Part 4 - Factors to consider for gilt development that may reduce lameness and improve productivity

In this series of articles, we have been discussing some critical factors that swine producers and nutritionists must consider when managing sows, in order to support them to wean healthy and viable pigs. Now, it’s time to bring another hot topic to that discussion: lameness and its impact on sow herds.

As we know, lameness is a common clinical manifestation in the swine industry worldwide, with multifactorial causes that impact an animal’s welfare, reduce productivity, promote premature culling, and, subsequently, cause significant economic losses (Lucia et al., 2000). Lameness can have infectious and non-infectious causes. Among the non-infectious causes are several risk factors closely related to gilt development that contribute to lameness, such as flooring types, housing conditions, congenital disorders, seasonal influence, nutritional imbalance, feed management, and genetic predispositions (Mondal & Biswas, 2021). However, when these risk factors are properly evaluated, the farm can reduce lameness, extend the reproductive life of gilts, and thereby improve pork production.

Now, let’s dive into the nutritional aspects. The diet’s composition is an important aspect to be considered when planning to supply the minerals and vitamins that are necessary to avoid limb abnormalities and, consequently, lameness. Copper, zinc, and manganese are trace minerals that are important for proper bone development (Beattie & Avenell, 1992; Dibner et al., 2007). When supplied in complexes or chelates with an organic ligand instead of inorganic trace mineral salts, they become more bioavailable and bioactive (López-Alonso, 2012; Miles & Henry, Peter, 2000). These trace minerals are essential for both pregnant and non-pregnant sows for a variety of reasons, including reducing lameness (Nair, 2011; van Riet et al., 2013), improving locomotion scores (Quinn et al., 2015), and increasing bone mineral density (Hartnett et al., 2019; Quinn et al., 2015). In addition to the supplementation of trace minerals, rearing gilts in female-only groups helps to reduce the number of joint lesions, improving limb health and longevity of sows (Hartnett et al., 2019).

The diet composition and feeding strategy are important considerations that affect the growth and development of gilts intended for breeding. For improving the limb health of gilts, there is increasing evidence that strategies to optimize growth and development (rather than maximize growth rate) can reduce the incidence of osteochondrosis and, consequently, lameness. Ad libitum diets and dietary restrictions may also influence limb health which, depending on the age of the pig, can lead to osteochondrosis or possible lameness. Osteochondrosis is a disturbance in the ossification process of growing pigs, especially those between 7 and 13 weeks of age (Ytrehus et al., 2004a, b, Ytrehus et al., 2007). De Koning et al. (2013) demonstrated that dietary restriction (80% of ad libitum uptake) has an age-dependent effect on osteochondrosis development in gilts. When fed with dietary restriction until 10 weeks of age followed by ad libitum feeding, gilts had the highest prevalence of osteochondrosis. On the other hand, gilts continuously fed in a restricted manner or only experiencing restricted feeding after 10 weeks of age can have a reduced prevalence of osteochondrosis (de Koning et al., 2013). In many instances, developing gilts are housed in groups with feeding systems that are designed for ad libitum feeding. With an ad libitum feeding system for gilts in groups after 10 weeks of age, it can be beneficial to feed a high-fiber diet that is lower in energy. Feeding a balanced, high-fiber/low-energy diet to replacement gilts ad libitum may slow growth for improved development, while increasing satiety and reducing competition and variability in feed intake; thus, providing benefits for both welfare and sow longevity (Belkova and Rozkot, 2022).

Another strategy to prevent osteochondrosis and consequent lameness is to strengthen bone and cartilage from the nursery phase to the finishing phase (Wardale & Duance, 1994). 25-hydroxy-cholecalciferol is one of the metabolites of vitamin D3, known to help maintain calcium plasma concentration, promote cartilage and bone metabolism, and reduce tibial dyschondroplasia in growing broiler chickens – which presents similar lesions to those seen in pigs with osteochondrosis (Fritts & Waldroup, 2003; Ledwaba & Roberson, 2003). Upon supplementing 50 μg/kg or 100 μg/kg of 25-hydroxy-cholecalciferol for 42 days to 60-day-old gilts with an average initial body weight of 23.13 ± 1.39 kg, the expression of calcium and phosphorous transporter genes was improved without affecting skeletal integrity and growth performance (Regassa et al., 2013). Also, Brana et al. (2012) observed that supplementation of 56-day-old crossbred growing gilts with 50 μg/kg of 25-hydroxy-cholecalciferol until selection improved bone development and structural soundness.

Besides nutritional effects, many other factors are involved in lameness, which leads to reproductive failure, premature culling, and a shortened lifespan. The method of feeding, the group and space size, as well as the type of housing all serve to influence the animal’s behavior – which can lead to stress, trauma, and lameness (Hallowell & Pierdon, 2022). Moreover, sows with lameness generate fewer total litters in their lifetime, produce a greater proportion of piglets with low birth weight, have a higher piglet mortality rate, and wean fewer piglets per litter. These outcomes are likely due to the pain and stress caused by lameness, that may subsequently impair ovulation, estrus behavior and maternal care (Einarsson et al., 2008; Hallowell & Pierdon, 2022). Also, since there is convincing evidence that litter-of-origin variables are associated with the development of reproductive functions and lifetime productivity, strategies must be implemented to improve birthweight and decrease intra-litter variation (Flowers, 2022).

Therefore, understanding the link between lameness and its multifactorial causes can help producers make better decisions regarding the best housing, the animal’s genetics line, nutritional and management strategies to minimize its occurrence and increase the longevity and productivity of the swine herd.