Risk factors associated with health disorders in sport and leisure horses in the Netherlands.

Horses are used for a wide variety of purposes from being used for recreational purposes to competing at an international level. With these different uses, horses have to adapt to numerous challenges and changes in their environment, which can be a challenge itself in continuously safeguarding their welfare. The objective of this study was to assess the prevalence of health disorders with clinical examination and identify possible risk factors of health disorders affecting horse welfare in professional husbandry systems in the Netherlands. With the use of fixed protocols for recording health aspects in horses, 150 horse farms voluntarily participating in the study were assessed by trained assessors. On each farm, 20 horses were clinically examined, in total almost 3,000 animals. This study recorded on the basis of the clinical examinations: the respiratory system (i.e., abnormal breathing [1%], coughing [1%], nasal discharge [1.9%]), body condition (i.e., 18.8% fat body condition and 6.4% poor body condition), locomotion (14.5% exhibited irregularity of locomotion and 4.8% were lame), back palpation (a light response [22.6%] and moderate to severe response [8.4%]), mouth (i.e., irregularities on mouth corners [3.4%] and bars [3.4%]), and ocular discharge (12%). Risk factor analysis, stepwise using mixed model regression, demonstrated several risk factors for health aspects. Horses used for instruction (riding lessons) were almost two times more at risk to develop moderate to severe back pain compared to horses used for recreation (odds ratios [OR] = 0.54) or for competition (OR = 0.61). Horses used for instruction (riding school lessons), breeding, or recreation all had a higher risk for irregular locomotion or lameness compared to competition horses (OR = 0.42, OR = 0.55, OR = 2.14, respectively). Horses used for recreation were more prone to have a higher BCS compared to horses used for breeding (OR = 3.07) and instruction (OR = 2.06). The prevalence of health problems and the identified risk factors are valid for the horses in the present study in which farms voluntarily participated. Furthermore, the results may provide the basis for horse welfare and health programs on farm and horse industry levels. With the development of a valid welfare monitoring system for the horse industry, the welfare of horses can be increased through improving awareness and stimulating changes in management.

The relationship between milking interval and somatic cell count in automatic milking systems.

The aim of this study was to explore whether, during automatic milking, milking interval or its variation is related to somatic cell count (SCC), even when corrected for effects of production, lactation stage, and parity. Data on milking interval and production level were available from the automatic milking systems of 151 farms. Data on SCC, parity, and lactation stage were derived from dairy herd improvement records of the same farms. Mainly due to incomplete records, data of 100 farms were used in the final analysis. For every cow, only 1 test day was used in the final analysis. Milking interval, the coefficient of variation of milking interval, production rate, the difference in production rate between short- and long-term, parity, days in milk, and some biologically relevant interactions were used in a linear mixed model with farm as random variable to assess their association with log10-transformed SCC. None of the interactions was significantly related to SCC, whereas all main effects were, and thus, stayed in the final model. The effect of milking interval was, although significant, not very strong, which shows that the effect of milking interval on SCC is marginal when corrected for the other variables. The variation in milking intervals was positively related with SCC, showing that the variation in milking interval is even more important than the milking interval itself. In the end, this study showed only a limited association between milking interval and SCC when milking with an automatic milking system.

Relationship between udder health and hygiene on farms with an automatic milking system.

Poor hygiene is an important risk factor for reduced udder health. Because the teat cleaning process is done automatically on farms with an automatic milking system (AMS), hygiene management might differ. The aim of this study was to determine the relationship between hygiene and udder health on farms with an AMS at the farm level as well as at the cow level. Information on hygiene and udder health was collected on 151 Dutch dairy farms with an AMS. Teams of 2 veterinary students collected data with the use of a partially open-ended questionnaire and scoring protocols for hygiene of the cows, cleanliness of the AMS, and functioning of the AMS. Milk production records from the Dutch dairy herd information association were also collected. Stepwise general linear models were used to analyze the relation between hygiene and udder health at farm level. Dependent variables were average herd somatic cell count (SCC), the average percentage of new cows with a high SCC, and the incidence rate of clinical mastitis, all in the year preceding the farm visit. The annual average herd SCC was positively related to the proportion of cows with dirty teats before milking and the proportion of cows with dirty thighs. The annual average percentage of new cows with a high SCC was positively related to the proportion of cows with dirty teats before milking and the proportion of milkings where teats were not covered with teat disinfecting spray by the AMS. The annual incidence rate of clinical mastitis was positively related to the frequency of replacing the milking filters. At the cow level, hygiene scores of the udder, thighs, and legs (range 1 to 4, where 1 is clean and 4 is very dirty) were related with cow SCC from the milk production test day closest to the farm visit using a general linear mixed model. The relationship between cow SCC and the hygiene score of the udder was positive.

Recovery of cow teats after milking as determined by ultrasonographic scanning.

