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USE AND DEVELOPMENT OF COLOMBIAN CREOLE BREEDS AND THEIR CONTRIBUTION TO THE PRODUCTIVE SYSTEMS RESILIENCE
Conservation programs. In Colombia, conservation programs were established since the middle of the last century. But only from the commitment acquired in the convention of Biological Diversity of Rio de Janeiro (1993), the Germplasm Banks of the Nation were officially established since 1994, for the Creole bovine breeds, Romosinuano, Costeño con Cuernos in the Centro de Investigación Turipaná, in Montería, Córdoba, Samartinero, in Centro de Investigaciones La Libertad in Villavicencio city, Departamento del Meta and a nucleus of Blanco Orejinegro breed in the Centro de Investigación El Nus, Antioquia. Later, to multiply and promote these breeds, a Development Program was developed (2005-2015) that allowed the increase of animal population, reaching to link 113 farms where a database with more than 6,000 productive records was generated (Vásquez et al. 2012). In 2012, the creation of two new germplasm banks began, one for Casanare breed, which currently has 200 animals and has allowed maintaining the genetic variability of this breed, and the other for the Hartón del Valle breed, in Valle del Cauca, which currently has 147 animals, formed into 5 family groups. Finally, in 2016, the germplasm bank of Chino Santandereano breed, made up of 40 animals, was created. These populations, because of their proven tolerance to tropical environments, constitute an important alternative to contribute to the resilience of livestock systems in Colombia and tropical regions of the world.
Programs of productive and genomic characterization in creole breeds. In these populations growth information (weight gain from birth to 24 months), reproductive characteristics (interval between parturitions, age at first parturition, scrotal circumference, etc.), adaptation characteristics, (heat tolerance index, coefficient of adaptability, tick load, etc.) and characteristics of productive type have been recorded for more than 30 years, with which a productive information base for genetic analysis was generated.
GENETIC IMPROVEMENT PROGRAM OF CREOLE BREEDS IN COLOMBIA
Development of performance tests and selection of genetically superior bulls. Since 2011, performance tests have been carried out on growing young bulls in Romosinuano and Blanco Orejinegro breeds, where it start in animals with 17 months and end at 24 months, the animals are selected through a composite index, which includes growth speed, adaptation, reproduction and type (Quiceno et al. 2011). Currently there are more than 360 evaluated bulls (55 bulls per test), 28 selected bulls in each of the breeds and 26,200 straws cryopreserved by breed, which are being used by farmers.
Creation of selection nucleus. The objective of this activity was to establish a base nucleus for the improvement of Romosinuano, Costeño con Cuernos, Sanmartinero and Blanco Orejinegro breeds, as a source of genetic variability for the selection of animals of high genetic value for livestock productionsystems. Currently the population groups are close to 400 animals in each selection nucleus and controlled matings are carried out, using bulls from the performance tests with follow-up to the coefficient of inbreedeng and breeding values for the characteristics under the improvement plan. The results show increasing breeding trends for growth and the average genetic values for the reproductive characteristics are stable.
Implementation of genomic selection tools. The reference population was established, from the databases, selecting those animals with the highest representation in the pedigree, with complete phenotypic information in the database and with higher values of accuracy in the genetic evaluations. For genotyping, a genotyping technology on a large scale was used, using a total of 3 200 animals genotyped with a 56K, 7k and 26k chip and for the imputation a procedure implemented with FImpute (Sargolzaei et al. 2014) was used.
Initially, genomic association analysis were carried out in order to determine the effect of specific SNPs on weights from birth to 24 months, finding an important region on chromosome BTA14 between 24 and 26 Mbp, in a region where the PLAG1 gene is found (Martínez et al. 2016). On the other hand, for the reproductive characteristics, a marker was found on BTA4, within the Leptin gene, as well as a marker within the POU3f gene on the BTA9 chromosome, which were significantly associated with the interval between parturitions in Romosinuano and Blanco Orejinegro breeds.
Results of the genomic evaluation. Currently, there is a reference population for each breed with complete productive and genomic information. An increase in the accuracy values was found for the use of genomic information, going from 0.55 to 0.6 for the birth weight at and from 0.25 to 0.37 in weaning weight, representing real increases ranging from 18 % to 25 % for the characteristics of birth weight and weaning weight respectively (Martinez et al. 2014). Likewise, this information is used to estimate the breeding values for the populations of the National Network of commercial farmers and associations to revitalize the valorization and genetic improvement of these breeds. The selection of creole breeds populations for growth characteristics, seeking to maintain their good reproductive performance and taking into account variables such as the adaptation coefficient and the heat tolerance index, will allow populations resilient to climatic variability and the prevailing difficult environmental conditions in tropical regions, such as tolerance to parasites and diseases, as one of the main approaches in this breeding program in creole breeds in Colombia.
