M. A. Silva

Uso de redes neurais artificais na predição de valores genéticos para peso aos 205 dias em bovinos da raça Tabapuã

Data from 19,240 Tabapua animals from 152 farms located in different states of Brazil, born from 1976 to 1995, were used to predict the genetic value of body weight at 205 days of age (BV_P205) of Tabapua beef cattle using Artificial Neural Networks (ANN) and LM algorithm - Levenberg Marquardt training for data entry. Due to the use of networks with supervised learning, the predicted breeding values for P205 from BLUP were used as desired output. The breeding values for P205 obtained from RNA and those predicted by BLUP were highly correlated. The ranked breeding values for body weight at 205 days through RNA and those predicted by BLUP (VG_P205_RNA) showed a variation in the classification of animals indicating risks in the use of ANNs procedure for genetic evaluation of this trait. Insertions of new animals require new training data always dependent on BLUP.

Efeito da interação idade da matriz x peso do ovo sobre o desempenho de codornas de corte

The effect of female breeder age x egg weight interaction was evaluated on the performance of meat type quails (Coturnix coturnix coturnix) at 21st and 42nd days of age. For every female breeder age class (70, 205, and 280 days of age), 600 eggs were classified according to egg weight class (class 1: 11.0-12.9; class 2: 13.0-14.9, and class 3: 15.0-16.9g). A total of 225 quails of both genders, totaling 75 quails for every egg weight class were used in this study. A completely randomized experimental design with five replicates of 15 quails was used. The experimental diets were formulated to contain 28% crude protein and 2,900 kcal of metabolizable energy (ME). Weight gain, body weight, feed consumption, and weight gain: feed consumption ratio from hatch to 21st day and from hatch to 42nd day of age were recorded. Both egg weight and female breeder age classes affected body weight, weight gain, and feed consumption at 21st and 42nd days of age. Quails from heavier egg weight class and female breeder age classes 205 and 280 days of age showed higher performance (P<0.05). Quail viability was affected by egg weight class, i.e. quails from lighter eggs showed lower viability at 21st and 42nd days of life. Heavier eggs originated heavier quails at hatch (P<0.05)

Seleção e classificação multivariada de modelos de crescimento não lineares para bovinos Nelore

This study aimed to evaluate cluster analysis in classifying and selecting non linear models to describe Nelore beef cattle growth based on different goodness of fit criteria tests. A total of 12 non linear models were evaluated based on the following criteria: the determination coefficient (R2), error mean square (QME), Akaike information criterion (AIC), Bayesian information criterion (BIC), mean quadratic error of prediction (MEP) and predicted determination coefficient (R2p). The Brody model showed the best adjustment for the data set.

Avaliação da persistência na lactação da raça Guzerá, utilizando modelos de regressão aleatória

The heritability and the genetic and permanent environment correlations were estimated among six different measures of persistency in the lactation of Guzerat cow, using the Random Regression Model. A total of 8,403 records from 1,034 first lactation cows were evaluated. The Random Regression Model was calculated by the logarithmic function of Ali and Schaeffer and Legendre polynomials to get coefficients for fixed, additive genetic and permanent environment effects. Ali and Schaeffer was the function that better fit to the data, but it had convergence problems. The results showed that persistence is a trait with moderate heritability, and low correlation with genetic value for 305-d milk production which allows to select animals in order to alter the format of the curve of production without affecting the total productivity. The measure of persistence that calculates the difference of milk production between the medium and initial phases was highly correlated with 305-d milk production.

Níveis de metionina + cistina para características de desempenho e de carcaça em codornas de corte EV2

Methionine + cystine requirements for meat type quails during the growing phase were evaluated in a completely randomized experimental design with five levels of methionione + cystine (.73, .79, .85, .91, .97, and 1.03%), and five replicates of 13 quails per experimental unit. Body weight (g), weight gain (g), feed intake (g), and feed: weight gain ratio were recorded for each experimental period (from seven to 21 days and seven to 42 days of age). At 42 days of age, four quails (two males and two females) were randomly sampled from each experimental unit, slaughtered after a jejunum of eight hours to evaluate weights and yields of carcass relative to live body weight and yields of main cuts (breast and thigh), edible giblets (liver, gizzard, and heart) and abdominal fat relative to carcass weight (without foot and head). Methionine + cystine levels showed quadratic effects on body weight and weight gain at 21 days of age, with estimated maximum performances for quails fed .95% methionine + cystine level, while feed:weight gain ratio decreased with the increasing level of these amino acids. Significant and linear effects of methionine + cystine on body weight were observed at 42 days of age on weight; and on weight gain and feed intake from seven to 42 days of age. No significant effects of methionine + cystine were observed for live body weight, weights and yields of breast, thigh, abdominal fat, liver, gizzard, and heart. Higher body weight, eviscerated carcass, thigh, breast, abdominal fat, gizzard, and liver weight and yield were observed for females, while males showed higher eviscerated carcass weight. The highest weight gains were observed for EV2 quails fed .95% methionine + cystine from 7th to 21st days of age and from 7th to 42nddays of age corresponding to a methionine + cystine: lysine ratio of .73% and .79% and to a daily methionine + cystine intake of .134 and .234g/quail, respectively.

