Genetic Merit Research Articles

Comparative study of pure RCC and graded RCC cattle through software based recording system in different regions of Bangladesh

Recording systems are important to maintain data properly with a view to justifying the merits of productive and reproductive parameter as well as pedigree evaluation, towards any decision making pathway. Considering this, the current research was conducted to assess the computer and mobile software based animal recording system, which have important effect on production and reproduction on Red Chittagong cattle and their graded cattle. For this reason, this survey was conducted at well-developed pre-tested questionnaire through mobile application software under thirteen study areas. The study areas were selected based on the density of Red Chittagong Cattle population in those areas. After data collectionollected data were analyzed using SPSS 22.0 software and mean comparisons were estimated by LSD and Duncan method. Numbering (highest-11.32% at Godagari, lowest at Naikhongchari-4.25%), Artificial Insemination (highest 20% at Godagari and lowest at Naikhongchari-1%), service per conception rate (highest at Sylhet-1.37 and lowest at Swandip-1.14), calving rate (highest 12.34% at Anowara and lowest 4.20% at Keshobpur) and birth weight (highest 16.50±0.57 kg at Hathazari and lowest 12.79±0.49 kg at Godagari) were different in each regions. Lactation length, milk yield, and growth rate of two category cattle were found statistically significant (P<0.05) between two groups of cattle. These three productive parameters were higher for Red Chittagong Cattle (230±5.16 days, 3.10±0.13 L/day, 0.197 kg/day) respectively. The software based recording system helps to get proper data which will help for selection of superior sires and dams with high genetic merit as well as data can be restored anytime from this software based recording system. Asian Australas. J. Biosci. Biotechnol. 2023, 8(3), 70-77

Combined purebred and crossbred genetic evaluation of Columbia, Suffolk, and crossbred lamb birth and weaning weights: systematic effects and heterogeneous variances.

Despite the benefits of crossbreeding on animal performance, genetic evaluation of sheep in the U.S. does not directly incorporate records from crossbred lambs. Crossbred animals may be raised in different environments as compared to purebreds. Systemic factors such as age of dam and birth and rearing type may, therefore, affect purebred and crossbred performance differently. Furthermore, crossbred performance may benefit from heterozygosity, and genetic and environmental variances may be heterogeneous in different breeds and their crosses. Such issues must be accounted for in a combined (purebred and crossbred) genetic evaluation. The objectives of this study were to i) determine the effect of dam age and birth type on birth weight, and dam age and birth-rearing type on weaning weight, in purebred and crossbred lambs, ii) test for heterogeneous genetic and environmental variances in those weights, and iii) assess the impact of including weights on crossbred progeny on sire estimated breeding values (EBV). Performance records were available on purebred Columbia and Suffolk lambs. Crossbred information was available on lambs sired by Suffolk, Columbia or Texel rams mated to Columbia, Suffolk, or crossbred ewes. A multiple-trait animal model was fitted in which weights from Columbia, Suffolk, or crossbred lambs were considered different traits. At birth, there were 4,160, 2,356, and 5,273 Columbia, Suffolk, and crossbred records, respectively, with means (SD) of 5.14 (1.04), 5.32 (1.14), and 5.43 (1.23) kg, respectively. At weaning, on average at 122 (12) d, there were 2,557, 980, and 3,876 Columbia, Suffolk, and crossbred records, respectively, with corresponding means of 39.8 (7.2), 40.3 (7.9), and 39.6 (8.0) kg. Dam age had a large positive effect on birth and weaning weight in pure and crossbred lambs. At birth, however, the predicted effect was larger in crossbred and Suffolk lambs. While an increase in a number of lambs born and reared had a strong and negative influence on birth and weaning weight, the size of the effect did not differ across-breed types. Environmental variances were similar at birth and weaning, but additive variances differed among breed types for both weights. Combining purebred and crossbred information in the evaluation not only improved predictions of genetic merit in purebred sires but also allowed for direct comparisons of sires of different breeds. Breeders thus can benefit from an additional tool for making selection decisions.

