scholarly journals A Replicated Test for Correlated Responses in Egg Weight and Early Growth Rate from Selection for Hatching Time in the Fowl

1981 ◽  
Vol 60 (1) ◽  
pp. 38-44 ◽  
Author(s):  
H. PALOMARES-HILTON ◽  
B.B. BOHREN
Keyword(s):  
Growth Rate ◽  
Early Growth ◽  
Correlated Responses ◽  
Egg Weight ◽  
Hatching Time ◽  
Selection For

Selection for lean growth rate and correlated responses in litter traits in a synthetic line of Yorkshire-Meishan pigs

2001 ◽  
Vol 81 (2) ◽  
pp. 205-214 ◽  
Author(s):  
P. Chen ◽  
T. J. Baas ◽  
J. C. M. Dekkers ◽  
L. L. Christian
Keyword(s):  
Growth Rate ◽  
Regression Coefficients ◽  
Correlated Response ◽  
Selection Line ◽  
Control Line ◽  
Correlated Responses ◽  
Lean Growth ◽  
Litter Traits ◽  
Selection For ◽  
Synthetic Line

Selection for lean growth rate (LGR) was conducted for four generations in a synthetic line of Yorkshire-Meishan pigs to study the effectiveness of selection for LGR and correlated responses in litter traits. Lean growth rate was estimated from ultrasound measurements of 10th-rib backfat thickness and longissimus muscle area. In the selection line, 7 boars and 20 gilts with the highest LGR were selected to produce the next generation. The generation interval was 13 mo and the average selection differential per generation was 1.1 phenotypic standard deviation units. A contemporaneous control line was maintained by randomly selecting 5 boars and 15 gilts. Data from a total of 1057 pigs sired by 58 boars and out of 133 sows were available from the two lines. Selection responses were estimated from deviations of the selection line from the control line using least squares (LS) and by multiple trait derivative-free restricted maximum likelihood analysis using an animal model (AM). The estimate of response to selection per generation using LS was 9.4 ± 0.95 g d–1 for LGR. The corresponding estimate from the AM was 9.8 ± 0.51 g d–1. Correlated responses in litter traits were regressed on generation. For the LS method, regression coefficients were negative but not significant (P > 0.05) for total number born, number born alive, and number at 21 d and at 42 d. Significant, positive correlated responses occurred in 42-d litter weight and 21-d piglet weight (P < 0.05). For the AM method, the regression coefficients were also negative, but were not significant (P > 0.05) for numberalive at birth, at 21 d, and at 42 d. A significant positive correlated response occurred only for 42-d litter weight (P < 0.05). Although results are based on a population of limited size, it can be concluded that selection for LGR in a synthetic line is effective and should have little effect on litter traits. Key words: Pigs, selection, lean growth rate, correlated response

CORRELATED RESPONSES IN EGG QUALITY TRAITS TO SELECTION FOR EARLY BODY WEIGHT IN MEAT-TYPE CHICKENS

1972 ◽  
Vol 14 (3) ◽  
pp. 477-482 ◽  
Author(s):  
V. Buvanendran ◽  
E. S. Merritt
Keyword(s):  
Body Weight ◽  
Egg Quality ◽  
Correlated Response ◽  
Quality Traits ◽  
Correlated Responses ◽  
Egg Weight ◽  
Shell Color ◽  
Blood Spots ◽  
Selection For ◽  
Meat Type

The correlated responses in egg quality traits to selection for high early body weight were studied in seven meat-type populations comprising five selected and two control lines. Traits studied were specific gravity, egg weight, albumen height, Haugh units, shell color, egg shape, shell roughness, wrinkling and asymmetry, and incidence of blood spots, meat spots and double yolks. Significant (P < 0.05 or < 0.01) correlated changes, as determined by the regression of correlated response (egg quality traits) on primary response (body weight), were obtained for egg weight, albumen height, Haugh units, asymmetry of shell and blood spots. All but blood spots increased with selection for high body weight. Shell color showed a consistent trend towards a darker color with increasing body weight. Scores for roughness of shell and, with one minor exception, the incidence of double yolks, also showed consistent trends (positive) with increasing body weight. Estimates of genetic correlations, derived directly from intra-line genetic analyses of the six pedigreed populations in the experiment, were in most cases in reasonable agreement with realized estimates.

scholarly journals Correlated responses to selection on body size in Drosophila melanogaster

