Navegando por Autor "Silva, Marcos Vinícius Gualberto Barbosa da"
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Item Análise de diversidade genética do gene da osteopontina em bovinos da raça girolando(2011) Mello, Fernanda de; Guimarães, Marta Fonseca Martins; Cobuci, Jaime Araújo; Silva, Marcos Vinícius Gualberto Barbosa da; Braccini Neto, José; Paiva, Daisyléa de SouzaThe objective was to obtain the indices of genetic diversity for the SNP (single nucleotide polymorphism) of the 4 intron osteopontin gene (OPN) for 434 animals (87 bulls and 347 cows) participants in the Teste de Progênie da raça girolando (Girolando Progeny Test) in Brazil. For amplification, primers used were described for the Holstein breed, and differentiation of alleles C/T SNP that was obtained by PCR-RFLP. Genotype frequencies of TT (52.53%), CT (38.71%) and CC (8.76%) and allele frequencies of T (71.9%) and C (28.1%) indicate that the population is in Hardy-Weinberg principle (HWP). Although the OPN gene locus is in HWP, the higher frequency of allele T of SNP in these animals may suggest a setting-trend of allele T in the race. No difference was observed between the group of bulls and cows (F ST = -0.018), supporting the estimate of population balance. Considering the values estimated by the F IS (0.043), it is likely that high numbers of individuals homozygous for the T allele observed in the population occur because of possible inheritance of this allele coming from the zebu breed, rather than inbreeding. Thus, to better characterize the OPN gene polymorphism, assessments in a larger number of animals must be performed, since only animals that participated in the Progeny Test were assessed. Objetivou-se obter os índices de diversidade genética para o SNP (single nucleotide polymorphism) do íntron 4 do gene da osteopontina (OPN) para 434 animais (87 touros e 347 vacas) participantes do Teste de Progênie da raça girolando no Brasil. Para a amplificação, foram utilizados primers descritos para a raça holandesa, e a diferenciação dos alelos C/T desse SNP foi obtida por meio da técnica de PCR-RFLP. As frequências genotípicas TT (52,53%), CT (38,71%) e CC (8,76%) e as frequências alélicas de T (71,9%) e C (28,1%) indicam que a população encontra-se em Equilíbrio de Hardy-Weinberg (EHW). Apesar de o loco do gene OPN estar em EHW, a frequência superior do alelo T do SNP nesses animais pode sugerir uma tendência de fixação do alelo T na raça. Não foi observada diferenciação entre o grupo de touros e vacas (F ST = -0,018), corroborando a estimativa de equilíbrio da população. Considerando os valores estimados pelo F IS (0,043), é possível que ocorram altos números de indivíduos homozigotos para o alelo T observados na população, em virtude da provável herança desse alelo vindo da raça zebuína, e não a endogamia. Assim, para melhor caracterização do polimorfismo do gene OPN, devem ser realizadas avaliações em maior número de animais, uma vez que só foram avaliados animais participantes do teste de progênie.Item Breed, heterosis, and recombination effects for lactation curves in Brazilian cattle(2021) Daltro, Darlene dos Santos; Padilha, Alessandro Haiduck; Gama, Luís Telo da; Silva, Marcos Vinícius Gualberto Barbosa da; Cobuci, Jaime AraujoABSTRACT The objective of this study was to estimate the breed, heterosis, and recombination effects on different components of the lactation curve of Girolando cattle. The dataset used consisted of 12,121 purebred cows of Holstein (H) and Gyr (G) breeds, and six H×G crossbred cows (Girolando). The model used presents random effects of herd and cow, regression coefficient associated with linear effect of proportion of H breed, regression coefficient associated with the linear effect of heterosis between H and G breeds, regression coefficient associated with the linear effect of recombination between H and G breeds, and random effect of residual. Dijkstra's (DJ), Nelder's (ND), Wilmink's (WL), and Wood's (WD) models were tested to fit production records of these different genetic groups. These models were then tested according to evaluation criteria of quality of fit (AIC, BIC, and RMSE), and the two best models (WD and WL) were chosen for estimation of 305-day milk yield (MY305), peak yield, time to peak, and persistency of milk yield. The breed effect was significant