ABSTRACT
Resumen La inseminación artificial (IA) es actualmente el manejo reproductivo preferido para la mayoría de los ganaderos que trabajan con razas deganado internacionales como Holstein Friesian y Aberdeen Angus. En relación con esto, varios autores han descrito que a lo largo de los años ha habido una alteración en parámetros de productivos, lo que se asociaría significativamente con un aumento en el grado de endogamia en los animales. Esta situación tendría su origen a nivel de los núcleos genéticos, en los que se llevan a cabo programas de mejora, debido al pequeño número de líneas familiares a las que pertenecen los animales seleccionados como reproductores. Este estudio evaluó el grado de parentesco entre toros de inseminación Holstein Friesian y Aberdeen Angus comercializados en Chile por dos empresas de distribución de semen. Se estudiaron un total de 86 toros disponibles en catálogos hasta el año 2017. La información genealógica de cada toro se remonta hasta trastatarabuelo y luego se construyó un registro genealógico consolidado para cada raza. Este análisis consideró la estimación del porcentaje de endogamia (F) de cada toro y la construcción de una matriz de parentesco aditivo (A) entre los animales. Los resultados indicaron que el 99% de los toros Holstein y el 79% de los toros Angus están emparentados. Como resultado de lo anterior, se concluye que es esencial que en Chile se inicie un programa de gestión de información genealógica para controlar adecuadamente los niveles de endogamia y poder mitigar los problemas que puedan surgir a causa de este fenómeno.
Abstract Artificial insemination (AI) is currently the preferred reproductive management for most cattle farmers working with international cattle breeds likes Holstein Friesian and Aberdeen Angus. In relation to this, several authors have described that over the years there has been an alteration in the production parameters, which would be significantly associated with an increase in the inbreeding degree of the animals. This fact would have its origin at the genetic nucleus level, in which improvement programs are carried out, due to the small number of family lines which the animals selected as breeding stock belong to. This study evaluated the degree of kinship between Holstein Friesian and Aberdeen Angus insemination bulls marketed in Chile by two semen distribution companies. A total of 86 bulls available in catalogues until 2017 were studied. The genealogical information of each bull was traced back up to great-great-grandfather and then a consolidated genealogical record was built for each breed. This analysis considered the estimation of each bull's inbreeding percentage (F) and the construction of a co-ancestry matrix among animals. Results indicated that 99% of Holstein bulls and 79% of Angus bulls, are related to some extent. As a result of the above, it is concluded that is essential that in Chile a program management of genealogical information be initiated to adequately control inbreeding problems that may arise from the use of related animals.
Resumo A inseminação artificial (IA) atualmente é o manejo reprodutivo preferido da maioria dos criadores de gado que trabalham com raças de gado internacionais, como o Holstein Friesian e o Aberdeen Angus. Nesse âmbito, vários autores assinalam que, ao longo dos anos, tem ocorrido uma alteração dos parâmetros produtivos, que poderia estar associada de forma significativa com um aumento no nível de endogamia nos animais. A origem dessa situação poderia estar nos núcleos genéticos, pois nos programas de melhoria, os animais que são selecionados como reprodutores pertencem a um reduzido número de linhas familiares. Esta pesquisa avalia os graus de parentesco entre touros para inseminação Holstein Friesian e Aberdeen Angus comercializados no Chile por duas empresas de distribuição de sêmen. No total, 86 touros foram analisados, disponíveis em catálogos de até 2017. As informações genealógicas de cada touro remontam aos tetravós. Posteriormente, foi elaborado um registro genealógico consolidado para cada raça. A análise considerou a estimação da porcentagem de endogamia (F) de cada touro e a construção de uma matriz de parentesco aditivo (A) entre os animais. Os resultados indicam que 99% dos touros Holstein e 79% dos touros Angus são aparentados. Como resultado disso, chega-se à conclusão de que é essencial se ter um programa de gestão de informações genealógicas no Chile para controlar adequadamente os níveis de endogamia e assim mitigar os possíveis problemas gerados por esse fenômeno.
