Efficacy of Currently Recommended Control Measures for Lameness in Dairy Cows

Summary

Lameness is a multifactorial condition, the principal factors influencing its development being genetics, nutrition, environment and management. The objectives of the studies reported here were:

1. To determine the incidence of lameness on selected Irish commercial dairy farms,
2. To identify and to quantify risk factors associated with lameness on Irish dairy farms and
3. To evaluate the efficacy of recommended control measures for lameness with the aid of information obtained through (i) and (ii).

• The average number of animals which became lame per six month period (Jan-Jun or July-December) on 14 commercial dairy farms was between 12 and 16 per 100 cow s. On individual farms the figure could be as high as 3 1 per 100 during any six month period.
• White line disease was the most common cause of lameness with sole ulceration being the second most common.
• Poor maintenance of roads with little use of top dressing and the presence of concrete roadways on farms were both associated with a detrimental effect on lameness incidence. Thus, prevention of lameness at pasture e entails maintaining roads in good condition and, if concrete roads are used for cows, care must be taken to ensure that the junction between the concrete and the dirt road is maintained in good condition and that the concrete is maintained free of grit.
• Cubicles on most farms have not been upgraded sufficiently to provide adequate cow comfort. Many are too small for the size of cows housed and bedding is frequently insufficient. Uncomfortable housing conditions resulted in less lying behaviour and more standing half-in cubicles.
• Restricted feed space was associated with more lameness. Experimental studies suggested that this effect was likely to be mediated through increased aggression between animals.
• Higher levels of concentrate feeding correlated with more lameness. Increasing fibre in the diet in the form of sugar beet pulp appeared to protect against lameness. There was some evidence that feeding maize silage may increase lameness incidence but this effect requires further study.
• Cows housed in all space-sharing cubicle designs tested showed good lying times. The finding that cows will reduce use of cubicles in order to stand on a soft matted area suggests that even spacesharing cubicles may not always provide sufficiently comfortable conditions for cows. It also reinforces the findings of work at Moorepark and elsewhere those cows do not like standing on concrete in addition to the fact that it can be detrimental to claw health.

All of the above findings suggest that lameness incidence could be reduced by maintaining roads in good condition, avoiding the use of concrete if possible, providing comfortable housing conditions and avoiding all design features which reduce cubicle occupancy and which increase aggression between cows.

Incorrect cubicle dimensions can lead to cows spending long periods standing half in cubicles. This may be associated with lameness.

Introduction

During the three years from 1991 to 1994, a series of experiments were carried out at Moorepark Research Centre investigating the role of housing and behaviour in lameness development. These studies were undertaken because there was little information available on this aspect of lameness in comparison to the numerous studies on the influence of nutritional factors on foot health. Following these experimental studies, a detailed epidemiological study on commercial farms was begun at the end of 1994. The emphasis in this study was again on environmental rather than nutritional factors and some of the methodology used during the earlier experimental studies was applied to the on-farm investigations.

Epidemiological studies have been carried out in a number of countries but it was considered that the major differences that exist between Irish dairy production systems and those used elsewhere justified doing such a study in the Moorepark area. In addition, investigations into environmental factors affecting lameness development were more detailed and extensive than in previously reported observational studies. During the course of the on-farm study, questions arose which could not be adequately addressed through an epidemiological study alone. Therefore, some complimentary experimental studies were completed in Moorepark.

Lameness is a multifactorial condition, the principal factors influencing its development being genetics, nutrition, environment and management. It is difficult to determine the relative importance of these factors as each one can affect the expression of the other depending on the situation on a particular farm. Control of lameness is therefore considerably more difficult than control of other disease conditions caused by a single agent such as one bacterium or virus.

The objectives of the studies reported here were: (i) to determine the incidence of lameness on selected Irish commercial dairy farms, (ii) to identify and to quantify risk factors associated with lameness on Irish dairy farms, and (iii) to evaluate the efficacy of recommended control measures for lameness with the aid of information obtained through (i) and (ii). The report is divided into sections, each dealing with one aspect of the results of the study and one in which the conclusions are drawn.

