Crossbreeding System Research Articles

186 The effect of breeding program on cow maintenance requirement and efficiency of calf growth

Abstract With genetic tools available today, it is possible to select for traits within breed to achieve similar production phenotypes. Our hypothesis was that biological efficiency of preweaning calf growth would be improved with crossbreeding when dams were selected for similar mature frame size, weight, growth, and milk production. The objective of this study was to determine maintenance energy requirements and efficiency of calf growth through weaning for Angus and Hereford x Angus crossbred cows selected for similar mature BW, growth, and milk production potential. Fifty-nine Angus (n = 32) and Hereford x Angus (n = 27) cow/ calf pairs were assigned to four pen replicates per breed. Cows and calves were limit-fed for a 21-d adaptation period followed by an 84-d experimental period to achieve BW and BCS stasis. Calves did not have access to cow’s feed and daily calf feed allotment was adjusted biweekly to provide 1.25% of previous week’s mean BW. There were no differences due to breed in cow hip height, BW, milk yield (P > 0.31),or cow maintenance energy requirement (P = 0.54). Milk from Hereford-sired cows was slightly more concentrated in energy (P = 0.05) and Hereford-sired cows had greater BCS and ultrasound rib fat and rump fat (P < 0.05) throughout the experiment. Calves from Angus dams were heavier (P 0.01) at the initiation of the experiment, although there were no differences in ADG, final BW, or adjusted weaning BW (P ≥ 0.24). Efficiency of calf growth was not different when expressed as calf BW gain to calf feed and milk energy consumed or as cow/calf pair feed intake or energy intake per unit of calf BW gain (P ≥ 0.31). While the crossbreeding system did not improve biological efficiency of calf growth, more research is necessary to determine if increased cow BCS is advantageous

1 The effect of breeding system on voluntary forage consumption of beef cows

Abstract Recent genetic trends in beef breeds suggest an imbalance in the selection of output and input traits. The inverse relationship between cow maintenance requirements with output traits such as growth and milk production may have ramifications on carrying costs of cows as well as feed intake of the cow herd. One method commonly used to maximize efficiency within a production system is to utilize a crossbreeding system to capitalize on breed complementarity. The objective of this study was to investigate the impact of breeding system on forage intake and determine correlations between breeding system, dry matter intake, and maintenance requirements of beef cows. To do this, a 45-d feeding trial was conducted using 59 pregnant, non-lactating Angus (ANG; n = 32) and Hereford x Angus (HA; n = 27) cows similar in mature BW, growth, and milk potential. Animals were assigned to pen based on breed with four pen replicates per breed. Cows were housed in dry-lot pens equipped with shade, windbreaks, and feed bunks with free-choice access to clean water. A chopped hay ration (65% DM, 55.7% TDN, 7.8% CP) was provided ad libitum to determine forage intake. Daily intake tended to be lower (P = 0.06) for HA compared to ANG (134.25 g/kg MBW ANG; 125.37 g/kg MBW HA). There was no difference in BW at initiation or conclusion of the trial, however, HA sustained greater BCS throughout the duration of the study (P > 0.01). After accounting for differences in retained energy, there was no detectable differences in maintenance requirements (P = 0.11). Results of this study suggest lower forage intake of crossbred cattle and suggests potential differences in energy prioritization and partitioning between breeds.

177 The effect of breeding system on voluntary forage consumption of beef cows

Abstract Recent genetic trends in beef breeds suggest an imbalance in the selection of output and input traits. The inverse relationship between cow maintenance requirements with output traits such as growth and milk production may have ramifications on carrying costs of cows as well as feed intake of the cow herd. One method commonly used to maximize efficiency within a production system is to utilize a crossbreeding system to capitalize on breed complementarity. The objective of this study was to investigate the impact of breeding system on forage intake and determine correlations between breeding system, dry matter intake, and maintenance requirements of beef cows. To do this, a 45-d feeding trial was conducted using 59 pregnant, non-lactating Angus (ANG; n = 32) and Hereford x Angus (HA; n = 27) cows similar in mature BW, growth, and milk potential. Animals were assigned to pen based on breed with four pen replicates per breed. Cows were housed in dry-lot pens equipped with shade, windbreaks, and feed bunks with free-choice access to clean water. A chopped hay ration (65% DM, 55.7% TDN, 7.8% CP) was provided ad libitum to determine forage intake. Daily intake tended to be lower (P = 0.06) for HA compared to ANG (134.25 g/kg MBW ANG; 125.37 g/kg MBW HA). There was no difference in BW at initiation or conclusion of the trial, however, HA sustained greater BCS throughout the duration of the study (P > 0.01). After accounting for differences in retained energy, there were no detectable differences in maintenance requirements (P = 0.11). Results of this study suggest lower forage intake of crossbred cattle and suggests potential differences in energy prioritization and partitioning between breeds.

