Exploring the Factors that Surround LDAs

A left displaced abomasum (LDA) is one of the most common transition-cow setbacks that can stall a successful launch into lactation.

LDAs and other digestive disorders can lead to delayed return to ovarian cyclicity, decreased fertility, and lower milk production. Researchers at the University of Florida sought to determine whether pre-calving dry-matter intake (DMI) and/or energy balance could be predictive of the incidence of LDAs postpartum.

Their study, published recently in Frontiers in Veterinary Science, hypothesized that cows with digestive disorders like LDAs postpartum would have experienced a greater reduction in DMI as a percentage of bodyweight (DMI%BW) and/or energy balance (EB) prepartum, and would have a lesser DMI%BW and/or EB, compared to cows without digestive disorders.

The retrospective study examined data from 689 cows in 11 experiments conducted at the University of Florida from 2007 to 2017. About one-third (236) of those animals were first-lactation heifers; the remaining 453 were multigravid cows.

Not surprisingly, cows that experienced LDAs had lower DMI%BW and EB postpartum, compared to cows that did not have an LDA. The LDA cows also had lower energy-corrected milk (ECM) postpartum compared to non-LDA cows, as follows: 

• DMI%BW – Cows that had LDA postpartum had lesser DMI%BW than cows that did not develop LDA on days -24, -23, -12, -7 to 0 leading up to LDA diagnosis, and from days 1 to 8 and 10 to 12, 14, and 16 after diagnosis. 
• Energy Balance – Cows that developed LDA postpartum had lower EB than cows that did not develop LDA from days -7 to -5 -3 to 0, and 12 relative to diagnosis.
• Energy-Corrected Milk – Cows that experienced LDA had lower ECM on days -19 -2, -1, 0, 7, 9, 10, 15, and 17 relative to diagnosis, compared to cows that did not develop LDA.

A previous study by Edwards and Tozer (2004) showed that cows with LDA increased activity in the 10 days prior to diagnosis, which could indicate less time spent at the feed bunk, and thus lower DMI%BW and EB before onset of the LDA. 

In both that study and the Florida one, milk yield for cows with LDA started to decline about 3 days before diagnosis and continued to decrease during the first 7 days after diagnosis compared to cows without LDA.

What was less conclusive about the Florida study was the use of prepartum data as a predictor of postpartum LDA incidence. The average DMI%BW and EB were not significantly explanatory variables to predict LDA.

As it turned out, the only factor that was a significant pre-calving predictor of LDA was parity. Multigravid cows had 9.3 times the odds of developing LDA postpartum compared to first-calf heifers.

The authors concluded that although they believed attention to maintaining DMI and EB prepartum is important for preventing LDA, data from those factors cannot be used to accurately predict which cows will experience LDA after calving.