Healthy claws: Key for overall sow health

Over 84% of the sows suffer from one or more claw lesions¹, while 10-15% of the western European sows suffer from lameness². Group housing of sows can have a negative influence on claw health. Since 2013, group housing of gestating sows is mandatory in the EU, and the incidence of claw problems has increased³. Lameness decreases fertility and performance and it increases culling rates and the economic consequences are estimated at losses of € 37-€ 138/sow. Sows with claw problems will give birth to fewer litters before culling (3 vs. 4.5) and the litters are smaller with fewer live born piglets.

Since the investment in a sow is paid off after 3-4 litters, paying attention to claw health and preventing lameness is important to improve longevity of sows and economic profit to the farmers. Beside housing management, nutritional tools can be used to improve claw health of the sow herd. Trace minerals copper and zinc are known for their positive influence on skin health, wound healing, strength and elasticity of the sole, heel and wall horn⁴. Selenium improves immunity and fertility in general by its antioxidant capacity⁵. By using new generation trace mineral sources with a high bioavailability, the mode of action of these trace minerals in the metabolism of the animals is ensured and claw health can be improved. This hypothesis was tested on a practical farm in the Netherlands.

Source of the trace minerals

Copper and zinc are important for wound healing, skin epithelia regeneration, wall horn strength, elasticity and keratin synthesis⁶. These mechanisms are important for healthy skin, cartilage and claws. Copper and zinc also contribute to mineral deposition in bones, ensuring bone strength⁷. Selenium is present in at least 25 selenoproteins and is thereby important for maintenance of a good functioning immune system because of its antioxidant and anti-inflammatory capacity⁸.

In order to ensure the mechanisms of copper, zinc and selenium, it is important to use the best available sources. Hydroxy copper and zinc are covalently bound, this bond is stronger than an ionic sulphate bond, therefore ensuring stability in the feed and non-solubility in water environments. They slowly release their mineral element in the gastro intestinal tract at the place of absorption, ensuring high bioavailability and therefore increasing their efficacy in the physiology of the animal. Selenomethionine is utilised by the body as an amino acid and is built into animal protein tissue. Organic selenium in the form of L-selenomethionine is able to build up selenium reserves in the body, which ensures a good selenium and antioxidant status at all times. While selenium yeasts contain only a part of the selenium in form of selenomethionine, all the selenium in the new generation of organic selenium (Excential Selenium4000, hereafter called organic selenium) is in form of L-selenomethionine, therefore ensuring high efficacy and increased benefits of its mode of action.

The effect in practice

To show the effect of the higher bioavailable copper, zinc and selenium sources, a claw health trial was performed on a practical farm with 775 sows. In the 1.5% premix, 15 ppm copper sulphate (CuSO4) was replaced by 15 ppm hydroxy copper (dicopper chloride trihydroxide). 75 ppm zinc sulphate (ZnSO4) and 40 ppm zinc chelate were replaced by 80 ppm hydroxy zinc (zinc chloride hydroxide monohydrate). 0.2 ppm selenium yeast (Se-yeast) was replaced by 0.2 ppm ‘organic selenium’. The premix composition is stated in Table 1. The premix was dosed at 1.4% in gestation feed and at 1.6% in lactation feed. The rest of the premix and compound feed was not changed during the trial. By using the score sheet developed by Wageningen University, the claws of all sows in the lactation room were scored monthly.

After two zero measurements, in which the sows received their former diets, the source of copper, zinc and selenium in the premix were changed for the higher bioavailable sources (Table 1). After premix replacement, monthly scores were continued for one year. The score card uses five areas on the claw: cracks and overgrowth of the ball area; length of the dew claw; length of the inner- and outer claw; cracks in the wall horn and skin lesions. Score 1 – 4 are given according to severity of deviation from “normal”, 1 being normal, 4 being extremely abnormal (e.g. very long toes or severe cracks in the wall horn; see image of the scorecard for further detail). When comparing the zero measurements to the average of the industry in the Netherlands, it became apparent that wall horn cracks and skin lesions caused the largest problems on this particular farm. As mentioned before, zinc, copper and selenium can have a positive effect on skin health, wound healing and general immunity, therefore it could be expected that the scores in these areas would improve by the higher bioavailable trace mineral sources.

Figure 1 – Distribution (%) of scores for cracks and overgrowth of the ball area.

Figure 2 – Distribution (%) of scores for cracks in horn wall.

In Figure 1 to 3, the results of the scores for ball area, wall horn and skin lesions are shown. By using colours the four scores are shown in % over time (colour – score combination shown in legend). It can be seen that wall horn, skin lesions and ball area are improved by the treatment in this trial and are stable over time. The amount of sows with score 1 is increased at the expense of the amount of sows with score 3 and 4. Average scores 3 and 4 for wall horn was 4.9% and this decreased to 2.0% during the trial. The average scores 3 and 4 of 5.3% for skin lesions before the trial was improved to 1.4% during the trial. For the ball area, 4.3% of the sows had score 3 and 4 before the trial versus 1.5% during the trial. Lengths of the (dew-) claws were already very good, so they could not be improved a lot. Scores of 3 and 4 for length of dew claw was 0.3% before trial and 0.9% during the trial and scores 3 and 4 for length of inner- and outer claw was 1.8% before trial vs. 2.0% during the trial. Figure 4 shows the number of individual sows with a decrease in score and those that had improved scores over the course of the trial. It can be seen that the amount of sows with improved scores was larger than the amount of sows with worsened scores, especially for ball area, wall horn and skin lesions.

Figure 3 – Distribution (%) of scores for skin damage above the claw.

Figure 4 – Number of sows with an improved and worsened score.

Conclusion

Claw problems are important issues in pig husbandry and when they can be prevented or cured, fertility and performance of sows can improve and culling rates can be reduced. The use of the new generation high bioavailable zinc, copper and selenium sources can be a suitable tool to improve claw health, which has been shown in the practical trial described here.

References 1-8 available on request from the author (eising@orffa.com).

Author: Irene Eising, International Technical Manager, Orffa, The Netherlands