Impact of the implementation of the mcrebel management program in a commercial breed-to-wean unit following an infection with porcine reproductive and respiratory syndrome
The objective of this study was to determine the effects of the implementation of the McRebel management program on pre-weaning mortality and timing of increase in the percentage of litters testing negative for the Porcine Reproductive and Respiratory Syndrome (PRRS) virus under commercial conditions. The study was carried out at a breed-to-wean facility that had recently tested positive for PRRS 1-7-4 wild type strain. The study used a randomized complete block design (blocking factor was farrowing date) with 2 treatments: 1) McRebel program (involved no cross-fostering with the implementation of additional biosecurity measures to eliminate cross-contamination); 2) Control (cross-fostering according to standard commercial procedures for PRRS negative farms and no additional biosecurity procedures). A total of 4,238 litters housed in 109 rooms forming 54 complete replicates were allotted onto the trial over nine weeks. Room was the experimental unit and a replicate consisted of 2 rooms; treatments were randomly allotted to room. Litter performance measurements were collected from the sow cards that recorded barn, room, crate, parity, sow identification, number piglets born alive and number of piglets weaned. Fluid sampling for diagnostic testing were collected from litters at processing for the McRebel treatment beginning at week 6 of the study; blood sampling for diagnostic testing were collected from litters at weaning for both treatments, beginning at week 7 of the study. The study was carried out for 10 weeks. A total of 18 fluid samples and 240 blood samples for diagnostic testing were collected throughout the study. Litter performance and piglet pre-weaning mortality data for each room were tested for normality and analyzed using the PROC MIXED procedure of SAS. Diagnostic data were analyzed using the Chi-square test using the PROC FREQ procedure of SAS. Pre-weaning mortality was greater (P < 0.05) for the McRebel than the Control treatment in several weeks of the study and for the overall study period (16.87 and 13.13%, respectively). The number of litters testing negative for PRRS did not follow the expected trend. The first fluid samples collected in week 6 of the study were all negative for PRRS for both treatments. Consequently, collection of blood samples at weaning started at week 7 of the study. At this time (week 7 of the study), the percentage of litters testing negative for PRRS was greater (P < 0.05) for the McRebel than the Control treatment. However, for the remainder of the study period (weeks 8-10) there was no difference (P > 0.05) between the 2 treatments for the percentage of litters testing negative for PRRS. Overall, the results of this study suggest that implementing McRebel procedures does increase pre-weaning mortality by 3.74%. The pigs on this study on both treatments became PRRS negative much earlier than expected after the initial infection, therefore, there is a need to repeat the study. In addition, future studies should initiate testing for PRRS much earlier than in the current experiment.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign