Indian Journal of Animal Research

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Research Article

Indian Journal of Animal Research, volume 54 issue 6 (june 2020) : 768-774

Preparation of Cowslips from Rubber Wastes to Protect the Hoof of Animals - An Innovative Approach

M. Dhoolappa1,*, R.V. Prasad1, K.T. Lakshmishree1, S. Sundareshan1, B.U. Umesh1, M. Sampathkumar2
1Veterinary College, Karnataka Veterinary, Animal and Fisheries Sciences University, Bangalore-560 024, Karnataka, India.
2MyPol Pvt Ltd., Mysore-570 016, Karnataka, India.
Cite article:- Dhoolappa M., Prasad R.V., Lakshmishree K.T., Sundareshan S., Umesh B.U., Sampathkumar M. (2020). Preparation of Cowslips from Rubber Wastes to Protect the Hoof of Animals - An Innovative Approach . Indian Journal of Animal Research. 54(6): 768-774. doi: 10.18805/ijar.B-3660.

ABSTRACT

In dairy animals, lameness due to hoof and leg ailments is one of the major managemental problems which often results due to improper shoeing. It causes economic losses to the farmer and is also an important animal welfare issue. The main objective of the study was to design and develop affordable and durable Cowslips (rubberized shoes) for dairy animals to protect the hoof from injuries. The size range of the hooves was determined by measuring different hoof parameters on 46 dairy cows maintained at the institutional dairy farm. Based on the size-range data obtained, we designed and developed Cowslip of different sizes (small, medium and large) by using used rubber tyre wastes with the aim of withstanding an average body weight of the dairy animal (400-550 kg). Rubberized Cowslips prepared in the present study were evaluated for their retention periods and compared with the imported Cowslip devices. Rubberised Cowslip was found to be equally comparable with the commercial Cowslip in its efficiency and high affordability. These Cowslips will be helpful for the dairy farmers as a preventive device in the effective management of lame animals under field conditions. The data generated on morphometry of hoof would serve as a baseline data for designing indigenous Cowslips. Thus, effectively utilizing rubber obtained from scrap automobile tyre is not only beneficial in terms of cost reduction but has also the less ecological impact in keeping the environment clean and to achieve the better balance of natural resources.

INTRODUCTION

The tyre and footwear industries are the largest users of natural rubber. The majority of tyres in the market today has a limited life span and poses a challenge for ecologically-sound disposal at the end of the life span. The main characteristic of rubber is its property of high elasticity which allows it to undergo large deformations from which almost complete, instantaneous recovery is achieved when the load is removed (Beaty, 1992).
       
The tyres are made of vulcanized rubber, which is made by adding sulfur and heat to virgin rubber in order to make a tougher, more durable material but notoriously difficult to recycle (Blloshmi and Blloshmi, 2016). Since polymeric materials do not decay easily, disposal of waste polymers is a serious environmental problem. Large amounts of rubbers are used as tyres for airplanes, trucks, cars, two-wheelers, etc. But after the long run when these tyres are not serviceable and discarded, only a few grams or kilograms of rubber (<1%) are abraded out from the tyre. Almost the entire amount of rubber from the worn-out tyres is discarded, which again needs a very long time for natural degradation due to the cross-linked structure of rubbers and the presence of stabilizers and other additives. This poses two major problems: the wastage of valuable rubber and the disposal of waste tyres leading to environmental pollution (Basudam et al., 2000). Rubber cannot be softened or remolded by reheating unlike other types of thermoplastics polymer. Improper disposal of used tyres poses negative environmental impacts and it is also a waste of valuable materials and energy. Although there is scope to make good use of used tyres, it is rarely practiced.
       
The hoof of animals is considered as one of the most important locomotory body parts for supporting weight and for movement. The dairy animals are exposed to many physiological (internal) and environmental (external) insults affecting the structure and functions of the hoof. These include infectious, toxic and metabolic factors. All these must be considered when addressing the problem of lameness.
       