1999 ◽  
Vol 74 (1) ◽  
pp. 43-54 ◽  
Author(s):  
LINDA PARTRIDGE ◽  
ROSALIE LANGELAN ◽  
KEVIN FOWLER ◽  
BAS ZWAAN ◽  
VERNON FRENCH
Keyword(s):  
Growth Rate ◽  
Drosophila Melanogaster ◽  
Body Size ◽  
Larval Development ◽  
Growth Period ◽  
Cell Number ◽  
Correlated Responses ◽  
Larval Weight ◽  
Thorax Length ◽  
Selection For

Correlated responses to artificial selection on body size in Drosophila melanogaster were investigated, to determine how the changes in size were produced during development. Selection for increased thorax length was associated with an increase in larval development time, an extended growth period, no change in growth rate, and an increased critical larval weight for pupariation. Selection for reduced thorax length was associated with reduced growth rate, no change in duration of larval development and a reduced critical larval weight for pupariation. In both lines selected for thorax length and lines selected for wing area, total body size changed in the same direction as the artificially selected trait. In large selection lines of both types, the increase in size was achieved almost entirely by an increase in cell number, while in the small lines the decrease in size was achieved predominantly by reduced cell size, and also by a reduction in cell number. The implications of the results for evolutionary-genetic change in body size in nature are discussed.

Carcass composition in pigs selected for components of efficient lean growth

1994 ◽  
Vol 1994 ◽  
pp. 15-15
Author(s):  
E.A. Bruce ◽  
N. D. Cameron ◽  
M.K. Curran
Keyword(s):  
Growth Rate ◽  
Divergent Selection ◽  
Carcass Composition ◽  
Correlated Responses ◽  
Large White ◽  
Lean Growth ◽  
Selection For

This study determined the correlated responses in carcass composition after four generations of divergent selection for components of efficient lean growth rate in Large White (LW) and Landrace (LR) pigs.

Selection for components of efficient lean growth rate in pigs 1. Selection pressure applied and direct responses in a Large White herd

1994 ◽  
Vol 59 (2) ◽  
pp. 251-262 ◽  
Author(s):  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Divergent Selection ◽  
Correlated Response ◽  
Food Conversion ◽  
Correlated Responses ◽  
Direct Response ◽  
Large White ◽  
Selection For ◽  
The Difference ◽  
And Control

AbstractResponses to four generations of divergent selection for lean groivth rate with ad-libitum feeding (LGA), for lean food conversion (LFC) and for daily food intake (DFI) in Large White pigs were studied. The LGA (LFC) selection criterion was designed to obtain equal correlated responses in growth rate (food conversion ratio) and carcass lean content, measured in phenotypic s.d. The selection criteria had phenotypic s.d. of 27, 29 and 253 units, respectively, and results are presented in s.d. units. There was a total of 3537 pigs, with an average of 40 boars and 40 gilts performance tested in each of the high, low and control lines per generation and the lines consisted of 10 sires and 20 dams. The generation interval was equal to 13·5 months. Animals were performance tested in individual pens with mean starting and finishing weights of 30 kg and 85 kg respectively.Cumulative selection differentials in the three selection groups were 5·8, 3·6 and 3·3 phenotypic s.d. for LGA, LFC and DFI respectively. Direct responses to divergent selection were 1·7, 1·3 and 1·2 (s.e. 0·17) for LGA, LFC and DFI. The correlated response in LFC (1·6 (s.e. 0·18)) with selection on LGA was greater than the direct response in LFC. Conversely, the direct response in LGA was greater than the correlated response (1·1 (s.e. 0·18)) with selection on LFC. The response in LFC (–1·1 (s.e. 0·17)) with selection on DFI was similar in size but opposite in sign to the direct response in LFC. Responses were asymmetric about the control, as the high LGA and LFC responses were proportionately smaller (0·74 and 0·58) than low line responses. In contrast, the difference between the high DFI and control was four times greater than the difference between low line and control.Heritabilities of LGA, LFC and DFI were 0·38, 0·35 and 0·29 (s.e. 0·03), when estimated by residual maximum likelihood, with common environmental effects of 0·09 (s.e. 0·02). Genetic correlations for LGA with LFC and DFI were positive, 0·76 (s.e. 0·03) and 0·23 (s.e. 0·07), but the genetic correlation between DFI and LFC was negative, –0·45 (s.e. 0·06). The experiment demonstrated that substantial responses to selection can be achieved in LGA, LFC and DFI. Selection on LGA resulted in larger direct and correlated responses than selection on LFC.

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