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Efeito de níveis crescentes de uréia na dieta de vacas em lactação sobre produção, composição e qualidade do leite; Effects of dietary urea levels for dairy cows on milk yield, composition and quality

Aquino, Adriana Augusto
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/02/2006 PT
Relevância na Pesquisa
66.5%
Este estudo teve como objetivo avaliar o efeito de níveis crescentes de uréia na dieta de vacas em lactação sobre a produtividade, características físico-químicas e de composição do leite, bem como composição da proteína do leite. Foram utilizadas nove vacas Holandesas em lactação, em delineamento experimental tipo quadrado latino 3X3, com 3 tratamentos, 3 períodos e 3 quadrados. O experimento teve duração total de 63 dias divididos em 3 períodos de 21 dias. Os tratamentos foram: tratamento A (controle) com dieta formulada para suprir 100% das exigências do NRC (2001) em termos de PB, proteína degradável no rúmen (PDR), proteína não degradável no rúmen (PNDR), utilizando farelo de soja como principal fonte protéica e cana-de-açúcar como volumoso; tratamento B, dieta com a inclusão de 0,75% de uréia, em substituição parcial ao farelo de soja, e tratamento C, dieta com inclusão de 1,5% de uréia, em substituição parcial ao farelo de soja. Todas as dietas foram isoenergéticas (1,53 Mcal/kg de energia líquida de lactação) e isoprotéicas (16% de proteína bruta). Não foram observadas diferenças entre os tratamentos, quando os resultados foram analisados por regressão polinomial simples, quanto a: consumo de matéria seca...

Produção e composição do leite de vacas com mastite subclínica causada por Staphylococcus coagulase negativa; Milk yield and composition of cows with subclinical mastitis caused by coagulase negative staphylococci

Tomazi, Tiago
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/06/2013 PT
Relevância na Pesquisa
66.54%
Staphylococcus coagulase negativa formam o grupo de agentes mais isolados de vacas com mastite em diversos países. No entanto, a grande variedade de espécies e a ausência de métodos de identificação simples e rápidos são fatores que limitam a avaliação do efeito da mastite causada por SCN sobre a produção e composição do leite. Portanto, os objetivos gerais deste estudo foram: 1) avaliar o efeito da infecção intramamária (IIM) subclínica causada por SCN sobre a composição e a produção de leite de quartos mamários; 2) determinar o efeito da IIM causada por SCN sobre a composição do leite e contagem de células somáticas (CCS); 3) avaliar a técnica de espectrometria de massas por ionização e dessorção a laser assistida por matriz tempo de voo (MALDI-TOF MS) para a identificação das espécies de SCN isoladas de vacas com mastite; 4) avaliar a frequência de espécies de SCN isoladas de vacas com mastite subclínica. Amostras compostas de leite foram coletadas de 1.242 vacas pertencentes a 21 rebanhos leiteiros. As coletas foram realizadas em duas etapas: na primeira, realizou-se coleta asséptica de amostras compostas para identificação dos agentes causadores de mastite; e na segunda, para as vacas com isolamento de SCN...

Farelo de algodão e grão de soja integral em dietas com de cana-de-açúcar para vacas leiteiras: consumo, digestibilidade, produção e composição do leite; Cottonseed meal and whole soybean seed in diets with sugar cane for dairy cows: intake, digestibility, milk yield and composition

