Zugl.: Giessen, Univ., Diss., 2009

Universiẗat, Diss., 2007--Giessen.

The need for a more reliable method to select beef heifers to retain as replacement dams has become a concern in the beef industry. Two polymorphisms described in leptin (LEP), p.Arg25Cys, and pro-melanin concentrating hormone (PMCH), g.-134A>T, have already been shown to improve carcass quality in beef cattle. This study was designed to evaluate any additional advantages of these polymorphisms in terms of heifer conception and calving success and lactational milk yield measured indirectly by their calves’ early ADG while they were primarily on lactation. A dominant effect of the dam’s PMCH T allele was observed on improved calf early ADGs in Simmental heifer dams, although not in Angus heifer dams. This effect could be useful in cow-calf operations where calves were suckling their dams for a longer period before sending the cow-calf pairs out to summer pasture. The dam LEP genotype did not show an effect on their calves’ ADG. This was assumed to be due to low body fat reserves of the heifer dams at the age of two years, allowing for only low levels of leptin. Even though heifer conception was not affected by their LEP and PMCH genotypes, it would be worth evaluating their rebreeding success in the presence of these SNPs in the future. The Integral Membrane Protein 2A (ITM2A) was hypothesized as a candidate gene for frame size in cattle. DNA fragments from 20 cattle, matching the predicted exons of the cattle ITM2A gene, were sequenced to determine whether genetic variation existed. However, the sequence obtained based on the predicted cattle ITM2A sequences appeared to be a pseudogene, rather than the actual cattle ITM2A gene, because exons 1, 2, 3 and 5 contained stop codons. Since frame size has been reported to be associated with the reproductive performance of beef dams and their calves’ growth characteristics, it would be useful to characterize this gene once an improved cattle genome assembly is available.

Orientador: Elton Eustáquio Casagrande / Manoel Fernando Martins / Ana Claudia Fernandes Terence / Resumo: A cadeia de carne bovina possui posição de destaque no contexto da economia rural brasileira, ocupando vasta área do território nacional e respondendo pela geração de emprego e renda de milhões de brasileiros. Contudo, para atender as demandas da sociedade moderna, é preciso avançar na produção de produtos mais diferenciados. Neste sentido, ganham relevância as estratégias empresariais nos diversos elos da cadeia produtiva da carne bovina, sobretudo no subsistema de industrialização. Na cadeia produtiva da carne bovina brasileira, um dos programas de destaque com essa finalidade é o Programa Carne Angus Certificada. Este trabalho, classificado como uma pesquisa aplicada, de natureza exploratória, de abordagem qualitativa, no contexto de uma análise de interação setorial, feita através de um procedimento de estudo multicaso, descreveu e analisou a estrutura competitiva e o comportamento estratégico dos frigoríficos participantes do Programa Carne Angus Certificada em São Paulo, com suporte das teorias do Modelo das Cinco Forças de Porter e das Tipologias Estratégicas de Miles e Snow. A coleta de dados se deu através de entrevista semiestruturada, realizada com quatro indústrias frigoríficas participantes do programa no estado, que contou com roteiro pré-determinado e perguntas avaliativas feitas após as respostas dadas com auxílio de itens da escala Likert (estrutura competitiva) e respostas às questões de múltipla escolha (comportamento estratégico). Os resultados para a estr... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The beef production chain has a prominent position in the context of the Brazilian rural economy, occupying a large area of the national territory and responding to the generation of employment and income for millions of Brazilians. However, to meet the modern society demands, it is necessary to move forward in the production of differentiated products. In this sense, corporate strategies gain importance in the beef production chain channels, especially in the industrialization subsystem. In the Brazilian beef production chain, one of the main programs for this purpose is the Certified Angus Beef Program. This work, classified as an applied research, of an exploratory nature, with a qualitative approach, in the context of a sectorial interaction analysis, made through a multicase study procedure, described and analyzed the competitive structure and strategic behavior of the meatpackers participating in the Program Angus Beef Certified in São Paulo, with support from Porter's Five Forces Model theories and Miles and Snow Strategic Typologies. Data were collected through a semistructured interview, conducted with four meatpacking industries participating in the program in the state, which had a predetermined script and evaluative questions made after the answers given using Likert scale items (competitive structure) and responses to multiple choice issues (strategic behavior). The results for the competitive structure indicated that the threat of new competitors and the power o... (Complete abstract click electronic access below) / Mestre

