Improving Hide and Skin Quality
a project funded by the European Commission
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Newsletter No 4 (2000): Overview of Current and Recent Research
All countries in the consortium are involved in some type of hide improvement activity. While some are involved mainly in information exchange and publicity, there is a significant amount of research and investigation work being carried out, with most of the work revolving around a limited number of recurring themes. These are
Some examples of current work in these areas are reported in the more detailed articles in this Newsletter, and these topics will certainly be included in the recommendations for further research (to be featured in Newsletter Number 6). The following Sections give a summary of the activities in each of the Partner countries.
The main area of research work over recent years has been on the cattle follicle mite, Demodex bovis and more recently the emphasis has been on publicity and information, with the publication of a booklet on hide improvement aimed specifically at the farming sector.
Areas of recent activity have been work on icing of hides as a means of short-term preservation, the reduction of flay and trimming damage at the abattoirs, and the development, by a commercial company, of a prototype system with the potential for identifying and tracing hides and skins through the distribution chain (further details are given in this newsletter).
The most recent research work has concerned a study of the defects caused by both sucking and biting lice and the causes of the light spot defect in leather. The emphasis of current work is based upon publicity to farmers, and there is a national PR campaign aimed at agricultural colleges. The association has recently published a booklet on "Correct
handling and transportation of cattle" and has introduced an award for the development of the best draft for a programme combating ectoparasites on cattle farms.
The main activities in Greece are general publicity and information exchange.
Due to Italys large demand for raw material, a priority for the Italian tanning industry is to develop systems to improve hide and skin quality in supplying countries - in particular the former USSR and East and South Africa. Here the goal is to set standards, by pictograms and other tools, to link the purchasing contract to quality control tolerances. Regarding technical research, there are projects to improve the physical/mechanical performance of hides and skins and increase their useful area, through experimental feeding regimes, definitions and characterisation of different breeds to define an ideal hide and skin model, and the testing of novel short term preservation systems with a low environmental impact.
The main recent work has been to explore a system of tracing hides and farm protocols as possible bases for incentive schemes. This is reported in more detail in this newsletter.
The main work carried out recently in Spain has been on reducing butcher strain caused during "pulling" of sheepskins, on optimising drying temperatures for hides and skins to minimise damage, and preservation methods using less salt in conjunction with biocides.
Recent activities have been on reducing lice damage to hides, icing systems for short term preservation, and development and progress of the incentive based "Golden Hide" scheme, which is now reported to be more than covering its costs.
The main activities in UK are related to dirty cattle, parasite (particularly lice) damage to hides, and the potential for farm assurance schemes to provide financial incentives for improving hide and skin quality. These are covered in the more detailed reports in this newsletter.
The production of high quality leather depends upon the complete absence of defects on the grain. The defects commonly seen on hides result from ectoparasite infestation, scratch, dung and Ringworm. Potentially, all of these defects can be reduced or controlled by modifications during the rearing period. However, farmers see little or no perceived benefit to improving hide quality as they are unaware of the hides value. Therefore a vital element of a sustainable hide improvement system is to establish some form of direct reward to the farmer (and abattoir) which relates quality to the price received.
Different systems apply in different situations, and Newsletter Number 3 outlined the reward systems in Sweden, New Zealand and Australia. The object of this project was to develop the basis of a system that could operate in the complex UK system, where there are around 150,000 livestock farmers and some 350 abattoirs.
The aim of this project is to measure and quantify the increase in value of hides produced under "improved" conditions when compared to "standard" hides (Figure 1) and to develop protocols which can be incorporated within a more general Farm Assurance Scheme, with the objective of rewarding farmers and abattoirs by establishing a higher market price for following practices which produce better quality hides and skins.
Figure 1. Overview of project elements
The project began with a questionnaire to farmers; the 365 responses helped focus on the risk factors for hide quality, including:
Questionnaire results (Figure 2) showed little difference in fencing methods used between the regions, with barbed wire being used either exclusively in 9% of cases, or in conjunction with other fencing methods in 79% of cases. This could reflects the current high incidence of scratch damage of UK hides, estimated at 70-90% of hides affected. Electrical fencing was used exclusively in 6% of cases and natural hedges/walls in 5% of cases. Electrical fencing is preferred by tanners as it presents reduced risk of scratch damage but exclusive use of electric fencing is seldom found on UK beef farms.
Figure 2. Fencing types used
The results show 78% of all respondents dehorning, and 89% of producers that dehorn their cattle do so at less than 6months.
