RESUMEN
Our aim was to investigate the associations between management factors, compliance with current legislation, and herd-level calf mortality. In a national calf welfare audit, veterinary inspectors from the Norwegian Food Safety Authority assessed compliance with current legislation on calf welfare (n = 912 herds). Nine criteria were assessed and rated as satisfactory (1) or not satisfactory (0): housing, natural behavior, single pens, colostrum feeding, feeding, water, surveillance, illness/injuries, and <5% mortality rate. In addition, a short questionnaire on milk feeding management for 3-wk-old calves was distributed to all national calf welfare audit herds, and data on mortality and disease recordings were obtained from the Norwegian Dairy Herd Recording System (NDHRS). A herd welfare compliance score (WCS) for each farm was constructed, summarizing the results for the individual criteria. Most herds had a high WCS (median 9.0, range 2-9). Fifty-six percent of the national calf welfare audit herds (508/912) responded to the questionnaire. We performed a cross-sectional study using a data set from 431 herds with available data on recorded disease and mortality events from the NDHRS, recordings from the national calf welfare audit, and the questionnaire. A mixed-effects negative binomial model with Norwegian Food Safety Authority district as the random effect was fitted to the data. Of the 416 herds with available data on calf mortality, 108 (25.9%) reported no mortality in 2016, and the median 6-mo mortality rate was 0.064 (interquartile range 0-0.11) dead calves per 6 calf-months at risk, based on NDHRS recordings. Calf mortality rates were higher in herds whose calves did not have free access to water (incidence rate ratio 1.29; 95% confidence interval 1.02-1.64) and higher in herds that had reported calf disease events (incidence rate ratio 1.31; 95% confidence interval 1.09-1.54). Neither the WCS nor any of the calf milk feeding management factors were associated with mortality, but more than half of producers (59.6%) fed less milk than currently recommended for 3-wk-old calves (8 L/d first 3 to 4 wk). These results indicate that a lack of access to water was associated with higher calf mortality rates. Herds with registered calf disease events had a higher incidence rate ratio of mortality. This finding may be linked to suboptimal calf management, leading to more calf diseases and mortality; or it may be that veterinary consultancy occurs too late or only for the worst cases. There is room for improvement in Norwegian dairy calf management, and water should be provided to young calves.
Asunto(s)
Bienestar del Animal/legislación & jurisprudencia , Animales Recién Nacidos/fisiología , Enfermedades de los Bovinos/mortalidad , Industria Lechera/legislación & jurisprudencia , Dieta/veterinaria , Leche , Animales , Bovinos , Estudios Transversales , Industria Lechera/métodos , Granjas , Femenino , Masculino , Noruega , EmbarazoRESUMEN
At birth, calves are functionally monogastric and remain so for the first weeks of life. Milk in the rumen may cause indigestion, diarrhea, and reduced growth. Calves are often fed cold milk from a large-aperture teat, but warm milk and sucking behavior are believed to trigger the esophageal reflex. The aim of this study was to use radiography to estimate the lowest milk temperature that can be given to dairy calves at high and low intake rates without causing milk in the rumen. Our hypothesis was that cold milk drunk at high speed would cause insufficient closure of the esophageal groove and hence milk in the rumen. Fifteen Norwegian Red calves, 9 to 27 d of age, weighing between 45.5 and 71.0 kg, were tested according to the response surface pathway design. Each calf was offered 4 L of milk from both a small- (2 mm) and a large-aperture (19 mm) teat. The milk contained barium sulfate, and radiography was applied before, during, and after the milk meal. Following radiography, the calves were returned to a group pen and observed for 2 h using continuous live behavioral observation to detect signs of abdominal pain or discomfort. Starting with a low number of subjects and increasing this number with increasing design levels reduces the sample size without reducing the statistical power. The minimum milk temperature was estimated to be 8°C. No behavioral signs of pain or discomfort were observed, but shivering was noted in several calves drinking 8°C milk. These results strengthen the argument that calves can be fed large milk meals without risk of causing milk in the rumen, even cold milk drunk at high speed.