Chewing analysis of horses consuming bermudagrass hay in different styles of slow feeders as compared to loose hay.

Mastication is the initial phase of digestion and is crucial to equine health due to its role in saliva production and food particle reduction. Hay nets have been promoted to slow the rate of hay consumption, with many styles of slow feeders available. Limited research has shown that nets may slow consumption, but no research has examined their effect on the horse's chewing frequency and patterns. 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), as well as distribution of chews over a feeding period, of horses eating bermudagrass hay in three styles of hay nets [large mesh (LM), small mesh (SM), bottom hole (BH)] as compared to a control of loose hay (CTL). Treatments were assigned in a replicated Latin square 4 × 4 using eight horses. Horses were given a 24-hr acclimation period prior to recording their chewing patterns over a 24-hr period using an automated halter fit with a pressure-sensor noseband. Results indicate that CF was not influenced by treatment. However, SM resulted in longer CD as compared to CTL (P = 0.007). Additionally, BH resulted in a higher percentage of chews completed in the first 240 min compared to SM (P = 0.039), indicating more rapid consumption. Results of this study indicate hay nets may not influence the number of chews a horse performs while masticating hay, but small mesh feeders may increase the CD and reduce early consumption rate.

Effects of stress on chewing and food intake in patients with anorexia nervosa.

OBJECTIVE: The present study investigates the impact of psychosocial stress on chewing and eating behavior in patients with anorexia nervosa (PAN ). METHOD: The eating and chewing behavior of PAN were examined in a standardized setting by means of a chewing sensor. These procedures encompassed n = 19 PAN , age, and gender matched to n = 19 healthy controls (HC). Food intake and chewing frequency were assessed in two experimental conditions: rest versus stress (via Trier Social Stress Test). To verify stress induction, two appraisal scales were employed. In addition, chronic stress, psychological distress and eating disorder symptoms were assessed. RESULTS: In terms of food intake and chewing frequency, the results of the 2x2 ANOVA demonstrated a significant effect of condition and group. During stress, all participants demonstrated a higher chewing frequency and a decreased ingestion. In general, patients ate less at a lower chewing frequency (vs. HC). However, sample specific analyses demonstrated that the eating and chewing behavior of PAN remained unchanged regardless of the condition, except for their drinking. Food choices were comparable between the groups, but appetite values significantly differed. DISCUSSION: The increase in chewing frequency in all participants during stress suggests that chewing might impact affect regulation, however, not specifically in PAN . Future research should clarify to what extent the normalization of chewing behavior could ameliorate ED-symptoms (incl. food intake) in PAN . The application of a chewing sensor could support this aim and future interventions.

Reliability of a novel wearable device to measure chewing frequency.

Purpose In recent years, the chewing frequency, i.e., the number of chewing cycles, has decreased owing to changes in dietary habits. Although these changes may be related to complete body health, there is no evidence-based tool to measure the dietary habits. We developed a small ear-hung wearable device for monitoring mastication behavior. The device, worn on the ear pinna, allows the counting of the number of chewing cycles, and data are collected on a smartphone via Bluetooth. In this study, the reliability of the novel device was verified.Methods A total of 22 healthy volunteers participated in the study. During measurement, the subjects wore the novel wearable device on their right ear pinna and were asked to chew gum, gummy jellies, and rice balls. The number of chewing cycles was counted by the device. A mandibular kinesiograph (MKG) was also recorded, and the chewing activity was recorded as a video. The accuracy, precision, and recall of the ear-hung device were calculated by comparing the data obtained from the MKG and the video recording. Additionally, the factors affecting reliability were examined.Results The accuracy, precision, and recall of the novel device were 101.6 ± 13.6%, 85.3 ± 11.0%, and 84.5 ± 9.5%, respectively. Although the accuracy was not affected by any factor, precision and recall of the novel device for women were significantly worse than that for men, and were greatest when the subjects were chewing gum.Conclusions Our findings suggest that the newly developed ear-hung wearable device for counting the number of chewing cycles was sufficiently reliable.

Effect of biting speed and jaw separation on force used to incise food.

Biting food too quickly might affect the control of jaw-closing muscles and the estimation of bite force. The objectives of this study were to compare the incisal bite forces used to cut food and the activity of masseter (MA) and anterior temporalis (AT) muscles between slow, habitual and fast biting speeds and also between small and large jaw openings. Twenty subjects were asked to use their incisors to cut through a 5 mm thick of chewing gum. In the first experiment, subjects bit at 10-mm incisal separation with slow, habitual and fast biting speeds, and in the second experiment, subjects bit with their habitual speed at 10- and 30-mm incisal separations. The activities in the MA and AT muscles were assessed with surface electromyography, and the bite force was recorded by a force sensor placed beneath the chewing gum. Peak bite forces and associated MA amplitudes were increased significantly as biting speed was increased (P's < .05). Anterior temporalis amplitude was significantly increased during fast biting compared to slow and habitual biting (P's < .001). At 30-mm incisal separation, both peak bite force and AT amplitude were significantly increased, whereas MA amplitude was significantly decreased, compared to those at 10-mm separation (P's < .05). Biting off food quickly with incisor teeth results in larger activities in both MA and AT muscles. In addition, biting a large piece of food resulted in increased activity of AT muscle. Both conditions could be injury stimulator for jaw muscles.

