2010-Alvarez-_et_al - Introduction of meat sheep breeds in...

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M. Álvarez, R. M. Rodríguez Iglesias, J. García Vinent, H. Giorgetti and M. Baselga and survival Introduction of meat sheep breeds in extensive systems of Patagonia: Lamb growth 2009-12-18T10:46:15-08:00; 2010, 88:1256-1266.doi: 10.2527/jas.2009-2239 originally published online J ANIM SCI http://jas.fass.org/content/88/4/1256 the World Wide Web at: The online version of this article, along with updated information and services, is located on www.asas.org by guest on May 22, 2011 jas.fass.org Downloaded from
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ABSTRACT: Genotype effects on lamb growth, sur- vival, and commercial finishing were estimated in a 5-yr study aimed at assessing potential benefits from introducing meat breeds into extensive sheep systems of northeastern Patagonia. Five ram [Corriedale: CO; Border Leicester: BL; Île de France: IF; Texel: TX; and synthetic CRIII (25% Merino, 37.5% IF, 37.5% TX)] and 5 dam (CO; synthetic CRIII; BLCO: BL × CO; IFCO: IF × CO; and TXCO: TX × CO) genotypes were represented in the study. Data were collected from 1,426 born and 1,258 weaned lambs of 9 resulting geno- types (CO × CO, BL × CO, IF × CO, TX × CO, CRIII × CO, CRIII × BLCO, CRIII × IFCO, CRIII × TXCO, and CRIII × CRIII). Birth weight was re- corded on all lambs; subsequently, BW and BCS (scale 1 to 5) were recorded at regular intervals until weaning. Body weights were adjusted to 60 and 90 (weaning) d of age, and ADG were calculated from the adjusted BW for the periods 0 to 60 d and 60 to 90 d; BCS was adjusted to 90 d. Survival to weaning and percentage of lambs reaching commercial finishing (BW ≥ 23 kg and BCS ≥ 2.5 points) were also recorded. Significant ( P < 0.05) genotype × litter size interactions were detected for birth weight and ADG 60 to 90 d. With the excep- tion of CRIII × CO, crossbred and synthetic genotypes presented greater ( P < 0.05) ADG 0 to 60 d and BW at 60 and 90 d than CO × CO lambs. Second cross lambs reared as singles presented greater ADG 60 to 90 d ( P < 0.05) than BL × CO, TX × CO, and CRIII × CO, but less ( P < 0.05) ADG 60 to 90 d, and no differences were observed for twins. The IF × CO, CRIII × BLCO, CRIII × IFCO, and CRIII × CRIII genotypes showed greater BCS at 90 d ( P < 0.05) than CO × CO. The probability of greater commercial finishing for cross- bred and synthetic genotypes relative to CO × CO was at least 79%. Probabilities of greater survival to wean- ing in CO × CO and CRIII × BLCO lambs relative to IF × CO, TX × CO, CRIII × CO, and CRIII × CRIII lambs were greater than 81%. Results indicate signif- icant improvements in lamb BW and saleable lambs from the introduction of meat genotypes. Among the terminal sire breeds evaluated, BL and IF would pro- duce the greatest impact. Differential nutritional man- agement of pregnant ewes carrying twins and of twin lambs beyond 60 d should be implemented to mitigate litter size × genotype interactions constraining growth potential benefits, which may be critical for northeast- ern Patagonia conditions.
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This note was uploaded on 01/26/2012 for the course ECON 2272 taught by Professor Gay during the Spring '08 term at Birmingham-Southern College.

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2010-Alvarez-_et_al - Introduction of meat sheep breeds in...

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