Submitted by CLARISSA HELENA SANTANA null (santana.chs@gmail.com) on 2016-03-21T18:17:24Z No. of bitstreams: 1 Dissertação_Clarissa_Helena_Santana.pdf: 1159982 bytes, checksum: 1160868d6c0bff2c67119202847275c7 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-03-22T17:26:26Z (GMT) No. of bitstreams: 1 santana_ch_me_jabo.pdf: 1159982 bytes, checksum: 1160868d6c0bff2c67119202847275c7 (MD5) / Made available in DSpace on 2016-03-22T17:26:26Z (GMT). No. of bitstreams: 1 santana_ch_me_jabo.pdf: 1159982 bytes, checksum: 1160868d6c0bff2c67119202847275c7 (MD5) Previous issue date: 2016-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A bovinocultura é um setor com importante destaque no agronegócio brasileiro. O carrapato Ripicephalus (Boophilus) microplus é responsável por perdas econômicas significativas aos pecuaristas e é vetor de hemoparasitoses como Anaplasma spp e Babesia spp. Sabe-se que os bovinos Bos taurus taurus são mais susceptíveis à infestação por carrapatos do que Bos taurus indicus. Acredita-se que o mesmo ocorra para a infecção por Babesia bovis. Neste trabalho, foram avaliados, em duas colheitas, 355 bovinos da raça Angus, pertencentes a uma fazenda de Uruguaiana-RS, nos quais foram realizadas contagens de carrapatos e colheitas de amostras de sangue para quantificação de B. bovis, pela técnica de qPCR, e genotipagem com chip de 150.000 marcadores SNP. Para qPCR utilizaram-se sequências iniciadoras que flanqueiam um fragmento do gene do citocromo B (mt-cytB), como oligonucleotídeos iniciadores. Após genotipagem dos bovinos com o chip Gene Seek Genomic Profiler™ (GGP-HD) da Illumina Infinium®, foi realizado imputação de genótipos, para recuperação de genótipos faltantes, e controle de qualidade. Foi realizada análise de associação genômica ampla (GWAS), para cada uma das características, infecção por B. bovis e resistência a carrapatos, através do método denominado “Single Step Genomic BLUP” (ssGBLUP). Todos os animais apresentaram infestação por carrapatos e infecção por B. bovis, determinada pela qPCR, e altos valores médios para ambas as características. Algumas regiões cromossômicas foram identificadas como significativas para as características estudadas, sendo que, sete dos cromossomos identificados no presente estudo já haviam sido descritos em outros trabalhos. Neste sentido, o presente estudo corrobora com outros resultados indicando que a técnica de qPCR é um método sensível de detecção de B. bovis em animais Angus e que as regiões genômicas identificadas como significativas podem ser importantes para a variação das características estudadas. / The cattle industry is a sector with importance in the Brazilian agribusiness. The Ripicephalus (Boophilus) microplus is responsible for economic losses and is a vector for hemoparasitoses, such as Anaplasma spp and Babesia spp. It is known that the Bos tauros animals are more susceptible to infestation by ticks when compared with infestation in Bos indicus animals. It is believed that the same behavior keeps for infection by Babesia bovis. They were evaluated, in two collections, 355 Angus cattle, from a farm in Uruguaiana city, estate of Rio Grande do Sul, where were performed tick counts, quantification of B. bovis by qPCR and genotyping with a 150K chip. Were used as primers, in the qPCR, sequences that flanking the fragment of the cytochrome b gene. The technique was standardized and optimized using specimens of isolates of B. bovis. After genotyping, imputation was carried out, for recovery of missing genotypes, and quality control. Genome association analysis was performed (GWAS), to each of the characteristics, through the method called "Single Step Genomic BLUP" (ssGBLUP). All animals showed tick infestation and infection by B. bovis and high average values for both characteristics. Some regions on chromosomes were identified as significant to the characteristics tick infestation and infection by B. bovis, and seven chromosomes, identified in the present study, were already described in other studies. The present study agrees with other results indicating that the qPCR technique is a sensitive method to detecting B. bovis in Angus and genomic regions identified may be significant for the variation of these characteristics.

The objective was to determine how the interaction of implant strategies with the galanin receptor 2 genotype would influence feeding behavior, production efficiencies, carcass characteristics, and meat quality in finishing steers. Angus steers were selected based on GALR2-c.-199T>G genotype (n = 36 TT, 38 TG, and 19 GG). Calves were blocked by body weight and fed a standard feedlot ration, blood and BW were collected every 28 d. Steers were randomly assigned to an implant strategy of Revalor-S (1×) or Revalor-S (2×). Intake and feeding behavior data were individually recorded. There was an effect of genotype on DMI but not feed efficiency. Treatment interactions were observed for several meat quality attributes but not carcass characteristics. Altering implant strategy does not appear to interact with the GALR2-c.-199T>G genotype to alter production or carcass characteristics.

