RESUMEN
Assessment of lameness prevalence and severity requires visual evaluation of thelocomotion of a cow. Welfare schemes including locomotion assessments are increasingly being adopted, and more farmers and their veterinarians might implement a locomotion-scoring routine together. However, high within-observer agreement is a prerequisite for obtaining valid mobility scorings, and within-observer agreement cannot be estimated in a barn, because the gait of cows is dynamic and may change between 2 occasions. The objective of this study was to estimate the within-observer agreement according to the observers' educational background and experience with cattle, based on video recordings with very diverse types of gait. Groups of farmers, bovine veterinarians, first- and fourth-year veterinary students, researchers, and cattle-inexperienced sensory assessors evaluated mobility using a 5-point mobility score system developed specifically for walking cows (n=102 observers). The evaluation sessions were similar for all groups, lasted 75 min, and were organized as follows: introduction, test A, short training session, break, and test B. In total, video recordings of 22 cows were displayed twice in a random order (11 cows in each test × 2 replicates). Data were analyzed applying kappa coefficient, logistic regression, and testing for random effects of observers. The crude estimates of 95% confidence interval for weighted kappa in test A and B ranged, respectively, from 0.76 to 0.80 and 0.70 to 0.75. When adjusting for the fixed effects of video sample and gait scoring preferences, the probability of assigning the same mobility score twice to the same cow varied from 55% (sensory assessors) to 72% (fourth-year veterinary students). The random effect of the individual observers was negligible. That is, in general observers could categorize the mobility characteristics of cows quite well. Observers who preferred to assess the attributes back arch or the overall mobility score (based on uneven gait) had the highest agreement, respectively, 69 or 68%. The training session seemed insufficient to improve agreement. Nonetheless, even novice observers were able to achieve perfect agreement up to 60% of the 22 scorings with merely the experience obtained during the study (introduction and training session). The relatively small differences between groups, together with a high agreement, demonstrate that the new system is easy to follow compared with previously described scoring systems. The mobility score achieves sufficiently high within-observer repeatability to allow between-observer agreement estimates, which are reliable compared with other more-complex scoring systems. Consequently, the new scoring scale seems feasible for on-farm applications as a tool to monitor mobility within and between cows, for communication between farmers and veterinarians with diverse educational background, and for lamenessbenchmarking of herds.
Asunto(s)
Enfermedades de los Bovinos/diagnóstico , Enfermedades de los Bovinos/epidemiología , Cojera Animal/diagnóstico , Variaciones Dependientes del Observador , Grabación en Video , Adulto , Animales , Bovinos , Femenino , Marcha , Humanos , Modelos Logísticos , Masculino , Prevalencia , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Evaluating the effects of all interventions in a dairy herd, including the effects of various herd health management programs (HHMP), is highly relevant. A traditional randomized controlled trial is the gold standard but is likely practically impossible or prohibitively expensive to use for a general evaluation of a HHMP. Generalizability may also be poor because of the dynamics of the production contexts. In this study, we demonstrate an approach for evaluating the effects of an HHMP in the field, specifying an intervention theory for an ongoing HHMP in the context of the Danish dairy industry. As an example, we suggest one coherent analytical approach for studying the possible effects on milk production of systematic postpartum examinations of vaginal discharge, which is supposed to improve detection and treatment of metritis or endometritis. This routine is one component of the HHMP. The data consisted of 121 herds and 76,953 lactations over a 15-yr period. For parity group 1, the negative effects of metritis (despite treatment) on 305-d milk production after a normal calving were reduced by 116 kg of energy-corrected milk after enrollment in the HHMP. For parity group 2 and parity group >2, enrollment in the HHMP resulted in a 129-kg and an 80-kg energy-corrected milk yield increase in milk production, respectively. The results indicate that effects of the HHMP existed, which were mediated through improved metritis detection. This study demonstrates the importance of a clear-cut intervention theory, although even with a theory, the research question can be too herd and context specific. In such a case, a within-herd randomized controlled trial study design seems to be the only way to achieve a valid result for a given herd, and acquiring valid results from an observational multi-herd study will be very difficult.
