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McFarland ED, Elsohaby I, Baes CF, Stryhn H, Keefe G, McClure JT. Impacts of preweaning colostrum feeding practices and health measures on dairy cow production, while accounting for genetic potential. J Anim Sci 2024; 102:skae061. [PMID: 38459921 PMCID: PMC10998465 DOI: 10.1093/jas/skae061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 03/08/2024] [Indexed: 03/11/2024] Open
Abstract
Calf management and health are essential for setting up the foundation of a productive cow. The objectives of this study were to estimate the impact of preweaning practices on milk production parameters while accounting for an animal's genetic potential in New Brunswick, Canada. A retrospective cohort study was performed on 220 heifer calves from eight herds born in 2014-2015. Preweaning practices and health data were recorded by producers and reviewed by the herd veterinarian for each calf. The herd veterinarian also visited the farms to collect serum samples from calves and frozen colostrum samples. The production outcomes assessed were milk, protein and fat yields, standardized to 305 d for the first lactation (L1) and a combined group of lactations two and three (L2 + 3). The genomic potential was determined as genomic parent averages (GPA) for the associated production parameters. Analysis was performed with multivariable linear (L1) and linear mixed (L2 + 3) regression models. In L1, for every 1.0 kg increase in weaning weight, milk, protein, and fat yield increased by 25.5, 0.82, and 1.01 kg, respectively (P < 0.006). Colostrum feeding time (CFT) positively impacted L1 milk and protein production, with feeding between 1-2 h of life producing the greatest estimates of 626 kg of milk and 18.2 kg of protein yield (P < 0.007), compared to earlier or later CFT. Fat yield production was decreased by 80.5 kg (P < 0.006) in L1 when evaluating animals that developed a preweaning disease and were not treated with antibiotics compared to healthy untreated animals. Impacts on L2 + 3 were similar across all production outcomes, with a positive interaction effect of CFT and weaning weight. Compared to CFT < 1 h, the later CFT groups of 1-2 h and > 2 h produced greater yield outcomes of 68.2 to 72.6 kg for milk (P < 0.006), 2.06 to 2.15 kg for protein (P < 0.005), and 1.8 to 1.9 kg for fat (P < 0.045) for every 1 kg increase of weaning weight, respectively. The fit of all models was significantly improved with the inclusion of GPA. These results indicate that colostrum management and preweaning health measures impacted production parameters as adults. The inclusion of GPA significantly improved the accuracy of the models, indicating that this can be an important parameter to include in future studies.
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Affiliation(s)
- Elizah D McFarland
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3
| | - Ibrahim Elsohaby
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong SAR
| | - Christine F Baes
- Centre of Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, ON, Canada N1G 2W1
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern 3012, Switzerland
| | - Henrik Stryhn
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3
| | - Gregory Keefe
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3
| | - J T McClure
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3
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Gudra D, Valdovska A, Jonkus D, Galina D, Kairisa D, Ustinova M, Viksne K, Fridmanis D, Kalnina I. Genomic Characterization and Initial Insight into Mastitis-Associated SNP Profiles of Local Latvian Bos taurus Breeds. Animals (Basel) 2023; 13:2776. [PMID: 37685039 PMCID: PMC10487150 DOI: 10.3390/ani13172776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/27/2023] [Accepted: 08/28/2023] [Indexed: 09/10/2023] Open
Abstract
Latvia has two local Bos taurus breeds-Latvian Brown (LBG) and Latvian Blue (LZG)-characterized by a good adaptation to the local climate, longevity, and high fat and protein contents in milk. Since these are desired traits in the dairy industry, this study investigated the genetic background of the LBG and LZG breeds and identified the genetic factors associated with mastitis. Blood and semen samples were acquired, and whole genome sequencing was then performed to acquire a genomic sequence with at least 35× or 10× coverage. The heterozygosity, nucleotide diversity, and LD analysis indicated that LBG and LZG cows have similar levels of genetic diversity compared to those of other breeds. An analysis of the population structure revealed that each breed clustered together, but the overall differentiation between the breeds was small. The highest genetic variance was observed in the LZG breed compared with the LBG breed. Our results show that SNP rs721295390 is associated with mastitis in the LBG breed, and SNPs rs383806754, chr29:43998719CG>C, and rs462030680 are associated with mastitis in the LZG breed. This study shows that local Latvian LBG and LZG breeds have a pronounced genetic differentiation, with each one suggesting its own mastitis-associated SNP profile.
