Comparative study on the relations between backfat thickness in late-pregnant gilts, mammary development and piglet growth

The potential relation between body condition of gilts in late-pregnancy and litter BW gain as well as mammary development was studied using 2 sets of data. Gilts either from a commercial herd (Part 1, n = 182) or from a series of trials looking at mammary development (Part 2, n = 172) were separated in 3 groups according to backfat thickness (BF) on d 110 of gestation. Group categorization was similar for Parts 1 and 2 of the study and was: low (LOW), 13.6 ± 1.6 mm (mean ± SD); medium (MED), 17.6 ± 1.0 mm (mean ± SD); and high BF (HIGH), 21.8 ± 1.8 mm (mean ± SD) for Part 1, and LOW, 14.2 ± 1.3 mm (mean ± SD); MED, 18.1 ± 1.0 mm (mean ± SD), and HIGH 23.4 ± 2.6 mm (mean ± SD) for Part 2. The effects of BF group on piglet BW gain (Part 1) or on various mammary gland characteristics (Part 2) were determined using ANOVA. Litters from HIGH sows tended to have a greater lactation BW gain than those from LOW sows (P < 0.10). Sows with HIGH BF had more mammary parenchymal tissue and more total protein and total DNA than MED and LOW sows (P < 0.05), which led to greater total protein and total DNA contents (P < 0.05). There were strong positive correlations (P < 0.0001) between parenchymal weight and total protein, total DNA, and total RNA. Results suggest that it is beneficial for primiparous sows to have greater BF (i.e., 20 to 26 mm) at the end of gestation to achieve optimal mammary development and greater litter BW gain in the subsequent lactation.