Genomic Evaluation for a Crossbreeding System Implementing Breed-of-Origin for Targeted Markers.

The genome in crossbred animals is a mosaic of genomic regions inherited from the different parental breeds. We previously showed that effects of haplotypes strongly associated with crossbred performance are different depending upon from which parental breed they are inherited, however, the majority of the genomic regions are not or only weakly associated with crossbred performance. Therefore, our objective was to develop a model that distinguishes between selected single nucleotide polymorphisms (SNP) strongly associated with crossbred performance and all remaining SNP. For the selected SNP, breed-specific allele effects were fitted whereas for the remaining SNP it was assumed that effects are the same across breeds (SEL-BOA model). We used data from three purebred populations; S, LR, and LW, and the corresponding crossbred population. We selected SNP that explained together either 5 or 10% of the total crossbred genetic variance for average daily gain in each breed of origin. The model was compared to a model where all SNP-alleles were allowed to have different effects for crossbred performance depending upon the breed of origin (BOA model) and to a model where all SNP-alleles had the same effect for crossbred performance across breeds (G model). Across the models, the heritability for crossbred performance was very similar with values of 0.29–0.30. With the SEL-BOA models, in general, the purebred-crossbred genetic correlation (rpc) for the selected SNP was larger than for the non-selected SNP. For breed LR, the rpc for selected SNP and non-selected SNP estimated with the SEL-BOA 5% and SEL-BOA 10% were very different compared to the rpc estimated with the G or BOA model. For breeds S and LW, there was not a big discrepancy for the rpc estimated with the SEL-BOA models and with the G or BOA model. The BOA model calculates more accurate breeding values of purebred animals for crossbred performance than the G model when rpc differs (≈10%) between the G and the BOA model. Superiority of the SEL-BOA model compared to the BOA model was only observed for SEL-BOA 10% and when rpc for the selected and non-selected SNP differed both (≈20%) from the rpc estimated by the G or BOA model.

Economic weights of maternal and direct traits of pigs calculated by applying gene flow methods

Multiple trait selection indexes in pig breeding programmes should take into account the population structure and time delay between parent selection and expressions of traits in all production levels next to the trait impacts on economic efficiency of production systems. Gene flow procedures could be used for the correct evaluation of maternal and direct traits of pig breeds involved in breeding or crossbreeding systems. Therefore, the aim of this study was to expand a previously developed bioeconomic model and computer program to calculate the marginal economic values by including a gene flow procedure to calculate the economic weights for maternal and direct traits in pig breeds. The new program was then applied to the three-way crossbreeding system of the Czech National Programme for Pig Breeding. Using this program, the marginal economic values of traits for dam breeds Czech Large White in the dam position and Czech Landrace in the sire position, and for the sire breed Pietrain were weighted by the number of discounted gene expressions of selected parents of each breed summarised within all links of the crossbreeding system during the 8-year investment period. Economic weights calculated in this way were compared with the approximate economic weights calculated previously without a gene flow procedure. Taking into account the time delay between parent selection and trait expression (using discounting with half-year discount rates of 2% or 5%) and including more than one generation of parent progeny had little impact on the relative economic importance of maternal and direct traits of breeds involved in the evaluated three-way crossbreeding system. These results indicated that this gene-flow method could be foregone when estimating the relative economic weights of traits in pig crossbreeding systems applying artificial insemination at all production levels.

