Predicted and realized responses to selection for an index of bone length and body weight in Scottish Blackface sheep 2. Correlated responses in lifetime productivity

1986 ◽  
Vol 43 (3) ◽  
pp. 437-445 ◽  
Author(s):  
K. D. Atkins ◽  
R. Thompson
Keyword(s):  
Body Weight ◽  
Population Genetic ◽  
Genetic Correlations ◽  
Reproduction Rate ◽  
Base Population ◽  
Correlated Responses ◽  
Genetic Response ◽  
Bone Length ◽  
Body Weights ◽  
Selection For

ABSTRACTA selection experiment with Scottish Blackface sheep was used to compare predicted and realized correlated responses to selection. Three lines were maintained between 1956 and 1974 in which selection was either at random or for high and low values of an index of cannon-bone length at 8 weeks of age adjusted for body weight at the same age.There was no evidence of asymmetrical responses in any trait. Selection for increased cannon-bone length, adjusted for body weight, resulted in (i) increased body weights at all ages between birth and maturity, (ii) increased reproduction rate, principally from increased litter size but also from small responses in ewe fertility and lamb survival and (iii) decreased survival of adult ewes. The realized genetic correlations were relatively small (up to 0·3) but mostly significantly different from zero, whereas base population genetic correlation estimates were very imprecise. The realized responses in reproduction rate were probably a consequence of the genetic response in body weight.

Genetic Parameters of Body Weights in Hill Sheep

1984 ◽  
Vol 1984 ◽  
pp. 45-45 ◽  
Author(s):  
K.D. Atkins
Keyword(s):  
Body Weight ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Body Growth ◽  
Optimal Time ◽  
Correlated Responses ◽  
Body Weights ◽  
Selection For

There are few published studies on the genetics of body growth to maturity in sheep. Such information is required for choosing an optimal time of selection for body weight and to predict correlated responses to selection at all stages of an animal's lifetime. The data were derived from a randomly selected control flock of Scottish Blackface sheep on a hard heather hill research farm in Peeblesshire, Scotland. The objectives of the analysis were to estimate the heritability of body weight at various ages between birth and maturity, and the genetic correlations between these weights.

Response to selection in Australian Merino sheep. III. Single character selection for high and low values of wool weight and its components

1970 ◽  
Vol 21 (6) ◽  
pp. 955 ◽  
Author(s):  
HN Turner ◽  
MG Brooker ◽  
CHS Dolling
Keyword(s):  
Body Weight ◽  
Unit Area ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Initial Response ◽  
Skin Area ◽  
Correlated Responses ◽  
Fibre Number ◽  
Selection For ◽  
Staple Length

Direct and correlated responses are reported for 10 traits in eight pairs of lines under selection for high and low values of single characteristics : clean wool weight per head, clean wool weight per unit skin area (measured only in the groups under selection for it), body weight, wrinkle score, fibre number per unit skin area (adjusted for body weight), fibre diameter, staple length, and percentage clean yield. All groups showed overall divergence in the character under selection, though response was not always symmetrical, and in two cases (long staple and low fibre number) there was no continuing response after the initial response to extreme selection of the base parents. In all except one case, whenever previous estimates of genetic correlation were at the level of 0.2 or higher, correlated responses were in the predicted direction, though not always symmetrical in magnitude. The exception was a previously reported negative correlation between fibre number and staple length, which was not exhibited under selection for either character. Where two characters of a pair were under selection, reciprocal responses agreed in sign; magnitude will be examined in a later paper. Wool per unit area was shown to have a greater influence on clean wool weight than that of surface area, with staple length on this occasion being the most important component of wool per unit area. Reasons for an apparent decrease in the relative importance of fibre number are discussed. Three other points of importance in sheep breeding are again emphasized by these results : 1. Crimp in several pairs of groups was a poor indicator of fibre diameter. 2. Increases in clean wool weight were associated with falls in crimp number, even though fibre diameter actually became finer; diameter, not crimp, should therefore be used as a guide to wool quality. 3. The absence of genetic correlations DL and NL indicates that selection can be for high N (fibre number) with high L (staple length) and low D (fibre diameter) -in other words, a desirable fleece -with no impeding genetic correlations.

