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1.
The present study compares embryonic mortality between lines selected for different production traits, assesses the effects of inbreeding of the hen and embryo on embryonic mortality, and estimates genetic parameters of embryonic mortality. The experiment covered 10 generations of selection for increased egg number (EN), egg weight (EW), egg mass (EM) and a control line (C). The data included age at 1st egg, egg number and egg weight. Percent fertile eggs (PF), percent hatched of fertile eggs (PHF) and percent dead chick at hatch (PDH) were also recorded for the selected parents. PDH was higher in the selected lines than in the control line. Among the selected lines, the EW line had the highest embryonic mortality. Inbreeding of the hen and embryo had no significant effect on PDH in any of the lines. Estimates of heritability for PDH were 0.10+/-0.05, 0.02+/-0.02, 0.03+/-0.02 and 0.02+/-0.02 for lines EN, EW, EM and C, respectively. There was a positive genetic correlation between egg weight and PDH in line EW indicating that selection for increased egg weight was associated with high embryonic mortality. A negative genetic correlation between PDH and reproductive traits in line EN was observed, which is favourable.  相似文献   

2.

  1. Genetic parameters were estimated for 5 economically important egg production traits using records collected over 9 years in chickens reared under tropical conditions in Thailand. The data were from two purebred lines and two hybrid lines of layer parent stocks.

  2. The two purebred lines were Rhode Island Red (RIR) and White Plymouth Rock (WPR) and the hybrid lines were formed by crossing a commercial brown egg laying strain to Rhode Island Red (RC) and White Plymouth Rock (WC), respectively.

  3. Five egg production traits were analysed, including age at first egg (AFE), body weight at first egg (BWT), egg weight at first egg (EWFE), number of eggs from the first 17 weeks of lay (EN) and average egg weight over the 17th week of lay (EW).

  4. Fixed effects of year and hatch within year were significant for all 5 traits and were included in the model.

  5. Maternal genetic and permanent environmental effects of the dam were not significant, except for EN and EW in RIR and BWT and EW in WPR.

  6. Estimated heritability of AFE, BWT, EWFE, EN and EW were 0.45, 0.50, 0.29, 0.19 and 0.43 in RIR; 0.44, 0.38, 0.33, 0.20 and 0.38 in WPR; 0.37, 0.41, 0.38, 0.18 and 0.36 in RC; and 0.46, 0.53, 0.36, 0.38 and 0.45 in WC lines, respectively.

  7. The EN was negatively correlated with other traits, except for BWT in RC and AFE and BWT in WC.

  8. It was concluded that selection for increased EN will reduce other egg production traits in purebred and hybrid chicken and therefore EN needs to be combined with other egg production traits in a multi-trait selection index to improve all traits optimally according to a defined breeding objective.

  相似文献   

3.
1. Genetic parameters were estimated in a base population of a closed experimental strain of fowl. Data were obtained on 21 245 Iranian native hens (breeding centre for Fars province) subject to 8 successive generations of selection. This population had been selected for body weight at 12 weeks of age (BW12) and egg number during the first 12 weeks of the laying period (EN), mean egg weight (EW) at weeks 28, 30 and 32, and age at sexual maturity (ASM). 2. The method of multi-traits restricted maximum likelihood with an animal model was used to estimate genetic parameters. Resulting heritabilities for BW12, EN, EW and ASM were 0.68 +/- 0.02, 0.40 +/- 0.02, 0.64 +/- 0.02 and 0.49 +/- 0.02, respectively. 3. Genetic correlations between BW12 and EN, EW and ASM were 0.11 +/- 0.33, 0.54 +/- 0.21 and -0.12 +/- 0.03, respectively. Genetic correlations between EN and EW and ASM were -0.09 +/- 0.03 and -0.85 +/- 0.01, respectively, while between EW and ASM, it was 0.05 +/- 0.03. 4. The overall predicted genetic gains, after 7 generations of selection, estimated by the regression coefficients of the breeding value on generation number were equal to 22.7, 0.17, 0.04 and -1.38, for BW12, EN, EW and ASM, respectively. 5. A pedigree file of 21 245 female and male birds was used to calculate inbreeding coefficients and their influence on production and reproduction traits. Average inbreeding coefficients for all birds, inbred birds, female birds and male birds were 0.048, 0.673, 0.055 and 0.047%, respectively. Regression coefficients of BW12, ASM, EN and EW on inbreeding coefficient for all birds were equal to 0.51 +/- 0.001, 0.31 +/- 0.003, -0.51 +/- 0.003 and 0.03 +/- 0.001, respectively.  相似文献   

4.

