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1.
Gowane Gopal R. Chopra Ashish Prakash Ved Arora A. L. 《Tropical animal health and production》2011,43(1):189-198
Data were collected over a period of 21 years (1988–2008) to estimate (co)variance components for birth weight (BWT), weaning
weight (WWT), 6-month weight (6WT), 9-month weight (9WT), 12-month weight (12WT), average daily gain from birth to weaning
(ADG1), weaning to 6WT (ADG2), and from 6WT to 12WT (ADG3) in Sirohi goats maintained at the Central Sheep and Wool Research
Institute, Avikanagar, Rajasthan, India. Analyses were carried out by restricted maximum likelihood, fitting six animal models
with various combinations of direct and maternal effects. The best model was chosen after testing the improvement of the log-likelihood
values. Heritability estimates for BWT, WWT, 6WT, 9WT, 12WT, ADG1, ADG2, and ADG3 were 0.39 ± 0.05, 0.09 ± 0.03, 0.06 ± 0.02,
0.09 ± 0.03, 0.11 ± 0.03, 0.10 ± 0.3, 0.04 ± 0.02, and 0.01 ± 0.01, respectively. For BWT and ADG1, only direct effects were
significant. Estimate of maternal permanent environmental effect were important for body weights from weaning to 12WT and
also for ADG2 and ADG3. However, direct maternal effects were not significant throughout. Estimate of c
2 were 0.06 ± 0.02, 0.03 ± 0.02, 0.06 ± 0.02, 0.05 ± 0.02, 0.02 ± 0.02, and 0.02 ± 0.02 for 3WT, 6WT, 9WT, 12WT, ADG2, and
ADG3, respectively. The estimated repeatabilities across years of ewe effects on kid body weights were 0.10, 0.08, 0.05, 0.08,
and 0.08 at birth, weaning, 6, 9, and 12 months of age, respectively. Results suggest possibility of modest rate of genetic
progress for body weight traits and ADG1 through selection, whereas only slow progress will be possible for post-weaning gain.
Genetic and phenotypic correlations between body weight traits were high and positive. High genetic correlation between 6WT
and 9WT suggests that selection of animals at 6 months can be carried out instead of present practice of selection at 9 months. 相似文献
2.
Ankit Magotra Yogesh C. Bangar Ashish Chauhan B.S. Malik Z.S. Malik 《Reproduction in domestic animals》2021,56(7):983-991
The purpose of the present study was to obtain estimates of variance components and genetic parameters for direct and maternal effects on various growth traits in Beetal goat by fitting four animal models, attempting to separate direct genetic, maternal genetic and maternal permanent environmental effects under restricted maximum likelihood procedure. The data of 3,308 growth trait records of Beetal kids born during the period from 2004 to 2019 were used in the present study. Based on best fitted models, the direct additive h2 estimates were 0.06, 0.27, 0.37, 0.17 and 0.10 for birth weight (BWT), weight at 3 (WT3), 6 (WT6), 9 (WT9) and 12 (WT12) months of age, respectively. Maternal permanent environmental effects significantly contributed for 10% and 7% of total variance for BWT and WWT, respectively, which reduced direct heritability by 40 and 10% for respective traits from the models without these effects. For average daily gain (ADG1) and Kleiber ratios (KR1) up to weaning period (3 months) traits, maternal permanent environmental effects accounted for 7% and 8% of phenotypic variance, respectively, and resulted in a reduction of 6.6% and 5.4% in direct h2 of respective traits. For post-weaning traits, the maternal effects were non-significant (p > .05) which indicates diminishing influence of mothering ability for these traits. High and positive genetic correlations were obtained among WT3-WT6, WT6-WT9 and WT9-WT12 with correlations of 0.96 ± 0.25, 0.84 ± 0.23 and 0.90 ± 0.13, respectively. Thus, early selection at weaning age can be practised taking into consideration maternal variation for effective response to selection in Beetal goat. 相似文献
3.