An Overview on the Concept and Utilization of Heterosis in Livestock

Heterosis or hybrid vigour is the excellence of F1 cross beyond the average performance of the two parents and noticeable across species. Heterosis, coined by Professor G.H. Shull in 1914 is well known to exploit the benefits of crossbreeding. Heterosis is usually positive but negative heterosis does occur and is uncommon. Heterosis is widely accepted to occur due to non-additive gene action i.e. dominance, over-dominance and epistasis. The heterotic effects are usually expressed in percentage and always highest in F1 generation followed by a decline in later generations. This decline is mainly due to the recombination and segregation losses. Rotational crossbreeding systems are therefore followed to maintain levels of heterosis in later generations. Estimates of heterosis are high in low heritable traits followed by moderate in moderately heritable traits and negligible in high heritable traits. Besides improvement, there are some limitations to heterosis that shall overcome shortly.

Factors influencing extent of adoption of artificial insemination (AI) technology among cattle farmers in Assam

The study was carried out to identify various socio-economic factors influencing adoption of AI technology in the crossbreeding system at the farm household level. The Tobit regression for a data set of 245 sample farmers from three districts of Assam was used. The results showed that the education of the household head, accessing support from government dairy development programme, number of years since farmers first knew about AI and proportion of net dairy income positively and significantly affect extent of adoption of AI; while factors such as, distance to nearest market and risk perception of the farmers on AI negatively and statistically significantly influence extent of adoption of AI. The findings of the study suggested a package of interventions for increasing the use intensity of AI technology. These included, more specifically, the extension support to the farmers, market linkage, conducting awareness programme and direct support to the farmers to reduce the cost of farming.

Bio-economic Model Predicts Economic Values for Beef Production

Objective: The objective was to estimate economic values for production traits in a full life cycle system using a bio-economic model with Angus purebred and a terminal crossbreeding system with Nelore sires mated to Angus dams. Study Description: Phenotypic performance data were collected from the Bifequali crossbreeding scheme at the Embrapa Pecuaria Sul Research Center of the Brazilian Agricultural Research Corporation. The data consisted of performance and carcass traits measured on progeny of Angus purebred and Nelore sires mated to Angus dams raised in a pasture-based production system from birth to slaughter (full life cycle). The economic characterization of the system was based on fixed costs and variable costs. The bio-economic was developed in ?R? programming language using the phenotypic information and the production costs. To estimate economic values, the bio-economic model was first parameterized and a base profit was calculated. The Bottom Line: The use of crossbreed animals provides an effective tool to improve important traits and system level profitability in a full life cycle beef production system.

Genomic evaluation for a three-way crossbreeding system considering breed-of-origin of alleles

BackgroundGenomic prediction of purebred animals for crossbred performance can be based on a model that estimates effects of single nucleotide polymorphisms (SNPs) in purebreds on crossbred performance. For crossbred performance, SNP effects might be breed-specific due to differences between breeds in allele frequencies and linkage disequilibrium patterns between SNPs and quantitative trait loci. Accurately tracing the breed-of-origin of alleles (BOA) in three-way crosses is possible with a recently developed procedure called BOA. A model that accounts for breed-specific SNP effects (BOA model), has never been tested empirically on a three-way crossbreeding scheme. Therefore, the objectives of this study were to evaluate the estimates of variance components and the predictive accuracy of the BOA model compared to models in which SNP effects for crossbred performance were assumed to be the same across breeds, using either breed-specific allele frequencies ({text{G}}_{text{A}} model) or allele frequencies averaged across breeds ({text{G}}_{text{B}} model). In this study, we used data from purebred and three-way crossbred pigs on average daily gain (ADG), back fat thickness (BF), and loin depth (LD).ResultsEstimates of variance components for crossbred performance from the BOA model were mostly similar to estimates from models {text{G}}_{text{A}} and {text{G}}_{text{B}}. Heritabilities for crossbred performance ranged from 0.24 to 0.46 between traits. Genetic correlations between purebred and crossbred performance ({text{r}}_{text{pc}}) across breeds ranged from 0.30 to 0.62 for ADG and from 0.53 to 0.74 for BF and LD. For ADG, prediction accuracies of the BOA model were higher than those of the {text{G}}_{text{A}} and {text{G}}_{text{B}} models, with significantly higher accuracies only for one maternal breed. For BF and LD, prediction accuracies of models {text{G}}_{text{A}} and {text{G}}_{text{B}} were higher than those of the BOA model, with no significant differences. Across all traits, models {text{G}}_{text{A}} and {text{G}}_{text{B}} yielded similar predictions.ConclusionsThe BOA model yielded a higher prediction accuracy for ADG in one maternal breed, which had the lowest {text{r}}_{text{pc}} (0.30). Using the BOA model was especially relevant for traits with a low {text{r}}_{text{pc}}. In all other cases, the use of crossbred information in models {text{G}}_{text{A}} and {text{G}}_{text{B}}, does not jeopardize predictions and these models are more easily implemented than the BOA model.

