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Selección de modelos, parámetros genéticos y tendencias genéticas en las evaluaciones genéticas nacionales de bovinos Brangus y Salers
Domínguez-Viveros, Joel;Rodríguez-Almeida, Felipe A.;Ortega-Gutiérrez, Juan A.;Flores-Mari？elarena, Alberto;
Agrociencia , 2009,
Abstract: the objectives of the present study were to define statistical models for the national genetic evaluations of salers (sl) and brangus (br) cattle, to estimate genetic parameters, and to predict genetic values (dgv=direct; mgv=maternal) and analyze their trends. the variables studied were the weights at birth (bw; sl=3583, br = 17107) and at weaning adjusted to 205 d (ww; sl=3518, br = 16119), using pedigrees from the mexican associations of sl (n=10531) and br (n=35894) breeders. the definition of the model started with a complete mixed model that included the fixed effect of year-season-sex-herd, plus the covariable age of the cow. as random, the model included the direct and maternal genetic effects, covariance between them and the permanent environment maternal effects. selection of the best model was carried out with likelihood ratio tests, akaike and schwartz information criteria. the results of the selection of model coincide with the three methodologies used. in br, the complete model was selected for bw and ww. in sl, the model selected for bw included the direct and maternal genetic effects, plus the covariance between them; while for ww, the model selected considered the direct and maternal genetic effects, plus the permanent environment maternal effects. the range for direct heritability based on the models selected was 0.13 to 0.20, and for the maternal heritabilities it was 0.4 to 0.8. trends of dgv for bw and mgv for ww were negative in both breeds: -0.01 kg year-1and -0.21 kg year-1 in br; -0.02 kg-1 and -0.03 kg year-1 in sl. for ww in br the dgv presented a positive trend (0.33 kg year-1). it is recommended to select the most adequate models before genetic evaluations. also, a strategic analysis is required for the implications of negative genetic trends observed in mgv for ww.
Estimation of genetic parameters and genetic trends for weight and body measurements at birth in sheep populations in Thailand
China Supakorn,Winai Pralomkarn,Suwit Anothaisinthawee
Songklanakarin Journal of Science and Technology , 2013,
Abstract: The main objective of this study was to estimate the genetic parameters and genetic trends for birth weight (BW),heart girth (HG), and body length (BL) at birth of sheep populations in Thailand. Data were collected during 1998 to 2011 fromfour livestock research and testing stations. Fixed effect testing showed that sex, herd, contemporary group and breed groupgreatly influenced on the investigated traits (P<0.05). The log likelihood ratio test showed that all traits significantly affectedby maternal additive genetic effect as well as covariance between animal effects. Estimated direct heritabilities from multivariate analysis of the model for BW, HG and BL were 0.32, 0.52 and 0.54, while estimated maternal heritabilities were 0.23,0.14 and 0.14, respectively. Positive correlations were found among direct additive genetic (0.29 to 0.97), maternal additivegenetic (0.23 to 0.95), and phenotype (0.18 to 0.96). Direct-maternal correlations within traits (-0.68 for BW, -0.92 for HG and-0.89 for BL) and between traits (-0.89 to -0.08) were antagonistic effect. Direct additive genetic trends for BW, HG and BL inthe second period (2005 to 2011) were significantly increased (0.02 kg/year, 0.89 and 0.73 cm/year) while maternal additivegenetic trends characteristically depicted significantly decreased (-0.01 kg/year, -0.92 and -0.72 cm/year).
Genetic improvement and population structure of the Nelore breed in Northern Brazil
Malhado, Carlos Henrique Mendes;Carneiro, Paulo Luiz Souza;Malhado, Ana Claudia Mendes;Martins Filho, Raimundo;Bozzi, Riccardo;Ladle, Richard James;
Pesquisa Agropecuária Brasileira , 2010, DOI: 10.1590/S0100-204X2010001000009
Abstract: the objective of this work was to evaluate the population structure and the genetic and phenotypic progress of nelore cattle in northern brazil. pedigree information concerning animals born between 1942 and 2006 were analyzed. population structure was performed using the endog program. out of the 140,628 animals studied, 67.7, 14.52 and 3.18% had complete pedigree record of the first, second and third parental generation, respectively. inbreeding and average relatedness coefficients were low: 0.2 and 0.13%, respectively. however, these parameters may have been underestimated, since information on pedigree was incomplete. the effective number of founders was 370 and the genetic contribution of 10, 50 and 448 most influent ancestors explained 13.2, 28 and 50% of the genetic variability in the population, respectively. the genetic variability for growth traits and population structure demonstrates high probability of increasing productivity through selective breeding. moreover, management strategies to reduce the currently observed age at first calving and generation intervals are important for nelore cattle genetic improvement.