Lameness Incidence and Conditions Causing Lameness

Fourteen commercial farms in the north Cork area were chosen for this study with the aid of the Farm Relief Services and local veterinary surgeons. The principal criteria for inclusion were farmer willingness to co-operate and use of the Farm Relief Services for hoof care. It was not possible to conduct a random survey, as farmer co-operation was essential in order to record lameness events and also to allow for the frequent visits and studies on the farms. The study was carried out over two years on 14 farms. Herd size ranged from 53 - 200 cows (average 92). Most herds were spring calving although three herds had a proportion of autumn calving animals (25%, 40% and 50% respectively).

Lameness was recorded at the time of herd foot trimming in December / January and the farmer recorded all cases of lameness which developed during the rest of the year. Lameness was recorded half-yearly because lameness in the first half of the year is influenced by factors relating to calving, housing and pasture conditions. Lameness in the second half of the year is influenced mainly by conditions at pasture. Insults sustained by the claw injure the quick immediately but effects may not be seen at the sole surface until 2-3 months later as it takes this length of time for horn to grow from the quick to the sole surface. Thus, effect of housing in November may not manifest as claw health problems until January or February.

Table 1 records the mean incidence and type of cases causing lameness during 1995 and 1996. Sole ulceration and white line disease were the conditions most frequently diagnosed as the cause of lameness. The category 'other' included conditions of the interdigital skin such as foul and digital dermatitis (Mortellaro). Conditions affecting the limb as distinct from the claw were also included under 'other' but the number of cases was small. The final column in the table records the total 'animal incidence' which is the percentage of animals affected by lameness in the relevant 6month period. This is lower than the case incidence as some animals could be affected by two different conditions in the same period or could be affected by the same condition more than once.

Table 1: The mean case and animal incidence of lameness on 14 commercial dairy farms for the first and second 6-month periods of 1995 and 1996.

As can be seen from Table 1, white line disease was the most significant cause of lameness in all half-yearly periods except the first half of 1996. This is different from other UK and European studies where sole ulceration is usually recorded as the top cause of lameness in dairy cows. The difference is probably due to the seasonal calving pattern in Irish herds.

Autumn and year-round calving is more common in other countries and sole ulceration is a particular problem when animals are housed, calve and receive a change in rations within a short space of time. Spring calving animals have time to adapt to changed housing and feeding conditions before they calve down. The grazing season in Munster is also considerably longer than in many European countries. White line disease is a common cause of lameness in animals at pasture as has been reported in countries such as New Zealand.

Foul-of-the-foot occurred in outbreaks on one or two farms each year and increased the numbers in the category 'other'. The outbreaks frequently occurred shortly after turnout to pasture and appeared to be associated with rough roadways or gateways. Although digital dermatitis was a problem on two of the farms, its occurrence in the other herds was sporadic.

Roadsurfaces on Farms and Lameness Development

Road surface characteristics were assessed twice as part of this study, once during a period of dry weather and once during a period of wet weather. On each farm, a 100-mm by 100-mm metal square was thrown at random (over the shoulder) at intervals of 5m along all farm roadways. Eight variables were recorded within the square, four of which reflected road composition (concrete, stones, fines, grass (as an indicator of upkeep of roads) and four of which classified the roads according to character (depth of penetration of a probe, unevenness, drainage and sharpness). Assessments on all roads were carried out by the same person.

For each road, the variables were weighted for the length of the road and its estimated usage by the herd. The mean values for all the roads on each farm were taken to represent the road profile of that farm. Factor analysis is a data reduction technique, which was used to condense the original 8 variables into three factors. The 14 study farms were then assigned scores, ranging from -2 to 2, for each of the three factors based on a linear weighted combination of the variables associated with that factor. Factor scores were used as determinants in a series of analysis of variance models with various measures of lameness as the dependent variables.

