MASS SELECTION FOR POST-WEANING GROWTH IN SWINE: I. THE VALUE OF A PEDIGREED CONTROL POPULATION

1971 ◽  
Vol 51 (2) ◽  
pp. 481-496 ◽  
Author(s):  
G. W. RAHNEFELD
Keyword(s):  
Additive Genetic Variance ◽  
Breeding Population ◽  
Control Population ◽  
Mass Selection ◽  
Selection For ◽  
Average Size ◽  
Genetic Value ◽  
Seven Generations ◽  
Two Populations ◽  
Made In

A pedigreed control population of Yorkshire swine has been described. The average size of the breeding population was 20 males and 40 females in each of the seven generations. The effective number of parents per generation was estimated at 87.5. There has been little or no evidence of any significant changes in the genetic value of the population over the seven generations as determined by estimates of additive genetic variance, selection differentials, and other related parameters. The performance of the control population was compared with that of a selected population and with crossbreds produced by mating select population males to control population females. Comparisons were made in the same environments. The comparisons of the effects of the selection program on several traits measured in the two populations have been made, based on the absolute trends in these populations over the seven generations and as a deviation from the performance of the control population.

MASS SELECTION FOR POST-WEANING GROWTH IN SWINE. IV. SELECTION RESPONSE AND CONTROL POPULATION STABILITY

1976 ◽  
Vol 56 (4) ◽  
pp. 783-790
Author(s):  
G. W. RAHNEFELD ◽  
I. GARNETT
Keyword(s):  
Additive Genetic Variance ◽  
Average Daily Gain ◽  
Selection Response ◽  
Relative Magnitude ◽  
Control Population ◽  
Mass Selection ◽  
Gene Effects ◽  
Selection For ◽  
And Control ◽  
Daily Gain

Recurrent mass selection for post-weaning average daily gain was practiced for 11 generations in a population of Lacombe swine. Response to selection was assessed from predicted response, 0.241 ± 0.023 kg; observed response, 0.146 ± 0.018 kg; estimated heritability, 0.327 ± 0.031; and realized heritability, 0.198 ± 0.016. Observed response was estimated to be 0.61 of the predicted. Examination of additive genetic variance, selection differentials, drift variance, inbreeding and regression of post-weaning average daily gain on generation time indicated that the pedigreed Yorkshire control population served as an adequate control. Gene effects were not found to be dependent on the sex of the organism as assessed by the genetic correlation between sexes, covariance between half-sib family means and the relative magnitude of parent–offspring-based estimates of heritability.

scholarly journals MASS SELECTION FOR POST-WEANING GROWTH IN SWINE: II. RESPONSE TO SELECTION

1971 ◽  
Vol 51 (2) ◽  
pp. 497-502 ◽  
Author(s):  
G. W. RAHNEFELD
Keyword(s):  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Average Daily Gain ◽  
Mass Selection ◽  
Realized Heritability ◽  
Response To Selection ◽  
Components Of Variance ◽  
Selection For ◽  
Seven Generations ◽  
Daily Gain

Recurrent mass selection for post-weaning average daily gain was practiced for seven generations in a population of Lacombe swine. Response to selection was positive, but the observed response was estimated to be only 0.33 of the predicted. The pooled estimate of additive genetic variance was 0.0013 ± 0.0002. Realized heritability was 0.126 ± 0.029. The pooled estimate of heritability obtained from components of variance and parent-offspring regression was 0.377 ± 0.058. Litter size was positively correlated with average daily gain (0.14 piglet per generation). No significant effects of selection in reducing additive genetic variance were observed.

RESPONSE TO SELECTION FOR BODY WEIGHT OR FEED EFFICIENCY IN MICE TESTED ON CORN, RYE AND WHEAT DIETS

1986 ◽  
Vol 66 (2) ◽  
pp. 389-397
Author(s):  
R. I. McKAY ◽  
R. J. PARKER ◽  
W. GUENTER
Keyword(s):  
Body Weight ◽  
Feed Efficiency ◽  
Mass Selection ◽  
Response To Selection ◽  
Initial Weight ◽  
Commercial Diet ◽  
Final Weight ◽  
Dc Line ◽  
Selection For ◽  
Seven Generations