3’-UTR polymorphisms of SETD7 gene associate with economic traits in an F2 population between Landrace and Jeju (Korea) Black pigs

In order to reveal the association between genotypes of SET domain-containing protein 7; Histone H3-lysine 4-specific methyltransferase (SETD7) gene and economic traits in pigs, this study tested the association between SNP (single nucleotide polymorphism) genotypes of 3’-untranslated region of SETD7 g.1354C>T and growth and carcass traits in a resource population of the crossbred Landrace × Jeju Black pig (JBP). SETD7 T- pigs showed significantly thicker back fat levels than those of CC homozygotes (P less than 0.05). However, the levels of average daily gains, body weights, loin muscle area, marbling score, and meat colors did not show significant association (P>0.05). These results reveal faster growth rates in the late period of production, especially backfat deposition at the subcutaneous region according to genotypes of the SETD7 gene. These findings indicate that SETD7 genotypes may involve fat deposition or adipocyte differentiation and assist as molecular genetic markers for improving the JBP-related crossbreeding systems.

What does the ‘closed herd’ really mean for Australian breeding companies and their customers?

The perception that the genetic background of the Australian pig population is limiting for genetic improvement of commercial pigs in Australia is considered in the context of well established theory combined with practical evidence. The diversity of pig breeds used in modern commercial pig-breeding programs is diminished worldwide relative to all the pig breeds available. Australia is no different in this respect. The use of predominantly three main breeds (Large White, Landrace, Duroc) and synthetic lines, with contributions from other minor breeds to form the basis of a cross-breeding system for commercial pig production is well established internationally. The Australian concern of relatively small founder populations is potentially of relevance, from a theoretical perspective, for (1) the prevalence of defects or the presence of desirable alleles, and (2) the loss of genetic variation or increase in inbreeding depression resulting from increased inbreeding in closed nucleus lines, potentially reducing response to selection. However, rates of response achieved in Australian herds are generally commensurate with the performance recording and selection emphasis applied, and do not appear to be unduly restricted. Moreover, favourable alleles present in unrepresented breeds are frequently present in the three major breeds elsewhere, and therefore would be expected to be present within the Australian populations. Wider testing would provide confirmation of this. Comparison of estimates of effective population size of Australian populations with experimental selection lines overseas (e.g. INRA) or other intensely selected species (e.g. Holstein cattle) suggest adequate genetic diversity to achieve ongoing genetic improvement in the Australian pig industry. However, fitness traits should be included in breeding goals. What remains to be seen is whether novel phenotypes or genotypes are required to meet future challenges, which might be imposed by changes in the environment (e.g. climate change, disease) or market needs. Given probable overlap in genetic merit across Australian and foreign populations for unselected attributes, we suggest that sufficient genetic resources are already present in Australian herds to continue commercial progress within existing Australian populations that have adapted to Australian conditions.

Genomic clustering helps to improve prediction in a multibreed population.

