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Genetic parameter estimates for weaning traits in a multibreed beef cattle populationMelka, Hailu Dadi 12 1900 (has links)
Thesis (MScAgric)--University Stellenbosch, 2001. / ENGLISH ABSTRACT: The aim of this study was to estimate genetic parameters as well as to evaluate the
influence of some genetic factors on preweaning growth traits in a multi breed beef cattle
population. These preweaning growth traits were birth weight (BW), weaning weight
(WW) and average daily gain (ADG). Three aspects were addressed in this particular
study; namely the Estimation of (co)variance components and genetic parameters, the
effect of sire breeds and dam genotypes and the contribution of Charolais and Angus
breeding levels on weaning traits in a multibreed beef cattle herd.
Variance components and resulting genetic parameters of BW, WW and ADG in the
population were estimated by Restricted Maximum Likelihood (REML) procedures. Four
different unitrait and multitrait animal models were fitted ranging from a simple model
with the animal direct effects as the only random effect to the model allowing for both
genetic and permanent maternal environmental effects. The model that included directgenetic and permanent maternal environmental effects generally best described the data
analysed. The simple model ignoring maternal effects most likely inflated direct
heritability estimates. Direct heritability estimates were 0.11, 0.19, and 0.15 for BW,
WW and ADG, respectively, fitting a multitrait model that comprised of both the genetic
and maternal environmental effects. Under this comprehensive model, maternal
heritabilties were low under both analyses, ranging from 0.02 to 0.10. Permanent
maternal environmental effects were more important than maternal additive genetic
effects for WW and ADG. Direct and maternal genetic correlations range from 0.42 to
0.44 for BW, -0.22 to -0.25 for WW and -0.17 to -0.23 for ADG, while the corresponding
estimates ofunitrait analysis varied from 0.58 to 0.61 for BW, -0.43 to-0.53 for WW and
-0.49 to -0.79 for ADG.
The effect of Charolais and Hereford sires and dam breed genotypes on BW and WW in
calves of Hereford, F I, two and three breed rotational as well as terminal crosses among
the Charolais, Hereford, Angus and Bonsmara breeds were investigated. BW and WW of
the Charolais sired calves were significantly (P<O.OOl) heavier than the Hereford sired
calves. Angus dams produced calves of smaller (P<0.05) BW than those of purebred and
crossbred dams. The majority of the crossbred dams were not significantly different in
BW of calves. With regard to WW, with the exception of 3/4H1I4A, all crossbred dams
were superior (P<0.05) to Angus and Hereford dams. Calves of crossbred dams were on
the average 8% heavier at weaning than calves of purebred dams. Crossbred dams, with
intermediate Charolais contribution tend to wean heavier calves.
Data collected were also analysed to determine the optimum breeding levels of Charolais
and Angus, fitting a unitrait animal model. Further, the estimated heritabilities were
subsequently used to predict direct and maternal breeding values (Best linear unbiased
predictions) for individual animals. Best linear unbiased estimates (BLUEs) were also
calculated for the traits. BLUEs, direct and maternal breeding values per genetic group
estimated were regressed on proportions of Charolais and Angus breeding, respectively.
BLUEs of BW, WW and ADG increased with increasing the proportion of Charolais
while they decreased with increasing Angus breeding levels. In general, maternal
breeding values increased with increasing the proportions of both breeds. Direct breeding
values of Charolais increased and reached maximum values at 35, 38, and 45%
proportion of Charolais for BW, WW and ADG, respectively. No optimal Angus
proportion was found within these specific environmental conditions. In this herd it may
be suggested that increasing the proportion of Charolais to intermediate levels would tend
to improve the performances of preweaning traits. / AFRIKAANSE OPSOMMING: Die doel van die studie was om genetiese parameters in 'n meerras vleisbeeskudde te
beraam, sowel as om die invloed van sekere genetiese faktore te evalueer. Die voorspeense
groei-eienskappe het geboortegewig (BW), speengewig (WW) en gemiddelde daaglikse
toename (ADG) ingesluit. Drie aspekte is in dié betrokke studie ondersoek, naamlik; die
beraming van (ko )variansiekomponente en genetiese parameters, die invloed van ras van
vader en moedergenotipe en die invloed van Charolais en Angus bydrae op
speeneienskappe in 'n meerras vleisbeeskudde.
Variansiekomponente en afgeleide genetiese parameters vir BW, WW en ADG in die
kudde is met behulp van die Beperkte Maksimum Waarskynlikheidsprosedure (REML)
beraam. Vier verskillende enkel- en meereienskapmodelle is gepas, wat vanaf 'n
eenvoudige model wat slegs die direkte effek as enigste toevallige effek, tot dié model
waarin beide die genetiese en permanente mateme omgewingseffekte ingesluit is. Die
model wat beide die direkte en permanente mateme effekte ingesluit het, het die data die
beste gepas. Die eenvoudige model, wat die mateme effekte nie insluit nie, het in alle
waarskynlikheid die direkte oorerflikhede oorberaam. Die direkte oorerflikheidsberamingsas onderskeidlik 0.11, 0.19 en 0.15 vir BW, WW en ADG met dié meereienskapmodel
wat beide genetiese en mateme effekte ingesluit het. Met die omvattende model was die
mateme oorerflikhede laag en het van 0.02 tot 0.10 gewissel. Die permanente mateme
omgewingseffekte was belangriker as die direkte mateme effekte vir WW en ADG. Die
genetiese korrelasies tussen direkte en mateme effekte het vir BW tussen 0.42 en 0.44, vir
WW tussen -0.22 en -0.25 en vir ADG tussen -0.49 en -0.79 gewissel.