Cattle Conservation in the 21st Century: A Mini Review  [PDF]
Umar-Faruq Olayinka Bolaji, Afees Abiola Ajasa, Ridwan Olawale Ahmed, Semiu Folaniyi Bello, Obiajulu Emenike Ositanwosu
Open Journal of Animal Sciences (OJAS) , 2021, DOI: 10.4236/ojas.2021.112023
Abstract: Cattle are arguably the most important livestock species. Since the beginning of this century, the loss of genetic diversity within this species has been a major concern as this could have serious consequences on the ability of this species to respond to future production constraints. Genetic diversity has traditionally been accessed from pedigree, however, with the advances in molecular genetics new opportunities have emerged. We examined different methods for accessing genetic diversity and estimating genetic diversity parameters at the genomic level. We also examined criteria and strategies for the conservation of animal genetic resources. Finally, we examined genomic studies on some endangered cattle breeds.
Genetic variability in ultrasound records of breast muscle in a broiler breeding program  [PDF]
Leila de Genova Gaya
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.58A2001
Abstract:

Breast weight is one of the most economically important traits in the poultry industry, but direct selection for weight is expensive. The use of ultrasonography enables in vivo measurements of the broiler’s breast muscle size, which may be much more feasible for broiler selection. Previous studies of broilers concluded that ultrasound of the breast muscle is feasible and favorable for meat production. According to previously obtained genetic parameters, breast weight could be efficiently improved by ultrasound of the breast muscle. The use of ultrasonography for the indirect selection of breast weight does not affect the body composition or meat quality of broilers, despite the meat’s paleness and shear force; therefore, the use of ultrasound as a selection criterion might be a useful monitoring tool. Studies on the utilization of ultrasound in broiler breeding programs allow a better understanding of the relationship between traits of economic interest and the establishment of the selection schemes.

The Effect of Seed Size on Phytochemical Composition in Cowpea Lines (Vigna unguiculata (L.) Walp.) from Burkina Faso  [PDF]
Pierre Alexandre Eric Djifaby Sombié, Hemayoro Sama, Antoine Barro, Adama Hilou, Martin Kiendrébéogo
Agricultural Sciences (AS) , 2021, DOI: 10.4236/as.2021.1212093
Abstract: The study aimed to determine the effect of seeds size (length, width, thickness and 100 seeds-weight) on their phytochemical composition (total phenolics, total flavonoids, total proteins, soluble sugars and starch) of cowpea accessions (Vigna unguiculata (L.) Walp.) grown in Burkina Faso. The genotypes and their descendants had length, width, thickness and 100 seeds weight between 80 ± 0.7 to 7.40 ± 0.46 cm; 6.51 ± 0.41 to 5.76 ± 0.46 cm; 5.15 ± 0.37 to 4.22 ± 0.22 cm; 12.93 ± 0.09 to 20.16 ± 0.39 g respectively. Total phenol, total flavonoid and starch contents ranged from 585.37 ± 9.73 to 1704.71 ± 4.87 mg GAE per 100 g DW; 41.42 ± 2.03 to 52.26 ± 0.75 mg QE per 100 g DW; 6.45% ± 0.3% to 46.58% ± 0.12% respectively. The soluble sugars and total proteins contents were ranged respectively from 149.33 ± 3.80 to 432.82 ± 40.81 μg/100mg, and 20.28 ± 0.17 to 27.32 ± 0.17 (%). Seeds size characters had significant and positive correlations with starch content, and significant and negative correlations with total phenolic content. The study of the genetic parameters of phytochemical traits also revealed that they are slightly influenced by the environment. Genetic factors are believed to account for the variation in the observed seed traits, which provides a high potential of studied accessions for breeding programs.
Tendências genéticas para características relacionadas à velocidade de crescimento em bovinos Nelore na regi？o nordeste do Brasil
Malhado, Carlos Henrique Mendes;Martins Filho, Raimundo;L？bo, Raimundo Nonato Braga;Facó, Olivardo;Azevedo, Danielle Maria Machado Ribeiro;Souza, Julio César de;Oliveira, Sonia Maria Pinheiro;
Revista Brasileira de Zootecnia , 2005, DOI: 10.1590/S1516-35982005000100008
Abstract: the objectives of this work were to estimate the genetic parameters and the genetic trends of the direct and maternal effects for the trait days to gain 160 kg (d160) in the pre-weaning period, and of the direct effect for the trait days to gain 240 kg (d240) in the post-weaning period, of animals of nellore breed, born from 1965 to 2001 in the northeast region of brazil. the analyses were carried out using the mtdfreml software. for d160 the model included the direct and maternal genetic random effects and maternal permanent environmental effect, besides the fixed effects of contemporary group and the covariate age of dam at calving, assuming the covariance between maternal and direct effect equal to zero (sam=0). for d240, the same fixed effects were considered, however, just the direct genetic effect as random. the genetic trends were estimated by linear regression of the breeding values on year of birth of the animals. the direct and maternal heritabilities for d160, respectively, were 0.12 ± 0.01 and 0.07 ± 0.02. the direct heritability for d240 was 0.16 ± 0.02. the genetic trends of the direct effects were significant, with estimated values of -0.14 and -0.41 days/year for d160 and d240, respectively. the genetic trend of the maternal effect for d160 was significant and equal to -0.0037 days/year. the genetic trends were favorable, however, inferiors the potential gain.
