Marcelo Teixeira Rodrigues

Suplementação de lipídios em dietas para cabras em lactação: consumo e eficiência de utilização de nutrientes

The effect of different fat supplements on intake, digestibility, nitrogen balance, milk yield and efficiency of nutrient utilization was evaluated in lactating dairy goats. Twenty-four dairy goats were assigned to a completely randomized design with four treatments and six replicates/treatment. The fat supplements tested were soybean oil (SO), calcium salts of longchain fatty acids (CS) and whole soybean (WS), which contributed with 4.5% of dietary ether extract. A control diet with no added fat was also fed to the animals. Daily measurements of intake and milk yield were done from day 51 to day 138 of lactation. Intakes of DM (DMI), NDF (NDFI), TDN (TDNI), and net energy (NEI) were lower on soybean oil and whole soybean than on control and CS diets. Feeding fat supplements to lactating goats reduced digestibilities of OM, CP and TC. Digestibility of NDF was reduced by SO while that of NFC was reduced by WS. Yields of milk fat, milk protein and milk decreased when WS was fed and the feeding of all three fat supplements depressed the yield of milk lactose. No significant differences in the concentration of milk components were observed across treatments. Similarly, the net efficiency of utilization of ingested metabolizable energy for milk production (kl) did not differ among diets. The same was true for nitrogen balance and retained nitrogen.The effect of different fat supplements on intake, digestibility, nitrogen balance, milk yield and efficiency of nutrient utilization was evaluated in lactating dairy goats. Twenty-four dairy goats were assigned to a completely randomized design with four treatments and six replicates/treatment. The fat supplements tested were soybean oil (SO), calcium salts of long-chain fatty acids (CS) and whole soybean (WS), which contributed with 4.5% of dietary ether extract. A control diet with no added fat was also fed to the animals. Daily measurements of intake and milk yield were done from day 51 to day 138 of lactation. Intakes of DM (DMI), NDF (NDFI), TDN (TDNI), and net energy (NEI) were lower on soybean oil and whole soybean than on control and CS diets. Feeding fat supplements to lactating goats reduced digestibilities of OM, CP and TC. Digestibility of NDF was reduced by SO while that of NFC was reduced by WS. Yields of milk fat, milk protein and milk decreased when WS was fed and the feeding of all three fat supplements depressed the yield of milk lactose. No significant differences in the concentration of milk components were observed across treatments. Similarly, the net efficiency of utilization of ingested metabolizable energy for milk production (kl) did not differ among diets. The same was true for nitrogen balance and retained nitrogen.

Utilização de funções matemáticas no estudo da curva de lactação em caprinos

Production of low cost milk is the most relevant aspect in dairy goat systems. Therefore, studying the behavior of the lactation curve of dairy goats is important to implement animal breeding programs as well as for plan and introduce new management tools. The objective of this study was to select among mathematical models published in the literature the one that best describe the lactation curve of dairy goats. A dataset constituted of 23,502 observations of milk yield from 748 lactations of Saanen and Brown Alpine (Oberhaslis) goats was used. Estimation of the parameters was done by the non-linear regression procedure of SAS using the modified method of Gauss-Newton. Residual plot, absolute mean deviation, correlation coefficient and visual appraisal of predicted versus measured lactation curve all were used to determine the best model. The equality of parameters and the models identity of non-linear regression were used to test if the parameters of the lactation curve were similar for breed and order of lactation. Among the evaluated models, that proposed by Nelder (1966), 2 / ct bt a t Y + + = , was the best compromise for adjustment of the lactation curve of goats. Even though differences among parameters of the chosen model for different lactation and breed were observed, only one equation was used in the analysis.Production of low cost milk is the most relevant aspect in dairy goat systems. Therefore, studying the behavior of the lactation curve of dairy goats is important to implement animal breeding programs as well as for plan and introduce new management tools. The objective of this study was to select among mathematical models published in the literature the one that best describe the lactation curve of dairy goats. A dataset constituted of 23,502 observations of milk yield from 748 lactations of Saanen and Brown Alpine (Oberhaslis) goats was used. Estimation of the parameters was done by the non-linear regression procedure of SAS using the modified method of Gauss-Newton. Residual plot, absolute mean deviation, correlation coefficient and visual appraisal of predicted versus measured lactation curve all were used to determine the best model. The equality of parameters and the models identity of non-linear regression were used to test if the parameters of the lactation curve were similar for breed and order of lactation. Among the evaluated models, that proposed by Nelder (1966), , was the best compromise for adjustment of the lactation curve of goats. Even though differences among parameters of the chosen model for different lactation and breed were observed, only one equation was used in the analysis.