Selection is a viable way to increase egg dry matter, an important trait for the egg processing industry, but simultaneously a change in the embryonic environment takes place. The main purpose of this study was to estimate genetic parameters for the percentage of fertile eggs of eggs set (FERT), percentage of eggs hatched of fertile eggs (HATCH), percentage of live chicks 2 weeks post-hatch of hatched eggs (SURV/h) and of fertile eggs (SURV), and their genetic correlations with egg weight, albumen weight, yolk weight, yolk proportion, albumen dry matter and mean chick weight in a White Leghorn selection line. Direct and maternal heritabilities were low for FERT, HATCH and SURV, and non-existent for SURV/h. All direct-direct genetic correlations between reproduction traits and egg composition traits were not significant. Maternal-direct genetic correlations between HATCH and egg weight, albumen weight, yolk weight, yolk proportion and albumen dry matter were - 0.22, - 0.30, 0.28, 0.52 and 0.26, respectively. Similar correlations were found between SURV and egg composition traits. No significant genetic relationship was found between chick weight and post-hatch survival. In conclusion, within the range of values for egg composition in this study, selection for an increased egg dry matter should not impair reproduction.  相似文献   

5.
1. Four Japanese quail lines were developed using 13 generations of reciprocal recurrent (lines AA and BB) or within-line selection (lines DD and EE) for high egg number until 98 d of age. In these lines and their reciprocal crosses, egg production, egg weight and mortality were monitored for up to 21 months to evaluate the impact of selection method and line origin on long-term production and heterosis. 2. Both hen-housed total egg number (EN) and hen-day egg laying rate (ELR) were consistently lower in recurrent lines than in lines under within-line selection: after 13 months of test, the difference was -47.1 eggs for EN and -20% for ELR%, whereas mortality was similar at around 20%. 3. Line EE was the best pure line for early egg production (55.2 eggs at 98 d of age) and also gave eggs which were consistently about 2 g larger than those from line DD but it had the highest overall mortality (78.5%) of all lines. On average, line DD laid 399 eggs (EN) over the whole experiment, 84 more than Line EE. 4. Crossbreds from the 2 types of pure lines and line DD had similar patterns and rates of egg production during the whole experiment, as indicated by the similarity of the curves adjusted for those lines by using the monomolecular model for EN and the modified compartmental model for ELR. 5. However, heterosis was higher from recurrent selection lines and it increased more with time than did heterosis from within-line selection lines.  相似文献   

6.
1. Eggs were stored for two different times at varying temperatures. The effects on hatchability, chick weight at hatch and hatching time were examined in two broiler breeder lines from 33 to 58 weeks of age. 2. Short storage (1 to 3 d). Storage at 20 degrees C compared with 16.5 degrees C reduced hatchability of all eggs set. No effect was observed on hatchability of fertile eggs, hatching time or chick weight. 3. Long storage (9 to 11 d). Storage at 16.5 degrees C compared with 10 degrees C decreased both hatchability of fertile eggs and chick weight at hatch. Incidence of early embryonic death increased and incubation time decreased at 16.5 degrees C compared with 10 degrees C. 4. Chicks from morning eggs were heavier than those from afternoon eggs irrespective of storage conditions. 5. Hatchability (all eggs set and fertile eggs) and chick weight varied with hen age irrespective of storage conditions. During long storage, hatching time varied with hen age independently of breeder line, storage temperature or egg laying time. 6. Hatchability (all eggs set and fertile eggs) was higher in line A than in line B. Line B eggs hatched later and produced heavier chicks than line A eggs irrespective of storage time.  相似文献   

7.
Three strains of commercial leghorns vaccinated at 17 to 22 weeks of age with F strain Mycoplasma gallisepticum (MG) were maintained through 117 weeks of age. The three strains differed in both mortality and percent egg production per hen housed; however, the strains did not differ in egg weight (EW), eggshell strength (ESS), or percent daily egg production. Results of this study indicate EW and ESS for F strain MG-vaccinated hens follow patterns previously reported for uninfected layers. Further, mortality may account, in part, for differences in percent egg production per hen housed between strains of F strain MG-vaccinated hens.  相似文献   

8.
二郎山山地鸡品系间孵化效果的比较分析   总被引：1，自引：0，他引：1  
为指导二郎山山地鸡品种选育,本试验选用SD02、SD03品系第2世代54个家系、2个批次的种蛋进行孵化试验,比较批次间、品系间和品系内家系间的种蛋孵化效果差异。结果显示,SD03的各家系入孵蛋数(47枚)显著高于SD02(40枚)(P<0.05),SD02各家系的健雏率(99.5%)显著高于SD03(98.4%)(P<0.05)。SD03的死精率和死胎率低于SD02,受精率、受精蛋孵化率高于SD02,但差异不显著(P>0.05)。第1批次的受精蛋孵化率和健雏率高于第2批次,死精率和死胎率低于第2批次(P<0.05)。试验表明孵化效果SD03优于SD02,第1批次好于第2批次;SD02品系内家系3、30和48与SD03品系内家系13和49的各孵化指标远低于相应的品系均值,家系选种时应避免选用上述家系种鸡。  相似文献   