101 Selecting bovine embryos using genomics tools: sex determination and genetic merit assessment in developing cattle embryos

101 Selecting bovine embryos using genomics tools: sex determination and genetic merit assessment in developing cattle embryos

Rice (Oryza sativa L.) Grain Size, Shape, and Weight-Related QTLs Identified Using GWAS with Multiple GAPIT Models and High-Density SNP Chip DNA Markers

This study investigated novel quantitative traits loci (QTLs) associated with the control of grain shape and size as well as grain weight in rice. We employed a joint-strategy multiple GAPIT (Genome Association and Prediction Integrated Tool) models [(Bayesian-information and Linkage-disequilibrium Iteratively Nested Keyway (BLINK)), Fixed and random model Circulating Probability Uniform (FarmCPU), Settlement of MLM Under Progressive Exclusive Relationship (SUPER), and General Linear Model (GLM)]–High-Density SNP Chip DNA Markers (60,461) to conduct a Genome-Wide Association Study (GWAS). GWAS was performed using genotype and grain-related phenotypes of 143 recombinant inbred lines (RILs). Data show that parental lines (Ilpum and Tung Tin Wan Hein 1, TTWH1, Oryza sativa L., ssp. japonica and indica, respectively) exhibited divergent phenotypes for all analyzed grain traits), which was reflected in their derived population. GWAS results revealed the association between seven SNP Chip makers and QTLs for grain length, co-detected by all GAPIT models on chromosomes (Chr) 1–3, 5, 7, and 11, were qGL1-1BFSG (AX-95918134, Chr1: 3,820,526 bp) explains 65.2–72.5% of the phenotypic variance explained (PVE). In addition, qGW1-1BFSG (AX-273945773, Chr1: 5,623,288 bp) for grain width explains 15.5–18.9% of PVE. Furthermore, BLINK or FarmCPU identified three QTLs for grain thickness independently, and explain 74.9% (qGT1Blink, AX-279261704, Chr1: 18,023,142 bp) and 54.9% (qGT2-1Farm, AX-154787777, Chr2: 2,118,477 bp) of the observed PVE. For the grain length-to-width ratio (LWR), the qLWR2BFSG (AX-274833045, Chr2: 10,000,097 bp) explains nearly 15.2–32% of the observed PVE. Likewise, the major QTL for thousand-grain weight (TGW) was detected on Chr6 (qTGW6BFSG, AX-115737727, 28,484,619 bp) and explains 32.8–54% of PVE. The qTGW6BFSG QTL coincides with qGW6-1Blink for grain width and explained 32.8–54% of PVE. Putative candidate genes pooled from major QTLs for each grain trait have interesting annotated functions that require functional studies to elucidate their function in the control of grain size, shape, or weight in rice. Genome selection analysis proposed makers useful for downstream marker-assisted selection based on genetic merit of RILs.

Moving towards a rolling front strategy for VERACEL's advanced-generation eucalypt hybrid breeding program

The eucalyptus breeding program at VERACEL started in the mid-1990s driven by the objective of producing outstanding clones adapted to the Bahia South (Brazil) environment, and thus creating highly productive stands with high quality pulpwood. The breeding population initially comprised several introduced pure species collections (mainly E. grandis and E. urophylla) from Australian provenances and ex-Brazilian hybrids (mostly E. urophylla × E. grandis). These populations were first structured according to a typical reciprocal recurrent selection scheme to identify outstanding urograndis F1 hybrids. In the early 2000s, the program developed and tested several second-generation F1 hybrids, in addition to some progeny and clonal trials with a few introduced new species and hybrids. More recently, starting in 2016, a new set of F2 progeny and clonal hybrid trials were established from previously selected F1 parents. This second generation of hybrids was complemented with other 2-way and 3-way hybrid crosses to form an advanced generation synthetic population. To manage such breeding population, including pure species, F1 and advanced F2 hybrids, and backcross hybrids, VERACEL is restructuring its breeding program to implement a more flexible multispecies rolling front selection and mating scheme. This would allow the strategy to effectively combine all available phenotypic and pedigree information. Currently, the database, spanning three generations of breeding, includes 105 progeny and clonal trials, over 2,300 individual clones, and more than 30,000 pure and hybrid seedling progenies. We expect that the breeding and selection strategy will ensure optimum long-term progress in the additive genetic merit of selected parents, as well as exploit the hybrid heterosis and non-additive genetic effects to identify outstanding clones in the short term. Our study describes in some detail the current state-of-the-art of VERACEL’s breeding and clonal populations, and discusses key elements of this strategy. We discuss the challenges posed by the increasing relevance of good adaptations to climate change and diseases, and the complex genetics of inter-specific hybridization, especially as the program enters its 3rd generation of testing and selections.

