Hereford Cattle Research Articles

Genetic parameters and accuracy of traditional and genomic breeding values for eye pigmentation, hair coat and breed standard in Hereford and Braford cattle

The objectives of this research were to estimate genetic parameters using a threshold animal model by traditional (pedigree and phenotype) and single-step genomic BLUP methodologies, and assess breeding value accuracy gains with the inclusion of genomic information for eye pigmentation (EP), hair coat at weaning (HW) and yearling (HY) and breed standard (BS) in Hereford and Braford cattle. The relationship of these traits with tick resistance was also evaluated. The data used in this study were obtained from Conexão Delta G breeding program and belong to animals born between 1991 and 2014, totaling 169,839 individuals in the pedigree data, 73,615 phenotypes for EP, 81,043 for HW, 41,390 for HY, 28,186 for BS and 16,621 for tick count (TC). The genotypic data, after quality control, retained 41,011 SNP markers and 3,954 samples, including 2841 Braford and 909 Hereford animals with phenotypic records for at least one of the considered traits. Estimated heritabilities through traditional and genomic methods ranged from high to medium magnitude, being, respectively 0.46 ± 0.02 and 0.46 ± 0.02 for EP, 0.44 ± 0.03 and 0.44 ± 0.03 for HW, 0.42 ± 0.02 and 0.41 ± 0.02 for HY and 0.33 ± 0.02 and 0.32 ± 0.02 for BS. Genetic correlations among all traits were of low magnitude (-0.23 < rg < 0.29), except between HW and HY (0.62). The use of genomic information provided higher accuracy levels with gains of 0.28 and 0.14 for EP, 0.13 and 0.07 for HW, 0.16 and 0.30 for HY and 0.10 and 0.04 for BS traits, respectively considering k-means and random grouping cross-validation strategies. Thus, it is possible to obtain genetic gains in adaptation through selection for the studied traits. High genetic correlation between the hair coat evaluated at weaning and yearling indicates that selection for these traits can be performed in advance at weaning. Although low, the favorable correlations between adaptation traits favors the selection of animals that are more adapted to the tropical environmental conditions, using correlated responses to increased eye pigmentation and reduced hair coat and tick count simultaneously. The prediction of breeding values using genomic information by the single-step method should result in more accurate predictions compared to traditional pedigree evaluations.

ЗАВИСИМОСТЬ УПИТАННОСТИ МЯСНОГО СКОТА ОТ ЖИВОЙ МАССЫ И ЕЁ КОРРЕКЦИЯ УРОВНЕМ КОРМЛЕНИЯ

The purpose of the research is to increase the economic efficiency of beef production by the system of cow – calf by adjusting the feeding taking into account the point assessment of fatness of meat cows. For the effective production of beef is not enough to have highly productive animals and high quality feed. It is necessary to organize their rational use of feed. In technological groups animals have different live weight, and norms of feeding of meat cattle are calculated, generally, depending on live weight of animals. This is the wrong approach, because in the group (in the herd) animals can have the same living mass and have different energy requirements depending on the state of fatness. Adjusting the level of feeding depending on the fatness of animals will save expensive feed, as in the structure of the cost of beef a large share of the cost falls on feed (about 60%). In the course of the research, a high positive relationship between the live mass and the point assessment of the cows fatness (r=0.93 for Hereford and r= 0.95 for the Kazakh white-headed breed) was established, which allowed to determine the regression coefficients between the features. It is found that increasing body condition by 1 point increases the live weight of Hereford cattle 40.4 kg and in cows of Kazakh white-headed breed of 48.1 kg. This allowed us to determine the required changes in the feeding level for 90-100 days prior to calving to increase for cows with a body condition score of 1 by 3.02; 2 points – 2.67 to 3.02; 3 points on 1.70-2.55; 4 points at 1.32-1.70; 5-6 points to 0.85-0.91 EKE, for cows with a body condition score of 8 to reduce the level of feeding of 0.47-0.85 and EKE with fatness 9 points lower on 0,85-1,70 ECE. Thus, studies show that the organization of feeding depending on the condition, is a necessary tool for achieving economic efficiency of beef production on the system cow-calf.