Predicted and realized responses to selection for an index of bone length and body weight in Scottish Blackface sheep 1. Responses in the index and component traits

1986 ◽  
Vol 43 (3) ◽  
pp. 421-435 ◽  
Author(s):  
K. D. Atkins ◽  
R. Thompson
Keyword(s):  
Body Weight ◽  
Genetic Correlations ◽  
Generalized Least Squares ◽  
Phenotypic Variance ◽  
Base Population ◽  
Population Parameters ◽  
Selected Lines ◽  
Bone Length ◽  
Component Traits ◽  
Least Squares Estimates

ABSTRACTA selection experiment with Scottish Blackface sheep was used to compare predicted and realized responses to selection. Three closed lines, of approximate annual size of 270 ewes and 10 rams, were maintained between 1956 and 1974, in which selection was at random, or for high and low values of an index of cannon-bone length at 8 weeks of age adjusted for body weight at the same age. An unselected base flock (1954-55) and the randomly selected line were used to estimate base population parameters, while the selected lines were used to estimate realized responses to selection.Heritabilities and genetic correlations were obtained in the unselected lines from a variety of collateral and ancestral relationships. The important components of phenotypic variance were estimated and likely responses to selection predicted for the index and its two component traits. Realized responses to selection were estimated from the regression of response on selection differential. The expected variance-covariance matrix of observed responses was included in generalized least-squares estimates of these regressions.The realized heritability of the index under selection, estimated from the divergence of selected lines, was 0·52 (s.e. 0·02). After allowing for the expected reduction in heritability arising from linkage disequilibrium, this was very similar to the base population estimate of 0·56 (s.e. 0·04). The responses in the component traits of the index were also very close to those expected from base population parameters

Studies on Growth Performance and Genetic Parameters of Three Varieties of Domesticated Japanese Quail

2020 ◽  
Author(s):  
M Monika ◽  
J J Rokade ◽  
R Narayan ◽  
V K Saxena ◽  
Snehasmita Panda ◽  
...  
Keyword(s):  
Body Weight ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Field Testing ◽  
Pure Line ◽  
Japanese Quails ◽  
Quantitative Genetic ◽  
Body Weights ◽  
Selection For ◽  
Mortality Percentage

The quantitative genetic study involving a pure line mating of 160 pairs of three varieties of domesticated Japanese quails (CARI-Ujjawal; CARI-Suneheri and CARI-Brown) were maintained under individual pedigree cages for breeding. A total of 6221 quail chicks from three hatches comprising three varieties were used for this study. Among them, CARI-Ujjawal has higher hatchability with less rearing mortality percentage. CARI-Ujjawal had highest (plessthan0.01) body weight at all ages when compared to the other two varieties. The heritability estimates on body weight (0-5 weeks) among the varieties range from low to moderate in all the three varieties. The positive correlation was observed among all the varieties at different ages. High genetic correlations between body weights at early as well as later ages confirms that selection for body weight at early ages would improve body weight at later (maturity) ages. Amongst all, CARI-Suneheri was having better heritability values and during further generations of selections it performed also well to improve because of its better heritability. Also from above results this variety could be recommended for broiler quail breeding after field testing.

scholarly journals Effects of selection for independent changes in two highly correlated body weight traits of mice

1977 ◽  
Vol 29 (2) ◽  
pp. 133-145 ◽  
Author(s):  
J. C. McCarthy ◽  
D. P. Doolittle
Keyword(s):  
Body Weight ◽  
Response Selection ◽  
The Other ◽  
Index Selection ◽  
Correlated Responses ◽  
Body Weights ◽  
Independent Culling ◽  
Selection For ◽  
Highly Correlated

SUMMARYMice were selected for high and low body weight at 5 and at 10 weeks of age. Selection was performed (1) separately for each trait, and (2) for various combinations of the two traits, using (a) independent culling levels and (b) restricted indices. Two-way selection for each trait separately gave large responses and correlated responses. Selection by independent culling levels intended to increase 5-week weight while restricting change in 10-week weight gave no demonstrable response; selection by culling levels intended to decrease 5-week weight while restricting change in 10-week weight resulted in decreases in body weights at both ages. Index selection, intended to change weight at one age while holding that at the other age constant, was generally successful. Observed responses did not conform very well with predicted responses for either index or culling levels selection. The significance of these observations in regard to the problem of selection involving restriction of traits is discussed.

