scholarly journals Two-way selection for body weight in Tribolium on two levels of nutrition

1967 ◽  
Vol 9 (3) ◽  
pp. 309-330 ◽  
Author(s):  
R. T. Hardin ◽  
A. E. Bell
Keyword(s):  
Genetic Correlation ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Minimum Size ◽  
Direct Selection ◽  
Correlated Responses ◽  
Larval Weight ◽  
Large Size ◽  
Selection For ◽  
Selection Differentials

Parameters necessary for predicting direct and correlated responses for large and small 13-day larval weight in T. castaneum on two levels of nutrition were estimated in the base population. Larval weight in the GOOD environment was approximately twice that observed in POOR. Heritabilities (estimated from the ratio of sire component to total phenotype variance) of larval weight on the two rations were similar, 0·21 ± 0·06 and 0·19 ± 0·05 for GOOD and POOR, respectively. Heritabilities based on dam-offspring covariances were similar to these, but those obtained from full-sib covariances were much larger (0·97 ± 0·07 for GOOD and 0·69 ± 0·07 for POOR). This suggested that considerable dominance rather than maternal effects were present. The genetic correlation between growth on GOOD and growth on POOR was estimated as + 0·60 ± 0·21.The selection experiment was replicated four times with each replication extending over eight generations. Good agreement between predicted and observed values for direct selection was observed for large selection in both environments and small selection in POOR. However, response to small selection in GOOD was significantly greater than predicted in all four replications and was associated with increased selection differentials. Realized heritabilities were approximately the same for both directions in GOOD yet asymmetrical responses occurred for all replications due to unequal selection differentials. On the other hand, realized heritabilities were asymmetrical in POOR. Those observed for small selection were more than twice the size of those calculated for large lines. However, the responses in POOR were symmetrical since the selection differentials varied inversely with the realized heritabilities.Because of the asymmetry observed for heritabilities and selection differentials, correlated responses were poorly predicted. The average effective genetic correlation between growth in GOOD and growth in the POOR environment agreed remarkably well with the base estimate, yet asymmetry of the genetic correlation was a consistent phenomenon with values for the large lines being less than the base parameter while small lines were uniformly larger.Asymmetries of the various genetic parameters were not anticipated from base estimates. They were not caused by sampling or chance fluctuations since all four replications were remarkably consistent. Asymmetry for any one genetic parameter (e.g. heritability) was associated with a particular environment or direction of selection while other genetic parameters reacted asymmetrically in populations exposed to a different set of environmental treatments.For maximum performance in a single environment, these results show that selection should be practiced in that environment. With regard to mean performance in GOOD and POOR environments, selection for large size in POOR gave some 25% more gain than selection in GOOD. Selection for small size in either environment was equally effective in obtaining minimum size in both environments.

RELATIVE MERIT OF SIB VERSUS OWN PERFORMANCE IN SELECTION FOR LEAN MEAT PRODUCTION IN SWINE

1967 ◽  
Vol 47 (3) ◽  
pp. 171-179 ◽  
Author(s):  
A. H. Martin ◽  
H. T. Fredeen
Keyword(s):  
Genetic Correlation ◽  
Population Size ◽  
Genetic Parameters ◽  
Selection Procedure ◽  
Indirect Selection ◽  
Direct Selection ◽  
Meat Production ◽  
Population Sizes ◽  
Selection For ◽  
Selection Intensities

The relative selection efficiency (RSE) of direct selection for a trait of basic interest and indirect selection on an alternate trait was examined with consideration given to several population sizes, selection intensities and genetic parameters. Slaughter of litter samples resulting in a reduction of the population available for selection was associated with the direct but not the indirect selection procedure. Values of RSE increased with increasing values of the genetic correlation, but for any given value of the genetic correlation, RSE was inversely related to the heritability of the basic trait. Population size was important only for herds comprising fewer than 10 breeding females.Using predicted percent yield of lean cuts, (A), as the trait for direct selection with [Formula: see text] of 0.2, 0.3 and 0.4 and the live back fat probe, (B), as the trait for indirect selection, with [Formula: see text] and assuming a genetic correlaton between A and B of 0.6, it was demonstrated that, respectively 38, 19 and 9% faster genetic gains in the basic trait accrued from indirect as compared with direct selection. It is suggested that the inherent reduction in population size, coupled with other practical aspects associated with carcass testing, might make the indirect selection method preferable even when RSE is less than unity.

scholarly journals Realized Sampling Variances of Estimates of Genetic Parameters and the Difference Between Genetic and Phenotypic Correlations

