Different durations of whole raw soybean supplementation during the prepartum period: Measures of cellular immune function in transition cows

The objective of this study was to evaluate different durations of whole raw soybean (WS) supplementation (diet rich in n-6 fatty acid) during the prepartum period on cellular immune function of dairy cows in the transition period and early lactation. Thirty-one Holstein cows were used in a completely randomized design and assigned to 4 experimental groups (G) [G90, G60, G30, and G0 (control)] supplemented with a diet containing 12% of WS from 90, 60, 30 and 0 d relative to the calving date, respectively. Cows were dried off 60 d before the expected calving date. After parturition, all cows were fed a diet containing 12% of WS until 84 DIM. Blood samples were collected before the morning feeding (d -56 ± 2, -28 ± 2, -14 ± 2, -7 ± 2, at the day of partum, 7 ± 2, 14 ± 2, 28 ± 2, and 56 ± 2 relative to parturition). Cell phenotyping and phagocytosis assays were carried out using monoclonal antibodies and flow cytometry technique. Duration of WS supplementation linearly increased the percentage of blood CD3⁺ cells, as well as increased the percentage of blood CD8⁺ cells in the postpartum period, notably in G30, whereas the lowest values were observed in G0. Further, the duration of WS supplementation linearly increased the reactive oxygen species median fluorescence intensity of CH138⁺ cells after phagocytizing Staphylococcus aureus in the postpartum period. Longer periods of WS supplementation linearly increased phagocytosis median fluorescence intensity of CH138⁺ cells in the prepartum period of cows. Duration of WS supplementation linearly increased the percentage of blood CD14⁺ cells producing reactive oxygen species when stimulated either by Staph. aureus or Escherichia coli in the postpartum period. In conclusion, longer periods of WS supplementation during late lactation and the dry period (beginning on d 90 of the expected calving date) alter the leukocyte population and improve neutrophil immune response in the postpartum period with no detrimental effects on cow performance.