Asunto(s)
Crianza de Animales Domésticos/métodos , Enfermedades de los Bovinos/prevención & control , Endometritis/veterinaria , Animales , Bovinos , Industria Lechera , Endometritis/prevención & control , Femenino , Lactancia , Paridad , EmbarazoRESUMEN
Lameness causes decreased animal welfare and leads to higher production costs. This study explored data from an automatic milking system (AMS) to model on-farm gait scoring from a commercial farm. A total of 88 cows were gait scored once per week, for 2 5-wk periods. Eighty variables retrieved from AMS were summarized week-wise and used to predict 2 defined classes: nonlame and clinically lame cows. Variables were represented with 2 transformations of the week summarized variables, using 2-wk data blocks before gait scoring, totaling 320 variables (2 × 2 × 80). The reference gait scoring error was estimated in the first week of the study and was, on average, 15%. Two partial least squares discriminant analysis models were fitted to parity 1 and parity 2 groups, respectively, to assign the lameness class according to the predicted probability of being lame (score 3 or 4/4) or not lame (score 1/4). Both models achieved sensitivity and specificity values around 80%, both in calibration and cross-validation. At the optimum values in the receiver operating characteristic curve, the false-positive rate was 28% in the parity 1 model, whereas in the parity 2 model it was about half (16%), which makes it more suitable for practical application; the model error rates were, 23 and 19%, respectively. Based on data registered automatically from one AMS farm, we were able to discriminate nonlame and lame cows, where partial least squares discriminant analysis achieved similar performance to the reference method.
Asunto(s)
Conducta Animal/fisiología , Enfermedades de los Bovinos/diagnóstico , Lactancia/fisiología , Cojera Animal/diagnóstico , Animales , Automatización , Bovinos , Enfermedades de los Bovinos/fisiopatología , Industria Lechera , Análisis Discriminante , Femenino , Marcha , Cojera Animal/fisiopatología , Análisis de los Mínimos Cuadrados , Leche/metabolismo , Monitoreo Fisiológico/veterinaria , Paridad , Embarazo , Sensibilidad y EspecificidadRESUMEN
In this study, 3 commonly used tests to diagnose ketosis were evaluated with a latent class model to avoid the assumption of an available perfect test. The 3 tests were the KetoLac BHB (Sanwa Kagaku Kenkyusho Co. Ltd., Nagoya, Japan) test strip that tests milk for ß-hydroxybutyrate, the KetoStix (Bayer Diagnostics Europe Ltd., Dublin, Ireland) test strip that tests urine for acetoacetate, and the fat-to-protein percentage ratio (FPR) in milk. A total of 8,902 cows were included in the analysis. The cows were considered to be a random sample from the population of Danish dairy cattle under intensive management, thus representing a natural spectrum of ketosis as a disease. All cows had a recorded FPR between 7 and 21 d postpartum. The KetoLac BHB recordings were available from 2,257 cows and 6,645 cows had a KetoStix recording. The recordings were analyzed with a modified Hui-Walter model, in a Bayesian framework. The specificity of the KetoLac BHB test and the KetoStix test were both high [0.99 (0.97-0.99)], whereas the specificity of FPR was somewhat lower [0.79 (0.77-0.81)]. The best sensitivity was for the KetoStix test [0.78 (0.55-0.98)], followed by the FPR [0.63 (0.58-0.71)] and KetoLac BHB test [0.58 (0.35-0.93)].
