Interpretive Summary: Far-off and close-up feeding levels affect immunological performance in grazing dairy cows during the transition period.
By: Dr. Caitlin Vonderohe
Approximately 30-50% of dairy cows undergo an infectious or metabolic event immediately following calving. This increase in immune stimulation and metabolic dysfunction can cause serious, detrimental effects on lactation and re-breeding. Previous work has shown that cows also enter an inflammatory state immediately post-calving. This may be rooted in infectious disease, metabolic dysfunction, trauma, stress, or endotoxemia. Previous research has shown that immune function is altered post-calving, which affects the cow’s susceptibility to infectious disease; however, feeding management may positively influence immune function before and after calving.
Lange et al., recently published “Far off and close- up feeding levels affect immunological performance in grazing dairy cows during the transition period in the Journal of Animal Science. During this study authors used gene analysis of immune cells to characterize the immune function of dairy cows fed different energy levels. Understanding the precise effect of body condition score and dietary energy on immune function can help producers make more informed nutrition and management choices in the future.
This experiment used 150 mixed-age and breed dairy cows that were enrolled into one of two dietary treatments approximately 20 weeks before calving. One group of cows was managed to gain minimal body condition during the last eight weeks of lactation and was therefore over-fed during the seven weeks following the lactation period, in the far-off dry period. The other group of cows was managed to gain more condition during the last eight weeks of lactation, and then control fed during the far-off dry period. All cows were subsequently assigned to 1 of 3 levels of energy intake (65, 90, and 120% of estimated maintenance requirements) during the close-up dry period.
Overfeeding cows during the far-off dry period resulted in increased albumin/globulin ratio, reduced blood fatty acid and β-hydroxybutyrate compared to cows that ended lactation with a more optimal body condition and subsequently control-fed during the far off-dry period. Cows fed at 65% maintenance produced less milk during early lactation and had 3x greater haptoglobin (an acute-phase protein) levels post-calving.
Far off feeding affects IL-6 and GAPDH expression in leukocytes, which may affect the survivability of cells in the innate immune system. Cows fed 65% and 90% maintenance energy levels during the close up-transition period expressed higher levels of genes involved in the Th-1 immune response, whereas cows fed 120% maintenance energy expressed genes that may favor a Th-2 response. In general, the transition cow’s immune system expresses fewer activating pathways, and increased inhibition to counter subacute, systemic inflammation. Later, the immune system activates, focusing on activity in mucosal surfaces to combat potential infections in the uterus and mammary tissues. Further research is needed to elucidate the nature and significance of the effect of nutrition on immune responses during the transition period.