RESUMO
A vaccine containing doses ranging from 2 µg to 50 µg of integral membrane proteins from Haemonchus contortus intestinal cells (H11 and H-gal-GP complex) has been shown to be effective for lambs. A vaccine for H. contortus was tested in two-month old grazing Corriedale lambs during an eight-month trial on the outskirts of Bagé, Rio Grande do Sul, Brazil. The animals were kept in a single paddock and allocated to five similar groups according to weight, sex and faecal egg counts (FEC). Vaccinated lambs received 0, 2, 5, 10 or 50 µg of the same antigen diluted in QuilA adjuvant. Vaccine injections were given at days 0, 21, 49, 91, 133, and 175. Lambs were sampled weekly for FEC, packed cell volume (PCV), and plasma ELISA antibody titre. Lambs with PCVs ≤15 % were drenched with levamisole (7.5 mg/kg body weight) as a salvage treatment. During days 77-98 an artificial challenge was administered to increase parasite transmission. Post-artificial challenge (from day 98-217), the FEC of the vaccinated lambs were 59.3 % lower than those of the control lambs. Antigen dose correlated with changes in PCV (r = 0.387 p-value < 0.001). Vaccinated lambs also had higher PCV than controls (p < 0.001; contrast analysis). Salvage treatment was needed in 16.7 % of vaccinated lambs and 88 % of control lambs.
Assuntos
Hemoncose/veterinária , Glicoproteínas de Membrana/imunologia , Doenças dos Ovinos/prevenção & controle , Vacinas/imunologia , Animais , Anti-Helmínticos/administração & dosagem , Anti-Helmínticos/uso terapêutico , Relação Dose-Resposta Imunológica , Fezes/parasitologia , Hemoncose/prevenção & controle , Haemonchus , Levamisol/administração & dosagem , Levamisol/uso terapêutico , Contagem de Ovos de Parasitas , Ovinos , Vacinas/administração & dosagemRESUMO
The genetic diversity of a single nucleotide polymorphism (SNP) at the exon 20 (T945M) of the leptin receptor gene (LEPR) and of three short tandem repeats (STRs BM7225, BMS694, and BMS2145) linked to LEPR was investigated in three beef cattle herds (Brangus Ibagé, Charolais, and Aberdeen Angus). A cheap and effective new method to analyze the T945M polymorphism in cattle populations was developed and the possible role of these polymorphisms in reproduction and weight gain of postpartum cows was evaluated. High levels of genetic diversity were observed with the average heterozygosity of STRs ranging from 0.71 to 0.81. No significant association was detected between LEPR markers and reproductive parameters or daily weight gain. These negative results suggest that the LEPR gene polymorphisms, at least those herein described, do not influence postpartum cows production.
RESUMO
We used 550 Braford and 214 Brangus-Ibagé bulls to study the association between Y chromosome morphology and the evaluation of breeding-soundness, karyotyping and breeding records were used to assess Y chromosome morphology. In general, no direct association was detected between the individual type of Y chromosome and reproductive fitness as previously estimated through breeding soundness examination. The type of breeding strategy used to form the synthetic breeds was also analyzed. The Braford breed is about 3/8 Zebu (Bos taurus indicus) and 5/8 Hereford (Bos taurus taurus) but when the breeding strategy used 1/4 Zebu animals to produce Braford bulls which were 3/8 Zebu a greater percentage of the bulls had to be culled due to reproductive problems. Our study shows that certain interactions between genotypes can be detrimental to the reproductive efficiency of 3/8 Zebu animals and that breeding strategies avoiding or favoring certain genotypes can be used to reduce the percentage of bulls from synthetic breeds that are culled due to problems with semen quality.