Asunto(s)
Acetoacetatos/orina , Enfermedades de los Bovinos/diagnóstico , Cetosis/veterinaria , Leche/química , Juego de Reactivos para Diagnóstico/veterinaria , Ácido 3-Hidroxibutírico/análisis , Animales , Bovinos , Enfermedades de los Bovinos/orina , Grasas de la Dieta/análisis , Femenino , Cetosis/diagnóstico , Cetosis/orina , Proteínas de la Leche/análisis , Sensibilidad y EspecificidadRESUMEN
Infection with Mycobacterium avium ssp. paratuberculosis (MAP) in dairy cattle often results in reduced milk production and premature culling. Some test-positive animals can live for years without being affected by infection, whereas others are test negative when they die from the infection. Our objective was to describe the deviation in milk production of cows with various MAP antibody profiles compared with their repeatedly test-negative herdmates in the same parity. Data were obtained from herds participating in the Danish control program on paratuberculosis, for which 4 annual MAP antibody ELISA of individual cows were performed per herd per year. A total of 136,489 ELISA results from 38,998 dairy cows in 64 herds were used along with 484,285 test-day records on energy-corrected milk (ECM) yield. Cows were divided into 6 antibody groups based on their repeated milk ELISA results: A0) repeated ELISA negative; A1) ELISA negative, but only once; A2) ELISA negative on the last 3 tests, but with 1 previous positive result; A3) ELISA negative on the last test, but with 1 or more previous positive results; A4) last sample was ELISA positive, but all previous were negative; and A5) at least the last 2 samples were ELISA positive. The expected test-day kilograms of ECM by herd and parity were estimated for cows in antibody group A0. Deviations from expected milk production were then assessed for cows in the other antibody groups relative to the time of the first test-positive ELISA result (D 0). Cows in groups A2, A3, and A5 produced approximately 0.5 kg of ECM/d more than cows in group A0 at 300 d before D 0. Cows in group A4 had a decline in milk production from d 300 before D 0, with daily milk production reduced by 5 kg of ECM at 200 d after D 0. Milk production of cows in group A5 was reduced by 2.5 kg of ECM at 300 d after D 0 compared with 300 d before D 0, whereas cows in groups A2 and A3 produced 0.5 kg of ECM more than cows in group A0. The conclusions of the study were that 1) increasing the number ELISA tests increases the predictive value of ELISA for inference on milk production losses, 2) a combination of ELISA with assessment of observed milk production may be a valuable tool for decisions on culling, and 3) the declines in milk production attributable to MAP occurred over a long time period, and may not be realized by the herd manager without more advanced management tools such as the model proposed here.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Enfermedades de los Bovinos/inmunología , Lactancia/inmunología , Leche/metabolismo , Paratuberculosis/inmunología , Animales , Bovinos , Femenino , Factores de TiempoRESUMEN
The disease risk is very high among transition cows that may suffer from poor appetite. The aim of the present study was therefore to investigate the effect of drenching on energy balance, hydration state and selected production parameters in fresh cows. Twenty-one Danish Holstein-Friesian dairy cows in late pregnancy were randomly allocated to either treatment (TG) or control group (CG). TG cows were drenched twice with 20 l of water containing a mixture of calcium propionate, MgSO(4), and KCL specifically developed for prophylactic treatment of fresh cows. The results indicated that cows become dehydrated around calving, losing on average 53 l (TG) and 24.5 l (CG) of extra-cellular fluid, respectively. The drenching volume applied in the present study did not affect the degree of hydration after calving. Based on blood NEFA and BHB values it was shown that drenching caused a reduction in the degree of negative energy balance (NEB). Somatic cell count (SCC) for cows in first lactation was lower in the TG compared to CG. Milk yield was unaffected by treatment. We conclude that prophylactic drenching added little to the health promotion in the transition cows in the present study. Instead, increased focus on management routines would probably be of more value.
