Poster
The effect of pair housing on immune development in response to weaning and social mixing in dairy calves
| Date/Time: |
9/12/2024
|
| Author: |
Kendra N Pachniak |
| Clinic: |
University of Minnesota |
| City, State, ZIP: |
Falcon Heights, MN 55108 |
K.N. Pachniak, BS, MS
1
;
L.S. Caixeta, DVM, PhD
1
;
M.C-J. Cheeran, BVSc&AH, MVSc, PhD
1
;
S.M. Godden, BSc, DVM, DVSc
1
;
N.R. Noyes, BA, MA, DVM, PhD
1
;
W.A. Knauer, BS, VMD, PhD
1
;
1Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, 55108
Introduction:
A majority of dairy operations in the US house calves individually prior to weaning and social mixing. As a result of individual housing, dairy calves have shown increased amounts of stress behaviors during the weaning and social mixing transition, and often have an increase in disease occurrence. It is unclear how individual housing may be impacting calves’ immune development during this time period. This study assessed the impact of housing type prior to weaning on immune development (through the expression of five cytokine genes) during weaning and post-weaning social mixing.
Materials and methods:
Thirty Holstein heifer calves were enrolled in one of two treatment groups within 7 days after birth: pair housed (pair; n=20; 10 pairs) or individually housed (ind; n=10). Calves in both treatment groups were housed in outdoor hutches, (two hutches side-by-side for each pair; one hutch for individual calves), and managed via the same standard operating procedures throughout the study. All calves were weaned from days 43-56 and spent an additional 7 day adjustment period, post-weaning, in the hutches. Calves were socially mixed within their treatment group on day 63 of age. Whole blood was collected one week prior to the start of weaning, on days 43, 44, 46, 48, and 50, relative to weaning and on days 63, 64, 66, 68, and 70, relative to social mixing. White blood cells were harvested from the whole blood, the RNA was extracted, and cDNA was synthesized. The cDNA was used for the determination of gene expression (as CT values) for five cytokine genes (IL1-β, TNF-α, TLR-4, MPO, and SELL) and one reference gene (RPL-19) through real time qPCR. A mixed effect model with repeated measures to determine effects of sampling periods, housing type (pair vs individual), and the interaction between the two; this model also accounted for repeated measurements within calves and the random effect of pair. Final significance was determined at P≤0.05.
Results:
We observed no evidence of an effect of housing type (pair vs. ind) on the average CTs in the genes evaluated overall [RPL-19 (pair= 21.73 ± 0.04, ind= 21.81 ± 0.04, P=0.18), IL1-β (pair= 25.80 ± 0.08, ind= 25.70 ± 0.11, P=0.61), TNF-α (pair= 28.71 ± 0.06, ind= 28.75 ± 0.07, P=0.74), TLR-4 (pair= 29.90 ± 0.09, ind= 29.80 ± 0.10, P=0.34), MPO (pair= 32.40 ± 0.13, ind= 32.30 ± 0.17, P=0.80), and SELL (pair= 24.35 ± 0.05, ind= 24.28 ± 0.06, P=0.33)]. We also observed no evidence of an effect of housing type on gene expression over time [RPL-19 (P=0.88), IL1-β (P=0.38), TNF-α (P=0.45), TLR-4 (P=0.60), MPO (P=0.14), and SELL (pair= P=0.11)]. We also did not observe a change in expression of RPL-19, IL1-b, TLR-4, MPO or SELL over the observation period. However, we did observe an overall increase in expression of TNF-alpha over the study period (average CT of 28.90 observed at baseline, and 28.70 observed at 70d; P=0.004).
Significance:
Under the conditions of this study, we observed no evidence of an effect of pair vs individual housing on the expression of RPL-19, IL1-β, TNF-α, TLR-4, MPO, and SELL cytokine genes either overall, or over time. We did observe an increase in expression of TNF-α over time, but this change was very small. Future analysis will evaluate the effect of pair vs. individual housing on immune function and cortisol response to weaning and social mixing.