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Affiliation(s)
- Dita Gudra
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (D.G.); (M.U.); (K.V.); (D.F.)
| | - Anda Valdovska
- Faculty of Veterinary Medicine, Latvia University of Life Sciences and Technologies, LV-3001 Jelgava, Latvia
- Scientific Laboratory of Biotechnology, Latvia University of Life Sciences and Technologies, LV-3001 Jelgava, Latvia
| | - Daina Jonkus
- Faculty of Agriculture, Latvia University of Life Sciences and Technologies, LV-3001 Jelgava, Latvia (D.K.)
| | - Daiga Galina
- Faculty of Veterinary Medicine, Latvia University of Life Sciences and Technologies, LV-3001 Jelgava, Latvia
- Scientific Laboratory of Biotechnology, Latvia University of Life Sciences and Technologies, LV-3001 Jelgava, Latvia
| | - Daina Kairisa
- Faculty of Agriculture, Latvia University of Life Sciences and Technologies, LV-3001 Jelgava, Latvia (D.K.)
| | - Maija Ustinova
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (D.G.); (M.U.); (K.V.); (D.F.)
| | - Kristine Viksne
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (D.G.); (M.U.); (K.V.); (D.F.)
- Scientific Laboratory of Molecular Genetics, Riga Stradins University, LV-1007 Riga, Latvia
| | - Davids Fridmanis
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (D.G.); (M.U.); (K.V.); (D.F.)
| | - Ineta Kalnina
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (D.G.); (M.U.); (K.V.); (D.F.)
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Clasen JB, Fikse WF, Su G, Karaman E. Multibreed genomic prediction using summary statistics and a breed-origin-of-alleles approach. Heredity (Edinb) 2023:10.1038/s41437-023-00619-4. [PMID: 37231157 DOI: 10.1038/s41437-023-00619-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/11/2023] [Accepted: 04/26/2023] [Indexed: 05/27/2023] Open
Abstract
Because of an increasing interest in crossbreeding between dairy breeds in dairy cattle herds, farmers are requesting breeding values for crossbred animals. However, genomically enhanced breeding values are difficult to predict in crossbred populations because the genetic make-up of crossbred individuals is unlikely to follow the same pattern as for purebreds. Furthermore, sharing genotype and phenotype information between breed populations are not always possible, which means that genetic merit (GM) for crossbred animals may be predicted without the information needed from some pure breeds, resulting in low prediction accuracy. This simulation study investigated the consequences of using summary statistics from single-breed genomic predictions for some or all pure breeds in two- and three-breed rotational crosses, rather than their raw data. A genomic prediction model taking into account the breed-origin of alleles (BOA) was considered. Because of a high genomic correlation between the breeds simulated (0.62-0.87), the prediction accuracies using the BOA approach were similar to a joint model, assuming homogeneous SNP effects for these breeds. Having a reference population with summary statistics available from all pure breeds and full phenotype and genotype information from crossbreds yielded almost as high prediction accuracies (0.720-0.768) as having a reference population with full information from all pure breeds and crossbreds (0.753-0.789). Lacking information from the pure breeds yielded much lower prediction accuracies (0.590-0.676). Furthermore, including crossbred animals in a combined reference population also benefitted prediction accuracies in the purebred animals, especially for the smallest breed population.
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Affiliation(s)
- J B Clasen
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 7023, 75007, Uppsala, Sweden.