Asunto(s)
Bovinos/fisiología , Metabolismo Energético/fisiología , Periodo Posparto/fisiología , Agua/administración & dosificación , Ácido 3-Hidroxibutírico/sangre , Animales , Temperatura Corporal/fisiología , Deshidratación/metabolismo , Deshidratación/terapia , Ácidos Grasos no Esterificados/sangre , Femenino , Hematócrito/veterinaria , Lactancia , Sulfato de Magnesio/administración & dosificación , Leche/química , Leche/citología , Leche/metabolismo , Cloruro de Potasio/administración & dosificación , Embarazo , Propionatos/administración & dosificación , Distribución Aleatoria , Análisis de RegresiónRESUMEN
Lameness causes major financial losses and welfare problems in dairy herds. Prevention of foot lesions may suffice in the majority of lameness cases. The objectives of this longitudinal study were to describe the dynamics and associations between abnormal hind leg conformation, asymmetric claws, lameness, and foot lesions in 122 Danish Holstein heifers from an average of 41 d before first calving until dry off or culling. The cattle were housed either in a free-stall system with cubicles or in deep-bedded straw yard. The claws of all cattle were examined on up to 5 occasions. The associations between foot lesions, lameness, symmetry of the claws, shape of the dorsal toe-wall, and the conformation of the hind legs were examined statistically using mixed models. A large proportion (81%) of the heifers had cow-hocked conformation, with wide-based stance, hocks together, and lateral rotation of the foot before calving, and 25% of the heifers had locomotion scores above 2, indicating signs of lameness, before calving. Our results indicate that lameness, abnormal conformation, and lesions acquired precalving persist throughout the first lactation. Thinner cows were more cow-hocked, and cow-hocked cows had a higher frequency of sole hemorrhages. Increased severity of white line lesion was associated with greater claw asymmetry. More severe lameness and sole hemorrhages were found in symmetric claws.
Asunto(s)
Enfermedades de los Bovinos/etiología , Miembro Posterior/anomalías , Cojera Animal/etiología , Animales , Bovinos , Dinamarca , Femenino , Enfermedades del Pie/etiología , Enfermedades del Pie/veterinaria , Pezuñas y Garras/anomalías , Modelos Lineales , Estudios Longitudinales , Estudios Prospectivos , Reproducibilidad de los ResultadosRESUMEN
Monte Carlo simulation was used to predict the long-term financial performance related to the technical performance of dairy herds. The indicators addressed were derived from data collected routinely in the herd. They indicated technical performance that can be affected by the farmer or the consultant, and they were derived from expected cause-effect relations between technical performance and financial performance at the herd level. The study included the indicators shape of lactation curve, reproduction efficiency, heifer management, variation between cows in lactation curve persistency, mortality in cows and calves, dynamics of body condition, and somatic cell counts. Each indicator was defined by 2 or 3 levels, and 2- and 3-factor interactions were included in the simulation experiment, which included 72 scenarios. Each scenario was replicated 200 times, and the resulting gross margin per cow was analyzed as the measure of financial performance. The potential effects of the selected indicators on the gross margin were estimated by means of an ANOVA. The final model allowed estimation of the financial value of specific changes within the key performance indicators. This study indicated that improving the shape of the herd-level lactation curve by 1 quartile was associated with an increase in gross margin of euro 227 per cow year. This represents 53% of the additional available gross margin associated with all the management changes included in the study. The improved herd-level lactation curve increased the gross margin 2.6 times more than improved reproduction efficiency, which again increased the gross margin 2.6 to 5.9 times more than improved management related to heifers, body condition score, mortality, and somatic cell counts. These results were implemented in a simple "metamodel" that used data extracted from ordinary management software to predict herd-specific financial performance related to major management changes. The metamodel was derived from systematic experiments with a complex simulation model that was used directly for advanced herd-specific decision support. We demonstrated the use of these key performance indicators to forecast the financial consequences of different "what-if" herd management options, with emphasis on herd health economics.
Asunto(s)
Bovinos , Industria Lechera/economía , Leche/economía , Modelos Económicos , Animales , Simulación por Computador , Dinamarca , Femenino , Método de Montecarlo , ReproducciónRESUMEN
In a cross-sectional study of 6240 Danish Holstein cows in 55 herds using loose-housing systems, sole haemorrhages and heel horn erosions occurred frequently in almost all the herds. Digital dermatitis occurred in 47 of the 55 herds (85 per cent). Spearman correlation coefficients revealed relationships between lameness and sole ulcer (0.36), between heel horn erosion and sole haemorrhage (0.39), between heel horn erosion and interdigital dermatitis (0.29) and between sole ulcer and double sole (0.26). The prevalence of heel horn erosion, sole haemorrhage, interdigital dermatitis and digital dermatitis appeared to be most affected by herd-level factors. The associations between individual foot trimmers and all the foot lesions were statistically significant. The risk of interdigital dermatitis increased with decreasing amounts of bedding. Cows housed throughout the year had a marginally higher risk of sole haemorrhage.
