Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.

Com o objetivo de estabelecer os valores de referência do eritrograma de bovinos da raça Jersey, criados no Estado de São Paulo, e avaliar a influência exercida pelos fatores etários realizaram-se exames em amostras de sangue colhidas de 253 fêmeas clinicamente sadias (não reagentes ao antígeno glicoprotéico gp 51 da cápsula do vírus da leucose dos bovinos). Nas amostras de sangue, que continham EDTA como anticoagulante, foram realizadas as seguintes provas: contagem do número de hemácias em câmara de Neubauer modificada, utilizando líquido de Gower como diluidor; determinação do volume globular pelo método do microematócrito; dosagem de hemoglobina pelo método de cianometaemoglobina e cálculo dos índices hematimétricos absolutos (volume corpuscular médio - VCM, hemogloina corpuscular média - HCM, concentração de hemoglobina corpuscular média - CHCM). Observou-se influência dos fatores etários sobre os valores do eritrograma, sendo o número de hemácias e o volume globular significativamente maiores nos animais jovens, enquanto que os teores de hemoglobina não variaram em função da idade. Os valores de referência para o número de hemácias, volume globular e hemoglobina foram, respectivamente, 6,62±1,47 células × 10(6)/mm³, 31,6±3,5% e 10,45±1,29 g/dl. Os resultados médios dos índices hematimétricos absolutos aumentaram com o desenvolvimento etário, sendo os valores de referência para o VCM, HCM e CHCM, 49,18±8,28mim³; 16,37±3,37pg e 33,14±2,57%, respectivamente.

Eight BLV-seropositive female cattle presenting persistent lymphocytosis associated with BLVinfection were submitted to cytogenetic analysis. As a control group, six BLV-seronegative females, from the same herd, with no haematological or clinical changes were used. The affected group revealed a significant increase in the proportion of aneuploid cells with chromosome aberrations. An immunological assay revealed that the cells presenting the chromosomal aberrations were from the B cell population. The question of a direct or indirect action of the virus on the chromosomes in causing these changes is discussed.

Economic losses caused by enzootic bovine leukosis (EBL) have been of interest since World War II, when the neoplastic form of EBL increased dramatically in Europe. Olson (1974) and House et al. (1975) showed that animals with lymphosarcoma caused by the bovine leukosis virus (BLV) had reduced milk yields, a less efficient reproductive performance and high veterinary costs and mortality rates, while many carcasses were rejected at slaughter. However, the actual impact of BLV infection in cattle without lymphosarcoma is not clear. The purpose of the study reported here was to compare some productive and reproductive responses of cattle that were antibody-positive (BLVj) or negative (BLVk) for BLV.Holstein dairy cows in commercial dairy farms were used in this study. Blood samples were collected and subjected to BLV serological examination by the agar gel immunodiffusion test of Miller & van der Maaten (1976). Animals were then grouped as BLVj or BLVk according to their serological response to the BLV antigen. Productive and reproductive histories were obtained from individual animal records and the following factors were considered : milk production, calving interval and birth rate. For milk production, we had the daily milk yields of 547 animals, and for calving interval the time between two successive parturitions for 444 cows. These values were examined by ANOVA and when this was significant a Student's t test was carried out for each age group. Birth rates, the percentage of animals that calved in 1 year, were available for 557 animals and were examined with the Z-two proportion test. For all analyses, P 0n05 was considered significant.   Mean daily milk yield was lower by 11 % in BLVj than in BLVk cattle (19n4 v. 21n8 kg ; Table 1) and this was significant or approached significance for some age groups. This agrees with the findings of Reinhardt et al. (1988) and Brenner et al. (1989), who found decreases in milk yield of 3 and 3n5 % respectively. However, Langston et al. (1978), Huber et al. (1981) and Burridge et al. (1982) found no differences in the milk production of BLVj and BLVk cattle.No differences were found in the reproductive characteristics investigated (calving interval and birth rate ; see Tables 2 and 3). These results agree with the observations of previous workers (Langston et al. 1978 ; Huber et al. 1981 ; Brenner

O objetivo foi avaliar os aspectos produtivos e reprodutivos, de caprinos leiteiros, reagentes e não reagentes à prova de imunodifusão em ágar gel (IDAG), utilizando os antígenos gp135 e p28 do vírus da Artrite Encefalite Caprina (CAE). Os animais pertenciam a uma propriedade localizada no interior de São Paulo e foram acompanhados por um período de 24 meses, tendo sido realizados 3 testes sorológicos, com intervalos de 12 meses. A freqüência de ocorrência da CAE, nos três momentos foi respectivamente, 60,1%, 74,1%, e 70,5% (média de 68,3% - 566/829). O percentual de animais reagentes aumentou significativamente com a idade. A duração média da lactação (dias) foi menor para reagentes e significativa nas faixas etárias 24 a 36 meses e 36 a 48 meses. A produção leiteira (kg./dia) foi menor para reagentes e significativa nas faixas etárias: 12 a 24 meses maior ou igual a 48 meses. A produção total por lactação foi 21,5% menor para as cabras soropositivas. A CAE não influenciou os aspectos reprodutivos neste estudo no que se refere à idade ao primeiro parto, ao intervalo interpartos. No entanto, a média de idade ao parto entre os animais reagentes foi maior e estatisticamente significante e o peso das crias nascidas de mães reagentes com idade maior ou igual a 48 meses foi menor do que os animais nascidos de cabras não reagentes.