Effect of chewing rate on meal intake.

Fast eating has been shown to increase the risk of overweight in both children and adults. The objectives of the present study were to investigate the correlation between chewing rate and the number of chews per mouthful and to evaluate if they were associated with the weight of meal intake. Thirty healthy subjects, aged 18-24 yr, ate a test lunch at their habitual speed until they felt satiated. The activities of masseter and suprahyoid muscles were recorded to determine the number of chews and the moment of swallowing. The weight of meal intake was recorded along with body mass index (BMI), chewing rate, number of chews per mouthful, meal duration, ingestion rate, hunger, and food preference levels. The mean weight (±SD) of meal intake, chewing rate, and number of chews per mouthful were 261.4 ± 78.9 g, 94.4 ± 13.5 chews min-1 , 19.2 ± 6.4 chews per mouthful, respectively. Chewing rate was not correlated with the number of chews per mouthful. The multivariable linear regression showed that meal intake was significantly positively associated with chewing rate, meal duration, and BMI, but inversely associated with the number of chews per mouthful (adjusted R2 = 0.42). It was concluded that the number of chews was not associated with chewing rate but meal intake was explained by both reduced number of chews and increased chewing rate.

Stress-related laboratory eating behavior in adults with obesity and healthy weight.

Stress is an important factor in the progression of irregular eating patterns and has an additional exacerbating impact in people with overweight and obesity. Therefore, in this study, the chewing and food intake was observed after standardized acute stress induction, as well as resting, in people with obesity and healthy weight controls. Twenty-eight women and men with obesity (BMI: 32.76 ±â€¯2.25 kg/m2) were matched with regard to sex and age to 28 people with healthy weight (BMI: 22.58 ±â€¯2.04 kg/m2). After two conditions (Trier Social Stress Test vs. resting condition) the chewing frequency and food intake were measured during a standardized laboratory meal on two separate days. Additionally, for manipulation check of stress induction salivary cortisol and two appraisal questionnaires (Primary Appraisal Secondary Appraisal, Visual Analogue Scale) were used. People with obesity showed after stress and resting condition a lower chewing frequency in contrast to healthy weight controls (F(1, 54) = 12.816, p ≤ .001). Thereby, both groups demonstrated a higher chewing frequency after the stress induction than after the resting condition (F(1, 54) = 7.436, p ≤ .01). There was no difference between the healthy weight controls and the people with obesity in food intake. In conclusion, the present data indicate a possible 'obese eating style' with regard to chewing performance. Furthermore, the demonstrated higher chewing frequency after stress induction, in people with obesity and people with healthy weight, might be a stress reduction strategy.

Effects of isoenergetic quantities of a low-starch muesli feed high in fat and fibre vs. oat grains on the glycemic and insulinemic responses and feed intake patterns in sport ponies.

Aim of this study was to compare glycemic and insulinemic responses and feed intake patterns in sport ponies after feeding isoenergetic quantities of low-starch muesli feed high in fat and fibre (FF) or oat grains (OG). Six sport ponies were randomly assigned to one of these two treatment groups for 2 × 3 weeks according to a crossover-design. Ponies received two equal meals/day of either semi-crushed OG (1 g starch/kg bwt*meal-1 ) or an isoenergetic quantity of FF. Hay was also given in two equal meals/day and provided the remaining metabolisable energy up to 1.3-fold maintenance level. On day 21, blood was sampled 1 h after each pony received 0.5 kg hay (0 min). Then, the concentrate was provided and blood sampled 30, 60, 90, 120, 180, 240 and 300 min thereafter. Plasma glucose and serum insulin were analysed, and the areas under the curve (AUC) was calculated 120 and 300 min postprandial (PP). Feed intake patterns were measured in 4 ponies/group via a modified halter. OG was ingested faster than FF (feed intake time; FITDM in min/kg DM: 8.8 ± 1.6 vs. 15.9 ± 1.62, p < 0.05) combined with a higher chewing frequency (p < 0.05). The AUCsgluc120/300, ins120/300 were statistically higher with OG than FF (mmol/L*min-1 : AUCgluc120 : 776 ± 128 vs. 676 ± 80.4; AUCgluc300 : 1811 ± 295.3 vs. 1569 ± 126.3; nmol/L*min-1 : AUCins120 : 38 ± 18 vs. 22 ± 8.1; AUCins300 : 83 ± 39 vs. 35 ± 12; p < 0.05). Plasma glucose tended to decline following the intake of FF, which might be beneficial for equines with reduced glucose tolerance. This, however, requires further investigation. In this study, the ponies consumed OG unexpectedly rapidly. The rate of feed intake was similar to the results previously reported in the literature for warmblood horses.