Asunto(s)
Enfermedades de los Bovinos/patología , Enfermedades del Pie/veterinaria , Crianza de Animales Domésticos , Animales , Bovinos , Enfermedades de los Bovinos/epidemiología , Estudios Transversales , Dinamarca/epidemiología , Femenino , Enfermedades del Pie/epidemiología , Enfermedades del Pie/patología , Vivienda para Animales , PrevalenciaRESUMEN
Body condition scores (BCS) are very useful for dairy herd management and breeding programs, but the consistency and quality of recordings made by consultants in the field are unknown. The objectives of this study were 1) to estimate the agreement in BCS within and among practicing dairy veterinarians and 2) to provide an indication of the effects of training and the value of calibration, and of what efforts need to be made to obtain a validity and precision in BCS adequate for management purposes. A total of 2,230 scores were recorded by 51 practicing dairy veterinarians and 6 highly trained instructors. The 6 instructors were cross-trained to validate calibration consistency in assigning BCS. Each individual scored approximately 20 cows twice, with the second scoring occurring approximately 2.5 h after the first. Between the 2 recordings, the respective instructors conducted a training session for the practicing veterinarians using other cows. A weighted kappa coefficient was used to assess agreement among and within classifiers. Excellent agreement (kappa > or = 0.86) was documented between repeated BCS recorded for the same cows by the highly trained instructors. In addition, the BCS provided by multiple classifiers from the instructor team appeared to be comparable across herds and classifiers. This legitimizes the use of BCS for benchmarking at both the cow and the herd level. The within-classifier and between-classifier kappa values were in the ranges of 0.22 to 0.75 and 0.17 to 0.78, respectively, in the group of practicing dairy veterinarians. Many of the veterinarians provided estimates of average BCS that differed considerably from the BCS recorded by the instructors. Between-classifier comparisons of herd BCS are not warranted unless a validation has been performed. If scores are collected by multiple classifiers with varying experience, a valid but imprecise estimate of the true population mean of BCS may be obtained if classifiers are inexperienced. The limited training effort used in this study seemed to have brought about substantial improvement in the validity and precision of the BCS determined by practicing veterinarians, compared with the BCS recorded on the same cows by highly trained classifiers.
Asunto(s)
Bovinos/fisiología , Industria Lechera/métodos , Estado de Salud , Variaciones Dependientes del Observador , Animales , Constitución Corporal , Dinamarca , Femenino , Humanos , Reproducibilidad de los ResultadosRESUMEN
The aim of the present study was to examine the diversity of Staphylococcus aureus isolates from bovine intramammary infections (IMI) in nine dairy herds, and compare these with isolates from other sites on the cows by phage- and ribotyping. Whether colonisation of milkers with S. aureus could be a source of infection for bovine IMI was investigated. In addition, 100 epidemiologically unrelated S. aureus isolates from asymptomatic human carriers were also phage- and ribotyped to compare the human and bovine reservoir of S. aureus in Denmark. A total of 625 S. aureus isolates from bovine IMI, bovine skin lesions, milking personnel, and non-farm-related human carriers were included in the study. Certain types predominated in one or several herds during the study period of one-and-a-half to two years, whereas the presence of other types was of a more sporadic nature. Within the individual herds, there was a close correspondence between ribo- and phage types of S. aureus isolated from bovine intramammary infections and skin lesions. Isolates from milking personnel, however, were not identical to any of the predominant intramammary strains. Furthermore, several of the isolates from milking personnel showed ribo- and phage patterns identical to S. aureus isolates from human carriers. The findings of the present study underline the importance of strict milking hygiene and improvement of current mastitis therapy. The results support the hypothesis that some S. aureus mastitis strains are more contagious, virulent or persistent than others. The human reservoir of S. aureus does not play a major role as a source of bovine intramammary infections.