ABSTRACT
Vaccinium meridionale es una planta silvestre productora de frutos comestibles en las áreas montañosas del norte de Suramérica. Sin embargo, no hay información suficiente sobre su sistema reproductivo, lo cual es fundamental para su manejo y conservación dado que sus frutos son extraídos de forma no sostenible y hay un creciente interés en establecer la especie como cultivo. Los objetivos de este trabajo fueron estudiar la biología floral y reproductiva de V. meridionale en condiciones naturales y analizar la importancia de los polinizadores en su reproducción. Para esto se realizaron observaciones y experimentos para describir su morfología y fenología floral, viabilidad de polen, receptividad de estigma, relación polen óvulo y producción de néctar. Para estudiar su sistema reproductivo se realizaron experimentos de emasculación, exclusión de polinizadores y polinización manual (autopolinización y polinización cruzada). El estudio se realizó con dos poblaciones silvestres de V. meridionale ubicadas en los departamentos de Cundinamarca y Boyacá, en la Cordillera Oriental de Colombia. Se encontró que aunque las flores tienen anteras poricidas la liberación del polen se da fácilmente sin vibración. V. meridionale presenta un gran despliegue y larga longevidad floral y hay un sesgo en la producción de néctar hacia la función femenina. Se estimó una relación polen/óvulo de 571±133, lo que clasifica a la especie como xenógama facultativa. Este resultado coincidió con los experimentos de polinización ya que en las dos poblaciones estudiadas las plantas produjeron frutos por agamospermia, autogamia y xenogamia. No obstante, se observó una fuerte depresión por endogamia manifestada en altas tasas de aborto de frutos producidos por autogamia a diferencia de los frutos provenientes de polinización cruzada que fueron retenidos por la planta desde su formación. Los rasgos florales presentados por la especie se consideran mecanismos para favorecer un gremio más diverso de visitantes florales que sólo los insectos capaces de polinización por vibración. Además, estos rasgos florales pueden aumentar la probabilidad de polinización y disminuir la geitonogamia. Igualmente la depresión por endogamia sugiere que la especie busca mantener el entrecruzamiento como su principal estrategia reproductiva. Por lo tanto, los polinizadores, en particular las abejas son fundamentales para la reproducción de V. meridionale y en consecuencia su conservación es esencial para mantener la variabilidad genética y oferta de frutos de esta especie.
Vaccinium meridionale is a wild plant producing edible fruits in the mountain areas of Northern South America. However, the fruits of this species has been under an unsustainable extraction and there is a growing interest of establishing this species as a crop; nevertheless, the information about its breeding system is scarce, which is essential for its sustainable management and conservation. This research aimed to study the floral and reproductive biology of V. meridionale in natural conditions, and to analyze the importance of pollinators on its reproduction, in two wild populations of V. meridionale in the states of Cundinamarca and Boyacá, in the Oriental Cordillera of Colombia. For this, we have made different observations and experiments to describe its flower morphology, floral phenology, pollen viability, stigma receptivity, pollen-ovule ratio and nectar production. To study its reproductive system, we performed experiments of flower emasculation, pollinator exclusion and hand pollination (self-and cross-pollination). We found that although the flowers have poricidal anthers, the release of pollen could occur easily without vibration. V. meridionale shows a large floral display, long floral longevity and has female-biased nectar production. The pollen-ovule ratio was of 571±133, which classified the species as facultative xenogamy. This result agreed with the pollination experiments because the plants produced fruits by agamospermy, selfing and outcrossing. However, we registered a strong inbreeding depression, observed in high rates of fruit abortions, after self-pollination. Unlike of self-pollinating fruits, the plant retains those produced by cross-pollination since its formation. The floral traits showed by this species are mechanisms to favor a more diverse guild of floral visitors than only insects able to buzz-pollination. In addition, these floral traits may enhance the pollination probability, and reduce geitonogamy. Moreover, the inbreeding depression suggests that V. meridionale promotes outcrossing as its main reproductive strategy. Therefore, pollinators, particularly bees, are essential for this species reproduction and conservation, and are critical in the maintenance of its genetic variability and fruits production.
