Please read Part 1, Forage and Pasture, before reading this!
Part 1 covers the basics of EMS, the aims and objectives of feeding horses with EMS, and all types of insulin dysregulation, like laminitis.
Compound feed
Ensuring a balanced ration alongside facilitating a calorie deficit is often overlooked but should not be discounted. Forage only diets, particularly where intake is restricted are unlikely to meet the micronutrient and quality protein (amino acids) requirements (NRC, 2007; Equi-analytical Laboratories, 2024). The latter important for maintenance of lean muscle mass.
Pelleted balancer products are widely available and provide vitamins, minerals and quality protein when fed at typical rates of 100g per 100kg bodyweight. Alternative options include fortified chaffs and soaked fibre feeds, while either may be suitable, ‘as fed’ volumes can appear large which can result in underfeeding and inadequate nutrient provision. The latter can be extremely useful for maximising chew time and slowing consumption rate when fed in the recommended quantities.
Building on previous work (Macon et al., 2022), further research has identified a potential threshold per meal for ID horses of around 0.1g/kg bwt/meal Non-Structural Carbohydrate (starch and sugar combined (Macon et al., 2021). To put this into context, this would be 50g for a 500kg horse and most balancers at 10-12% combined starch and sugar when fed at the recommended daily rate (100g per 100kg bodyweight – 500g for a 500kg horse) would provide 50-60g of starch and sugar combined, emphasising the potential importance of dividing the ration across multiple smaller meals. While further research is required to ascertain if this can be extrapolated more widely, it offers a good starting place for rations.
In addition, salt should also be fed (30g of table salt per day will provide 12g of sodium which is sufficient to meet the maintenance requirements of a 500kg horse) alongside vitamin E for those without access to fresh forage (NRC, 2007).
Feed Management
Weighing all feeds (dry weight) and not feeding by volume is an essential part of feed management where weight loss is concerned (Honore and Uhlinger, 1994). All feed should be weighed and considered as part of the ration, however small. When weighing out forage in nets or other feeders, be sure to consider the weight of the forage presentation (average haynets weigh between 0.4-0.6kg, hay balls as much as 2kg).
Using methods to extend ‘chew-time’ (thereby reducing duration without forage (≤5 hours where possible (Shepherd et al. 2021)) while promoting opportunity for natural behaviour and a range of feeding positions is key where dietary restriction is ongoing. Dividing the forage ration throughout the day, creating multiple feeding sites (Ellis et al. 2015) and using small-holed nets or feeders has been shown to extend chew time (Aristizabal et al. 2013; Hallam, et al. 2012; Glunk et al. 2014; Morgan et al. 2016; Rochais et al. 2018) and thereby reduce the risk of long periods without forage. Note that effectiveness of interventions to slow consumption is reported to vary between individuals and may wane overtime (Ellis et al. 2015). Further research on their implementation and impact on behaviour however has highlighted potential as a source of frustration (Rochais et al. 2018), however their use has also been highlighted as a means of improving welfare of stabled horses (Correa et al. 2020). Where incorporating these in a weight loss programme, intake and behaviour should be monitored regularly. Anecdotally, using a combination of feeders along with a small amount of forage offered free choice can help to reduce frustration behaviours.
The same focus can be applied to bucket feeds, using larger diameter shallow containers which spread feed over a larger area, encouraging smaller mouthfuls and thereby extending eating time can be useful. Additionally, traditional management to prevent bolting feed (and choke) can also be applied, for example the addition of two large smooth stones or similar immovable objects (boules/bocce style balls can work well). Alternatively, purpose made slow feeders like the Grad-Dual Feeder or Shake and Graze nets (for chaff) could be considered. As with all feed management supervise use initially and mix things up to try and reduce any frustration/stress. To monitor how successful each intervention is, roughly time the consumption time and compare against the baseline for the current presentation.
Other methods to employ include physically staggering feeding times and/or splitting the bucket feed across several bowls placed in different places the stable or paddock – with hay nets, this has been indicated to extend eating time and therefore is worth a try. Providing hay before a bucket feed (especially if they may have been without feed for a period of time) and/or adding a few handfuls of loose hay on top of the bucket feed may also help to moderate consumption speeds.
Key Points for implementing a successful management plan:
- Initial assessment of the horse, ration, management, and facilities should inform the proposed weight management plan.
- Regular ‘check-ins’ with a vet or other paraprofessional has been shown to improve compliance and should also help to ensure that the plan is adjusted in a timely manner where progression is not as expected. The weight loss plan should include review points and encourage regular recording of bodyweight and condition.
- While various medications can be prescribed by your vet, for ID, medication is not a substitute for diet and other management changes, the approach should be inclusive of all these factors.
- For cases where a resistance to weight-loss is apparent forage intake may need to be reduced below 1.5% bodyweight (target or current) dry matter. Note this should only be done under veterinary (and nutritionist) recommendation.
- Sustainable weight loss takes time – for those that are overweight a timeline of 9-12 months before significant changes are observed is not uncommon.