9.
1. Inbreeding and heterosis effects for quantitative traits were estimated in two White Leghorn lines selected with reciprocal recurrent selection (RRS) since 1950. 2. Pedigreed progeny were produced from full-sib, half-sib and unrelated pure line as well as reciprocal cross line matings to estimate inbreeding and heterosis effects "within sires". 3. Inbreeding effects estimated as linear regressions agreed well with estimates considering inbreeding as fixed effect. The inbreeding depression per 10% inbreeding was highest for hatchability (6-7%), intermediate for production-related traits (3%), and about 1% for shell quality, body weight and egg weight. 4. Heterosis effects were estimated by comparing pure line and cross line progeny of the same sires. 5. Results indicate considerably less heterosis for egg production than found earlier, which is interpreted as a consequence of pure line selection.  相似文献   

10.
1. Oviposition pattern and egg production traits were recorded in 471 hens from three selection lines. The lines, named according to their selection criteria, were egg number (EN), egg mass (EM) and egg mass, food consumption (EMFC).

2. Mean oviposition intervals within sequences were 24.9, 26.0 and 25.3 h, respectively in the EN, EM and EMFC lines. Corresponding heritability estimates were 0.52, 0.55 and 0.42.

3. The mean oviposition interval within sequences showed a positive genetic correlation with mean oviposition time.

4. Egg weight decreased significantly as the serial number within sequences increased, but only for sequences containing less than 18 eggs.  相似文献   


11.
The influence of the level of magnesium (Mg) in the ration on reproduction by the hen was studied in 2 experiments. In experiment 1, it was found that feeding a semi‐purified ration, containing 56 p.p.m. of Mg, resulted in decreased egg production and reduced serum Mg concentration within 10 to 14 days. Although fertility of eggs was not affected noticeably by Mg deficiency, hatchability of fertile eggs was decreased markedly. The influence of inadequate dietary Mg was partially alleviated by adding 250 p.p.m. Mg to the ration. In experiment 2, a decline in hatchability preceded decreases in egg production and food consumption. A decrease in Mg concentration in egg contents accompanied the decline in hatchability. Hens fed rations containing 50 or 150 p.p.m. added Mg produced eggs of relatively low hatchability by day 14 of the trial. Subsequent to being fed a ration containing 550 p.p.m. added Mg, these hens increased in rate of egg production while hatchability of fertile eggs also increased. The results indicate that the dietary Mg requirement of the laying hen, sufficient to maintain a high rate of production of eggs which hatch satisfactorily, is 400 or more p.p.m.  相似文献   

12.
The Gibbs sampling under a multitrait animal model was applied to detect the single gene affecting chicken performance traits and their pleiotropic actions as well as to estimate the heritability and correlations for these traits. A total of 14 823 individuals of a Rhode Island Red line (RIR) and 18 653 individuals of a Rhode Island White line (RIW) from six generations under long-term selection were recorded. Five performance traits were studied: initial egg production (IEP; until 38th week), egg production (until 54th week), egg weight at 33rd week (EW), age at first egg (AFE), and body weight at 20th week (BW). An analysis was based on the estimated marginal densities of the following parameters: frequencies, additive and dominance effects and variances and covariances (for single gene) as well as additive genetic and residual variances and respective covariances (for polygenes). An inference concerning the mixed inheritance model is performed by visualising the marginal posterior densities of major gene variance separately for all traits. The pleiotropic effect of single locus is expressed as the single gene correlation coefficient. It shows contributions of single genes to BW (10 and 15% of total variance for A22 and K44, respectively) and EW of K44 (9% of total variance). Moreover, a small positive pleiotropic single locus effect in line K44 was also registered. The polygenic heritability estimates obtained were low, except for EW and BW of both lines. Generally, the correlation estimates were in agreement with results reported in literature.  相似文献   