Migliano, Marina Elena Diniz Amaral
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/06/2013 PT
Relevância na Pesquisa
66.37%
O objetivo do estudo foi avaliar o efeito de dois teores de proteína bruta (PB) e duas fontes nitrogenadas principais na dieta de vacas leiteiras, utilizando cana-de-açúcar como volumoso, sobre o consumo, a digestibilidade aparente, produção e a composição do leite. Foram utilizadas 12 vacas Holandesas em estágio intermediário de lactação, agrupadas em três quadrados latinos 4x4 contemporâneos, com período experimental de 21 dias, sendo 14 para adaptação às dietas e os sete últimos para coletas. As vacas foram alojadas em baias individuais e alimentadas "ad libitum" com 4 dietas com duas fontes nitrogenadas principais (farelo de algodão 38 e grão de soja cru integral) e dois teores de PB (130g e 148g/Kg de MS) na dieta. As amostras de leite para análise da composição foram coletadas do 14º ao 17º dia de cada período. A digestibilidade foi determinada por meio de indicador interno FDAi. O consumo de FDN e EE foi maior para vacas alimentadas com grão de soja que para as vacas alimentadas com farelo e algodão. O consumo de extrato etéreo (EE) foi maior para vacas alimentadas com dietas com 148g PB/Kg de MS. Por outro lado, vacas alimentadas com dietas contendo farelo de algodão, apresentaram maior consumo de matéria orgânica do que para vacas alimentadas com grão de soja. Houve interação entre fonte nitrogenada e teor de PB da dieta sobre CMS...

Estimates of correction factors for lactation length and genetic parameters for milk yield in buffaloes

Tonhati, Humberto; Muñoz, M.F.C.; Duarte, J.M.C.; Reichert, R.H.; Oliveira, J.A.; Lima, A.L.F.
Fonte: Universidade Federal de Minas Gerais (UFMG), Escola de Veterinária Publicador: Universidade Federal de Minas Gerais (UFMG), Escola de Veterinária
Tipo: Artigo de Revista Científica Formato: 251-257
ENG
Relevância na Pesquisa
66.47%
Estimaram-se fatores de correção para produção de leite aos 90, 240, 270 e 305 dias de lactação e parâmetros genéticos e de ambiente da produção de leite ajustada para esses períodos de lactação, utilizando-se 3888 lactações de 1630 búfalas, controladas entre 1987 e 2001, em 10 rebanhos do Estado de São Paulo. Os parâmetros genéticos foram estimados por meio do método da máxima verossimilhança restrita, livre de derivadas, aplicado a um modelo animal com medidas repetidas. As estimativas de herdabilidade para produção de leite corrigida para 90, 240, 270 e 305 dias de lactação foram 0,17; 0,15; 0,14 e 0,14, respectivamente. Nessa mesma ordem de apresentação, as estimativas de repetibilidade foram 0,40; 0,44; 0,41 e 0,41. As estimativas de correlação genética entre essas produções de leite corrigidas variaram de 0,96 a 1,00. Os fatores de correção multiplicativos para as diferentes classes de duração da lactação foram eficientes para ajustar a produção de leite aos 90, 240, 270 e 305 dias de lactação.; Correction factors for milk yield at 90, 240, 270 and 305 days of lactation of buffaloes and genetic and environmental parameters for milk yield of these lactation periods were estimated. The data used consisted of 3888 lactation records of 1630 buffaloes from 10 herds reared in the State of São Paulo. Genetic parameters were estimated by the derivative free restricted maximum likelihood method...

Population structure and effects of inbreeding on milk yield and quality of Murrah buffaloes

Santana, M. L.; Aspilcueta-Borquis, R. R.; Bignardi, A. B.; Albuquerque, Lucia Galvão de; Tonhati, Humberto
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 5204-5211
ENG
Relevância na Pesquisa
66.31%
To provide data for conservation, selection, and expansion programs of buffalo herds, this study evaluated the history of a population of Murrah buffaloes based on population structure and the effect of inbreeding on accumulated 305-d milk yield (MY), fat yield (FY), protein yield (PY), mozzarella production (MProd), and somatic cell score (SCS). The usefulness of including the individual inbreeding coefficient (F) or individual increase in inbreeding coefficient (Delta F) in the model to describe inbreeding depression was evaluated. Pedigree information from 8,054 animals born between 1976 and 2008 and 4,497 lactation records obtained from 12 herds were used. The realized effective population size was 40.10 +/- 1.27, and the mean F of the entire population was 2.14%. The ratio between the number of founders and ancestors demonstrated the existence of a bottleneck in the pedigree of this population, which may contribute to a reduction of genetic diversity. The effect of F on MY, FY, PY, MProd, and SCS was -1.005 kg, -0.299 kg, -0.246 kg, -1.201 kg, and -0.002 units, and the effect of Delta F transformed to equivalent F (%) for a mean of 2.57 equivalent generations was -4.287 kg, -0.581 kg, -0.383 kg, -2.001 kg, and -0.007 units, respectively. The inbreeding depression observed may have important economic repercussions for production systems. The Delta F can be considered the better of the two indicators of inbreeding depression due to its properties that prevent underestimation of this effect. A designed mating system to avoid inbreeding may be applied to this population to maintain genetic diversity.