Estimação de parâmetros genéticos para produção de leite de cabras da raça Alpina

Foram utilizados 9.374 registros semanais de producao de leite de 302 primeiras lactacoes de cabras da raca Alpina. A producao de leite no dia do controle foi analisada por meio de um modelo animal, unicarater, de regressao aleatoria, em que as funcoes de covariâncias para os componentes geneticos aditivos e de ambiente permanente foram modeladas por meio das funcoes de Wilmink, Ali e Schaeffer e por polinomios ortogonais, em uma escala de Legendre de ordens cubica e quintica. Assumiu-se, ainda, variância residual homogenea durante toda a lactacao e heterogenea com tres e quatro classes de variância residual. Os modelos foram comparados pelo criterio de informacao de Akaike (AIC), pelo criterio de informacao Bayesiano de Schwar (BIC), pela funcao de verossimilhanca (Ln L), pela visualizacao das estimativas de variâncias geneticas, de ambiente permanente, fenotipicas e residuais e pelas herdabilidades. O polinomio de Legendre de ordem quintica, com quatro e tres classes de variâncias residuais, e a funcao de Ali e Schaeffer, com quatro classes de variâncias residuais, foram indicados como os mais adequados pelo AIC, BIC e Ln L. Estes modelos diferiram na particao da variância fenotipica para as variâncias de ambiente permanente, genetica e residual apenas no inicio e no final da lactacao. Contudo, a funcao de Ali e Schaeffer resultou em estimativas negativas de correlacao genetica entre os controles mais distantes. O polinomio de Legendre de ordem quintica, assumindo variância residual heterogenea, mostrou-se mais adequado para ajustar a producao de leite no dia do controle de cabras da raca Alpina.

Avaliação espermática e da concentração de proteínas solúveis no plasma seminal de bodes da raça Alpina em regime de monta controlada

Foram estudadas as relacoes entre a concentracao de proteinas soluveis do plasma seminal, o teste hipoosmotico, a analise fisica e morfologica do semen e o desempenho reprodutivo de bodes da raca Alpina em regime de monta controlada. O experimento foi realizado durante os meses de fevereiro a abril de 2001. Foram realizadas 40 coletas de semen em quatro reprodutores adultos em regime de monta controlada. Em todas as coletas, alem do exame fisico e morfologico do semen, foram realizados os testes hipoosmoticos, isoosmoticos e a determinacao da concentracao de proteinas soluveis do plasma seminal. Foi detectada diferenca entre os bodes na concentracao de proteinas soluveis do plasma seminal, mas nao houve diferenca no teste hipoosmotico e no numero de coberturas por prenhez. O teste hipoosmotico pode ser uma importante ferramenta para a avaliacao de semen caprino, mas a concentracao de proteinas soluveis do plasma seminal nao pode ser utilizada como parâmetro para predizer a qualidade seminal e a fertilidade de bodes da raca Alpina utilizados em regime de monta natural.

Estimação de parâmetros genéticos em caprinos leiteiros por meio de análise de regressão aleatória utilizando-se a Amostragem de Gibbs

Random regression models were used to estimate genetic parameters for test-day milk yield (PLDC) of Alpine dairy goats, implemented by Bayesian methods with Gibbs Sampling. The estimates were compared with those obtained by random regression analysis, using REML. Heritability estimates obtained by Bayesian analysis ranged from 0.18 to 0.37, while those obtained by REML ranged from 0.09 to 0.32. Genetic correlations between yields of close test days approached the unit, but decreased gradually as the interval between test days increased. Results indicated that random regression models are appropriate to model the covariance structure of PLDC and to predict genetic gains and select animals along the lactation trajectory of dairy goats. Results obtained by Bayesian and REML approaches were similar, although genetic variance and heritability estimates were slightly higher with Bayesian methods.

Influence of Insulin-like Growth Factor I (IGF-I) on the survival and the in vitro development of caprine preantral follicles

The aim of this study was to investigate the effects of the insulin-like growth factor -I (IGF-I) on survival, activation (transition from primordial to primary follicles) and growth of caprine preantral follicles cultured in vitro. Fragments of ovarian cortex were cultured for one and seven days in the absence or presence of IGF-I (0, 50 and 100ng/ml). The non-cultured and cultured tissues were processed and analyzed by histology and transmission electron microscopy. The culture for one day in a medium with 100ng/ml of IGF-I showed 86.7% of morphologically normal follicles. These results were similar (P>0.05) to the percentage of normal follicles found in the control (96.7%). It was also found that this medium increased the percentage of follicular activation (developing follicles) with one day of culture. The oocyte and follicular diameters remained similar to the control by culturing for one day in a medium containing 100ng/ml of IGF-I. The ultrastructural analysis did not confirm the integrity of the follicular fragments in a medium containing IGF-I (100ng/ml) after one and seven days of culture. In conclusion, this study demonstrated that the addition of 100 ng/ml of IGF-I in the culture medium enables the development of preantral follicles of goats with one day of culture. However, it is not sufficient to maintain the follicular integrity and the follicular survival rate after seven days of culture.

