The effect of grain type and processing on equine chewing time

Abstract

An experiment was conducted to study the hypothesis that increased grain NDF and feed particle size result in increased chewing time in horse. Three adult Standardbred horses (Group I) and 3 adult Icelandic horses (Group II) were fed 3 daily meals during 3 consecutive days in two 3 × 3 completely randomized block design experiments. Meals of (Group I: 1.0 kg and Group II: 0.5 kg) oats, barley and wheat were fed whole, rolled and ground at 10 am, 12 pm, 2 pm. Chewing activity was measured using a special chewing halter. The basic chewing rate is estimated as jaw movements (JM) per min. Efficient chewing time (EPTIME) in min per kg DM is chewing time corrected for pauses. Regularity of JM is standard deviation of time intervals between individual JM. Faecal particle size was analysed using sieving technique and image analysis. The mean EPTIME was 22 and 15 min/kg DM grain (P<0.01) for Icelandic and Standardbred horses, respectively. The basic chewing rate, chewing regularity and faecal particle size did not differ between horses. The EPTIME for whole grain was 18 min/kg DM but not systematically shorter than for ground grain (20 min/kg DM). EPTIME for oats was 21 min/kg DM but not significantly longer than wheat (18 min/kg DM). Jaw movements were systematically more regular during intake of whole grain as compared to ground grain (P<0.01). In conclusion, the presumed hypothesis could not be accepted. The achieved results indicate that regularity of jaw movements during eating provide a new method for quantifying cereal grain characteristics. The achieved results indicate that regularity of jaw movements during eating provide a new biological method for quantifying cereal grain characteristics.