Asunto(s)
Mastitis Bovina/microbiología , Infecciones Estafilocócicas/veterinaria , Staphylococcus aureus/aislamiento & purificación , Enfermedades de los Trabajadores Agrícolas/microbiología , Animales , Portador Sano/microbiología , Bovinos , Industria Lechera , Dinamarca , Reservorios de Enfermedades , Femenino , Humanos , Infecciones Estafilocócicas/microbiologíaRESUMEN
This study examined the possibilities of using clinical parameters related to the bovine udder for characterisation of udder health. Five clinicians performed systematic clinical recordings of udder health at 3 visits to 4 dairy herds. Several of the clinical parameters were scored on an ordinal scale. The agreement between clinicians was compared using kappa statistics. Factor analysis was used to identify udder types. The clinical evaluations showed substantial variation among clinicians. Parameters that were not directly related to pathological conditions showed the highest variation e.g. length of the claws, teat shape and hardness of the udder parenchyma. On the other hand, evaluation of pathological parameters such as nodes in the udder, skin lesions and oedema showed good agreement between clinicians. Udder types identified by means of factor analysis were found to be suitable for characterisation of udder health. Especially one factor related to dry quarters and udder asymmetry showed a more consistent relationship to milk yield than traditionally applied udder health parameters such as treatment rate and cell count. It is concluded that there is a considerable need for increased efforts among clinicians in order to standardise clinical recordings. It is further concluded that certain combinations of extended clinical recordings have significant perspectives for future characterisation of udder health.
Asunto(s)
Industria Lechera , Glándulas Mamarias Animales/patología , Animales , Bovinos , Dinamarca , Análisis Factorial , Femenino , Estado de SaludRESUMEN
An epidemiological study was conducted in 18 dairy herds with the objective to characterize those groups of cows where skin injuries to the body and thighs occurred most frequently. Data were analyzed with multivariable logistic regression. The epidemiologic patterns were different in first and later lactations. In first lactation some degree of injury occurred among 7.7% of 1793 cows. For most cows occurrence of sole ulcer was positively associated with injury while occurrence of heel horn erosion was negatively associated with injury. The association between injury and body weight differed depending on month of calving (significant interaction). Injuries occurred most frequently among high yielding cows. Severe reproductive, metabolic, and/or infectious diseases were associated with injuries. In later lactations some degree of injury occurred among 13.4% of 832 cows in lactations 2 to 9 where severity of injury increased with lactation number. Injuries occurred least frequently at examinations made in the January to March. They occurred most frequently among cows with sole ulcers. Calving in March through October was associated with injuries especially if the cows were treated for limb disorders. Most cases of injuries occurred early or late in lactation or among high or very low yielding cows in lactations 2 to 9.
Asunto(s)
Enfermedades de los Bovinos/epidemiología , Bovinos/lesiones , Pezuñas y Garras/patología , Piel/lesiones , Animales , Femenino , Enfermedades del Pie/epidemiología , Enfermedades del Pie/veterinaria , Factores de Riesgo , Suecia/epidemiologíaRESUMEN
Based on 2 previous surveys on the occurrence of infection with bovine virus diarrhoea virus (BVDV) in Danish and Michigan dairy herds, the prevalence and incidence of the infection were compared. The presence of certain possible risk factors for the occurrence of infection in the 2 areas were summarized and it was investigated if any of these risk factors had significant effect on the presence of animals persistently infected (PI) with BVDV in the dairy herds. Information on the cattle population density in the 2 areas was obtained from statistical yearbooks. Further information for the individual farms on age distribution, housing of animals, herd size, pasturing and purchasing policy was gathered. The prevalence of PI animals was more than 10 times higher in Denmark as compared to Michigan. In herds without PI animals, the annual incidence of seroconversion as calculated from the age specific prevalence of antibody carriers varied in most age groups between 20-25% in Denmark and between 5-10% in Michigan. All investigated risk factors except for herd size were in favour of a lower prevalence of infection in Michigan. The use of having animals on pasture and at the same time having purchased more than 40 animals within recent 3 1/2-4 years were significantly associated with presence of PI animals in the dairy herds (p = 0.01) when tested by the Mantel-Haenszel chi 2. Using multivariable logistic regression, the occurrence of PI animals was found to be significantly related to the study area (Michigan and Denmark) as well as to herd size and purchase intensity.