Differences in the choice of beef artificial insemination sires used by dairy producers versus beef producers

The growing demand among dairy producers for suitable beef sires to mate to their females creates the possibility of separate breeding programs to generate beef sires for the dairy sector versus those for the beef sector. Informing such a decision is the extent of the genetic differences among beef sires used by dairy producers relative to those used by beef producers. The objective therefore of the present study was to use a large national database of artificial insemination (AI) records in dairy and beef cow herds to establish the difference in mean genetic merit of beef AI sires used by dairy producers versus those used by cow-calf beef producers. The traits explored were gestation length, calving difficulty, and perinatal mortality as well as the 3 carcass traits of carcass weight, conformation, and fat score. Carcass conformation and fat score are mechanically assessed on a scale of 1 (poor conformation and low fat cover) to 15 (excellent conformation and high fat cover). Sire genetic merit differences for feed intake and docility were also examined. Estimates of genetic merit for all 8 traits on individual AI sires available at the time of service were used. A total of 1,230,622 AI records comprised 909,719 services from dairy herds and 320,903 services from beef herds were used. Of the 1,802 beef AI sires represented in the entire dataset, over half were used by both dairy and beef herds representing ≥98% of the services in each production system. However, the usage rate of individual AI sires differed between dairy and beef herds with the Spearman rank correlation between the quantity of inseminations per sire in dairy and beef herds being just 0.38. This correlation means that beef AI sires used heavily in the beef herd were not always those heavily used in dairy herds. A clear difference in the mean genetic merit of beef AI sires selected by dairy producers relative to those selected by beef cow-calf producers was obvious with the extent of the difference being a function of whether the female served was a nulliparous heifer or a cow. Much of the differences in genetic merit of chosen beef AI sires between dairy and beef producers was actually attributable to differences in breed choice, albeit some within-breed selection was also evident. Irrespective, dairy producers, on average, chose shorter gestation length sires whose progeny were genetically less predisposed to require intervention during the birthing process; these sires had genetic merit estimates expected to result in lighter and less conformed progeny carcasses relative to the beef AI sires used by beef producers. Results point to large differences in genetic merit of the beef AI sires chosen by dairy versus beef producers, much of which actually reflected differences in breed choice among dairy and beef producers.

Elucidation of the genetic determination of clutch traits in Chinese local chickens of the Laiwu Black breed

BackgroundEgg laying rate (LR) is associated with a clutch, which is defined as consecutive days of oviposition. The clutch trait can be used as a selection indicator to improve egg production in poultry breeding. However, little is known about the genetic basis of clutch traits. In this study, our aim was to estimate genetic parameters and identify quantitative trait single nucleotide polymorphisms for clutch traits in 399 purebred Laiwu Black chickens (a native Chinese breed) using a genome-wide association study (GWAS).MethodsIn this work, after estimating the genetic parameters of age at first egg, body weight at first egg, LR, longest clutch until 52 week of age, first week when the longest clutch starts, last week when the longest clutch ends, number of clutches, and longest number of days without egg-laying until 52 week of age, we identified single nucleotide polymorphisms (SNPs) and potential candidate genes associated with clutch traits in Laiwu Black chickens. The restricted maximum likelihood method was used to estimate genetic parameters of clutch pattern in 399 Laiwu Black hens, using the GCTA software.ResultsThe results showed that SNP-based heritability estimates of clutch traits ranged from 0.06 to 0.59. Genotyping data were obtained from whole genome re-sequencing data. After quality control, a total of 10,810,544 SNPs remained to be analyzed. The GWAS revealed that 421 significant SNPs responsible for clutch traits were scattered on chicken chromosomes 1–14, 17–19, 21–25, 28 and Z. Among the annotated genes, NELL2, SMYD9, SPTLC2, SMYD3 and PLCL1 were the most promising candidates for clutch traits in Laiwu Black chickens.ConclusionThe findings of this research provide critical insight into the genetic basis of clutch traits. These results contribute to the identification of candidate genes and variants. Genes and SNPs potentially provide new avenues for further research and would help to establish a framework for new methods of genomic prediction, and increase the accuracy of estimated genetic merit for egg production and clutch traits.