1 Comparison of Linear Mixed Model and Random Regression Model for Weaning Weight in Hereford Cattle over a United States Longitudinal Gradient.

1 Comparison of Linear Mixed Model and Random Regression Model for Weaning Weight in Hereford Cattle over a United States Longitudinal Gradient.

Molecular characterization of the vitamin D receptor (VDR) gene in Holstein cows

Vitamin D plays a vital role in calcium homeostasis, growth, and immunoregulation. Because little is known about the vitamin D receptor (VDR) gene in cattle, the aim of the present investigation was to present the molecular characterization of exons 5 and 6 of the VDR gene in Holstein cows. DNA extraction, genomic sequencing, phylogenetic analysis, synteny mapping and single nucleotide gene polymorphism analysis of the VDR gene were performed to assess blood samples collected from 50 clinically healthy Holstein cows. The results revealed the presence of a 450-base pair (bp) nucleotide sequence that resembled exons 5 and 6 with intron 5 enclosed between these exons. Sequence alignment and phylogenetic analysis revealed a close relationship between the sequenced VDR region and that found in Hereford cattle. A close association between this region and the corresponding region in small ruminants was also documented. Moreover, a single nucleotide polymorphism (SNP) that caused the replacement of a glutamate with an arginine in the deduced amino acid sequence was detected at position 7 of exon 5. In conclusion, Holstein and Hereford cattle differ with respect to exon 5 of the VDR gene. Phylogenetic analysis of the VDR gene based on nucleotide sequence produced different results from prior analyses based on amino acid sequence.

Analyses of reaction norms reveal new chromosome regions associated with tick resistance in cattle

Despite single nucleotide polymorphism (SNP) availability and frequent cost reduction has allowed genome-wide association studies even in complex traits as tick resistance, the use of this information source in SNP by environment interaction context is unknown for many economically important traits in cattle. We aimed at identifying putative genomic regions explaining differences in tick resistance in Hereford and Braford cattle under SNP by environment point of view as well as to identify candidate genes derived from outliers/significant markers. The environment was defined as contemporary group means of tick counts, since they seemed to be the most appropriate entities to describe the environmental gradient in beef cattle. A total of 4363 animals having tick counts (n=10 673) originated from 197 sires and 3966 dams were used. Genotypes were acquired on 3591 of these cattle. From top 1% SNPs (410) having the greatest effects in each environment, 75 were consistently relevant in all environments, which indicated SNP by environment interaction. The outliers/significant SNPs were mapped on chromosomes 1, 2, 5, 6, 7, 9, 11, 13, 14, 15, 16, 18, 21, 23, 24, 26 and 28, and potential candidate genes were detected across environments. The presence of SNP by environment interaction for tick resistance indicates that genetic expression of resistance depends upon tick burden. Markers with major portion of genetic variance explained across environments appeared to be close to genes with different direct or indirect functions related to immune system, inflammatory process and mechanisms of tissue destruction/repair, such as energy metabolism and cell differentiation.

The effect of polymorphism within exon 12 of IGF1R gene on meat production traits in Limousin and Hereford cattle

The effect of polymorphism within exon 12 of IGF1R gene on meat production traits in Limousin and Hereford cattle

Genetic parameters for carcass and ultrasound traits in Hereford and admixed Simmental beef cattle: Accuracy of evaluating carcass traits.