Estimation of genetic parameters for milk yield in Murrah buffaloes by Bayesian inference

Breda, F. C.; Albuquerque, Lucia Galvão de; Euclydes, R. F.; Bignardi, A. B.; Baldi, Fernando; Torres, R. A.; Barbosa, L.; Tonhati, Humberto
Fonte: Amer Dairy Science Assoc-adsa Publicador: Amer Dairy Science Assoc-adsa
Tipo: Artigo de Revista Científica Formato: 784-791
ENG
Relevância na Pesquisa
66.29%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Random regression models were used to estimate genetic parameters for test-day milk yield in Murrah buffaloes using Bayesian inference. Data comprised 17,935 test-day milk records from 1,433 buffaloes. Twelve models were tested using different combinations of third-, fourth-, fifth-, sixth-, and seventh-order orthogonal polynomials of weeks of lactation for additive genetic and permanent environmental effects. All models included the fixed effects of contemporary group, number of daily milkings and age of cow at calving as covariate (linear and quadratic effect). In addition, residual variances were considered to be heterogeneous with 6 classes of variance. Models were selected based on the residual mean square error, weighted average of residual variance estimates, and estimates of variance components, heritabilities, correlations, eigenvalues, and eigenfunctions. Results indicated that changes in the order of fit for additive genetic and permanent environmental random effects influenced the estimation of genetic parameters. Heritability estimates ranged from 0.19 to 0.31. Genetic correlation estimates were close to unity between adjacent test-day records, but decreased gradually as the interval between test-days increased. Results from mean squared error and weighted averages of residual variance estimates suggested that a model considering sixth- and seventh-order Legendre polynomials for additive and permanent environmental effects...

Genetic parameters of total milk yield and factors describing the shape of lactation curve in dairy buffaloes

Aspilcueta-Borquis, Rusbel R.; Baldi, Fernando; Araujo Neto, Francisco R.; Albuquerque, Lucia Galvão de; Munoz-Berrocal, Milthon; Tonhati, Humberto
Fonte: Cambridge University Press Publicador: Cambridge University Press
Tipo: Artigo de Revista Científica Formato: 60-65
ENG
Relevância na Pesquisa
66.48%
The objective of this study was to apply factor analysis to describe lactation curves in dairy buffaloes in order to estimate the phenotypic and genetic association between common latent factors and cumulative milk yield. A total of 31 257 monthly test-day milk yield records from buffaloes belonging to herds located in the state of São Paulo were used to estimate two common latent factors, which were then analysed in a multi-trait animal model for estimating genetic parameters. Estimates of (co)variance components for the two common latent factors and cumulated 270-d milk yield were obtained by Bayesian inference using a multiple trait animal model. Contemporary group, number of milkings per day (two levels) and age of buffalo cow at calving (linear and quadratic) as covariate were included in the model as fixed effects. The additive genetic, permanent environmental and residual effects were included as random effects. The first common latent factor (F1) was associated with persistency of lactation and the second common latent factor (F2) with the level of production in early lactation. Heritability estimates for Fl and F2 were 0.12 and 0.07, respectively. Genetic correlation estimates between El and F2 with cumulative milk yield were positive and moderate (0.63 and 0.52). Multivariate statistics employing factor analysis allowed the extraction of two variables (latent factors) that described the shape of the lactation curve. It is expected that the response to selection to increase lactation persistency is higher than the response obtained from selecting animals to increase lactation peak. Selection for higher total milk yield would result in a favourable correlated response to increase the level of production in early lactation and the lactation persistency.