- Center for Quantitative Genetics and Genomics, Aarhus University, C. F. Møllers Allé 8, DK-8000, Aarhus, Denmark.
| | - W F Fikse
- Växa Sverige, Swedish University of Agricultural Sciences, Ulls väg 26, 756 51, Uppsala, Sweden
| | - G Su
- Center for Quantitative Genetics and Genomics, Aarhus University, C. F. Møllers Allé 8, DK-8000, Aarhus, Denmark
| | - E Karaman
- Center for Quantitative Genetics and Genomics, Aarhus University, C. F. Møllers Allé 8, DK-8000, Aarhus, Denmark
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Johnsson M. Genomics in animal breeding from the perspectives of matrices and molecules. Hereditas 2023; 160:20. [PMID: 37149663 PMCID: PMC10163706 DOI: 10.1186/s41065-023-00285-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 05/03/2023] [Indexed: 05/08/2023] Open
Abstract
BACKGROUND This paper describes genomics from two perspectives that are in use in animal breeding and genetics: a statistical perspective concentrating on models for estimating breeding values, and a sequence perspective concentrating on the function of DNA molecules. MAIN BODY This paper reviews the development of genomics in animal breeding and speculates on its future from these two perspectives. From the statistical perspective, genomic data are large sets of markers of ancestry; animal breeding makes use of them while remaining agnostic about their function. From the sequence perspective, genomic data are a source of causative variants; what animal breeding needs is to identify and make use of them. CONCLUSION The statistical perspective, in the form of genomic selection, is the more applicable in contemporary breeding. Animal genomics researchers using from the sequence perspective are still working towards this the isolation of causative variants, equipped with new technologies but continuing a decades-long line of research.
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Affiliation(s)
- Martin Johnsson
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 7023, Uppsala, 75007, Sweden.
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Blood Transcriptome Analysis of Beef Cow with Different Parity Revealed Candidate Genes and Gene Networks Regulating the Postpartum Diseases. Genes (Basel) 2022; 13:genes13091671. [PMID: 36140838 PMCID: PMC9498831 DOI: 10.3390/genes13091671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/05/2022] [Accepted: 09/15/2022] [Indexed: 11/16/2022] Open
Abstract
Maternal parity is an important physiological factor influencing beef cow reproductive performance. However, there are few studies on the influence of different calving periods on early growth and postpartum diseases. Here, we conducted blood transcriptomic analysis on cows of different parities for gene discovery. We used Short Time Series Expression Miner (STEM) analysis to determine gene expression levels in cows of various parities and divided multiple parities into three main periods (nulliparous, primiparous, and multiparous) for subsequent analysis. Furthermore, the top 15,000 genes with the lowest median absolute deviation (MAD) were used to build a co-expression network using weighted correlation network analysis (WGCNA), and six independent modules were identified. Combing with Exon Wide Selection Signature (EWSS) and protein-protein interaction (PPI) analysis revealed that TPCN2, KIF22, MICAL3, RUNX2, PDE4A, TESK2, GPM6A, POLR1A, and KLHL6 involved in early growth and postpartum diseases. The GO and KEGG enrichment showed that the Parathyroid hormone synthesis, secretion, and action pathway and stem cell differentiation function-related pathways were enriched. Collectively, our study revealed candidate genes and gene networks regulating the early growth and postpartum diseases and provided new insights into the potential mechanism of reproduction advantages of different parity selection.