Genetic parameters are required to evaluate carcass merit using correlated real-time ultrasound (RTU) measurements. Many registered bulls and heifers are measured using RTU before consideration for selection as parents, whereas few animals are recorded for carcass traits and those are often crossbred steers. The objective of this study was to estimate genetic parameters required for evaluating carcass merit in the American Hereford Association (AHA) and the American Simmental Association (ASA) using multivariate models and to assess accuracy of carcass trait estimated breeding values (EBV) for selection candidates. All available carcass data including carcass weight (CWT), fat thickness (FAT), longissimus muscle area (LMA), and marbling score (MRB) were provided by the AHA and the ASA along with RTU data including fat thickness (UFAT), longissimus muscle area (ULMA), and percentage of intramuscular fat (UIMF). Carcass data comprised 6,054 AHA and 9,056 ASA cattle, while RTU data in comparable numbers from close relatives comprised 6,074 AHA and 7,753 ASA cattle. Pedigrees included 33,226 AHA and 37,665 ASA animals. Fixed effects for carcass and RTU data included contemporary group, age at scan/slaughter, and major breed percentages. Restricted maximum likelihood procedures were applied to all the carcass and RTU measurements, along with birth weight to account for selection, fitting 8-trait multivariate models separately for each breed association. Heritability estimates for AHA and ASA carcass traits were 0.41 ± 0.04 and 0.25 ± 0.03 for FAT, 0.47 ± 0.04 and 0.32 ± 0.03 for LMA, 0.48 ± 0.04 and 0.43 ± 0.04 for MRB, 0.51 ± 0.04 and 0.34 ± 0.03 for CWT, and for RTU traits were 0.29 ± 0.04 and 0.37 ± 0.03 for UFAT, 0.31 ± 0.04 and 0.44 ± 0.03 for ULMA, and 0.45 ± 0.04 and 0.42 ± 0.03 for UIMF. Genetic correlations for AHA and ASA analyses between FAT and UFAT were 0.74 ± 0.08 and 0.28 ± 0.13, between LMA and ULMA were 0.81 ± 0.07 and 0.57 ± 0.10, and between MRB and UIMF were 0.54 ± 0.08 and 0.73 ± 0.07. Predictions of carcass merit using RTU measurements in Hereford cattle would be more reliable for FAT and LMA than MRB, but the reverse would be true for admixed Simmental cattle. Genetic correlations for MRB in AHA and for FAT and LMA in ASA are less than currently assumed in their national evaluations. Collection of greater numbers of carcass measurements would improve the accuracy of genetic evaluations for carcass traits in both breeds.

Genotype by environment interaction effects in genetic evaluation of preweaning gain for Line 1 Hereford cattle from Miles City, Montana1

Genotype by environment interaction effects in genetic evaluation of preweaning gain for Line 1 Hereford cattle from Miles City, Montana1

Economic selection indexes for Hereford and Braford cattle raised in southern Brazil.

Economic selection indexes (EI) are considered the best way to select the most profitable animals for specific production systems. Nevertheless, in Brazil, few genetic evaluation programs deliver such indexes to their breeders. The aims of this study were to determine the breeding goals (BG) and economic values (EV, in US$) for typical beef cattle production systems in southern Brazil, to propose EI aimed to maximize profitability, and to compare the proposed EI with the currently used empirical index. Bioeconomic models were developed to characterize 3 typical production systems, identifying traits of economic impact and their respective EV. The first was called the calf-crop system and included the birth rate (BR), direct weaning weight (WWd), and mature cow weight (MCW) as selection goals. The second system was called the full-cycle system, and its breeding goals were BR, WWd, MCW, and carcass weight (CW). Finally, the third was called the stocking and finishing system, which had WWd and CW as breeding goals. To generate the EI, we adopted the selection criteria currently measured and used in the empirical index of PampaPlus, which is the genetic evaluation program of the Brazilian Hereford and Braford Association. The comparison between the EI and the current PampaPlus index was made by the aggregated genetic-economic gain per generation (Δ). Therefore, for each production system an index was developed using the derived economic weights, and it was compared with the current empirical index. The relative importance (RI) for BR, WWd, and MCW for the calf-crop system was 68.03%, 19.35%, and 12.62%, respectively. For the full-cycle system, the RI for BR, WWd, MCW, and CW were 69.63%, 7.31%, 5.01%, and 18.06%, respectively. For the stocking and finishing production system, the RI for WWd and CW was 34.20% and 65.80%, respectively. The Δ for the calf-crop system were US$6.12 and US$4.36, using the proposed economic and empirical indexes, respectively. Respective values were US$19.87 and US$18.22 for the full-cycle system and US$20.52 and US$18.52 in the stocking and finishing system. The efficiency of the proposed EI had low sensitivity to changes in the values of the economic and genetic parameters. The 3 EI generated higher Δ when using the proposed economic weight compared to the Δ provided by a PampaPlus index, suggesting the use of proposed EI to obtain greater economic profitability in relation to the current empirical PampaPlus index.

