Genetic polymorphism of the \u3b1s1-casein locus in five populations of goats from Mexico

With the objective of estimating allele frequencies, and testing for population divergence for the CSN1S1 locus, genotypes of animals from five goat populations; Saanen (n = 97), Alpine (n = 81) Toggenburg (n = 92), local goats with external appearance similar to the Murciana-Granadina breed from Central Mexico (n = 26) and heterogeneous local animals denominated Mosaico Lagunero (n = 30), from Northern Mexico, were identified using PCR and Xmn1 PCR-RFLP methodology. For Saanen, Alpine and Toggenburg, the sum of E and F alleles had the largest frequencies (from 0.468 to 0.789), while for the groups local Murciana-Granadina and Mosaico Lagunero the sum of the most frequent allelic groups (A* and B*), were 0.385 and 0.533 respectively. Both local Murciana-Granadina and Mosaico Lagunero populations showed heterozygote excess (P < 0.08). The percentage of the total genetic variation (FST) explained by population differences was 5.16. There was genetic differentiation for most pair comparisons between populations (P < 0.05), excepting for Alpine versus Toggenburg, and Toggenburg versus Mosaico Lagunero (P > 0.05). For Saanen and Alpine the frequencies of alleles E and F were similar to the same breeds previously analyzed in Europe. Therefore there are opportunities of increasing the frequency of the strong alleles for protein content Gene Assisted Selection (GAS) in these two breeds. For Toggenburg the most frequent allelic groups were F (0.32) and B* (0.21). Results indicate differentiation between most populations for this locus. Moreover, heterozygote excess in local populations indicated breed admixture

Genetic parameters for milk yield and reproduction traits in the Chilean Dairy Overo Colorado cattle breed

The objective of this study was to estimate genetic parameters for milk production and reproduction traits using phenotypic and pedigree information from the Dairy Overo Colorado breed from southern Chile. Single- and multi-trait mixed models were used to analyze the data. Analyses were performed using ASReml software. The heritability estimates for milk yield, fat yield, protein yield, fat content, protein content, age at first calving and calving interval were 0.29 ± 0.04, 0.34 ± 0.04, 0.30 ± 0.04, 0.56 ± 0.04, 0.56 ± 0.04, 0.01 ± 0.07 and 0.002 ± 0.02, respectively. The genetic correlations between yield traits were high and positive (≥ 0.81). The genetic correlations of milk yield with fat content (-0.32) and protein content (-0.34) were unfavorable. The genetic correlation estimates between age at first calving and yield traits were negative, ranging between -0.71 and -0.29. The phenotypic correlations between calving interval and milk yield traits were slightly positive (0.06-0.09), suggesting a weak relationship between reproduction and yield in this population. Genetic variation was significantly greater than zero for milk production traits. Genetic improvement for age at first calving and calving interval may be slow because small differences between animals and low reliabilities are expected for estimated breeding values for these traits due to heritabilities close to zero. The design of an efficient breeding program for yield traits based on artificial insemination for this population is feasible using either progeny testing or genomic breeding value prediction to select sires.El objetivo de este estudio fue estimar parámetros genéticos para características de producción de leche y reproducción en la raza Overo Colorado Lechero del sur de Chile. Se utilizaron modelos de una y múltiples características para analizar los datos. Los análisis se realizaron usando el programa ASReml. Los estimados de heredabilidad para producción de leche, producción de grasa, producción de proteína, contenido de grasa, contenido de proteína, edad al primer parto e intervalo entre partos fueron 0.29 ± 0.04, 0.34 ± 0.04, 0.30 ± 0.04, 0.56 ± 0.04, 0.56 ± 0.04, 0.01 ± 0.07 y 0.002 ± 0.02, respectivamente. Las correlaciones genéticas entre las características de producción fueron altas y positivas (≥ 0.81). Las correlaciones genéticas de la producción de leche con el contenido de grasa (-0.32) y el contenido de proteína (-0.34) fueron desfavorables. La correlación genética entre edad al primer parto y las características de producción fueron negativas entre -0.71 and -0.29. Las correlaciones fenotípicas entre el intervalo entre partos y las características de producción de leche fueron ligeramente positivas, (0.06-0.09), lo que sugiere una relación débil entre reproducción y producción en esta población. La variación genética es significativamente mayor a cero para las características de producción de leche. El mejoramiento genético para edad al primer parto e intervalo entre partos será lento, debido a que se esperan pequeñas diferencias entre animales y bajas confiabilidades para los valores genéticos estimados, debido a que los valores de las heredabilidades son cercanos a cero. El diseño de un programa eficiente de mejoramiento genético para características de producción basado en inseminación artificial para esta población es factible usando pruebas de progenie o predicciones del valor genético aditivo usando evaluaciones genómicas para la selección de sementales