Exigência de metionina + cistina para codornas de corte durante a fase de crescimento

The effect of the methionine+cystine level on the performance of European quail during two phases in the growing period (from hatch to 21 days of age and from hatch to 35 days of age) was evaluated in a completely randomized experimental design with six levels of total methionine+cystine (.73; .79; .85; .91; .97 and 1.03%), and four replicates and 12 quails per experimental unit. Body weight, weight gain, feed intake and feed:weight gain ratio were evaluated in both phases. Significant and quadratic effects of methionine+cystine on the performance traits recorded from hatch to 21 days of age were observed. The highest body weight and weight gain and lowest feed intake and feed:weight gain ratio were estimated for quails fed .95% and .94% diets. Significant and quadratic effects of metionine+cystine on body weight, weight gain and feed intake from hatch to 35 days of age were estimated for quails fed .93%; .93%; and .94% diets, respectively. Weight gain methioninine+cystine requirement from hatch to 21 days is .95%, and from hatch to 35 days of age is .93%.

Determinação da energia metabolizável e balanço de nitrogênio de dietas com diferentes teores de proteína bruta para frangos de corte

A metabolism trial was carried out in metabolic cages in a completely randomized experimental design to evaluate the effect of CP reduction on nutrients and energy digestibility in the diets of broiler chickens. A hundred sixty male broiler chickens were randomly allotted to four treatments (CP levels) and four replicates of 10 birds each. The crude protein levels used in the diets were 21, 19, 17 and 15. The total excreta was colleted and recorded from 25 to 29 days of age. The CP reduction improved dry matter and energy digestibility linearly. A quadratic effect of the CP level on CP digestibility was observed. The maximum digestibility was estimated for broilers fed 15.3% CP diets. The nitrogen intake and excretion decreased linearly with the CP reduction. The maximum retained nitrogen and nitrogen efficiency utilization were estimated for broilers fed 18.3 and 15.3% CP diets, respectively. No effect of CP levels on ME was observed.

Efeito da redução da proteína bruta e da suplementação de aminoácidos para suínos machos castrados, dos 70 aos 100kg

This experiment was carried out to evaluate the influence of crude protein (CP) reduction level of diet with amino acid supplementation on performance of barrows. A total of 48 crossbred barrows, with average initial weight of 70.12±1.56kg were used. The animals were allotted in a completely randomized experimental design with four treatments, 17.95; 16.45; 14.95; 13.45%CP, six replicates and two animals per experimental unit. The barrows were fed ad libitum during the experiment. No effect of decreasing dietary CP level on feed intake and weight gain was observed. There was a quadratic effect of the CP levels on feed:gain ratio with minimum estimated value for barrows fed 15,70% CP diet. There was no effect of CP levels on backfat thickness and lean meat. Reducing CP level from 17.95 to 13.45% in barrows diet with amino acids supplementation has no harmful effect on the performance and carcass characteristics.

Utilização de modelos de norma de reação com variância residual heterogênea para estudo de valores genéticos de peso de codornas de corte em função de níveis de proteína bruta na dieta

The sensitivity of genetic values for body weight of meat type quails predicted at 21 and 35 days of age under diets with different crude protein levels was evaluated. Data from subjects belonging to two strains (EV1 and EV2) were used to fit a random regression model under heterogeneity of residual variance assumption. The random regression coefficients for intercept (bo) and slope (b1) were positively correlated in all analyses results, but the correlation was higher in the EV2 data analyses for both ages. Results indicated that additive genetic variance and heritability change as a function of the environment gradient for both genetic strains and ages. The reaction norms for EV1 strain suggest there is genotype by environment interaction (G x E) for both ages as there were remarkable changes in the ranking of body weight breeding values for different crude protein levels. Furthermore, changes in the magnitude of the genetic effects dispersion as a function of protein level of diet indicates there is G x E in EV1 and EV2 strains. Therefore, the prediction of breeding values for body weight of quails under a specific level of crude protein in the diet does not hold for different environments regarding the level of this nutrient.

Efeito da ractopamina e de métodos de formulação de ração sobre o desempenho e as características de carcaça de leitoas em terminação

The effect of ractopamine supplementation and feed formulation methods was evaluated on performance and carcass characteristics of finishing gilts. Sixty animals were allotted in a completely randomized block experimental design, in a 2x3 factorial scheme - ractopamine (0 and 5ppm) X three feed formulation methods. Interactions between feed formulation method and ractopamine for daily weight gain (DWG), body weight, feed:gain (DFG), and lean carcass meat deposition (LCMD) were by in vivo carcass evaluation using ultrasound observed. Daily feed intake (DFI), lysine intake (DLI), DWG, and final body weight were higher for diets with high protein level. Ractopamine supplementation did not affect feed intake, and lysine intake, but increased daily weight gain. Feed formulation method affected carcass characteristics recorded at 28 days, while ractopamine supplementation reduced backfat thickness, increased muscle depth, and lean carcass proportion of the gilts. Ractopamine improved performance and carcass characteristics of finishing gilts and feed formulation methods affected performance and carcass characteristics. Better performance and higher lean carcass deposition were observed for finishing gilts fed high protein level diets supplemented with ractopamine.