Die invloed van Charolais en Hereford bulle en moederrasgenotipes op BW en WW van
Hereford, F 1, twee- en drieras rotasie sowel as terminale kruisings tussen die Charolais,
Hereford, Angus en Bonsmara is ondersoek. BW en WW van kalwers van Charolais bulle
was betekenisvol (P<O.OOl) swaarder as kalwers van Hereford bulle. Angus koeie het
kalwers met laer (P<0.05) BW as die van ander suiwer en kruisraskoeie geproduseer.
Kalwers van die meerderheid kruisraskoeie het egter nie in BW verskil nie. Wat WW
betref, maar met die uitsondering van %HYtA, was alle kruisraskoeie beter (P<0.05) as
beide Angus en Hereford koeie. Kalwers van kruisraskoeie was gemiddeld 8 % swaarder
met speen as kalwers van suiwerraskoeie. Kruisraskoeie met intermediêre vlakke van
Charolaisbydrae het geneig om die swaarste kalwers te speen.
Die data is verder ook geanaliseer om die optimum vlakke van Charolais en Angus, deur
die passing van 'n enkeleienskap dieremodel, te bepaal. Die beraamde oorerflikhede is
vervolgens gebruik om direkte en mateme teelwaardes (Beste liniêre onsydige voospellers )
vir individuele diere te voorspel. Beste liniêre onsydige beramings (BLUE's) is ook vir
elke eienskap bereken. Die regressies van BLUE's, direkte en mateme teelwaardes per
genetiese groep bereken, is vervolgens op proporsie Charolais en Angus bydraes
onderskeidelik gepas. BLUE's vir BW, WW en ADG het met toename In
Charolaisproporsie toegeneem, terwyl dit met toename in Angusbydrae afgeneem het. In
die algemeen het mateme teelwaardes met toename in die bydrae van beide rasse
toegeneem. Direkte teelwaardes van die Charolais het toegeneem en maksimum waardes
by 35, 38 en 45 % proporsie Charolais vir onderskeidelik BW, WW en ADG bereik. Vir
die Angus is geen optimum proporsie in dié spesifieke omgewing gevind nie. In dié kudde
word intermediêre Charolais vlakke vir die verbetering van voorspeense eienskappe
aanbeveel.
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IN VITRO AND IN VIVO EVALUATION OF RECONSTITUTED SORGHUM GRAIN FOR USE IN HIGH CONCENTRATE FEEDLOT DIETS.PROUTY, FRANK LOUIS. January 1983 (has links)
Studies were conducted to: (1) examine an in situ technique with sorghum grain substrates using monofilament nylon bags, (2) evaluate in vitro various reconstituted sorghum grain treatments, (3) determine digestibility and nitrogen balance of steers fed reconstituted sorghum grain and (4) evaluate sorghum grain processing methods on performance of finishing steers. Dry matter efflux, DME (water bath) and in situ dry matter disappearance, ISDMD (ventral sac of rumen) from nylon bags were higher (P < .05) as bag porosity (5 to 80 um) and incubation time (4 to 24 h) increased, and as substrate weight: bag surface area ratio (7 to 56 mg/cm²) decreased. High linear correlations were obtained between DME and ISDMD, and also between nitrogen efflux and in situ nitrogen disapperance. No permanent influx of ruminal dry matter into nylon bags were detected. In vitro dry matter digestibility (mixed rumen inoculum) of reconstituted whole sorghum grain was influenced (P<.001) by grain moisture level (18 to 31%), constant or variable temperature during storage (-18 to 41 C) and length of storage time (3 to 28 d). All interactions of these three factors were significant (P<.05 or higher). Short term flushing with O₂, CO₂ and N₂ did not affect (P>.10) the digestibility of reconstituted whole sorghum grain. With reconstituted whole sorghum grain, grain pH could be used as a satisfactory measure of quality control. Apparent digestion coefficients for dry matter, organic matter, protein and energy were similar (P>.05) for steers fed 90% concentrate diets containing reconstituted whole or flaked sorghum grain. Nitrogen retention as a percent of nitrogen intake was 35% higher (P<.05) for steers fed reconstituted than flaked sorghum grain diets. In two finishing trials with steers, feed intake and feed conversion were higher (P<.05) for dry rolled than for flaked or reconstituted sorghum grain.