Asunto(s)
Diarrea Mucosa Bovina Viral/epidemiología , Animales , Bovinos , Industria Lechera , Dinamarca/epidemiología , Femenino , Incidencia , Michigan/epidemiología , Prevalencia , Factores de RiesgoRESUMEN
A cross-sectional observational study with repeated observations was conducted on 16 Danish dairy farms to quantify the influence of observer, parity, time (stage in lactation) and farm on variables routinely selected for inclusion in clinical protocols, thereby to enable a more valid comparison of udder health between different herds. During 12 months, participating herds were visited 5 times by project technicians, who examined 20 cows and scored the selected clinical variables. The estimates of effect on variables were derived from a random regression model procedure. Statistical analyses revealed that, although estimates for occurrence of several the variables, e.g. degree of oedema, varied significantly between observers, the effects on many of these estimates were similar in size. Almost all estimates for occurrences of variables were significantly affected either parity and lactation stage, or by both e.g. udder tissue consistency. Some variables, e.g. mange, had high estimates for the farm component, and others e.g. teat skin quality had a high individual component. Several of the variables, e.g. wounds on warts, had a high residual component indicating that a there still was a major part of the variation in data, which was unexplained. It was concluded that most of the variables were relevant for implementation in herd health management, but that adjustments need to be made to improve reliability.
Asunto(s)
Indicadores de Salud , Glándulas Mamarias Animales/fisiología , Variaciones Dependientes del Observador , Animales , Bovinos , Estudios Transversales , Industria Lechera , Femenino , Humanos , Lactancia/fisiología , Paridad/fisiología , EmbarazoRESUMEN
Milk leakage in dairy cows is a symptom of impaired teat sphincter function. Milk leakage is related to an increased risk of mastitis in heifers and cows, and causes hygiene problems. The aim of our study was to assess whether teat shape, condition of teat orifice, and peak milk flow rate are risk factors for milk leakage. We conducted a longitudinal observational study in 15 German dairy farms in which cows were maintained in loose housing. The farms were visited monthly at 2 consecutive milkings. During the evening milking, milk flow curves were measured with the LactoCorder. Milk leakage was recorded during the subsequent morning milking, when cows entered the milking parlor. Immediately after detachment of the milking cluster, teat shape, teat end shape, and condition of the teat orifice of cows were assessed between 9 and 100 d in milk (DIM) and during late lactation (>250 DIM). Data from 1600 cows were analyzed. Milk leakage was treated as the binary response variable in a logistic regression model with herd as a random effect. Primiparous cows with high peak milk flow and teat canal protrusion were at greater risk of milk leakage. High peak milk flow rate, short teats, teat canal protrusion, inverted teat ends, and early lactation increased the risk of milk leakage in multiparous cows. Random herd effects accounted for only 10% of the total variation, indicating that the impact of management or other herd-level factors on the occurrence of milk leakage is virtually negligible for practical purposes.
