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Higher masseter muscle activity and chewing frequency with forage

Higher masseter muscle activity and chewing frequency with forage

When horses chew forage they have higher saliva production and gets to chew longer time. Low forage intake leads to different health problems like gastric ulcers, hindgut acidosis and stereotypies. When formulating the horse’s feed ration one always have to make sure it will get enough forage.

In this study horses chewing frequency and masseter muscle activity were examined when feeding different feeds. The masseter muscle activity is the main determinant of salivary flow rate in the oral cavity and in this study masseter muscle activity was measured with electromyography and determined by both amplitude and duration. The feeds tested were hay, haylage (75% DM), straw alfalfa chaff and cracked corn.

The consumption rate was different for the four different feeds in this order: haylage > hay > straw alfalfa chaff > cracked corn, where the horses ate the haylage slowest and the cracked corn fastest. It was the same order for the chewing frequency (chews/kg DM) which was highest for the haylage and lowest for the cracked corn. The masseter muscle activity was higher for the three forages than for the cracked corn in terms of amplitude, but the haylage and hay also had a prolonged duration. The total higher masseter muscle activity for haylage and hay can be due to that they were longer stemmed roughage, the straw alfalfa chaff had a particle length of less than 3.15 cm.

In conclusion consumption of haylage and hay implied intensive masseter muscle activity which should stimulate salivary flow rate. In contrast to the roughages the concentrate cracked corn was consumed rapidly and with lower masseter muscle activity which implies low salivary flow rate and is likely to impair gastric digestion. The study also shows the importance of not having too short particle length on the roughage.

Sara Muhonen, AgrD

Vervuert I, Brüssow N, Bochnia M, Hollands T, Cuddeford D & Coenen M. 2010. Electromyographic evaluation of masseter muscle activity in horses fed different types of roughage. In: The impact of nutrition on the health and welfare of horses, EAAP publication No. 128, pp. 75-77.

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