the interactions between sire breed and supplement on digestibility and to ascertain its accuracy in predicting wool fibre diameter. Forty first-cross Merino weaner sheep sired by Texel, Coopworth, White Suffolk, East-Friesian and Dorset sires with initial BW range of 22.9 and 31.3 kg (average of 26.8 ± 3.2 kg) were randomly assigned to four treatment groups in a 5 × 2 × 2 × 2 factorial experimental design representing 5 sire breeds, 2 supplementary feeds (canola and lupins), 2 feeding levels (1 and 2% of bodyweight) and 2 sexes (ewes and wethers). The feeding trial lasted for six weeks with an initial 3-week adjustment period and the last 7 days for faecal collection. Factorial ANOVA with orthogonal contrasts in SAS was used for statistical analysis to test for the interactions between sire breed and supplement on digestibility and wool fibre diameter. Our results demonstrated that sire breed × level of feeding interactions significantly influenced digestibility (P<0.01) whereby Coopworth-sired sheep supplemented at 1% of their body weight recorded the highest ME and N digestibility of 54% and 67% compared to 42% and 62% respectively, in their counterparts fed at 2% of body weight. There was a highly significant (P<0.01) effect of type of supplement x level of feeding interaction on wool fibre diameter at the end of the trial because sheep fed canola supplements at 1% of body weight had finer wool (22.1 microns) than their 2%-fed counterparts (25.4 microns). Regression of wool fibre diameter on digestibility revealed very poor prediction accuracy (R2 = 0.0087-0.169). We concluded that sire breed variation in digestibility is unlikely to be a useful predictor of genetic merit for wool fibre diameter in first cross sheep under the same management.

Item ID: 53167
Item Type: Article (Abstract)
ISSN: 1525-3163
Keywords: digestibility, wool, fibre diameter
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Date Deposited: 17 Jul 2018 02:31
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070201 Animal Breeding @ 35%
07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070204 Animal Nutrition @ 35%
06 BIOLOGICAL SCIENCES > 0604 Genetics > 060499 Genetics not elsewhere classified @ 30%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8303 Livestock Raising > 830311 Sheep - Wool @ 100%
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