Associations between sow body lesions with body condition and reproductive performance

Abstract Text: The objective of this study was to determine the association between vulva and shoulder lesions with body condition and reproductive performance for sows housed in gestation pens. Whiteline sows (n=887) were measured before farrowing and at breeding for the next reproductive cycle in a commercial farm in eastern North Carolina. Following weaning, sows were housed in gestation stalls for 40 d, and then allocated to pens of 4 to 5 sows (1.49 or 1.86 m² per sow, respectively). Vulva lesions were scored 0 (no lesion) or 1 (lesion present). Shoulder lesions were scored 0 (no lesion), 1 (abrasion) or 2 (open). Sow body condition measures included: a Knauer sow caliper (CS), weight (WT), body condition score (BCS), backfat (BF) and longissimus muscle area (LMA). Backfat and LMA were measured from a 10th rib cross-sectional image by a Real-Time ultrasound technician. Visual BCS was scored on a 1 to 5 scale by an experienced technician. Sow production traits included: number born alive, litter birth weight, number weaned, litter weaning weight, piglet survival (number weaned ÷ (total number born + net transfer)) and wean-to-conception interval. Data were analyzed in SAS using PROC GLM for continuous traits and PROC GLIMMIX for categorical traits. Vulva lesions were recorded on 17.6% of sows at farrowing and 0% of sows at breeding. No shoulder lesions, abrasions and open wounds were recorded on 100, 0 and 0%, respectively, of sows at farrowing and 73, 21 and 6% of sows at breeding, respectively. The incidence of vulva lesions at farrowing was associated (P<0.05) with a lower CS, WT, BCS, BF and LMA at farrowing, reduced (P<0.05) piglet survival (4.3%) and a lower (P<0.05) BCS at breeding. Sows with a lower CS at farrowing had a greater (P<0.05) incidence of shoulder abrasions and open lesions at breeding.  Backfat at farrowing had a curvilinear association (P<0.05) with open shoulder lesions at breeding with a BF of ≥3.3cm minimizing open lesions. Body condition score at farrowing had a curvilinear relationship (P<0.05) with shoulder abrasions at breeding with a BCS of ≥3.9 minimizing abrasions. As WT and LMA at breeding decreased the occurrence of abrasions tended to increase (P<0.10) and open shoulder lesions increased (P<0.05). Results showed vulva and shoulder lesions were generally associated with thinner sows but had little impact on reproductive performance. Although statistically significant, body condition measures explained little variation in lesion scores (r²≤0.05). 

Keywords: lesion, reproduction, sow