Infestation of cattle with ectoparasites results in significant damage to hides and a marked reduction in their value. The most notable skin infestations are due to lice and ringworm. Currently in the UK it is estimated that 50% of hides exhibit damage attributed to lice and 10% due to ringworm.. The results in Figure 3 show that producers underestimate levels of infestation in cattle.
Winter 97 50%(n=24) 20% (n=922) (Milnes & Green, 1999) Winter 98 58%(n=12) 19% (n=365) (BLC, 1999)
Figure 3. Comparison of producers &
Opinion of lice infestation of cattle
The questionnaire results shown in Figure 3 demonstrate the widespread use of clipping to clean cattle pre-slaughter. 41% of producers surveyed used clipping exclusively and 21% used clipping in conjunction with straw, giving a total of 62% using clipping as the preferred method to clean cattle. 35% of producers used straw exclusively or considered their cattle clean enough to go to slaughter without an additional cleaning required. It is these producers that would supply hides of a high standard of cleanliness and reduced damage from clipping.
Figure 4. Cleaning Method
The information gained from the questionnaires, farm visits and wet blue gradings has being utilised to produce a "best practice" protocol for the production of quality hides and skins.
Damage caused as a result of lice, scratch, Ringworm and dung contamination all have significant financial implications for the tanner and livestock producer. The benefits of treatment are often not apparent to the farmer and require effort on his part. However, this work has demonstrated that on farm improvements led to increased leather quality and value for the tanner. The challenge for the future is to secure a supply of this raw material by encouraging farmers to take a more active role in production in order to realise the true potential value of their product.
Work in France has developed the "Landata" system, which would permit traceability from the live animal to the finished leather
To measure and to improve the true quality of material supplied through the chain, from the farm to the consumer, the leather industry has to develop a system to allow the individual identification of hides or skins from the farm and slaughterhouse right through to the leather users.
The current events connected with the BSE and the utilisation of by-products confirm the need for a secure traceability methodology and this is precisely what is claimed by this system.
The principle is based on the oldest and most efficient technique for marking leather, namely perforation. This ensures that there is no risk of loss by detachment as found with labelling. Resistance to chemical treatments is guaranteed, and furthermore, perforations are preserved through fleshing, splitting and shaving operations. The identification is represented by an individual matrix of perforations effectively giving a binary code (which is claimed to give an inviolable code with no reading errors).
Prototype equipment has been developed for marking and automatic reading of the identification code. The image interpretation system allows for deformation of the marking during leather making processes.
The study took place on cattle hides, calf and sheepskin using marking equipment installed in an industrial abattoir and reading equipment in different leather factories. Reading trials have been done in wet blue, crust and finished state on soft, firm, aniline or pigmented leathers. The results have shown that of the 500 hides marked at the abattoir (1,000 markings), the average correct readability at the finished leather stage is between 98 and 98.5 %.
With this unfalsifiable system, the researchers offer the opportunity to ensure quality control of skins from breeding to finished leather. The perforated matrix, resistant to all tannery operations and distortions through the process will be recreated by the reading programme.
It is claimed that first tests and industrialisation studies have shown that this is a powerful and unique technique to trace raw hides from abattoir to finished leather utilisation. Reported response from the leather sector is that the prototypes can be made into saleable products and the patent owner is currently looking for a partner.
A collaborative project (EU1062 EUROCLEAR) involving Norwegian, Swedish and UK partners has been carried out to develop a better understanding of the causes of light spot and fleck on leather and to evaluate methods of reducing the problem in tanneries.
The UK part of the project aimed to establish the feasibility of introducing a practical programme into national herds to eradicate light spot and fleck damage through the control of ectoparasites, in particular, lice.
Specifically, the objective of this work was to;
Establish a link between lice infestations, treatments and levels of hide damage.
Monitor and define the fundamental aspects of ecotoparasite damage to cattle hides.
Assess practical systems for ectoparasite control.
Running throughout the project was a two year experiment designed to establish the link between lice infestation and light spot damage on leather. This experiment (shown diagrammatically in Figure 1) also investigated the effects of treatments on reducing lice infestation and the effect on reduction of light spot on the subsequent leather.
Figure 1. Outline of cattle treatment regime over winters 1997-98 and 1998-99
Results from this experiment have proven the link between the presence of lice and the occurrence of light spot on leather. The studies have also found that the occurrence of light spot can be reduced on animals that have been infested with lice. This was achieved by clearing the animal of the infestation and reductions were seen in light spot, both in terms of severity and extent of cover (see Figure 2. and Figure 3.).
|Figure 2. The effect of
the presence of lice on the severity
of light spot on processed calf skins (first winter animals)
|Figure 3. The effect of
the presence of lice on the area of
light spot on processed calf skins (first winter animals)
This work suggests that a treatment regime which cleared lice 6 or 12 weeks prior to slaughter would reduce the extent of the light spot damage and hence, increase the value of the resultant hide.
