Phenotypic and genetic parameters of fleece traits and live weight in South Australian Angora goats

Gifford, D. R.; Ponzoni, R. W.; Lampe, RJ; Burr, John

doi:10.1016/0921-4488(91)90153-h

Cited by 31 publications

(13 citation statements)

References 8 publications

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“…All the available estimates are for body weight at 8 months and older, and most of these are based on sire model analyses (Yal in, 1982;Nicoll, 1985;Nicoll et al, 1989;Gifford et al, 1991;. The heritabilities estimated in this study with animal models fall within the range (0.10 to 0.47) reported in the literature (above) for body weight in Angora goats.…”

Section: Resultssupporting

confidence: 54%

Genetic analysis of body weight in South African Angora kids and young goats

Snyman¹

2012

SA J. An. Sci.

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The data used for this study consisted of 27 485 kid records, the progeny of 599 sires and 10 077 dams, and were collected on the 2000-to 2009-born kids of 11 Angora goat studs. Variance and covariance components and ratios pertaining to direct additive genetic variation, maternal additive genetic variation, maternal permanent environmental variation, and the relationship between direct and maternal effects for birth weight (BW; kg), weaning weight (WW; kg) and body weight at 8, 12 and 16 months (W8, W12 and W16; kg) were estimated with the ASReml program. Direct additive heritability estimates of 0.22, 0.20, 0.12, 0.34 and 0.58 were obtained for BW, WW, W8, W12 and W16, respectively. Maternal heritabilities were 0.10, 0.09, 0.03 and 0.06 for BW, WW, W8 and W12, respectively, while maternal environmental effects of 0.13, 0.11, 0.06 and 0.04 were estimated for the latter traits, respectively. An unfavourable correlation of -0.38 was obtained between direct and maternal genetic effects for BW. Low to medium positive direct genetic correlations were estimated between birth weight and body weights recorded at a later stage in life. High positive direct genetic correlations were estimated among WW, W8, W12 and W16. The maternal genetic correlations obtained between birth weight and the other body weights were medium to high. Phenotypic correlations among the traits ranged from low to high. Genetic trends of body weight at different ages indicate that although not many breeders use objective measurement as a selection tool, body weight increased slightly in the 11 studs over the 10-year study period. Since reproduction and body weight should be included in a selection programme for Angora goats, the relationship between the direct and maternal additive effects should be clarified. The importance of a sufficiently structured and related pedigree, especially on the part of the dams and maternal grand dams, has been highlighted in this study. As this is one of the constraints of this data set, data collection in the Angora goat industry should continue until a suitably structured data set has been built up that could be used to estimate multi-trait breeding values for the industry.___________________________________________________________________________________

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Section: Resultssupporting

confidence: 54%

Genetic analysis of body weight in South African Angora kids and young goats

Snyman¹

2012

SA J. An. Sci.

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“…This suggests that the genetic effects on CFWt are mostly intermediated via differences in liveweight as has been suggested for Merino sheep (Thompson and Barlow 1986). A positive phenotypic relationship between liveweight and mohair CFWt has been reported in previous studies of Angora goats from South Africa, Texas, Turkey, Australia and New Zealand (Shelton and Bassett 1970;Yalçin et al 1979;Nicoll et al 1989;Gifford et al 1991;Snyman and Olivier 1996). Wool CFWt is also phenotypically positively related to liveweight of Merino sheep (Huisman and Brown 2008).…”

Section: Influence Of Other Factorssupporting

confidence: 60%

The allometric relationship between clean mohair growth and the fleece-free liveweight of Angora goats is affected by liveweight change

McGregor

Butler²,

Ferguson³

2013

Anim. Prod. Sci.

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Clean fleece weight (CFWt) is affected by liveweight and change in liveweight in Merino sheep, Angora and cashmere goats. However, how these relationships progress as animals age has not been elucidated. Measurements were made over 12 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins including South African, Texan and interbred admixtures of these and Australian sources. Records of breed, sire, dam, date of birth, dam age, birthweight, birth parity, weaning weight, liveweight, fleece growth and fleece quality were taken for does and castrated males (wethers) (n = 267 animals). Fleece-free liveweights (FFLwt) were determined for each goat at shearing time by subtracting the greasy fleece weight from the liveweight recorded immediately before shearing. The average of the FFLwt at the start of the period and the FFLWt at the end of the period was calculated (AvFFLwt). Liveweight change (LwtCh) was the change in FFLwt over the period between shearings. A restricted maximum likelihood model was developed for CFWt, after log10 transformation, which allowed the observations of the same animal at different ages to be correlated in an unstructured manner. A simple way of describing the results is: CFWt = κ (AvFFLwt)β, where κ is a parameter that can vary in a systematic way with shearing age, shearing treatment and LwtCh; and β is an allometric coefficient that only varies with LwtCh. CFWt was proportional to FFLwt0.67 but only when liveweight was lost at the rate of 5–10 kg during a shearing interval of 6 months. The allometric coefficient declined to 0.3 as LwtCh increased from 10 kg loss to 20 kg gain during a shearing interval. A consequence is that, within an age group of Angora goats, the largest animals will be the least efficient in converting improved nutrition to mohair.

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“…It is generally accepted that the lower limit of body weight at which young Angora ewes can be expected to conceive successfully, is 25 kg (Van der Westhuizen et al, 2004). The relatively poor growth rate of Angora kids (Yalcin, 1982;Nicoll, 1985;Nicoll et al, 1989;Gifford et al, 1991) compared to other small-stock breeds is well known. Many young ewes do not reach the target weight at 18 months of age when they are mated for the first time.…”

Section: Introductionmentioning

confidence: 99%

Body weight and growth rate of South African Angora goat kids under different pre- and post-weaning management systems

Snyman¹

2007

SA J. An. Sci.

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The data used for this study were collected on 16 644 kids born between 2000 and 2004 in 12 different Angora goat studs representing different management systems. Body weight and growth rate of kids from birth to 16 months of age, as well the 18-and 21-month body weights and first kidding performance of ewe kids were evaluated. Variable growth rates were recorded among kids in the different studs, which can be ascribed largely to different environments and supplementary feeding practices. The pre-weaning growth performance of both ram and ewe kids was satisfactory. However, the same did not apply for post-weaning growth rates. In those flocks where kids did not receive any supplementary feeding after weaning, their body weights remained virtually constant from weaning up to eight months of age. This phenomenon where especially ewe kids did not grow well after weaning, needs to be investigated further, since it influences the reproductive ability of young ewes directly. This was evident from the poor reproductive performance of young ewes in some of the studs. On the other hand, the effect of different pre-weaning treatments did not seem to be carried over to body weight and reproductive performance at first kidding age.

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Phenotypic and genetic parameters of fleece traits and live weight in South Australian Angora goats

Cited by 31 publications

References 8 publications

Genetic analysis of body weight in South African Angora kids and young goats

Genetic analysis of body weight in South African Angora kids and young goats

The allometric relationship between clean mohair growth and the fleece-free liveweight of Angora goats is affected by liveweight change

Body weight and growth rate of South African Angora goat kids under different pre- and post-weaning management systems

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