Abstract The goal of the present work was to estimate heritabilities, repeteabilities, and genetic and phenotypic correlations for production traits such as milk yield (MY; l/d), total fat (TF; g/d), total protein (TP; g/d), percentage of fat (F%; %), percentage of protein (P%; %), and subclinical mastitis (SCM, present or absent – based on Californian Mastitis Test) in lactations of 210 d long. To that purpose, test day records collected from 2009 to 2017 in an experimental farm (INTA EEA Anguil “Ing. Agr. Guillermo Covas”) were used. After editing, a total of 833 lactations were obtained from 425 Pampinta ewes, and, in turn, a genealogy with 1092 sheep was built. The following classificatory factors: age at first lambing (AFL); year and season of lambing (YSL); number of lambing (NL); lambing and weaning kind (LWK); days form lambing to first test day (DLFTD); and lactation length (LL) were tested for each response variable through univariate mixed models with repeated observations using the lme4 package in R. Among these, AFL was not selected for any model, while YSL was for all models. Besides, the model for MY did not include LWK; the one for TP did not include NL and LWK; for P% did not include LL; and for SCM did not include DLFTD and LL. For variance component estimations, bivariate animal mixed-models were used. These were estimated with a Bayesian approach using the TM program. Repeatability estimates for productive traits –MY, TF, TP, F%, P%– were intermediate, in the range from 0.41 to 0.51, showing that one observation could be a good predictor of individual productivity. On the other hand, for SCM the repeatability was 0.20; this is pointing the fact that environment plays such a great deal in the expression of that trait. In the case of heritabilities, the estimates were intermediate to low; for productive traits, they were between 0.21 and 0.33, in accordance with those in the bibliography. To the best of our knowledge, this is the first study to estimate heritability for SCM, which was 0.1. This value is slightly lower than that published for somatic cell counts. However, it seems possible to select against mastitis using SCM. Phenotypic and genetic correlations between MY with TF and with TP, and TF with TP were high, from 0.92 to 0.98, and these are in line with the literature. Phenotypic correlations between SCM and each productive trait were negative, which is good from a productive point of view; and the genetic correlations were positive, although they had very wide credibility intervals. Based on these estimates, if a selection program was put in place, for example, to increase MY and TF, a correlated response to selection could increase the incidence of SCM. Consequently, this fact should be taken into account to avoid negative consequences from the selection program.

Resumen El objetivo del presente trabajo fue estimar heredabilidades, repetibilidades y correlaciones genéticas y fenotípicas para los caracteres producción de leche (PL; l/d), grasa total (GT; g/d), proteína total (PT; g/d), porcentaje de grasa (G%; %) y de proteínas (P%; %), y mastitis subclínica (MSC, presencia/ausencia, según Test Mastitis California) en lactancias de 210 días en ovinos de la raza Pampinta. Se emplearon los controles lecheros realizados entre 2009 y 2017 en el tambo experimental del INTA, EEA Anguil “Ing. Agr. Guillermo Covas”. Luego de editarlos, se obtuvieron 833 lactancias de 425 ovejas Pampinta; a su vez, se construyó una genealogía con 1092 individuos. Los siguientes factores clasificatorios: edad al primer parto (EPP); año de parto y época de parto (AEP); orden de parto (OPAR); tipo de parto y crianza (TPC); días desde el parto al primer control lechero (DPPCL); y duración de lactancia (DLAC) fueron evaluados para cada variable respuesta mediante modelos mixtos unicarácter con observaciones repetidas empleando el paquete lme4 en R. De estos, EPP no resultó seleccionado para ningún modelo, en tanto que AEP lo fue para todos. Además, el modelo de PL no incluyó TPC; en de PT no incluyó OPAR y TPC; el de P% no incluyó ELAC; y el de MSC no incluyó DPPCL y ELAC. Para las estimaciones de componentes de varianza se emplearon modelos animales mixtos bicarácter con un enfoque bayesiano empleando el programa TM. Las estimaciones de repetibilidad para los caracteres de producción ─PL, GT, PT, G%, y P%─ fueron intermedias, entre 0,41 y 0,51, lo que indicó que una observación sería un buen predictor de la futura producción individual. En cambio para MSC fue de 0,20 resaltando la importancia del ambiente en la expresión de esta. Además, las estimaciones de heredabilidad resultaron intermedias a bajas para los caracteres de producción, entre 0,21 y 0,33, y baja para MSC, de 0,1. Para los caracteres de producción estas estimaciones están en el rango de las estimaciones reportadas previamente. Este estudio es el primero que reporta estimaciones de heredabilidad para mastitis subclínicas en ovinos, siendo levemente inferior a las estimaciones para recuentos de células somáticas reportadas por otros autores. Esto indica que se podría seleccionar indirectamente por resistencia a mastitis empleando MSC. Las correlaciones, fenotípicas y genéticas, entre PL con GT y con PT, y GT con PT resultaron altas con valores entre 0,92 y 0,98, coincidiendo con la bibliografía. Las correlaciones fenotípicas entre MSC y los caracteres productivos resultaron negativos. En tanto, las correlaciones genéticas resultaron todas positivas, pero con muy amplios intervalos de credibilidad. Estas estimaciones tienen una importancia práctica directa debido a que un programa de mejora genética para aumentar PL y GT aumentaría a su vez la incidencia de MSC. Esto pone de manifiesto la necesidad de incluir MSC en el objetivo de selección.