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Effects of supplementing feedlot steers and heifers with Zilpaterol hydrochloride on Warner-Bratzler Shear Force of steer longissimus lumborum and heifer longissimus lumborum, triceps brachii and gluteus medius muscles aged for 7, 14 and 21 daysClaus, Heidi L. January 1900 (has links)
Master of Science / Department of Animal Sciences and Industry / Michael E. Dikeman / The longissimus lumborum (LL) muscle from 117 steers and the LL, gluteus medius (GM), and triceps brachii (TB) from 132 heifers were obtained to evaluate the effects of feeding zilpaterol hydrochloride (Zilmax®; ZH) (7.56g/907kg on a 100% DM basis) on tenderness. Both genders were blocked by initial weight into 6 blocks of 4 pens. Pens were assigned to treatments of either 0, 20, 30 or 40 d on ZH, with a 3 d withdrawal. One steak was removed from each muscle for proximate analysis and three 2.54 cm thick steaks were vacuum aged for either 7, 14 or 21 d. Steaks were cooked to 70 ˚C and six 1.27 cm diameter cores were removed for Warner-Bratzler shear force (WBSF) determinations. All muscles from steers and heifers fed 30 and 40 d with ZH, had higher (P < 0.05) WBSF compared with controls. The WBSF of steer LL and heifer TB from the 20 d treatment was higher (P < 0.05) than controls. There were no treatment by aging interactions (P > 0.05) for WBSF of steaks from steer LL, heifer LL or heifer TB, but there was a treatment by aging interaction (P < 0.05) for WBSF of steaks from heifer GM. There were no differences (P > 0.05) in percent intramuscular fat for any muscle due to treatment. When using percent intramuscular fat as a covariate, differences in WBSF of steer LL and heifer TB were not altered, but there were slight differences in heifer LL and GM WBSF due to treatment when compared with not using percent fat as a covariate. Percentages of steaks with WBSF ≥ 5 kg increased as days on ZH increased and decreased as days of aging increased. Warner-Bratzler shear force values among the three aging times for steer LL control, 20 and 40 d treatments; all heifer LL treatments, and heifer TB 20 d were all positively correlated (P < 0.01) with each other. Feeding ZH for 20 d generally increased WBSF values, but means were still acceptable. Feeding ZH for 40 d was very detrimental to tenderness.
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The epidemiology of tetracycline and ceftiofur resistance in commensal Escherichia coliMcGowan, Matthew Thomas January 1900 (has links)
Master of Science / Department of Biomedical Science / H. Morgan Scott / The modern phenomenon of increasing prevalence of antibiotic resistance in clinically relevant bacteria threatens humanity’s ability to use antibiotics to treat infection in both humans and animals. Despite the marked complexity of bacterial evolution, there is tremendous importance in unfolding the process by which antibiotic resistance genes emerge, disperse, and persist in the natural world. This thesis investigates certain aspects of this process in two experimental studies that differ primarily by scale but also by methodology.
The first study examined the long-term annual prevalence of ceftiofur and tetracycline resistance in Canadian beef cattle from 2002 to 2011 at both phenotypic and genotypic levels. Ceftiofur was present at a very low prevalence (<4%) that did not statistically increase over the decade (p<0.05). Relative proportions of tetracycline genes tet(A), tet(B), and tet(C) also did not significantly change over the observation period. However, it was surprising that almost 20% of isolates recovered from nonselective agar harbored tet(C) given that current literature generally indicates that tet(C) is significantly less prevalent than tet(A) or tet(B). The usage of historical samples in addition to parallel selective plating using agar supplemented with antibiotics provided insight into systemic bias present in common microbial approaches. Long-term sample freezing significantly diminished the recoverability of E. coli over time. Additionally the usage of selective MacConkey agar containing tetracycline biased the proportions of tetracycline genes to over-represent the tet(B) gene in commensal E. coli compared to nonselective MacConkey agar.
The second study attempted to explain the short-term selection effects of antibiotic treatment on the overall ecological fitness of commensal E. coli using bacterial growth parameters estimated from spectrophotometric growth curves as a simple surrogate of general
fitness. Treating cattle with either tetracycline or ceftiofur was found to not only select in favor of tetracycline resistant bacteria, but also increased the overall fitness among the tetracycline resistant population. However, growth curves were unable able to explain why transiently selected resistant bacteria were eventually replaced by susceptible bacteria once the selection pressure was removed.