Tag SNP selection for prediction of tick resistance in Brazilian Braford and Hereford cattle breeds using Bayesian methods

BackgroundCattle resistance to ticks is known to be under genetic control with a complex biological mechanism within and among breeds. Our aim was to identify genomic segments and tag single nucleotide polymorphisms (SNPs) associated with tick-resistance in Hereford and Braford cattle. The predictive performance of a very low-density tag SNP panel was estimated and compared with results obtained with a 50 K SNP dataset.ResultsBayesB (π = 0.99) was initially applied in a genome-wide association study (GWAS) for this complex trait by using deregressed estimated breeding values for tick counts and 41,045 SNP genotypes from 3455 animals raised in southern Brazil. To estimate the combined effect of a genomic region that is potentially associated with quantitative trait loci (QTL), 2519 non-overlapping 1-Mb windows that varied in SNP number were defined, with the top 48 windows including 914 SNPs and explaining more than 20% of the estimated genetic variance for tick resistance. Subsequently, the most informative SNPs were selected based on Bayesian parameters (model frequency and t-like statistics), linkage disequilibrium and minor allele frequency to propose a very low-density 58-SNP panel. Some of these tag SNPs mapped close to or within genes and pseudogenes that are functionally related to tick resistance. Prediction ability of this SNP panel was investigated by cross-validation using K-means and random clustering and a BayesA model to predict direct genomic values. Accuracies from these cross-validations were 0.27 ± 0.09 and 0.30 ± 0.09 for the K-means and random clustering groups, respectively, compared to respective values of 0.37 ± 0.08 and 0.43 ± 0.08 when using all 41,045 SNPs and BayesB with π = 0.99, or of 0.28 ± 0.07 and 0.40 ± 0.08 with π = 0.999.ConclusionsBayesian GWAS model parameters can be used to select tag SNPs for a very low-density panel, which will include SNPs that are potentially linked to functional genes. It can be useful for cost-effective genomic selection tools, when one or a few key complex traits are of interest.

Tick resistance genetic parameters and its correlations with production traits in Hereford and Braford cattle

Inclusion of cattle genetic resistance to ticks in selection programs represents an auxiliary method in strategic control of this parasite. This study was conducted to estimate genetic parameters for cattle tick resistance measured by tick counting on the inner hind legs region (TCHL) and on one side of body (TCBS) of Hereford and Braford cattle naturally exposed to ticks in southern Brazil. Records of weight gain from birth to weaning (WG), visual scores of conformation, precocity and muscling at weaning (WC, WP and WM, respectively) and at yearling (YC, YP and YM, respectively), weight gain from weaning to yearling (YG) and scrotal circumference (SC) were also analyzed to obtain correlations among all the traits. Heritability estimates obtained by bivariate analysis were TCHL = 0.13 and TCBS = 0.17 and phenotypic correlation between both methods was 0.09 (P<0.05). Repeatability estimate for TCBS was 0.29. Heritability estimates obtained by multivariate analysis were TCBS = 0.19; WG = 0.35; WC = 0.28; WP = 0.23; WM = 0.26; YG = 0.14; YC = 0.18; YP = 0.18; YM = 0.18; and SC = 0.43. No unfavorable genetic correlations among TCBS and growth traits and visual scores at different ages and scrotal circumference have been identified, indicating that simultaneous selection for improving all the traits is feasible.

A fine structure genetic analysis evaluating ecoregional adaptability of a Bos taurus breed (Hereford).