Genetic and phenotypic relationships between fertility and wool production in 2-year-old Merino sheep

1967 ◽  
Vol 18 (3) ◽  
pp. 515 ◽  
Author(s):  
JP Kennedy
Keyword(s):  
Body Weight ◽  
Genetic Correlations ◽  
Standard Errors ◽  
Phenotypic Correlation ◽  
Correlated Responses ◽  
Merino Sheep ◽  
Wool Production ◽  
Phenotypic Correlations ◽  
Selection For ◽  
Fertility Traits

Records of the lambing and weaning performance (fertility) of 2-year-old Peppin Merino ewes were analysed. Repeatability and heritability of number of lambs born and weaned were low. Heritability of number of lambs born was significantly different from zero (0.20 ± 0.10). Phenotypic and genetic correlations between the fertility traits and greasy wool weight, all measured at approximately 15 months of age, were calculated. Phenotypic correlations between number of lambs born or weaned and greasy wool weight were negative and significant. The phenotypic correlation between number of lambs weaned and clean wool weight was negative and significant. Significant negative genetic correlations were found between number of lambs born and both greasy wool weight and clean wool weight. Genetic correlations between number of lambs weaned and the fleece and body traits had very large standard errors. The results were used to estimate correlated responses in fertility resulting from selection for greasy wool weight, clean wool weight, and body weight of –0.08i, –0.13i, and 0.03i respectively.

Effects of divergent selection for body weight on bone length and diameter in mice

1977 ◽  
Vol 24 (1) ◽  
pp. 77-82 ◽  
Author(s):  
A. C. B. Hooper
Keyword(s):  
Body Weight ◽  
Genetic Control ◽  
Maternal Effects ◽  
General Pattern ◽  
Intramembranous Ossification ◽  
Correlated Responses ◽  
Bone Length ◽  
Quantitative Genetic ◽  
Selection For ◽  
Genetically Determined

SUMMARYThe length and diameter of the humerus, ulna, femur and tibia were studied at generations 10 and 14 in lines of mice selected for high and low body weight at 10 weeks of age.Although some deviations from control were not significant, a general pattern of correlated responses was evident. The divergences of high and low line means for bone length and diameter were significant in the four bones, confirming the contribution of these parameters to genetically determined alterations in body weight. Maternal effects did not affect bone length and diameter and heterosis was not important in the genetic control of these parameters. Unlike bone length, bone diameter continued to diverge in response to the additional four generations of selection. There may therefore be differences in the quantitative genetic control of bone length and diameter and consequently in the control of endochondral and intramembranous ossification.

scholarly journals ESTIMATES OF PHENOTYPIC AND GENETIC CORRELATIONS IN WEST AFRICAN DWARF GOATS

2021 ◽  
Vol 21 ◽  
pp. 47-50
Author(s):  
I. K. Odubute ◽  
J. O. Akinokun
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Genetic Correlations ◽  
Correlation Coefficients ◽  
West African ◽  
West African Dwarf ◽  
West African Dwarf Goat ◽  
Body Weights ◽  
Selection For ◽  
Size At Birth

Records on 848 West African dwarf goat kids and 220 kiddings over a period of eight year's (1982-1989) were analyzed. The records were used to provide estimates of phenotypic and venetic correlations among parity, kidding interval, litter size at birth and body weight at various ages. Plenotypic correlation coefficients of +0.33 (P<0.01) and -0,17 (P<0.01) were obtained when parity was correlated with litter size at birth and kidding interval respectively. Phenotypic correlations among body weights were generally positive and significant (P<0.01). Parity was positively correlated (P<0.01) with body weight at the various ages except at 1 year (P>0.05). Litter size was, however, negatively correlated (P<0.01) with body weight at the various ages except at 1 year (P<0.05). The genetic correlations among body weights at variuus ages were positive and significant (P<0.01). Selection for body weight at in earlier age especially at 3 months is likely to result in improvement of yearling body weight.

