Genetic parameters for direct and maternal effects on body weights of Muzaffarnagari sheep (original) (raw)
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Tropical Animal Health and Production, 2011
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.
Livestock Production Science, 2006
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 . 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 F 0.02 for birth weight and 0.02 F 0.02, 0.02 F 0.02, 0.27 F 0.08, 0.09 F 0.04, and 0.29 F 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 F 0.02, 0.15 F 0.04, 0.12 F 0.03, 0.11 F 0.04, 0.14 F 0.02, and 0.08 F 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. D
Genetic parameters were estimated for weights at birth (BW), 30 days (MW), 120 days weaning weight (WW), and pre-weaning average daily gain (PRADG) of four flocks of Mengali sheep maintained at the Experimental Station CASVAB, Quetta, (ESC), Mastung, Noshki and Quetta over a period of 5 years from 2005 to 2009. Records on 2750 lambs descended from 581 ewes and 56 rams were included in the analysis. Variance components were estimated fitting animal model using restricted maximum likelihood (REML) procedure. Genetic parameters were computed by pos-processing of the variance components. The heritability estimates for BW, MW, WW, and PRADG were 0.39 ± 0.06; 0.125 ± 0.02; 0.177 ± 0.03 and 0.23 ± 0.05, respectively. BW was highly heritable while other growth traits were found moderately heritable, showing larger proportional of environmental variances. In general, heritability estimates were moderate in early growth traits of Mengali sheep. Hence it was suggested that improvement can be achieved by mass selection.
Genetic and phenotypic parameters of body weight in Zandi sheep
The purposes of this study were to estimate genetic parameters for growth traits and to develop a suitable model for the data set used. Data were collected in the Zandi sheep breed from 1992 to 2007 from the Khojir Sheep Breeding Station, Tehran, Iran. Number of observation were 5711 for birth weight (BW), 4619 for weaning weight (WW) , 2801 for body weight at 6-months of age (W6), 2124 for body weight at 9 months of age (W9) and 2113 for yearling weight (W12). (Co) variance components and corresponding genetic parameters were obtained with univariate and multivariate analyses fitting animal models using restricted maximum likelihood (REML) methods that accounted for fixed effects of sex, birth type, age of dam, year of birth and month of birth. Three different animal models were fitted. Based on the most appropriate model fitted, direct heritability, maternal heritability and maternal permanent environmental effect were estimated to range from 0.155 at BW to 0.357 at WW, 0.069 at WW to 0.157 at BW and 0.161 at W9 to 0.171 at W6, respectively. Phenotypic and genetic correlations between all traits were positive, demonstrating the effectiveness of the implemented breeding programs.
NON-GENETIC FACTORS AFFECTING BIRTH AND WEANING WEIGHT IN MANDYA SHEEP
1400 records of Mandya sheep Maintained at Livestock Research and Information Centre (Sheep), KVAFSU, Nagamangala, Mandya (Dst), Karnataka for seven years (2010-2016) were analyzed to estimate the effect of non-genetic factors viz., season of birth, year of birth, sex of lamb and parity of dam on birth and weaning weights. The overall mean of birth weight and weaning weight were 2.07 ? 0.01 kg and 10.13 ? 0.05 kg, respectively. The year of birth of lamb had significant effect on weaning weight and non-significant effect on birth weight. The season of birth of lamb, sex of the lamb and parity of dam were also significantly effects the birth weight and weaning weight of lambs.
