Allelic frequency of the Kappa-Casein gene in Colombian and creole cattle breeds

Summary Colombia has one of the most genetically diverse creole cattle populations, with eight creole breeds and two improved creole (Colombian) breeds. A high demand for meat and milk has led to the inevitable selection of highly productive cattle and the introduction of foreign breeds. Unfortunately, these breeds are often ill-suited for tropical conditions. These factors threaten the size of the creole livestock population, which is considered part of Colombia's national heritage. Objective : to estimate the allelic frequencies of the Kappa-Casein gene (CNS3) in Colombian creole cattle breeds (GCC). Methods : a total of 354 blood samples were taken from 30 animals of each of the following breeds: Blanco Orejinegro (BON), Caqueteno (CQT), Casanareno (CAS), Horned Costeno (Costeno con Cuernos, CCC), Chino Santandereano (ChS), Harton del Valle (HV), Romosinuano (ROM), and Sanmartinero (SM), each representing the 8 established "criollo" (creole) breeds; the Lucerna (LUC) and Velasquez (VEL) representing the two Colombian improved breeds; and Brahman and Holstein as control breeds. DNA was extracted by a salting-out procedure and a 453 bp fragment on chromosome 6 was amplified by PCR. CSN3 alleles were identified using single strand conformation polymorphism (SSCP) and their sequence compared with those of the Genebank for Bos taurus and Bos indicus. Results: higher frequencies for allele variants of CSN3 A (0.39) and B (0.41) were found relative to the frequencies of I (0.038), G (0.095), A 1 (0.025), E (0.006), and N (0.006). The allele of interest (CSN3 B) had a high frequency in the CCC (0.81), ROMO (0.66), CQT (0.55), ChS (0.48), and VEL (0.43) breeds. Conclusions: these findings suggest that Colombian creole breeds harbor a high genetic diversity which enriches its gene pool and warrants future conservation efforts to protect its integrity. Key words : genetic variants, milk proteins, molecular markers, PCR-SSCP . Resumen Colombia es uno de los paises mas diversos en recursos geneticos criollos. Posee ochos razas de ganado criollo (GCC) y dos razas de criollo mejorado o razas colombianas. La creciente demanda de alimentos ha generado una forzosa seleccion de individuos altamente productivos e introduccion de razas foraneas (Holstein y Brahman) poco adaptadas a condiciones tropicales, lo que ha puesto en riesgo el tamano efectivo del ganado criollo, considerado patrimonio nacional. Objetivo : estimar la frecuencia alelica del gen (CNS3) de la Kappa-Caseina en el (GCC). Metodos : se usaron 354 muestras de sangre de ocho razas bovinas criollas (30 individuos por raza): Blanco Orejinegro (BON), Caqueteno (CQT), Casanareno (CAS), Costeno con Cuernos (CCC), Chino Santandereano (ChS), Harton del Valle (HV), Romosinuano (ROMO) y Sanmartinero (SM), dos colombianas Lucerna (LUC) y Velasquez (VEL) y dos controles Brahman y Holstein. Con el fin de estimar la frecuencia de los alelos k-caseina (k-CN) se amplifico un fragmento de 453 pb para k-CN (cromosoma 6). Los alelos se identificaron mediante la tecnica PCR-SSCP. Resultados : se encontro mayor frecuencia para las variantes de k-CN A (0.39) y B (0.41), en comparacion a I (0.038), G (0.095), A 1 (0.025), E (0.006) y N (0.006). El alelo de interes k-CN B presento alta frecuencia en las razas CCC (0.81), ROMO (0.66), CQT (0.55), ChS (0.48), y VEL (0.43). Conclusiones : la alta frecuencia del alelo de interes del gen k-CN ratifica al GCC como alternativa viable en esquemas sostenibles de produccion de leche de mejor calidad y corrobora la necesidad de evaluacion y caracterizacion de recursos zoogenetico, como primer paso para su conservacion. Palabras clave : marcadores moleculares, PCR-SSCP, proteinas leche, variantes geneticas . Resumo A Colombia e um dos paises mais diversificado em recursos geneticos crioulos, tem oito bovinos da raca nativa e duas racas melhoradas ou racas crioulo colombiano (GCC). A alta demanda por alimentos tem levado a uma selecao forcada das pessoas altamente produtivas e/ou introducao de racas estrangeiras mal adaptados as condicoes tropicais, que tem prejudicado o tamanho efetivo de animais considerados patrimonio crioulo. Objetivo : estimar a frequencia do alelo do gene Kappa-Caseina (CNS3) na (GCC). Metodos : foram utilizados 354 amostras de sangue de oito racas nativas (30 individuos por raca): Blanco Orejinegro (BON), Caqueteno (CQT), Casanareno (CAS), Costeno con Cuernos (CCC), Chino Santandereano (ChS), Harton del Valle (HV), Romosinuano (ROM) e Sanmartinero (SM), dois Colombianas Lucerna (LUC) e Velasquez (VEL) e dois controles (Brahman and Holstein). Para estimar a frequencia de alelos de κ-caseina (CSN3), amplificaram um fragmento de 453 pb para CSN3. Os alelos foram identificados por PCR-SSCP. Resultados : encontramos uma maior frequencia de variantes do CSN3 A (0.39) e B (0.41), comparado com I (0.038), G (0.095), A 1 (0.025), E (0.006) e N (0.006). O alelo de interesse CSN3 B apresentou alta frequencia em racas CCC (0.81), ROMO (0.66), CQT (0.55), CHS (0.48) e VEL (0.43). Conclusoes : estes resultados sugerem que o CCG e um recurso genetico, que abriga uma grande diversidade genetica e apoia a necessidade de avaliacao e caracterizacao dos recursos geneticos animais como um primeiro passo para a conservacao. Palavras chave : marcadores moleculares, PCR-SSCP, proteinas do leite, variantes geneticas.