Rodolpho de Almeida Torres Filho

Ajustamento para Heterogeneidade de Variância para Produção de Leite entre Rebanhos da Raça Holandesa no Brasil

Data of 36,755 first lactation of Holstein cows, daughters of 866 sires, distributed in different states from 1980 to 1993, were stratified in herds according to the phenotypic standard deviation of the milk yield adjusted for adult age, in three levels: low (11,713 lactations), medium (12,764 lactations) and high (12,278 lactations). The total milk production adjusted for adult age and adjusted for adult age and for 305 days of lactation, within each class, and the base 10 logarithm transformations, square root, standardization and the division by class phenotypic standard deviation were analyzed. The averages of milk yield, the genetic, residual, and phenotypic variance components increased with the increase of the class mean standard deviation. The heritability did not have the same behavior, the heritability estimates of the traits of the class with high standard deviation were similar to the heritability of traits of class with low standard deviation, and both were smaller than the class with medium standard deviation, although the component of addictive genetic variance has been higher. The used transformations did not correct the existing heterogeneity of variance among the classes. The heritabilities of the unchanged characteristics varied from .25 to .35.

Fatores genéticos e de ambiente sobre o intervalo de partos de cabras leiteiras no semi-árido nordestino

The aims of this study were evaluate influence of the environmental and genetic effects on the kidding interval, using 486 records of kidding crossbred dairy goats obtained from 1988 to 1996 in Paraiba State. The environmental effects were analyzed by means of the procedure GLM of the SAS with a model that included as fixed factors the contemporary group and kidding type, and covariates age of goat at kidding and lactation length. Buck, goat inside of the buck and error were included as random effects. MTDFREML program was used in the analysis with an animal model containing the contemporary group and kidding type, the linear and quadratic effects of age of kidding and lactation length as fixed effects. Animal and permanent environmental and error were included as random effects. The least-square means of kidding interval was 275.55 ± 60.96 days. Kidding interval was affected by the contemporary group and lactation length effects. Estimates of heritability and repeatability were low, 0.09 and 0.09, respectively, showing that smaller kidding intervals would be obtained by better management.

Avaliação do consumo e de metabólitos plasmáticos de cabras gestantes com duas condições corporais alimentadas com dietas formuladas com diferentes níveis de energia

The present study evaluated the relationship between different dietary net energy (NE) levels and body condition score (BCS) on performance of dairy goats during the prepartum period. Forty-eight pregnant goats were kept in individual cages during the last 30 days before parturition. The experimental design was a completely randomized design with a 2 x 3 factorial arrangement of treatments (two BCS and three levels of NE in the diet). Goats were assigned to one of two groups, based on body condition score, which was either 3.25 or below. Prepartum diets contained 1.1, 1.4 or 1.6 Mcal NE/kg DM and 13% of CP. Blood samples were collected weekly beginning 21 days before parturition and plasma analyzed for concentration of nonesterified fatty acids (NEFA). Intakes of DM and NDF were lower in animals with greater BCS. However, intakes of DM and NE paralleled the increment of energy in the diet while the opposite was observed for NDF intake. As expected, feeding goats the low NE diet increased the plasma concentration of NEFA at day -14 and at parturition.

Tendência genética para características produtivas em bovinos da raça Pardo-Suíça

Records of 4959 lactation in 1985 to 1998 of 2414 Brown Swiss cows breed, daughters of 70 sires in 51 herds, were used to estimate the genetic trend for milk and fat yield adjusted for 305 days of lactation and mature age of cows (PL305ME and PG305ME). The genetic trend for sires was estimated using a linear regression of the breeding values of the sires to their daughters calving year, averaged to number of daughters in each calving year. The genetic trend of the cows was estimated using a linear regression of their estimates breeding values averaged to number of observation in each year of calving. The animal model used to estimate the breeding values, inclued the fixed effects of herd, year-season of calving, genetic group of the animals, and random effects of animal, permanent and temporary environment. The means of PL305ME and PG305ME were 6085.79 ± 1627.73 and 225.60 ± 60.46 kg, respectivelly. The genetic trend estimated to sires were 33.01 ± 15.27 and 1.98 ± 0,61 kg/year to PL305ME and PG305ME, respectivelly. The genetic trend estimated for cows were 20.54 ± 2.04 and .93 ± .06 kg/year para PL305ME and PG305ME, respectively.

Efeito de erros de pedigree na seleção

Data simulated with five levels of pedigree errors (0, 5, 10, 15 and 20%) and three heritabilities (.10, .30 and .60) were used to verify the effect of pedigree errors on the selection during 10 generations. The largest phenotypic values and efficiency on the individual selection, in overall, were obtained by BLUP without errors, followed by those with 5, 10, 15 and 20% of error. The average superiority in genetic gain of the BLUP per generation, in the various error levels, on the individual selection, decreased with the increase of the heritability of the trait. As the error level increased, the BLUP presented bigger reduction on the genetic gain for the traits with smaller heritabilities.

