Project manager: Anna Jansson, PhD student: Sara Muhonen
Project group: Jan Erik Lindberg, Jan Bertilsson, Véronique Julliand (AgroSup Dijon, Frankrike)
The use of haylage and silage in horse feeding is becoming more and more frequent in Sweden and also seems to become more popular in other parts of Europe. Silage production depends less on weather conditions than hay production, and therefore a feed with high nutritional and hygienic quality can easily be produced. There have been reports of increased faecal water content (slight diarrhoea) and anecdotal reports of reduced exercise performance when feeding or when introducing silage. However, few studies are published on grass silage diets for horses and very few for athletic horses.
Due to different conservation methods the chemical composition of hay and silage differ. Haylage is drier (higher dry matter concentration) than silage and therefore less or no lactic acid fermentation has occurred. Silage contains more water and lactic acid and less sugar since the lactic acid producing bacteria “eats” the sugar. When silage has a higher lactic acid concentration the pH decreases.
Today there is no clear definition separating haylage and silage. The silage quality, popularly, called “cow silage” has a bad reputation among horse owners and trainers. These silages are often characterized by a low dry matter and high lactic acid content with a high energy and crude protein content.
The aim of this thesis was to investigate the effects of forages with different crude protein content and conservation method on metabolism and the colon ecosystem, after abrupt feed changes and after three weeks of adaptation and during exercise and recovery. All studies had a cross-over design, meaning that all horses were tested on all diets in different order.
In conclusion, the studies in this thesis have shown that forage with high crude protein content increase the activity in the colon ecosystem, increase the excretion of nitrogen via urine and faeces and increase the water intake. A change from hay to haylage and silage altered the colon bacterial counts. The feed digestibility was higher for silage than for hay and the silage diet gave an increased water intake. The different diets, different crude protein content and haylage compared to silage, implied no differences during exercise and recovery. However, the increased urine excretion and increased estimated evaporation suggests that a high crude protein intake and silage might be an unnecessary disadvantage during more prolonged exercise when fluid losses might be a limiting factor.
Read the complete thesis (pdf)
Publications:
Muhonen S, Connysson M, Lindberg J E, Julliand V, Bertilsson J and Jansson A 2008 Effects of crude protein intake from grass silage-only diets on the equine colon ecosystem after an abrupt feed change. J. Anim. Sci. 86, 3465-3472.
Connysson M, Muhonen S, Lindberg J E, Essén-Gustavsson B, Nyman G, Nostell K and Jansson A 2006 Effects on exercise response, fluid and acid-base balance of protein intake from forage-only diets in Standardbred horses. Equine vet. J. Suppl. 36, 648-653.
Muhonen S, Julliand V, Lindberg J E, Bertilsson J and Jansson A. 2009 Effects on the equine colon ecosystem of grass silage and haylage diets after an abrupt change from hay. J. Anim. Sci. 87, 2291-2298.
Muhonen S, Lindberg J E, Bertilsson J and Jansson A. 2009 Effects on fluid balance, digestion and exercise response in Standardbred horses fed silage, haylage and hay. Comp. Exercise Physiol. 5, 133-142.
Muhonen S, Lindberg J E, Bertilsson J and Jansson A 2008 Digestibility and plasma glucose and insulin concentrations in athletic horses after abrupt feed changes between grass silage and hay. In: Nutrition of the exercising horse (Eds. Saastamoinen, M. T., Martin-Rosset, W.), EAAP publication No. 125, pp. 93-95. (ISSN 0071-2477)
Muhonen S, Julliand V, Lindberg J E, Bertilsson J and Jansson A 2007 Effects on the equine colon ecosystem following an abrupt change from hay to haylage or silage. Proceedings of the 20th Equine Science Society Symposium, Hunt Valley, MD, USA, 5-8 June 2007, pp. 225-226.
Connysson M, Muhonen S, Lindberg J E, Essén-Gustavsson B, Nyman G, Nostell K and Jansson A 2006 Effects of crude protein intake from forage-only diets on exercise response and acid-base balance in Standardbred trotters. Proceedings of the 7th International conference on equine exercise physiology, Fontainebleau, France, 26-31 August 2006, pp. 207.