Genomic prediction for crossbred beef cattle has shown limited results using low- to moderate-density SNP panels. The relationship between the training and validation populations, as well as the size of the reference population, affects the prediction accuracy for genomic selection. Rotational crossbreeding systems require the usage of crossbred animals as sires and dams of future generations, so crossbred animals require accurate evaluation. Here, a novel method for grouping of purebred and crossbred animals (based exclusively on genotypes) for genomic selection was investigated. Clustering of animals to investigate the genetic similarity among different groups was performed using several genomic relationship criteria between individuals. Hierarchical clusters based on average-link criteria (computed as the mean distance between elements of each subcluster) were formed. The accuracy of genomic prediction was assessed using 1,500 bulls genotyped for 54,609 markers. Estimated breeding values based on all available phenotypic records for birth weight, weaning gain, postweaning gain, and yearling gain were calculated using BLUP methodologies and deregressed to ensure unbiased comparisons could be made across populations. A 5-fold validation technique was used to calculate direct genomic values for all genotyped bulls; the addition of unrelated animals in the reference population was also investigated. We demonstrate a decrease in genomic selection accuracy after including animals from disconnected clusters. A method to improve genomic selection for crossbred and purebred animals by clustering animals based on their genotype is suggested. Unlike traditional approaches for genomic selection with a fixed reference population, genomic prediction using clusters (GPC) chooses the best reference population for better accuracy of genomic prediction of crossbred and purebred animals using clustering methods based on genotypes. An overall average gain in accuracy of 1.30% was noted over all scenarios across all traits investigated when the GPC approach was implemented. Further investigation is required to assess this difference in accuracy when a larger genotyped population is available, especially for the comparison of groups with higher genetic dissimilarity, such as those found in industry-wide across-breed genetic evaluations.

제주흑돼지와 랜드레이스 교배 2세대의 도체형질과 IDH3B 유전자형의 상관관계

본 연구에서는 제주흑돼지와 랜드레이스 품종 사이에서 생산된 F₂ 교배 집단의 경제형질과 isocitrate dehydrogenase 3, beta subunit (IDH3B) 유전자의 유전적 다형성의 상관관계를 시험하였다. IDH3B 유전자의 프로모터 지역에서 304-bp 삽입/결실 돌연변이를 기준으로 전체 1,105 F₂들에 유전자형 분석에 이용하였다. 기초축군과 F₁, F₂에서 세 가지 유전자형(AA, AB, BB)이 모두 발견되었다. 통계적 상관 분석결과에서 도체중(CW), 세 지점(4-5번 흉추 사이, 11-12번 흉추 사이, 13번 흉추-1번 요추 사이)에서 측정한 등지방두께와 도체장(CL)의 수준은 유전자형애 따른 유의적인 차이를 나타내었지만(p<0.05), 육색(MC), 등심단면적(EMA)과 근내지방도(MARB)은 유의적인 차이를 나타내지 않았다(p>0.05). IDH3B 동형접합자 BB를 보유한 F₂ 돼지들은 도체중이 더 무겁고(80.790±0.725 kg), 도체장은 더 짧은(101.875±0.336 cm) 양상을 보였다(p<0.05). 또한, IDH3B 유전자형 BB인 개체들은 IDH3B AA나 AB 유전자형에 비해 4-5번 흉추 사이, 11-12번 흉추 사이에서 측정된 등지방두께도 더 두꺼운 수준을 나타내었다(p<0.05). 이상의 결과들은 IDH3B의 유전적 다양성이 제주흑돼지와 랜드레이스와 관련된 교배육종 체계의 산육능력 향상을 위한 유전적 분자 표지인자로 활용될 수 있음을 나타내었다. This study tested the association between genetic polymorphisms of the isocitrate dehydrogenase 3, beta subunit (IDH3B) gene and economic traits in an F₂ crossbred population of Landrace × Jeju (South Korea) Black pigs. A 304-bp insertion/deletion mutation in promoter region was screened for determining genotypes of the IDH3B gene in a total of 1,105 F₂ pigs. Three genotypes (AA, AB, and BB) were identified in the founder, F₁, and F₂ populations. Association analysis showed significant differences in carcass weights (CW), backfat thicknesses in three positions of the body (4^th-5^th ribs, BF5; 11^th-12^th ribs, BF12; 13^th rib-1^st lumbar, BFL), and carcass lengths (CL) (p<0.05), but not in meat color (MC), eye muscle area (EMA), or marbling scores (MARB) (p>0.05). The F₂ IDH3B BB homozygotes showed heavier CW (80.790±0.725 kg) and shorter CL (101.875±0.336 cm) than the other genotypes (p<0.05). In addition, the BF levels between the 4^th - 5^th and 11^th - 12^th vertebrae were thicker in the carcasses of pigs with the IDH3B BB genotype than with the other genotypes (p<0.05). These results suggested that genetic variations in the IDH3B gene may serve as molecular genetic markers for improving the Landrace × Jeju Black pig crossbreeding systems.

