Leandro Lunardini Cardoso

Hierarchical Bayesian models for genotype × environment estimates in post-weaning gain of Hereford bovine via reaction norms

It was evaluated statistical models with different assumptions to define the one that best describes the presence of genotype × environment interaction on adjusted post-weaning weight gain (PWG345) of Hereford cattle, through the study of reactions norms to the environment, obtained by random regression using a Bayesian approach. Four reaction norms hierarchical models (RNHM) were used through the INTERGEN program. The RNHMK uses the solutions of contemporary groups previously estimated by the standard animal model (AM) and considers them as environmental level for predicting the reaction norms and the RNHMS, which jointly estimate these two sets of unknowns. For both models, two versions were considered, one with a homogeneous (hm) and another with a heterogeneous (ht) residual variance. Based on the deviance information criterion and Bayes factor, RNHMshm showed the best fit to the data, and by the deviance based on conditional predictive ordinate, the best fit was the RNHMKht, whereas, by all the three criteria used, the worst fit was obtained by using the standard animal model. Heritabilities estimated on RNHM were increasing in the environmental gradients for PWG345, at -60 kg, 0 and +60 kg. The genetic correlation estimated between the level and slope of reaction norms was high, from 0.97 to 0.99, characterizing a scale effect on genotype × environment interaction. The reaction norms hierarchical models are efficient to describe the changes in variance components due to the environment and to describe the presence of genotype × environment interaction on PWG345 trait of Hereford cattle.

Genetic parameters for production traits in primiparous Holstein cows estimated by random regression models

The objective of this study was to estimate genetic parameters for milk, fat and protein yields of Holstein cows using 56,508; 35,091 and 8,326 test-day milk records from 7,015, 4,476 and 1,114 cows, calves of 359, 246 and 90 bulls, respectively. The additive genetic and permanent environmental effects were estimated using REML. Random regression models with Legendre polynomials from order 3 to 6 were used. Residual variances were considered homogeneous over the lactation period. The estimates of variance components showed similar trends, with an increase of the polynomial order for each trait. The heritability estimates ranged from 0.14 to 0.31; 0.03 to 0.21 and 0.09 to 0.33 for milk, fat and protein yield, respectively. Genetic correlations among milk, fat and protein yields ranged from 0.02 to 1.00; 0.34 to 1.00 and 0.42 to 1.00, respectively. Models with higher order Legendre polynomials are the best suited to adjust test-day data for the three production traits studied.

Estimativas de Rendimentos de Cortes Comerciais e de Tecidos de Suínos em Diferentes Pesos de Abate pela Técnica de Ultra-sonografia em Tempo Real 1

Forty-eight female pigs slaughter at 50, 60, 70, 80, 90, 100, 110 and 120 kg were used to determine commercial cut and of lean meat yields in pork carcass, with a view of the Longissimus muscle area and backfat thickness estimation by using the real-time ultrasound technology. Live ultrasonic measurements were taken for Longissimus muscle area and for backfat thickness and measures in the hot carcass were made, using optical Henessy equipment, to estimate the backfat thickness and Longissimus muscle depth. The regression equations to estimate the amount of muscle in the carcass obtained a R2 between 0.97 and 0.99, with a residual standard deviation (RSD) between 0.27 and 0.73. The R2 values for Longissimus muscle area obtained by ultrasound and for backfat thickness direct in the carcass, were 0.97 and 0.98, respectively, with a RSD of 3.07 and 3.13. The adjustment of the regression equations for ultrasound backfat tickness, for optical backfat tickness and for directly carcass backfat tickness measurement, presented R2 of 0.99, 0.82, and 0.86, respectively, with a RSD of 2.39, 3.13, and 2.91. The fitted regression equations obtained by simple and multiple linear regressions from the dissection data set were precise to estimate commercial cuts and of lean meat of pork carcasses between 50 and 120 kg. The real-time ultrasonograph technology is accurate to estimate the Longissimus muscle area and backfat tickness in live animal.