Identification of quantitative trait loci and associated candidate genes for pregnancy success in Angus–Brahman crossbred heifers

BackgroundIn beef cattle, more than 50% of the energy input to produce a unit of beef is consumed by the female that produced the calf. Development of genomic tools to identify females with high genetic merit for reproductive function could increase the profitability and sustainability of beef production.ResultsGenome-wide association studies (GWAS) were performed using a single-step genomic best linear unbiased prediction approach on pregnancy outcome traits from a population of Angus–Brahman crossbred heifers. Furthermore, a validation GWAS was performed using data from another farm. Heifers were genotyped with the Bovine GGP F250 array that contains 221,077 SNPs. In the discovery population, heifers were bred in winter breeding seasons involving a single round of timed artificial insemination (AI) followed by natural mating for 3 months. Two phenotypes were analyzed: pregnancy outcome to first-service AI (PAI; n = 1,481) and pregnancy status at the end of the breeding season (PEBS; n = 1,725). The heritability was estimated as 0.149 and 0.122 for PAI and PEBS, respectively. In the PAI model, one quantitative trait locus (QTL), located between 52.3 and 52.5 Mb on BTA7, explained about 3% of the genetic variation, in a region containing a cluster of γ-protocadherin genes and SLC25A2. Other QTLs explaining between 0.5% and 1% of the genetic variation were found on BTA12 and 25. In the PEBS model, a large QTL on BTA7 was synonymous with the QTL for PAI, with minor QTLs located on BTA5, 9, 10, 11, 19, and 20. The validation population for pregnancy status at the end of the breeding season were Angus–Brahman crossbred heifers bred by natural mating. In concordance with the discovery population, the large QTL on BTA7 and QTLs on BTA10 and 12 were identified.ConclusionsIn summary, QTLs and candidate SNPs identified were associated with pregnancy outcomes in beef heifers, including a large QTL associated with a group of protocadherin genes. Confirmation of these associations with larger populations could lead to the development of genomic predictions of reproductive function in beef cattle. Moreover, additional research is warranted to study the function of candidate genes associated with QTLs.

148 Does Increased Gametic Variance Translate to Increased Heterogeneity in progeny?

Abstract The expected genetic merit of a new-born calf is simply the average genetic merit estimates of its parents. Parents with a very heterogenous genotype could, however, potentially generate a more heterogenous group of progeny than parents with a more homogenous genotype. The objective of the present study was to test this hypothesis, and a secondary objective was to determine the expected progeny variability in their estimates of genetic merit for traits associated with dairy-beef production based on their expected genomic heterogeneity. Gametic variance for calving difficulty, calf mortality, gestation length, docility, feed intake, and carcass weight, fat, and conformation was estimated for 22,038 beef sires of multiple breeds. Sire gametic variance per trait was estimated for each chromosome from all heterozygous single nucleotide polymorphisms (SNP), their location within the genome, and the estimated effect of each SNP on each trait. Gametic variance was estimated for the whole genome as the sum of the estimated gametic variance of all chromosomes. Individual progeny phenotypic records for each trait were adjusted for animal sex, dam parity and dam genetic merit for the trait, heterosis, recombination loss, and contemporary group. The correlations between sire estimated gametic variance and the standard deviation of his (adjusted) progeny phenotypes were then estimated for all sires with at least 20 progeny records; the number of genotyped sires with at least 20 progeny ranged from 2,395 (heifer calving assistance) to 8,545 (calf mortality). The mean gametic variance, relative to the variance of sire genetic merit, for heifer calving difficulty, cow calving difficulty, calf mortality, gestation length, docility, feed intake, carcass weight, carcass conformation, carcass fat were 0.0002, 0.0005, 0.09, 0.07, 0.30, 0.02, 0.25, 0.05, and 0.12, respectively. With the exception of carcass fat and carcass weight, the correlations between the estimated gametic variance per sire and the standard deviation of his (adjusted) progeny phenotypes were non-existent (-0.06 to 0.04); the correlations between the standard deviation of the adjusted progeny phenotypes and the gametic variance for carcass fat and carcass weight were 0.29 and 0.16, respectively. The (weak) correlations between gametic variance and progeny phenotypes for carcass fat and carcass weight suggest that greater gametic variance is associated with increased progeny heterogeneity for both carcass traits. Nevertheless, accounting for gametic variance when selecting beef bulls for use on dairy females seems to provide little benefit.

PSXIV-4 Body Condition and Production Status Impacts on Estrus Indicators in Beef Cattle on a Producer Farm

Abstract The use of artificial insemination (AI) in cattle can increase farm profitability by increasing the genetic merit of offspring, but animal body condition (fatness) and stage of production can influence breeding efficacy. Therefore, during an on-farm AI session, the effect of body condition score and production status (nursing offspring or not) on indicators of estrus (readiness for breeding) was examined. Thirty-six cows 3 to 12 years of age and having previously had at least one calf were used. Cows were estrus synchronized by the owners using the Co-Synch with CIDR fixed time AI protocol (GnRH and CIDR on day 0 followed by CIDR removal and prostaglandin on day 7 with AI and GnRH on day 10). At AI using cryopreserved semen from a commercial source (Premier Select Sires), body condition score was assessed (1-9; 1 = emaciated, 9 = obese), and indicators of estrus (presence of mucous, pink color of vulva, turgid and open cervix and easy insemination) were noted. On this farm, body condition scores for the animals the producer chose to estrus synchronize ranged from 3 to 5. Animals were nursing calves 3 to 5 months of age (n = 15) or were not nursing calves (n = 21). Statistical analysis (with SAS) indicated that nursing negatively impacted body condition as well as number of estrus indicators noted at AI and that body condition tended to be positively related to the number of estrus indicators noted.

