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Arkansas Animal Science Department Report 2001
indirect staining procedure and flow cytometric analysis
(Park et al., 1992). The functions of each of the cell types
measured are described in Table 1.
Cow and calf serum concentrations of IgG were measured
0 and 24 h post partum. Serum IgG was assessed using
a commercial radial immunodiffusion kit (VMRD, Pullman,
WA). Cow and calf serum concentrations of Cu and Zn were
measured 0 and 24 hr post partum.
Analyses of variance were conducted on proportions of
leukocyte populations, MGS and serum data using SYSTAT
9.0 software (SPSS Inc., Chicago, IL 60606). The model
included Tasco, sampling time, and the Tasco by sampling
time interaction.
Results and Discussion
Where there were no dietary treatment by time of sampling
interactions (P > 0.10), the main effects of dietary treatment
and time of sampling will be discussed.
In cows, supplementation of Tasco TM increased the
proportion of B lymphocytes (P = 0.05) in the blood (Table
2). Tasco TM decreased the proportion of helper T lymphocytes
(P = 0.03) and tended to decrease the proportions of γδ
T cells (P = 0.13) within the lymphocyte population. γδ T
cells are T lymphocytes that are predominantly associated
with immune function at epithelial and mucosal surfaces.
Proportions of bovine leukocyte populations in the
MGS were affected by time of sampling and dietary treatment
(Table 3). T lymphocytes migrate selectively into bovine
milk. T cells in milk express cell surface markers that are
characteristic of memory T cells (Taylor et al., 1994).
Additionally, T cells in the milk are predominantly positive
for cell surface markers (CD8+), suggesting cytotoxic function
(Asai et al., 2000). B lymphocytes represent a minor population
in milk when compared to peripheral blood. The proportion
of B lymphocytes tended to increase from parturition
to d 1 (P = 0.13). Tasco supplementation tended to increase
the proportion of monocytes/macrophages in the mammary
gland secretions (P = 0.06).
Proportions of B lymphocytes in blood from calves
decreased (P = 0.03) due to Tasco TM supplementation (Table
4). Proportion of granulocytes and monocytes/macrophages
in the blood of calves increased from parturition to d 1 (P <
0.03). The proportions of helper T lymphocytes tended to
increase and B lymphocytes increased in the blood of calves
from birth to d 1 (P = 0.13 and P = 0.04, respectively).
Tasco supplementation had no effect on the concentration
of IgG (Table 5) in the serum of cows or MGS (P >
0.10). Mammary gland secretion IgG concentrations
decreased from parturition to d 1 (P < 0.01). This finding is in
agreement with previous reports that noted a decrease in
MGS IgG concentration several days after parturition
(Quigley and Drewry, 1998). Serum IgG concentrations from
calves born to cows consuming the Tasco supplement did
not increase as much from d 0 to d 1 as did the non-supplemented
group (sampling time x Tasco interaction, P < 0.01;
Figure 1).
In cows, supplementation of Tasco had no effect on
the concentrations of Cu in the serum (Table 6). However,
Tasco TM supplementation decreased (P = 0.05) serum Zn concentrations
in the cows. Time of sampling significantly
increased the Cu concentration in the serum of calves (P <
0.01) and tended to decrease the serum Zn concentration
(P = 0.09).
Implications
Dietary supplementation with Tasco TM altered proportions
of bovine leukocyte populations in blood and mammary
gland secretions. The impact of Tasco TM supplementation
on cow and calf health requires further investigation.
Determining the basic mechanisms involved in passive
immune transfer from the cow to the calf at parturition could
be economically advantageous to the dairy cattle producer.
Acknowledgements
The authors would like to thank the BoNaRaDo Farms,
especially Bob, Nadine, and Randy Spears for all of their help
in accommodating the researchers as well as managing the
research cattle. The authors would also like to acknowledge
Land O’Lakes Farmland Industries and Acadian Seaplants
Ltd. for their generous donations of feed and research support.
Literature Cited
Allen, V. G., et al. 2001. J. Anim. Sci. 79:1032.
Asai, K., et al. 2000. Vet. Immunol. Immunopathol. 73:233.
Fike, J. H., et al. 2001. J. Anim. Sci. 79:1011.
Park, Y. H., et al. 1992. J. Dairy Sci. 75:998.
Quigley, J. D., and J. J. Drewry. 1998. J. Dairy Sci. 81:2779.
Saker, K. E., et al. 2001. J Anim. Sci. 79:1022.
Taylor, B. C., et al. 1994. Cellular Immunology. 156:245.
Wittum, T. E., and L. J. Perino. 1995. Am. J. Vet. Res.
56:1149.
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