|Lupton, Christopher - TEXAS A&M UNIVERSITY|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 28, 2004
Publication Date: August 2, 2004
Citation: Lupton, C.J., Freking, B.A., Leymaster, K.A. 2004. Evaluation of Dorset, Finnsheep, Romanov, Texel and Montadale breeds of sheep: III. Wool characteristics of F1 ewes. Journal of Animal Science. 82:2293-2300. Interpretive Summary: Comparison of sheep breeds provides critical information to guide the appropriate use of breeds in crossbreeding systems. The productivity of crossbred ewes by Dorset, Finnsheep, Romanov, Texel, and Montadale sires and out of Composite and northwestern whiteface dams was evaluated. Wool production and quality were measured as part of the comprehensive evaluation of these sire and dam breeds. In the current wool market, the income from wool produced by the ten types of crossbred ewes would contribute roughly 1 to 5% of overall income from sheep production. Wool value from these breed types is further undermined by the presence of non-white wool in some of the predominantly white fleeces. In this respect, Romanov crosses produced the lowest percentage of white fleeces (63%) in contrast to Dorset crosses (96%). However, superior productivity of Romanov-sired ewes due to greater conception rate, prolificacy, and longevity, far offsets the decreased wool value of fleeces from crossbred Romanov ewes. Broader use of crossbred Romanov ewes would greatly increase the efficiency of commercial sheep production.
Technical Abstract: An experiment was designed to evaluate the effects of five sire breeds (Dorset, Finnsheep, Romanov, Texel, and Montadale), two dam breeds (Composite III (CIII) and northwestern whiteface (WF)), and three shearing seasons (December, February, and April; corresponding to August, October, and December breeding seasons) and their interactions on (inter alia) wool characteristics of F1 ewes. Fleeces were collected and characterized from six two-year-old F1 ewes representing each of the 90 sire breed x dam breed x shearing season x year (3) subclasses. Characteristics measured objectively were grease and clean fleece weights, clean yield, mean fiber diameter and SD, and mean staple length and SD. Visual assessments of fleece color were also made. Data collected on the F1 ewes were analyzed using the mixed model analysis of variance procedure in SAS (version 7.00). The model included fixed effects of year of birth, sire breed, dam breed, shearing season, six two-way interactions, and the three-way interaction of sire breed x dam breed x shearing season. The random effect of individual sire within year of birth x sire breed was also fitted. Texel- and Montadale-sired ewes produced more clean wool (~0.24 kg) than Dorset-, Finnsheep-, and Romanov-sired ewes. Texel-sired ewes produced the coarsest wool (28.7 µm), whereas Romanov-sired ewes produced the finest (24.9 µm) and longest (9.12 cm) fleeces. Ewes from WF dams produced more and finer wool (0.15 kg and 2.7 µm) than ewes from CIII dams. Ewes shorn in December produced more, coarser, and longer wool than those shorn in February and April. The decrease in wool production is consistent with the corresponding increase in conception rate reported previously. Romanov-sired ewes produced the lowest percentage of white fleeces (62.6%), whereas Dorset-sired ewes produced the most white fleeces (96.3%). Estimates of heritability were calculated for grease and clean fleece weights (0.36), percentage clean yield (0.31), average fiber diameter and SD (0.86 and 0.42, respectively), and average staple length and SD (0.49 and 0.00, respectively). Though necessary for a thorough evaluation of these 10 types of crossbred ewes, it is estimated that wool income would only constitute a small portion (1 to 5%) of overall income from sheep of this type.