189 Single-Step Gblup Evaluation for Behavioral Traits in Labrador Retrievers Used as Guide Dogs

Abstract The objective of this study was to evaluate the accuracy of prediction in a genomic selection program for behavior traits in a population of Labrador Retrievers used as service dogs. Phenotypic data were collected in 4841 Labrador Retrievers with ages ranging from 3 months to 2.5 years, for 17 phenotypes from the International Working Dog Registry behavior checklist. The behavior checklist is a document that standardizes a scoring system for the reaction of an individual dog to environmental stimulus. Such scores are used to assess behavior and suitability of a dog for training. Pedigree contained 23,593 animals with birth dates ranging from 1991 to 2019. Genomic data were available for 457 individuals and obtained by low-pass whole genome sequences and reduced to a 250K SNP chip. Breeding values were calculated using a single trait animal model that included the fixed effects of sex, year of birth, and a contemporary group that included month/year of behavior test and organization that hosted the test. Variance components were estimated using AIREML. Genomic information was included in the model under a single-step GBLUP (ssGBLUP) approach by substituting the pedigree numerator relationship matrix with a matrix that combined pedigree and genomic relationships. Additionally, the genomic relationship matrix was modified under a weighted ssGBLUP (wssGBLUP) approach that allowed SNPs to have different distributions. Accuracies were evaluated in a 5-fold cross-validation that simulated a forward-in-time prediction. Heritabilities were low to moderate on all traits and varied from 0.025 to 0.37. Prediction based solely on pedigree information averaged 0.49 and ranged from 0.34 to 0.69. ssGBLUP increased the average accuracy to 0.55 and ranged from 0.34 to 0.72. Genomic estimated breeding values were more accurate than those computed with pedigrees for most traits. Gains in accuracy were limited by the small number of genotyped animals and are expected to increase as more animals are genotyped. The differences seen between the ssGBLUP approach and the wssGBLUP were minimal, and accuracies decreased after the second iteration. Those results indicate that behavior traits in this population are likely highly polygenic and would not benefit from weighted approaches. However, interpretation may change, as the limitations of the current study are due to the small number of genotyped individuals. Better SNP weight estimates may occur with more animals enrolled in the program, and with that a better description of the genetic architecture of the traits. The gains in accuracy show that genomic selection can help with improvement by identifying which young dogs have the highest genetic merit for the desired traits and are the best choices to keep as replacement breeders. The use of ssGBLUP is adequate for this canine data where not all animals are genotyped, and its use is recommended in selection programs focused on service dogs.

121 Quantifying Genetic Relationships to Maintain Genetic Diversity in the Canadian Dairy Population

Abstract Intensive selection pressure coupled with the use of a limited number of high genetic merit sires has resulted in reduced effective population size and increased levels of inbreeding in dairy cattle populations. The increased rate of inbreeding amplifies the frequency of recessive deleterious alleles, possibly leading to inbreeding depression in economically important traits, such as disease resistance, fertility and production. To better understand the relationship of available and active breeding sires to Canadian herds, quantifying genetic relationships between these groups could prove insightful. The genetic relationship value (R-value) represents the average number of alleles identical by descent shared between an animal and a reference population and is currently estimated based on pedigree information. Furthermore, the average R-value indicates the relationship of a sire to the rest of the population. Estimating the R-value between sires and individual herds may offer a more refined tool for producers to select sires that are less related to their specific herds. The aim of this study was to quantify and characterize R-values between individual sires and individual herds within the Canadian Holstein population. To quantify R-values, a dataset comprised of 11,914 sires born between 1953 and 2020 and 584,740 active cows born between 1997 and 2022 from 5,592 herds was considered. Active cows were defined as those currently alive, on milk recording, and actively contributing to the national milk inventory. Active sires were considered those used to breed the active cows. All data were provided by Lactanet Canada and analyses were carried out on PEDIG using the par2 program for relationship estimation. Results indicate that herd-level R-values (i.e., R-values estimated using individual sires and individual herds) showed variation. The R-value of individual sires to individual herds containing active cows ranged from 0.43% to 32.38. This result indicates that outbred sires are available to individual farmers when the population is considered at the herd level, and that the development of herd-level R-values may provide a selection tool which promotes the use of less related sires. Next steps include developing and estimating genomic R-values and comparing them with the pedigree-based R-values for the genotyped Canadian Holstein population. By better understanding of the relationship of available breeding sires to individual Canadian herds, a simple tool for producers to identify sires which are less related to their herds can be developed.