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Modelos de análise de dados de provas de ganho em peso de bovinos da raça Nelore /Oliveira Junior, Braz Costa de. January 2009 (has links)
Resumo: dados de prova de ganho em peso (PGP) em confinamento, visando aumento na resposta à seleção pela inclusão de informações de parentesco nas estimativas dos parâmetros genéticos, assim como na acurácia dos valores genéticos estimados e na classificação final dos animais. As características analisadas foram o peso ao final da PGP (P378), o ganho em peso após o período de adaptação (G112), um índice considerando P378 e G112 (IPGP), além do peso inicial e dois pesos intermediários. Foram utilizadas 18.825 mensurações de pesos de 4.758 animais. Os modelos de dimensão finita considerados incluíram os efeitos fixos de mês e ano de nascimento (1977 a 2006) e classe de idade da mãe ao parto (2 a ≥12 anos), além do efeito linear da idade do animal no início da PGP como covariável. Quanto aos efeitos genéticos, foram considerados dois modelos, um só com o efeito genético direto e outro incluindo o efeito de ambiente permanente materno. Os modelos de regressão aleatória incluíram, como aleatórios, os efeitos genéticos aditivos direto, de ambiente permanente direto e materno e, como fixos, os efeitos de grupo de contemporâneos, a classe de idade da vaca ao parto e o polinômio ortogonal de Legendre da idade do animal (regressão quadrática), como covariáveis. Para comparar os resultados obtidos pelos modelos de regressão aleatória, foram conduzidas análises multicaracterísticas. Um total de 13 modelos de regressão aleatória, aplicando polinômios de segunda a quinta ordem foram considerados para modelar os efeitos genéticos aditivos direto e de ambiente permanente direto e materno. O resíduo foi modelado considerando 1, 3, 4, 6 e 9 classes de variâncias. O modelo contendo 4 classes de variâncias foi o que melhor descreveu o comportamento da trajetória para o efeito... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work was carried through with the objective of study different analysis forms of datasets regarding weight gain test (PGP) in feedlot, aiming improve in selection response through the inclusion of kinship information on estimates of genetic parameters, as well as in the estimated breeding values accuracy and in the final classification of the animals. We analyzed the characteristics weight at the end of PGP (P378), the weight gain after adaptation period (G112), an index considering P378 and G112 (IPGP), as well as the initial weight and two intermediate weights. 18,825 records of weights from 4.758 animals had been used. The considered models of finite dimension had included the fixed effects of year of birth (1977 to 2006) and cow age at birth class (2 ≥12 years), as well as the linear effect of the age of the animal at the PGP beginning as covariate. In spite the genetic analyses, we considered two models: one only with the direct genetic effect and another one including the maternal permanent environment effect. The random regression models included, as random, the additive direct genetic effect, the permanent direct and maternal environment effect, and, as fixed effects, the contemporary group, age of cow at birth class and the Legendre orthogonal polynomial of the animal age (quadratic regression), as covariates. In order to compare the achieved results for the models of random regression, we precede multicharacteristic analysis. A total of 15 models of random regression, applying polynomials of second to fifth order had been considered to fit the additive direct genetic effect and direct and maternal permanent environment effects. The residual was fitted considering 1, 3, 4, 6 and 9 variance classes. The model containing 4 variance classes was the ones that better described the trajectory... (Complete abstract click electronic access below) / Orientadora: Lúcia Galvão de Albuquerque / Coorientadora: Maria Eugênia Zerlotti Mercadante / Banca: Danísio Prado Munari / Banca: Lenira El Faro Zadra / Mestre
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Estimação dos parâmetros genéticos do peso adulto em matrizes da raça Nelore / Genetic parameters estimation for mature weight in Nelore beef cattlePedrosa, Victor Breno 07 December 2006 (has links)
O estudo das características produtivas visa a obtenção de animais possuidores de genótipos com potencial para altas produções mas que sejam também adaptados ao meio ambiente de criação extensiva no Brasil. Esses animais produtivos e adaptados poderiam otimizar os custos, tornando assim, sua criação sustentável em escala comercial. Apesar das características reprodutivas serem de extrema importância como objetivo de seleção, sua utilização não tem sido ampla em programas de melhoramento genético por serem consideradas de baixa herdabilidade. Entre as características produtivas existentes em bovinos de corte pode ser citada a caracterítica de peso adulto, que deve ser avaliado e monitorado o aumento do tamanho das fêmeas pela resposta indireta a seleção para peso, afim de confrontar os resultados economicamente. Dentro deste contexto foram avaliados dados de 74.547 animais com o objetivo de analisar o peso adulto e o peso adulto com repetibilidade (PAVr) em animais Nelore estimando a herdabilidade de características de desenvolvimento ponderal, utilizando modelos lineares; Estimar a correlação entre peso adulto (PAV) e características de peso ao sobreano (PS), conformação (CONF), precocidade (PREC), musculosidade (MUSC) e altura de garupa (AG); Determinar se há ou não vantagem em incluir o peso adulto em programas de seleção na raça Nelore. Os componentes de variância e de covariância foram estimados pelo método de máxima verossimilhança restrita (MTDFREML) utilizando-se o modelo animal. As estimativas dos coeficientes de herdabilidade foram de 0,43 para PAV e 0,41 para PAVr; 0,38 para PS; 0,23 para CONF; 0,19 para PREC; 0,22 para MUSC e 0,35 para AG. Os coeficientes de correlação genética obtidos variaram de 0,37 a 0,97. Os resultados sugerem que ganhos genéticos podem ser obtidos com a seleção para a característica de peso adulto, em monitoramento do tamanho de fêmeas na raça Nelore. A correlação entre as característica em estudo demonstra haver uma tendência de alteração das características de tamanho a partir da seleção para peso adulto. / The study of the productive traits aims the obtention of animals that have genotypes with potencial for high productions but that are also adaptable to the environment of the extensive creation in Brazil. These productive and adaptable animals could improve the costs, making therefore, their creation sustainable on a commercial scale. Although the reproductive characteristics have an extremely importance as an objective of the selection, its utilization have not been ample in genetic improvement programs for being considered as a low heritability trait. Between the productive traits existent in beef cattle it can be cited the mature weight trait, that must be evaluated and monitorated for the size increase control of the females by the indirect answer to weight selection, in order to confront, economically, the results. In this context it was evaluated data from 74.547 animals with the objective of analyze the mature weight and the adult weight with repeated measurements (MWr) in Nelore animals estimating the heritability of the ponderal development traits, using linear models; Estimate the correlation between mature weight (MW) and the post-weaning weight trait (PW), conformation (CONF), precocity (PREC), musculature (MUSC) and hip height (HH); Determine if there is an advantage in the inclusion of the mature weight in selection programs of the Nelore breed. The components of variance and covariance were estimated by the method of Restricted Maximum Likelihood Multiple Trait Derivative Free (MTDFREML) using the animal model. The estimation of the heritability coefficients were 0,43 for MW and 0,41 for MWr; 0,38 for PW; 0,23 for CONF; 0,19 for PREC; 0,22 for MUSC and 0,35 for HH. The genetic correlation coefficients varied from 0,37 to 0,97. The results suggest that genetic gains can be obtained with the selection for the mature weight characteristic, with the monitoration of the female sizes for Nelore breed. The correlation between the characteristics in study shows that there is a tendency for alteration in size characteristics through the selection for mature weight.