Mass selection for adjusted feed efficiency (AFE, g gain/g feed) and adjusted body weight (ABW, g) of male mice was practiced for seven generations on each of three diets: corn, rye and wheat. The three experimental diets, fed between 21 and 35 d, were isocaloric (approximately 16.5 MJ GE kg−1) and isonitrogenous (CP approximately 13%). A common commerical diet (PC) was fed at all other times. With each diet two control lines, randomly mated, were tested on either the experimental diets (DC) or a commercial diet (PC). Selection was based upon linear adjustment to a common initial weight (10 g) for either final weight (ABW) or feed efficiency (AFE) measured between 21 and 35 d of age. Response was determined as a deviation from the appropriate DC line. All animals were placed in specially designed individual cages during the test period. Half-sib estimates of heritability in the PC line were 0.13(± 0.11) for ABW and 0.19(± 0.10) for AFE. Half-sib estimates pooled across lines and diets were 0.16(± 0.07) for ABW and 0.28(± 0.07) for AFE. Realized heritabilities for ABW were 0.24(± 0.06), 0.06(± 0.07) and 0.14(± 0.06) for the corn, rye and wheat diets, respectively. Response to selection for AFE was poor with the highest heritability obtained on the wheat diet (h2 = 0.13 ± 0.02). Key words: Selection, mice, body weight, feed efficiency, diets

PREDICTIONS OF THE EFFECTIVENESS OF INTRAPOPULATION SELECTION VERSUS SELECTION FOR SPECIFIC COMBINING ABILITY IN SWINE

1984 ◽  
Vol 64 (4) ◽  
pp. 799-806
Author(s):  
R. M. McKAY ◽  
G. W. RAHNEFELD
Keyword(s):  
Combining Ability ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Effective Means ◽  
Average Daily Gain ◽  
Mass Selection ◽  
Genetic Covariance ◽  
Selection For ◽  
Sib Selection ◽  
Daily Gain

Additive genetic variance estimates for purebred (Lacombe) and crossbred (Lacombe × Yorkshire) populations and the additive genetic covariance between purebred and crossbred progeny were calculated for postweaning average daily gain, total probe fat, total carcass fat, and litter size in swine. These estimates were used to predict the effectiveness of four methods of intrapopulation selection (IP) relative to selection for specific combining ability (SCA) to determine the most effective means of improving crossbred performance. The intrapopulation methods were mass selection based on information from both sexes (BS), mass selection based on information from one sex (OS), full-sib selection (FS), and half-sib selection (HS). The Lacombe population was selected over 12 generations for increased postweaning average daily gain and the Lacombe × Yorkshire population was generated by breeding Lacombe boars with randomly selected gilts from a Yorkshire control population. Selection for combining ability was the most effective means of improving average daily gain except when information was available on both sexes and the relative selection intensity (SCA/IP) was less than 0.60. Mass selection was superior to SCA for improving total probe fat except when information was restricted to one sex and the relative selection intensity was less than 0.47. For total probe fat and total carcass fat, SCA was superior to FS and HS for relative selection intensities less than 0.65 and 0.74, respectively. Selection for combining ability was superior to OS for litter size regardless of the generation interval length. Key words: Intrapopulation selection, selection for combining ability, additive genetic variance, additive genetic covariance, swine

SELECTION FOR OLEIC, LINOLEIC AND LINOLENIC ACID CONTENT IN F2 POPULATIONS OF RAPE

1976 ◽  
Vol 56 (4) ◽  
pp. 961-966 ◽  
Author(s):  
Z. P. KONDRA ◽  
T. W. WILSON
Keyword(s):  
Linolenic Acid ◽  
Acid Content ◽  
Seed Oil ◽  
Linoleic Acid Content ◽  
Linolenic Acid Content ◽  
Brassica Napus L ◽  
Selection For ◽  
Lower Magnitude ◽  
Two Populations ◽  
Made In

Single plant selections for high, intermediate, and low oleic, linoleic and linolenic acid content of rapeseed (Brassica napus L.) oil were made in the F2 generation of three crosses. The three parent strains produced seed oil practically free of eicosenoic and erucic acids and differed in oleic, linoleic and linolenic acid content. The F3 and F4 progeny were analyzed for fatty acid composition. Selection for low and high values of oleic and linoleic acid content was reasonably successful in two out of three crosses. Selection for extremes of linolenic acid content was unsuccessful in all three crosses. Regression analyses indicated high heritabilities for oleic and linoleic acids in two of three crosses but low heritabilities for linolenic acid in all three crosses. Correlations between oleic versus linoleic and oleic versus linolenic were negative and highly significant. Correlations between linoleic versus linolenic were of lower magnitude but positive and significant in all but two populations.

scholarly journals Genetic Variation and Selection for Carotene Content in Carrots

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 821E-821
Author(s):  
Philipp Simon
Keyword(s):  
Genetic Variation ◽  
Combining Ability ◽  
General Combining Ability ◽  
Mass Selection ◽  
Realized Heritability ◽  
Response To Selection ◽  
Carotene Content ◽  
Selection For ◽  
Variation And Selection ◽  
Made In