312 Emissions Intensity of Growing Cattle with Contrasting Residual Methane Production, Average Daily Gain, Feed Conversion Ratio, Residual Feed Intake, and Feed Intake

Abstract Various options exist to produce beef from growing cattle with low environmental footprint normally linked to the genetic merit of animals for traits such as residual feed intake (RFI), residual methane production (RMP), residual CO2e production (RCeP), average daily gain (ADG), feed conversion ratio (FCR), and dry matter intake (DMI; % of BW). The ultimate environmental footprint can be measured through the intensity of methane emissions (IME) in g CH4/kg ADG or the intensity of CO2e (ICDE) adding up both CH4 and CO2 production in g CO2e/kg ADG. The objective of the present study was to compare the IME and ICDE of animals with low, medium, and high traits for RMP, RCDE, ADG, FCR, RFI, and DMI. Five cohorts of 77 steers composite steers and heifers (Angus, Charolais, and Shorthorn) were tested for RFI for 70 d using electronic feeders and CH4 and CO2 production measured using two GreenFeed units in the pens. Only animals with more than 25 visits longer than 3 min were used for the analysis and the final dataset contained 202 animals. Animals within each RFI test were divided into equal groups with low, medium, and high values for each variable RFI, RMP, ADG, FCR, and DMI. Data were averaged for each animal and trial, and analyzed using ANOVA with the fixed effects of group, trial, and their interaction. The IME were different for animals with contrasting RMP, ADG, and FCR (P < 0.05) but not between animals with contrasting DMI and RFI (P > 0.05). The largest difference on IME was found between animals with low and high RMP, ADG, and FCR, and least for RFI and DMI with values being 33.9, 28.1, 22.3, 6.2, and 1.5 g CH4/kg ADG, respectively (Table 1). Results were similar when emissions intensity were expressed as ICDE (Table 1), except animals with low RFI produced less ICDE compared with those with high FI (P = 0.02). Results indicate that the environmental footprint of growing cattle can be reduced with animals with low RMP and high ADG at similar extents, whereas RFI and DMI have lesser impact.

Molecular and phenotypic profiling of white Guinea yam (Dioscorea rotundata) breeding lines

Phenotypic and genotypic profiling helps identify genotypes with suitable and complementary traits for genetic improvement in crops. A total of 32 traits were assessed in 36 genotypes of white Guinea yam established in a 6 × 6 triple lattice design. The objective was to evaluate an array of plant traits that define the genetic merits of breeding lines for yam improvement. Different analytical tools were used to identify and prioritize relevant traits defining the genetic merits of breeding lines in the yam improvement program. Out of the 32 traits measured, the linear combination of 14 traits that minimize within-group variance and maximize between-group variance for discriminating the genetic values of yam breeding lines were identified. When best linear unbiased prediction with genomic relationship matrix (GBLUP) was used, the accuracies of genomic breeding values were higher (r=0.87 to 0.97) for the seven traits (dry matter content, intensity of flesh oxidization of shredded tuber, pasting temperature, pasting time, tuber flesh colour, yam mosaic virus and fresh tuber yield) with high broad-sense heritability values (H2m>0.6). While, for the remaining seven traits with low (H2m<0.3) to medium (H2m=0.3 to 0.54) broad-sense heritability values, the accuracies of genomic estimated breeding values (GEBV) were low (r<0.4) to medium (r=0.4-0.8). The genotype–trait (GT) biplot display revealed superior clones with desirable genetic values for the key traits. These results are relevant for parental selection aimed at improving key agronomic traits in white Guinea yam.