Milk yield persistency in Brazilian Gyr cattle based on a random regression model

Pereira, R. J.; Verneque, R. S.; Lopes, P. S.; Santana, M. L.; Lagrotta, M. R.; Torres, R. A.; Vercesi Filho, A. E.; Machado, M. A.
Fonte: Funpec-editora Publicador: Funpec-editora
Tipo: Artigo de Revista Científica Formato: 1599-1609
ENG
Relevância na Pesquisa
66.51%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); With the objective of evaluating measures of milk yield persistency, 27,000 test-day milk yield records from 3362 first lactations of Brazilian Gyr cows that calved between 1990 and 2007 were analyzed with a random regression model. Random, additive genetic and permanent environmental effects were modeled using Legendre polynomials of order 4 and 5, respectively. Residual variance was modeled using five classes. The average lactation curve was modeled using a fourth-order Legendre polynomial. Heritability estimates for measures of persistency ranged from 0.10 to 0.25. Genetic correlations between measures of persistency and 305-day milk yield (Y305) ranged from -0.52 to 0.03. At high selection intensities for persistency measures and Y305, few animals were selected in common. As the selection intensity for the two traits decreased, a higher percentage of animals were selected in common. The average predicted breeding values for Y305 according to year of birth of the cows had a substantial annual genetic gain. In contrast, no improvement in the average persistency breeding value was observed. We conclude that selection for total milk yield during lactation does not identify bulls or cows that are genetically superior in terms of milk yield persistency. A measure of persistency represented by the sum of deviations of estimated breeding value for days 31 to 280 in relation to estimated breeding value for day 30 should be preferred in genetic evaluations of this trait in the Gyr breed...

Relationship between udder measurements and milk yield in Bergamasca ewes in Brazil

Emediato, R. M. S.; Siqueira, E. R.; Stradiotto, M. M.; Maesta, S. A.; Fernandes, S.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 232-235
ENG
Relevância na Pesquisa
66.53%
The present work aimed to evaluate udders of Bergamasca ewes and their correlation with milk yield in a mix system of milk yield. Seventy-seven ewes were fed with balanced concentrate starting 20 days before lambing until the end of the experiment. The lambs stayed with their mothers in pastures during the day and were separated at night. They returned to their mothers after the morning milking and were weaned at 45 days of age. Forty-eight hours after lambing, ewes were machine milked once daily at 7 am and the milk yield was recorded for a period of 60 days. Measurements of circumference, depth and width of the udder, and width and length of teats, at 30 and 60 days, were taken. A higher average daily yield of commercial milk was observed after lambs weaning (0.509 vs. 0.435 kg/ewe/day) than before. In the same way, the correlations between udder depth, circumference and width and milk yield were positive and significant only after weaning (0.74, 0.75 and 0.62, respectively). Udder measures had positive correlations with milk yield and can be used in programs of milk yield improvement. (c) 2007 Elsevier B.V. All rights reserved.

Factors that cause genotype by environment interaction and use of a multiple-trait herd-cluster model for milk yield of Holstein cattle from Brazil and Colombia