Barazandeh A Moghbeli SM Vatankhah M Mohammadabadi M 《Tropical animal health and production》2012,44(4):811-817
Data and pedigree information used in the present study were 3,022 records of kids obtained from the breeding station of Raini
goat. The studied traits were birth weight (BW), weaning weight (WW), average daily gain from birth to weaning (ADG) and Kleiber
ratio at weaning (KR). The model included the fixed effects of sex of kid, type of birth, age of dam, year of birth, month
of birth, and age of kid (days) as covariate that had significant effects, and random effects direct additive genetic, maternal
additive genetic, maternal permanent environmental effects and residual. (Co) variance components were estimated using univariate
and multivariate analysis by WOMBAT software applying four animal models including and ignoring maternal effects. Likelihood
ratio test used to determine the most appropriate models. Heritability
( \texth\texta2 ) \left( {{\text{h}}_{\text{a}}^2} \right) estimates for BW, WW, ADG, and KR according to suitable model were 0.12 ± 0.05, 0.08 ± 0.06, 0.10 ± 0.06, and 0.06 ± 0.05,
respectively. Estimates of the proportion of maternal permanent environmental effect to phenotypic variance (c
2) were 0.17 ± 0.03, 0.07 ± 0.03, and 0.07 ± 0.03 for BW, WW, and ADG, respectively. Genetic correlations among traits were
positive and ranged from 0.53 (BW-ADG) to 1.00 (WW-ADG, WW-KR, and ADG-KR). The maternal permanent environmental correlations
between BW-WW, BW-ADG, and WW-ADG were 0.54, 0.48, and 0.99, respectively. Results indicated that maternal effects, especially
maternal permanent environmental effects are an important source of variation in pre-weaning growth trait and ignoring those
in the model redound incorrect genetic evaluation of kids. 相似文献
4.
The study was conducted to evaluate reproductive performances and estimate genetic parameters for reproduction traits in Arsi-Bale
goats. A total of 792 kidding records collected from 2001 to 2007 were used. Parity of dam, year, season and type of kidding
were investigated as fixed effects by PROC GLM of SAS. Derivative-Free Restricted Maximum Likelihood (DFREML) method was used
to estimate genetic parameters by fitting four animal models. Parity of dam and year of kidding influenced (P < 0.05) all the traits. The overall means for age at first kidding (AFK), kidding interval (KI), litter size at birth (LSB),
litter size at weaning (LSW), litter weight at birth (LWB), litter weight at weaning (LWW), abortion and dystocia were 574.9 ± 8.3 days,
280.0 ± 13.7 days, 1.6 ± 0.03, 1.37 ± 0.03, 3.7 ± 0.08 kg, 9.11 ± 0.38 kg, 3.8% and 0.13%, respectively. The estimates of
direct additive heritability for the traits, except for abortion and dystocia, under the best model (direct animal for AFK
and repeatability model for other traits) were 0.245 ± 0.19, 0.060 ± 0.08, 0.074 ± 0.05, 0.006 ± 0.05, 0.125 ± 0.05, 0.053 ± 0.07,
respectively, while the corresponding permanent environmental effects were 0.00 ± 0.00, 0.07 ± 0.07, 0.08 ± 0.05, 0.172 ± 0.06,
0.03 ± 0.04 and 0.07 ± 0.05, respectively. Repeatability estimates for KI, LSB, LSW, LWB and LWW were 0.13, 0.15, 0.18, 0.16
and 0.12, respectively. Genetic correlations between reproductive traits vary from medium to high. Arsi-Bale goats have good
reproductive performance with low incidence of reproductive disorder. Except for AFK, other traits have low estimates of heritabilities
with high genetic correlation among the traits. Repeated measures of the traits are needed before deciding to keep or cull
the animal. 相似文献
5.