Cattle was absent from America before the discovery. Initially, bovine were brought to Greater Antilles (La Española, Puerto Rico, Jamaica and Cuba islands), and in the course of a few years, they were taken from Caribbean islands to the rest of Latin America. Nowadays, Cuban Creole cattle population is about 1300 heads, mainly located in the eastern region of the island. With the aim of analyzing the maternal origin of Cuban Creole cattle and detect possible contemporaneous, male mediated, gene flow, a 240 pb fragment of mitochondrial D-loop (mtDNA) and five microsatellites of Y chromosome (BTY) were studied in 36 dams and 21 sires, respectively. Genetic diversity was evaluated through number of haplotypes, mean number of pairwise differences and nucleotide diversity. The phylogenetic analysis was performed using a median joining. A total of 15 mtDNA haplotypes were detected in the studied population (10 from the European haplogroup T3, 3 from the African T1, 1 from the Nearern East T2, and 1 ambiguous T1-T3). The number of polymorphic sites, the mean nucleotide diversity, and the mean number of pairwise differences were 23, 0.014 and 3.36, respectively. Two patrilinages were detected, both belonging to the Y3 Zebu haplogroup. In conclusion, Cuban Creole cattle population had a mtDNA haplotypic composition similar to the observed in Creole and Mediterranean breeds, what is in concordance with its historical origin. Y chromosome analysis evidenced a male mediated process of zebu introgression.

Antes de descubrimiento, no existían bovinos en América. Los primeros, fueron introducidos en la Antillas Mayores (La Española, Puerto Rico, Jamaica y Cuba), y desde allí trasladados al resto de Latinoamérica. Actualmente, existen en Cuba alrededor de 1300 bovinos Criollos, concentrados principalmente en la región oriental. Con el objetivo de analizar el origen materno de esta raza y detectar eventos contemporáneos de flujo génico por vía paterna, se analizó un fragmento de 240 pb del D-loop mitocondrial (mtADN) y 5 microsatélites del cromosoma Y (BTY), en 36 hembras y 21 machos respectivamente. La diversidad genética se estimó mediante el número de haplotipos, el número de sitios polimórficos, el número de diferencias nucleotídicas entre pares de secuencias y el índice de diversidad nucleotídica, mientras que el análisis filogenético se realizó utilizando el método de median joining network. Dicho análisis permitió detectar 15 haplotipos mitocondriales (10 del haplogrupo europeo T3, 3 del africano T1, 1 del cercano oriente T2 y 1 ambiguo T1-T3) y 3 haplotipos en el BTY, ambos del haplogrupo cebuíno Y3. En el mtADN se detectaron 23 sitios polimórficos con una diversidad nucleotídica de 0,014 y 3,36 diferencias medias entre pares de secuencias. En conclusión, la población de bovinos Criollos Cubanos presentó una composición haplotípica mitocondrial comparable a la de otras razas criollas y mediterráneas, hecho que concuerda con su origen histórico. El BTY evidenció altos niveles de introgresion paterna de genes del zebú.

Data from five protein-coding loci related to dairy production were used to study the genetic diversity and population structure of Argentine and Bolivian Creole cattle breeds. Genomic DNA was extracted from blood samples of six Creole cattle breeds: Argentine (n = 230), Patagonian (n = 25); "Saavedreño" (n = 140), "Chaqueño Boliviano" (n = 30), "Yacumeño" (n = 27), and "Chusco" (n = 11). kappa-casein, beta-lactoglobulin, growth hormone and prolactin were measured by PCR-RFLP, while alphaS1-casein was typed by PCR-ASO. The results are discussed, focusing on: historical origin, recent differentiation and selection events, Zebu gene introgression, and population structure. This work shows that: (i) For the studied genes, the observed gene frequency profiles of Argentine and Bolivian Creole cattle breeds were close to the data reported for Iberian breeds and for other South-American Creole cattle breeds which are historically related; (ii) although Zebu gene introgression has been reported at the studied loci, these breeds seem to be far from the Zebu gene frequency profiles; and (iii) the Argentine and Bolivian Creole cattle showed significant levels of subdivision, but each population has maintained its degree of genetic variability.

Muitas raças de gado foram submetidas a alta pressão de seleção para caracteres de produção. Conseqüentemente, a estrutura genética e a distribuição alélica da população poderiam diferir em raças sob alta pressão de seleção, quando comparadas a raças não selecionadas. Foi feita a análise das freqüências dos genes de k-caseína, aS1-caseína e prolactina em rebanhos de gado Creole argentino (AC) e Hosltein argentino (AH). Os valores de FST calculados mediram o grau de diferenciação genética de subpopulações, dependendo de variações na freqüência dos genes. A raça AC apresentou variação consideravelmente maior entre os rebanhos nos loci de aS1-caseína e k-caseína. Estratégias de conservação devem considerar a população inteira de AC de forma a manter a variabilidade genética encontrada nesta raça nativa.

Many cattle breeds have been subjected to high selection pressure for production traits. Consequently, population genetic structure and allelic distribution could differ in breeds under high selection pressure compared to unselected breeds. Analysis of <FONT FACE="Symbol">k</font>-casein, <FONT FACE="Symbol">a</font>S1-casein and prolactin gene frequencies was made for Argentine Creole (AC) and Argentine Holstein (AH) cattle herds. The calculated FST values measured the degree of genetic differentiation of subpopulations, depending on the variances of gene frequencies.The AC breed had considerably more variation among herds at the <FONT FACE="Symbol">a</font>S1-casein and <FONT FACE="Symbol">k</font>-casein loci. Conservation strategies should consider the entire AC population in order to maintain the genetic variability found in this native breed.

Gene frequencies at the k-casein locus were estimated in six different herds (N = 180) of Argentinean Creole cattle. The results showed a strong influence of subdivision and independent evolution on the divergence of the observed gene frequencies. These results suggest that the population structure of these herds favor the maintenance of polymorphism, which is of crucial importance for the long-time survival of populations.