Diagnóstico e monitoramento da doença respiratória em bezerras da raça holandês através de escores clínicos e exame ultrassonográfico e sua relação com os fatores de risco e índices de desempenho

Abstract

The objective was to evaluate the Wisconsin Score (WI Score), California Score (CA Score) and Pulmonary Ultrasonography in the diagnosis of respiratory disease in heifers and to establish the effect of this disease on the zootechnical performance of these animals and the risk factors involved. The study was carried out on an intensive commercial dairy farm, where 193 heifers were evaluated on diagnostic methods from study entry. Thus, 328 assessments were carried out between the 1st to 6th week of life (BI), 539 between the 8th to 12th week of life (BF), 887 from the 1st to 12th week of life (BG), 291 from the 16th to 24th week of life (RC) and 1158 from the 1st to 24th week of life (TA). Overall, 79.3% (153/193) of the calves had at least one positive exam on lung ultrasound, 65.2% (126/193) on the WI score, 60.1% (116/193) on the AC score and 74% (142/193) received at least one treatment for respiratory disease until the 12th week of life, when they were weaned. In the first week of life, only one heifer was positive on lung ultrasound and later the number of positive animals did not change over the weeks (p>0.05, mean of 41%). From the 4th to the 6th week of life, there was a greater proportion of positive cases in the ultrasound score >3, positive in the WI score and in the number of treatments for pneumonia. Throughout the study, the main presentation of the respiratory disease was subclinical pneumonia, positive cases on ultrasound and negative cases on the WI score, which intensified from the 8th week of life and this was responsible for the low agreement between the WI score and pulmonary ultrasound (kappa index, 9.1 to 21.9%) and its low diagnostic sensitivity throughout the study (20.2 to 39.2%). Ultrasonographic score 1, presence of diffuse comet tails, was observed in only four animals and these died a few days after diagnosis (1 to 5 days) due to septicemia caused by Salmonella Dublin. Regarding risk factors, there was a significant association between passive immunity transfer and the number of pulmonary consolidations >1cm on ultrasound (BG y=0.81-0.047, R2=0.004, P= 0.021; TA y=0.82-0.055 x, R2= 0.0061, P=0.003) and with the number of cases of treatment for pneumonia (y=2-0.13x, R2 0.021, P=0.044). The total number of days in diarrhea had a significant association with the number of cases treated for pneumonia (y=0.79+0.04x, R2=0.022, P=0.04). In positive ultrasound exams, in 72.7% (339/466) consolidations were present only in the right lung, 87.6% (410/466) were present in the cranial part of the cranial lobe and in 42.9% (201/466) 466) restricted to this pulmonary portion. In the performance evaluation, an association between lower weight gain and an increase in the number of intercostal spaces with lesions >1cm was observed (BI (y=0.63-0.044x, R2=0.05, P=0.002; BG y =0.85-0.038x, R2=0.027, P=0.011; RC y=0.86-0.055x, R2=0.02; P=0.02; TA y=0.86-0.04x, R2 =0.025, P=0.001) and for the number of positive cases in the WI score (BG y=0.84-0.15x, R2=0.02, P=0.015; TA y=0.84-0.14x, R2=0.016, P=0.004) A one-point increase in the mean value of intercostal spaces with consolidations > 1cm increased the death rate by 51% (Hazard ratio=1.51; 95% CI (1.16-1.97; P=0.002) and for an increase in WI score values, by 35% (Hazard ratio =1.35; 95% CI (1.12-1.63; P=0.002), up to 19 months of life. , a high prevalence of respiratory disease was observed, mainly due to subclinical pneumonia, diagnosed by the use of pulmonary ultrasound. must be evaluated. The presence of respiratory disease was associated with worse transfer of passive immunity, days in diarrhea, less weight gain, and a greater chance of death. Despite being significant, the strength of these associations was low, which shows the multifactorial character of respiratory disease and that other factors should be studied.