Comparison of statistical models to analyse the genetic effect on within-litter variance in pigs

Wittenburg, Dörte; Guiard, V.; Teuscher, F.; Reinsch, Norbert

doi:10.1017/s1751731108002851

Cited by 14 publications

(21 citation statements)

References 22 publications

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“…06-0 . 11 (Damgaard et al, 2003 ;Wittenburg et al, 2008;Canario et al, 2010). In some older studies, ANOVA techniques were used to analyse within-family variances of dairy bulls with large offspring groups, and substantial differences between sires were found (Van Vleck, 1968 ;Clay et al, 1979).…”

Section: Empirical Evidence For Genetic Variation In Environmental Vamentioning

confidence: 99%

Genetic analysis of environmental variation

2010

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SummaryEnvironmental variation (V E ) in a quantitative trait -variation in phenotype that cannot be explained by genetic variation or identifiable genetic differences -can be regarded as being under some degree of genetic control. Such variation may be either between repeated expressions of the same trait within individuals (e.g. for bilateral traits), in the phenotype of different individuals, where variation within families may differ, or in both components. We consider alternative models for defining the distribution of phenotypes to include a component due to heterogeneity of V E . We review evidence for the presence of genetic variation in V E and estimates of its magnitude. Typically the heritability of V E is under 10 %, but its genetic coefficient of variation is typically 20 % or more. We consider experimental designs appropriate for estimating genetic variance in V E and review alternative methods of estimation. We consider the effects of stabilizing and directional selection on V E and review both the forces that might be maintaining levels of V E and heritability found in populations. We also evaluate the opportunities for reducing V E in breeding programmes. Although empirical and theoretical studies have increased our understanding of genetic control of environmental variance, many issues remain unresolved.

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Section: Empirical Evidence For Genetic Variation In Environmental Vamentioning

confidence: 99%

Genetic analysis of environmental variation

2010

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“…Crown-rump length (the supine length of the piglet from the crown of its head to the base of its tail) was determined within 8 h after birth. Intralitter variability of birth weight was calculated according to Wittenburg et al (2008). Body mass index (kg/m 2 ) and ponderal index (kg/m 3 ) were calculated from birth weight and crown-rump length (Baxter et al, 2008).…”

Section: Animals and Treatmentsmentioning

confidence: 99%

Limited and excess dietary protein during gestation affects growth and compositional traits in gilts and impairs offspring fetal growth1,2

Rehfeldt

Lang

Görs

et al. 2011

Journal of Animal Science

138

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The aim of this study was to investigate whether dietary protein intake during gestation less than or greater than recommendations affects gilts growth and body composition, gestation outcome, and colostrum composition. German Landrace gilts were fed gestation diets (13.7 MJ of ME/kg) containing a low (n = 18; LP, 6.5% CP), an adequate (n = 20; AP, 12.1%), or a high (n = 16; HP, 30%) protein content corresponding to a protein:carbohydrate ratio of 1:10.4, 1:5, and 1:1.3, respectively, from mating until farrowing. Gilts were inseminated by semen of pure German Landrace boars and induced to farrow at 114 d postcoitum (dpc; Exp. 1). Energy and protein intake during gestation were 33.3, 34.4, and 35.8 MJ of ME/d (P < 0.001) and 160, 328, and 768 g/d, respectively, in LP, AP, and HP gilts (P < 0.001). From insemination to 109 dpc, BW gain was least in LP (42.1 kg), intermediate in HP (63.1 kg), and greatest in AP gilts (68.3 kg), whereas increase of backfat thickness was least in gilts fed the HP diet compared with LP and AP diets (3.8, 5.1, 5.0 mm; P = 0.01). Litter size, % stillborn piglets, and mummies were unaffected (P > 0.28) by the gestation diet. Total litter weight tended to be less in the offspring of LP and HP gilts (14.67, 13.77 vs. 15.96 kg; P = 0.07), and the percentage of male piglets was greater in litters of HP gilts (59.4%; P < 0.01). In piglets originating from LP and HP gilts, individual birth weight was less (1.20, 1.21 vs. 1.40 kg; P = 0.001) and birth weight/crown-rump length ratio was reduced (45.3, 46.4 vs. 50.7 g/cm; P = 0.003). Colostrum fat (7.8, 7.4 vs. 8.1%) and lactose concentrations (2.2, 2.1 vs. 2.6%) tended to be reduced in LP and HP gilts (P = 0.10). In Exp. 2, 28 gilts (LP, 10; AP, 9; HP, 9) were treated as in Exp. 1 but slaughtered at 64 dpc. At 64 dpc, LP gilts were 7% lighter than AP gilts (P = 0.03), whereas HP gilts were similar to AP gilts. Body composition was markedly altered in response to LP and HP feeding with less lean (P < 0.01) and greater fat content (P = 0.02 to 0.04) in LP and less fat content (P = 0.02 to 0.04) in HP gilts. Fetal litter weight and number, and embryonic survival at 64 dpc were not affected by the diets. These results indicated that gestation diets containing protein at 50 and 250% of recommendations and differing in protein:carbohydrate ratio led to marked changes in protein and fat metabolism in gilts resulting in fetal growth retardation of 15%, which mainly occurred during the second half of gestation.