Animals slaughtered in the first year, following the winter housing period, formed four groups: Lice free, Lousy, Lousy cleared 6wks and Lousy cleared 12wks.
Those animals that were kept lice free gave hides with consistently lower levels of lightspot and fleck, both in terms of area and severity of damage. In addition, they also gave higher commercial grades when compared with the other three groups. In contrast, the animals that were kept in a lousy condition were the most extensively damaged and gave the lowest grades of the four groups.
Of the remaining two groups that were lousy and then treated to clear the existing infestations, those animals that were left twelve weeks prior to slaughter had significantly improved leather quality when compared to the untreated controls. The group that were cleared for six weeks demonstrated only a slight improvement in quality.
Figure 4. Tannery gradings of hides with known lice history
Animals were taken on to full term and slaughtered at the end of the second winter and formed eight groups:
Lice free; lousy; Lousy cleared 6wks; lousy cleared 12wks; Lousy/lice free; Lice free/lousy; lice free/lousy cleared 6wks; lice free/lousy cleared 12wks.
The results from the gradings of the second year cattle revealed that lice at the time of slaughter significantly increased the amount of damage seen on the hide. Animals kept lice free throughout their lives gave hides with the least amount of damage and the highest commercial grades. Animals that had been infested with lice at some point during their lives and were subsequently cleared prior to slaughter, demonstrated improvements when compared to animals that were lousy at slaughter Figure 4).
Whilst the results demonstrated improvements in leather quality in animals that were cleared prior to slaughter and left for the appropriate time, these results were inferior to cattle treated shortly following birth and subsequently kept lice free. This clearly promotes the proactive approach to treatment. However, the improvements seen in "cleared" cattle were significant and this treatment strategy could realistically be incorporated into the production cycle. The increase in value of these hides would outweigh the cost of the treatments involved, thus making the strategy viable for both the farmer and tanner.
|Recently, a rise in lightspot levels has been noticed in the late summer during August and September and this damage was found to be linked to the biting fly Stomoxys calcitrans (right). This fly is prevalent in the summer and feeds by piercing the hide to obtain a bloodmeal. When hides are initially examined the damage resembles lice related lesions. However, under the microscope the damage was seen to have sharper boundary edges, a more consistent size and shape and had penetrated into the corium, beyond the superficial grain enamel associated with lice damage. It is concluded that the apparent late summer rise in lightspot in UK raw material is due to Stomoxys and not lice.||
Figure 5. The biting fly Stomoxys calcitrans
|Cattle housed over winter frequently become covered
in dung contamination, leading to erosion of the grain
enamel and subsequent downgrading. In addition, dung
covered hides also represent increased cost to the tanner
in the form of extended process times and increased
effluent discharge. It has also been demonstrated that
animals slaughtered in a "dirty" condition lead
to carcasses with high levels of bacteria that represent
a hazard to human health due to poisoning by E coli 0157.
In the UK, this led to the establishment of a five point system for assessing livestock cleanliness, with 1 and 2 being very clean and 3, 4 and 5 being dirty and hence unacceptable for slaughter. These strictly enforced guidelines for cleanliness have resulted in a significant reduction in the number of dirty animals presented for slaughter (Figure 1). This reduction has also been apparent in UK tanneries where an annual survey of levels of dung contamination has shown an encouraging downward trend (Figure 2).and Tables 1-3.
Estimated 20kg of dung on a hide that has gone through the UK abattoir system
|Figure 1. Number of UK
cattle rejected for slaughter as
"too dirty" by Meat Hygiene Service officers
|Figure 2. BLC data showing
the reduction of dirty
bovine hides at UK tanneries
More recently, work conducted by BLC and ADAS (Agricultural Development & Advisory Service) on behalf of MAFF has traced "dirty" cattle through the production chain to study the parameters that influence dirtiness. These factors were found to be age, coat length (Table 1), journey distance/time and clipping of the coat to remove dung. Further projects are now taking place to measure similar factors for sheep and to investigate the transmission of Escherichia coli 0157 through livestock populations.