13.
1. A stock of cross-bred CD hens was divided into 'resistant' (R) and 'sensitive' (S) to stress on the basis of the heterophil/lymphocyte (H/L) ratio using the lower 99% confidence limit method for selection. A first generation was produced from these R and S females mated with similarly selected R and S local Barred males. The association between 'resistance' and some production traits was investigated. 2. The proportions of R:S among CD females and Barred males was 51.2:48.8 and 52:48, respectively. Mean H/L ratios for Barred males and females, respectively, were 0.87 +/- 0.03 and 0.83 +/- 0.03 (P > 0.05). 3. Compared with the S group in CD females, the R group had greater egg production (59% vs 51%), egg weight (65.5 g vs 62.6 g) and body weight at 39 weeks (115 g heavier). 4. The superiority of R in terms of proportion of fertile eggs, hatchability and the proportion hatched from those set amounted to 4.8, 6.1 and 5.4%, respectively. 5. The proportion of dead embryos in the R group (5.4%) was lower than in the S group (9.3%). 6. With the F1 generation the R chicks were heavier at hatching. 7. Percentage mortality of male F1 chicks, from hatching to 4 weeks and from 4 to 8 weeks, was lower in the R group. A similar, but non-significant, trend was noted for R females. 8. The progeny of the R group was heavier than the S progeny at 4 and 8 weeks and also the percentage dressed weight of males was greater at 8 weeks. The R group was heavier than the S group at 4, 8 and 12 weeks. 9. These results suggest that selection for general 'resistance', on the basis of the H/L ratio using the 99% lower confidence limit method of selection, is positively correlated with several important production and reproduction traits. Establishing resistant lines with high production rates seems feasible.  相似文献   

14.
1. Hatching time, hatchability of fertile eggs and embryo mortality under standard egg storage (1 or 5 days at 12?±?1°C and 55% relative humidity) and incubation conditions (37·5?±?0·2°C and 50% relative humidity) were analysed in lines long-term selected for high (HG) and low (LG) relative weight gain between 11 and 28?d of age, respectively, and constant body weight at 49?d of age.

2. Egg storage duration did not have an effect on average hatching time. LG quail, characterised by a fast postnatal growth rate immediately after hatching, hatched earlier than HG quail with a low early growth rate (about 391 vs. 406?h after egg setting, respectively).

3. In contrast to hatching time, the hatchability of fertile eggs was influenced by line as well as egg storage duration. Extended storage decreased hatching success in both lines. However, LG eggs exhibited a higher hatchability than HG eggs (1?d storage: 96·0 vs. 82·5%; 5?d storage: 88·7 vs. 72·7%, respectively).

4. Lower hatchability resulted mostly from a higher frequency of embryo death during early (up to d 7) and late (d 14 and later) phases of incubation.

5. An inadequate nutrient supply to embryos in consequence of developmental delay seems to be a key factor decreasing viability of embryos during incubation.  相似文献   

15.
1. Results of an 8-year (1981 to 1988) period of breeding geese for egg production and crammed liver weight, including phenotypic and/or genetic parameters for various traits (1982 to 1985), as well as line tests (1987 to 1988), are summarised for two lines. 2. The regressed annual genetic gains over years were 2.7 eggs and 30.8 g crammed liver. However, there was a decline in the rate of genetic progress after 4 years of selection. 3. Heritability estimates were found to be relatively high for most traits, whereas phenotypic and genetic correlation coefficients between traits were rather low, as would be expected from lines not previously subjected to an intense selection programme. 4. Phenotypic correlation coefficients between part-period records and full-period egg production, suggest that 3-month (October to December) records may be adequate to identify most of the best first-year layers. However, sexual maturity should be treated as a separate trait. 5. The cross between the 'Grey' (male) line, superior in crammed liver weight, and the 'White' (female) line, excelling in egg production, seems to be superior to the pure lines, in a fully-integrated enterprise.  相似文献   

16.
Genetic parameters for mean and for environmental variation in egg weight, body weight, age at first egg, and egg production were estimated in eight layer lines. The data were recorded from years 1999-2007, with on average of 6500 birds per line. An iterative mean-variance REML method was applied with a sire-plus-dam model for mean, a sire model for variance, and a fixed effect of hatch within generation for both mean and variance. The estimated heritability of environmental variation averaged about 5% for body weight, 3% for egg weight, and 11% for age at first egg, but was inconsistent among the lines for egg production (0-15%). Correlations between means and variances were slightly positive for body weight, egg weight, and age at first egg; and strongly negative for egg production. Age at first egg had the highest heritability of environmental variation; and favourable correlations with egg production and with variation in other production traits indicate that reducing variation in this trait may have potential benefits for the breeding industry.  相似文献   

