Sow Backfat Thickness Changes during Lactation, their Total born and Weaning Performance: Implications of Sow Parity Number

This study aimed to assess the backfat thickness (BFT) of sows and its relationship with weaning performance in one sow farm in Eastern Hungary.A total of 196 sows of different parities (P) 1-7 were investigated.Variables analyzed included BFT D109 of gestation, total born (liveborn LB, stillborn SB and mummies M), BFT D28 (at weaning), and number of piglets weaned (NwP).Test for normality was performed using One-Sample Kolmogorov-Smirnov (KS) test.Data were analyzed using Kruskal-Wallis (KW) H-test to determine if there were significant differences across parities followed by Post-hoc pairwise multiple comparisons where significance was detected.Spearman's correlation was used to assess the relationship between BFT D28 and NwP.With a degree of freedom of 6, the results showed that parity significantly differed for BFT D109 (KW=24.114,P<0.001) and for NwP (KW=42.843,P<0.001).There were no parity differences in the LB, SB, M and BFT D28 (KW=8.642, P=0.195, KW=10.137,P=0.119, KW =14.465,P=0.025, and KW=15.371,P=0.018) respectively.Post-hoc pairwise comparisons revealed that P1 sows had a higher (P<0.001)BFT D109 than P3 and P4 sows.Sows lost 4.24mm of backfat thickness at weaning.The NwP did not differ by parity (P>0.001).Spearman correlation indicated a non-significant (P>0.05)relationship between NwP and BFT D28.The coefficient of determinant (R 2 =0.0437) indicated that 4.37% of variation in backfat loss during lactation can be attributed to number of weaned piglets.In conclusion, regular monitoring of backfat makes it possible to guide sow management.It could enhance sow health, fertility and productivity.