The Effect of Prepartum Housing on Metabolic and Reproductive Health in Dairy Cows
The determinants of metabolic and reproductive health disorders and the degree to which housing and management can influence health are only partially understood. The objective of this randomized controlled study was to determine if a prepartum housing strategy of providing non-competitive feeding and lying access improves metabolic health and immune function and reduces reproductive disease. Forty-eight Holstein cows of all parities were randomly assigned to a close up treatment group of 6 to 10 cows in 1 pen with either 80% cows to stalls and 90 cm of feeding space/cow or 120% stocking density and 45cm of feeding space/cow for 3 weeks before expected calving. Pen size and bunk space were adjusted to maintain space per cow as animals were removed for calving. Weekly coccygeal blood samples measured non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), calcium, glucose, albumin, aspartate aminotransferase (AST), bilirubin and haptoglobin from 3 weeks before to 5 weeks after calving. Neutrophil phagocytosis and oxidative burst were assessed at -2, -1, 1, 2, 3 and 5 weeks relative to calving. A modified glucose tolerance test to assess insulin resistance was performed 1 week before calving. Liver biopsies were performed at weeks +1 and +3 to assess liver triglyceride content and gene expression. Vaginoscopy was used to identify cows with purulent discharge (PVD) and uterine and cervical cytobrush samples were collected to assess endometritis and cervicitis as well as uterine gene expression at weeks +3 and +5. There were no interactions of treatment with time. Cows in the crowded treatment had significantly lower mean albumin (P=0.05) and bilirubin (P=0.01) but had greater BHB (P=0.01) and NEFA (P=0.05). At 5 weeks postpartum, 7% of cows had PVD and 33% of cows were diagnosed with endometritis based on > 5% neutrophils. There was no significant effect of treatment on endometritis. Cows that had endometritis at week 5 tended (P<0.1) to have lower average glucose and bilirubin and higher albumin concentrations throughout the study period. These results indicate that metabolic and reproductive health is more complex than can be explained solely by exposure to what is understood to be optimal access to feeding and lying space.
Keywords: endometritis, transition, crowding