Lameness is one of the greatest economic concerns of the present dairy industry and its major ill-effects include pain, distress, loss in production, reduced reproductive performance and an increased risk of culling (O’Callaghan, 2002). It is reported that 60% of the herd may become lame at least once a year (Vermunt, 2004) and about 90-99% of lameness incidents occur due to hoof lesions (Van Amstel and Shearer, 2006). In the present scenario, it is also an important animal welfare issue (Keyserlingk et al., 2009). Clinical lameness is comparatively more concerned because of the high rate of culling (Schultz and Gröhn, 1999) and a marked reduction in milk yield (Green et al., 2002). Lameness is mainly due to hoof lesions arising out of laminitis (inflammation of the laminar structures of the hoof) in dairy animals. Apart from that, the occurrence of lameness may arise due to improper shoeing done by using nails.
       
The use of an orthopedic block applied to the healthy claw of a lame foot, judicious use of bandage or wrap, careful selection of parenteral or topical therapy and a treatment protocol to manage pain and promote recovery are key components of responsible management of lameness disorders in cattle.
       
The primary objective in the treatment of hoof lesions (especially sole ulcers) is to relieve pressure from damaged tissues due to weight-bearing. This can be achieved by the use of a Cowslip applied to the healthy hoof to relieve weight-bearing on a claw of hoof affected by a lesion. Relief from weight-bearing is also advantageous as a means to relieve pain and promote fast recovery. Relief from the pressure due to weight-bearing can be achieved by the use of a nail-free Cowslip applied to the healthy claw to relieve weight-bearing on a claw affected by a claw lesion (Pyman, 1997).
       
Cowslips are orthopedic shoes used for the treatment of lameness in cattle. They have a unique non-slip raised lattice sole that is of sufficient height to raise the diseased digit off the ground. Once applied to the healthy claw with the fast curing acrylic resin included in the kit, pain is alleviated, the cow’s mobility improves, weight is gained and milk yield increases. The Cowslips available presently in the market are manufactured using 100% recycled PVC.
       
The primary requirement for the preparation of the Cowslip is the morphometrical data of the hoof of dairy animals. However, the information on biometrical details of hoof and its volume in Indian dairy animals is not available. Therefore, it is necessary to document and characterize the biometrical features which eventually help to design Cowslips to protect hooves in dairy animals.
       
One of commonly available remedy for lameness due to hoof lesions is the application of orthopedic blocks such as Cowslips for adjustment of weight-bearing. Despite advances in the production and use of nail-free boots or Cowslips for horses and cows, the economically viable Cowslips have not been identified yet.
       
Therefore, the current research work was undertaken to study the morphology of hoof of dairy cows, to design, develop cheaper and eco-friendly Cowslips (nail-free shoes) from rubber tyre wastes and then to evaluate retention period of the Cowslips applied on the hoof. 

MATERIALS AND METHODS

The measurements of hoof were carried out on 46 adult dairy cows of the institutional dairy farm located at Bengaluru and Shivamogga. The age of the animals was determined by the dental formula. The following linear measurements (Fig 1) were taken in centimeter (cm) using a flexible measuring tape as previously described by Scott et al., (1999). Accordingly, the measurements taken were; coronary band (the distance around the proximal border of the coronary band from the abaxial groove to flexure of the dorsal surface), base (the distance from the abaxial groove, along the distal border or weight-bearing region of the hoof to the point of the toe), abaxial groove (the height of the abaxial groove from the proximal border of the coronary band to the base of the hoof) and toe (the length of the toe from the proximal border of the coronary band to the point of the toe).
 

Fig 1: Schematic diagram showing the linear parameters measured for calculation of volume of hoof in this study


       
For assessment of hoof volume, three measurements (coronary band, base and abaxial) were taken from medial (left and right) and lateral (left and right) claws of forelimb and hind limb in centimeters. The measurements of lateral and medial claws of the same hoof were added and the values were put in the following formula (Scott et al., 1999): style="text-align: center;"> 
Claw volume (cm3) = (17.192 x Base) + (7.467 AbaxGr) + 45.270 x (CorBand) -798.5
 
For the measurement of the thickness of the hoof capsule, the hoof samples of dairy animals were collected from post mortem cases from animals which had died not due to hoof lesions. Samples were brought to the laboratory and washed and cut mid-sagitally and were measured for the thickness of hoof capsule (mm) using caliper at different points on the wall (a, b, c) and on solar surface (d, e and f) as shown in the  Fig 2.
 