Consumo, digestibilidade e produção de leite de cabras leiteiras alimentadas com dietas contendo diferentes níveis de proteína bruta e energia líquida

Intake, digestibility of dry matter and nutrients, milk production and composition were evaluated with four isoenergetic diets containing 1.53 Mcal of net energy/kg DM and 11.4, 16.5, 19.5, and 22.6% CP. The effect of energy and PB levels were evaluated by considering the ratio of protein content and net energy concentration of the diets, obtaining values of 7.3, 10.8, 12.9, and 14.8. Eight goats were assigned to two 4 x 4 latin square design. The experimental period lasted 21 days, with 14 days for adaptation of animals and seven days for samplings. Higher DM intakes were obtained with diets with CP/NE ratio different from 7.3. The supply of the diets with lower CP/NE ratios resulted in higher intakes of NFC and EE and and reduction in TDN and NE intakes. Apparent digestibility of NFC and NDF were not altered. Higher digestibility of EE was observed when lower CP/NE ratio was used. CP digestibility decreased with the supply of diet with lower CP/NE ratio (7.3), probably due to the addition to the diet of nitrogen sources of high ruminal degradability (urea). DM digestibility differed when compared to the extreme levels of CP/NE ratio and lower in the CP/NE ratio of 7.3. Higher milk production was observed when compare 14.8 CP/NE ratio with 7.32 and 10.8 CP/NE ratio and no alteration occurred for milk components. Higher efficiency of consumed DM was obtained with diet with higher CP/NE ratio, whereas, the efficiency of N utilization in milk in relation to N intake was reduced in inverse way.

Heterogeneidade de Variância na Avaliação Genética de Reprodutores da Raça Pardo-Suíça no Brasil

Data from 6,842 lactations of 3,274 Brown Swiss cows, daughters of 71 sires, from 100 herds, calving from 1980 to 1999 were used to evaluate the effects of heterogeneity of variance on genetic evaluation of bulls. The milk and fat yields adjusted for 305 days of lactation and mature equivalent age were used to classify the herds among high and low production level. An animal model used to estimate variance component, included the fixed effect of herds, age-season of calving and grade of cows, random effect of animal, permanent environment and temporary environment. Variance components were estimated to milk (fat) yield in booth levels, considering the milk or fat yield in each production level as different trait. Estimates of heritability were .38, .38, .39 and .32 for milk and fat yields in high and low production levels, respectively. Genetic correlations between high and low production levels were .85 and .79 to milk and fat yields, respectively. In genetic evaluation programs , it is important to consider differences in variability among herds, otherwise, under selection, the most variables herds would contribute with the majority of the animals, and the genetic evaluations of the animals could be more a function not only from its genetic potential, but also from its environment where the progenies expressed their traits.

Efeito da conexidade de dados sobre o valor fenotípico médio e a variância genética aditiva

Simulated data were used to verify the effect of the connectedness on the average phenotypic value and the additive genetic variance. The simulated genome was formed from a quantitative trait governed by 500 loci. Significance herd effect (9 herds) by 5% probability F test was simulated. Data sets with 0, 15, 30, 60, 90 and 100% of connectedness for heritabilities 0.10, 0.30 and 0.60 and for different progeny sizes (9, 54 and 90 progenies/sire) were simulated. In each generation nine males were selected and the number of selected females shifted according to the number of progenies considering in each data arrange. The selection was accomplished in ten generations, where the process was repeated 30 times. Data with smaller connectedness reduced the average phenotypic value, and the largest effect of the connectedness was for small heritability and small progeny size. The connectedness effect on the additive genetic variance was small.Simulated data were used to verify the effect of the connectedness on the average phenotypic value and the additive genetic variance. The simulated genome was formed from a quantitative trait governed by 500 loci. Significance herd effect (9 herds) by 5% probability F test was simulated. Data sets with 0, 15, 30, 60, 90 and 100% of connectedness for heritabilities 0.10, 0.30 and 0.60 and for different progeny sizes (9, 54 and 90 progenies/sire) were simulated. In each generation nine males were selected and the number of selected females shifted according to the number of progenies considering in each data arrange. The selection was accomplished in ten generations, where the process was repeated 30 times. Data with smaller connectedness reduced the average phenotypic value, and the largest effect of the connectedness was for small heritability and small progeny size. The connectedness effect on the additive genetic

Efeito da conexidade de dados sobre a acurácia dos testes de progênie e performance

Simulated data were used to verify the effect of the connectedness on the accuracy of progeny and performance tests. The simulated genome was formed from a quantitative trait governed by 500 loci. Significance herd effect (9 herds) by 5% probability F test was simulated. Data sets with 0, 15, 30, 60, 90 and 100% of connectedness for heritabilities 0.10, 0.30 and 0.60 and for different progeny sizes (9, 54 and 90 progenies/sire) were simulated. In each generation nine males were selected and the number of selected females shifted according to the number of progenies considering in each data arrange. The selection was accomplished in ten generations, where the process was repeated 30 times. Data with smaller connectedness reduced the accuracy of both tests and the connectedness was more important for small heritability and small progeny size. The heritability and the progeny size had larger influence in the genetic evaluation than the effect of connectedness.

Efeito da selecao erronea de machos sobre ganhos geneticos, utilizando-se simulacao

Simulated populations were used to verify the effect of errors in the selection of males in the estimates of genetic gains along ten generations of selection, using BLUP. Five levels of errors in the selection of males (0, 5, 10, 15 and 20%) and three heritabilites (.10, .30 e .60) were used. Twenty males and 200 females were selected by BLUP. After the selection of 20 males in each generation, 1, 2, 3 and 4 sires were changed by others randomly. The phenotypic values and efficiency of BLUP with errors in relation to the BLUP without errors reduced with the increase in the error level. The decrease of the genetic gains in function of the inclusion of this type of error did not, apparently, present a relationship association with heritability of the trait.