RESUMO
Se evaluó el efecto de cinco desinfectantes comerciales suministrados en el agua de bebida, sobre el estado de salud y desempeño productivo de pollos de engorde. Se utilizaron 216 pollitos machos Arbor Acres de un día de nacidos, durante 28 d y distribuidos en seis tratamientos: A: agua sin desinfectante; B:250 ppm de un fenol; C:250 ppm de un aldehído; D:250 ppm de un halógeno; E:250 ppm de ácidos orgánicos y F:250 ppm de un cresol. Cada tratamiento contó con seis réplicas de seis aves cada una. Se evaluaron variables productivas: consumo de alimento y agua, mortalidad y peso. Al final del ensayo, se tomaron muestras de órganos para histopatología y de sangre periférica para hematología y determinación de SGPT y TPP. No hubo diferencias estadísticas para el incremento de peso, el consumo de alimento y la conversión de alimento entre los tratamientos. El consumo de agua fue mayor en el tratamiento C (3.114,57 mL) (p<0,05). No se observó mortalidad en ninguno de los tratamientos. Histopatológicamente, no hubo alteración evidente en duodeno. Se observó leve congestión de los vasos portales y sinusoides hepáticos en todos los tratamientos, excepto en el tratamiento A. También se observó congestión moderada de vasos intersticiales e infiltrado mononuclear en el riñón, para los tratamientos B, E y F; observándose riñones normales en los pollos de los los tratamientos A, C y D. Los niveles séricos de glutamato-piruvato-transaminasa (GPT) y las proteínas plasmáticas fueron similares entre los tratamientos. Se observó leucopenia (p<0,05) en los tratamientos C (4.933 cel/mL), D (2.466 cel/mL), E (3.466 cel/ mL) y F (3.400 cel/ mL), con respecto a los tratamientos A (9.600 cel/ mL) y B (7.266 cel/ mL). El hematocrito fue menor al control (tratamiento A) en todos los tratamientos (p<0,05). A pesar de no observarse lesiones evidentes en duodeno, el consumo de desinfectantes produjo anemia y leucopenia, así como también lesiones moderadas en hígado ...
The effect of the addition of five commercial disinfectants to the drinking water on health status and on productive performance of broilers was evaluated. Two-hundred and sixteen one-day old male Arbor Acres broilers were allocated into six treatments for 28 days, as follows: A: water without disinfectant; B:250 ppm of a phenol; C:250 ppm of an aldehyde; D:250 ppm of an halogene; E:250 ppm of organic acids; and F: 250 ppm of a cresol. Each treatment included six replicates of six broilers. Productive variables such as feed and water intake, body weight, feed conversion, and mortality, were assessed. At the end of the experiment, tissue samples were taken for histopathology studies; peripheral blood was withdrawn for hematocrit (Ht) and white cells count; and for measuring serum glutamic-pyruvic transaminase (SGPT) and total plasma proteins (TPP). The results showed no statistical differences (p>0.05) among treatments for body weight gain, feed intake, and feed conversion. Water intake was highest (p<0.05) in treatment C (3,114.57 mL). No mortality was seen in all treatments. No evident histopathology changes were observed in duodenum samples. A minor congestion of portal blood vessels, and sinusoids was evidenced in all treatments, except for treatment A. Additionally, a moderate congestion along with a mononuclear infiltrate of interstitial blood vessels was evident in kidneys of treatments B, E, and F, whereas treatments A, C, and D had a normal appearance. The SGPT and TPP levels were similar (p>0,05) among treatments. There was leukopenia (p<0.05) in treatments C (4,933 cells/mL), D (2,466 cells/mL), E (3,466 cells/mL), and F (3,400 cells/ mL), compared to treatments A (9,600 cells/ mL) and B (7,266 cells/ mL). The Ht was lower (p<0.05) than the control in all treatments. Despite the absence of overt duodenal lesions, consumption of disinfectants in the drinking water caused anemia and leucopenia in all treatments, as well as moderate ...
RESUMO
Here we report the biological and molecular characterization of a virulent genotype VII Newcastle disease virus (NDV) circulating in Venezuela and the assessment of the vaccination efficacy under field conditions compared to controlled rearing conditions. Biological pathotyping showed a mean embryo dead time of 50 h and an intracerebral pathogenicity index of 1.86. Sequence-based phylogenetic analysis demonstrated that the virus belongs to genotype VII in class II (a genotype often found in Asia and Africa), representing the first report of the presence of this genotype in the continent of South America. A vaccine-challenge trial in commercial broilers reared in fields or in a experimental setting included dual (live/killed) priming of 1-day-old chicks plus two live NDV and infectious bursal disease virus (IBDV) field vaccinations at days 7 and 17, followed by a very stringent genotype VII NDV challenge at day 28. Serology for NDV and IBDV, bursal integrity, and protection against NDV lethal challenge were assessed. At 28 days, field vaccinates showed significantly lower NDV (1,356 versus 2,384) and higher IBD (7,295 versus 1,489) enzyme-linked immunosorbent assay (ELISA) antibody titers than the experimentally reared birds. A lower bursal size and bursa-body weight ratio (P < 0.05) and higher bursa lesion score were also detected in the field set. Only 57.1% of field vaccinates survived the lethal challenge, differing (P < 0.05) from 90.5% survival in the experimental farm. Overall, results confirmed the presence of the genotype VII viruses in South America and suggest that field-associated factors such as immunosuppression compromise the efficacy of the vaccination protocols implemented.