Genetic parameters and crossbreeding effects of fat deposition and fatty acid profiles in Iberian pig lines.

The aim of this study was to estimate the genetic and environmental parameters and crossbreeding effects on fatty acid and fat traits in the Iberian pig. Our final goal is to explore target selection traits and define crossbreeding strategies. The phenotypes were obtained under intensive management from 470 animals in a diallelic experiment involving Retinto, Torbiscal, and Entrepelado lines. The data set was composed of backfat thickness at the fourth rib (BFT), intramuscular fat (IMF) in the longissimus thoracis (LT), and the fatty acid profile for IMF and subcutaneous fat (SCF) traits. Data were analyzed through a Bayesian bivariate animal model by using a reparameterization of Dickerson's model. The results obtained showed an important genetic determinism for all traits analyzed with heritability ranging from 0.09 to 0.67. The common environment litter effect also had an important effect on IMF (0.34) and its fatty acid composition (0.06-0.53) at slaughter. The additive genetic correlation between BFT and IMF (additive genetic correlation [] = 0.31) suggested that it would be possible to improve lean growth independent of the IMF with an appropriate selection index. Furthermore, the high additive genetic correlation ( = 0.68) found between MUFA tissues would seem to indicate that either the LT or SCF could be used as the reference tissue for MUFA selection. The relevance of the crossbreeding parameters varied according to the traits analyzed. Backfat thickness at the fourth rib and the fatty acid profile of the IMF showed relevant differences between crosses, mostly due to line additive genetic effects associated with the Retinto line. On the contrary, those for IMF crosses were probably mainly attributable to heterosis effects. Particularly, heterosis effects were relevant for the Retinto and Entrepelado crosses (approximately 16% of the trait), which could be valuable for a crossbreeding system involving these lines.

Genetic evaluation for three-way crossbreeding.

BackgroundCommercial pig producers generally use a terminal crossbreeding system with three breeds. Many pig breeding organisations have started to use genomic selection for which genetic evaluation is often done by applying single-step methods for which the pedigree-based additive genetic relationship matrix is replaced by a combined relationship matrix based on both marker genotypes and pedigree. Genomic selection is implemented for purebreds, but it also offers opportunities for incorporating information from crossbreds and selecting for crossbred performance. However, models for genetic evaluation for the three-way crossbreeding system have not been developed.ResultsFour-variate models for three-way terminal crossbreeding are presented in which the first three variables contain the records for the three pure breeds and the fourth variable contains the records for the three-way crossbreds. For purebred animals, the models provide breeding values for both purebred and crossbred performances. Heterogeneity of genetic architecture between breeds and genotype by environment interactions are modelled through genetic correlations between these breeding values. Specification of the additive genetic relationships is essential for these models and can be defined either within populations or across populations. Based on these two types of additive genetic relationships, both pedigree-based, marker-based and combined relationships based on both pedigree and marker information are presented. All these models for three-way crossbreeding can be formulated using Kronecker matrix products and therefore fitted using Henderson’s mixed model equations and standard animal breeding software.ConclusionsModels for genetic evaluation in the three-way crossbreeding system are presented. They provide estimated breeding values for both purebred and crossbred performances, and can use pedigree-based or marker-based relationships, or combined relationships based on both pedigree and marker information. This provides a framework that allows information from three-way crossbred animals to be incorporated into a genetic evaluation system.

A crossbred reference population can improve the response to genomic selection for crossbred performance.

