180 Effect of Providing Liquid Milk Replacer During Lactation to Litters of Different Size on Piglet Pre-Weaning Performance

Abstract

Abstract Larger litter sizes in commercial sows are generally associated with greater pre-weaning mortality (PWM) and lower piglet weaning weight (WW). Providing liquid milk replacer (MR) to piglets during lactation has been advocated for reducing PWM and increasing WW. The objective was to evaluate the effect of providing MR (using an automated feeder) to litters of different size on PWM and WW. A split-plot design with a 2 x 2 factorial arrangement of treatments was used: 1) MR [main plot; No Supplement (NS) vs. Supplement (SU)]; 2) Litter Size [LS; sub-plot; LOW (4 piglets less than functional teat number) vs. HIGH (2 piglets greater than functional teat number)]. Each MR feeder was available to 2 litters, one on the LOW and one on the HIGH LS treatment. There were 26 sows and litters per MR and LS treatment. Cross-fostering was carried out 24 hours after birth to create LS treatment litters which had similar gender ratio, proportion of cross-fostered piglets, and average and CV of piglet birth weight. Milk replacer was available from 24 hours after birth (day 1; start of study) to weaning (day 20; end of study). Piglets were weighed at the start and end; all PWM was recorded. Piglet weight data were analyzed using PROC MIXED of SAS; PWM data were analyzed using PROC GLIMMIX. Models accounted for the fixed effects of MR, LS, and the interaction, and random effects of replicate and replicate by MR interaction. There was a MR by LS treatment interaction (P ≤ 0.05) for total litter WW and PWM (Table 1). The MR treatment had no effect (P > 0.05) on total litter WW for the LOW LS treatment; however, for the HIGH LS treatment total litter WW was greater (P ≤ 0.05) for the SU than the NS treatment. For the NS treatment, PWM was greater (P ≤ 0.05) for the HIGH than the LOW treatment; however, PWM did not differ (P > 0.05) between the LS treatments for litters that had access to MR. There was no effect (P ≤ 0.05) of MR treatment on litter size or average piglet weight at the start and end of the study. The HIGH LS treatment had greater (P ≤ 0.05) litter size at the start and end of the study, but less (P ≤ 0.05) average piglet WW. In conclusion, increasing litter size above sow functional teat number had negative effects on piglet WW. In addition, providing MR to litters during lactation increased total litter WW in the HIGH but not LOW LS treatment. These results also suggest that providing MR reduced the negative effect of the larger litter size on PWM; however, further research is needed to validate this finding.