Fig 2: Schematic view of the measurement points (a, b, c) and (d, e, and f) on the wall on solar surface) in the dairy animal hoof determined macroscopically


 
Evaluation of a lameness scoring system for dairy animals
 
The evaluation for the cow for lameness was done before and after the application of Cowslips onto the animals. Locomotion Score is a qualitative index of a cows’ ability to walk normally. Visually scored on a scale of 1 to 5 (Table 1), where a score of 1 reflects a cow that walks normally and a score of 5 reflects a cow that is three-legged lame, an LS is visually assessed in only a few seconds per cow.
 

Table 1: Locomotion Scoring Guide.


       
A 5-point lameness scoring system was developed based on previously published systems but optimized for use under field conditions. The scoring system included the words “in most cases” in the descriptions of the clinical signs evaluated. This was done to avoid a situation in which cows might not fit into any of the categories. Additionally, a number of clinical signs used in other lameness scoring systems, considered of less importance in relation to lameness, were not included. Only clinical signs were included that could easily be assessed within a few seconds from a distance (Thomsen et al., 2008).
       
Anatomical terms were used in agreement with the Nomina Anatomica Veterinaria (NAV, 2005). The photographs of hoof samples were taken using a digital camera (Nikon®, MH 611 COOLPIX P5100, Japan).
 
Histology of the of hoof capsule
 
To study the microscopic structure of the hoof capsule, a tissue of 5-10 mm thickness was collected from the hooves of six crossbred cows (blue rectangle in Fig 3), fixed in 10% neutral buffer formalin and processed for routine histological technique with some modifications. As some samples contained keratin, we used harsh hydration process, which consisted of treatment with 10% HCl for 15-30 min and then put it on ice. The tissue pieces were routinely processed and embedded in paraffin wax (Luna, 1968). Then, the samples were sectioned using semi-automatic microtome (Leica® RM2245, Leica Biosystems Pvt. Ltd., Singapore) to make 5-7 µm thickness sections, the sections were carried on glass slides which were smeared with a swab of Mayer’s egg albumin and then placed on the hot plate for 24 hours for the purpose of drying. The slides were stained using routine H and E staining technique (Singh and Sulochana, 1996). The photographs were taken with a Nikon digital camera (Nikon®, MH 611 COOLPIX P5100, Japan) attached to CH 20i Olympus trinocular microscope. For image analysis, slides were viewed in a microscope (Olympus CX 41) equipped with a Q-imaging Micro publisher 3.3 RTV. The image was reflected onto the screen of a Q-Capture Pro 7 for measurements.
 

Fig 3: Sagittal section of a animal hoof demonstrating proximal (P I), middle (P II), distal phalanges (P III), the distal sesamoid (DS), surrounding soft tissues digital cushion (DC) and Dermo-Epidermal Junction of the sole, wall and bulbar region.


 

Fig 4: Photomicrograph of the hoof capsule/epidermis in bovine showing


 
Designing and development of rubberized cowslips
 
Based on the literature survey and considering the physical properties of the available materials and their usefulness in the preparation of Cowslips, rubber material was selected to prepare Cowslips. The designing of rubberized Cowslips was carried out manually as per the cobbler’s procedure based on morphometric data obtained in the present study in the laboratory of MyPol, Pvt Ltd, Mysore (Fig 5).
 

Fig 5: Graphical representation of design and development and application of rubberized Cowslips.


       
The rubberized Cowslips were prepared manually using the above hoof cast prepared in the laboratory of MyPol Pvt Ltd., Mysore. The waste tyres were collected from automobiles shops and they were cut to the required sizes and shape. The size and shape of Cowslips were optimized for perfect design and prepared at three different sizes viz., small, medium and large. Initially blueprint for hoof was designed, followed by the blueprint for hoof and then card/drawing sheet template and then the negative molds (hoof cast) for the different sizes of hoof were prepared using thermostable materials. Below this mold, the lower hard part of Cowslips was designed using 0.5 to 1cm thick pieces of rubber wastes. Over the mold, the upper soft part of Cowslip comprised of nylon cloth which was glued to the lower part to get perfect shape and size of Cowslips. Finally, the whole set up along with mold was vulcanized as per standard process to get durable Cowslips (Fig 5).
 