ABSTRACT
Tomato varieties having less number of locules, thicker pericarp and good firmness are preferred by the consumers. A set of 28 half diallel crosses were generated by crossing 8 inbred lines of tomato (Lycopersicon esculentum Mill) namely Gujarat Tomato 1 (GT 1), Pusa Ruby, H 24, Ec 490190, Arka Vikas, Ec 163599, Ec 177371 and Ec 398704. Parents, F1 hybrids and F2 populations using randomized complete block design with three replications were evaluated for fruit weight, equatorial and polar diameter, number of locules, pericarp thickness and firmness at Junagadh Agricultural University, Junagadh (Gujarat, India). Significant genetic differences were observed among the parents, their F1 hybrids and F2 populations for fruit firmness related characters except locules fruit-1 under study. The cross Arka Vikas x Ec 398704 followed by GT 1 X Ec 490190 and Pusa Ruby X Ec 163599 exhibited higher heterobeltiosis as well as standard heterosis along with considerable inbreeding depression for fresh fruit firmness hence, is desired for firm fruited tomato plants and would score over yield when tomato are cultivated for distant markets. This cross also involved at least one parent having grater firmness as well pericarp thickness and few locules, hence, can be recommended for breeding improved fruit firmness lines in future.
ABSTRACT
Estimou-se o coeficiente de endogamia e avaliou-se seu efeito sobre características morfométricas dos animais em um criatório no norte de Minas Gerais. As características estudadas foram alturas da cernelha e da garupa, comprimentos da cabeça, do pescoço, do dorso-lombo, da garupa e do corpo, larguras do peito e da garupa. O arquivo continha 2186 informações de parentesco de animais do arquivo zootécnico da fazenda, desde o início da formação da raça, 1951, até o ano de 2006. Calculou-se o coeficiente de endogamia (F) e avaliou-se seu efeito por meio de regressão linear simples sobre as medidas morfométricas. Do total de animais, 27,6% mostraram-se endogâmicos, sendo o F médio da população igual a 1,4%. Considerando-se apenas os animais endogâmicos, a consanguinidade média atingiu 5,3%, mínimo de 0,1 e máximo de 28,1%. Não se verificaram efeitos negativos da endogamia sobre as características morfométricas, exceto para largura da garupa, em que se observou que para cada 10% de acréscimo de F houve aumento de 0,576cm na largura da garupa. Possivelmente, devido ao baixo valor encontrado, a endogamia não influenciou as demais características avaliadas.
The coefficient of inbreeding was estimate and its effect on linear traits of the Mangalarga Marchador horses reared in a ranch in the North of Minas Gerais was evaluated. The characteristics studied were morphometric traits such as wither and hip height, length of head, neck, back-loin, hip and body, as well as chest and hip width. The archive had 2186 data on the genealogy of animals from the herd register of the Catuni Farm. The coefficient of inbreeding (F) was calculated and its effect was evaluated by means of simple linear regression on the linear traits. Of all animals, 27.6% showed inbreeding, with an F average of 1.4% in the population. Considering only the inbred animals, the average consanguinity reached 5.3% minimum of 0.1 and maximum of 28.1%. Negative effects of inbreeding on the morphometric traits were not seen, except for hip width, where for each 10% increase in F there was increase of 0.576cm. Possibly due to the low value found, inbreeding did not influence the other evaluated characteristics.
ABSTRACT
Effects of inbreeding have been studied on diverse traits namely mortality, selection intensity and anthropometric traits in socio-economically divergent castes with different inbreeding levels taking into consideration the extent of marital migration and assortative marriage by profession in these populations. Mala, Madiga of the scheduled castes and Reddy, Vvsya and Maheshwari of the forward castes constituted the sample populations. Analysis of inbreeding effects revealed low mortality load, high selection intensity and inbreeding elevation of anthropometric traits in the forward castes. Wide differences in parameters of populations structure such as inbreeding, marital migration, assortative marriage by profession and gene-environment interactions could be causing differences in homozygosities of deleterious/ ill adapted genes in these castes leading to the results observed.