Long-term impact of zinc supplementation in sows : impact on claw quality

Objectives: To evaluate the long-term impact of zinc (Zn) supplementation on claw lesions, claw conformation, and histological and mechanical claw characteristics of sows housed in groups on rubber top layer or concrete floors during gestation. Materials and methods: Six groups of 21 +/- 4 sows were allotted to group housing on different floor types for 80 days during gestation. Within each group, sows were randomly allocated to one of three diets supplementing a basal diet (46.6 and 128.9 mgZn per kg during gestation and lactation, respectively) with 0, 50, or 100 mg Zn per kg. Claw lesion scoring, claw conformation, and horn growth and wear measurements were performed at days 50 and 140 of every cycle. Histological and mechanical characteristics were evaluated on claw samples of 36 sows after slaughter. Results: Dietary Zn supplementation affected heel horn erosion score (P = .01): sows supplemented with 100 mg Zn per kg diet had better scores. Distances between dermal papillae of the sagittal heel horn were larger (P = .004). Heel height was lower for sows supplemented with 0 and 100 mg Zn per kg than for 50 mg per kg (P = .01). Horn growth and wear were lower for sows housed on rubber at day 50 (P< .001, both variables), but not at day 140. Dermal papillae distance was shorter for sows on rubber (P = .04). Implications: Unlike floor type and phase within the reproductive cycle, and under the conditions of this study, dietary zinc supplementation minimally influences claw quality