Influência da condição corporal e da concentração de energia nas dietas no periparto sobre o desempenho de cabras em lactação

Este trabalho foi realizado com o objetivo de avaliar os efeitos da interacao nivel de energia liquida (EL) nas dietas × condicao corporal (CC) no periparto sobre o desempenho de cabras nos primeiros 60 dias da lactacao e as concentracoes plasmaticas de acidos graxos nao-esterificados (AGNE) no pos-parto. Os animais foram distribuidos em delineamento inteiramente casualizado, em esquema fatorial 2 x 3 x 2 com quatro repeticoes, composto de duas condicoes corporais, tres niveis de EL (baixo, medio, alto) na dieta no pre-parto e dois niveis de EL (medio, alto) no pos-parto. Inicialmente, os animais foram separados em dois grupos, de acordo com a CC, adotando-se o valor de 3,25 como mediano. Dietas no pre e no pos-parto foram isoproteicas, com 13 e 16% de PB, respectivamente. No periodo pre-parto, os niveis de energia das dietas foram 1,1; 1,4 e 1,6 Mcal de EL/kg de MS e, no periodo pos-parto, de 1,4 e 1,6 Mcal de EL/kg de MS. A interacao CC × niveis de EL no pos-parto influenciou o consumo de FDN, de modo que cabras com menor CC consumiram mais fibra (FDN) com a reducao da concentracao de EL nas dietas. Os niveis de EL fornecidos durante o pos-parto influenciaram o consumo de nutrientes e a producao de leite, pois a presenca de niveis elevados de FDN na dieta com 1,4 Mcal EL/kg MS limitou a expressao do potencial produtivo dos animais. Nao foram observados efeitos das CC e dos niveis de EL nas dietas sobre a concentracao plasmatica de AGNE no pos-parto, indicando pequena mobilizacao de reservas de lipidios do tecido adiposo.

Aspectos produtivos da raça Pardo-Suíça no Brasil: Fatores de ajustamento, produção de leite e de gordura, e parâmetros genéticos

A study was carried on performance of the Brown Swiss cattle with the objective of estimating adjustment factors, evaluate some environment and genetics factors that affect milk and fat yields and fat percentage, and estimate genetic parameters for this productive traits. It was appraised 11,189 lactations out of 5,382 Brown Swiss cows, from 1980 to 1999, originated from 201 herds, provided by milking record service accomplished by the Brown Swiss Cattle Breeder`s Association of Brazil. Productions were adjusted by a multiplicative factors for two milkings, 305-day and production at the mature age. The estimated averages and its standard deviation and the coefficient of variation for milk and fat yield and fat percentage were, respectively, 5,791.50 ± 1,211.58 kg and 20.92%; 217.25 ± 47.36 kg and 21.80% and 3.78 ± 0.34 and 9.16%, respectively. The effects of year and season of calving, year x season of calving interaction, herd and genetic group were significant, except for season of calving on fat percentage.Heritability estimates and repeatability for milk and fat yields were 0.37 and 0.40, and 0.36 and 0.37 respectively. Genetic correlation between milk and fat yield was 0.96. The obtained results showed the need to adjustment milk and fat yields for two milkings, 305-day and production at the mature age. It was concluded that the Brown Swiss breed has a great potential for production in Brazilian dairy herds.

Modelos de regressão aleatória na avaliação da produção de leite em cabras da raça Saanen

It was used 10,238 weekly test day records from 388 first lactations of Saanen goats with the objective of comparing random regression models (RRM). Firstly, it was compared five models, whose exponential terms of Wilmink function assumed the following values: -0.0350; -0.0500; -0.0565; -0.0680 and -0.1000 (W0350, W0500, W0565, W0680 and W1000, respectively) by considering homogeneity of residual variance over the lactation period. The value -0.0500 was kept in the model W0500 whereas models W0350, W0565, W0680 and W1000 used values -0.0350; -0.0565; -0.0680 and -0.1000, respectively, replacing the value -0.0500, proposed by the original model used in dairy cattle. After choosing the best model according to ln L, homogeneity and heterogeneity for residual variance: homogeneity, two classes, three classes, four classes, five classes and six classes along the lactation were evaluated by using AIC, BIC and ln L criteria. According to criterion used, W0350 presents the best fit among the evaluated models. With regard to residual variance, the use of six classes over lactation is indicated by AIC, BIC, ln L and likelihood ratio test. Heritability estimates over lactation, for the best model, ranges from 0.07 (2nd lactation week) to 0.25 (20th lactation week).

Evaluation of persistency lactation measures of Saanen goats under random regression model

It was used 10,238 weekly milk production records on the control day from the first 388 lactations of Saanen goats on the evalution of six lactation persistency measures in order to find out which was the best fitted for using in genetic evaluations on this trait. These six evaluated measures are adaptations from those used on dairy cattle, obtained by replacing, in the formula, bovine reference values by the goat ones. The values used in the calculations were obtained from random regression models. Heritability estimates for persistency measures ranged from 0.03 to 0.09. Genetic correlations between persistency measures and milk production until 268 days ranged from -0.64 to 0.67. Because it presented the lowest genetic correlation with production at 268 days (0.14), the persistency measure PS4 obtained by the sum of the genetic values from the 41st to the 240th day of lactation as deviations of production at 40 days of lactation, is the best recommended for genetic evaluations of lactation persistence on Saanen goats. Thus, the selection of the goats with the best persistency of lactation does not change the production at 268 days. Due to the low heritability of this measure (0.03), few responses to selection are expected on this herd.