A six-parent diallel which included carrot inbreds with a range of carotene content from 80 to 490 ppm was evaluated over 2 years. General combining ability accounted for most of the variation observed. Phenotypic mass selection was exercised for high carotene content in three carrot populations. Response to selection continued to be high in one population, HCM, after 11 cycles of selection. In contrast, after three generations of selection, little progress was able to be made in a population derived from primarily Nantes-type open-pollinated cultivars. Realized heritability estimates varied from 15% to 49%. Environment contributed significantly to variation in carotene content.

scholarly journals Quantitative variation in the tropical maize population, ESALQ-PB1

2008 ◽  
Vol 65 (2) ◽  
pp. 174-182 ◽  
Author(s):  
João Antonio da Costa Andrade ◽  
José Branco de Miranda Filho
Keyword(s):  
Plant Height ◽  
Additive Genetic Variance ◽  
Correlation Coefficients ◽  
Breeding Population ◽  
Mass Selection ◽  
Branch Number ◽  
Maize Population ◽  
Expected Gain ◽  
Ear Height ◽  
One Year

Good yield and intermediate plant height, ear height, and tassel size characterize the maize population ESALQ-PB1 as an outstanding breeding population. Estimates of genetic parameters are reported for 13 traits: plant height (PH), ear height (EH), ear placement (EP), tassel length (TL), tassel weight (TW), tassel branch number (TB), ear weight (EW), total grain weight (GW), ear length (EL), ear diameter (ED), kernel row number (RN), kernel number per row (KR) and prolificacy (PR). Results refer to one location and one year. Genetic variation was detected for all traits, and the estimates of the additive genetic variance are presented. The coefficients of heritability (individual basis) varied from 0.14 to 0.72 and were considered high for PH, EH and TB; intermediate for EP, TL, TW, EL, EP, ED and RN, and low for EW, GW, KR and PR. The coefficient of heritability (progeny mean basis) showed approximately the same trend and varied from 0.40 to 0.75. The highest expected gain from selection was for TB (27% per cycle) under mass selection and for TW (16.4%) under progeny selection; the lowest expected gain was for ED either for mass selection (1.9%) or progeny selection (2.9%). Additive correlation coefficients (rA) of 0.5<rA<0.6 were found for PH or EH and yield traits (EW and GW) and its components EL and KR, and 0.10<rA<0.44 for PH or EH and tassel traits. For the tassel traits the highest correlation was rA = 0.63 (TB.TW). EP was positively correlated with TB, TW, PH, EH and PR; and negatively correlated with ED and RN. The expected correlated responses in several traits after selection for GW, EH and TB are given.

Comparing Genetic Variation within Red Winter Wheat Populations with and without Image-Based Optical Sorter Selection

2019 ◽  
Vol 9 (2) ◽  
pp. 266-277
Author(s):  
Hussein M. Khaeim ◽  
Anthony Clark ◽  
Tom Pearson ◽  
Dr. David Van Sanford
Keyword(s):  
Genetic Variation ◽  
Fusarium Head Blight ◽  
Heading Date ◽  
Fusarium Head Blight Resistance ◽  
Gibberella Zeae ◽  
Mass Selection ◽  
Head Blight ◽  
Red Winter Wheat ◽  
Two Populations ◽  
Head Scab

Head scab is historically a devastating disease affecting not just all classes of wheat but also barley and other small grains around the world. Fusarium head blight (FHB), or head scab, is caused most often by Fusarium graminearum (Schwabe), (sexual stage – Gibberella zeae) although several Fusarium spp. can cause the disease. This study was conducted to determine the effect of mass selection for FHB resistance using an image-based optical sorter. lines were derived from the C0 and C2 of two populations to compare genetic variation within populations with and without sorter selection. Our overall hypothesis is that sorting grain results in improved Fusarium head blight resistance. Both of the used wheat derived line populations have genetic variation, and population 1 has more than population 17. They are significantly different from each other for fusarium damged kernel (FDK), deoxynivalenol (DON), and other FHB traits. Although both populations are suitable to be grown for bulks, population 1 seems better since it has more genetic variation as well as lower FDK and DON, and earlier heading date. Lines within each population were significantly different and some lines in each population had significantly lower FDK and DON after selection using an optical sorter. Some lines had significant reduction in both FDK and DON, and some others had either FDK or DON reduction. Lines of population 1 that had significant reduction, were more numerous than in population 17, and FDK and DON reduction were greater.

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