Cerón-Muñoz, M. F.; Tonhati, Humberto; Costa, C. N.; Rojas-Sarmiento, D.; Echeverri Echeverri, D. M.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 2687-2692
ENG
Relevância na Pesquisa
66.24%
Descriptive herd variables (DVHE) were used to explain genotype by environment interactions (G x E) for milk yield (MY) in Brazilian and Colombian production environments and to develop a herd-cluster model to estimate covariance components and genetic parameters for each herd environment group. Data consisted of 180,522 lactation records of 94,558 Holstein cows from 937 Brazilian and 400 Colombian herds. Herds in both countries were jointly grouped in thirds according to 8 DVHE: production level, phenotypic variability, age at first calving, calving interval, percentage of imported semen, lactation length, and herd size. For each DVHE, REML bivariate animal model analyses were used to estimate genetic correlations for MY between upper and lower thirds of the data. Based on estimates of genetic correlations, weights were assigned to each DVHE to group herds in a cluster analysis using the FASTCLUS procedure in SAS. Three clusters were defined, and genetic and residual variance components were heterogeneous among herd clusters. Estimates of heritability in clusters 1 and 3 were 0.28 and 0.29, respectively, but the estimate was larger (0.39) in Cluster 2. The genetic correlations of MY from different clusters ranged from 0.89 to 0.97. The herd-cluster model based on DVHE properly takes into account G x E by grouping similar environments accordingly and seems to be an alternative to simply considering country borders to distinguish between environments.

Genetic parameters for test-day milk yield, 305-day milk yield, and lactation length in Guzerat cows

Santos, D. J A; Peixoto, M. G C D; Borquis, R. R A; Verneque, R. S.; Panetto, J. C C; Tonhati, Humberto
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 114-119
ENG
Relevância na Pesquisa
66.49%
Milk production in tropical environments requires the use of crossbreeding systems including breeds well adapted to harsh conditions, but with lower productivities when compared to specialized breeds. Besides the genetic improvement for milk production, lactation lengths also need to be studied for most of these breeds. Accordingly, genetic parameters were estimated for 305-day cumulative milk yield (MY305), test-day milk yield (TDMY), and lactation length (LL) using information from the first lactations of 2816 Guzerat cows selected for milk production in 28 herds in Brazil. Contemporary groups were defined as herd, year and season of the test for TDMY, and as herd, year and season of calving for MY305 and LL. Variance components were estimated with the restricted maximum likelihood method under a multi-trait animal model. Heritabilities estimated for TDMY ranged from 0.16 to 0.24, and were 0.24 and 0.12 for MY305 and LL, respectively. Genetic correlations were high and positive, ranging from 0.51 to 0.99 among TDMY records, from 0.81 to 0.98 between each TDMY and MY305, and from 0.71 to 0.94 between each TDMY and LL. Genetic parameters obtained in this study indicated the possibility of using test-day records for the prediction of breeding values for milk yield in this population of the Guzerat breed. The use of TDMY as selection criteria would result in indirect gains in MY305 and LL. However...

Genetic Parameter Estimates for Milk Yield and Lactation Length in Buffalo

Garcia, Yenny; Fraga, Luis M.; Tonhati, Humberto; Abreu, Daniel; Aspilcueta, Raul; Hernandez, Arelis; Padron, Eulogio; Guzman, Gladys; Mora, Marta; Quinonez, Dayron
Fonte: Int Buffalo Information Ctr Publicador: Int Buffalo Information Ctr
Tipo: Artigo de Revista Científica Formato: 714-716
ENG
Relevância na Pesquisa
66.4%
The objective of this study was to estimate genetic parameters for milk yield at 244 days and lactation length in graded buffalo cows at the El Cangre Cattle Genetic Enterprise. Data were gathered from 2575 lactations, 1377 buffalo cows, 37 milking units and between 2002-2009 calving years. It was employed the Restricted Maximum Likelihood method (REML) for estimating (co) variance components with multi trait model. Average of milk yield at 244 days and lactation length were 864 kg and 240 days, respectively. Heritability was 0.15 for milk yield and 0.13 for lactation length. Genetic correlation between these traits was 0.63. It was concluded that it is necessary to intensify selection and to increase control of the information of the genetic herds to obtain high precision in the estimates and therefore, obtain bigger genetic progress in of this species in our country.