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Estratégias de imputação de genótipos de marcadores SNP para estudos de associação genômica em animais da raça Nelore / Strategies of genotypes imputation for genome-wide association studies in Nellore cattleSilva, Fabiane de Lima 07 November 2013 (has links)
Temperamento em bovinos é definido como a reação dos animais em resposta ao contato com o ser humano, geralmente atribuído ao medo ocasionado no manejo. Animais agitados são mais difíceis de manejar nas fazendas. Estudos na literatura mostram que características de temperamento influenciam o desempenho produtivo dos rebanhos, devido à sua correlação com outras características dentre elas, ganho de peso diário, taxa de prenhez, qualidade e rendimento de carcaça. Todavia, estudos visando o melhor entendimento dos mecanismos biológicos, e da arquitetura genética destas características são escassos. Com a evolução das tecnologias de genotipagem em alta densidade com marcadores de polimorfismo único (SNP), observou-se um aumento de pesquisas nas áreas de seleção genômica (GS) e associação genômica (GWAS). Entretanto, devido ao alto custo que a genotipagem em larga escala apresenta, torna-se inviável a genotipagem para todos os animais candidatos à seleção. Porém, existe a possibilidade de utilizar painéis de baixa densidade de SNP e inferir estes genótipos desconhecidos para painéis de alta densidade. Neste contexto foram desenvolvidos dois estudos. No primeiro, o objetivo foi identificar regiões cromossômicas associadas com características de temperamento em animais da raça Nelore. As características avaliadas foram: velocidade de saída (VS) e mediana do escore composto (EC_mediana), em que 599 e 575 animais foram utilizados, respectivamente. Todos os animais foram genotipados com Illumina BovineHD BeadChip (800K), e para o GWAS dois modelos estatísticos foram aplicados. O primeiro modelo utilizado foi genômico de única etapa (ssGBLUP), em que os efeitos dos SNP são derivados da predição dos valores genéticos genômicos dos animais. O segundo modelo foi linear misto, similar ao modelo anterior, porém várias análises, SNP por SNP (regressão simples) foram realizadas. Nos dois modelos foram incluídos os efeitos de grupo de contemporâneo como fixo, idade do animal como covariável e efeito poligênico do animal e ambiente permanente como aleatórios. Os componentes de variância foram estimados pelo método de máxima verossimilhança restrita. Os coeficientes de herdabilidade apresentaram baixa magnitude com estimativas de 0,02 e 0,05 para VS e EC_mediana, respectivamente. Diferentes regiões cromossômicas foram associados com as características estudadas nesta população, de acordo com os modelos utilizados, contribuindo para o entendimento da arquitetura genética dessas características. No segundo, o objetivo foi avaliar a acurácia de imputação também nesta população, usando dois painéis de baixa densidade (3K e 6K) e um de média densidade (50K) imputados para o painel de alta densidade (800K). Os animais genotipados com 800K foram divididos em população de validação e população de referência. Na população de validação, os animais tiveram seus genótipos mascarados para os chips Illumina 3K, 6K e 50K. A imputação de 3K, 6K e 50K para 800K foi realizada utilizando os softwares de imputação fastPHASE e Beagle. O software fastPHASE apresentou maiores valores de acurácia de imputação em comparação ao Beagle. O painéis 6K e 50K apresentaram maiores valores de acurácia. / Temperament in cattle is generally defined as the reaction of an animal in response to contact with human, usually attributed to the fear. Animals agitated are harder to manage in farms. Studies in the literature reported that temperamental traits have been found to influence the productive performance of herds, due to its correlation with other traits such as carcass quality, daily gains, pregnancy rate and feed efficiency. However, almost nothing is known regarding the genetic landscape controlling temperamental animal variation in cattle. With the advances in genotyping technologies for high density genotyping platforms to markers of single nucleotide polymorphisms (SNP), there was an increase in research in the areas of genomic selection (GS) and genome-wide association studies (GWAS). However, genotyping many animals with a high-density marker panel can be expensive and economically unfeasible. An alternative in this context is to use a lower density marker panel on a larger number of animals, and impute the missing genotypes. In this context two studies were developed. In the first study, the objective was to identify chromosomal regions associated with temperament traits in Nellore cattle. The temperamental traits evaluated in this study were: exit velocity (VS) and the median score temperament (EC_mediana) assessed in 599 and 575 animals, respectively. All animals were genotyped with Illumina BeadChip BovineHD (800K), and two GWAS statistical models were applied. The first model used was genomic single step (ssGBLUP) in which the effects of SNP are derived from the genomic prediction values of the animals. The second was linear mixed model, similar to the previous model, but a series of models, one for each SNP (single regression), were performed. In both models were included the effects of contemporary group as fixed, the animal\'s age as a covariate effect and polygenic animal and permanent environment as random effect. Variance components were estimated by restricted maximum likelihood. The heritability coefficients showed low magnitude estimative of 0.02 and 0.05 for VS and EC_mediana, respectively. Different chromosomal regions were associated with the traits studied in this population, according with the models used, and moreover to contribute in the understanding of the genetic architecture of these traits. In the second study, the objective was to evaluate the accuracy of imputation in a same population, using two panels of low-density (3K and 6K) and one medium-density (50K) panel markers imputed up to higher density of 800K. The animals genotyped with 800K markers panel were split into a reference population and validation population. The validation population the animals had markers masked to Illumina chip 3K, 6K e 50K. Imputation from 3K, 6K and 50K up to 770K markers was performed using fastPHASE and Beagle. The software fastPHASE had higher imputation accuracy compared to Beagle. The 6K and 50K panels showed higher accuracy.