Effects of crossbreeding on milk production and growth characteristics in dual-purpose cattle in humid tropics

Crossbreeding effects were evaluated in three dual purpose bovine sub-populations in the tropics, and 5,040 lactations, 4,429 birth weights and adjusted weights at 205 [3,878], 365 [3,017] and 540 [2,276] days (PN, P205, P365 y P540, respectively) from Zebu cattle (CE) and its crosses with Holstein (HS), Brown Swiss (SP) and Simmental (SM). Additive direct breed effects (PG), heterozygosity (HT) and recombination loss (RC) were estimated by a regression analysis within breed group with mixed models. Evaluated fixed effects were herd and year of freshening, season, lactation number and offspring gender for milk yield (PL) and herd, birth year and season for growth traits. Random effects for PL were direct (animal) and permanent environment and for growth traits were genetic direct and maternal and permanent maternal environmental effects. PG/HS, PG/SP y HT/SM had effects (P<0.10) on PL while PG/SP, PG/SM, HT/SM and RC/HS on PN. PG/HS y PG/SP presented effects (P<0.10) on P205, P365 and P540 while PG/SM only on P205. HT and RC had effects (P<0.10) on P205, P365 y P540 for all crosses. Results hereby presented will allow the formulation of strategies for the use of additive and non-additive genetic effects of the crossbred populations present in the Mexican humid tropical regions

Genotype × environment interaction for fertility and milk yield traits in Canadian, Mexican and US Holstein cattle

The objective of this study was to evaluate genotype × environment interaction (G×E) between Canada, the United States and Mexico for fertility and milk yield traits using genetic correlations between countries estimated from genetic evaluations of sires. Genetic correlation between Mexican and Canadian Holsteins for age at first calving was ≤ 0.48 and lower than the simulated value obtained accounting for data structure and selection effects. For calving interval, genetic correlation between Mexico and Canada ranged from 0.48 to 0.69. Genetic correlation between calving interval in Mexico (multiplied by -1) and daughter pregnancy rate in the United States ranged from 0.64 to 0.73, and was lower than simulated and actual Canada-United States values. Genetic correlations between Mexico and Canada and the United States for milk yield traits were ≥ 0.83, similar to simulated genetic correlations, but lower than Canada-United States values (≥ 0.93). Heritability estimates for age at first calving, calving interval, milk yield, fat yield, protein yield, fat content, and protein content for the Mexican Holstein population were 0.06, 0.03, 0.18, 0.20, 0.19, 0.46, and 0.49, respectively. G×E interaction effects between Canada and Mexico for age at first calving were high, whereas G×E interaction effects between Canada and Mexico for calving interval and between daughter pregnancy rate in the United States and calving interval in Mexico were moderate. G×E interaction effects for milk yield traits between Canada or the United States with Mexico in registered Holsteins were low

Genetic polymorphism of the αs1-casein locus in five populations of goats from Mexico

With the objective of estimating allele frequencies, and testing for population divergence for the CSN1S1 locus, genotypes of animals from five goat populations; Saanen (n = 97), Alpine (n = 81) Toggenburg (n = 92), local goats with external appearance similar to the Murciana-Granadina breed from Central Mexico (n = 26) and heterogeneous local animals denominated Mosaico Lagunero (n = 30), from Northern Mexico, were identified using PCR and Xmn1 PCR-RFLP methodology. For Saanen, Alpine and Toggenburg, the sum of E and F alleles had the largest frequencies (from 0.468 to 0.789), while for the groups local Murciana-Granadina and Mosaico Lagunero the sum of the most frequent allelic groups (A* and B*), were 0.385 and 0.533 respectively. Both local Murciana-Granadina and Mosaico Lagunero populations showed heterozygote excess (P < 0.08). The percentage of the total genetic variation (FST) explained by population differences was 5.16. There was genetic differentiation for most pair comparisons between populations (P < 0.05), excepting for Alpine versus Toggenburg, and Toggenburg versus Mosaico Lagunero (P > 0.05). For Saanen and Alpine the frequencies of alleles E and F were similar to the same breeds previously analyzed in Europe. Therefore there are opportunities of increasing the frequency of the strong alleles for protein content Gene Assisted Selection (GAS) in these two breeds. For Toggenburg the most frequent allelic groups were F (0.32) and B* (0.21). Results indicate differentiation between most populations for this locus. Moreover, heterozygote excess in local populations indicated breed admixture