Genetic Analysis of Growth Traits in Muzaffarnagari sheep
Tropical Animal Health and Production, 2003
Data on 4112 Muzaffarnagari sheep, maintained at the Central Institute for Research on Goats, Makhdoom, Mathura, India, and recorded between 1976 and 1999, were analysed to study the growth-related traits and their genetic control. The average weights at birth, and at 12 months of age were 3.1±0.2 and 28.0±0.6 kg, respectively. The pre- and post-weaning average daily weight gains were 127.8±3.3 g and 49.4±1.6 g, and the associated growth efficiencies were 3.59±0.08 and 0.95±0.03. Significant differences associated with the year of lambing were observed in body weight, weight gain and efficiency in weight gain at different stages of growth. The lambs born in the dam's second parity were generally of heavier weight and higher daily weight gain than those born in other parities. Males were heavier and had a higher weight gain than females at almost all stages of growth and the differences tended to increase with age. Single-born lambs had a distinct advantage over those born in multiple births at all stages of growth. The heritabilities of all body weights, weight gains and efficiency in weight gains at different stages of growth were moderate (0.18–0.26), except for birth weight, which was of low heritability (0.068±0.01). The phenotypic and genetic correlations among the different body weights were positive and high, except for birth weight. The genetic correlation of the pre- and post-weaning average daily weight gains with body weights were high and positive.
Agricultural and Food Science, 2010
Genetic parameters for birth weight (BW), 3-month weight (3MW), 6-month weight (6MW), 9-month weight (9MW) and yearling weight (YW) in Iranian Moghani sheep were estimated using restricted maximum likelihood procedure of MTDFREML program. The data and pedigree information used in this research were collected at the Breeding station of Moghani sheep (Ardebil province, Iran) during 19872005. Six different animal models were fitted, differentiated by including or excluding maternal effects, with and without covariance between maternal and direct genetic effects. The estimates for direct heritability ranged from 0.31 to 0.54, 0.21 to 0.34, 0.13 to 0.25, 0.11 to 0.22 and 0.10 to 0.17 for BW, 3MW, 6MW, 9MW and YW, respectively. The estimates were substantially higher when maternal effects, either genetic or environmental, were ignored in the model. The results of this study show that full models with maternal genetic and environmental effects gave the most accurate estimates for body wei...
Archives Animal Breeding, 2022
The present study was conducted to estimate the (co)variance components for birth and weaning weight (BW and WW) in 8142 Awassi sheep between 2015 and 2017. Estimates were calculated with single-trait analysis by the average information restricted maximum likelihood (AI-REML) method, using a derivative-free algorithm by fitting six different univariate animal models. The negative of the log-likelihood function (LogL), Akaike information criterion (AIC), and Bayesian information criterion (BIC) tests were used for selecting the best fitted model. In addition, the goodness of fit between the two models was compared with the likelihood ratio test (LRT). Depending on the models, h 2 a and h 2 m ranged from 0.230 to 0.240 and 0.015 to 0.033 for BW, and 0.108 to 0.168 and 0.024 to 0.081 for WW, respectively. Model 3 for BW and Model 2 for WW were chosen as the best models by LogL comparison criteria. According to the LRT ratio test Model 2, Model 3, and Model 4 for BW and Model 2, Model 3, Model 4, Model 5, and Model 6 for WW were significant (p < 0.05). Including maternal genetic or maternal permanent environmental effects in these models was found to be significant in terms of parameter estimates.
Phenotypic Variations in Birth and Body Weight of the Local Sheep at Earlier Age
2018
The aim of this study was to investigate the phenotypic variations in birth and body weights at various ages of local sheep, total of 37 heads, born as singletons n =13, twins n = 19, triplets n =5. The lambs were reared at two locations Purwakarta and Jatinangor under extensive feeding system and grazing. All animals were weighed monthly till six months of age by hang scale (kg). Data analyzed by SAS (version 9.0). Means ± SE for the birth and body weights were performed. Analysis of variance GLM was done to examine the effects of sex, type of birth and location on the measured variables. Results shown that birth weight ranged between 1.50 to 3.50 kg, the overall means of the type of birth are: single, twins and triplets were 2.69±0.12, 2.24±0.11 and 1.96±0.20 respectively, male weight were 2.355±0.122, females were 2.220±0.126, also birth weight at Purwakarta is of 2.218±0.106 and Jatinangor is of 2.447±0.156. Males heavier than females but there are no significant differences amo...