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Avaliação da reutilização de implantes contendo progestágenos para controle farmacológico do ciclo estral e ovulação em vacas de corte. / Evaluation of progestagen implants reutilization on pharmacological control of estrus cycle and ovulation in beef cows.Maluf, Décio Zuliani 15 July 2002 (has links)
Duzentos e vinte e uma vacas (78 com bezerros entre 40 e 90 dias de idade) mestiças Nelore (Bos taurus indicus) X Charolês (Bos taurus taurus) foram utilizadas para avaliar a reutilização de implantes auriculares de silicone impregnados com progestágenos para controle farmacológico do ciclo estral e ovulação. Os tratamentos experimentais consistiram de três protocolos para sincroni zação do cio e inseminação artificial em tempo pré-determinado. No tratamento 1 (T1; n=73) as vacas receberam um implante auricular de Crestar® (3 mg de norgestomet); no tratamento 2 (T2; n= 75) as vacas receberam um implante auricular de Crestar® já utili zado anteriormente em outra sincronização; e no tratamento 3 (T3; n=73) as vacas receberam dois implantes auriculares de Crestar® também já utilizados, os quais foram colocados lado a lado na mesma orelha. Além dos implantes, as vacas receberam aplicação intramuscular (im) de uma associação de 2 mL de progesterona (25mg/mL) + benzoato de estradiol (1mg/mL) no momento da colocação dos implantes (D0). Os implantes foram removidos após 8 dias (D7) junto a uma aplicação (im) de Preloban® (150mg de D-cloprostenol). Após 24h da remoção do implante, foi aplicado uma dose (im) de Estrogin® (1mg de benzoato de estradiol). Todas as vacas foram inseminadas artificialmente 54-56h após a retirada dos implantes. Noventa por cento do sêmen utilizado no experimento foi proveniente de um só touro, os 10% restantes foram distribuídos equitativamente entre os tratamentos. A inseminação artificial foi realizada por um único inseminador. As vacas com bezerro ao pé apresentaram um escore de condição corporal entre 5 e 6, numa escala de 1 a 9, e as vacas sem bezerro entre 6 e 7. A variável estudada foi a taxa de prenhez das vacas. A análise estatística foi realizada com o auxílio do pacote estatístico "Statistical Analysis System 8.0", utilizando regressão logística. Não houve dife rença na taxa de prenhez das vacas, sendo 39,72%, 34,21% e 36,98% para os tratamentos T1, T2 e T3, respectivamente. A reutilização de implantes com progestágeno não altera a taxa de prenhez de vacas aptas à reprodução. / Two-hundred and twenty-one (78 suckling- 40 to 90 days) Nelore (Bos taurus indicus) X Charolais (Bos taurus taurus) cows were used to evaluate the reutilization of progestagen implants to control pharmacologically the estrus cycle and ovulation. Cows were randomly assigned to one of three protocols for estrous synchronization and artificial insemination in pre-fixed time. In treatment 1 (T1; n=73) cows were implanted with Crestar® (3 mg de norgestomet); in treatment 2 (T2; n= 75) cows were implanted with Crestar®, already used in a previous synchronization; and in treatment 3 (T3; n=73) cows received two Crestar® implants, also previously used, both placed side by side in the same ear. All cows were injected with an intra muscular (i.m.) dose of 2 mL of progesterone (25mg/mL) + estradiol benzoate (1mg/mL) at the time of implants insertion (D0). Implants were removed after 8 days (D7) and an i.m. dose of Preloban® (150mg de D-cloprostenol) was administered. Twenty-four hours after implants removal, cows were i.m. injected with a dose of Estrogin® (1mg of estradiol benzoate). All cows were artificially inseminated at 54-56 h after implants removal. Ninety percent of semen used in the experiment was from only one bull, the remaining 10% were equally distributed among treatments. Artificial insemination was performed by only one technician. Suckling cows had a body condition score of 5-6, in a scale of 1-9, and the non-suckling cows were 6-7. Pregnancy rate was the variable studied. Statistical analysis was accomplished by using "Statistical Analysis System 8.0", and logistic regression. There was no difference (P>0.05) on cows pregnancy rate among treatments. Pregnancy rates were 39.72, 34.21 and 36.98% for T1, T2 and T3, respectively. Progestagen implants reutilization did not affected pregnancy rate in beef cows ready for reproduction.