The thesis is focused on the growth intensity of Aberdeen Angus, Charolais and Limousine. In experiment A, 152 male animals were monitored. These bulls came from organic and conventional breeding. For bulls, the date of birth, birth weight, father's line, date of sale, and live weight of bulls at sale were followed. Experiment B included 88 female heifers. Within each breed heifers came from conventional and organic breeding. Heifers were monitored for birth date, birth weight, father's line, weight at 120 and 210 days. Significant differences (p < 0.01) were found in the evaluation of the weights of individual monitored parameters between bulls and heifers, which are confirmed by the rule that females have lower birth weight (37 kg) than males (40 kg). However, at 120 days of age, weights were higher in heifers (177 kg) compared to bulls (148 kg). In the evaluation of breeding effect, the highest (p < 0.01) weights were found in Charolais (bulls 163 kg, heifers 187 kg).

The objective of this study was to determine breed specific effects of nutritional insults during gestation on regulation of muscle and adipose tissue growth in beef cattle offspring during fetal and early postnatal development. Angus and Brahman heifers were randomly assigned to 1 of 2 dietary treatments consisting of 100% or 60% based on net energy requirements for gestating heifers. Nutritional treatments were imposed from day 50 to 180 of gestation. Fetuses harvested at 180 days of gestation had smaller frames and spared critical organs. Gene expression in several fetal tissues indicated potential for compensatory growth. Postnatally, Brahman offspring weighed less than Angus offspring and had smaller heads and heart girths along with decreased expression of growth and myogenic genes in the Longissimus dorsi. There were no differences in growth or myogenic gene expression within the Longissimus dorsi due to treatment. However, restricted animals had a decreased expression of PPARG.

No description available.

Data from 946 Angus and 351 Simmental females were used to quantify relationships between calfhood and early-life traits of females with fertility in the first two breeding seasons, and with calf production in the first, in three and in eleven years of life. These traits were used to develop prediction equations for fertility using logistic regression methodology. For productive performance, three methodologies were compared: least squares, ridge regression and principal components regression. For heifers of both breeds, fertility was associated with birth date, weaning weight ratio and weaning-yearling relative growth rate (RGR). The only calfhood trait that consistently affected fertility in the second breeding season was birth weight of the cow. Fertility of first parity Simmentals was also associated with birth-yearling RGR. First calving season traits explained a higher proportion of variation in second breeding season fertility than calfhood traits of the cow. Among these traits, calving date, calving ease score and sex of the calf were the most important. The combination of birth date and weaning-yearling RGR produced the best models to predict heifer fertility for both breeds. Fertility in the second breeding season was best predicted for Angus cows when calving date, calving ease score and sex of the calf were used as regressors. For Simmental cows, fertility in the second breeding season was best predicted from birth weight of the calf and calving ease score. The regression of weaning weight of the first calf on pre-selected calfhood traits was used to evaluate models produced by least squares, ridge regression and principal components regression. Although biased, the regression coefficient estimates produced by ridge and principal components regression had smaller variances than estimates obtained from least squares. Between the two alternatives to least squares, ridge regression produced better results than principal components regression. Ridge and least squares regression were quite similar in their regression coefficient estimates, in prediction sum of squares (PRESS)-like statistics and, to a lesser extent, in conceptual predictive criteria (C_p)-like statistics. For prediction, the performance of models produced by least squares and by ridge regression were very similar. For analyses of the production traits, least squares regression models for all possible combinations of pre-selected regressor variables were fit. Birth date of the female was negatively associated with the weaning weight of the first calf, and with number of calves weaned, total weaning weight of calves produced and average weaning weight of calves in the first three years of productive life. Age of the dam affected early-life production traits of daughters, as well as the average weaning weight of calves produced per year of productive life and calf survival in eleven years. Heavier females at birth tended to produce smaller number of calves and lower calf weaning weight through their lives than females lighter at birth. Overall female productivity was consistently more positively associated with yearling than with weaning growth traits. Among traits observed in the first calving season, calving date, calving ease score, sex and weaning weight of the calf were associated with subsequent production. Weaning weight of the first calf was always positively associated and it was the most important variable to predict female production, except for survival rate. Prediction equations for production in three years included birth date, birth weight of the female, calving ease in the first parturition, sex of the calf and weaning weight of the first calf. This latter variable was the only one useful to predict production in eleven years. Average calf weaning weights in the first three years of production were best predicted using yearling weight ratio or weaning-yearling ADG and first calf weaning weight. Models including age of the female’s dam best predicted weaning weight of calves per year of productive life in eleven years and calf survival. / Ph. D.