Gaspar Manuel Parra-Bracamonte

Genetic parameters for growth traits in Mexican Nellore cattle

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.

Assessment of genetic structure in Mexican charolais herds using microsatellite markers

Knowledge of livestock genetic diversity is an essential step to respond to commercial demands and reach production objectives in different environments and production systems. The evaluation of animal genetic diversity is achieved by using molecular markers. Microsatellites are the most used markers for studies of this type. Eleven microsatellites were used to evaluate the genetic variation from three populations of Charolais cattle located in northeast Mexico. The studied populations exhibited a high allelic variability with a mean heterozygosity of 0.5. A moderate genetic differentiation between the Charolais populations (F ST = 0.079; P

Genetic diversity and structure among subspecies of white-tailed deer in Mexico

Abstract The white-tailed deer (Odocoileus virginianus) occurs over a broad latitudinal range from South America to Canada. Thirty-eight subspecies are recognized, 14 of which occur in Mexico. Genetic studies in Latin America are lacking and the diversity and structure of white-tailed deer in Mexico are unknown. We sampled white-tailed deer from 13 sites in the range of 5 subspecies occurring in Mexico, O. v. texanus, O. v. carminis, O. v. veraecrucis, O. v. sinaloae, and O. v. yucatanensis. We estimated genetic diversity and structure based on 12 microsatellite DNA loci. Observed heterozygosity (HO) was comparable to that of white-tailed deer in the United States (HO = 0.53–0.64), with the exception of O. v. yucatanensis (HO = 0.41). We observed statistically significant genetic structure among all 13 sites (FST = 0.15). Analysis of molecular variance revealed that grouping sites by subspecies (FSC = 0.09) or geographic region (FSC = 0.13–0.14) explained a moderate portion of genetic variation. However, no higher-level group minimized differentiation among populations within the subspecies or regional groups (FST = 0.16–0.20). Pairwise genetic distances among sites were correlated with geographic distance (r2 = 0.38), but some geographically proximate sites were genetically differentiated (FST > 0.20), especially in the Yucatan. Deer in the Yucatan were genetically differentiated from other subspecies and had comparatively lower genetic diversity, consistent with the biogeographic history of the region. Populations of white-tailed deer in Mexico are subject to a range of management challenges. Additional research is needed to understand the effect of management on the diversity and genetic structure of white-tailed deer. Resumen El venado de cola blanca (Odocoileus virginianus) se distribuye en un amplio rango latitudinal desde el sur de América hasta Canadá. De las 38 subespecies reconocidas, 14 habitan en México. Debido al número limitado de estudios genéticos en Latinoamérica, la diversidad y estructura poblacional del venado de cola blanca en México es desconocida. En este estudio, muestreamos venado de cola blanca de 13 sitios ubicados dentro del rango de distribución de 5 subespecies de México, O. v. texanus, O. v. carminis, O. v. veraecrucis, O. v. sinaloae, and O. v. yucatanensis. La diversidad y estructura genética fue estimada con 12 marcadores microsatélites. La heterocigosidad observada fue comparable a lo observado en el venado de cola blanca de Norteamérica (HO = 0.53–0.64), con excepción de O. v. yucatanensis (HO = 0.41). Se observó una estructura genética significativa entre los 13 sitios de muestreo (FST = 0.15). El análisis de varianza molecular reveló que los sitios de muestreo agrupados por subespecie (FSC = 0.09) o región geográfica (FSC = 0.13–0.14) explicaron una porción moderada de la variación genética. Sin embargo, la diferenciación entre las poblaciones no fue minimizada a un nivel de agrupamiento mayor, es decir dentro de subespecies o grupos regionales (FST = 0.16–0.20). La distancia genética entre sitios de muestreo estuvo correlacionada con la distancia geográfica (r2 = 0.38), pero algunos sitios geográficamente próximos estuvieron genéticamente diferenciados (FST > 0.20), especialmente en Yucatán. El venado de cola blanca de Yucatán fue diferenciado genéticamente de las otras subespecies y fue comparativamente el de menor diversidad genética, lo cual es consistente con la historia biogeográfica de la región. Las poblaciones de venado cola blanca en México están sujetas a diversos retos de manejo. Por lo tanto, se requiere de investigación adicional para comprender el efecto sobre su diversidad y estructura genética.

Genetic diversity of tyrosine hydroxylase (TH) and dopamine b-hydroxylase (DBH) genes in cattle breeds

DNA from four cattle breeds was used to re-sequence all of the exons and 56% of the introns of the bovine tyrosine hydroxylase (TH) gene and 97% and 13% of the bovine dopamine β-hydroxylase (DBH) coding and non-coding sequences, respectively. Two novel single nucleotide polymorphisms (SNPs) and a microsatellite motif were found in the TH sequences. The DBH sequences contained 62 nucleotide changes, including eight non-synonymous SNPs (nsSNPs) that are of particular interest because they may alter protein function and therefore affect the phenotype. These DBH nsSNPs resulted in amino acid substitutions that were predicted to destabilize the protein structure. Six SNPs (one from TH and five from DBH non-synonymous SNPs) were genotyped in 140 animals; all of them were polymorphic and had a minor allele frequency of > 9%. There were significant differences in the intra- and inter-population haplotype distributions. The haplotype differences between Brahman cattle and the three B. t. taurus breeds (Charolais, Holstein and Lidia) were interesting from a behavioural point of view because of the differences in temperament between these breeds.