BackgroundBreeding goals in a crossbreeding system should be defined at the commercial crossbred level. However, selection is often performed to improve purebred performance. A genomic selection (GS) model that includes dominance effects can be used to select purebreds for crossbred performance. Optimization of the GS model raises the question of whether marker effects should be estimated from data on the pure lines or crossbreds. Therefore, the first objective of this study was to compare response to selection of crossbreds by simulating a two-way crossbreeding program with either a purebred or a crossbred training population. We assumed a trait of interest that was controlled by loci with additive and dominance effects. Animals were selected on estimated breeding values for crossbred performance. There was no genotype by environment interaction. Linkage phase and strength of linkage disequilibrium between quantitative trait loci (QTL) and single nucleotide polymorphisms (SNPs) can differ between breeds, which causes apparent effects of SNPs to be line-dependent. Thus, our second objective was to compare response to GS based on crossbred phenotypes when the line origin of alleles was taken into account or not in the estimation of breeding values.ResultsTraining on crossbred animals yielded a larger response to selection in crossbred offspring compared to training on both pure lines separately or on both pure lines combined into a single reference population. Response to selection in crossbreds was larger if both phenotypes and genotypes were collected on crossbreds than if phenotypes were only recorded on crossbreds and genotypes on their parents. If both parental lines were distantly related, tracing the line origin of alleles improved genomic prediction, whereas if both parental lines were closely related and the reference population was small, it was better to ignore the line origin of alleles.ConclusionsResponse to selection in crossbreeding programs can be increased by training on crossbred genotypes and phenotypes. Moreover, if the reference population is sufficiently large and both pure lines are not very closely related, tracing the line origin of alleles in crossbreds improves genomic prediction.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-015-0155-z) contains supplementary material, which is available to authorized users.

Contribution of semen trait selection, artificial insemination technique, and semen dose to the profitability of pig production systems: A simulation study

The economic impact of selection for semen traits on pig production systems and potential interaction with artificial insemination (AI) technique and semen dose remains partially understood. The objectives of this study were to compare the financial indicators (gross return, net profit, cost) in a three-tier pig production system under one of two selection strategies: a traditional strategy including nine paternal and maternal traits (S9) and an advanced strategy that adds four semen traits (S13). Maternal traits included the number of pigs born alive, litter birth weight, adjusted 21-day litter weight, and the number of pigs at 21 days, and paternal traits included days to 113.5 kg, back fat, average daily gain, feed efficiency, and carcass lean percentage. The four semen traits included volume, concentration, progressive motility of spermatozoa, and abnormal spermatozoa. Simultaneously, the impact of two AI techniques and a range of fresh refrigerated semen doses including cervical AI with 3 × 109 (CAI3) and 2 × 109 (CAI2) sperm cells/dose, and intrauterine AI with 1.5 × 109 (IUI1.5), 0.75 × 109 (IUI0.75), and 0.5 × 109 (IUI0.5) sperm cells/dose were evaluated. These factors were also evaluated using a range of farrowing rates (60%–90%), litter sizes (8–14 live-born pigs), and a selected semen collection frequency. The financial impact of the factors was assessed through simulation of a three-way crossbreeding system (maternal nucleus lines A and B and paternal nucleus line C) using ZPLAN. The highest return on investment (profit/cost) of boars was observed at 2.33 collections/wk (three periods of 24 hours between collections). Under this schedule, a significant (P < 0.0001) interaction between the selection strategy and the AI technique–dose combination was identified for the gross return; meanwhile, significant (P < 0.0001) additive effects of the selection strategy and AI technique–dose combination were observed for the net profit. The highest gross return was obtained under S13 with IUI0.75 and IUI0.5. The net profit of S13 was 34.37% higher than the traditional S9 (P < 0.0001). The net profit favored IUI0.5 with relative differences of 4.13%, 2.41%, 1.72%, and 0.43% compared to CAI3, CAI2, IUI1.5, and IUI0.75, respectively. The advanced selection strategy proposed including four semen traits is recommended on the basis of the higher profitability relative to the traditional strategy.

제주도 한우와 제주흑우실용화축군 집단에서 ADD1 유전자의 다형성이 경제형질에 미치는 영향

Genetic polymorphisms of adipocyte determination and differentiation factor 1 (ADD1) gene were screened in Hanwoo and Jeju Black cattle-derived commercial (JBC-DC) populations. The ADD1 genotypes were determined using the presence/absence of 84-bp fragment at intron 7 region. The association of ADD1 genotypes for economic traits was examined in both populations. In the Hanwoo steers, ADD1 D/carcasses showed significantly thicker backfat levels than those from WW (p<0.05). However, the thickest level of backfat appeared in WD heterozygotes, whereas thicker backfat did not appear in DD homozygotes in the JBC-DC population (p<0.05), leading to the supposition that synergic effects of alleles W and D increase backfat deposition. On the other hand, there was no association between the ADD1 genotypes and intramuscular fat deposition measured as meat qua lity index and marbling score. From these results, we concluded that the bovine ADD1 affected the backfat in subcutaneous tissue, rather than intramuscular fat in muscle tissue. In addition, the DD animals showed higher levels of meat color than those from W/- (p<0.05). Interestingly, a highly significant difference was found between the genotypes and carcass weight s only in the JBC-DC population, and D/- animals were heavier by more than 38 kg than those from WW (p<0.001). The results of this study reveal faster growth rate and differences in steer productivity according to genotypes of the ADD1 gene. These findings demonstrate that ADD1 genotypes may effectively function as molecular genetic markers for the improvement of Hanwoo and Jeju Black cattle-related crossbreeding systems.