Gowane GR Chopra A Prince LL Mishra AK Arora AL 《Tropical animal health and production》2011,43(2):299-303
The FecB gene of Garole sheep was introgressed into non-prolific Malpura sheep to evolve a new prolific sheep strain Garole × Malpura
(GM), suitable for semi-arid conditions. The present study was conducted to evaluate the impact of breeding program on production
profile of GM sheep and to estimate the genetic parameters for growth traits of GM sheep. Overall prolificacy increased significantly
in the new strain as compared to the native Malpura sheep. In the GM flock of F2 and F2 onwards generation 35.31% single,
55.83% twins, 8.16% triplet and 0.70% quadruplets were obtained during lambing. Over the years, prolificacy in the flock has
increased significantly. Over all least squares means for birth weight, 3, 6, 9, 12 month weight, pre-weaning gain (ADG1)
and post-weaning gain (ADG2) were 1.82 ± 0.03, 9.44 ± 0.18, 14.00 ± 0.24, 16.56 ± 0.33, and 19.32 ± 0.35 kg, and 84.08 ± 1.84
and 35.19 ± 0.99 g, respectively. Majority of the fixed effects had significant influence on the performance traits. The heritability
estimates for birth, 3, 6, 9, 12 month weight, ADG1 and ADG2 were 0.30 ± 0.11, 0.22 ± 0.09, 0.23 ± 0.10, 0.27 ± 0.10, 0.30 ± 0.11,
0.17 ± 0.08, and 0.17 ± 0.10, respectively. Modest rate of genetic progress seems possible for these traits under selection.
The genetic and phenotypic correlations among different body weights were moderate to high and positive. The genetic correlation
of pre and post-weaning daily gains with body weight traits were also high and positive. 相似文献
6.
Sahin A Ulutas Z Yilmaz Adkinson A Adkinson RW 《Tropical animal health and production》2012,44(5):1027-1034
A study was conducted to assess the influence of genetic and environmental factors on Brown Swiss calf birth weight, and to
estimate variance components, genetic parameters, and breeding values. Data were collected on 1,761 Brown Swiss calves born
from 1990 to 2005 in the Konuklar State Farm in Turkey. Mean birth weight for all calves was 39.3 ± 0.09 kg. Least squares
mean birth weights for male and female Brown Swiss calves were 40.3 ± 0.02 and 39.0 ± 0.02 kg, respectively. Variance components,
genetic parameters, and breeding values for birth weight in Brown Swiss calves were estimated by restricted error maximum
likelihood (REML)–best linear unbiased prediction(BLUP) procedures using an MTDFREML (multiple trait derivative free restricted
maximum likelihood) program employing an animal model. Direct heritability (h
d2), maternal heritability (h
m2), total heritability (h
T2), r
am and c
am estimates were 0.12, 0.09, 0.23, −0.58, and −0.06, respectively. The estimated maternal permanent environmental variance
expressed as a proportion of the phenotypic variance (c
2) was 0.05. Breeding values were estimated for the trait and used to evaluate genetic trends across the time period investigated.
The genetic trend linear regression was not different from zero. No genetic trend for birth weight was expected, since there
had been no direct selection pressure on the trait. Absence of a trend confirms that there was no change due to selection
pressure on correlated traits. Genetic and environmental parameter estimates were similar to literature values indicating
that effective selection methods used in more developed improvement programs would be effective in Turkey as well. 相似文献
7.
M. L. Mashiloane K. A. Nephawe A. Maiwashe D. Norris J. W. Ngambi 《Tropical animal health and production》2009,41(8):1723-1730
Data on South African Angus cattle consisting of 45 259 records on weaning weight (WWT), 4 360 records on average daily gain
from on-farm test (ADG-D) and 1 118 from centralized test (ADG-C) were analyzed to evaluate the effect of pre-weaning selection
on estimates of genetic parameters and subsequent estimated breeding values (EBV) for post-weaning average daily gain. (Co)variance
components and genetic parameters for weaning weight (WWT), ADG-C and ADG-D were estimated by REML procedures fitting three
different animal models. Model 1 was a univariate model of WWT, ADG-C or ADG-D and did not account for the effect of pre-weaning
selection on post-weaning ADG. Model 2 was a two-trait model of WWT and either ADG-C or ADG-D. Model 3 was a multi-trait animal
model including WWT, ADG-C and ADG-D. Estimates of heritability for ADG-C were 0.39 ± 0.080, 0.42 ± 0.060 and 0.44 ± 0.010
from Model 1, 2 and 3 respectively. Corresponding estimates for ADG-D were 0.18 ± 0.020, 0.19 ± 0.020 and 0.21 ± 0.020 respectively.
Rank correlations based on EBVs for ADG-C for all bulls were 0.92, 0.83 and 0.94 for Model 1 vs. Model 2, Model 1 vs. Model
3, and Model 2 vs. Model 3, respectively and they indicated a possible re-ranking of bulls when including or excluding a correlated
pre-weaning trait. Rank correlations for ADG-D also followed a similar trend. Inclusion of pre-weaning information in genetic
analysis for post-weaning average daily gain is necessary to account for selection at weaning. 相似文献
8.