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Cesarani A, Lourenco D, Tsuruta S, Legarra A, Nicolazzi E, VanRaden P, Misztal I. Multibreed genomic evaluation for production traits of dairy cattle in the United States using single-step genomic best linear unbiased predictor. J Dairy Sci 2022; 105:5141-5152. [DOI: 10.3168/jds.2021-21505] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 01/27/2022] [Indexed: 01/01/2023]
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Eiríksson JH, Karaman E, Su G, Christensen OF. Breed of origin of alleles and genomic predictions for crossbred dairy cows. Genet Sel Evol 2021; 53:84. [PMID: 34742238 PMCID: PMC8572482 DOI: 10.1186/s12711-021-00678-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 10/20/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In dairy cattle, genomic selection has been implemented successfully for purebred populations, but, to date, genomic estimated breeding values (GEBV) for crossbred cows are rarely available, although they are valuable for rotational crossbreeding schemes that are promoted as efficient strategies. An attractive approach to provide GEBV for crossbreds is to use estimated marker effects from the genetic evaluation of purebreds. The effects of each marker allele in crossbreds can depend on the breed of origin of the allele (BOA), thus applying marker effects based on BOA could result in more accurate GEBV than applying only proportional contribution of the purebreds. Application of BOA models in rotational crossbreeding requires methods for detecting BOA, but the existing methods have not been developed for rotational crossbreeding. Therefore, the aims of this study were to develop and test methods for detecting BOA in a rotational crossbreeding system, and to investigate methods for calculating GEBV for crossbred cows using estimated marker effects from purebreds. RESULTS For detecting BOA in crossbred cows from rotational crossbreeding for which pedigree is recorded, we developed the AllOr method based on the comparison of haplotypes in overlapping windows. To calculate the GEBV of crossbred cows, two models were compared: a BOA model where marker effects estimated from purebreds are combined based on the detected BOA; and a breed proportion model where marker effects are combined based on estimated breed proportions. The methods were tested on simulated data that mimic the first four generations of rotational crossbreeding between Holstein, Jersey and Red Dairy Cattle. The AllOr method detected BOA correctly for 99.6% of the marker alleles across the four crossbred generations. The reliability of GEBV was higher with the BOA model than with the breed proportion model for the four generations of crossbreeding, with the largest difference observed in the first generation. CONCLUSIONS In rotational crossbreeding for which pedigree is recorded, BOA can be accurately detected using the AllOr method. Combining marker effects estimated from purebreds to predict the breeding value of crossbreds based on BOA is a promising approach to provide GEBV for crossbred dairy cows.
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Affiliation(s)
- Jón H Eiríksson
- Center for Quantitative Genetics and Genomics, Aarhus University, 8830, Tjele, Denmark.
| | - Emre Karaman
- Center for Quantitative Genetics and Genomics, Aarhus University, 8830, Tjele, Denmark
| | - Guosheng Su
- Center for Quantitative Genetics and Genomics, Aarhus University, 8830, Tjele, Denmark
| | - Ole F Christensen
- Center for Quantitative Genetics and Genomics, Aarhus University, 8830, Tjele, Denmark
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8
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Falchi L, Gaspa G, Cesarani A, Correddu F, Degano L, Vicario D, Lourenco D, Macciotta NPP. Investigation of β-hydroxybutyrate in early lactation of Simmental cows: Genetic parameters and genomic predictions. J Anim Breed Genet 2021; 138:708-718. [PMID: 34180560 PMCID: PMC8518359 DOI: 10.1111/jbg.12637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 05/28/2021] [Indexed: 11/28/2022]
Abstract
Genomic information allows for a more accurate calculation of relationships among animals than the pedigree information, leading to an increase in accuracy of breeding values. Here, we used pedigree-based and single-step genomic approaches to estimate variance components and breeding values for β-hydroxybutyrate milk content (BHB). Additionally, we performed a genome-wide association study (GWAS) to depict its genetic architecture. BHB concentrations within the first 90 days of lactation, estimated from milk medium infrared spectra, were available for 30,461 cows (70,984 records). Genotypes at 42,152 loci were available for 9,123 animals. Low heritabilities were found for BHB using pedigree-based (0.09 ± 0.01) and genomic (0.10 ± 0.01) approaches. Genetic correlation between BHB and milk traits ranged from -0.27 ± 0.06 (BHB and protein percentage) to 0.13 ± 0.07 (BHB and fat-to-protein ratio) using pedigree and from -0.26 ± 0.05 (BHB and protein percentage) to 0.13 ± 0.06 (BHB and fat-to-protein ratio) using genomics. Breeding values were validated for 344 genotyped cows using linear regression method. The genomic EBV (GEBV) had greater accuracy (0.51 vs. 0.45) and regression coefficient (0.98 vs. 0.95) compared to EBV. The correlation between two subsequent evaluations, without and with phenotypes for validation cows, was 0.85 for GEBV and 0.82 for EBV. Predictive ability (correlation between (G)EBV and adjusted phenotypes) was greater when genomic information was used (0.38) than in the pedigree-based approach (0.31). Validation statistics in the pairwise two-trait models (milk yield, fat and protein percentage, urea, fat/protein ratio, lactose and logarithmic transformation of somatic cells count) were very similar to the ones highlighted for the single-trait model. The GWAS allowed discovering four significant markers located on BTA20 (57.5-58.2 Mb), where the ANKH gene is mapped. This gene has been associated with lactose, alpha-lactalbumin and BHB. Results of this study confirmed the usefulness of genomic information to provide more accurate variance components and breeding values, and important insights about the genomic determination of BHB milk content.