Estimates of correction factors for lactation length and genetic parameters for milk yield in buffaloes

Tonhati,H.; Muñoz,M.F.C.; Duarte,J.M.C.; Reichert,R.H.; Oliveira,J.A.; Lima,A.L.F.
Fonte: Universidade Federal de Minas Gerais, Escola de Veterinária Publicador: Universidade Federal de Minas Gerais, Escola de Veterinária
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2004 EN
Relevância na Pesquisa
66.47%
Correction factors for milk yield at 90, 240, 270 and 305 days of lactation of buffaloes and genetic and environmental parameters for milk yield of these lactation periods were estimated. The data used consisted of 3888 lactation records of 1630 buffaloes from 10 herds reared in the State of São Paulo. Genetic parameters were estimated by the derivative free restricted maximum likelihood method, fitting an animal repeatability model. Heritability estimates for milk yield corrected for 90, 240, 270 and 305 days of lactation were 0.17, 0.15, 0.14 and 0.14, respectively. In this same order, repeatability estimates were 0.40, 0.44, 0.41 and 0.41. The genetic correlation estimates between these corrected milk yields ranged from 0.96 to 1.00. The multiplicative correction factors for the different classes of lactation lengths were efficient for adjustment of milk yield at 90, 240, 270 and 305 days of lactation.

Supplementation of dairy cows with propylene glycol during the periparturient period: effects on body condition score, milk yield, first estrus post-partum, beta-hydroxybutyrate, non-esterified fatty acids and glucose concentrations

Fonseca,Luís Fernando Laranja da; Rodrigues,Paulo Henrique Mazza; Santos,Marcos Veiga dos; Lima,André Pinto; Lucci,Carlos de Sousa
Fonte: Universidade Federal de Santa Maria Publicador: Universidade Federal de Santa Maria
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2004 EN
Relevância na Pesquisa
66.4%
The objective of this study was to analyse the effects of propylene glycol (PPG) supplementation to periparturient cows on: milk yield, changes in body condition score (BCS), days to first oestrus after calving, and on the beta-hydroxybutyrate (BHBA), non-esterefied fatty acids (NEFA) and glucose concentrations. Twenty-three Holstein cows were distributed into two treatments: a) 300 mL of PPG (group treatment, 11 cows), b) 300 mL of water (group control, 12 cows), administered via drench in periparturient period. BCS was evaluated on days -10, 0, 15, 30, 45 and 60 relative to calving date. There was no effect of treatment or time on milk yield, although the interaction of time*treatment was significant and during the 4th and 5th week of lactation, milk yield was significant higher in treatment group. Days to first oestrus of PPG and control group were on average 40.2 and 45.2 respectively (P>0.05). There was no effect of treatment on body condition score (BCS) from calving to sixty days post partum. There was no effect of treatment or interaction of time*treatment on plasma parameters (BHBA, NEFA and glucose) but there was an effect of time on glucose and NEFA. However, based on an analysis of covariance, using BCS as the covariate...

Estimation of genetic parameters for test-day milk yield in Holstein cows using a random regression model

Cobuci,Jaime Araujo; Euclydes,Ricardo Frederico; Lopes,Paulo Sávio; Costa,Claudio Napolis; Torres,Robledo de Almeida; Pereira,Carmen Silva
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2005 EN
Relevância na Pesquisa
66.45%
Test-day milk yield records of 11,023 first-parity Holstein cows were used to estimate genetic parameters for milk yield during different lactation periods. (Co)variance components were estimated using two random regression models, RRM1 and RRM2, and the restricted maximum likelihood method, compared by the likelihood ratio test. Additive genetic variances determined by RRM1 and additive genetic and permanent environmental variances estimated by RRM2 were described, using the Wilmink function. Residual variance was constant throughout lactation for the two models. The heritability estimates obtained by RRM1 (0.34 to 0.56) were higher than those obtained by RRM2 (0.15 to 0.31). Due to the high heritability estimates for milk yield throughout lactation and the negative genetic correlation between test-day yields during different lactation periods, the RRM1 model did not fit the data. Overall, genetic correlations between individual test days tended to decrease at the extremes of the lactation trajectory, showing values close to unity for adjacent test days. The inclusion of random regression coefficients to describe permanent environmental effects led to a more precise estimation of genetic and non-genetic effects that influence milk yield.