for all traits and components of the lactation curve. The heterosis effect was significant for all traits, and was more significant for MY305 (945.62±79.17 kg). Peak yield was the component of lactation curve that presented the most significant heterosis effect, partially explaining the heterosis effect (12 to 21%) found for MY305. The recombination effect was positive only for lactation period and time to peak of lactation in Girolando cows.Item Estimativas de tendência genética para características produtivas em um rebanho do ecótipo Mantiqueira(2001) Silva, Marcos Vinícius Gualberto Barbosa da; Ferreira, William José; Cobuci, Jaime Araujo; Guaragna, Guilherme Paes; Oliveira, Paulo Rogério Palma deThe data used in this study are from the first five lactations of 1,406 cows of the Mantiqueira Ecotype, daughters of 113 sires, with calving from 1952 to 1997. The total milk yield (PL), fat production (PG), lactation period (DL), and days dry (PS) were obtained from NPZGJRA/IZ/APTA/SAA. Based on the genetic values predictions, for each studied feature selection differentials and genetic trends were estimated though four selection paths of selection: bulls to breed bulls (SB), cows to breed bulls (DB), bulls to breed cows (SC) and cows to breed cows (DC). Two periods were involved: the first, from 1952 to 1976, representing the formation period and herd increase, the second, from 1977 to 1997, when the breeding program was implemented. The whole period from 1952 to 1997 was also considered. MTDFREML was used in the analysis with an animal model containing the year-season effects of calving, lactation period, the linear and quadratic effects of age of calving as fixed effects. Animal and permanent environment and error were included as random effects. The selection differentials for the SB and SC paths were larger in the first period. DB and DC paths were larger in the second period due to changes in the selection criterion. Selected gains for PG, DL, and PS paths were very small suggesting that the selection was only for PL. Rates of gains could be increased with changes in the breeding program. Os registros utilizados neste estudo foram provenientes das cinco primeiras lactações de 1406 vacas do ecótipo Mantiqueira, filhas de 113 reprodutores, com partos entre os anos de 1952 e 1997. As informações sobre as características produção total de leite (PL), produção de gordura (PG), duração da lactação (DL) e período seco (PS) foram obtidas do NPZGJRA/IZ/APTA/SAA. Com base nas predições dos valores genéticos, para cada característica estudada, estimaram-se os diferenciais de seleção e as tendências genéticas, por meio de quatro trajetórias de seleção: touros pais de touros (SB), vacas mães de touros (DB), touros pais de vacas (SC) e vacas mães de vacas (DC). Os períodos estudados compreenderam os anos de 1952 a 1976, primeiro período, que representou a formação e a ampliação do rebanho; de 1977 a 1997, segundo período, caracterizado pela implementação de um programa de melhoramento genético do ecótipo; e de 1952 a 1997, período total. As análises foram feitas por meio do sistema MTDFREML, com um modelo animal que incluiu os efeitos fixos de ano-estação de parto e duração da lactação e, como covariável, a idade da vaca no parto, em meses, com termos linear e quadrático. Como efeitos aleatórios foram incluídos animal, efeito permanente de meio e erro. Verificou-se que os diferenciais de seleção das trajetórias SB e SC foram superiores aos das demais trajetórias, no primeiro período, enquanto no segundo período, no entanto, em razão da mudança de critério de seleção, os diferenciais de seleção das trajetórias DB e DC foram maiores. As tendências genéticas obtidas para PG, DL e PS foram inexpressivas, o que sugere que a seleção tenha sido direcionada somente para PL. As taxas de ganho genético podem ser aumentadas, razão pela qual o programa de melhoramento deve ser reestruturado.Item Genetic analysis of productive and reproductive traits in multiple-breed dairy cattle populations(2017) Ribeiro, Virgínia Mara Pereira; Merlo, Fernanda Albuquerque; Gouveia, Gabriela Canabrava; Winkelstroter, Larissa Kretli; Abreu, Luíza Rodrigues Alves; Silva, Marcos Vinícius Gualberto Barbosa da; Panetto, João Cláudio do Carmo; Paiva, Leandro de Carvalho; Cembranelli, Marcello de Aguiar Rodrigues; Toral, Fabio