What is the 80:20 daytime forage bias?

What is the 80:20 daytime forage bias? 

Have you ever heard of the 80:20 daytime forage bias? It is a feeding concept that is still relatively young in the world of equine nutrition but certainly causing a lot of conversation!  

As horse managers, there are a few facts we know for sure when it comes to our horse’s daily consumption 

1. Horses should consume at an absolute minimum, 1% of their body weight in roughage per day 
2. Under ‘natural’ conditions, our horses spend anywhere between 12-16 hours grazing in a 24-hour period. This is because horses are trickle feeders, meaning they eat smaller meals more frequently, as opposed to just a few large meals.  
3. Extended periods of starvation, and/or poor feeding practices can increase our horse’s risk of health problems, including colic, stomach ulcers, and constipation.  

So, whilst we understand that horses have the capacity to forage for extended periods, do we need to consider when this takes place? And how does this affect our feeding practices? 

Several observations have been made in scientific trials worldwide that have illustrated that approximately 60-70% of foraging takes place during the daytime, whilst the remaining 30-40% takes place during the nighttime. Breaks in eating are filled with times of rest, social behaviours, or comfort activities. These breaks within periods seem to, when foraging is available ad lib, not exceed 3-4 hours between meals.  

The 80:20 daytime forage bias combines these facts to hypothesise that in domestic settings where our horse’s natural foraging behaviours are impaired, we need to alter our feed provisions. The evidence behind the idea was first published by Dr Husted in the Equine Veterinary Journal, in 2009. The study had two groups; Group 1 which was fed for 12h, fasted for 12h, then fed for 24h, and fasted for 24h. Group 2 opposingly had constant feed access. The results concluded that not only did feed deprivation cause rises in gastric pH level, but specifically peaks were most significant when these periods of fasting were during daylight hours.  

These observations have been recently highlighted by Dr Richard Hepburn, a veterinary surgeon and expert in equine internal medicine. Using the work of Husted and others, the 80:20 forage bias has evolved to a concept that suggests that instead of feeding horses with restricted forage access equally across a 24-hour period, we should concentrate the provision during daylight hours. As a result, there would be a potentially lowered risk of health implications, notably gastric ulceration caused by pH rises.  

What does the 80:20 forage bias mean for me and my horse?  

For horses that have free and ample access to roughage, this bias isn’t something that you have control over, and that is no cause for concern. 

However, for horses that have limited access, due to stabling or restricted diets, it is something to consider as part of your overall feeding management.  

For horses that are stabled at night, but have free roughage access during the day, it is of course still highly recommended to provide roughage at night during these periods of restriction. 

However, for horses who may be on overall restricted intakes due to health implications, it may be worth considering that provision of their intake could be fed out in a larger volume during the day, rather than the night.  

As with all things horses, there are lots of factors to consider! If you have any questions about your horse’s nutrition, be sure to reach out to our Nutrition and Health Division by booking a free support call! 

Want to read the science behind it? 

Effect of a feed/fast protocol on pH in the proximal equine stomach. L. Husted, L.C Sanchez, K.E Baptiste, S.N Olsen. https://beva.onlinelibrary.wiley.com/doi/abs/10.2746/042516409X416431  

Biological basis of behaviour in relation to nutrition and feed intake in horses. A.D. Ellis. The Impact of nutrition on the health and welfare of horses. Pages 51-74 https://brill.com/edcollchap/book/9789086867110/BP000012.xml  

Baumgartner M, Boisson T, Erhard MH, Zeitler-Feicht MH. Common Feeding Practices Pose A Risk to the Welfare of Horses When Kept on Non-Edible Bedding. Animals (Basel). 2020 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142811/