Tarcisio de Moraes Gonçalves

Parâmetros genéticos de longevidade e produtividade de fêmeas da raça Nelore

In order to estimate the (co)variance components, heritabilities and genetic correlations of longevity and herd life in females, informations of 56,413 births of females from a Nellore cattle herd, from 1950 to 2000, under different rearing and management conditions, were used. It was studied from calf: weaning weight (W205C), yearling weight (W365C), weight in 550 days (W550C), from cows: weaning weight (W205), yearling weight (W365) and weight in 550 days (W550), age at first calving (AFC), calving interval (CI), herd life (RL), longevity (LONG), reproductive efficiency (RE), index production (IP), index of metabolic production (IMP), sum of index production (SIP), sum of index metabolic production (SIMP). The analysis were performed using the MTDFREML software, estimating (co)variance components, assuming animal model. Direct genetic, maternal and permanent environmental effects were analyzed. Fixed effects of farm, feeding program, rearing condition, birth calf year, birth calf season and calf sex, were also analyzed. Heritability estimates showed similar results among the different analyses, higher (0.24 to 0.75) for W205, W365, W550, W205C, W365C, W550C, IP, IMP, AFC, RL, LONG and lower (0 to 0.10) for RE, CI, SIP and SIMP. Some correlations between maternal genetic effect and the growth traits were negative. In general, estimates of genetic and phenotypic correlations among LONG and growth traits were negative, suggesting genetic antagonism between LONG and early maturity, between the LONG and reproductive and productive traits were positive, suggesting the significant effect of reproductive and productive traits on LONG.

Fatty acid profile and qualitative characteristics of meat from zebu steers fed with different oilseeds

The objective of this study was to evaluate the effects of dietary addition of ground oilseed sources on the quality, fatty acid profile, and CLA content of meat from zebu steers. Thirty-one zebu steers with an initial average age of 23 mo and an initial BW of 365 kg were used in this study. The experimental period was 84 d, which was preceded by an adaption period of 28 d. The diet was provided ad libitum with a forage:concentrate ratio of 40:60. Corn silage was used as the forage source. Four different concentrates were formulated for each treatment: without additional lipids (control) or with ground soybeans (SB), ground cottonseed (CS), or ground linseed (LS). The SB, CS, and LS diets were formulated to have 6.5% ether extract on a total dietary DM basis. The experiment was set up as a completely randomized design. After slaughter, samples were taken from the longissimus thoracis muscle for the measurement of fatty acid concentration and the evaluation of meat quality. The luminosity index was greater in the control and LS diets (P < 0.01). The greatest percentages of myristic acid (C14:0), palmitic acid (C16:0), trans octadecenoic acid (C18:1 trans-10, trans-11, or trans-12), and SFA in the subcutaneous fat were observed in the CS treatment (P < 0.01). Moreover, the least percentages of oleic acid (C18:1 cis-9) and total unsaturated fatty acids in the subcutaneous fat were observed in the CS diet (P < 0.01). The meat linoleic acid and α-linolenic acid percentages were greatest in the SB and LS treatments, respectively (P < 0.001). The unsaturated fatty acid:SFA ratio was smallest for the CS diet (P < 0.01). A gradual increase in oxidation was observed as a function of storage time; however, the diets did not affect the rancidity of the meat (P > 0.05). The fatty acid profile of subcutaneous fat was impaired by the addition of CS. Supplying ground oilseeds did not increase the content of CLA in the meat.

Qualidade da carne maturada de bovinos Red Norte e Nelore

The objective in this study was to evaluate meat quality of longissimus thoracisi muscle during ageing. Samples from 22 Nelore bovines and 22 Red Norte males at 24 months of age were collected at 24 hours post mortem, kept at 2oC and analyzed on days 1, 7, 14 and 21. The animals were finished in confinement (112 days) with corn silage (50%) and concentrate (50%) ad libitum. Values of final pH, cooking loss, moisture, protein, fat and ash were similar among samples of Nelore and Red Norte animals. The red level (a*) and the yellow intensity (b*) were similar among meats of the two genetic groups, however, luminosity (L*) was higher in samples of Red Norte animals. Ageing significantly affected luminosity, level of red and yellow, chroma, tone angle (H*) and subjective perception of the color (ΔE), thus, the most important changes in color occurred from 7 to 14 days. Shear force in the meat of Red Norte animals was approximately 0.9 kg lower than in Nelore animals. Ageing influenced shear force during maturation with a reduction of 1.09 kg, 0.21 kg and 0.56 kg in the periods from 1 to 7, from 7 to 14 and from 14 to 21 days, respectively. The myofibrillar fragmentation index was higher in the meat of Red Norte animals and in samples aged for 21 days. The meat of Red Norte animals showed more tenderness and luminosity. Ageing improves the tenderness of meat because it reduces shear force, however, it changes the color, whose most important changes take place from 7 to 14 days. The choice of the most appropriate ageing time for beef depends on which attribute will be considered.

Source of variation and genetic parameters of days open and days dry in Holstein dairy cattle in Minas Gerais State

The objective of this work was to evaluate the effect of some environmental factors on days open (DO) and days dry (DD), as well as to estimate genetic parameters for these traits in Holstein breed cows. A total of 6,485 records of DO and DD were used. The database were analyzed using a model that included the fixed effects of dairy group farmers, calving year, calving season, production level (PL), genetic group (GG), calving age class (CA) and the first order interactions between PL, GG and CA, and the random effect of bulls. The means, standard error and coefficients of variation for DO and DD were 121.21 (0.69) days, 46.10% and 92.27(0.59) days, 51.71%, respectively. For DO, effects of bull, dairy group farmers, calving year, calving season , PL were significant and was observed interaction between PL and GG. For DD, the effects of dairy group farmers, calving year, calving season, PL, CA and the interaction between PL and GG and for bull were significant. Genetic group did not affected the studied variables and a reduction in DO and DD with year was observed. The heritability estimate in univariate and bivariate analyses were 0.052 and 0.027 for DO, and 0.004 and 0.0001 for DD, respectively. The repeatabilities for DO and DD were 0.06 and 0.03, respectively. It was observed that the environmental effects are the most important on these traits. The genetic, phenotypic and environmental correlations between DO and DD (0.55, 0.72 and 0.73, respectively) show that cows with higher DO had greater days dry.

Reactivity, performance, color and tenderness of meat from Zebu cattle finished in feedlot

The objective of this study was to study the animal reactivity and correlate it with performance and meat quality of cattle finished in feedlots. A total of 20 animals of the Tabapua breed and 20 animals of the Nellore breed were confined for 112 days: 28 days of adaptation and 84 days of data collection. Performance was determined by the average daily weight gain (ADG) and average dry matter intake (DMI) estimated through the use of indicators. On the 1st, 42nd and 84th days of the experiment, two methods were used to measure the animal reactivity: animal reactivity in mobile cage and visual reactivity during handling. The characteristics of meat quality were evaluated by the color, shear force and pH24 after slaughter (pH24). Through the study of correlation, the degree and direction of linear association on animal reactivity, performance and meat quality were established. Regression equations were generated for the parameters evaluated according to the values of animal reactivity. Correlations between mobile cage and visual reactivity were 0.77, 0.56 and 0.45 in the 1st, 2nd and 3rd evaluations, respectively. There was no correlation between animal reactivity and DMI. The correlations between ADG, pH24, and color with animal reactivity were -0.31, 0.40, 0.47 and -0.34, and -0.33 for mobile cage, 0.74, 0.71 and -0.51, for visual reactivity, respectively. The parameters of meat quality varied according to the reactivity. Undesirable values of pH24, animal reactivity and color were found when mobile cage reactivity was higher than 780, 590 and 540, respectively. In general, animals that show greater reactivity tend to have lower daily weight gain and lower meat quality. The reactivity can be used in animal breeding programs, in order to improve performance and meat quality of Zebu cattle finished in feedlot.

Feed intake and prediction assessments using the NRC, CNCPS and BR-CORTE systems in Nellore and Red Norte steers finished in feedlot.