scholarly journals Correlated responses to selection for large body size in oMt1a-oGH transgenic mice: organ traits

2000 ◽  
Vol 23 (4) ◽  
pp. 771-780 ◽  
Author(s):  
K.R. Parks ◽  
E.J. Eisen ◽  
J.D. Murray
Keyword(s):  
Drinking Water ◽  
Body Weight ◽  
Genetic Correlations ◽  
Large Body ◽  
High Growth ◽  
Correlated Responses ◽  
Large Body Size ◽  
Organ Weights ◽  
Growth Increase ◽  
Selection For

The objective of the present study was to compare correlated responses in liver, spleen, kidney, heart and testis absolute weights and as a percentage of 8-week body weight following selection for large 8-week body weight in twice-replicated nontransgenic and transgene-carrier lines of mice from two genetic backgrounds. The transgene was an ovine metallothionein 1a-ovine growth hormone (oMt1a-oGH) construct, which was activated by adding 25 mM ZnSO4 to the drinking water. Lines NM and NC were nontransgenic lines derived from a high-growth and randomly selected background, respectively. Lines TM and TC were transgene-carrier lines formed from the respective genetic backgrounds. Line CC was a nontransgenic control from the randomly selected background. At weaning, male mice from each line were assigned to either zinc supplemented or control drinking water. Toe-clips were assayed by PCR for the presence or absence of the transgene. Correlated responses of absolute weights of all organs in nontransgenic lines indicated moderately high genetic correlations of organ weights with body weight, but on a percentage of body weight basis, the correlated responses were much lower. The correlated responses in visceral organ weights were lower in the presence of the inactivated oMt1a-oGH transgene than in its absence. The presence of the activated oMt1a-oGH combined with the effects of selection for growth increase had a greater impact on increasing the size of the splanchnic organs than did selection for large body weight in the absence of the transgene.

GENETIC AND PHENOTYPIC PARAMETERS FOR DAILY GAIN AND BODY WEIGHTS IN SUFFOLK LAMBS

1985 ◽  
Vol 65 (3) ◽  
pp. 575-582 ◽  
Author(s):  
J. N. B. SHRESTHA ◽  
J. A. VESELY ◽  
J. P. CHESNAIS
Keyword(s):  
Genetic Correlations ◽  
Performance Testing ◽  
Genetic Response ◽  
Testing Program ◽  
Body Weights ◽  
Genetic And Phenotypic Correlations ◽  
Selection Indexes ◽  
Selection For ◽  
The Stability ◽  
Daily Gain

Body weights of 19 400 Suffolk lambs from the Federal-Provincial Canadian Record of Performance program were studied. The paternal half-sib estimate of heritability for daily gain from 50 to 100 days of age was 0.47 ± 0.04. The corresponding estimates for lamb weights at 50 and 100 days of age were 0.46 ± 0.04 and 0.43 ± 0.04, respectively. The moderate levels of heritability and the intermediate (16–25%) coefficient of variation in the Suffolk breed confirm that selection for daily gain and body weights would result in genetic response. Estimates of genetic and phenotypic correlations among daily gain from 50 to 100 days of age and 100-day lamb weight were 0.80 ± 0.02 and 0.73, respectively. Corresponding correlations among lamb weights at 50 and 100 days were 0.89 ± 0.02 and 0.76. Selection for daily gain from 50 to 100 days of age does not offer any advantage over selection based on lamb weight at 100 days when lamb weight at that age is the response criterion. Similarity in the estimates of genetic and phenotypic parameters from 1980 to 1983 indicates the stability of the estimates and their usefulness in selection indexes and predicting breeding values for sheep in the Canadian performance testing program. Key words: Suffolk, lamb weights, heritabilities, genetic correlations

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