Principal Component Analysis (PCA) of the reproductive traits in the Large White sows

UDC 636.4.034 / 57.087.01

DOI: 10.31521/2313-092X/2019-2(102)-11


S. Kramarenko
A. Kramarenko
S. Lugovoy
A. Lykhach
V. Lykhach


      The objective this work was evaluation of the sow’s reproductive traits using Principal Component Analysis (PCA). The population used for the present study is from a pig farm managed by ‘Tavriys’ki Svyni’ Ltd (Kherson region, Ukraine), where the collected data between January 2007 and December 2017 was analyzed. In total, 633 farrow observations were available from 138 Large White (LW) sows.
     Variables measured and derived included total no. piglets born (TNB), no. piglets born alive (NBA), no. of stillborn piglets (NSB), freq. of stillborn piglets (FSB), average piglet birth weight (APBW), pre-weaning mortality in piglets (PWM), no. weaned piglets (NW) and average piglet weaning weight (APWW).
The parities 9 and higher were combined into one parity class (9+), which gave 9 levels for the parity effect. Effect of season of farrowing was analysed in 12 periods: January, February, …, December.
     Litter sizes at birth (TNB and NBA) were positively correlated with no. weaned piglets (NW), but were negatively correlated with piglet birth (APBW) and weaning (APWW) weights. The positive phenotypic correlation between TNB and NSB (and FSB) indicates that piglets born in a large litter are more likely to die than those born in smaller ones.
     Three principal components (PC) accounted for near 80% of the dependency structure existing among the eight reproductive traits in the LW sows. The first principal component (PC1) accounted for 33.6% of the total variance and was influenced by TNB and NBA. Thus, PC1 may be interpreted as “potential fecundity of sows”. The second principal component (PC2) accounted for 27.1% of the total variance and linked to NBA (positive), NSB and FSB (negative). Therefore, PC2 may be interpreted as “realised fecundity of sows”. At last, the third principal component (PC3) derived from the LW sow’s reproductive traits accounted for 18.7% of the total variance and contrasted sows having large no. weaned piglets and low pre-weaning mortality in piglets with sows having small no. weaned piglets and high pre-weaning mortality in piglets.
     Number of parity had a significant effect on the sow’s reproductive traits. Thus, TNB in the LW sows increased to the 5th parity and then decreased. Liveborn litter size (NBA) decreased after the 4th parity rapid. Season of farrowing did not significantly affect potential and realised fecundity of sows. However, the number of weaned piglets was the highest in sows farrowed in June-September, and the lowest in sows farrowed in winter.

     Keywords: reproductive traits, Principal Component Analysis (PCA), parity, season of farrowing, sows.


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