Persistence in milk, fat and protein production of primiparous Holstein cows by random regression models

Total numbers of 56,508, 35,091 and 8,326 records of milk, fat, and protein test-day yields, respectively, were used to estimate genetic parameters for six persistency measures on milk, fat and protein productions of Holstein cows reared in Minas Gerais state. Covariance components for additive genetic effects and permanent environmental effects were estimated by REML in random regression models using Legendre polynomials from the third to the sixth order. Overall, models with the highest orders of Legendre polynomials showed the best quality of adjustments of these productive records. Heritability estimates obtained by the models for persistence in milk, fat, and protein yields ranged from 0.04 to 0.32, from 0.00 to 0.23, and from 0.00 to 0.27, respectively. Values of genetic correlation estimates between persistence and total 305-day milk, fat, and protein yields ranged from -0.38 to 0.54, from -0.39 to 0.97, and from -0.78 to 0.67, respectively. Persistence measurement proposed by Jakobsen (PS 2 ) is preferential for using in further genetic evaluations for persistence in milk, fat and protein yields of Holstein cows in Minas Gerais state.

Predição de curvas de crescimento de tecidos de fêmeas suínas por intermédio da função alométrica estendida

Abstract - Forty-eight female pigs were used to determine tissue growth curves after slaughter of the animals at 50, 60, 70, 80 , 90,100, 110 and 120 kg and dissection of the carcasses. The lean cuts in carcass were made according to that used by Brazilian p ork slaughters.In each cut it were separated muscle, fat, bone and skin amounts. The expanded allometric function was used to estimate and to fit thegrowth curves. The muscle amounts in carcass increased to 41.9% for animals at 50 kg and to 44.1% for animals at 120 kg. The ex pandedallometric function fitted the curve to muscle amount with R 2 = 0.68 and the residual standard deviation RSD = 1.82. The R 2 value forfat percentage was 0.80% and the (RSD) value was 6.35 with increase of 12.7% to 18.3% between animals at 50 to 120 kg. Concerni ngto the growth curves for the commercial meat cut yields, the R 2 value was variable, although with a RSD low. It was concluded that theexpanded allometric function is accurate to estimate swine time growth curves calculated in percentage of weight of swine, slau ghterbetween 50 and 120 kg and that fat deposition is proportionally higher than muscle deposition and that muscle and fat depositio n, inpercentage of carcass, increase from 50 to 120 kg.Key Words: expanded allometric function, growth curves, meat cuts, swine

Carcass characteristics and meat quality of Aberdeen Angus steers finished on different pastures

The present study was conducted to assess carcass features, physicochemical and sensory parameters of meat from steers finished on three types of pastures: natural pasture; natural pasture improved, fertilized and oversown with winter species; and annual summer grassland. The experiment was conducted from December 14, 2009 to November 30, 2010, with treatments distributed in a completely randomized design with a different number of replicates. Animals were used as experimental units. Experimental animals were Aberdeen Angus steers with twenty months of initial age and 354±27.4 kg of live weight, on average. The highest average daily gains were obtained for the annual summer grassland. There was no effect of treatments on carcass conformation. The highest carcass yield was obtained on the improved natural pasture. Forequarter yield, side cut yield and longissimus muscle area were similar between the pastures. Moisture and total lipids were not affected by the pasture. Thawing and cooking losses were higher in improved natural pasture and lower in sorghum pasture. Regardless of the treatment, the meat had luminosity ranging from intermediate to dark, high in red, high in yellow, and considered within the normal range for beef. Meat of higher shear force was found in natural pasture, and lower shear force was observed in meat from annual summer grassland. Average live weight daily gain explained 18% of the shear force. Sensory evaluation by duo-trio test showed differences between samples from distinct pastures in flavor. All the studied systems allow for desirable characteristics in carcass and meat.

Predição de características quantitativas de carcaças de suínos pela técnica de ultra-sonografia em tempo real

ABSTRACT - Forty-eight female pigs were used to determine the commercial cut yields after slaughter of the animals at 50, 60, 70, 80,90, 100, 110 and 120 kg and dissection of the carcasses. Life ultrasonic measures were taken to measure the longissimus muscle area and forbackfat thickness. The predictors used to estimate the lean meat yield were backfat thickness and longissimus muscle area. Bes ides the measuresmade in the different cuts, as ham cut weight, ham muscle weight, palette muscle weight, and carre muscle weight and pantry mus cle weight.Additionally, the data of the total carcass muscle weight, total carcass fat weight, total carcass bone weight and total carcas s skin weight, werealso used. Prediction equations were developed using simple and multiple linear regressions using the logistic model from the d issection dataand from the live ultrasonic measure data. Prediction equations were developed through out simple and multiple linear regressio ns using a logisticmodel from the dissection and live measures made by real-time ultrasound technology data. The prediction equation to determine the amountsthe main components of the meat pork cuts presented a great adjustment, with R