GENOMIC PLATFORM IN CEBU BRAHMAN BREED
Methodology. To select the reference population in Cebu Brahman breed, 35 cattle herds were considered, located in 3 natural regions, eastern plains, inter-Andean valleys and north coast, and it was based on the historical database from the Asociación Colombiana de Criadores de Ganado Cebú - Asocebú, which has a total of 1 027 600 genealogical records in more than 7 effective generations. In order to consolidate the reference population, effective contribution analysis of individuals using PEDIG (Boichard et al. 2002) were carried out, which allowed to link a total of 85,000 animals in the genealogy for the genomic platform in the Cebu Brahman breed. The database considered growth characteristics, conformation evaluated by ultrasound, reproduction, linear classification, with a total of 165,000 data of phenotypic information. A total of 4 250 animals of the breed were genotyped using a chip specially designed for the Brahman breed, GENESEEK 76k and GENESEEK 26k, for the imputation process the FImpute software was used (Sargolzaei et al. 2014). For genomic analyzes, the mixed model methodology was used replacing the A-1 matrix with an H matrix that considers genomic contributions for genotyped individuals, using the Single Step Genomic BLUP (Best Linear unbiased Predictor) methodology, through the group of BLUPF90 programs (Misztal et al. 2009).
Predictive capacity. With the use of genomic information of approximately 4,250 genotyped animals, of which 895 were males and 3 165 females, where bulls with more than 10 offspring were selected and the 700 younger genotyped animals were used to cross-validate, as a result, a high prediction capacity was obtained, evidenced by a high correlation value (R2 = 0.85) between the genetic values and the genomic values for the validation population. Regarding the increase in the accuracy of prediction based on genomic information, it was found that the accuracy without genomic information for the population without genomic information varies between 0.17 to 0.30, which increases for the genotyped population to accuracy values between 0.30 and 0.47, with average increases of 37 %. Finally, the effects of the use of the mating schedule were estimated, for selection of sires in 20 farms, making the selection pilot (Martínez et al. 2018).
SELECTION STRATEGY IN SIMMENTAL BREED IN COLOMBIA
This is a start-up that is just beginning, in this case the Simmental Breeders Association provided the information consisting of genealogical information bases (N = 1,600), growth data (N = 18,000), milk production and quality (N = 7 500), linear classification (N = 1250) and finally the genotyping of a fraction of Colombia's Simmental cattle population (N = 700) using a medium density chip which containing a total of 30 thousand SNPs.
In the analysis of the genealogical information of Simmental cattle of Colombia a total of 27 985 animals were included, which were registered by the association between the years 1995 to 2017, distributed in 11,932 males and 14,658 females, which corresponded to a total of 3,282 sires and 9,378 dams. With this information it was possible to estimate the pedigree quality of Simmental breed in Colombia, where it was found that the sixth generation reached 60 % of the complete pedigree, in the estimation of the generational interval an average value of 9.5 years was obtained for the males and 6.5 years per interval for females. On the other hand, when estimating the tendencies of the inbreeding values in the population in the last 7 years, an increasing tendency was found, going from 0.01 to 0.016, besides estimating the tendencies in the effective size of Simmental population that passes from Ne=75 up to Ne 97.5 in 2016 and the contribution of breed lines of Simmental cattle, there was an increasing tendency of milk lines in both males and females, which shows that the majority of the population has focused on the productive specialization in Colombia.
Regarding the productive parameters in Simmental breed, for reproductive characteristics, there was a value of 1.165 ± 501 days for the age of the first parturition (n=3413), and an average value of 388 ± 157 days for interval between parturitions (n=3077). With respect to milk production at 305 days (n= 1,721) with an average value of 4,591 ± 1,754 liters, for fat percentage (n=2 440) an average value of 3.9 % +0.57 % and finally, for the protein percentage (n=2 820) a value of 3.4 ± 0.28 %.
The genomic base of Simmental breed was initially constructed by a total of 710 genotyped animals with a total of 80 males and 630 females (Amaya et al. 2018). This information has allowed carrying out more precise analysis of consanguinity and inbreeding and will provide the opportunity to perform a genetic evaluation including genomic information for the early selection of animals based on the genomic platform of the breed.
Laboratory of animal reproduction C.I. Tibaitatá. Created to be able to perform the multiplication of the identified superior individuals by means of the genomic selection tools previously described. This laboratory has an ICA Certification for production of reproductive material by totally in vitro methods, and has worked on the development of abilities in superovulation and embryo production by in vitro fertilization (IVF) methodologies, optimization of culture media and cryopreservation procedures for the production of embryos of high breeding value and at low cost (Pure and crosses -Milk-), for direct transfer estrus detected. In addition to developing strategies for staff training in embryo transfer techniques. From these developments, it has been possible to obtain more than 2,000 embryos of the Creole, Cebuina and Simmental breeds that are used to promote and spread the genetic progress of these selected breeds under tropical conditions, thus contributing to the livestock systems resilience to be used in tropical regions of the world.
CONCLUSION
There are state-of-the-art techniques that allow to obtain a more precise knowledge of the genetic structure of the populations and the genetic control of the characteristics, as well as to identify markers and regions of the genome that have an important effect on the phenotypic control and can be used combined with traditional information for genomic valuation that accelerates genetic gain, and combined with reproductive biotechnology strategies can make production systems more efficient.