Genetic parameters for direct and maternal effects on post-weaning body measurements of Muzaffarnagari sheep in India 总被引:1,自引:1,他引:0
Variance components and genetic parameters were estimated for post-weaning (i.e., at 6, 9, and 12 months of age) body measurements
in Muzaffarnagari sheep maintained at the Central Institute for Research on Goats, Makhdoom, Mathura, India over a period
of 29 years (1976 through 2004). Records of 2,965 lambs descended from 162 rams and 1,213 ewes were used in the study. Analyses
were carried out by REML fitting an animal model and ignoring or including maternal genetic or permanent environmental effects.
Six different animal models were fitted for all traits. The best model was chosen after testing the improvement of the log-likelihood
values. Direct heritability estimates were inflated substantially for all traits when maternal effects were ignored. Moderate
estimates of direct heritability for body length (0.11–0.15), height at withers (0.14–0.19), and heart girth (0.14–0.24) of
lambs were observed at post-weaning stages of growth. Results suggest that only direct additive genetic effects were important
for body measurements at post-weaning stages of growth, and hence, modest rates of genetic progress were possible for post-weaning
body measurements. 相似文献
9.
Genetic parameter estimates for growth traits in Horro sheep 总被引:5,自引:0,他引:5
S. ABEGAZ E. NEGUSSIE G. DUGUMA & J. E. O. REGE 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2002,119(1):35-45
Variance components and genetic parameters were estimated for growth traits: birth weight (BWT), weaning weight (WWT), 6‐month weight (6MWT) and yearling weight (YWT) in indigenous Ethiopian Horro sheep using the average information REML (AIREML). Four different models: sire model (model 1), direct animal model (model 2), direct and maternal animal model (model 3) and direct–maternal animal model including the covariance between direct and maternal effects (model 4) were used. Bivariate analysis by model 2 was also used to estimate genetic correlation between traits. Estimates of direct heritability obtained from models 1–4, respectively, were for BWT 0.25, 0.27, 0.18 and 0.32; for WWT, 0.16, 0.26, 0.1 and 0.14; for 6MWT 0.18, 0.26, 0.16 and 0.16; and for YWT 0.30, 0.28, 0.23, and 0.31. Maternal heritability estimates of 0.12 and 0.23 for BWT; 0.19 and 0.24 for WWT; 0.09 and 0.09 for 6MWT and 0.08 and 0.14 for YWT were obtained from models 3 and 4, respectively. The correlations between direct and maternal additive genetic effects for BWT, WWT, 6MWT and YWT were –0.64, –0.42, 0.002 and –0.46, respectively. On the other hand, the genetic correlations between BWT and the rest of growth traits (WWT, 6MWT and YWT, respectively) were 0.45, 0.33 and 0.31, whereas correlations between WWT and 6MWT, WWT and YWT and 6MWT and YWT were 0.98, 0.84 and 0.87, respectively. The medium to high direct and maternal heritability estimates obtained for BWT and YWT indicate that in Horro sheep faster genetic improvement through selection is possible for these traits and it should consider both (direct and maternal) h2 estimates. However, since the direct‐maternal genetic covariances were found to be negative, caution should be made in making selection decisions. The high genetic correlation among early growth traits imply that genetic improvement in any one of the traits could be made through indirect selection for correlated traits. 相似文献
10.