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1409-1416 ◽  
Author(s):  
Kenneth R Koots ◽  
John P Gibson
Keyword(s):  
Genetic Correlation ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Phenotypic Correlation ◽  
Parameter Estimates ◽  
Sampling Variance ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates

Abstract A data set of 1572 heritability estimates and 1015 pairs of genetic and phenotypic correlation estimates, constructed from a survey of published beef cattle genetic parameter estimates, provided a rare opportunity to study realized sampling variances of genetic parameter estimates. The distribution of both heritability estimates and genetic correlation estimates, when plotted against estimated accuracy, was consistent with random error variance being some three times the sampling variance predicted from standard formulae. This result was consistent with the observation that the variance of estimates of heritabilities and genetic correlations between populations were about four times the predicted sampling variance, suggesting few real differences in genetic parameters between populations. Except where there was a strong biological or statistical expectation of a difference, there was little evidence for differences between genetic and phenotypic correlations for most trait combinations or for differences in genetic correlations between populations. These results suggest that, even for controlled populations, estimating genetic parameters specific to a given population is less useful than commonly believed. A serendipitous discovery was that, in the standard formula for theoretical standard error of a genetic correlation estimate, the heritabilities refer to the estimated values and not, as seems generally assumed, the true population values.

Selection for rate and efficiency of lean gain in Hereford cattle 1. Selection pressure applied and direct responses

1990 ◽  
Vol 51 (1) ◽  
pp. 23-34 ◽  
Author(s):  
R. A. Mrode ◽  
C. Smith ◽  
R. Thompson
Keyword(s):  
Genetic Parameters ◽  
Control Line ◽  
Correlated Responses ◽  
Direct Response ◽  
Lean Growth ◽  
Hereford Cattle ◽  
Frozen Semen ◽  
Phenotypic Standard Deviation ◽  
Selection For ◽  
Selection Of

ABSTRACTSelection of bulls for rate and efficiency of lean gain was studied in a herd of Hereford cattle. There were two selection lines, one selected for lean growth rate (LGR) from birth to 400 days and the other for lean food conversion ratio (LFCR) from 200 to 400 days of age, for a period of 8 years. A control line bred by frozen semen from foundation bulls was also maintained. Generation interval was about 2·4 years and average male selection differentials, per generation were 1·2 and — 1·1 phenotypic standard deviation units for LGR and LFCR respectively.Genetic parameters and responses to selection were estimated from the deviation of the selected lines from a control line and by restricted maximum likelihood (REML) techniques on the same material. Realized heritabilities were 0·40 (s.e. 0·12) for LGR and 0·40 (s.e. 0·13) for LFCR using the control line. Corresponding estimates from REML were 0·42 (s.e. 0·10) and 0·37 (s.e. 0·14). The estimate of the genetic correlation between LGR and LFCR was about — 0·69 (s.e. 0·12) using REML.The estimates of direct annual genetic change using deviations from the control were 3·6 (s.e. 1·3) g/day for LGR and — 0·14 (s.e. 0·07) kg food per kg lean gain for LFCR. Corrsponding estimates from REML were similar but more precisely estimated. The correlated responses for LFCR in the LGR line was higher than the direct response for LFCR.

scholarly journals PSVIII-38 Late-Breaking Abstract: Estimating genetic parameters of feed efficiency traits in American mink

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 347-347
Author(s):  
Pourya Davoudi ◽  
Duy Ngoc Do ◽  
Guoyu Hu ◽  
Siavash Salek Ardestani ◽  
Younes Miar
Keyword(s):  
Body Weight ◽  
Genetic Correlation ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
American Mink ◽  
Genetic Correlations ◽  
Final Body Weight ◽  
Selection For

Abstract Feed cost is the major input cost in the mink industry and thus improvement of feed efficiency through selection for high feed efficient mink is necessary for the mink farmers. The objective of this study was to estimate the heritability, phenotypic and genetic correlations for different feed efficiency measures, including final body weight (FBW), daily feed intake (DFI), average daily gain (ADG), feed conversion ratio (FCR) and residual feed intake (RFI). For this purpose, 1,088 American mink from the Canadian Center for Fur Animal Research at Dalhousie Faculty of Agriculture were recorded for daily feed intake and body weight from August 1 to November 14 in 2018 and 2019. The univariate models were used to test the significance of sex, birth year and color as fixed effects, and dam as a random effect. Genetic parameters were estimated via bivariate models using ASReml-R version 4. Estimates of heritabilities (±SE) were 0.41±0.10, 0.37±0.11, 0.33±0.14, 0.24±0.09 and 0.22±0.09 for FBW, DFI, ADG, FCR and RFI, respectively. The genetic correlation (±SE) was moderate to high between FCR and RFI (0.68±0.15) and between FCR and ADG (-0.86±0.06). In addition, RFI had low non-significant (P > 0.05) genetic correlations with ADG (0.04 ± 0.26) and BW (0.16 ± 0.24) but significant (P < 0.05) high genetic correlation with DFI (0.74 ± 0.11) indicating that selection for lower RFI will reduce feed intake without adverse effects on the animal size and growth rate. The results suggested that RFI can be implemented in genetic/genomic selection programs to reduce feed intake in the mink production system.

