Características reprodutivas e suas associações com outras características de importância econômica na raça Nelore / Reproductive traits and their associations with other economically important traits in Nelore

Objetivou-se com este trabalho estimar as herdabilidades (h²) e as correlações genéticas (r g) entre idade ao primeiro parto (IPP) e primeiro intervalo de partos (PIEP) e outras características como peso (PS) ao ano (A) e ao sobreano (S), altura do posterior (ALT) e perímetro escrotal (PE450) em animais da raça Nelore. Os parâmetros genéticos foram estimados em uma análise multicaracterística por modelo animal, utilizando-se a inferência bayesiana via algoritmo de "Gibbs Sampling". Os parâmetros genéticos estimados sugerem a existência de variabilidade genética para IPP (h² = 0,26), sendo que a seleção para a diminuição da IPP de fêmeas Nelore deve responder à seleção individual, sem causar antagonismo do valor genético dos animais para PS (r g = -0,22 (A) e -0,44 (S)) e PE450 (r g = 0,02). A seleção para a diminuição da IPP, no longo prazo, pode levar a um aumento da ALT dos animais, embora essa associação seja relativamente baixa (-0,35). A estimativa de herdabilidade a posteriori para a característica PIEP foi baixa, 0,11±0,03. As r g entre PIEP e as demais características estudadas indicam que a seleção para essas características de crescimento não afetará o PIEP.

Heritability (h²) and genetic correlations (r g) were estimated between reproductive traits such as age at first calving (AFC), first calving interval (FCI) and other economically relevant traits, i.e., weight (W) at year (Y) and at 18 months of age (S), scrotal circumference (SC), and hip height (HH) in Nelore cattle. The genetic parameters were estimated in a multiple-trait analysis, with animal models using the Bayesian inference by Gibbs Sampling algorithm. The genetic parameters estimated in this work suggest the existence of genetic variability for AFC (h² = 0.26), where the selection for the reduction of Nelore females AFC should respond to mass selection, without causing genetic antagonism in the selection of W (r g = -0,22 (Y) and -0,44 (S)), and SC (r g = 0,02). The selection for the AFC in the long term could lead to an increase in the animal's frame, although this association is relatively low (-0.35). The posteriori heritability estimate for FCI was low, 0.11±0.03. The r g between FCI and the other traits studied indicate that selection for these growth traits will not affect the FCI.

Avaliaçöes ultra-sonográfica, macroscópica e histológica da biopsia testicular em ovinos / Assessment of ultrasonographic images and gross and microscopic lesions of the testicular biopsy in sheep

Devido ao fato da biopsia testicular poder acarretar hemorragia, inflamaçäo, degeneraçäo, aderência e fibrose, especialmente com as técnicas incisionais ou abertas, este trabalho avaliou a aplicabilidade de uma técnica menos invasiva (biopsia com agulha Tru-Cut) em ovinos na obtençäo de material para histologia e acompanhou as lesöes testiculares posteriores. Trinta carneiros foram igualmente divididos em três grupos: 1) controle, animais näo submetidos à biopsia; 2) submetidos à biopsia + cola de fibrina nos locais da biopsia testicular e incisöes da pele; e 3) submetidos à biopsia + sutura da pele escrotal após a biopsia. Exames ultra-sonográficos foram realizados pré e pós biopsia. No centésimodia, os testículos foram avaliados macro e microscopicamente após orquiectomia. A ultra-sonografia permitiu mapear as alteraçöes ocorridas e acompanhar a evoluçäo das seqüelas. Ao exame macroscópico, pequenas áreas de calcificaçäo foram observadas em 55 e 70 por cento dos testículos nos grupos 2 e 3, respectivamente. A biopsia com agulha Tru-Cut forneceu material suficiente para histologia mas ocasionou lesöes focais restritas à área biopsiada. Apesar da possível ocorrência de calcificaçäo e outras lesöes mínimas, foi demonstrado que a biopsia com agulha Tru-Cut em ovinos é um procedimento seguro por näo ter comprometido significativamente as características estruturais e funcionais dos testículos

Effect of gamma irradiation on the behavioral properties of crotoxin

Crotoxin has been detoxified with gamma radiation in order to improve crotalic antiserum production. Nevertheless, present knowledge of the biological characteristics of irradiated crotoxin is insufficient to propose it as an immunizing agent. Crotoxin is known to increase the emotional state of rats and to decrease their exploratory behavior (Moreira EG, Nascimento N, Rosa GJM, Rogero JR and Vassilieff VS (1996) Brazilian Journal of Medical and Biological Research, 29: 629-632). Therefore, we decided 1) to evaluate the effects of crotoxin in the social interaction test, which has been widely used for the evaluation of anxiogenic drugs, and 2) to determine if irradiated crotoxin induces behavioral alterations similar to those of crotoxin in the social interaction, open-field and hole-board tests. Male Wistar rats (l8O-220 g) were used. Crotoxin (100, 250, and 500 mug/kg) was injected intraperitoneally 2 h before the social interaction test. Similarly, irradiated crotoxin (2000 Gy gamma radiation from a 60Co source) was administered at the doses of 100, 250, and 500 mug/kg for the hole-board test, and at the doses of 1000 and 2500 mug/kg for the open-field and social interaction tests. ANOVA complemented with the Dunnett test was used for statistical analysis (P<0.05). Crotoxin decreased the social interaction time(s) at the doses of 1OO, 250 and 500 mug/kg (means + SEM) from 51.6 ñ 4.4 to 32.6 ñ 3.7,28.0 ñ 3.6 and 31.6 ñ 4.4, respectively. Irradiated crotoxin did not induce behavioral alterations. These results indicate that 1) crotoxin may be an anxiogenic compound, and 2) in contrast to crotoxin, irradiated crotoxin was unable to induce behavioral alterations, which makes it a promising compound for the production of crotalic antiserum.

Crotoxin-induced behavioral effects in rats

Crotoxin is the major component of Crotalus durissus terrificus venom. In view of the presence of high-affinity specific binding sites for crotoxin in the brain, the objective of this work was to investigate whether crotoxin induces behavioral effects in the open-fleld and hole-board tests. Adult male Wistar rats (l80-220 g) treated with crotoxin, 1OO, 250 and 500 mug/kg, ip, administered 2 h before the test, presented statistically significant behavioral alterations (ANOVA for one-way classification complemented with Dunnet test, P<0.05). In the open-field test, 250 and 500 mug/kg of crotoxin increased freezing (from 3.22 sec to 10.75 sec) and grooming (from 13.44 sec to 22.75 sec and 21.22 sec) and decreased ambulation (from 64.8 to 39.38 and 45.8). The dose of 500 mug/kg also decreased rearing (from 24.9 to 17.5). In the hole-board test, 500 mug/kg of crotoxin decreased head-dip count (from 6.33 to 4.00). All the crotoxin- induced behavioral effects were antagonized by an anxiolytic dose of diazepam (1.5 mg/kg, ip, 30 min before the tests). These results show that crotoxin reduced open-field activity and exploratory behavior as well. We suggest that these effects express an increased emotional state induced by this toxin.