Effects of genetic polymorphisms at the growth hormone gene on milk yield in “Serra da Estrela” sheep

Marques, M. Rosário; Santos, Ingrid; Carolino, N.; Belo, Carmona; Renaville, Robert; Cravador, A.
Fonte: Universidade do Algarve Publicador: Universidade do Algarve
Tipo: Artigo de Revista Científica
Publicado em //2006 ENG
Relevância na Pesquisa
66.5%
The five exons and the 5' and 3'-untranslated regions (5'-UTR and 3'-UTR) of the oGH gene were screened for mutations using PCR-single strand conformation polymorphism (PCR-SSCP) procedures in 523 Serra da Estrela ewes and were found to be highly polymorphic. The region extending across and between the GH2-N and GH2-Z copies was sequenced allowing the design of primers for the specific PCR amplification of each copy. These were cloned and sequenced in 20 animals representative of all SSCP patterns. The corresponding genotypes were established for each copy following nucleotide sequencing of SSCP alleles. Twenty-four polymorphic sites were found at the GH2-N (or GH1) and fourteen at the GH2-Z copies. Eight amino acid substitutions were predicted at the GH2-N and six at the GH2-Z copies. Milk yield adjusted to 150 lactation days was analysed for the genotype of each oGH gene copy taken separately or together (associated genotypes) by restricted maximum likelihood (REML) through a univariate best linear unbiased prediction (BLUP) animal model with repeated measures. Significant associations between genotypes and milk yield were observed. Within GH2-N genotypes there was a milk yield differential of 21.4+/-0.2 l/150 d between the most (N7) and the least (N5) productive ones. Within GH2-Z genotypes there was a differential of 21.6+/-0.2 l/150 d between the most (Z8) and the least (Z1) productive ones. The effect of associated GH2-N and GH2-Z genotypes revealed a differential of 39.6+/-0.3 l/150 d between the most (N1+Z7) and the least (N3+Z2) productive associated genotypes. The results show that GH2-N and GH2-Z genotypes significantly affect milk yield in Serra da Estrela ewes. Moreover...

Association of IGF-I gene polymorphisms with milk yield and body size in Chinese dairy goats

Deng,Chanjuan; Ma,Rongnuan; Yue,Xiangpeng; Lan,Xianyong; Chen,Hong; Lei,Chuzhao
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
Relevância na Pesquisa
66.29%
The association of IGF-I gene polymorphisms with certain traits in 708 individuals of two Chinese dairy-goat breeds (Guanzhong and Xinong Saanen) was investigated. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing methods were employed in screening for genetic variation. Two novel mutations were detected in the 5'-flanking region and in intron 4 of IGF-I gene, viz., g.1617 G > A and g.5752 G > C (accession D26119.2), respectively. The associations of the g.1617 G > A mutation with milk yield and the body size were not significant (p > 0.05). However, in the case of g.5752 G > C, Xinong Saanen dairy goats with the CG genotype presented longer bodies (p < 0.05). Chest circumference (p < 0.05) was larger in Guanzhong goats with the GG genotype. In Xinong Saanen dairy goats with the CC genotype, milk yields were significantly higher during the first and second lactations (p < 0.05). Hence, the g.5752 G > C mutation could facilitate association analysis and serve as a genetic marker for Chinese dairy-goat breeding and genetics.