The figures in Tables 2 and 3 indicate a longer term improvement in all regions of the British Isles, although the relatively small numbers of hides inspected from some areas (e.g. Scotland in 1999/2000) contribute to some statistical "blips" in the figures. The slightly higher levels of dung on ox hides reported for England over the last winter are probably explained by a statistical variation and by the inclusion of data for February (from previous records, the worst month for dung) and March, while there are so far no figures for these months on hides from Scotland and Southern Ireland
The results demonstrate that the delivery of cleaner cattle to the abattoir can be achieved by exercising stricter controls, which, in turn, enforce better husbandry practices. The future challenge is to develop housing, feeding, handling and transport practices which deliver the results in the most efficient manner, do not involve damage to the hide, and do not involve risk to the farmer or compromise animal welfare (for example through clipping or shearing the cattle just before slaughter).
Table 1. Effect of length of coat on MHS score
*a five point scale for
assessing the cleanliness of
livestock. Increasing score indicates a rise in level of
contamination present on the hide/skin of the live animal.
Table 2. Dung on UK Hides 1997-200
|Amount of dung/hide (kg)||1.4||0.3||1.3||0.3||1.0||0.6||0.3||0.4|
|% of hides with dung||47%||15%||49.2%||19.2%||46.1%||30.0%||28.1%||22.0%|
|% of hides with over 4.5 kg of dung||11%||1%||8.6%||0.7%||6.3%||3.6%||0.14%||1.3%|
Table 3. Yearly comparison of Average amount of dung per ox hide by country
The Dutch Partner undertook an integrated chain project to trace the quality of bull hides from the farms through a slaughterhouse to the tannery. This project involved a survey at 22 bull rearing farms and the assessment of 824 bull hides. The hide quality was assessed at the tannery, by standard measures and the results were linked to individual animals at the farms. The scale for hide quality ranged from 10 (worst class) to 80 (best class). From this data the following protocol was developed.
Hide quality of purchased calves
Bull calves have a number of skin problems at the moment of purchase, which can be detected at the point of hide quality assessment at the tanning company. Most important problems are cured wounds, due to damaging of the skin e.g. from barbed wire. Another frequently reported problem is the presence of endo- and ecto-parasites, which cause small pinholes or damaged spots (from infections) in the tanned hide. Ecto-parasites can cause considerable skin damage at the farm, and are also frequently associated with a lower growth rate and a higher feed conversion ratio.
In this survey the hide quality of straw-reared bulls was compared to that of slat-reared bulls. The hides from straw-reared bulls (41 hides) scored 2.5 points higher than the hides of slat-reared bulls (318 hides).
Some of the animals at the farms were treated with chemicals to prevent parasites. The hide quality of the treated group was compared with that of the non-treated group. The difference in hide scores (250 hides) between treated animals and non-treated animals was about 9 points.
Another treatment that is frequently applied is shaving of the bulls. As the conditions for lice and mites are better in a long-haired coat, shaving of bulls is a preventative measure that lessens the risk of ectoparasitic infection with lice or mites. Bulls that were shaved at the inspected farms, were generally shaved only on their backs in a 15 to 25 centimetres broad band from front to rear. The hides from non-shaved animals had a hide score of 26, whereas the hides from shaved animals had a score of 38.
Dehorning results in a quality improvement of 5 points. Hide scores range from 34 at farms with horned bulls to 39 at farms that dehorn the bulls. Dehorning is not always practised, because farmers find it a difficult and dangerous job.
In general, special measures at the farm such as treatment against parasites, shaving and dehorning give positive effects on quality of the hides. In addition to this, these measures can be expected to improve growth rates. Therefore the total economic benefit of such treatments can be considerably higher than the financial benefits of hide quality improvement alone.
Interpreting the results indicates that a better hide quality is not due to one separate measure, but caused by several different measures at a time, because in practice these measures are often combined.
Important subjects according to farmers are - for scratch - care when loading, moving cattle, avoidance of sharp surfaces in housing, dehorning and - for cleanliness - using sufficient straw.
A major quality improvement can be achieved in Dutch hides. Hide quality, in this survey, varied 16 points on a scale from 10 to 80 between the "worst" farmer and the "best." Farmers, in order to achieve a good hide quality, will have to apply a number of measures as a whole package and there is some evidence that higher returns for hides and growth rates can compensate farmers for the additional production costs.
The main recommendations forming the basis of a draft protocol are:
Only buy bulls that are treated against ectoparasites from birth and dehorned at an age of 1 to 3 months; also avoid the use of barbed wire (these may be difficult because many calves are imported from other countries).
House/bed on straw (this implies costs because farms mainly use slat systems)
Preventative treatments especially:
Use injections or pour on treatments against parasites
Washing of animals with an anti-parasitic drug.
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