Luiz BuraneloAbstract: The objective of this work was to determine whether the random regression model using linear splines (RRMLS) is suitable to estimate the genetic parameters for productive and reproductive traits of a multiple-breed dairy cattle population, as well as to investigate the effect of the genetic group of the progeny on the genetic merit of the sire. The multiple-trait model (MTM) and the RRMLS with one knot fitted for every genetic group were used to obtain the genetic parameters. Records of 1/2 Holstein + 1/2 Gyr (1/2HG), 5/8 Holstein + 3/8 Gyr (5/8HG), and 3/4 Holstein + 1/4 Gyr (3/4HG) crossbreed dams were considered. The RRMLS showed better fitting. The additive and residual variances estimated by the MTM and the RRMLS were similar. Heritability varied from 0.20 to 0.33 for age at first calving, from 0.09 to 0.22 for first lactation length, and from 0.15 to 0.35 for first lactation 305-day milk yield, according to the genetic composition of the dams. The RRMLS is suitable to estimate the genetic parameters for productive and reproductive traits of multiple-breed dairy cattle populations. The genetic merit of the sires is affected by the genetic group of the progeny by which they are evaluated. Resumo: O objetivo deste trabalho foi verificar se o modelo de regressão aleatória com polinômios lineares do tipo spline (MRAPLS) é adequado para estimar os parâmetros genéticos de características produtivas e reprodutivas em uma população multirracial de bovinos leiteiros, bem como investigar o efeito do grupo genético da progênie sobre o mérito genético do touro. Foram utilizados o modelo multicaracterístico (Mult) e o MRAPLS com nós ajustados aos grupos genéticos, para obtenção dos parâmetros genéticos. Foram considerados os registros de vacas 1/2 Holandesa + 1/2 Gir (1/2HG), 5/8 Holandesa + 3/8 Gir (5/8HG) e 3/4 Holandesa + 1/4 Gir (3/4HG). O MRAPLS apresentou os melhores ajustes. As variâncias aditivas e residuais estimadas por Mult e MRAPLS foram semelhantes. As herdabilidades variaram de 0,20 a 0,33 para idade ao primeiro parto, de 0,09 a 0,22 para duração da primeira lactação e de 0,15 a 0,35 para produção de leite em até 305 dias na primeira lactação, de acordo com a composição genética das vacas. O MRAPLS é adequado para estimar parâmetros genéticos de características produtivas e reprodutivas em populações multirraciais de bovinos leiteiros. O mérito genético do touro é influenciado pelo grupo genético da progênie por meio do qual ele é avaliado.Item Infrared thermography as a method for evaluating the heat tolerance in dairy cows(2017) Daltro, Darlene dos Santos; Fischer, Vivian; Alfonzo, Evelyn Priscila München; Dalcin, Vanessa Calderaro; Stumpf, Marcelo Tempel; Kolling, Giovani Jacob; Silva, Marcos Vinícius Gualberto Barbosa da; McManus, ConceptaABSTRACT The objective of this study was to determine whether infrared thermography is a useful tool for the recognition of dairy cows in a state of thermal heat stress, as well as to identify the best region of the animal to be evaluated for this recognition. Physiological variables, including rectal temperature, respiratory frequency, cardiac frequency, and panting score were recorded in 38 lactating cows. For the assessment of environmental parameters, a digital black globe thermometer (TGD-200 model) was used. Thermographic photographs of different regions of the body of cows were taken using an infrared camera (FLIR® System T300) and indicated respective superficial temperature. Physiological variables and superficial body temperature in different regions varied between genetic groups (Girolando: ½ Holstein × ½ Gir and ¾ Holstein × ¼ Gir; purebred Holstein). The environmental temperature ranged from 20.7 to 37.9 °C with a relative humidity reaching 95%. The mean rectal temperature (40.84 °C), respiratory frequency (111.36 breaths/min), and cardiac frequency (99.22 beats/min) were higher for pure Holstein than for Girolando cows. Positive correlations were found between the physiological parameters and thermographic measures. The highest positive correlation (0.74) was found between the temperature in the lateral region of the udder and rectal temperature. Thermography is a good indicator of thermal comfort. The best region to identify heat stress in cows using thermography is the lateral region of