Asunto(s)
Enfermedades de los Bovinos/etiología , Lactancia , Glándulas Mamarias Animales , Animales , Bovinos , Enfermedades de los Bovinos/patología , Enfermedades de los Bovinos/fisiopatología , Femenino , Alemania , Modelos Logísticos , Estudios Longitudinales , Glándulas Mamarias Animales/patología , Glándulas Mamarias Animales/fisiopatología , Mastitis Bovina/etiología , Factores de RiesgoRESUMEN
The objective of this study was to evaluate the use of hip height and width, body condition score, and relevant demographic information to predict body weight (BW) of dairy cows. Seven regression models were developed from data from 972 observations of 554 cows. Parity, hip height, hip width, and body condition score were consistently associated with BW. The coefficients of multiple determination varied from 80 to 89%. The number of significant terms and the parameter estimates of the models differed markedly among groups of cows. Apparently, these differences were due to breed and feeding regimen. Results from this study indicate that a reliable model for estimating BW of very different dairy cows maintained in a wide range of environments can be developed using body condition score, demographic information, and measurements of hip height and hip width. However, for management purposes, substantial improvements can be obtained by developing models that are specific to a given site.
Asunto(s)
Constitución Corporal , Peso Corporal , Bovinos/fisiología , Animales , Femenino , Modelos BiológicosRESUMEN
Danish organic dairy production is characterized by a low input of antibiotics for udder treatment and a high input of other mastitis control procedures. A study was conducted in 14 organic dairy herds with the objectives of obtaining a comprehensive description of clinical mastitis cases and identifying characteristic patterns in these results. Clinical signs, inflammatory reactions and microbiological identifications were obtained from 367 cases of clinical mastitis occurring over 18 months. Cow characteristics and preincident values such as milk yield and somatic cell count were obtained for each cow. Signs of previous udder inflammation were present in two-thirds of the clinical mastitis cases. Severe local inflammatory reactions were found in 21% of the cases and some indication of generalized signs such as fever and reduced appetite were found in 35% of the cases. Logistic regression analyses were performed based on the results of an initial (exploratory) multiple correspondence analysis. Coliform mastitis (6% of the cases) was rarely preceded by pathogen isolation or inflammatory reactions in the same quarter. Coliform mastitis cases usually occurred in one quarter only. Escherichia coli infections were typically (truly) acute cases. Bacteriologically negative mastitis (20% of the cases) showed strong similarities with clinical coliform mastitis. Staphylococcus aureus cases (18% of the cases) occurred most frequently in late lactation or around drying-off. Prior isolation of Staph. aureus and slight decreases in milk yield were two factors that interacted but both were strongly and positively related to clinical Staph. aureus. Staph. aureus mastitis typically had a subclinical debut, and increasing degrees and duration of inflammation decreased shedding of this pathogen. Streptococcus dysgalactiae (9% of the cases) mastitis was typically persistent virulent and manifest in periods of lower cow resistance. More patterns of subclinical and clinical Str. uberis mastitis (23% of the cases) seemed to be present.
Asunto(s)
Alimentos Orgánicos , Mastitis Bovina/epidemiología , Leche , Animales , Bovinos , Dinamarca , Infecciones por Enterobacteriaceae/veterinaria , Infecciones por Escherichia coli/veterinaria , Femenino , Lactancia , Modelos Logísticos , Mastitis Bovina/microbiología , Factores de Riesgo , Infecciones Estafilocócicas/veterinaria , Infecciones Estreptocócicas/veterinariaRESUMEN
The effect of planned dry period lengths of 4, 7, and 10 wk on subsequent lactational yield was estimated with 366 cows in an experiment in which dry period was manipulated independently of milk yield prior to drying off. In two herds, all three treatments were compared within herd; in six herds, two treatments were compared within herd. Compared with a 7-wk planned dry period, a 3-wk decrease lowered the level of milk production by 2.8 kg of 4% FCM/d in the first 84 d of the subsequent lactation, whereas a 3-wk increase raised the level of milk production by .5 kg/d. In the first 168 d of the subsequent lactation, the difference between 4-wk and 7-wk planned dry periods was 2.7 kg/d, and the difference between 7- and 10-wk periods was .4 kg/d. There was no indication of interaction among planned dry period length and lactation number, days open in previous lactation, previous milk yield, breed, or health status with respect to effect on subsequent lactational yield.