Genetic parameter estimations and genomic insights for teat and udder structure in young and mature Canadian Angus cows

2021 ◽  
Author(s):  
K Devani ◽  
J J Crowley ◽  
G Plastow ◽  
K Orsel ◽  
T S Valente
Keyword(s):  
Animal Model ◽  
Genetic Correlation ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Age Groups ◽  
Morbidity And Mortality ◽  
Parameter Estimations ◽  
Angus Cattle ◽  
Genetic Evaluations

Abstract Poor teat and udder structure, frequently associated with older cows, impact cow production and health, as well as calf morbidity and mortality. However, producer culling, for reasons including age, production, feed availability, and beef markets, creates a bias in teat and udder scores assessed and submitted to the Canadian Angus Association for genetic evaluations towards improved mammary structure. In addition, due to the infancy of the reporting program, repeated scores are rare. Prior to adoption of genetic evaluations for teat and udder scores in Canadian Angus cattle, it is imperative to verify that teat and udder scores from young cows are the same trait as teat and udder scores estimated on mature cows. Genetic parameters for teat and udder scores from all cows (n=4,192), and then from young cows (parity 1 and 2) and from mature cows (parity ≥ 4) were estimated using a single trait animal model. Genetic correlations for the traits between the two cow age groups were estimated using a two-trait animal model. Estimates of heritability (PSD) were 0.32 (0.07) and 0.45 (0.07) for young teat and udder score, and 0.27 (0.07) and 0.31 (0.07) for mature teat and udder score, respectively. Genetic correlation (PSD) between the young and mature traits was 0.87 (0.13) for teat score and 0.40 (0.17) for udder score. GWAS were used to further explore the genetic and biological commonalities and differences between the two groups. Although there were no genes in common for the two udder scores, 12 genes overlapped for teat score in the two cow age groups. Interestingly, there were also 23 genes in common between teat and udder scores in mature cows. Based on these findings, it is recommended that producers collect teat and udder score on their cow herd annually.

INHERITANCE OF WEIGHTS OF LAMBS REARED ARTIFICIALLY OR WITH THEIR DAMS

1983 ◽  
Vol 63 (2) ◽  
pp. 263-268 ◽  
Author(s):  
J. N. B. SHRESTHA ◽  
H. F. PETERS ◽  
D. P. HEANEY
Keyword(s):  
Genetic Correlation ◽  
Direct Selection ◽  
Milk Replacer ◽  
Response To Selection ◽  
Genetic Response ◽  
Artificial Rearing ◽  
Solid Diet ◽  
Selection For ◽  
Heritability Estimates ◽  
Age Estimates

This study involved 250 lambs reared artificially with milk replacer and solid diet from 2 to 70 days and 316 lambs creep-fed solid diet and reared with their dams from birth to 70 days. Thereafter, all lambs were retained on solid diet to 140 days of age. Heritability estimates for weights of lambs reared artificially tended to be larger than the corresponding estimates for lambs reared with their dams (P > 0.05). Phenotypic variances of lambs reared with their dams were larger at birth and at 35 days, whereas lambs reared artificially had larger phenotypic variances at 70 and 140 days of age. Estimates of genetic correlation between half-sib family means of lambs reared artificially with corresponding half-sibs reared with their dams ranged from 0.15 to 0.91, suggesting the absence of sire × rearing system interaction. We conclude that greater genetic response to selection for lamb weights at various ages could be achieved from direct selection among lambs reared artificially compared to those reared with their dams. However, in the absence of artificial rearing, prospective breeding stock reared with their dams should be tested for postweaning performance to permit full expression of transmitted sire differences. Key words: Sheep, lamb rearing, heritability estimates, genetic correlation

Genetic parameters for egg weight v. age curve, and other egg production and egg weight traits, in synthetic lines of chickens

1983 ◽  
Vol 34 (1) ◽  
pp. 85 ◽  
Author(s):  
BH Yoo ◽  
BL Sheldon ◽  
RN Podger
Keyword(s):  
Standard Deviation ◽  
Genetic Correlation ◽  
Egg Production ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Egg Mass ◽  
Control Line ◽  
Egg Weight ◽  
Egg Number ◽  
Selection For