the udder.Item Physiological parameters for thermal stress in dairy cattle(2016) Dalcin, Vanessa Calderaro; Fischer, Vivian; Daltro, Darlene dos Santos; Alfonzo, Evelyn Priscila München; Stumpf, Marcelo Tempel; Kolling, Giovani Jacob; Silva, Marcos Vinícius Gualberto Barbosa da; McManus, ConceptaABSTRACT The objective of this study was to investigate changes in physiological parameters of dairy cows and understand which physiological parameters show greater reliability for verification of heat stress. Blood samples were collected for analysis and included hematocrit (Ht), erythrocyte count (ERY), and hemoglobin count (HEMO). In addition, physiological variables, including rectal temperature (RT), heart rate (HR), respiratory rate (RR), and panting score (PS) were recorded in 38 lactating cows. These varied according to genetic group (1/2, 3/4, and pure bred Holstein (HO)). Analysis of variance considering the effects of genetic group, days, and their interaction as well as linear and quadratic effect of the black globe humidity index (BGHI) was performed, as well as broken-line regression. These values were higher in pure HO than in 3/4 and 1/2 groups. The average BGHI during the morning was 74, when 70, 43, and 13% of pure HO, 3/4, and 1/2, respectively, presented RR above reference value. The RR was the best indicator of heat stress and its critical value was 116 breaths/min for 1/2, 140 for 3/4, and 168 breaths/min for pure HO cows. In the HO group, physiological variables increased linearly with BGHI, without presenting inflection in the regression. The inflection point occurred at a higher BGHI for the 1/2 group compared with the other groups. Hematocrit and HEMO were different among genetic groups and did not vary with BGHI, showing that stress was not sufficient to alter these hematological parameters. The 1/2 HO group was capable of maintaining normal physiological parameters for at least 3 BGHI units above that of HO and 1 to 3 units higher than 3/4 HO for RR and RT, respectively. Respiratory rate is the physiological parameter that best predicts heat stress in dairy cattle, and the 1/2 Holstein group is the best adapted to heat stress.Item Physiological parameters for thermal stress in dairy cattle(2016) Dalcin, Vanessa Calderaro; Fischer, Vivian; Daltro, Darlene dos Santos; Alfonzo, Evelyn Priscila München; Stumpf, Marcelo Tempel; Kolling, Giovani Jacob; Silva, Marcos Vinícius Gualberto Barbosa da; McManus, ConceptaABSTRACT The objective of this study was to investigate changes in physiological parameters of dairy cows and understand which physiological parameters show greater reliability for verification of heat stress. Blood samples were collected for analysis and included hematocrit (Ht), erythrocyte count (ERY), and hemoglobin count (HEMO). In addition, physiological variables, including rectal temperature (RT), heart rate (HR), respiratory rate (RR), and panting score (PS) were recorded in 38 lactating cows. These varied according to genetic group (1/2, 3/4, and pure bred Holstein (HO)). Analysis of variance considering the effects of genetic group, days, and their interaction as well as linear and quadratic effect of the black globe humidity index (BGHI) was performed, as well as broken-line regression. These values were higher in pure HO than in 3/4 and 1/2 groups. The average BGHI during the morning was 74, when 70, 43, and 13% of pure HO, 3/4, and 1/2, respectively, presented RR above reference value. The RR was the best indicator of heat stress and its critical value was 116 breaths/min for 1/2, 140 for 3/4, and 168 breaths/min for pure HO cows. In the HO group, physiological variables increased linearly with BGHI, without presenting inflection in the regression. The inflection point occurred at a higher BGHI for the 1/2 group compared with the other groups. Hematocrit and HEMO were different among genetic groups and did not vary with BGHI, showing that stress was not sufficient to alter these hematological parameters. The 1/2 HO group was capable of maintaining normal physiological parameters for at least 3 BGHI units above that of HO and 1 to 3 units higher than 3/4 HO for RR and RT, respectively. Respiratory rate is the physiological parameter that best predicts heat stress in dairy cattle, and the 1/2 Holstein group is the best adapted to heat stress.