Application of the cowslips to the hoof of animals
 
A randomized trial on the application of Cowslips was conducted at Institutional farm located at the veterinary college campus, Shivamogga, Karnataka, India. The claw of the hoof on which the Cowslip is to be applied was selected.  It was ensured that there were no lesions on the claw on which Cowslip was to be applied.   
       
To ensure proper adhesion of the Cowslip, it is essential that the claw of the hoof should be prepared. Then the conditioner (comprising a mild acid, ferric chloride) was applied to the selected claw of hoof for a time sufficient to etch and further expose the epidermis layer of the hoof until stratum externa approximately 1-2 mm depth (Lustgarten, 2007). The claw was dried thoroughly with a paper towel and wiped with spirit to degrease it. Then, the Cowslip was tested to make sure that it fitted to claw. Cyanoacrylate based instant adhesive (Anabond® 202) was applied to the interior of the Cowslip profusely. The Cowslip was applied to the claw applying gentle pressure on the wall of the hoof and the excess adhesive was cleaned. Leave the foot off the ground until the glue is dry. Then the cow was allowed to still stand for a few minutes (Fig 5). Finally, the observations were recorded to evaluate the retention period of the Cowslips as shown in Table 2. For comparison, Demotec® (UK, Distribution, Centre, Shropshire) Cowslips imported were also applied on to hoof of normal animals (n=8) as per manufacturer’s instructions and the retention period was recorded.
 

Table 2: The linear measurements of hoof of dairy animals.



Additionally, to study the effect of urine on adhesiveness of the cyanoacrylates between hoof and rubberized Cowslips, the Cowslips were applied onto the hooves of animals collected from post-mortem samples using cyanoacrylates based instant adhesive (Anabond®, 202) and then kept them in jar containing undiluted cow urine and tap water for 30 days to observe for the bondability of adhesives in the urine by checking the firmness of attachment subjectively.
 
Statistical analysis
 
The statistical analyses of various biometrical parameters of hoof were depicted in a tabular form (Table 2). Data were presented as Mean ± SEM. The nomenclature used was referred to according to the International Committee on Veterinary Gross Anatomical Nomenclature (2005).

RESULTS AND DISCUSSION

Current methods of providing non-medicated relief to pain arising out of hoof lesions are the either traditional way of metallic nail-shoeing or the application of nail-free shoes (Cowslips) which have been developed recently. Shoeing by nailing into the hard outer horn tissue of the hoof is an age-old and most popular method. However, nailing may weaken the hard horn, create various micro-cracks and loosening. This exposes hoof to a variety of adverse conditions and may support various fungal and bacterial maladies (Lustgarten, 2007). Further, metal shoes do not have any impact on absorption and stress distribution.
       
A variety of wear-resistant plastic shoes have recently been designed and developed to cushion these high impact forces and for better distribution them within the hoof when meeting the ground. However, the plastic shoes available in the market are very expensive and hence not affordable by small and medium dairy farmers. Therefore, we could think of an alternative appropriate material that is easily available and economically viable such as rubber-wastes for the preparation of Cowslips in the present study.
 
Morphometry of hoof
 
The hoof of dairy animals consisted of hoof capsule (epidermis), hoof corium (dermis and hypodermis) and phalanx. Distal phalanx and about half of the middle phalanx are covered by a hoof capsule. Anatomical features of the forelimb resembled those of hind limb, including hoof periphery, hoof coronal, hoof wall, hoof sole and cushion (Fig 3).
       
The average thickness of the horn capsule (epidermis) of the wall and solar region of the hoof was 0.61±0.3 cm and 0.52±0.1 respectively.  Browne et al., (2007) evaluated beef bulls and dairy heifers 20 months old and reported values lower than ours. In general, capsule thickness varies greatly in the sole. The soles were designated as ‘thin’ if the sole horn thickness was more than 5 mm (Shakespeare, 2009). The Morphometrical was data essential for the designing of the template for the Cowslip were recorded (Table 2).
 