104 Investigation Into the Serum Metabolome and Identification of Biomarkers for Early Detection of Postpartum Dysgalactia Syndrome in Sows

Abstract The swine industry is comprised of highly productive and healthy sows capable of weaning large litters for multiple parities. This prolificacy has resulted in greater metabolic demands during lactation due to increased capacity and demand for milk production. Modern sows also have increased genetic merit for leanness which has altered the amount of energy reserves available for mobilization to support the growing demands of lactation. Together, these factors may render modern sows more vulnerable to metabolic disorders such as postpartum dysgalactia syndrome (PDS) or mastitis-metritis-agalactia (MMA). Described as a metabolic and hormonal disturbance, a hallmark of PDS is a reduction (dysgalactia) or cessation (agalactia) in milk production after farrowing. Insufficient milk production by the sow leads to increased piglet mortality, causing substantial economic losses, reducing sow welfare, and resulting in premature removal of sows from the herd. Our prior reports have shown differences in circulating analytes and inflammatory markers between healthy sows and sows affected with PDS following parturition. However, very few differences were observed before clinical signs were evident, rendering these analytes ineffective in early detection of PDS. Therefore, the objective of the current study was to utilize gas-chromatography mass-spectrometry (GC-MS) to further characterize the biological conditions and metabolic pathways contributing to PDS in sows. Through this, we aimed to identify small molecules in circulation with the potential for use as a biomarker to aid in early detection of PDS. To accomplish this, a study was conducted on a commercial sow farm with a history of poor lactation performance. Sows (n = 36) with clinical signs of PDS were matched by parity and day of lactation with healthy control (CON) sows (n = 36) that remained unaffected. Blood samples collected at farrowing (timepoint 1) and at onset of clinical PDS (timepoint 2) were subjected to GC-MS. As expected, piglets from PDS sows had decreased (P < 0.01) average daily gain and greater mortality than piglets from control sows. Following GC-MS analysis, 16 and 41 molecules were identified as significantly different between CON and PDS sows at timepoint 1 and timepoint 2, respectively (P < 0.10). A difference in 2-hydroxybutyric acid, an early marker for insulin resistance and impaired glucose regulation, was observed at timepoint 1. Additional molecules identified as significantly different at timepoint 1 include D-pinitol, D-glucose, inositol (3,6)-bisphosphate, and others. These differentially abundant molecules at timepoint 1 represent potential biomarkers for early detection of PDS.

Genome-wide association study for growth traits in Blanco Orejinegro and Romosinuano cattle

Growth traits are economically important characteristics for the genetic improvement of local cattle breeds. Genome-wide association studies (GWAS) provide valuable information to enhance the understanding on the genetics of complex traits. The aim of this study was to perform a GWAS to identify genomic regions and genes associated to birth weight, weaning weight adjusted for 240 days, 16 months, and 24 months weight in Romosinuano (ROMO) and Blanco Orejinegro (BON) cattle. A single-step genomic-BLUP was implemented using 596 BON and 569 ROMO individuals that were genotyped with an Illumina BovineSNP50 BeadChip. There were 25 regions of interest identified on different chromosomes, with few of them simultaneously associated with two or more growth traits and some were common to both breeds. The gene mapping allowed to find 173 annotations on these regions, from which 49 represent potential candidate genes with known growth-related functions in cattle and other species. Among the regions that were associated with several growth traits, that at 24 – 27 MB of BTA14, has important candidate genes such as LYPLA1, XKR4, TMEM68 and PLAG1. Another region of interest at 0.40–0.77 Mb of BTA23 was identified in both breeds, containing KHDRBS2 as a potential candidate gene influencing body weight. Future studies targeting these regions could provide more knowledge to uncover the genetic architecture underlying growth traits in BON and ROMO cattle. The genomic regions and genes identified in this study could be used to improve the prediction of genetic merit for growth traits in these creole cattle breeds.

The variation in the beta-casein genotypes and its effect on milk yield and genomic values in Holstein-Friesian cows

The A2 milk marker is gaining popularity worldwide; thus, many farms plan to convert their dairy cattle herds to the A2A2 genotype. Variation in beta-casein genotypes needs to be monitored in large dairy cattle populations. Therefore we aimed to evaluate the genotypic distributions, population genetics, and diversity parameters in Holstein-Friesian cows. A total of 1200 cattle were genotyped using the Affymetrix® Axiom® array system. We performed an association analysis regarding the CSN2 genotypes and phenotypic traits, including lactation and test-day milk yield. We next evaluated the effects of the genotypes considering the genetic merit of the animals. Animals were grouped based on their PTAs for milk production, fat, protein, and daughter pregnancy rate. Thus, we tested the genotype × genetic merit interaction for significance. The A2 allele frequency is remarkably high (0.68), and the heterozygous genotype is predominant (46.25%). The marker showed intermediate variability and diversity levels, indicating a considerable frequency of the A1A1 genotype (9.33%) remains in the population. ANOVA results showed no significant association between the CSN2 genotypes and milk yield traits. A similar finding is valid for the genotype × genetic merit regarding the genomic test results. The data presented here may be helpful for further investigations and applications on A2 milk production.

