Preweaning losses of piglets as a result of index selection for reduced backfat thickness and increased growth rate

1993 ◽  
Vol 73 (2) ◽  
pp. 437-442 ◽  
Author(s):  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Selection Index ◽  
Backfat Thickness ◽  
Index Selection ◽  
Selection For ◽  
Preweaning Period

Index selection for reduced backfat thickness and increased postweaning growth rate resulted in increased preweaning death losses due either directly or indirectly to the sow in the Yorkshire and Hampshire breeds. This resulted in a reduced percentage of piglets weaned in the Yorkshire breed. Key words: Swine, selection index, preweaning period, mortality, survival

Effect of index selection for reduced backfat thickness and increased growth rate on sow weight changes through two parities in swine

1992 ◽  
Vol 72 (2) ◽  
pp. 403-408 ◽  
Author(s):  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Selection Pressure ◽  
Backfat Thickness ◽  
Index Selection ◽  
Weight Changes ◽  
Selection For ◽  
The Impact

The impact of continued selection for reduced backfat thickness and improved growth rate on weight changes in Yorkshire and Hampshire sows, from breeding as gilts to weaning their second litter, was studied. Results suggest that some sow weight changes may have been influenced by selection pressure exerted. Key words: Sows, Canadian Yorkshire, Hampshire, liveweight change

RESPONSES TO INDEX SELECTION FOR REDUCED BACKFAT THICKNESS AND INCREASED GROWTH RATE IN SWINE

1990 ◽  
Vol 70 (3) ◽  
pp. 973-977 ◽  
Author(s):  
R. M. McKAY
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Average Daily Gain ◽  
Selection Response ◽  
Backfat Thickness ◽  
Index Selection ◽  
Selection Differential ◽  
Differential Selection ◽  
Selection For ◽  
Daily Gain

Selection resulted in a decrease in probed backfat thickness and a negligible change in postweaning average daily gain. Realized heritabilities in the Yorkshire and Hampshire select lines were 0.41 ± 0.04 and 0.34 ± 0.18, respectively, for probed backfat thickness and 0.38 ± 0.43 and 0.65 ± 0.19, respectively, for postweaning average daily gain. Key words: Swine, selection differential, selection response, backfat, growth rate

Carcass quality characteristics of swine selected for reduced backfat thickness and increased growth rate

1993 ◽  
Vol 73 (3) ◽  
pp. 483-494 ◽  
Author(s):  
R. L. Cliplef ◽  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Subcutaneous Fat ◽  
Quality Characteristics ◽  
Backfat Thickness ◽  
Carcass Quality ◽  
Growth Selection ◽  
Selection For ◽  
Seven Generations

Selection for reduced backfat thickness and increased growth rate in Yorkshire (eight generations) and Hampshire (seven generations) swine resulted not only in less backfat but carcasses which were longer with higher percentages of dissectible lean in the fresh hams. Selected carcasses also had a higher incidence of more severe loin lean-fat separation and subjectively perceived softness in the subcutaneous fat. Boar carcasses were longer and leaner with smaller loin eye areas compared with gilt carcasses. Key words: Swine, carcass quality, backfat, growth, selection

scholarly journals A Canonical Correlation Analysis of Relationships Between Growth, Compositional Traits and Longevity, Lifetime Productivity and Efficiency in Polish Landrace Sows

2014 ◽  
Vol 14 (2) ◽  
pp. 257-270 ◽  
Author(s):  
Magdalena Sobczyńska ◽  
Tadeusz Blicharski ◽  
Mirosław Tyra
Keyword(s):  
Growth Rate ◽  
Correlation Analysis ◽  
Canonical Correlation Analysis ◽  
Canonical Correlation ◽  
Performance Test ◽  
Selection Index ◽  
Phenotypic Selection ◽  
Backfat Thickness ◽  
Canonical Variate ◽  
Weaned Piglets