《Livestock Science》2006,99(1):79-89
Genetic parameters and (co)variance components were estimated for weight at birth and at 15, 30, 45, 60 and 75 days of age for a flock of Muzaffarnagari sheep maintained at the Central Institute for Research on Goats, Makhdoom, Mathura over a period of 27 years (1976–2002). Records on 5201 lambs descended from 1568 ewes and 170 rams were included in the analysis. Analyses were carried out by REML fitting an animal model and ignoring or including maternal genetic or permanent environmental effects. Six different animal models were fitted for all traits, and the best model was chosen after testing improvements in log-likelihood values. Direct heritability estimates were inflated substantially for all traits when maternal effects were ignored. Direct heritability estimates were 0.08 ± 0.02 for birth weight and 0.02 ± 0.02, 0.02 ± 0.02, 0.27 ± 0.08, 0.09 ± 0.04, and 0.29 ± 0.08 for weights at 15, 30, 45, 60, and 75 days, respectively. Maternal genetic effects contributed only 4 to 8% of the total phenotypic variance from birth to 30 days of age, and this effect diminished further with increasing age. Maternal heritability was low for pre-weaning growth traits and should have only a small effect on selection response. Estimates of the fraction of variance due to maternal permanent environmental effects were 0.09 ± 0.02, 0.15 ± 0.04, 0.12 ± 0.03, 0.11 ± 0.04, 0.14 ± 0.02, and 0.08 ± 0.04 for body weights at birth and at 15, 30, 45, 60, and 75 days, respectively. These results indicate that selecting for improved maternal and/or direct effects in Muzaffarnagari sheep would generate only slow genetic progress in early growth traits. 相似文献
11.
Prince Leslie Leo L. Gowane G. R. Swarnkar C. P. Singh D. Arora A. L. 《Tropical animal health and production》2010,42(4):785-791
Genetic parameters for faecal egg count were estimated in naturally challenged Avikalin sheep developed and maintained at
Central Sheep & Wool Research Institute, Avikanagar, India, over a period of 4 years (2004–2007). The data on faecal egg count
for 433 animals descended from 41 sires, and 151 dams were used for the study. Genetic analyses were carried out using restricted
maximum likelihood, fitting an animal model and ignoring or including maternal genetic or permanent environmental effects.
Direct heritability for the trait was 0.149 ± 0.096 when maternal effects were ignored. In the model which takes in to account
direct genetic, maternal genetic and maternal permanent environment effect together, it was observed that maternal heritability
(m2) accounts for 0.6% of total variation whereas maternal permanent environmental effect (c2) accounts for 6.14% of total phenotypic variation. Effect of faecal egg count on the growth characteristics was observed
to be significant. It was seen that wherever FEC was high, body weight or average daily gain declined in active infective
stage. After termination of the infection, these effects were found to be non-significant. Result suggests that direct genetic
and maternal permanent environmental effects were important for this trait; thus, they need to be considered for improvement
in the trait. 相似文献
12.
Direct and maternal (co)variance components and genetic parameters for growth and reproductive traits in the Boran cattle in Kenya 总被引:2,自引:2,他引:0
Direct and maternal (co)variance components and genetic parameters were estimated for growth and reproductive traits in the
Kenya Boran cattle fitting univariate animal models. Data consisted of records on 4502 animals from 81 sires and 1010 dams
collected between 1989 and 2004. The average number of progeny per sire was 56. Direct heritability estimates for growth traits
were 0.34, 0.12, 0.19, 0.08 and 0.14 for birth weight (BW), weaning weight (WW), 12-month weight (12W), 18-month weight (18W)
and 24-month weight (24W), respectively. Maternal heritability increased from 0.14 at weaning to 0.34 at 12 months of age
but reduced to 0.11 at 24 months of age. The maternal permanent environmental effect contributed 16%, 4% and 10% of the total
phenotypic variance for WW, 12W and 18W, respectively. Direct-maternal genetic correlations were negative ranging from −0.14
to −0.58. The heritability estimates for reproductive traits were 0.04, 0.00, 0.15, 0.00 and 0.00 for age at first calving
(AFC), calving interval in the first, second, and third parity, and pooled calving interval. Selection for growth traits should
be practiced with caution since this may lead to a reduction in reproduction efficiency, and direct selection for reproductive
traits may be hampered by their low heritability. 相似文献
13.