Este trabalho foi realizado com os objetivos de avaliar o consumo de materia seca (CMS) e dos nutrientes da dieta em novilhos Nelore e Red Norte terminados em confinamento e comparar os valores observados aos preditos por meio dos sistemas NRC (2000), CNCPS 5.0 e BR-CORTE. Utilizaram-se 41 novilhos, nao-castrados, de dois grupos geneticos, sendo 19 Nelore com peso vivo inicial medio de 361 ± 31 kg e 22 Red Norte com peso vivo inicial de 367 ± 30 kg. No inicio do periodo de adaptacao, com duracao de 28 dias, os animais foram pesados apos jejum alimentar de 16 horas e tratados contra endo e ecto parasitas. O periodo experimental teve duracao de 56 dias e, alem das pesagens nestes periodos, foram realizadas mensuracoes do consumo individual, utilizando-se os indicadores LIPE, oxido cromico e materia seca indigestivel (MSi). A comparacao entre os dados de consumo observados com aqueles preditos pelos sistemas NRC (2000), CNCPS 5.0 e BR-CORTE foi feita por meio do procedimento PROC REG do software SAS. O consumo de materia seca expresso em kg/dia nao apresentou diferencas entre os grupos geneticos (10,66 vs 10,44). Quando expresso em porcentagem do peso vivo (%PV), o consumo foi maior para os animais da raca Nelore (2,55 vs 2,39%, respectivamente) e, quando expresso em g/kg PV0,75, tendeu a ser maior para a raca Nelore (115 vs 109 g/kg PV0,75). Todos os sistemas avaliados subestimam o consumo de materia seca, entretanto ha menores diferencas entre o consumo observado e o predito para animais mesticos.

Curvas de Lactação em Rebanhos da Raça Holandesa no Estado de Minas Gerais: Escolha do Modelo de Melhor Ajuste

Para selecionar o modelo de curva de lactacao de melhor ajuste aos dados de producao de leite no dia de controle de animais da raca Holandesa no Estado de Minas Gerais, utilizaram-se 157.932 controles de 17.150 lactacoes, de 1990 a 1996, do arquivo inicial com 305.506 controles de 56.422 lactacoes, do Servico de Controle Leiteiro da ACGHMG. Ajustaram-se os dados para os fatores: regiao, nivel de producao, ano-estacao de parto, classes de ordem e idade ao parto (COPI), grupo genetico, numero de controles e interacoes, alem dos efeitos linear e quadratico da duracao da lactacao. Para verificar o melhor ajuste aos modelos Quadratico logaritmico, Gamma Incompleta, Regressao Multipla e Multifasico (Monofasico e difasico), foram usados menor desvio padrao residual, R2 ajustado ao numero de parâmetros das equacoes, autocorrelacao de primeira ordem e teste de Durbin-Watson. O uso de uma funcao difasica para predizer a producao de leite em programas de selecao e recomendado, sendo tambem possivel estimar, com base nessa funcao, a producao de leite em 305 dias.

Modelos alternativos para detecção de locos de características quantitativas (QTL) de carcaça e crescimento nos cromossomos 4, 5 e 7 de suínos

Genome scans can be used to identify chromosomal regions and eventually genes that control quantitative traits (QTL) of economic importance. In an experimental cross between Meishan (male) and Dutch Large White and Landrace lines (female), 298 F1 and 831 F2 animals were evaluated for intramuscular fat (GIM), % and growth trait: body weight gain (GP) from approximately 25 to 90 kg, g/day and 324 F1 and 805 F2 for backfat thickness, mm (ET). The animals of generations F1 and F2 were typed for 29 microsatellite markers. Linkage was studied among chromosomes 4, 6, 7 and GIM, ETand GP. QTL analyses using Bayesian methodology was applied under three genetic models: infinitesimal polygenic model (MPI); finite polygenic model (MPF) with three loci and MPF combined with MPI. The number of QTL, their map positions in the three chromosomes, and phenotypic effects were all estimated simultaneously within the same framework. The summaries of the estimated parameters were based on the marginal posterior distributions, that were obtained through Markov chain Monte Carlo (MCMC) methods. The results showed two QTLs for GIM on chromosomes 4 and 6 and two for ET on chromosomes 4 and 7. QTLs on chromosome 4 for ET and GIM were detected only under the PMI. Failure of theses approaches to detect weight gain QTL was possibly due to insufficient power from marker data or due to absence of segregating QTL on the chromosomes 4, 6 and 7 for this population. This study shows the benefit of analyzing experimental data under different genetic models and these analyses clearly illustrate the utility and wide applicability of Bayesian methodology.