17.
试验以260只如皋黄鸡为素材,采用飞行质谱技术对位于促卵泡素受体(follicle stimulate hormone receptor,FSHR)基因第2内含子的3个SNPs位点进行检测,并对其与繁殖性状的相关性进行了分析。结果表明,C+29329A突变对开产日龄、开产蛋重及40周龄蛋重有显著影响(P<0.05);而C+30582G只与40周龄总产蛋数呈显著相关(P<0.05);G+51411A则对开产日龄、开产体重及40周龄总产蛋数有显著影响(P<0.05)。研究结果显示,FSHR基因有望成为选育高产蛋鸡的分子标记,辅助选育、开发中国地方鸡品种资源。  相似文献   

18.
Although non‐destructive deformation is relevant for assessing eggshell strength, few long‐term selection experiments are documented which use non‐destructive deformation as a selection criterion. This study used restricted maximum likelihood‐based methods with a four‐trait animal model to analyze the effect of non‐destructive deformation on egg production, egg weight and sexual maturity in a two‐way selection experiment involving 17 generations of White Leghorns. In the strong shell line, corresponding to the line selected for low non‐destructive deformation values, the heritability estimates were 0.496 for non‐destructive deformation, 0.253 for egg production, 0.660 for egg weight and 0.446 for sexual maturity. In the weak shell line, corresponding to the line selected for high non‐destructive deformation values, the heritabilities were 0.372, 0.162, 0.703 and 0.404, respectively. An asymmetric response to selection was observed for non‐destructive deformation, egg production and sexual maturity, whereas egg weight decreased for both lines. Using non‐destructive deformation to select for stronger eggshell had a small negative effect on egg production and sexual maturity, suggesting the need for breeding programs to balance selection between eggshell traits and egg production traits. However, the analysis of the genetic correlation between non‐destructive deformation and egg weight revealed that large eggs are not associated with poor eggshell quality.  相似文献   

19.

  • 1.?A study was conducted to study direct dominance genetic and maternal effects on genetic evaluation of production traits in dual-purpose chickens. The data set consisted of records of body weight and egg production of 49 749 Mazandaran fowls from 19 consecutive generations. Based on combinations of different random effects, including direct additive and dominance genetic and maternal additive genetic and environmental effects, 8 different models were compared.

  • 2.?Inclusion of a maternal genetic effect in the models noticeably improved goodness of fit for all traits. Direct dominance genetic effect did not have noticeable effects on goodness of fit but simultaneous inclusion of both direct dominance and maternal additive genetic effects improved fitting criteria and accuracies of genetic parameter estimates for hatching body weight and egg production traits.

  • 3.?Estimates of heritability (h2) for body weights at hatch, 8 weeks and 12 weeks of age (BW0, BW8 and BW12, respectively), age at sexual maturity (ASM), average egg weights at 28–32 weeks of laying period (AEW), egg number (EN) and egg production intensity (EI) were 0.08, 0.21, 0.22, 0.22, 0.21, 0.09 and 0.10, respectively. For BW0, BW8, BW12, ASM, AEW, EN and EI, proportion of dominance genetic to total phenotypic variance (d2) were 0.06, 0.08, 0.01, 0.06, 0.06, 0.08 and 0.07 and maternal heritability estimates (m2) were 0.05, 0.04, 0.03, 0.13, 0.21, 0.07 and 0.03, respectively. Negligible coefficients of maternal environmental effect (c2) from 0.01 to 0.08 were estimated for all traits, other than BW0, which had an estimate of 0.30.

  • 4.?Breeding values (BVs) estimated for body weights at early ages (BW0 and BW8) were considerably affected by components of the models, but almost similar BVs were estimated by different models for higher age body weight (BW12) and egg production traits (ASM, AEW, EN and EI). Generally, it could be concluded that inclusion of maternal effects (both genetic and environmental) and, to a lesser extent, direct dominance genetic effect would improve the accuracy of genetic evaluation for early age body weights in dual-purpose chickens.

  相似文献   

20.
1. Genetic parameters for production and feed efficiency traits in the Orlopp line of turkeys were estimated to determine breeding goals and future potential of the line in a long-term genetic improvement programme.

2. Body weight, egg production and fertility traits were recorded and feed conversion ratio (FCR) was assessed from 16–20 weeks of age.

3. Moderate heritabilities were found for feed intake and body weight gain (0.25 to 0.31). Average FCR was 3.14, with heritability of 0.10. Body weight, breast conformation score and egg production traits showed moderate heritabilities (0.22 to 0.52), while both fertility and hatch of fertile eggs were low (0.04 and 0.09, respectively).

4. Genetic correlations between breast confirmation score, 10- and 18-week body weights were moderate, 0.50 and 0.45, respectively. Average egg weight also showed moderate genetic correlations with 10- and 18-week body weights (0.59 and 0.42).  相似文献   


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