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

scholarly journals Selection for ovulation rate in rabbits: Genetic parameters and correlated responses on survival rates1

2012 ◽  
Vol 90 (2) ◽  
pp. 439-446 ◽  
Author(s):  
P. Laborda ◽  
M. L. Mocé ◽  
A. Blasco ◽  
M. A. Santacreu
Keyword(s):  
Genetic Parameters ◽  
Ovulation Rate ◽  
Correlated Responses ◽  
Selection For

EFFECT OF SELECTION ON FEED UTILIZATION AND CARCASS SCORE EN SWINE

1970 ◽  
Vol 50 (3) ◽  
pp. 575-584 ◽  
Author(s):  
C. BERNARD ◽  
M. H. FAHMY
Keyword(s):  
Body Weight ◽  
Genetic Correlation ◽  
Genetic Improvement ◽  
Body Weight Gain ◽  
Feed Utilization ◽  
Phenotypic Correlation ◽  
Population Selection ◽  
Yorkshire Pigs ◽  
Selection For ◽  
Selection Differentials

Selection for feed utilization (FU) and carcass score (CS) based on full sib performance was practiced within three lines of Yorkshire pigs during ten generations. Line 1 was selected solely for FU, line 2 for CS and line 3 for the two traits combined in an index. Line 2 served as a control for lines 1 and 3 in FU and line 1 as a control for lines 2 and 3 in CS. Feed utilization was expressed as the amount of feed required per kilogram body weight gain. Carcass score was based on length, backfat thickness, loin eye area and belly grade measured on pigs marketed at 90 kg liveweight. Selection differentials for FU averaged 0.198 and 0.208 kg per generation for lines 1 and 3, respectively, while CS differentials were 7.2 and 7.4 points per generation for lines 2 and 3, respectively. Heritability estimates based on full sib performance and converted to individual bases were 0.16 for FU and 0.43 for CS. The phenotypic correlation between the two traits was −0.25 and the genetic correlation −0.55. Responses to selection for FU were 0.09 and 0.24 kg per generation for lines 1 and 3, respectively, while for CS they were 0.77 and 0.97 points for lines 2 and 3, respectively. Compared with the parental means, this represented a genetic improvement of 0.25 and 0.66% per generation for FU in lines 1 and 3, and 1.06 and 1.33% per generation for CS in lines 2 and 3, respectively. The realized responses in lines 1 and 3 to selection for FU Were 58 and 148% of the expectation, and 58 and 72% for lines 2 and 3 in CS. Due to larger selection differentials in line 3, along with a strong positive genetic correlation between the two traits observed in this particular population, selection for the combined traits was 1.35 and 1.10% more effective in improving FU and CS, respectively, than selection for these traits individually.

scholarly journals Heritability and Correlations Among Popping Characteristics and Seed Weight in a Broad-based Temperate-adapted Nuña Bean (Phaseolus vulgaris L.) Population

HortScience ◽  
2009 ◽  
Vol 44 (1) ◽  
pp. 214-216 ◽  
Author(s):  
Jesse Vorwald ◽  
James Nienhuis
Keyword(s):  
Phaseolus Vulgaris ◽  
South America ◽  
Seed Weight ◽  
Genetic Parameters ◽  
Unique Property ◽  
Direct Selection ◽  
Phaseolus Vulgaris L ◽  
Selection For ◽  
Photoperiod Sensitive ◽  
Seed Characteristics

Nuña beans are a type of common bean (Phaseolus vulgaris L.) from the Andean region of South America that possess the unique property of popping. To develop temperate-adapted nuña bean cultivars, knowledge is needed regarding the inheritance and relationships among popping characteristics and seed weight. Nuña bean landraces are often photoperiod-sensitive; thus, to obtain estimates of the genetic parameters associated with seed characteristics, populations adapted to the long days of northern temperate climates were developed. Four sets of 10 families, sampled from a temperate-adapted population, were crossed in a Design II mating design. The heritabilities of seed weight, popping percentage, and the coefficient of expansion were relatively high, 0.77 ± 0.04, 0.87 ± 0.07, and 0.74 ± 0.09, respectively. Large positive phenotypic (0.773) and additive genetic (0.539) correlations were observed between popping percentage and the coefficient of expansion. Correlations with seed weight were not significant. The results indicate that direct selection for either increased popping percentage or coefficient of expansion will simultaneously improve both traits with little or no change in seed weight.

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