Sustainable crossbreeding systems of beef cattle in the era of climate change

Beef cattle are unique, because they not only suffer from climate change, but they also contribute to climate change through the emission of greenhouse gases (GHG). Mitigation and adaptation strategies are therefore needed. An effective way to reduce the carbon footprint from beef cattle would be to reduce the numbers and increase the production per animal, thereby improving their productivity. Sustainable crossbreeding systems can be an effective way to reduce GHG, as it has been shown to increase production. There are a wide range of different cattle breeds in South Africa which can be optimally utilized for effective and sustainable crossbreeding. This paper reports on the effects of crossbreeding on the kilogram calf weaned per Large Stock Unit (kgC/LSU) for 29 genotypes. These genotypes were formed by crossing Afrikaner (A) cows with Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S) bulls and by back-crossing the F1 cows to the sire lines. A LSU is the equivalent of an ox of 450 kg with a daily weight gain of 500 g on grass pastures with a mean digestible energy (DE) content of 55% and a requirement of 75 MJ metabolizable energy (ME). Crossbreeding with A as dam line increased the kgC/LSU on average by 8 kg (+6%) - with the CA cross producing the most kgC/LSU (+8%) above that of the AA. The BA dam in crosses with C, H and S, increased kgC/LSU on average by 26 kg (+18%) above that of the AA dam, with the H x BA cross, producing the most kgC/LSU (+21%). The BA, CA, HA and SA F1 dam lines, back-crossed to the sire line breeds, increased kgC/LSU on average by 30 kg (21%), 21 kg (15%), 19kg (13%) and 26 kg (18%) above the that of the AA, respectively. The big differences between breeds in kgC/LSU provide the opportunity to facilitate effective crossbreeding that can be useful in the era of climate change. From this study it is clear that cow productivity can be increased by up to 21% through properly designed, sustainable crossbreeding systems, thereby reducing the carbon footprint of beef production.Keywords: Carbon footprint, cow productivity, kilogram calf, production systems

Crossbreeding to increase beef production: Additive and non-additive effects on fitness traits

Fitness is of paramount importance to efficient and profitable beef production. Thus, the objective of this study was to estimate genetic components of fitness traits measured in Afrikaner (A), Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S). For this study, the fitness traits recorded were percentage of cows exposed that were subsequently certified pregnant (PR), percentage of certified pregnant cows that subsequently calved (CR), percentage of calves born that survived to weaning (SV) and the percentage of cows exposed that ultimately weaned a calf (WR). Data were mean performance of straightbred, F1 cross, backcross and three-breed cross females. All crossbred females were of at least 25% A heritage. Breed group means were equated with their genetic expectations assuming recombination effects were nil and the heterosis effects were proportional to the expected heterozygosity in the crosses relative to the purebreds. With the exception of B-sired females from CA cross dams, the genetic model fit the breed group means with a high degree of fidelity. Breed-specific genetic effects tended not to individually exceed the magnitude of their standard errors. However, when the breed-specific genetic effects were combined to predict breed group means, the fitness of crossbred females, on average, exceeded that of their straightbred contemporaries. No particular advantage was noted for adding Brahman to the breed composition of crossbred females with at least 25% Afrikaner heritage. In summary, these data are viewed as being supportive of the use of breed resources in organized crossbreeding systems, such as two- and three-breed rotations that maintain at least 25% Afrikaner germplasm in the breeding females. Keywords : Afrikaner cattle genotypes, heterosis effects, predicted phenotypic values, weaning rate