Comparación de modelos alternativos en la evaluación genética de variables de crecimiento de ganado Brahman de registro en México

Five genetic evaluation models of registered Brahman cattle in Mexico were compared for birth weight (PN), weaning (PD), yearling (PA) and final weight at 55...

Genomewide association analysis of growth traits in Charolais beef cattle1

The objective of this study was to perform a genomewide association study (GWAS) for growth traits in Charolais beef cattle and to identify SNP markers and genes associated with these traits. Our study included 855 animals genotyped using 76,883 SNP from the GeneSeek Genomic Profiler Bovine HD panel. The examined phenotypic data included birth, weaning, and yearling weights as well as pre- and postweaning ADG. After quality control, 68,337 SNP and 823 animals were retained in the analysis. The association analysis was performed using the principal components method via the egscore function of the GenABEL version 1.8-0 package in the R environment. Eighteen SNP located in 13 BTA were associated with growth traits ( < 5 × 10). The most important genes in these genomic regions were (), (), (), (), and ( [angiotensinase C]), due to their relationships with perinatal and postnatal survival, bone growth, cell adhesion, regulation of adipogenesis, and appetite. In conclusion, this study is the first to describe a GWAS conducted in beef cattle in Mexico and represents a basis for further and future research. This study detected new QTL associated with growth traits and identified 5 positional and functional candidate genes that are potentially involved in variations of the analyzed traits. Future analyses of these regions could help to identify useful markers for marker-assisted selection and will contribute to the knowledge of the genetic basis of growth in cattle and be a foundation for genomic predictions in Mexican Charolais cattle.

Genetic shifts in the transition from wild to farmed white-tailed deer (Odocoileus virginianus) population

The white-tailed deer (Odocoileus virginianus) is one of the most important species related to sport hunting in northern Mexico. During the last decade, this species has been subjected to intensive breeding to achieve improvements in certain desired traits (i.e., antlers). This alleged intensive management of bringing originally wild populations into captivity might have harmful consequences on genetic diversity. In this short research paper we estimate and discuss the consequences of that transition, as assessed by a microsatellite genetic marker analysis. The results show that no short-term changes in genetic diversity parameters were promoted by captivity; however, a genetic diversity condition maintained by artificial genetic flow was identified, perhaps allowing for the required introgression of gene diversity into this closed population. A wider analysis is recommended and the implications are discussed. Within a realistic forecast of expanding sport hunting, the achievement of useful, pragmatic, and strict conservancy programs of this species, considering approaches such as those used here, will be necessary.

Bovine dopamine receptors DRD1, DRD4, and DRD5: genetic polymorphisms and diversities among ten cattle breeds.

The aim of this study was to analyze the allelic frequency distribution and segregation among breeds and/or between different cattle genetic groups of four novel single nucleotide polymorphisms of the bovine DRD1 and DRD5 genes and one reported SNP from the DRD4 gene. One hundred and nine-animals from ten different cattle breeds were genotyped and allelic frequencies for each locus were estimated. There were significant differences in the allelic frequencies (P < 0.05) among breeds for the DRD1 and DRD5 markers. The allelic frequencies for markers DRD1-825A>G and DRD5-378C>T were also significantly different between groups differing in genetic background. Because differences in temperament have been reported between Bos taurus taurus and B. taurus indicus breeds and their crosses, further studies are needed to investigate if any association exists between described markers and cattle behavior traits.

Genetic parameters and non-genetic influences related to birth weight in farmed white-tailed deer

Studying and understanding the sources of variation in early life traits in farmed deer are fundamental for management and/or breeding purposes. Data from a captive white-tailed deer population were analysed to identify non-genetic and genetic factors affecting the birth weight (BW) of fawns. The year, type of birth and sex were included in a fixed linear model to examine their significance. All of the examined non-genetic factors had a highly significant effect on BW ( P P P c 2 =0·15±0·062). The results support the importance of certain environmental factors affecting BW and indicate the relevance of direct genetic and maternal environmental influences to sustained genetic changes in BW and positively correlated traits in farmed white-tailed deer populations.

Screening genetic diseases prevalence in Braunvieh cattle

Heritable abnormalities can cause a reduction in productive performance, structural defects, or death of the animal. There are reports of hereditary abnormalities in Braunvieh cattle from several countries, but no evidence was found on their existence in Mexico. In this study, 28 genes associated with hereditary diseases were screened with the GGP-LD 30K array (GeneSeek®) in 300 Mexican registered Braunvieh animals. Allelic frequencies of the markers associated with illness were obtained for the following: citrullinaemia, spinal dysmyelination, spinal muscular atrophy, Brows Swiss fertility haplotype 2, congenital muscular dystonia, epidermolysis bullosa, Pompes, maple syrup urine, syndactyly, Weaver syndrome, crooked tail, deficiency of uridine monophosphate synthase, hypotrichosis, Marfan syndrome, and weak calf syndrome. The allelic frequency values were low for all the analysed loci (from 0.0015 to 0.0110), with exception of syndactyly (0.4145). Although homozygous animals for these genetic conditions were detected, no physical or physiological abnormalities associated with the clinical form of the diseases were observed in the sampled animals. Markers associated with a crooked tail, deficiency of uridine monophosphate synthase, hypotrichosis, Marfan syndrome, and weak calf syndrome were absent. The studied Mexican Braunvieh population does not present clinical or subclinical effects for ten diseases in homozygous animals. However, since the assessed animals are considered as breeding stock, the monitoring of carrier animals might be periodically necessary.