Recovery time of teat tissue after milking was determined by ultrasonographic scanning. Teat-canal length, teat-end width, teat-wall thickness, and teat-cistern width of 18 cows varying in parity and lactation stage were measured in duplicate before and directly after milking and every hour for 8 h. The ratio between teat-wall thickness and teat-cistern width was calculated. The effects of time after milking and teat position on the teat parameters were estimated using REML models. The mean differences of ultrasound measurements of teat-end width and teat-canal length between duplicate measurements were 3.6 and 8.2%, and between d 4.4 and 7.8%, respectively. Teat-wall thickness and teat-cistern width were more variable (15.3 and 22% between duplicates, and 13.6 and 19.9% between days, respectively). Teat recovery after milking took a considerable amount of time: teat-wall thickness, 6 h; teat-end width, >8 h; teat-canal length, >8 h; teat-cistern width for rear teats, 3 h, and front teat 8 h, and the ratio of teat-wall thickness and teat-cistern width, 6 h. Ultrasonographic scanning of teat parameters was a useful tool to study teat changes caused by milking. Teat recovery took more time than expected, which makes caution necessary when increasing the milking frequency.

Relationship between teat-end callosity and occurrence of clinical mastitis.

A longitudinal study in 15 herds, with a total of 2157 cows, was conducted to examine the relationship between teat-end callosity (TEC) and the incidence of clinical mastitis. During the 1.5-yr study period, clinical mastitis was diagnosed by the farmers based on clinical signs. Teat-end callosity was scored every month according to a teat-end callosity classification system, which discriminates between teat-end callosity thickness (TECT) and roughness (TECR). Differences in TECT between healthy and clinical mastitis quarters within infected cows were small but significant 3 mo before (0.13 higher), in the month during which the clinical mastitis occurred (0.08 higher), and in the following 2 mo (0.06 and 0.05 higher). To compare TECT and TECR between cows with and without clinical mastitis, 199 cows with clinical mastitis were paired with control cows based on herd, days in milk, and parity. Clinical mastitis cows had more TEC than their healthy herd mates, particularly when clinical mastitis occurred between the second and fifth months of lactation. Clinical Escherichia coli mastitis in the second or third month of lactation occurred in cows with less TEC than in cows with clinical mastitis caused by other pathogens. Clinical culture-negative, yeast, Klebsiella pneumoniae, and Enterobacter aerogenes mastitis cows had more TECT and TECR than other cows with clinical mastitis in the same month of lactation. Pointed teat ends had higher TECT and TECR than flat or inverted teat ends. Teat-end callosity thickness increased with a higher milk yield at peak production.

Classification and longitudinal examination of callused teat ends in dairy cows.

To examine the development of teat end callosity thickness and roughness in early lactation and to quantify cow factors of interest, a system to classify teat end condition was developed. A distinction was made between rough and smooth rings around the teat orifice. In addition, a classification of the degree of callosity was developed. Kappa coefficients for the repeatability of scoring by this classification system by different workers were 0.71 for teat end callosity thickness and 0.86 for teat end callosity roughness. The teat end callosity classification system was used for a longitudinal study with 40 cows during the first 14 wk of lactation. Models were built to predict teat end callosity thickness and roughness, machine-on time, and milk yield. For the response variables, teat end callosity thickness, machine-on time, and milk yield, the consecutive measurements appeared to follow a lactation curve model with a subject-specific general slope and intercept. Teat end callosity increased rapidly the first 8 wk. Cow factors such as days in milk, parity, machine-on time, and teat end shape were associated with the degree of teat end callosity, and the probability of the callosity ring to become rough. Teat end callosity thickness did not decrease within the 14-wk trial period for most teats. Pointed or round teat ends showed more callus than inverted teat ends. Longer machine-on time resulted in a higher probability of the callosity ring to become rough. Rear teats showed less callosity than front teats in this study.

Multivariate epidemiological approach to coccidiosis in broilers.

A retrospective, case-control study into risk factors of coccidiosis was undertaken using data from 189 broiler flocks. A case flock was defined as a flock in which at least one bird had intestinal lesions on 1 of 6 wk in a 42-day cycle. Flocks wherein such birds could not be detected were defined as controls. There were 187 variables, measured or derived. These were assigned to subsets of data, each subset being a group of variables representing related information. Uni- and bivariate analyses were performed in each subset. Variables and interactions that were significant in these analyses were entered into a multivariate model across subsets. In the final model, seven variables appeared to be significantly associated with detecting lesions in birds of a flock. Differences among breeds covered a range of about an 80-fold change in risk of being a case. At intermittent lighting, the risk of being a case increased about sevenfold compared with continuous lighting. A higher initial (Week 1) environmental temperature decreased the risk of finding lesions in a flock (about .8-fold per degree Celsius). This risk was also lower at a lower average aerial ammonia content (below versus above 14 ppm) and higher maximum carbon dioxide content (above versus below .4 vol%) changing the risk about .3- and .4-fold, respectively. The risk of being among cases increased with more litter (about twofold per kilogram of litter per square meter). Flocks in houses of 600 to 800 m2 were about 9.8 times more at risk of being scored as lesion-positive than those in smaller houses.(ABSTRACT TRUNCATED AT 250 WORDS)