High genetic merit dairy heifers grazing low quality forage had similar weight gain and urinary nitrogen excretion to those of low genetic merit heifers.

Climate variability and increasing drought events have become significant concerns in recent years. However, there is limited published research on body weight (BW) change of dairy heifers with different genetic merit when grazing on drought impacted pastures in southern Australia. Achieving target body weight (BW) is vital for dairy heifers, especially during critical stages like mating and calving. This study aimed to assess dry matter (DM) intake, BW change, urinary nitrogen excretion, and grazing behaviours of high vs. low genetic dairy heifers grazing pasture during a 43-day experimental period in a drought season. Forty-eight Holstein Friesian heifers grazed on ryegrass-dominant pasture and were divided into two groups based on their high and low Balanced Performance Index (HBPI and LBPI, respectively). Each group was further stratified into six plots, with similar BW, resulting in four heifers per replication group. Data from the five measurement days were averaged for individual cows to analyse the dry matter intake, nitrogen intake and nitrogen excretion. The statistical model included the treatment effect of BPI (H and L) and means were analysed using ANOVA. The pasture quality was poor, with metabolizable energy 9.3 MJ/Kg DM and crude protein 5.9% on a DM basis. Nitrogen intake and urinary nitrogen excretion were significantly higher (p < 0.05) in HBPI compared to the LBPI. However, despite these differences, the study did not find any advantages of having HBPI heifer grazing on low quality forage in terms of BW performance.

Genetic associations between stayability to consecutive calvings and traits of economic interest in taurine and zebu breeds.

Stayability (STAY) is a way to evaluate the productive longevity of females. Measuring the STAY at each cow calving allows earlier indicators of longevity to be obtained. Our objective with this study was to verify the association between STAY and consecutive calvings and traits potentially used as selection criteria in beef cattle, such as age at first calving (AFC), days to calving (DC), weaning weight (WW), and yearling weight (YW). Data from the Nelore, Angus/Brangus, and Hereford/Braford breeds were used. The estimation of variance components and subsequent prediction of breeding values were performed for all traits. The estimated breeding values (EBV) were used to analyse the association between STAY and the other traits. The Pearson's correlation estimated between the EBV for the intercept coefficient for STAY to consecutive calvings and those of AFC, DC, WW (direct and maternal effects), and YW was favourable and of low magnitude (<0.25) depending on the breed studied. The influence of the genetic merit of AFC on the chance of selection for STAY was favourable and relevant regardless of the intensity of selection and breed. DC and WW (maternal effect) traits were favourably influenced by the chance of selection for STAY, irrespective of breed. The WW (direct effect) did not affect the chance of selection for STAY for the Nelore and Hereford/Braford breeds and negatively influenced, but to a small extent, the Angus/Brangus breed. For YW, an increase in genetic merit affected the chances of selection for STAY, depending on the breed and selection intensity evaluated. The influence of the genetic merit for AFC, DC, and WW (maternal effect) on the chance of selection for STAY to consecutive calvings was favourable and relevant regardless of the selection intensity scenario evaluated. The WW (direct effect) did not influence the chance of selection for STAY. For the scenario with high selection intensity, the selection for YW favourably influenced the chance of selection for STAY in Angus/Brangus and Hereford/Braford breeds but not in Nelore.

Os embriões bovinos podem ser transferidos com sucesso após 40 anos de criopreservação?

ABSTRACT Global advances in reproductive biotechnology have allowed for the transfer of embryos from donor females with high genetic merit to recipients using the cryopreservation technique, which preserves an embryo of excellent quality and viability, thereby achieving a feasible pregnancy rate. The objective of this study was to evaluate the quality and viability of Holstein embryos that have been cryopreserved for more than 40 years under glycerol freezing. The embryos were transferred to the recipient heifers using a non-surgical method. Two 17-month-old Holstein heifers (360 kg live weights) which were clinically healthy and reproductively active were used as the recipients. Two bovine embryos of Grade 1 quality were thawed and evaluated for their morphology. Of the two embryo transfers, one pregnancy was achieved, resulting in the birth of a calf. Therefore, embryos frozen in liquid nitrogen and glycerol as a cryopreservative for more than 40 years maintained their quality and viability to produce a live calf.