Abstract Relationships between performance test traits (growth rate, backfat thickness, loin depth, lean meat percentage, exterior, phenotypic selection index) and longevity traits (length of productive life, number of litters, total number of weaned pigs, number of weaned piglets per year, number of litters per year) in Landrace sows were evaluated using canonical correlation analysis. The data set consisted of 23,012 purebred sows that farrowed from 1994 to 2011 in 161 herds. The first three canonical correlations (0.37, 0.25, 0.07) were highly significant (P<0.0001). Correlations of the first canonical variate with the original measured variables indicated that sows with high values for this variate had lower growth rate (r=-0.31) and loin depth (r=-0.43), greater backfat thickness (r=0.23), as well as being older at birth of their last litter (r=0.98). These sows also had a greater number of litters (r=0.94) and better lifetime efficiency (r=0.61 and r=0.70 for number of weaned piglets per year and number of litters per year, respectively). Canonical loadings for the second canonical function indicate that sows with high values for the second set of variates had high growth rate (r=0.79) and phenotypic selection index (r=0.83), excellent conformation (r=0.62), as well as better efficiency in pig production (r=0.67). The squared multiple correlations show that the first canonical variate of the performance traits is a poor predictor of longevity (0.13) and nearly useless for predicting efficiency traits (0.07). Performance test traits explain 11% of the variance in the variables of longevity and lifetime productivity, whereas dependent variables explain only 3% of the variance in performance test traits. The relationships between performance test data and subsequent lifetime productivity or longevity were significant and unfavourable but low for Polish Landrace population

Visceral organ weights of swine selected for reduced backfat thickness and increased growth rate

1993 ◽  
Vol 73 (1) ◽  
pp. 201-206 ◽  
Author(s):  
R. L. Cliplef ◽  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Backfat Thickness ◽  
Visceral Organ ◽  
Organ Weights ◽  
Liver And Kidney ◽  
Seven Generations

Eight generations of Yorkshire swine and seven generations of Hampshire swine, involving a total of 2300 animals of which 1350 were selected for reduced backfat thickness and increased growth rate, had concurrent increases in visceral organ weights (heart, lungs, spleen, liver and kidney). Implications are that this could amount to 0.4 kg less weight per carcass. Key words: Pigs, organs, selection, Yorkshire, Hampshire

scholarly journals COMPARISON OF TANDEM AND INDEX SELECTION IN THE MODIFIED PEDIGREE METHOD OF BREEDING SELF-POLLINATED SPECIES

1969 ◽  
Vol 49 (6) ◽  
pp. 773-781 ◽  
Author(s):  
J. Pesek ◽  
R. J. Baker
Keyword(s):  
Environmental Variability ◽  
Selection Index ◽  
Genetic Effects ◽  
Index Selection ◽  
Two Stage ◽  
Economic Values ◽  
Correlated Traits ◽  
Selection For

Two-stage tandem selection and index selection were simulated for the modified pedigree method of breeding self-pollinated crops. We assumed that two traits were negatively correlated due to repulsion linkages, and considered correlations ranging from 0.00 to −0.95 corresponding to linkage intensities of 0.50 to 0.05. Each trait was controlled by five different loci with equal genetic effects. Three levels of environmental variability were assumed. Economic values were set at 0.5, 1.0 and 1.5 for one trait and 1.0 for the other.Index selection was superior to tandem selection for all combinations of parameters simulated. The efficiency of tandem selection was increased substantially by selecting the most valuable trait first. The efficiency of index selection can be increased by more frequent estimation of selection index coefficients.We did not consider positively correlated traits.

Effects of selection for low backfat thickness in pigs on the sites of tissue deposition in the body

1983 ◽  
Vol 36 (3) ◽  
pp. 389-397 ◽  
Author(s):  
J. D. Wood ◽  
O. P. Whelehan ◽  
M. Ellis ◽  
W. C. Smith ◽  
R. Laird
Keyword(s):  
Selection Index ◽  
Subcutaneous Fat ◽  
Live Weight ◽  
Carcass Composition ◽  
The Body ◽  
Backfat Thickness ◽  
Selection For ◽  
The University ◽  
And Control ◽  
The Relationship

ABSTRACTThe effects of selection for low backfat thickness on tissue deposition in different body sites has been investigated in pigs. Eight castrated male and eight female pigs from each of the selection and control lines maintained at the University of Newcastle upon Tyne were used. One castrated male and one female from each line was killed at 15, 30, 45, 60, 75, 90, 105 and 120 kg live weight following ad libitum food consumption and fully dissected.There were only small effects of line on carcass composition, selected pigs having 120 g/kg more bone than controls at the mean side weight (P < 0·001) and 40 g/kg more lean (NS). At the same mean weight of subcutaneous fat, selected pigs had thinner backfat than controls (approximately 3 mm) over m. longissimus at the last rib and over the shoulder but not at the mid-rump or mid-back positions. There appears to have been a slight shift in the sites of fat deposition from above m. longissimus in the loin towards the mid-line and rump as a result of selection, even though mid-rump, C and K measurements were all included in the selection index. However, there was no difference between the lines in the weight distribution of subcutaneous fat between six regions and so these shifts must have been very localized. There was no difference between lines in the relationship between P2 fat thickness and proportion of lean in the side.The effects of selection on the sites of deposition within tissues other than subcutaneous fat were small. In particular there was no evidence that selection has caused relocation of body fat from subcutaneous to the other sites.