Comparação de diferentes estratégias para a análise de características de crescimento e de carcaça de suínos cruzados: modelos finito e infinitesimal poligênico

A Bayesian marker-free segregation analysis was applied for the estimation of variance components and to search for evidence of segregation genes affecting two carcass traits: intramuscular fat (IMF), %, and backfat thickness (BF), mm ; and one growth trait: body weight gain (LG) from 25 to 90 kg, approximately, g/day. In this study, 1,257 animals from the F2 design produced by breeding among pigs Meishan (male) and Dutch Large White and Landrace lines (female) were used. In animal breeding, finite polygenic models (FPM) may be an alternative to the infinitesimal polygenic model (IPM) for genetic evaluation of populations with multiple-generations pedigree for quantitative traits. FPM, IPM and FPM combined with IPM were empirically tested for estimation of variance components and number of genes in FPM. Estimation of marginal posteriori means of variance components and parameters were performed by using Markov Chain Monte Carlo techniques with the Gibbs sampler and the reversible Jump sampler (Metropolis-Hastings). The results showed evidence for four Major Genes (MG), i.e., two for IMF and two BF. For BF, the MG explained almost all of genetic variance, while for IMF, MG reduced the polygenic variance significantly. The LG was not likely influenced by MG. The polygenic heritability estimates for IMF, BF and LG were 0.37, 0.24 and 0.37, respectively. Further molecular genetic research, based on the same experimental data, aiming to map the major genes estimated for IMF and BF has a high probability of success.

Performance and carcass traits of Nellore and Red Norte steers finished in feedlot

Objetivou-se avaliar o ganho medio diario (GMD) e as caracteristicas de carcaca em novilhos das racas Nelore e Red Norte, nao-castrados, terminados em confinamento e avaliar as predicoes do desempenho pelos sistemas CNCPS 5.0, NRC (2000) e BR-CORTE. Utilizaram-se 41 novilhos: 19 do grupo Nelore com peso vivo inicial de 361 ± 31 kg e 22 do grupo Red Norte com peso vivo inicial de 367 ± 30 kg. O periodo de adaptacao teve duracao de 28 dias. A avaliacao do desempenho animal foi composta de tres periodos de 28 dias, totalizando 84 dias. Ao final de cada periodo, realizou-se a pesagem dos animais apos jejum alimentar de 16 horas. Na raca Red Norte, o ganho medio diario foi superior ao da raca Nelore (1,81 vs. 1,43 kg/dia). Os animais da raca Red Norte apresentaram tambem maior area de olho-de-lombo (75,41 cm2 vs. 68,67 cm2). Nao foi observada diferenca nas espessuras de gordura subcutânea e de gordura na garupa entre os grupos geneticos. Nenhum dos sistemas de exigencias nutricionais avaliados foram eficientes para a predicao do desempenho animal. Na raca Nelore, o ganho medio diario observado foi de 1,53 kg/dia, com valores preditos de 1,53; 1,70 e 1,82 kg/dia pelos sistemas NRC, CNCPS e BR-CORTE. Apesar de os valores medio e preditos pelo sistema NRC terem sido semelhantes, de acordo com a equacao de regressao, o intercepto e a inclinacao foram diferentes de zero e um. Na raca Red Norte, o desempenho observado foi de 1,88 kg/dia com valores preditos de 1,50; 1,66 e 1,72 kg/dia pelos sistemas NRC, CNCPS e BR-CORTE, provavelmente porque o banco de dados desses sistemas e baseado principalmente em resultados obtidos em bovinos Angus.