Cubic-spline interpolation to estimate effects of inbreeding on milk yield in first lactation Holstein cows

Geha,Makram J.; Keown,Jeffrey F.; Van Vleck,L. Dale
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
66.45%
Milk yield records (305d, 2X, actual milk yield) of 123,639 registered first lactation Holstein cows were used to compare linear regression (y = β0 + β1X + e) ,quadratic regression, (y = β0 + β1X + β2X2 + e) cubic regression (y = β0 + β1X + β2X2 + β3X3 + e) and fixed factor models, with cubic-spline interpolation models, for estimating the effects of inbreeding on milk yield. Ten animal models, all with herd-year-season of calving as fixed effect, were compared using the Akaike corrected-Information Criterion (AICc). The cubic-spline interpolation model with seven knots had the lowest AICc, whereas for all those labeled as "traditional", AICc was higher than the best model. Results from fitting inbreeding using a cubic-spline with seven knots were compared to results from fitting inbreeding as a linear covariate or as a fixed factor with seven levels. Estimates of inbreeding effects were not significantly different between the cubic-spline model and the fixed factor model, but were significantly different from the linear regression model. Milk yield decreased significantly at inbreeding levels greater than 9%. Variance component estimates were similar for the three models. Ranking of the top 100 sires with daughter records remained unaffected by the model used.

Variação genética das características do pelame e da produção de leite em vacas Holandesas manejadas à sombra em ambiente tropical; Genetic variation of the hair coat properties and the milk yield of Holstein cows managed under shade in a tropical environment

Maia, Alex Sandro Campos; Silva, Roberto Gomes da; Bertipaglia, Elaine Cristina Abaker; Muñoz, Mario Cerón
Fonte: Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia Publicador: Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; ; Formato: application/pdf
Publicado em 01/01/2005 ENG
Relevância na Pesquisa
66.46%
O presente estudo realizou uma avaliação genética e ambiental dos efeitos da cor e das características físicas do pelame sobre a produção de leite na primeira lactação de vacas Holandesas manejadas sobre sombra. Os dados são pertencentes a 449 vacas Holandesas e foram analisados pelo método de quadrados mínimos. O método da Máxima Verossimilhança Restrita (REML) foi utilizada para estimar os componentes de variância e covariância sob o modelo Animal. Os resultados mostraram que vacas Holandesas predominantemente brancas tendem a apresentar maior produção de leite do que aquelas predominantemente negras em um ambiente tropical, quando manejadas em free-stall providos de ventilação e aspersão. As características físicas do pelame apresentaram uma associação negativa com a produção de leite, exceto o diâmetro dos pêlos. Essa associação favorece a transferencia de calor através do pelame e, é amplamente favorável em ambientes quentes. As altas estimativas de herdabilidade juntamente com as altas correlações genéticas da produção de leite com aquelas propriedades físicas do pelame é uma evidencia da possibilidade de realizar uma seleção genética para aumento da produção de leite juntamente com uma seleção na direção de um pelame menos denso com pêlos grossos...

Prediction of 305-day milk yield in Brown Swiss cattle using artificial neural networks

Gorgulu,O.
Fonte: South African Journal of Animal Science Publicador: South African Journal of Animal Science
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
Relevância na Pesquisa
66.33%
Artificial neural networks (ANNs) have been shown to be a powerful tool for system modelling in a wide range of applications. In this paper, we focus on the capability of ANNs to predict 305-d milk yield in early lactation of Brown Swiss cattle, based on a few test-day records, and some environmental factors such as age, number of lactation and season of calving. The ANNs that were developed were compared with multiple linear regressions (MLR). The various ANNs were modelled and the best performing number of hidden layers, neurons and training algorithms retained. The best ANN model had input, hidden and output layers of tansig transfer function. The layers had 4, 8, and 1 neurons, respectively. It was determined that the mean predicted values calculated by the ANNs were closer to the real mean values without showing any statistical difference. On the other hand, the predicted mean values calculated by MLR and the real mean values were significantly different from each other. The best prediction in ANN method was seen in 1st, 2nd, 3rd, and 4th test-day records when these were recorded to the system as X1-X8 in the ANN system. In this study, the prediction of 305-d milk yield by ANN gave better results that those of MLR, suggesting that ANN can be used as an alternative prediction tool.