Segura-Correa JC Chin-Colli RC Magaña-Monforte JG Núñez-Domínguez R 《Tropical animal health and production》2012,44(2):337-341
Heritabilities and genetic correlations between birth weight (n = 13,741), adjusted 240-day weaning weight (WW, n = 8,806) and age at first calving (AFC, n = 3,955) of Brown Swiss cattle in Mexico were estimated. Data from 91 herds located in 19 of 32 states of Mexico from 1982
to 2006 were provided by the Mexican Brown cattle Breeder Association. Components of (co)variance, direct and maternal heritabilities
were estimated for birth weight, WW and AFC using bivariate animal models. Direct and maternal heritabilities were 0.21 and
0.05 for birth weight, 0.40 and 0.05 for WW, whereas direct heritability for AFC was 0.08. The correlations between direct
and maternal effects for birth weight and WW were −0.49 and −0.64, respectively. The genetic correlations between birth weight–WW
and WW–AFC were 0.36 and −0.02, respectively. Under the conditions of this study, selection for increasing birth weight would
increase WW, but increasing WW will not change AFC. 相似文献
14.
Ghafouri-Kesbi F Abbasi MA Afraz F Babaei M Baneh H Abdollahi Arpanahi R 《Tropical animal health and production》2011,43(6):1153-1159
Genetic parameters for average daily gain from birth to weaning (ADGa), birth to 6 months (ADGb), weaning to 6 months (ADGc),
weaning to yearling age (ADGd), and corresponding Kleiber ratios (KRa, KRb, KRc, and KRd) were estimated by using records
of 3,533 Zandi lambs, descendent of 163 sires and 1265 dams, born between 1991 and 2005 at the Zandi Sheep Breeding Station
at Khojir National Park, Tehran, Iran. A derivative-free algorithm combined with a series of six single-trait linear animal
models was used to estimate phenotypic variance and its direct, maternal, and residual components. In addition, bivariate
analyses were done to estimate (co)variance components between traits. Estimates of direct heritability (h
2
) were 0.11, 0.15, 0.09, 0.10, 0.10, 0.10, 0.06, and 0.07 for ADGa, ADGb, ADGc, ADGd, KRa, KRb, KRc, and KRd, respectively,
thereby indicating the presence of low additive genetic variation for growth rate and Kleiber ratio in this population of
Zandi sheep. Maternal genetic component was found to be significant on ADGa and KRa and contributed 3% and 5%, respectively,
in total phenotypic variance of ADGa and KRa. A widespread range of genetic correlations among traits studied was observed.
Except for negative genetic correlations between ADGa and KRc, ADGa and KRd, and between KRa and KRc, in other cases, genetic
correlations were positive and moderate to very high. Phenotypic correlations ranged from −0.49 (ADGa/KRd) to 0.94 (ADGc/KRc).
These results indicate that selecting for improved growth rate or Kleiber ratio in Zandi sheep would generate a relatively
slow genetic progress. 相似文献
15.
Hossein Mohammadi Mohammad Moradi Shahrebabak Mahmood Vatankhah Hossein Moradi Shahrebabak 《Tropical animal health and production》2012,45(1):185-191
Genetic parameters and genetic trends for birth weight (BW), weaning weight (WW), 6-month weight (6MW), and yearling weight (YW) traits were estimated by using records of 5,634 Makooei lambs, descendants of 289 sires and 1,726 dams, born between 1996 and 2009 at the Makooei sheep breeding station, West Azerbaijan, Iran. The (co)variance components were estimated with different animal models using a restricted maximum likelihood procedure and the most appropriate model for each trait was determined by Akaike’s Information Criterion. Breeding values of animals were predicted with best linear unbiased prediction methodology under multi-trait animal models and genetic trends were estimated by regression mean breeding values on birth year. The most appropriate model for BW was a model including direct and maternal genetic effects, regardless of their covariance. The model for WW and 6MW included direct additive genetic effects. The model for YW included direct genetic effects only. Direct heritabilities based on the best model were estimated 0.15?±?0.04, 0.16?±?0.03, 0.21?±?0.04, and 0.22?±?0.06 for BW, WW, 6MW, and YW, respectively, and maternal heritability obtained 0.08?±?0.02 for BW. Genetic correlations among the traits were positive and varied from 0.28 for BW–YW to 0.66 for BW–WW and phenotypic correlations were generally lower than the genetic correlations. Genetic trends were 8.1?±?2, 67.4?±?5, 38.7?±?4, and 47.6?±?6 g per year for BW, WW, 6MW, and YW, respectively. 相似文献
16.