When the relationships between road surface materials were examined within farms, a negative association was detected between the use of concrete and the amount of fine material in roads (P<0.05). The prevalence of grass tended to be greater on farms with a high level of stones (P=0.051). When the four characteristics of roads were analysed, there was a high degree of correlation between sharpness and the prevalence of stones (P<0.001). Drainage was related to sharpness (P<0.01), the prevalence of stones (P<0.05) and the amount of fines (P=0.01). There was also a significant relationship between depth and unevenness (P<0.05).

Factor analysis identified three factors, which together accounted for 82% of the variance of the data. Factor 1 represented farms with roads containing a high level of stones and fine material and which tended to be sharp and well drained, farms represented by Factor 2 had the highest levels of concrete, the lowest of fines and significant levels of grass. The main attributes which loaded into Factor 3 were depth and unevenness and thus this factor represented farms with muddy tracks.

Factor 2 showed a significant correlation with a number of indices of lameness including overall animal incidence (P=0.037, r²=0.26). The association was strongest for lameness incidence in the period January to June (P = 0.016, r²=0.35), where it was present in both years of the study (Figure 1). Results from 10 herds, which kept detailed lesion records, indicated that white line disease was the main lesion affected by roadway conditions. There was a significant relationship between the incidence of white line disease and Factor 2 scores (P<0.05), particularly in the first half of the year (P=0.013, r²=0.5) (Figure 2).

Figure 1: The relationship between Factor 2 road scores and the average incidence of lameness on 14 farms between January and June in 1995 and 1996.

Figure 2: The relationship between Factor 2 road scores and the average incidence of white line disease on 10 farms between January and June in 1995 and 1996.

The method used for characterisation of road surfaces principally reflected the materials of which the roads were made and the state of maintenance of the roadways. Other studies in New Zealand and Australia have used similar criteria for classification of roads. Although many of the variables were assessed in a subjective manner, statistical analysis revealed logical correlation's between the variables, such as the significant correlation between sharpness and the prevalence of stones or the association between depth of penetration and unevenness. This suggests that the variables chosen were useful in the characterisation of the roads and that they were consistently assessed.

The three factors identified by factor analysis represented farms with widely different roadways. Factor 1 roads had the highest level of fine material and of stones, had no grass, were even and well drained. Thus, although these roadways tended to be sharp, they were also well maintained and thus there was no association between Factor 1 scores and lameness. In contrast, farms scoring highly for Factor 2 could be said to have poorly maintained roads and this was the only factor for which an association with lameness was detected.

State of track maintenance was found to be one of the most important variables in determining lameness level in a New Zealand study. The association detected between Factor 2 scores and lameness incidence was statistically strong and present in both years but the small size of the study population means that further studies are required to confirm the relationship observed. Both the absence of fines and the presence of concrete loaded highly into Factor 2, but regression analysis using the original variables indicated that the proportion of concrete roadways on the farm was the more significant determinant of lameness. However, as 9 herds had little or no concrete, the correlation between lameness incidence and concrete is biased by the results from those few herds using concrete. It is possible that farms making a high capital investment in concrete roadways tend to do less top dressing and therefore have a lower proportion of fines.

Factor 3 could also be said to represent farms with poorly maintained roads but, unlike Factor 2 farms, the roadways were soft (uneven and high depth of penetration) and contained no concrete.

The method described was useful in characterising road surfaces in relation to lameness development. Results suggest that a larger study should be carried out to confirm the importance of top dressing with fine material. Clarification is also needed as to whether walking/standing on concrete is detrimental to claw health. Concrete roadways, if present on farms, were always those roads nearest the milking parlour and cows therefore used these roads continuously during the grazing season.

On some farms cows were held on these roads for variable lengths of time before or after milking. It is possible that standing and walking on such hard surfaces adversely affected claw health as detrimental effects of standing on concrete have been shown for housed cows in previous Moorepark studies.