Ecoregional differences contribute to genetic environmental interactions and impact animal performance. These differences may become more important under climate change scenarios. Utilizing genetic diversity within a species to address such problems has not been fully explored. In this study Hereford cattle were genotyped with 50K Bead Chip or 770K Bovine Bead Chip to test the existence of genetic structure in five U.S. ecoregions characterized by precipitation, temperature and humidity and designated: cool arid (CA), cool humid (CH), transition zone (TZ), warm arid (WA), and warm humid (WH). SNP data were analyzed in three sequential analyses. Broad genetic structure was evaluated with STRUCTURE, and ADMIXTURE software using 14,312 SNPs after passing quality control variables. The second analysis was performed using principal coordinate analysis with 66 Tag SNPs associated in the literature with various aspects of environmental stressors (e.g., heat tolerance) or production (e.g., milk production). In the third analysis TreeSelect was used with the 66 SNPs to evaluate if ecoregional allelic frequencies deviated from a central frequency and by so doing are indicative of directional selection. The three analyses suggested subpopulation structures associated with ecoregions from where animals were derived. ADMIXTURE and PCA results illustrated the importance of temperature and humidity and confirm subpopulation assignments. Comparisons of allele frequencies with TreeSelect showed ecoregion differences, in particular the divergence between arid and humid regions. Patterns of genetic variability obtained by medium and high density SNP chips can be used to acclimatize a temperately derived breed to various ecoregions. As climate change becomes an important factor in cattle production, this study should be used as a proof of concept to review future breeding and conservation schemes aimed at adaptation to climatic events.

Genetic Structure of Populations of Kazakh Whiteheaded and Hereford Cattles on the Basis of Microsatellite DNA

This work is aimed at determination of genetic dissimilarities between two allied cattle breeds: Kazakh Whiteheaded and Hereford. Hair follicles were analyzed, from which DNA was extracted with subsequent amplification. Identification of amplification products was performed using an ABI Prism 310 genetic analyzer. Allele 147 was detected in Kazakh Whiteheaded cattle in locus BM 2113, there was no such allele in Hereford cattle. Average number of alleles per one locus of Hereford and Kazakh Whiteheaded breeds was 11.82 and 12.27, respectively. Herewith, the number of private alleles in Kazakh Whiteheaded cattle was 10 and in Herefordcattle-11. No confidential difference in average heterozygosity was determined. Analysis of sample allele fund with regard to both considered breeds revealed the characteristics’ range for both of them, thus facilitating determination of genetic dissimilarity between the two breeds.

Genotype x environment interaction on post-weaning performance and carcass in beef cattle

We analyzed average daily gain from weaning to yearling (ADG), yearling weight (YW), rib eye area, and subcutaneous fat thickness of 91 Angus, Hereford, Caracu, and Nellore cattle, and their crosses. The animals were split into two grazing groups: improved natural grassland (n = 47) and natural grassland (n = 44). The environment was found to influence all traits, and the highest measures of performance were observed in improved natural grassland. The genetic group x environment interaction was verified only for ADG and YW (P &lt; 0.05). We found the best performance trait averages for crossbreeds of Bos taurus and Bos indicus. In addition, we found genetic x environment interaction effects in growing traits and Longissimus muscle area between the evaluated genotype groups. Finally, we found that between the evaluated genotype groups, subcutaneous adipose fat was not influenced by the environment.

ЭКСТЕРЬЕР И ВОСПРОИЗВОДИТЕЛЬНАЯ СПОСОБНОСТЬ ГЕРЕФОРДСКОГО СКОТА АВСТРАЛИЙСКОЙ СЕЛЕКЦИИ ПРИ АККЛИМАТИЗАЦИИ В УСЛОВИЯХ БАШКОРТОСТАНА