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“…In the model used for the genetic analyses, dependence on the proportions of approved dogs per litter and the proportions of males among the approved littermates was accounted for by the respective class variables. Studies on the birth weight of piglets have shown that within-litter variance can be analyzed across sexes and that it is then adequately modeled by weighting for the proportion of males in the litter (Wittenburg et al, 2008). Because conformation data on whole litters was usually not available for the GSD, additional modeling of the amount of available information per litter Table 6.…”

Section: Discussionmentioning

confidence: 99%

Selection for conformation and conformational homogeneity of litters in the German shepherd dog

Stock

Dammann

Distl

2012

Journal of Animal Science

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Breeding standards of most dog breeds specify tolerable ranges of certain conformation traits. In the German shepherd dog (GSD), current means for withers height (WH) and BW are close to the upper breed limits. Therefore, strategies to avoid a further increase in size and to maximize the proportion of dogs fitting the breeding standard with respect to WH and BW should be compared. Body measurements were available for 14,416 male and 21,612 female GSD from 26,155 litters. Withers height and body mass index (BMI; i.e., BW/WH(2)) were considered direct selection traits. Using information on 17,154 GSD from litters with at least 2 dogs with conformation data, we defined within-litter variances of WH (vWH) and BMI (vBMI) as traits to select for the conformational homogeneity of litters. Officially recorded scores for canine hip dysplasia (CHD) of all dogs were used to monitor possible side effects of conformation selection on CHD. Genetic parameters were estimated multivariately in linear animal models by using Gibbs sampling. Heritabilities ranged between 0.19 and 0.34 for all traits, and additive genetic correlations between WH and vWH were -0.11 and those between BMI and vBMI were 0.11. The expected selection response was studied using the relative breeding values (RBV) of parents, assuming exclusion of sires, dams, or both with RBV larger than 120 and comparing means of WH, BMI, and CHD scores between offspring of all and selected parents. Concurrent selection for small WH and vWH was found to reduce the mean WH in males and females most efficiently while having little effect on CHD distributions. Multiple-trait selection for WH, vWH, BMI, and vBMI was hindered by the negative genetic correlations between the traits, and it tended to interfere with improvement of CHD status. Use of the RBV for WH and vWH for conformation selection is therefore recommended to maximize breeding success with regard to conformation and conformational homogeneity in the GSD.

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Comparison of statistical models to analyse the genetic effect on within-litter variance in pigs

Cited by 14 publications

References 22 publications

Genetic analysis of environmental variation

Genetic analysis of environmental variation

Limited and excess dietary protein during gestation affects growth and compositional traits in gilts and impairs offspring fetal growth1,2

Selection for conformation and conformational homogeneity of litters in the German shepherd dog

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