Genetic and phenotypic parameter estimates for body weights and egg production in Horro chicken of Ethiopia 总被引:1,自引:0,他引:1
Nigussie Dana E. H. vander Waaij Johan A. M. van Arendonk 《Tropical animal health and production》2011,43(1):21-28
A breeding program has been established in 2008 to improve productivity of Horro chicken, an indigenous population in the
western highlands of Ethiopia. The pedigree descended from 26 sires and 260 dams. Body weights were measured every 2 weeks
from hatch to 8 weeks then every 4 weeks for the next 8 weeks. Egg production was recorded to 44 weeks of age for one generation.
Genetic parameters were estimated using animal model fitted with common environmental effects for growth traits and ignoring
common environment for egg production traits. Direct heritabilities ranged from low (0.15 ± 0.08), for body weight at 6 weeks,
to moderate (0.40 ± 0.23), for hatch weight. Heritabilities of common environmental effects on growth were high at hatch (0.39 ± 0.10)
and remained low afterwards. Age at first egg showed a very low heritability (0.06 ± 0.15). Heritabilities of egg numbers
in the first, second, third, and fourth months of laying were 0.32 (±0.13), 0.20 (±0.16), 0.56 (±0.15), and 0.25 (±0.14),
respectively. Heritabilities of cumulative of monthly records of egg numbers were from 0.24 ± 0.16 (for the first 2 months,
EP12) to 0.35 ± 0.16 (over the 6 months, EP16). Body weight at 16 weeks of age (BW16) has a strong genetic correlation with
the cumulative of monthly records: 0.92 (with EP12), 0.69 (with EP36), and 0.73 (with EP16). Besides their strong association,
BW16 and EP16 showed higher heritability, relative to their respective trait categories. These two traits seemed to have common
genes and utilizing them as selection traits would be expected to improve both egg production and growth performance of local
chicken. However, the standard errors of estimates in this study were mostly high indicating that the estimates have low precision.
Parameter estimations based on more data are needed before applying the current results in breeding programs. 相似文献
17.
Juan Carlos Martínez-González Francisco Javier García-Esquivel Gaspar Manuel Parra-Bracamonte Héctor Castillo-Juárez Eugenia Guadalupe Cienfuegos-Rivas 《Tropical animal health and production》2010,42(5):887-892
The aim of this study was to estimate genetic parameters for growth traits in Mexican Nellore cattle. A univariate animal
model was used to estimate (co)variance components and genetic parameters. The traits evaluated were birth weight (BW), weaning
weight (WW), and yearling weight (YW). Models used included the fixed effects of contemporary groups (herd, sex, year, and
season of birth) and age of dam (linear and quadratic) as a covariate. They also included the animal, dam, and residual as
random effects. Phenotypic means (SD) for BW, WW, and YW were 31.4 (1.6), 175 (32), and 333 (70) kg, respectively. Direct
heritability, maternal heritability, and the genetic correlation between additive direct and maternal effects were 0.59, 0.17,
and −0.90 for BW; 0.29, 0.17, and −0.90 for WW; and 0.24, 0.15, and −0.86 for YW, respectively. The results showed moderate
direct and maternal heritabilities for the studied traits. The genetic correlations between direct and maternal effects were
negative and high for all the traits indicating important tradeoffs between direct and maternal effects. There are significant
possibilities for genetic progress for the growth traits studied if they are included in a breeding program considering these
associations. 相似文献
18.