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Affiliation(s)
- Laura Falchi
- Department of Agricultural SciencesUniversity of SassariSassariItaly
| | - Giustino Gaspa
- Department of Agricultural, Forest and Food SciencesUniversity of TorinoTorinoItaly
| | - Alberto Cesarani
- Department of Agricultural SciencesUniversity of SassariSassariItaly
- Department of Animal and Dairy ScienceUniversity of GeorgiaAthensGAUSA
| | - Fabio Correddu
- Department of Agricultural SciencesUniversity of SassariSassariItaly
| | - Lorenzo Degano
- Associazione Nazionale Allevatori Pezzata Rossa (ANAPRI)UdineItaly
| | - Daniele Vicario
- Associazione Nazionale Allevatori Pezzata Rossa (ANAPRI)UdineItaly
| | - Daniela Lourenco
- Department of Animal and Dairy ScienceUniversity of GeorgiaAthensGAUSA
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Clasen JB, Kargo M, Østergaard S, Fikse WF, Rydhmer L, Strandberg E. Genetic consequences of terminal crossbreeding, genomic test, sexed semen, and beef semen in dairy herds. J Dairy Sci 2021; 104:8062-8075. [PMID: 33814139 DOI: 10.3168/jds.2020-20028] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 02/18/2021] [Indexed: 11/19/2022]
Abstract
The development of breeding tools, such as genomic selection and sexed semen, has progressed rapidly in dairy cattle breeding during the past decades. In combination with beef semen, these tools are adopted increasingly at herd level. Dairy crossbreeding is emerging, but the economic and genetic consequences of combining it with the other breeding tools are relatively unknown. We investigated 5 different sexed semen schemes where 0, 50, and 90% of the heifers; 50% of the heifers + 25% of the first-parity cows; and 90% of the heifers + 45% of the first-parity cows were bred to sexed semen. The 5 schemes were combined in scenarios managing pure-breeding or terminal crossbreeding, including genomic testing of all newborn heifers or no testing, and keeping Swedish Red or Swedish Holstein as an initial breed. Thus, 40 scenarios were simulated, combining 2 stochastic simulation models: SimHerd Crossbred (operational returns) and ADAM (genetic returns). The sum of operational and genetic returns equaled the total economic return. Beef semen was used in all scenarios to limit the surplus of replacement heifers. Terminal crossbreeding implied having a nucleus of purebred females, where some were inseminated with semen of the opposite breed. The F1 crossbred females were inseminated with beef semen. The reproductive performance played a role in improving the benefit of any of the tools. The most considerable total economic returns were achieved when all 4 breeding tools were combined. For Swedish Holstein, the highest total economic return compared with a pure-breeding scenario, without sexed semen and genomic test, was achieved when 90% sexed semen was used in heifers and 45% sexed semen was used for first-parity cows combined with genomic test and crossbreeding (+€58, 33% crossbreds in the herd). The highest total economic return for Swedish Red compared with a pure-breeding scenario, without sexed semen and genomic test, was achieved when 90% sexed semen was used in heifers combined with genomic test and crossbreeding (+€94, 46% crossbreds in the herd). Terminal crossbreeding resulted in lower genetic returns across the herd compared with the corresponding pure-breeding scenarios but was compensated by a higher operational return.
