الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Data were studied on 139 Ossiml, 295 Rahmani, and 305 crossbred lambs born in consecutive years from 1991 to 1992 from Sakha, Serw, and Sids stations of Ministry of Agncutture under an accelerated lambing system of3 lambing per 2 years.
The traits studied were (length of lamb, height oh lamb, Circumference
of thorax, length of !ail, upper Circumference of tail, largest point of circumference of tail, lower circumference of tail, thickness of tail and principal component ) and tllese traits were measured at birth, 112, 1, 2, 4, and 6 months.
The fixed effects studied were genotypes, type of birth, sex, age of dam, and season of birth. Type of birth have significant effects on all of the nine traits studied. Genotype have significant effects only on thickness of tall, upper circumference of tail, and largest point of circumference of tail at 2, 4, and 6 months. Other fixed effects have non significant effects on all traits.
Heritabilities were obtained from paternal half-sib correlations and performed within genotypes. Heritability eatimats ranged from medium to high for all traits.
Principal component analyses was used to characterize and describe
mass of tail from tail measurements (length oflail, upper circumference of tail, largest po1nt of circumference of tail, and thickness of tail) at various ages intervals. The first pnnciple component accounted lor >60% of the variation in the dependency structure, and provided a measure of general massofta;t Secand pnncipal component accounted for> 13% of vanat1on in dependency structure, and provided a measure of general size of tail.
Genetic and phenotypic correlations between all studied traits were g1ven in Tables 23-28 Moderate posit1ve genetic correlation were obtained between principal component with all tail measurements, specially with thickness of tall. It IS proposed that a relationship exists between principal component with thickness of tall IIcould be concluded that thickness would g1ve an accurate indication of mass of tail, as well as being easily measured. So that we can use thickness of tail only to indicated to mass of tail.