Tendencias Genéticas y Fenotípicas de Características de Crecimiento en el Ganado Brahman de Registro de México.
Parra-Bracamonte,Gaspar Manuel; Martínez-González,Juan Carlos; García-Esquivel,Francisco Javier; González-Reyna,Arnoldo; Briones-Encinia,Florencio; Cienfuegos-Rivas,Eugenia Guadalupe;
Revista Científica , 2007,
Abstract: the objectives of the present study were to calculate phenotypic and genetic trend lines for birth weight (pn), and age corrected weaning weight (p205), yearling (p365) and at 550 days (p550). weights of registered brahman cattle in mexico, years included 1993 to 2003, corresponded to the weights control program of the mexican association of zebu breeders (amcc). the expected breeding values for genetic trends were estimated with the expected progeny differences (epd？s) from a previous study. annual phenotypic trends were significantly (p<0.05), with the phenotypic change estimate for pn, p205, p365 and p550 of 0.142; 2.134; 8.759 and 12.820 kg/year, respectively. annual direct genetic trends were significant (p<0.05) only for p205 and p550. genetic change estimates was: 1 g/year for pn; 191 g/year for p205, 262 g/year for p365, and 608 g/year for p550. genetic maternal trends were only significant (p<0.05) for p365 and p550. the estimates of the annual changes were 2.09-6, -1.0, 13.0 and 36.0 g/year for pn, p205, p365 and p550, respectively. both phenotypic and genetic direct annual trends seem to match with the pcdp implementation, mainly in postweaning traits. the annual change in the evaluated period has been positive but small. the use of breeding strategies based on expected progeny differences would increase significantly the possibility of higher genetic progress but using only phenotypic criteria.
Potencial genético da popula？？o de milho UFV 7 para o melhoramento em Minas Gerais
Faluba, Joyce de Souza;Miranda, Glauco Vieira;DeLima, Rodrigo Oliveira;Souza, Leandro Vagno de;Debem, Enoch Assis;Oliveira, Ana Maria Cruz e;
Ciência Rural , 2010, DOI: 10.1590/S0103-84782010000600002
Abstract: the objective was to assess the genetic potential of maize population ufv 7 for breeding in minas gerais, brazil. three experiments were installed with the maize population ufv 7 in the three regions of minas gerais, in the harvest of 2006/2007. there was genotype x environment interaction for all characters. it was observed genetic variability for grain yield, plant height and ear height in maize population ufv 7, in the three regions. the southeast region was where the maize population ufv 7 had the highest parameters. the population ufv 7 presented high grain yield, 9 112kg ha-1 in the southeast, average grain yield, 6 510kg ha-1 in the west and low, 4 572kg ha-1 in the central region. heritability estimate and cvg / cve for grain yield were higher than 60% and 1.00, respectively. grain yield had significant and positive genetic correlation with plant height and ear height, in western and central, and the prolificacy in central and southeast. for maize population ufv 7 it was conclude that it has potential for extraction of lines in the central region; it has the potential for immediate use in the southeast and for new cycles selection in the western region of minas gerais. the selection for pg provides an indirect increase in plant height and ear height, in the west and central.
Plant selection in F2 segregating populations of papaya from commercial hybrids
Oliveira, Eder Jorge;Fraife Filho, Gilberto de Andrade;Freitas, Juan Paulo Xavier de;Dantas, Jorge Luiz Loyola;Resende, Marcos Deon Vilela de;
Crop Breeding and Applied Biotechnology , 2012, DOI: 10.1590/S1984-70332012000300005
Abstract: the objective of this paper was to estimate the genetic parameters and additive genetic values in segregating populations of papaya using the mixed model methodology. two f2 populations from tainung and calimosa hybrids were evaluated. the experimental design was an augmented block with four replicates, and golden and calimosa cultivars were the common treatment. estimates of individual heritability were high for fruit length (fl) and weight (fw), moderate for fruit diameter (fd), and low for total soluble solids (tss) and fruit firmness (ff). considering ff and tss as main traits for selection, genotypes of calimosa-f2 population showed better performance to ff, but worse concerning tss. it was selected 18.3% and 24.6% of plants from tainung-f2 and calimosa-f2 populations, respectively. negative correlation between tss and ff was not able to reduce the genetic gains. the segregating populations from calimosa hybrid are more promising for the selection of papaya lines.
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