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Validação de método e triagem de cádmio no sistema de produção de carne em pasto / Method validation and screening of cadmium on beef cattle pastures productionLima, Janaina Rosolem 20 June 2011 (has links)
Os contaminantes inorgânicos, entre eles o cádmio (Cd), estão associados a efeitos negativos na saúde humana e animal. Este projeto, em parceria com o Ministério da Agricultura, Pecuária e Abastecimento, foi desenvolvido com o objetivo de validar método analítico para determinação de Cd em matriz de alface para extensão de aplicabilidade em outras matrizes vegetais. A otimização e validação foram realizadas no Lanagro-SP em Campinas, sendo testadas as técnicas de digestão via seca, digestão via úmida em forno micro-ondas e suspensão ácida. A suspensão ácida propiciou melhores recuperações (70 a 110%), maior simplicidade de preparo e economia de reagentes, logo foi a técnica selecionada para validação. O método consiste em pesagem de 0,5 g de alface moído, adição de 2,5 mL de ácido nítrico, sonicação durante 20 minutos, tempo de reação de 2 horas e 20 minutos de centrifugação. As análises estatísticas consistiram em cálculo da média aritmética e coeficiente de variação entre replicatas de amostras. Para validação do método foram avaliados os seguintes parâmetros: sensibilidade, linearidade, precisão e exatidão com material de referência certificado, recuperação, seletividade ou efeito matriz, limite de detecção e quantificação, repetitividade e reprodutibilidade. Todos os experimentos da validação realizados até o momento estão de acordo com o requerido pelo Regulamento (CE) 657/2002 e INMETRO. As análises estatísticas consistiram basicamente em avaliação da média aritmética, desvio-padrão e coeficiente de variação. Após validação, o método foi utilizado para estudo de caso com amostras provenientes de experimento conduzido na USP/ESALQ Piracicaba com 63 bovinos de corte desmamados ½ Nelore x ½ Canchim em B. brizantha sob lotação rotacionada, com terminação em confinamento. O delineamento foi em blocos completos casualizados com três tratamentos e três repetições: T1 sal mineral ad libitum; T2 sal mineral + milho (0,3% do peso vivo PV); T3 sal mineral + milho (0,6% até 0,9% PV). Foram amostrados pasto, feno (Tifton 85), milho, sorgo, farelo de soja, solo, água, rins e fígado. As amostras vegetais foram preparadas pela técnica de suspensão ácida e os tecidos por calcinação, todos analisados por espectrometria de absorção atômica com forno de grafite (GF AAS). Na triagem algumas amostras estiveram abaixo do limite de quantificação (LQ) dentre elas a pastagem (13 µg kg-1), farelo de soja e milho (8 µg kg-1) e água (0,0025 mg L-1), ao passo que feno e sorgo permaneceram acima do L.Q. porém abaixo do limite máximo permitido (200 µg kg-1). O solo com pH ácido de 5,4 com 1,5 mg kg-1 de Cd. As amostras de fígado apresentaram teor abaixo do LQ (22 µg kg-1) e as de rim abaixo do máximo permitido (1000 µg kg-1). Não houve diferença entre tratamentos. Utilizou-se estatística descritiva para amostras vegetais e transformação logarítmica (10) nos dados de rim pelo SAS com médias comparadas pelo teste t a 5%. Não foram encontrados teores prejudiciais de Cd neste estudo. / The inorganic contaminants like cadmium (Cd) are toxic to human and animal health. This work, accomplished with Ministry of Agriculture, Livestock and Food Supply, had the purpose to validate an analytical method for Cd determination in lettuce samples and other vegetables samples. The development and validating steps were made on Lanagro-SP in Campinas. The techniques tested were dry ashing, microwave digestion and slurry. The slurry method had best recoveries (70 % up to 110%), the simplest preparing with less reagents, so it was selected to be validate. After optimizing the experimental parameters, the steps of the method were the following: weighting 0.5 g of ground lettuce; addition of 2.5 mL of HNO3 distilled; 20 minutes of sonication; 2 hours of standing and 20 minutes of centrifugation after volume completed for 25 mL. The statistical analyses were did evaluating means and relative standard deviation of the experiments. To validate the method the sensibility, linearity, precision and accuracy with certified reference material, recovery, matrix effects, limit of detection, limit of quantification, repeatability and reproducibility. All the experiments that have been done until now are in accordance with Comission Decision (CD) 2002/657/EC and INMETRO. The statistical analyses were basic the same at the development period. After the validation, the method was used in a screening with samples from ESALQ/USP Piracicaba experiment using 63 ½ Nelore x ½ Canchim beef steers, under a rotational grazing system in B. brizantha, finishing animals in feedlot. The experimental design was a randomized block with three treatments and three replications: T1 - mineral supplementation (MS) ad libitum; T2 - MS + corn (0.3% body weight BW); T3 - MS + corn (0.6% up to 0.9% BW). Samples of pasture, hay (Tifton 85), corn, sorghum, soybean meal, soil, water, kidney and liver were collected. Vegetables samples were prepared by acid slurry and animal tissues by dry ashing, and then all analyzed by graphite furnace atomic absorption spectrometry (GF AAS). Some samples were under limit of quantification (LOQ) like pasture (13 µg kg-1), soybean meal and corn (8 µg kg-1) and water (0.0025 mg L-1), while hay and sorghum were bellow acceptable levels (200 µg kg-1). Soil pH was 5.4 with a Cd content of 1.5 mg kg-1. The liver samples were under LOQ (22 µg kg-1) and kidney samples were bellow acceptable levels (1000 µg kg-1, FB).There was no difference between treatments. The vegetables data were submitted to descriptive statistics, while kidney means were transformed by log (10) on SAS and compared by t test in 5% level. No hazardous Cd concentrations were observed in this trial.
