sole junction, separations and cracks along the white line, horizontal and vertical wall cracks, skin lesions near the claw and excessive dew claw length. One of the primary causes of claw lesion is insufficient supply of proteins and amino acids, fatty acids, minerals and vita- mins, which affects claw horn quality and integrity and thus increases claw susceptibility to chemical, physical or micro bial damage from the environment. Required nutrients for claw horn quality and integrity are described in the next section.


Nutrients for claw horn quality Proteins and amino acids Claw horn quality and integrity may be impaired during late gestation and lactation, due to higher amino acid require- ments in sows during this period. Sows may not be able to generate enough proteins to meet this increased demand, especially when dry matter intake is decreased during early lactation. Insufficient protein production interferes with claw horn production, impairs claw horn quality and integrity and increases risk of claw lesion and lameness.


Fatty acids There is an association between dietary fatty acid content, the fat layer of the claw and claw resistance to environmental challenges. The sows fed a low-fat feed ration may have lower claw horn quality and integrity and increased risk of claw lesion and lameness.


Minerals Minerals are important for claw horn production, and they improve claw horn quality and integrity. The demand for minerals increases during late gestation and early lactation. Insufficient dietary mineral availability or an interrupted dif- fuse supply results in inferior claw horn integrity and may increase the risk of sow lameness. Calcium influences claw horn production through the initia- tion and regulation of keratinisation and cornification. Zinc is a key mineral in the keratinisation process, and it improves sow claw horn quality and integrity. Copper provides structural strength and rigidity to the kera- tinised cell matrix, making it more resistant to mechanical and physical forces. Manganese has an instrumental function in the keratinisa- tion process, and it plays an important role in maintaining claw horn quality and integrity. Additionally, adequate zinc, copper and magnesium supple- mentation for claw keratinisation makes the skin and the un- derneath sensitive tissue less susceptible to separation or breakdown and ultimately improves epithelial integrity of claws. The main role of selenium is to protect the intercellular cementing substance. Low dietary selenium concentration creates inferior claw horn with poor rigidity. Chromium is a cofactor in insulin activation, and it has an indirect effect on inferior claw horn production, which may result in claw lesions and lameness. Molybdenum is necessary for metabolism of sulphur-con- taining amino acids, which affect claw horn quality and integrity.


Vitamins Vitamins have a supportive role in claw horn quality and integrity. Vitamin A is required for cell differentiation, and its deficien- cy results in poor claw horn growth and calcification. Vitamin C is important for collagen synthesis occurring in the claw horn. Biotin is necessary in the keratinisation process, and it improves claw horn strength, integrity and hardness and reduces the number of claw lesions. Insufficient vitamin E decreases cellular energy production and increases occurrence of claw lesions.


Nutrition as predisposing factor Nutrition – including dietary composition, intake and availabili- ty of the nutrients ingested – is an important predisposing fac- tor of sow lameness. Insufficient supply of proteins and amino acids, fatty acids, minerals and vitamins may be detrimental to claw horn quality and integrity. Furthermore, an optimal dietary supply of proteins and amino acids, fatty acids, minerals and vi- tamins with adjustment in gestation and lactation periods is essential to prevent claw lesions and lameness in sows.


▶ PIG PROGRESS | Volume 37, No. 10, 2021 35


PHOTO: BERT JANSEN


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