Another factor, which may account in part for the increased lameness seen on farms using concrete roadways, is that roadway conditions at the junction of the concrete and farm tracks were invariably extremely poor. It is likely that small pieces of grit were regularly carried onto the concrete on cows' hooves and these could then penetrate defects in the horn when trapped between the sole surface and unyielding concrete.

Martellaro is becoming increasingly common and may cause severe lameness.

Assessment of Housing Conditions on Farms

Data from large studies conducted in the UK and Europe indicated an association between different housing conditions and lameness incidence. Factors such as higher kerbs, poor bedding and slippery floors were associated with more lameness. However, there have been few studies in which cow behaviour has been recorded on a number of farms and related to housing conditions. The objectives of this part of the study were to record cow behaviour on farms over a number of hours and to correlate it with housing conditions and lameness measures.

Housing conditions such as cubicle design and dimensions were recorded by direct measurement and assessment. Behavioural data including lying, standing fully or half-in cubicles and rising and lying down behaviour was recorded for two three-hour periods on two consecutive nights on each farm. The percentage of time spent performing each behaviour was calculated for the total number of cows, taking into account the cow to cubicle ratio.

Only one farm had all space-sharing cubicles, 8 of the 14 farms had combinations of cubicle types and 5 farms had all Newton-Rigg or crossrail cubicles. Cow diagonal body length was measured on all farms and compared with cubicle length. Cubicles were too short on all except one farm and indications were that cubicles fitted against a wall should have been 2.3 m long on most farms.

Adequate bedding (mats or generous amounts of sawdust) was provided on only half of the farms. Housing conditions were overcrowded on 4 farms (>1.2 cows for every one cubicle) and cows had inadequate feed space on 5 farms (< 0.4 m per head). Three farms provided 0.6 m of feed space per head, which allows all animals to feed together and is considered optimal for cow welfare. Table 2 gives the median and minimum-maximum values for various behaviours recorded during the three-hour observations on farms.

Table 2: The percentage of 3 hours (median and min-max values) spent performing various behaviours by cows on 14 commercial dairy farms

Because of the small number of farms in the study, the effect of cubicle comfort on cow behaviour was not as readily detectable as in experimental studies. However, when herds were classified according to good and poor cubicle comfort, a relationship with cow behaviour could be detected. Herds where cubicle comfort was good (at least two of the three parameters cubicle size, design and bedding satisfactory; only one farm was satisfactory on all three counts) tended to show longer lying times (P=0.1), less half-in behaviour (P=0.09) and more ruminating while lying down (P=0.09) than those with poor cubicle comfort. Standing half-in cubicles indicates that cubicles are too short or possibly too narrow. High levels of ruminating lying down are thought to indicate good cubicle comfort as cows at pasture exhibit similar behaviour.

When the relationship between lameness and behaviour was examined, an association was detected between better claw health and increased standing fully in cubicles (P<0.05). Both major causes of lameness, sole ulceration and white line disease had lower incidences on farms where cows stood more in cubicles. This association has also been observed in recent Scottish studies. The mechanism behind this finding is not fully understood but it is possible that where cubicles are of sufficient length to allow comfortable standing, cows stand less in the passages and thus exposure of the hooves to slurry is limited. Other Scottish studies have confirmed the detrimental effect of slurry on horn structure and hooves that are maintained in drier, cleaner environments are likely to be less susceptible to injury, bruising or development of cracks in the white line.

It was more difficult to detect relationships between cow behaviour; cubicle design and lameness in this study than in experimental studies in which uniform groups of first calving animals are used. However, some indices of lameness tended to decrease as cubicle length increased although the relationship did not reach significance at the 5% level. This finding is consistent with those of previous experiments in which there was more lameness in animal's housed in short, narrow cubicles.

Increased levels of lameness were detected in herds where feeding space was restricted (r_s= -0.53, P = 0.075). This relationship was investigated further in an experimental study and results are presented in another section of this report.