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Produtividade e viabilidade econômica da recria e engorda de bovinos em pastagens adubadas intensivamente com e sem o uso da irrigação. / Productivity and economic viability of beef cattle production at highly fertilazed pastures with and without irrigation.Maya, Fabio Luiz Aires 04 July 2003 (has links)
A pecuária de corte extensiva se mostra incapaz de competir em termos de resultados econômicos com outras alternativas de uso da terra em regiões de terras valorizadas, fato que pode ser comprovado pela substituição gradativa de áreas de pastagens por culturas agrícolas. Nessas regiões, a adubação intensiva de pastagens tem se tornado a opção freqüentemente utilizada para o incremento da produtividade animal que é imprescindível para a viabilização econômica da pecuária frente a demais alternativas de uso da terra. A irrigação aliada à adubação de pastagens cresceu muito desde o final da década de 90 no Brasil Central, crescimento motivado pela expectativa de resultados produtivos elevados como os divulgados por revistas técnicas especializadas. Com o intuito de comparar os resultados produtivos e econômicos de pastagens adubadas intensivamente com e sem o uso da irrigação, foram conduzidos dois experimentos ao longo de um ano em pastagens de Panicum maximum cv tanzânia. Foram avaliados desempenho animal, taxa de lotação e produtividade nos experimentos. A avaliação econômica foi efetuada com a determinação dos indicadores lucro líquido, taxa de retorno sobre o ativo e taxa interna de retorno, por meio de simulações determinísticas e estocásticas. Enquanto no experimento em sequeiro os valores de desempenho animal e de taxa de lotação médios obtidos foram de 0,615 kg GPD e 5,6 UA/ha, respectivamente, no experimento irrigado foram obtidos 0,492 kg GPD e 5,9 UA/ha. A irrigação só foi efetiva no incremento da taxa de lotação na transição entre os períodos de "seca" e "águas", não confirmando o potencial da irrigação de pastagens no incremento da taxa de lotação. A diferença de produtividade animal entre os experimentos foi minimizada pelo maior desempenho animal do experimento sem irrigação em alguns períodos. Foram obtidas produtividades de 1.628 kg PV/ha no experimento irrigado e 1.672 kg PV/ha no em sequeiro, corroborando o potencial de produtividade de pastagens adubadas intensivamente. A análise de viabilidade sem a consideração de risco apresentou resultados de lucro líquido, taxa de retorno sobre o ativo e taxa interna de retorno, respectivamente de R$ - 164,91 por hectare, - 1,0% e - 6,1%, para o sistema irrigado e R$ 574,90 por hectare, 4,4% e 17,2% para o em sequeiro. Contudo, essa análise subestimou os resultados dos indicadores de viabilidade econômica em ambos sistemas. A análise de risco apontou o sistema irrigado como inviável economicamente, enquanto para o sistema sem irrigação a probabilidade de um resultado econômico que apontasse inviabilidade foi baixa. / Extensive beef production cannot compete with others uses of land for agricultural productions, mainly where land costs are high, therefore a gradual substitution of pasture areas for agricultural crops is occurring. High levels of fertilizer application to pastures have been used for improving beef productivity and, consequently, improve the economic profitability of this activity. Irrigation of pasture increased since 90s in Central Brazil, motivated by the expectation of high productivities as presented in technical magazines. The objective of this research was to compare the productivity and economic results of highly fertilized pasture, with and without irrigation. Two experiments were conducted for a year in Panicum maximum cv tanzânia pastures. Weight gain, stocking rate and beef productivity were evaluated. In the economic evaluation was determined net margin, simple rate of return and internal rate of return, using deterministic and stochastic simulations. In the non-irrigated experiment the weight gain was 0,615 kg/day and the stocking rate 5,6 AU/ha, and in the irrigated one, 0,492 kg/day and 5,9 AU/ha, respectively. The irrigation only increased the stocking rate in the season transition between dry and rainy period, not confirming the potential for pasture irrigation in the Central South part of Brazil by increasing stocking rate. Productivity difference in irrigated and non-irrigated pastures was minimized by the high weight gain of non-irrigated area in some periods. The animal live weigh gain was 1.628 kg/ha in irrigated experiment, and 1.678 kg/ha in non-irrigated one, indicating high potential for productivity of highly fertilized pasture. The analysis without risk consideration showed results of net margin, simple rate of return and internal rate of return, respectively of R$ -164,91 per hectare, - 1,0% and -6,1% for irrigated system, and R$ 574,90 per hectare, 4,4% and 17,2% for non-irrigated one. Deterministic analysis sub estimated the results of economic viability indicators. Risk analysis showed weak probability of economic viability for irrigated system. Non-irrigated system with high levels of fertilizer application indicated weak probability for not been an economic activity.
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