|Cary, D - PURDUE UNIVERSITY|
|Johnson, T - PURDUE UNIVERSITY|
Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 9, 2004
Publication Date: November 15, 2004
Citation: Cary, D.C., Eicher, S.D., Johnson, T.A. 2004. Influence of age of transport on toll-like receptors 2 and 4 and interleukin-1 in neonatal dairy calves. Research Workers in Animal Diseases Conference Proceedings. p. 94. Technical Abstract: Transportation of dairy calves, at an early age, is stressful and affects the animal's developing immune system. The purpose of this study was to evaluate the effects of age at transport on blood leukocyte expression of TLR2, TLR4, IL-1, and IL-1Ra. Holstein calves (n=27) were randomly assigned to treatments (age at day of transport); 2-3d (Early), 4-5d (Mid), 6-7d (Late) within a completely randomized block design. Calves were transported (6h) and then placed in individual outdoor hutches. Jugular blood was collected prior to transport (d0) and at d21. RNA was extracted and real time RT-PCR performed to quantify the relative abundance of TLR2, TLR4, IL-1, and IL-1Ra. On d0, TLR2 expression was lower in Mid than Early (P<.01) and tended to be lower than Late (P<.07). On d21, TLR2 expression decreased within all groups (P<.01), and was lower in Mid than Late (P<.05). On d0, TLR4 expression tended to be lower in Mid than Late (P<.07). On d21, TLR4 expression decreased within all groups (P<.01), and was lower in Mid than Late (P<0.05) and tended to be lower than Early (P<0.10). There were no differences in expression of IL-1 or IL-1RA prior to transport (d0). On d21, IL-1 was lower in Early than Mid (P<0.05). On d0, there were no differences in IL-1Ra expression among the groups. On d21, IL-1Ra expression in Early decreased (P<.01) compared to d0. The d0 data suggests that at 4-5 days of age, the calf expresses less TLR. When given a transportation stress, during this time, the calf's immune system remains depressed. The calf's immune system at 2-3 and 6-7 days of age are similar, but calves transported at 2-3 days of age have a depressed expression of IL-1Ra on d21, which may indicate less control over IL-1 responses. These results indicate that day of age of transport is important to the development of the neonatal calf's immune development. These results may impact the management practices (day of transporting calves) of dairy calf growers.