scholarly journals Variation of mohair staple length across Angora goat fleeces: implications for animal selection and fleece evaluation

2009 ◽  
Vol 147 (4) ◽  
pp. 493-501 ◽  
Author(s):  
B. A. McGREGOR ◽  
K. L. BUTLER
Keyword(s):  
Maximum Likelihood ◽  
Genetic Selection ◽  
Restricted Maximum Likelihood ◽  
Individual Animal ◽  
Actual Range ◽  
Selection For ◽  
Animal Effects ◽  
Angora Goat ◽  
Anterior Posterior ◽  
Staple Length

SUMMARYThe present study aimed to determine how the average mohair staple length (SL) differences between nine sampling sites vary between sex and flock, to identify differences in SL variability between sampling sites as a result of between-animal and between-sire variability and to determine SL correlations between sampling sites in between-animal and between-sire variability. Australian Angora goats (n=301) from two farms in southern Australia were sampled at 12 and 18 months of age at nine sites (mid side, belly, brisket, hind flank, hip, hock, mid back, neck and shoulder). Staples were taken prior to shearing at skin level and stretched SL determined. For each shearing, differences in SL between sampling sites, how these differences were affected by farm, sex and sire, and the covariance between sites for sire and individual animal effects were investigated by restricted maximum likelihood (REML) analyses. The median mid-side SL at 12 and 18 months of age was 110 and 130 mm, respectively, but the actual range in mid-side SL was 65–165 mm. There was an anterior–posterior decline in SL with the hock being particularly short. There was no evidence that the between-site correlation of the sire effects differed from 1, indicating that genetic selection for SL at one site will be reflected in SL over the whole fleece. However, low heritabilities of SL at the hock, belly and brisket or at any site at 12 months of age were obtained. There was more variability between sites than between sires, but the between-animal variation was greater. The hip and mid-back sites can be recommended for within-flock (culling) and genetic selection for SL due to their low sampling variability, moderate heritability and ease of location.

scholarly journals GENETIC PARAMETERS OF GIROLANDO CROSSBRED COWS IN DAIRY HERDS IN THE STATE OF ACRE, BRAZIL

2020 ◽  
Vol 23 (1cont) ◽  
Author(s):  
Andressa Pereira Braga ◽  
José Marques Carneiro Júnior ◽  
Antônia Kaylyanne Pinheiro ◽  
Maurício Santos Silva
Keyword(s):  
Maximum Likelihood ◽  
Milk Production ◽  
Genetic Parameters ◽  
Heritability Estimate ◽  
Restricted Maximum Likelihood ◽  
Dairy Herds ◽  
Genetic Progress ◽  
Linear Unbiased Prediction ◽  
Best Linear Unbiased ◽  
Selection For

This study aimed at estimating genetic parameters for milk production and conformation characteristics in Girolando crossbred dairy cows reared in the High and Low Acre region using the restricted maximum likelihood methodology, under an animal model. We estimated the variance components and genetic parameters using the REML/BLUP procedure (Restricted Maximum Likelihood Methodology/Best Linear Unbiased Prediction). The estimated average for milk production for 305 days of lactation (P305) was of 1523.25 ± 481.11 kg, with a heritability of 0.38 for this characteristic. The conformation characteristics showed no significant correlation with milk production. The phenotypical correlations between the linear characteristics of type were, in general, positive and moderate. The P305 obtained in this study can be considered low and indicates that there is a possibility of increasing milk production through selection in herds along with the use of tested and proven bulls. The heritability estimate found (0.38) indicates that there is genetic variability for milk production, demonstrating that selection for this characteristic would result in genetic progress.

Changes in skin and fleece characteristics of Scottish cashmere goats following selection for increased annual production and decreased fibre diameter

2003 ◽  
Vol 76 (3) ◽  
pp. 517-522 ◽  
Author(s):  
M. Merchantt ◽  
D. J. Riach
Keyword(s):  
Genetic Selection ◽  
Fibre Diameter ◽  
Control Line ◽  
Selected Lines ◽  
Financial Return ◽  
Fine Line ◽  
Growing Period ◽  
Cashmere Goats ◽  
Selection For ◽  
Staple Length

AbstractThe aim of this experiment was to determine the mechanisms involved in changes in the production of cashmere as a consequence of genetic selection. Skin follicle parameters and pattern of cashmere growth were compared in two selected lines of Scottish cashmere goats and a randomly bred control line. One line, the fine line, had been selected for low fibre diameter, and this had resulted in lower fibre diameter, but the weight of cashmere produced had also been reduced. Selection for fibre quantity and quality to give maximum financial return (the value line) had increased cashmere weight without a significant increase in cashmere diameter.Skin follicle density and the ratio of secondary to primary follicles (S/P ratio) were measured at 5 months of age in 25 female kids from each line. The density of follicles in the value line was greater (P · 0.05) than that in the fine or control lines (means were 21·8, 19·8 and 20·1 follicles per mm2 respectively, s.e.d. 0.73). S/P ratio increased (P · 0.001) from control to fine to value lines (means were 6.5, 7.7 and 8.4 respectively, s.e.d. = 0.30).The rate of cashmere growth (length), peak cashmere length, the duration of the cashmere growing period and dates of initiation and cessation of growth were measured in the same 25 goats from each line between 2 and 3 years of age. These traits were estimated from the regression of measurements of staple length taken at approximately 6-weekly intervals from the start of the growing period until peak staple length was reached. Measurements were made on the shoulder, mid side and hip. There was no difference in cashmere growth rate between the selection lines (average 0·29 (s.e. 0.006) mm/day). Cashmere growth started earliest in the value line and latest in the fine line but the date of cessation of growth was not different. This affected the duration of the growing period which was 183, 163 and 214 days (s.e.d. 9.6, P · 0.001) for the control, fine and value lines respectively. Peak staple length of cashmere was longest in the value line.Increased weight of cashmere in the value line was brought about through an increase in the number of secondary follicles and by an increase in the length of cashmere due to an increase in the duration of the growing period.

Selection for predicted carcass lean content in Scottish Blackface sheep

1993 ◽  
Vol 56 (3) ◽  
pp. 379-386 ◽  
Author(s):  
S. C. Bishop
Keyword(s):  
Body Weight ◽  
Maximum Likelihood ◽  
Environmental Conditions ◽  
Restricted Maximum Likelihood ◽  
Realized Heritability ◽  
Selected Lines ◽  
Maternal Performance ◽  
Selection For

AbstractScottish Blackface sheep have been selected for either increased or decreased predicted carcass lean content at 20 weeks of age, using an index combining ultrasonic backfat depth and body weight. The index was designed to alter carcass lean content without changing body weight. After 4 years there have been large responses in the index and fat depth, the proportional difference between the divergent lines in fat depth is 0·28, but body weight and ultrasonic muscle depth have not changed between the lines. The realized heritability for the index is 0·45. Heritabilities for the index, ultrasonic fat depth, body weight and ultrasonic muscle depth, calculated using multivariate restricted maximum likelihood, are 0·47 (s.e. = 0·14), 0·39 (s.e. 0·13), 0·23 (s.e. 0·12) and 0·36 (s.e. 0·14), respectively. The selected lines will be used to investigate relationships between carcass lean content, viability and maternal performance under the harsh environmental conditions encountered in the Scottish hill environment.

Individual animal model estimates of genetic parameters for reproduction traits of landrace pigs performance tested in a commercial nucleus herd

1997 ◽  
Vol 65 (2) ◽  
pp. 285-290 ◽  
Author(s):  
R. E. Crump ◽  
C. S. Haley ◽  
R. Thompson ◽  
J. Mercer
Keyword(s):  
Animal Model ◽  
Maximum Likelihood ◽  
Genetic Parameters ◽  
Performance Test ◽  
Gestation Length ◽  
Individual Animal ◽  
Litter Weight ◽  
Reproduction Traits ◽  
Selection For ◽  
Landrace Population

AbstractIndividual animal model restricted maximum likelihood was used to estimate genetic parameters for number of piglets born, number born alive, total litter weight, average piglet weight and gestation length for a commercial Landrace population undergoing selection for performance test traits. Estimates of heritabilities and repeatabilities (around 0·1 and 0·2, respectively) for number born and number born alive are in line with other published results. Heritabilities around 0·2 and repeatabilities around 0·3 were observed for average piglet weight and gestation length, while for litter weight these values were between 0·11 and 0·15 for heritabilities and around 0·2 for repeatabilities. Estimates of common litter of birth effects and maternal genetic effects were very low across all traits analysed.

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