Histology of the claw capsule of hoof
 
In the present study, the hoof capsule of dairy animals consisted of epidermis, dermis and hypodermis or subcutis. The coronary regenerative layer of the dermis continuously gives rise to new epidermis layers, which include the outer horn or external stratum (dead horny tubules), medium stratum and stratum internum or stratum laminae. The modified epidermis of the claw horn capsule is a multilayered structure of cornified epithelium that overlies the corium (Fig 3 and 4).  The primary structural protein of the epidermis is keratin. In the claw horn, the keratins in greatest abundance are “hard” keratins (i.e., those with a greater amount of disulfide bonding). In contrast, the skin contains more “soft” keratins which contain a greater amount of sulfhydryl bonds and this is consistent with Pollitt (1996).
 
Designing of rubberized cowslips
 
The traditionally used conventional nailed shoes for animals needs a skilled person for its application and may cause injury due to improper shoeing. This can be overcome by developing nail-free shoes (Cowslips) which could be applied by the dairy farmer himself easily and quickly without the need for farriers. However, the Cowslips presently available in the market are imported and are expensive as the cost of PVC based Cowslips was approximately Rs 1000/- per pair (Table 3).
 

Table 3: Comparison of retention period of rubber based Cowslips applied on to the randomly selected animals (n=8) with that of PVC based Demotec® Cowslips (n=8).


       
The selection of the materials and adhesives for the preparation of Cowslips was made considering the criteria which render them most suitable for the study. The durability, glueability, impact/ wear resistance and economic viability were the criteria considered for Cowslip materials whereas; good bondablity, instantaneous curability and weather-resistance were considered for adhesives. Based on the literature survey, considering the physical properties of the available materials and their usefulness in the preparation of Cowslips, rubber material was selected to prepare Cowslips. This also makes the product cheaper and eco-friendly.
       
Preparation of the hoof claw was done as per the procedure described earlier (Lustgarten, 2007) with little modification in the type of adhesive used. Here, we used ready-to-use cyanoacrylate-based adhesives (Anabond® 202) instead of poly (methyl methacrylate).
       
After the conventional trimming, a mild acid conditioner was applied to the hoof to etch and further expose the inner epidermis layer of the hoof, which comprises hollow tubules and a network of fibrous keratinized intertubular and peritubular horn tissue and this further strengthened the mechanical bonding conferred by the adhesive between the rubber Cowslip and the horn capsule when applied.
 
Evaluation of retention period of cowslips
 
In the present study, we have designed rubberized Cowslips (nail-free shoes) which are to be glued onto the hoof. Rubber belongs to the class of materials referred called an elastomer. The main characteristic of rubber is its property of high elasticity which allows it to undergo large deformations from which almost complete, instantaneous recovery is achieved when the load is removed (Beaty, 1992). This property of high elasticity qualifies it to be a better material for the preparation of Cowslips. The rubber-based Cowslips prepared in the present study were compared with the imported Cowslips available commercially concerning their retention period, change in gait/behavior, change in the milk yield and cost of production (Table 3).
       
comparable to that of the commercial Cowslips. There was no change observed in the behavior of the animals while walking and also no change in the milk yields between the two groups in the present trials. But the rubberized Cowslips were far cheaper than that of commercially available ones as they were prepared indigenously using locally available rubber tyre waste materials. However, further research, to enhance the retention period of the rubberized Cowslips by using improvised glues to increase interfacial adhesions (bondability) between rubber material of the Cowslip and keratin protein of the hoof, needs to be carried out.

CONCLUSION

The Cowslips were developed indigenously using rubber tyre wastes based on the morphometric data of hoof and application of Cowslips as a promising tool for the prevention of lameness in bovines. Preparation of Cowslips using rubber tyre waste along with cyanoacrylates found to be economically viable. It also promotes making good use of wastes. As rubber is an elastomer and more durable, the use of rubberized Cowslips is the most appropriate method of elevating an affected claw of the hoof in conditions of lameness that is likely to respond to removal of weight-bearing forces. The cost of a rubberized Cowslip was approximately one-twentieth of a commercial hoof block kit, which will make it more acceptable in field conditions. However, there is a lot of scope for enhancing the retention period of the rubberized Cowslips by using improvised glues to increase interfacial adhesions (bondability) between rubber material of the Cowslip and keratin protein of the hoof.

ACKNOWLEDGEMENT

The first author is thankful to Karnataka Veterinary, Animal and Fisheries Sciences University, Bidar for the financial support extended to carry out the research work from which the manuscript is derived.

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