Analysis of the existence of major genes affecting alpaca fiber traits1

Journal of Animal Science

Varona

Pun

et al. 2011

Self Cite

The alpaca is the most important fiber producer of the South American camelid species, and is an important source of income for the Andean communities. Nowadays, fiber diameter is considered the main selection objective in alpaca populations throughout the world. However, fiber diameter increases with the age of the animals, and it would be preferable to select those animals that maintain a thin fiber throughout their life span. The goal of this study was to describe the genetic relationship between fiber diameter at weaning age (6 mo) and the evolution of fiber diameter along the life span. The analysis of the evolution of fiber diameter was studied as a useful model for canalization and as a longitudinal trait by hierarchical Bayesian analysis. The results suggested that substantial genetic variation exists for fiber diameter and also for the variability and linear growth of the fiber diameter. Thus, a genetic selection program is plausible to modify the evolution of fiber diameter with time, together with a favorable correlated decrease in fiber diameter.

Section: Discussionsupporting

confidence: 52%

Section: Discussionmentioning

confidence: 94%

Genetic parameters for growth of fiber diameter in alpacas1

Journal of Animal Science

Varona

Pun

et al. 2011

Self Cite

“…The heritabilities found in this work showed that decreasing PM would be possible by artificial selection. These values were 0.225 and 0.237 for, respectively, PM and MFD for Huacaya genetic type, and 0.664 and 0.237 for Suri genetic type, suggesting the PM heritability in Suri genetic type the possible existence of a major gene segregating, maybe the same found for FD reported by Pérez-Cabal et al (2010). These values were similar than others estimated in other species, being 0.37 for PM in sheep (Sánchez et al, 2016), 0.23 in Angora goats (Allain and Roguet, 2006) and 0.29 in Argentinean lamas (Frank et al, 2011).…”

Section: Discussionmentioning

confidence: 51%

Genetic parameters for medullated fiber and its relationship with other productive traits in alpacas

Cruz¹,

Morante²,

et al. 2019

Animal

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The alpaca fiber diameter (FD) varies from 18 to 36 μm, being the finer fiber categories highly appreciated. However, the alpaca fiber presents some limitations in the textile industry due to the high incidence of fiber medullation and diameter variability, both reduces the comfort feeling of the garments. Decreasing or even removing medullation could be a possible selection objective in alpaca breeding programs for increasing economic value of the alpaca fiber. Therefore, the present work aimed to estimate genetic parameters regarding medullation traits, as well as the genetic correlations with other economical important traits, to be able to select the appropriate criteria to reduce or remove medullation on alpaca fiber and help to reduce the prickle factor in the garments. The data was collected from 2000 to 2017 and belonged to the Pacomarca experimental farm. There were 3698 medullation records corresponding to 1869 Huacaya and 414 Suri genetic types. The fiber samples were taken from the mid side, and were analyzed in an OFDA 100® device. The traits analyzed were percentage of medullation (PM), medullated fiber diameter (MFD), FD, standard deviation of FD, greasy fleece weight as fiber traits; density, crimp in Huacaya and lock structure in Suri, head conformation, leg coverage as morphological traits; weaning weight and age at first calving as secondary and functional traits. Genetic parameters were estimated via a multitrait restricted maximum likelihood. The heritabilities for PM and MFD were 0.225 and 0.237 in Huacaya genetic type and 0.664 and 0.237 in Suri genetic type, respectively; heritabilities for other traits were moderate for productive and morphological traits, and low to moderate for secondary and functional traits. The genetic correlations PM–FD and MFD–FD were high and favorable in both genetic types, between 0.531 and 0.975; the genetic correlation PM–MFD was 0.121 in Huacaya and 0.427 in Suri. The rest of genetic correlations with other traits were in general moderate and favorable. The repeatabilities were 0.556 and 0.668 for PM, and 0.322 and 0.293 for MFD in Huacaya and Suri genetic types, respectively. As a conclusion, PM was identified to be a good selection criterion, probably combined in an index with FD to reduce prickling factor.

“…their animals 2011;Morante et al, 2009;Cervantes et al, 2010;Pérez-Cabal et al, 2010;Paredes et al, 2013), and has implemented a strict genetic selection on their animals looking for a desired proportional improvement of some determined traits. As a consequence, success has been globally observed both in the performances and in the genetic trends, but this success has not been obtained in the expected proportionality.…”

Section: Proportional Expected Genetic Responsesmentioning

confidence: 99%

Weighting fibre and morphological traits in a genetic index for an alpaca breeding programme

Cervantes

Pérez-Cabal

et al. 2014

Animal

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Nowadays, the fibre diameter (FD) is considered the main selection objective in alpaca populations all over the world. International Committee for Animal Recording recommendations define the FD and its CV as the first two traits to be considered in breeding programmes for this specie. In addition to these main criteria, other selection criteria of economic value used are comfort factor (CF) or standard deviation (s.d.); also other less important traits being used as selection objectives are these morphological traits: density (DE), crimp (CR) or lock structure (LS) for, respectively, Huacaya (HU) and Suri (SU) ecotypes, head (HE), coverage (CO) and balance (BA). The goal of this study was to establish how to implement a combined selection index starting from genetic parameters and to study the expected correlation between genetic trends by considering different alternative procedures of weighting all the involved traits, and the consequences of a wrongly proceeding way. Heritabilities and genetic and phenotypic correlations were estimated from the data set belonging to the PACOMARCA experimental farm for SU and HU. Two approaches were used to check the consequences of a set of subjective weights essayed. The coefficients of selection indexes were obtained for two sets of reference weights. In addition, equivalent weights were drawn if applied those reference values as coefficients of hypothetical selection indexes directly on phenotypes; relative expected genetic responses were computed in different cases. Results showed that almost in all cases for both ecotypes, the weight applied to CF should be surprisingly negative. Concerning genetic responses, only CO was compromised in some cases for the HU ecotype. The essayed methodology allowed explaining the differences between ecotypes in the genetic trends. The proposed methodology was shown to be effective to study the relative importance of the traits granted by the manager of a breeding scheme.