Direct and maternal (co)variance components,genetic parameters and annual trends for growth traits of Dorper sheep in semi-arid Kenya 总被引:2,自引:2,他引:0
Kariuki C. M. Ilatsia Evans D. Kosgey Isaac S. Kahi Alexander K. 《Tropical animal health and production》2010,42(3):473-481
Genetic and phenotypic parameters were estimated for lamb growth traits for the Dorper sheep in semi-arid Kenya using an animal
model. Data on lamb growth performance were extracted from available performance records at the Sheep and Goats Station in
Naivasha, Kenya. Growth traits considered were body weights at birth (BW0, kg), at 1 month (BW1, kg), at 2 months (BW2, kg),
at weaning (WW, kg), at 6 months (BW6, kg), at 9 months (BW9, kg) and at yearling (YW, kg), average daily gain from birth
to 6 months (ADG0–6, gm) and from 6 months to 1 year (ADG6–12, gm). Direct heritability estimates were, correspondingly, 0.18, 0.36, 0.32, 0.28, 0.21, 0.14, 0.29, 0.12 and 0.30 for BW0,
BW1, BW2, WW, BW6, BW9, YW, ADG0–6 and ADG6–12. The corresponding maternal genetic heritability estimates for body weights up to 9 months were 0.16, 0.10, 0.10, 0.19, 0.21
and 0.18. Direct-maternal genetic correlations were negative and high ranging between −0.47 to −0.94. Negative genetic correlations
were observed for ADG0–6–ADG6–12, BW2–ADG6–12, WW–ADG6–12 and BW6–ADG6–12. Phenotypic correlations ranged from 0.15 to 0.96. Maternal effects are important in the growth performance of the Dorper
sheep though a negative correlation exists between direct and maternal genetic effects. The current study has provided important
information on the extent of additive genetic variation in the existing flocks that could now be used in determining the merit
of breeding rams and ewes for sale to the commercial flocks. The estimates provided would form the basis of designing breeding
schemes for the Dorper sheep in Kenya. Implications of the study to future Dorper sheep breeding programmes are also discussed. 相似文献
19.
Growth performance and carcass characteristics of indigenous Mukota pigs of Zimbabwe 总被引:2,自引:2,他引:0
Chimonyo Michael Dzama Kennedy Mapiye Cletos 《Tropical animal health and production》2010,42(5):1001-1007
Carcass quality characteristics are essential in affecting grading and revenue that pig producers realize. No information
is available on the grading of carcasses in indigenous Mukota pigs of Zimbabwe. The objective of this study was to determine
the influence of genotype (Mukota and Large White × Mukota) and sex on post-weaning growth performance and carcass traits
of pigs fed maize cob-based diets. All pigs were weighed at 2-week intervals to estimate average daily gain, dressing percentage
(DP), and carcass lengths. Backfat thickness was also measured. Males had higher body weight gains than females (P < 0.05). Growth rates for Mukota (0.31 ± 0.010) and crossbred (0.41 ± 0.030) pigs were lower in the cool season than the
other seasons (P < 0.05). Body weights were consistently higher in the crossbred than in the Mukota pigs (P < 0.05). Mukota pigs showed a peak growth between 12 and 14 weeks post-weaning (P < 0.05). The DPs were 0.70 and 0.73 for the Mukota and crossbred pigs, respectively (P < 0.05). Crossbred pigs had longer (P < 0.05) carcasses than Mukota (655.5 ± 1.68 versus 507.2 ± 0.92 mm). Although there were no differences in the backfat thickness
between males and females of the crossbred pigs, Mukota males had thicker backfat than the females (P < 0.05). Crossbreeding is, therefore, significant in improving carcass grades of Mukota pigs. 相似文献
20.
Direct and maternal genetic parameters for measures of feed consumption and feed efficiency were estimated using data recorded on 514 performance tested young male Japanese Black cattle during the period from 1978–2004. Measures of feed consumption were daily feed intake, concentrate intake, ratio of roughage intake to feed intake, total digestible nutrient intake, digestible crude protein intake (DCPI) and metabolizable energy intake. Feed efficiency traits included feed conversion ratio (FCR), total digestible nutrient conversion ratio (TCR), digestible crude protein conversion ratio (DCR) and residual feed intake. Data were analyzed using three alternative animal models (including direct and direct plus maternal genetic effects (including or excluding covariance between direct and maternal genetic effects)). The direct heritability estimates for all the measures of feed consumption and feed efficiency were moderate to high, suggesting that sufficient genetic variation exists in these traits which should respond to selection. All the measures of feed consumption were genetically more strongly correlated with residual feed intake than with other measures of feed efficiency. Maternal heritability estimates for DCPI, FCR and TCR were not significantly different from zero, while the corresponding estimates for all the studied traits were low (ranged from 0.07 to 0.24). The estimates of direct heritability for measures of feed consumption were reduced up to 34% when maternal genetic effect was considered in the model. An antagonistic relationship existed between direct and maternal genetic effect (ram) for FCR and DCR, which biased the estimates of direct heritability downwards. The results indicate that maternal effects play an important role in measures of feed consumption and most of the feed efficiency traits, which should be accounted for these traits in genetic evaluation system. 相似文献