Scaling of rotational inertia of primate mandibles.

The relative importance of pendulum mechanics and muscle mechanics in chewing dynamics has implications for understanding the optimality criteria driving the evolution of primate feeding systems. The Spring Model (Ross et al., 2009b), which modeled the primate chewing system as a forced mass-spring system, predicted that chew cycle time would increase faster than was actually observed. We hypothesized that if mandibular momentum plays an important role in chewing dynamics, more accurate estimates of the rotational inertia of the mandible would improve the accuracy with which the Spring Model predicts the scaling of primate chew cycle period. However, if mass-related momentum effects are of negligible importance in the scaling of primate chew cycle period, this hypothesis would be falsified. We also predicted that greater "robusticity" of anthropoid mandibles compared with prosimians would be associated with higher moments of inertia. From computed tomography scans, we estimated the scaling of the moment of inertia (Ij) of the mandibles of thirty-one species of primates, including 22 anthropoid and nine prosimian species, separating Ij into the moment about a transverse axis through the center of mass (Ixx) and the moment of the center of mass about plausible axes of rotation. We found that across primates Ij increases with positive allometry relative to jaw length, primarily due to positive allometry of jaw mass and Ixx, and that anthropoid mandibles have greater rotational inertia compared with prosimian mandibles of similar length. Positive allometry of Ij of primate mandibles actually lowers the predictive ability of the Spring Model, suggesting that scaling of primate chew cycle period, and chewing dynamics in general, are more strongly influenced by factors other than scaling of inertial properties of the mandible, such as the dynamic properties of the jaw muscles and neural control. Differences in cycle period scaling between chewing and locomotion systems reinforce the suggestion that displacement and force control are more important in the design of feeding systems than energetics and speed.

Chewing after stress: psychosocial stress influences chewing frequency, chewing efficacy, and appetite.

BACKGROUND: Psychosocial stress is accompanied by an increase in the activity of the hypothalamic-pituitary-adrenocortical (HPA)-axis and by an increase in food intake. At present, no studies have been conducted to examine the impact of a potent laboratory stress test on the chewing frequency. METHODS: Thirty-one healthy participants (14 females, mean age 27.13) were compared after they had fulfilled the protocol of a standardized psychosocial stress test, the Trier Social Stress Test (TSST), and after a resting condition of silent reading in reference to their chewing frequency, chewing efficacy, food intake, and eating preferences. As part of the design free salivary cortisol levels and heart rate variability were measured repeatedly before and after the TSST and the resting condition. RESULTS: After the TSST, the participants exhibited a significantly higher mean chewing frequency than after the resting condition (F(2,60)=3.600, p=.035, η(2)=.107). The testing condition had no influence on the amount of food intake. Following the psychosocial stress, however, the participants reported a significantly less general appetite (Z=-3.921, p<.001) and less of an appetite for eggs (Z=-2.023, p=.043) than after their resting condition. No correlation was found between the salivary cortisol response and the chewing frequency. CONCLUSION: The results indicated that psychosocial stress is associated with an increase in chewing frequency, as measured with a sound-based apparatus, and with a decrease in appetite.

The Relationships of Chewing Frequency, Eating Rates, and Food Consumption with the Body Mass Index and Gender of College Students

In this study, we examined chewing frequency, eating rates, and food consumption volume according to the body mass index of male and female college students. Twenty-five male college students were divided into a normal weight male group ( or =23 body mass index, n=11). Twenty-five female college students were divided into a normal weight female group ( or =23 body mass index, n=4). Subjects were provided with abundant fried rice and allowed to consume it at their own pace. Chewing frequency, total mealtime, rate of eating, consumption volume, calorie intake, and the amount of one bite were measured. There were no significant differences in chewing frequency, total mealtime, rate of eating, consumption volume, calorie intake, and the amount of one bite between the normal and obese male groups. There were also no significant differences in chewing frequency, consumption volume, calorie intake, and the amount of one bite between the normal and obese female groups. However, the obese female group had a significantly shorter mealtime and significantly higher eating rate compared with the normal group. Thus, our study suggests that females who eat a meal for a longer time may reduce their food intake, consequently inducing body weight loss.

Development of chewing simulator / 대한치과보존학회지

Chewing simulator, which can partly mimic the motion of chewing motion of human, has been successfully developed. The purpose of its development was to make a new machine which can anticipate the clinical results of restoration in the human teeth more accurately in vitro condition It is composed of 4 major parts; chewing part, motor part, water bath, controlling part. The controlling part control the chewing force, frequency, the temperature and running time of water. Additionally, the actual chewing force and remaining time is shown in the monitor of controlling part. At present, the chewing cycle is composed depending on the pre-published data of foreign people. Long term clinical data should be additionally collected for the simulator to mimic the clinical results more accurately.