Selection for Egg Mass in Different Social Environments 2. Estimation of Parameters in Selected Populations ,

An exponential curve, W = P-Qexp(- Rt), where W is egg weight at age t, was fitted to egg weights of individual pullets, and genetic parameters were estimated for P, Q and R, the residual standard deviation and other egg weight and egg production characters. The data consisted of records collected over six generations on more than 4000 pullets in two selection lines and a control line which originated from a synthetic gene pool of White Leghorn x Australorp crosses. The half-sib and offspring-on-parent regression estimates of heritability pooled over the lines were 0.23 and 0.33 for P, 0.14 and 0.20 for Q, and 0.14 and 0.25 for R. Genetic correlations were estimated to be -0.10 between P and Q, -0.46 between P and R, and 0.90 between Q and R. These estimates suggest that the egg weight v. age curve may be modified to increase the proportion of eggs in desirable weight grades and reduce the incidence of oversized eggs later in the production year. The genetic correlation between mean weight of first 10 eggs and egg weight at 62 weeks of age was estimated to be 0.68, further suggesting that early egg weight may be improved partly independently of late egg weight. The heritability estimates of egg mass output were not higher than those of egg number in spite of the highly heritable average egg weight being an important component of egg mass, probably because of the negative genetic correlation (r = -0.49) between egg number and average egg weight. The standard deviation of individual pullet's egg weights was moderately heritable and genetically correlated positively with egg weight characters and negatively with egg production; these estimates were consistent with the responses to selection for reduced egg weight variability observed elsewhere

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Selection for Egg Mass in the Domestic Fowl

Poultry Science ◽

10.3382/ps.0601115 ◽

1981 ◽

Vol 60 (6) ◽

pp. 1115-1122 ◽

Cited By ~ 7

Author(s):

H.L. MARKS

Keyword(s):

Domestic Fowl ◽

Egg Mass ◽

Selection For

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Effect of sampling errors on efficiency of selection indices. 2. Use of information on associated traits for improvement of a single important trait

Animal Science ◽

10.1017/s0003356100031020 ◽

1976 ◽

Vol 23 (1) ◽

pp. 1-14 ◽

Cited By ~ 53

Author(s):

Jill Sales ◽

W. G. Hill

Keyword(s):

Selection Index ◽

Heritability Estimate ◽

Parameter Estimates ◽

Response To Selection ◽

Sampling Errors ◽

Estimation Of Parameters ◽

Selection Indices ◽

Important Trait ◽

Selection For ◽

Efficiency Of Selection

SUMMARYAn analysis is undertaken of the effect of errors in estimates of parameters on the response to selection for an economically important trait (trait 1) when one or more additional traits are added in a selection index. The detailed analysis is confined to one additional trait (trait 2) which contributes useful information unless the genetic and phenotypic regressions of trait 1 on trait 2 are equal.If there are errors in parameter estimates the extra response obtained by including trait 2 will usually be over-predicted. When trait 2 actually contributes no useful information the predicted benefit equals the real loss in efficiency from its inclusion.The loss in efficiency from poor estimation of parameters, whether or not the second trait makes a contribution, is roughly one-quarter of the squared coefficient of variation of a heritability estimate of trait 1 in the same experiment.

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Selection for increased egg mass under ahemeral light‐dark cycles

British Poultry Science ◽

10.1080/00071668608416886 ◽

1986 ◽

Vol 27 (2) ◽

pp. 339-344 ◽

Cited By ~ 2

Author(s):

W. H. Foster

Keyword(s):

Egg Mass ◽

Selection For

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Selection for Egg Mass in the Domestic Fowl

Poultry Science ◽

10.3382/ps.0601788 ◽

1981 ◽

Vol 60 (8) ◽

pp. 1788-1791

Author(s):

K.W. WASHBURN ◽

G.S. BRAH ◽

H.L. MARKS

Keyword(s):

Domestic Fowl ◽

Egg Mass ◽

Selection For

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BREEDING FOR FEED EFFICIENCY: POULTRY

Canadian Journal of Animal Science ◽

10.4141/cjas84-062 ◽

1984 ◽

Vol 64 (3) ◽

pp. 513-527 ◽

Cited By ~ 23

Author(s):

R. W. FAIRFULL ◽

J. R. CHAMBERS

Keyword(s):

Body Weight ◽

Body Fat ◽

Feed Efficiency ◽

Body Weight Gain ◽

Feed Consumption ◽

Direct Selection ◽

Egg Mass ◽

Economic Traits ◽

Management Techniques ◽

Selection For

In egg-type poultry, variation in egg mass, body weight and change in body weight account for about 50–70% of the variation in feed consumed. In meat-type poultry, about 40% of the variation in feed consumption is attributable to variation in change of body weight (gain), and body weight itself. Past selection, primarily for egg numbers and egg size (egg mass) in egg stocks and for gain in meat stocks, has resulted in a correlated improvement in feed efficiency. Heterosis from breed or strain crosses contributes an average of 6% to improvement of feed efficiency in both egg and meat stocks. The success of direct selection for feed efficiency depends upon variation in feed consumption not attributable to economic traits in present poultry selection programs. There is evidence that such variation exists which could be successfully exploited in poultry. In egg stocks, the evidence is mainly from studies of variation within and between strains. In meat stocks, there is evidence from uni-trait selection studies as well as studies of within and between strain variation. The degree to which such selection would be successful in a multi-trait selection program and the economic viability of such success as compared to alternatives needs to be determined. Improvement of feed efficiency is possible by reducing feed requirements for maintenance and activity, by reducing behaviors causing feed wastage, or by reducing body fat to require less feed energy per unit gain. Feed wastage can be reduced by management techniques. Thus, the exploitation of feed-wasting behavior is not presently necessary. The best prospects are those associated with maintenance energy requirements in both egg and meat stocks of poultry, and the reduction of body fat in meat stocks. It is improbable that the opportunities for breeding to improve feed efficiency have been exhausted, much less identified. Key words: Breeding, feed efficiency, poultry, selection

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Social interactions within the family enhance the capacity for evolutionary change

10.1101/115014 ◽

2017 ◽

Author(s):

BJM Jarrett ◽

M Schrader ◽

D Rebar ◽

TM Houslay ◽

RM Kilner

Keyword(s):

Social Interactions ◽

Social Environments ◽

The Social ◽

The Family ◽

Selection Experiments ◽

Nicrophorus Vespilloides ◽

Classical Models ◽

In The Wild ◽

Selection For ◽

Provision Of Care

AbstractClassical models of evolution seldom predict evolution in the wild. One explanation is that the social environment has important, yet overlooked, effects on how traits change in response to natural selection. We tested this idea with selection experiments on burying beetles (Nicrophorus vespilloides), sub-social insects that exhibit biparental care. Populations responded to selection for larger adults only when parents cared for their offspring, and responded to selection for smaller adults only when we prevented parents from providing care. Comparative analyses revealed a similar pattern: evolutionary increases in species size within the genus Nicrophorus are associated with the obligate provision of care. Synthesising our results with previous studies, we suggest that cooperative social environments enhance the response to selection whereas conflict can prevent further directional selection.

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