Nutritional Factors and Lameness Development

Information on feeding practices was collected by means of a questionnaire. As stated previously, assessment of nutritional effects on lameness was not one of the primary objectives of this study as many other workers have examined the effect of nutrition on lameness. In addition, detailed feeding records were not available on most farms. However, the results of the small amount of analysis that was possible tended to support the findings of other studies.

There was a positive relationship between the amount of concentrates fed and the number of animals that became lame on a farm (P=0.05). When the particular conditions which cause lameness were analysed in relation to nutrition, it appeared that white line disease was more strongly related to nutritional factors than other conditions (P<0.09) but this may simply reflect the fact that white line disease was the most frequent cause of lameness on most farms. Fewer cases of lameness were associated with the feeding of sugar beet pulp (P<0.05) whereas feeding of maize silage tended to be associated with increased levels of some lameness indices.

Conclusions and Recommendations

1. The average number of animals which became lame in the first or second half of the year was between 12 and 16 per 100 cows but on individual farms the figure could be as high as 31 per 100.
2. White line disease was the most common cause of lameness with sole ulceration being the second most common.
3. Poor maintenance of roads with little use of topdressing and the presence of concrete roadways on farms were both associated with increased lameness incidence.
4. Cubicles on most farms have not been upgraded sufficiently to provide adequate cow comfort. Many are too small for the size of cows housed and bedding is frequently insufficient.
5. Uncomfortable housing conditions resulted in less lying behaviour and more standing half-in cubicles. Longer cubicles were associated with a decrease in some types of lameness. Results also suggested that cubicle dimensions which allow cows to stand fully in cubicles would help improve claw health.
6. Restricted feed space was associated with more lameness. Experimental studies suggested that this effect was likely to be mediated through increased aggression between animals.
7. Higher levels of concentrate feeding correlated with more lameness. Increasing fibre in the diet in the form of sugar beet pulp appeared to protect against lameness. There was some evidence that feeding maize silage may increase lameness incidence but this effect requires further study. It may be that farmers feeding increased concentrate levels also tended to feed maize silage.
8. Cows housed in all space-sharing cubicle designs tested showed good lying times. The finding that cows will sacrifice lying time to stand on a soft matted area suggests that even space-sharing cubicles may not always provide adequately comfortable conditions for cows.

Publications

Leonard, F.C., O'Connell, J. and O'Farrell, K. J. (1994). Effect of different-housing conditions on behaviour and foot lesions in Friesian heifers. Veterinary Record, 134, 490-494.

Leonard, F.C., O'Connell, J. and O'Farrell, K. J. (1996). Effect of overcrowding on claw health in first-calved Friesian heifers. British Veterinary Journal. 152, 459-472

Leonard, F.C., O'Connell, J. and O'Farrell K.J. (1996). Patterns of foot lesion development in replacement dairy heifers after housing and calving. In: Agricultural Research Forum, UCD, 28-Mar-1996, pp.185-186

O'Connell, J.M. and Leonard, F.C. (1997). Optimising winterhousing systems for dairy cattle. In: Advances in Behaviour Analysis.Dillenburger, K., O'Reilly, M.F. and Keenan, Mmm. (eds). UCD press.

Leonard, F.C., Stienezen, I. and O'Farrell K.J. (1997). Overcrowding at the feeding area and effects on behaviour and claw health in Friesian heifers (Abstract). Irish Journal of Agricultural and Food Research 36, 1 12.

Leonard, F.C., O'Connell, J. and O'Farrell K.J. (1997). Housing conditions and foot lesions in Friesian heifers. In: 5th International Livestock Environment Symposium, Minneapolis, US, 0 1-May-1997, pp. 250-257.

Leonard, F.C, Crilly, J. and O'Farrell, K.J. (1997). Analysis of farm roadway surfaces on dairy farms and the relationship with lameness (Abstract). Irish Veterinary Journal, 5 1 , 132.