Lameness and hoof quality issues are becoming an increasingly common problem on a greater number of swine farms, leading to more culling of sows. Health problems associated with limb injuries are most common in bedding-free systems where uneven, wet and slippery floors increase the risk of both limb injuries and infections. Based on the available literature, limb weakness, lameness, paresis, inability to walk, and hoof injuries account for approximately 8-16% of all culling. Reproduction disorders (20-30%), sow age (18-40%) and poor production (2-12%) account for the other major reasons for culling (Figure 1). However, alongside the trend towards greater intensification of production, problems linked to lameness are becoming more common.
Lameness reflects pain of an injury (Figure 2). For example, incorrect slat widths in slatted floors can cause inflammation if hooves get stuck between them, resulting in abrasions or injuries. Analysis of hoof and limb condition in the sow herd, and the level of sow culling due to hoof and limb issues, provides us with important feedback on the correct husbandry and management of a herd, which directly impacts production efficiency.
Carrying the weight
The hoof horn is a cutaneous appendix that serves as a barrier protecting the internal structures of the phalanges, and secures the hardness and flexibility of the hoof. Sows must support their entire body weight on the relatively small surface of the horn sole. Maintaining limbs and hooves in the best possible condition is crucial to limiting production losses.
In bedded floor systems, problems arise from excessive hoof horn growth due to insufficient wearing of the horn layer. Over-grown hooves alter limb positioning and shift the animal’s weight from the sole surface to the soft heel at the back of the hoof. This leads to heel injuries, often with subsequent inflammatory conditions.
The hoof horn should be hard whereas the sole should be flexible. On bedded floors, attention should be paid to bedding moisture; if the surface is too wet, the hoof may undergo malacia. The hoof will harden when the animal is moved onto a dry surface, however the hoof then loses its previous elasticity, and cracks and fissures may develop, predisposing the animal to further infections.
Diet is the key
As the last point in Figure 4 suggests, a well-formulated, balanced ration matched to the maintenance requirements of sows, and containing all the essential nutrients, vitamins, minerals and trace elements, is a key factor in determining the correct growth and function of limbs and hooves. Trace minerals (e.g. copper, iron, manganese, zinc, molybdenum, chromium, fluorine, silicon and selenium) require special attention as they play a crucial role in the proper functioning of the body; they are closely associated with hoof horn development, ossification and proper limb development.
Seven basic rules help to maintain hooves and limbs in good health
- Maintain and control floor quality in pens
Remove sharp edges (or file sharp edges when necessary)
Ensure the correct slat width in slatted floors
Keep the floors non-slippery by providing dry and clean resting areas
- Minimize social and hierarchy clashes
Introduce husbandry solutions that will prevent hierarchy clashes
Provide sufficient pen space and free space per number of animals
- Integrate gilts ready for reproduction
- Follow correct cleaning and disinfection procedures
- Set up hospital pens for diseased sows
Clean and disinfect areas where sick sows are kept, disinfect wounds
Bathe hooves in copper sulphate solution
- Do proper hoof trimming
- Adjust the nutrition for physiological requirements of sows;
when needed, additional supplementation may be introduced
Pitfalls with trace elements
A deficit or an excess of trace elements can negatively impact sows. Copper is a part of many enzymes, as is manganese, but it also has an impact on the reproductive process and supports bone development. Excess copper may impair the function of the liver and muscles, causing symptoms including reduced growth rate, poor hair condition and neurological disorders reflecting the intoxication state. Zinc also plays a significant role in the ossification and healthy growth of the hoof horn. Zinc deficiency presents with excessive fragility of the horn, visible colour changes and skin keratinization, while overdosing results in reduced appetite and arthritis. These examples highlight the importance of providing the correct amounts of trace minerals required by each production group.
Getting the balance right
While formulating and balancing the rations, the antagonistic effects between the trace elements should be considered, e.g. between iron and manganese or between iron, copper and zinc. A reduction of iron and manganese levels should be accompanied by a decreased dose of copper and zinc as the requirements of the animals dictate. The goal is to deliver optimal amounts of required trace elements in the most accessible form without putting any excessive pressure on the body. Numerous data indicates that chelates, which are the organic forms of trace minerals, are the most bioavailable. By administering chelates, the animal can ingest the amount needed of a given compound while eliminating any excess together with an inactive part of the chelate. The use of organic forms of trace elements in sow nutrition results in a significant increase in production parameters as well as a visible improvement in hoof and limb quality. It is thus worth considering the introduction of additional supplements containing specific chelate compounds into the sow ration. Such products are administered as top dressings, namely in addition to a regularly fed diet.
However it should be considered that vitamin-mineral additives, commonly used in feed mixtures, should provide the animals with all necessary elements in a basal ration; the decision to introduce additional supplementation should be taken in justified cases to solve any already existing problems. Specialized products with desired elements are administered for a specific period, e.g. three to four months, and not on a continuous base. By observing the basic rules of welfare, hygiene, husbandry and management of the herd, in many cases it is possible to avoid the additional costs associated with problems resulting from limb or hoof injuries. Some predisposing factors can be eliminated in advance which then helps to achieve better performance and protect the producer against potential losses further on in the production cycle.