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Affiliation(s)
- J B Clasen
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 7023, 75007 Uppsala, Sweden.
| | - M Kargo
- Center for Quantitative Genetics and Genomics, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark; SEGES, Danish Agriculture and Food Council, Agro Food Park 15, DK-8200 Aarhus N, Denmark
| | - S Østergaard
- Department of Animal Science, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark
| | - W F Fikse
- Växa Sverige, Swedish University of Agricultural Sciences, Ulls väg 26, 756 51 Uppsala, Sweden
| | - L Rydhmer
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 7023, 75007 Uppsala, Sweden
| | - E Strandberg
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 7023, 75007 Uppsala, Sweden
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Cesarani A, Garcia A, Hidalgo J, Degano L, Vicario D, Macciotta NPP, Lourenco D. Genomic information allows for more accurate breeding values for milkability in dual-purpose Italian Simmental cattle. J Dairy Sci 2021; 104:5719-5727. [PMID: 33612221 DOI: 10.3168/jds.2020-19838] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 12/14/2020] [Indexed: 02/01/2023]
Abstract
Milkability is a trait related to the milking efficiency of an animal, and it is a component of the herd profitability. Due to its economic importance, milkability is currently included in the selection index of the Italian Simmental cattle breed with a weight of 7.5%. This lowly heritable trait is measured on a subjective scale from 1 to 3 (1 = slow, 3 = fast), and genetic evaluations are performed by pedigree-based BLUP. Genomic information is now available for some animals in the Italian Simmental population, and its inclusion in the genetic evaluation system could increase accuracy of breeding values and genetic progress for milkability. The aim of this study was to test the feasibility and advantages of having a genomic evaluation for this trait in the Italian Simmental population. Phenotypes were available for 131,308 cows. A total of 9,526 animals had genotypes for 42,152 loci; among the genotyped animals, 2,455 were cows with phenotypes, and the other were their relatives. The youngest cows with both phenotypes and genotypes (n = 900) were identified as selection candidates. Variance components and heritability were estimated using pedigree information, whereas genetic and genomic evaluations were carried out using BLUP and single-step genomic BLUP (ssGBLUP), respectively. In addition, a weighted ssGBLUP was assessed using genomic regions from a genome-wide association study. Evaluation models were validated using theoretical and realized accuracies. The estimated heritability for milkability was 0.12 ± 0.01. The mean theoretical accuracies for selection candidates were 0.43 ± 0.08 (BLUP) and 0.53 ± 0.06 (ssGBLUP). The mean realized accuracies based on linear regression statistics were 0.29 (BLUP) and 0.40 (ssGBLUP). No genomic regions were significantly associated with milkability, thus no improvements in accuracy were observed when using weighted ssGBLUP. Results indicated that genomic information could improve the accuracy of breeding values and increase genetic progress for milkability in Italian Simmental.
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Affiliation(s)
- A Cesarani
- Department of Animal and Dairy Science, University of Georgia, Athens, 30602.
| | - A Garcia
- Department of Animal and Dairy Science, University of Georgia, Athens, 30602
| | - J Hidalgo
- Department of Animal and Dairy Science, University of Georgia, Athens, 30602
| | - L Degano
- Associazione Nazionale Allevatori Pezzata Rossa Italiana (ANAPRI), 33100 Udine, Italy
| | - D Vicario
- Associazione Nazionale Allevatori Pezzata Rossa Italiana (ANAPRI), 33100 Udine, Italy
| | - N P P Macciotta
- Department of Agricultural Sciences, University of Sassari, 07100 Sassari, Italy
| | - D Lourenco
- Department of Animal and Dairy Science, University of Georgia, Athens, 30602
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