103 Chew frequency and duration in horses consuming bermudagrass hay in slow feeders as compared to loose hay

Abstract

Stabled horses are predisposed to gastrointestinal disorders related to hay consumption. Horses produce saliva when chewing which contains sodium bicarbonate to buffer stomach acid, lubricate a food bolus, and aid in digestion. Chewing hay over a prolonged period allows for buffering of stomach acid to aid in prevention of gastric ulcers. Additionally, increased chewing results in food particle size reduction and improves lubrication to potentially decrease the incidence of impaction colic. Hay nets have been promoted to slow the rate of hay consumption, with many styles of nets and slow feeders currently marketed for horses. No research has yet demonstrated whether hay nets cause the horse to increase their chewing frequency and chewing duration, or whether the slowing effect is simply due to restriction in the amount of forage they can ingest per bite. The objective of this study was to compare chew frequency (CF, total number of chews/kg consumed) and chew duration (CD, total minutes chewed/kg consumed) of horses eating bermudagrass hay in 3 styles of hay nets [large mesh (LM), small mesh (SM), bottom hole (BH)] as compared with a control of loose hay (CTL). Before initiating this project, trial data was collected from 2 horses over 4 d and demonstrated that horses acclimate quickly to hay nets. No differences were seen in CF from day one through d 4 (P = 0.49). Eight horses were then divided into 2 trials, with the4 horses in each trial rotating through treatments in a Latin square design.Each horse was given a 24-h acclimation period to a treatment, and then their chewing patterns were recorded for the following 24 h using an automated halter fit with a pressure-sensor noseband (EquiwatchTM, Liestal, Switzerland). Refused hay was weighed back, and CF and CD were calculated per kg of hay consumed. Data were analyzed using Minitab v.21 (State College, PA, USA) as a mixed model ANOVA with net type as the fixed effect and a post hoc Tukey's test to compare treatments. Data with P < 0.05 were considered statistically different. No treatment difference was noted in amount of hay consumed, with horses chewing an average of 6.8 ± 0.3 kg per treatment. Results indicate no difference between treatments in CF (P = 0.72). CD showed no overall treatment effect (P = 0.27), however, when individual treatments were compared, a statistical difference between SM and CTL was noted (262 vs 189 min respectively, P = 0.001). Results of this study indicate that slow feeders do not influence the number of chews a horse performs while masticating hay, but small mesh feeders do increase the amount of time spent chewing as compared with loose hay.