The main object of our research was to determine the characteristics of the exterior and the reproductive capacity of the Australian breeding Hereford cattle in the process of acclimatization in the Ural steppe and forest steppe zones of Bashkortostan. The object of research is the cattle of Australian origin, brought winter 2009 GUSP MTS «Central» and LLC «Agro-SAVA-Usen», located in the Ural steppe and steppe zones of the Republic Bashkortostan. The scientific and economic indicators examined experiences of live weight during the first three years of acclimatization (2010-2012 gg.), Analyzed the data of linear and volumetric measurements for which the index is calculated body. Evaluation animals in conformation based on the study of body type characteristics, taking into account the ratio of body parts to each other. The study of conformation and constitution of farmed animals by taking individual body measurements and calculation of body index gives an indication of the intensity of their linear growth depending on the sex and acclimatization period. The reproductive ability of cows was estimated duration between ewes period and the service period, the output of calves per hundred ewes, in terms of body weight of newborn calves. The studies found that in the process of acclimatization there was a significant (P<0.05) increase in live weight of cows at 10.51% and 26.94% for the bulls that show an adaptive plasticity of imported livestock. The evaluation of the exterior and build the amount of balls in bulls was in the range of 18-20, the core of breeding cows – 22-24, which corresponds to the requirements of the elite class and the elite-record. For three years the duration of the acclimatization between ewes period decreased an average of livestock under study for 7 days, the service period – 8 days. Out of calves in the second year of acclimatization has increased by 2.51% and was significantly increased (P <0.05) for the third year at 7.73%. Thus, on the basis of the parameters was studied, it is possible to conclude that high acclimatization abilities Hereford cattle of Australian origin to the conditions of the Ural steppe and forest steppe zones.

Design of selection schemes to include tick resistance in the breeding goal for Hereford and Braford cattle.

Ticks are one of the main causes of losses in cattle, causing economic impact by reducing productivity and fertility and by transmission of diseases. The objective of this study was to analyze the genetic gains obtained through different strategies to include traditional (EBV) or genomic EBV (GEBV) for tick count (TC) in selection indexes for Hereford and Braford cattle. Besides TC, we also considered traits currently included in the Delta G Breeding Program Index (DGI): preweaning gain, weaning conformation, weaning precocity, weaning muscling, postweaning gain, yearling conformation, yearling precocity, yearling muscling, and scrotal circumference. Genetic gain per generation (ΔG) was evaluated using the current DGI and including TC in 8 alternative scenarios with TC relative weightings of 10, 50, or 100% and using phenotype or GEBV. Genomic EBV accuracy () ranged between 0.1 and 0.9. As expected, increasing increases the accuracy of the index () for all scenarios in which GEBV were considered. As the relative weight of TC was increased to 50%, greater ΔG differences in relation to the baseline DGI ($53.03) scenario were observed when the GEBV information was included with equal to or greater than 0.7 only for TC (ΔG between $61.06 and $74.26) or equal to or greater than 0.5 for all traits (ΔG between $56.03 and $83.36). To achieve these accuracies for traits with low heritability, a large calibration data set would be required. Focusing only on TC, the availability of genomic information would be desirable to avoid the need to count ticks and the exposure of animals to parasitism risks. However, for = 0.7, the respective numbers for Hereford and Braford would be 4,703 and 6,522 animals. As expected, when comparing the relative index weights of 10, 50, and 100% for TC, the highest response to selection per generation (RS) for TC was in the scenario was with 100% relative weight and GEBV for this trait (SR = -0.09 SD with = 0.9). This would be the recommended scenario to form tick-resistant lines in Hereford and Braford cattle. However, with 50% relative weight for TC, including GEBV information for TC only or for all traits in index ( = 0.9), it should yield 93 or 84% of RS, respectively, compared to that obtained with full emphasis on TC (100% relative weight) and GEBV information. This indicates that in the presence of highly accurate GEBV, despite slightly slower gain for TC, indexes with 50% relative weight for TC are interesting alternatives to jointly improve tick resistance and other relevant traits.

