Victor Breno Pedrosa

Curvas de crescimento de cordeiros da raça Ile de France criados em confinamento

The objective of this study was to evaluate the nonlinear models that best describe the growth curve of ram lambs Ile de France created in intensive system in the state of Parana. Therefore, there were weighed fortnightly during the period from February 2013 to June 2013, from birth to slaughter (120 days) of 31 Ile de France ram lambs. Growth curves were obtained by nonlinear models Brody, Von Bertalanffy, Gompertz and Logistic in which parameters were considered maturation rate (K), asymptotic weight (A), age of the animal (t) is given by integration determining the proportion of growth after birth (B) and the proportion of asymptotic value at which the inflection point occurs curve (m) in accordance with the adopted model. The parameters were estimated by Marquardt applied to the NLIN procedure of SAS statistical program and the criteria used to verify the accuracy of the fit of the curves were the mean square of the coefficient of determination. The Brody, Von Bertalanffy, Gompertz and Logistic resulted respectively in 26.4579; 26.1668; 26.136; 26.1582 for the mean square and 0.813; 0.958; 0.958; 0.958 for the coefficient of determination. Considering the criteria assumed the Gompertz model, followed by Logistic and Von Bertalanffy, presented the best fit to describe the growth of Ile de France ram lambs.

Estrutura populacional de rebanho fechado da raça Nelore da linhagem Lemgruber

The objective of this work was to determine the population structure and the effects caused by inbreeding in a closed herd of Nellore cattle of the Lemgruber line. The pedigree file included records of 39,290 animal, 17,646 males and 21,644 females, born between 1951 and 2007. The population structure was analysed using the software Poprep and Endog, which resulted in some level of inbreeding for 61,82% of the animals. The average F value was 3.02% for the whole population and 4.89% for the inbred animals; and F maximum value was 37.5%. The number of ancestors that contributed to the reference population was 2,380 animals, from which only seven explained 50% of the genetic variability of the population. The effective number of founders (Nf) and the effective number of ancestors (Na) in this population were, respectively, 25 and 21. The expected increase of inbreeding, caused by the unbalanced contribution of founders, was 1.62%. The herd populational structure shows the aging of the breeders, with a consequent increase of the generations interval, as well as a continuous increase of inbreeding and a high percentage of inbred individuals. Such facts compromise the annual genetic gain and should deserve a closer attention from breeders.

Growth Curves of Texel Male Lambs

Background: The consumption of lamb meat is growing due to improved farming methods. However, to be economically feasible, the animal should stand out for its precocity, fast finishing and muscular force, such as seen in Texel breed. Besides, knowledge about weight gain and development can facilitate the selection of the best animals, and allow a better fitting to farming systems. Growth curves are an effective method that describes animal development, modeling the relationship between weight and age and help to predict the growth rate. Thus, this study aimed to analyze which nonlinear model, including Brody, Gompertz, Von Bertalanffy and Logistic best describe the growth curve of Texel sheep. Materials, Methods & Results: In this experiment, the lambs were kept in confined system while the ewes, in a semi-extensive system. This study followed 42 Texel male lambs, which were confined from birth to slaughter, and fed concentrated feed (3% of body weight) and corn silage (average 1.5 kg/animal/day), 4 times a day. The lambs were weighed fortnightly, in different classes considered as follows, weight at birth (BW), 15 days (P15), 30 days (P30), 45 days (P45), 60 days (P60), 75 days (P75), 90 days (P90), 105 days (P105), and 120 days (P120), which was defined as the slaughtering weight. The growth curves were determined using the nonlinear models of Brody, Von Bertalanffy, Gompertz and Logistic. The following parameters were used in the curves, Y, slaughtering weight; A, asymptotic weight; k, growth rate, t, animal age; B, constant related to the initial weight; and, m, constant of the curve shape. The criteria used for selecting the model that best described the curve were the mean square error (MSE), which was calculated by dividing the sum of squared error by the number of observations, and also the coefficient of determination (R²), calculated as the square of the correlation between the observed and estimated weights. The average weights observed were as follows, 4.02 kg at birth, 21.68 kg at weaning (P60) and 32.55 kg at slaughtering (P120). The solution of the nonlinear models allows, thru the parameters, establish specific feeding programs and define the optimal slaughtering age. Furthermore, the coefficients of determination, with values close to 97.3%, showed good fits for all models. Still, considering the mean square error, where the lower value indicates the best fit to the data evaluated, the results were 13.1564 (Brody), 13.3421 (Von Bertalanffy), 13.4876 (Gompertz) and 13.6717 (Logistic). The results showed that Brody could be considered the model that best describes the growth rate up to 120 days old of Texel lambs. Discussion: Compared to other studies, the average weights obtained in the experiment varied widely. This large variation can be explained by the used rearing system that might favor or not the performance of lambs. However, the average weaning weight obtained was similar to several studies in the literature, confirming the potential of Texel breed. This breed demonstrated to be capable to provide a precocious animal, with good growth results from the early developmental stage until the slaughtering age. Regarding the growth curves, the Brody model was the best fit for the estimated and observed weights. Moreover, the coefficient of determination indicated good fits for all models. However, an important aspect is the negative correlation between the A and k parameters, demonstrating that the higher the animal growth rate, the lower its asymptotic size.

Evaluation of genotype by environment interactions on milk production traits of Holstein cows in Southern Brazil

Objective This study assessed the possible existence of genotype by environment interactions for milk, fat and protein yields in Holstein cattle raised in one of the most important milk production basins in Brazil. Methods Changes in the genetic parameters and breeding values were evaluated for 57,967 animals from three distinct regions of southern Brazil, divided according to differences in climate. The genotype by environment interaction was determined by genetic correlations between regions, estimated by the restricted maximum likelihood, considering the animal model. Bull rankings were investigated to verify the ratio of coincident selected animals between regions for each trait. Results The estimates of heritability coefficients were similar between two regions, but were lower in the third evaluated area, for all traits. Genetic correlations between regions were high, ranging from 0.91 to 0.99 for milk, fat and protein yields, representing the absence of a genotype by environment interaction for productive traits. The percentage of selection error between regions for the top 10% of animals ranged from 0.88% to 2.07% for milk yield, 0.99% to 2.46% for fat yield and 0.59% to 3.15% for protein yield. Conclusion A slight change in genotype between areas was expected since no significant genotype by environment interactions were identified, facilitating the process of selecting Holstein cattle in southern Brazil.

No effects of homeopathy on somatic cell count, bovine milk yield and composition

This study aimed to evaluate the effect of a homeopathic complex, on the reduction of milk somatic cell count, production of milk, fat percentage and protein percentage of milk in lactating Holstein cows, over a period of three months. Twenty cows, in second parity, were randomly assigned in blocks with two treatments, after an initial period of adaptation in the experimental area for 15 days. The cows were distributed into a control group (that did not receive the homeopathic complex) and a treated (that received the homeopathic complex), evaluated for six test-day records. Laboratory analysis of fat and protein were made via the infrared absorption and somatic cell count by flow cytometry, wherein this latest has been transformed into logarithmic scale for statistical analysis. Analysis of variance to test the effects of treatment, test-day record and the interaction between these factors, was performed through repeated measures over time. For all traits, there was no significant interaction between treatment and test-day record (p > 0.05) and there was no statistical difference (p > 0.05) between the control and treated groups. The use of the homeopathic complex was not effective in reducing somatic cell count of dairy cows, for the trial period of three months. The use of homeopathy did not interfere significantly with milk yield or the protein percentage in Holstein cows.