SELECTION FOR NURSING ABILITY AND ADULT WEIGHT IN MICE

Genetics ◽  
1978 ◽  
Vol 88 (4) ◽  
pp. 761-780
Author(s):  
J Nagai ◽  
E J Eisen ◽  
J A B Emsley ◽  
A J McAllister
Keyword(s):  
Body Weight ◽  
Selection Index ◽  
Genetic Correlations ◽  
Regression Coefficients ◽  
Index Selection ◽  
Single Pair ◽  
Adult Weight ◽  
Selection For ◽  
Possible Cause ◽  
Line Generation

ABSTRACT Three selection treatments were conducted for 12 generations in each of two base populations (P and Q): (1) increased nursing ability of the mother (n12), as measured by mean 12-day weight of eight young within a crossfostering set (MP and MQ lines), (2) increased adult (42-day) body weight of the offspring (w42) (WP and WQ lines), and (3) performance combining the two traits (n12 and w42) into a selection index (BP and BQ lines). Lines CP and CQ were maintained as unselected controls in each population. In each line-generation subclass, 92 single-pair matings were made and the offspring assigned to balanced crossfostering sets of four dams each. Regression coefficients of mean performance (in grams) on generations were 0.080 ±0.029 and 0.054 ± 0.031 for n12 in MP and MQ, and 0.680 ± 0.039 and 0.868 ± 0.051 for w42 in WP and WQ, respectively. The BP and BQ lines showed genetic gains in n12 (0.090 and 0.053, respectively) and w42 (0.576 and 0.696) intermediate between the performance of MP and WP, and MQ and WQ, respectively, except for n12 of BQ. Realized heritabilities for n12 were 0.16 ± 0.05 and 0.11 ± 0.06 and those for w42 were 0.40 ± 0.02 and 0.43 ± 0.03 for P and Q, respectively. The realized genetic correlations between n12 and w42 were 0.70 ± 0.07 and 0.73 ± 0.08 in P and Q, respectively. The ratios of the predicted to observed responses in MP, BP and BQ were 0.99, 1.03 and 0.89, respectively. However, the predicted and observed responses differed in MQ, WP and WQ; the ratios were 1.29, 0.65 and 0.65, respectively. The observed combined responses for n12 and w42 in the index lines (BP and BQ) were smaller than the optimum expected from index selection. A possible cause was that the estimated genetic correlations (0.22 ± 0.16 and -0.17 ± 0.16 for BP and BQ, respectively) and heritabilities (0.39 ± 0.03 and 0.28 ± 0.02, respectively) for w42 that were used to construct the selection index were smaller than the respective realized parameters.

AN APPLICATION OF INDEX SELECTION TO THE IMPROVEMENT OF SELF-POLLINATED SPECIES

1970 ◽  
Vol 50 (3) ◽  
pp. 267-276 ◽  
Author(s):  
J. PESEK ◽  
R. J. BAKER
Keyword(s):  
Triticum Aestivum ◽  
Selection Index ◽  
Triticum Aestivum L ◽  
Hybrid Population ◽  
Index Selection ◽  
Index Method ◽  
Quantitative Characters ◽  
Economic Weights ◽  
Selection For ◽  
Genotypic Effects

Results of a genetic study of four quantitative characters in a cross of two cultivars of Triticum aestivum L. em Thell. indicated that heritability of yield was lower than the heritabilities of maturity and height and that interactions between genotypic effects and year environmental effects were nonsignificant. The modified selection index method, based upon desired genetic gains rather than relative economic weights of traits, is explained in detail and applied to selection for maturity, height and yield from a hybrid population of wheat. The methods and problems of using index selection in self-pollinated species are discussed.

Index selection for both current and future generation gains

1978 ◽  
Vol 26 (2) ◽  
pp. 111-118 ◽  
Author(s):  
J. W. James
Keyword(s):  
Body Weight ◽  
Selection Index ◽  
Future Generation ◽  
Index Selection ◽  
Economic Returns ◽  
Present Value ◽  
Individual Traits ◽  
Selection Decisions ◽  
Selection For ◽  
Combined Selection

ABSTRACTWhen economic returns from current and future generation gains are comparable in magnitude, selection decisions should take account of both sources of gain. A combined selection index is devised to maximize the present value of discounted returns from all sources. The index depends on genetic and phenotypic variances and covari-ances, population structure, discount rate and the relation of annual returns to individual traits. The combined index can be regarded as the sum of separate indices maximizing returns from each source. The method is illustrated with a simple example using wool weight and body weight in sheep.

Sign in / Sign up

Export Citation Format

Share Document