Ultra-low-density genotype panels for breed assignment of Angus and Hereford cattle

Angus and Hereford beef is marketed internationally for apparent superior meat quality attributes; DNA-based breed authenticity could be a useful instrument to ensure consumer confidence on premium meat products. The objective of this study was to develop an ultra-low-density genotype panel to accurately quantify the Angus and Hereford breed proportion in biological samples. Medium-density genotypes (13 306 single nucleotide polymorphisms (SNPs)) were available on 54 703 commercial and 4042 purebred animals. The breed proportion of the commercial animals was generated from the medium-density genotypes and this estimate was regarded as the gold-standard breed composition. Ten genotype panels (100 to 1000 SNPs) were developed from the medium-density genotypes; five methods were used to identify the most informative SNPs and these included the Delta statistic, the fixation (Fst) statistic and an index of both. Breed assignment analyses were undertaken for each breed, panel density and SNP selection method separately with a programme to infer population structure using the entire 13 306 SNP panel (representing the gold-standard measure). Breed assignment was undertaken for all commercial animals (n=54 703), animals deemed to contain some proportion of Angus based on pedigree (n=5740) and animals deemed to contain some proportion of Hereford based on pedigree (n=5187). The predicted breed proportion of all animals from the lower density panels was then compared with the gold-standard breed prediction. Panel density, SNP selection method and breed all had a significant effect on the correlation of predicted and actual breed proportion. Regardless of breed, the Index method of SNP selection numerically (but not significantly) outperformed all other selection methods in accuracy (i.e. correlation and root mean square of prediction) when panel density was ⩾300 SNPs. The correlation between actual and predicted breed proportion increased as panel density increased. Using 300 SNPs (selected using the global index method), the correlation between predicted and actual breed proportion was 0.993 and 0.995 in the Angus and Hereford validation populations, respectively. When SNP panels optimised for breed prediction in one population were used to predict the breed proportion of a separate population, the correlation between predicted and actual breed proportion was 0.034 and 0.044 weaker in the Hereford and Angus populations, respectively (using the 300 SNP panel). It is necessary to include at least 300 to 400 SNPs (per breed) on genotype panels to accurately predict breed proportion from biological samples.

Genotype by environment interaction effects in genetic evaluation of preweaning gain for Line 1 Hereford cattle from Miles City, Montana

It has long been recognized that genotype × environment interaction potentially influences genetic evaluation of beef cattle. However, this recognition has largely been ignored in systems for national cattle evaluation. The objective of this investigation was to determine if direct and maternal genetic effects on preweaning gain would be reranked depending on an environmental gradient as determined by year effects. Data used were from the 76-yr selection experiment with the Line 1 Hereford cattle raised at Miles City, MT. The data comprised recorded phenotypes from 7,566 animals and an additional 1,862 ancestral records included in the pedigree. The presence of genotype × environment interaction was examined using reaction norms wherein year effects on preweaning gain were hypothesized to linearly influence the EBV. Estimates of heritability for direct and maternal effects, given the average environment, were 10 ± 2 and 26 ± 3%, respectively. In an environment that is characterized by the 5th (95th) percentile of the distribution of year effects, the corresponding estimates of heritability were 18 ± 3 (22 ± 3%) and 30 ± 3% (30 ± 3%), respectively. Rank correlations of direct and maternal EBV appropriate to the 5th and 95th percentiles of the year effects were 0.67 and 0.92, respectively. In the average environment, the genetic trends were 255 ± 1 g/yr for direct effects and 557 ± 3 g/yr for maternal effects. In the fifth percentile environment, the corresponding estimates of genetic trend were 271 ± 1 and 540 ± 3 g/yr, respectively, and in the 95th percentile environment, they were 236 ± 1 and 578 ± 3 g/yr, respectively. Linear genetic trends in environmental sensitivity were observed for both the direct (-8.06 × 10 ± 0.49 × 10) and maternal (8.72 × 10 ± 0.43 × 10) effects. Therefore, changing systems of national cattle evaluation to more fully account for potential genotype × environment interaction would improve the assessment of breeding stock, particularly for direct effects. Estimates of environmental sensitivity parameters could also facilitate identification of genetic limitations to production.

Economic selection indexes for Hereford and Braford cattle raised in southern Brazil

Economic selection indexes for Hereford and Braford cattle raised in southern Brazil

Design of selection schemes to include tick resistance in the breeding goal for Hereford and Braford cattle

Design of selection schemes to include tick resistance in the breeding goal for Hereford and Braford cattle