Larger Meal Size Research Articles

Why do some fish grow faster than others?

AbstractAll animals must acquire food to grow, but there is a vast diversity in how different species and even different individuals approach and achieve this task. Individuals within a species appear to fall along a bold‐shy continuum, whereby some fish acquire food aggressively and with seemingly high risk, while others appear more submissive and opportunistic. Greater food consumption generally results in faster growth, but only if the energy acquired through food is more than enough to compensate for heightened metabolism associated with a more active lifestyle. Fast‐growing phenotypes also tend to have elevated baseline metabolism – at least when food is plentiful – which may be linked with gut morphology and digestive efficiency. The net energy gained from a meal (as calculated from the specific dynamic action (SDA) coefficient) is optimised with larger meal sizes, but the digestion of large meals can erode the aerobic metabolic scope available for other critical activities such as predator avoidance, perhaps at an interindividual level. Thus, complex interactions between an individual's genes and environment are likely to regulate the growth phenotype. This review compiles available knowledge to shed light on the question: Why do some fish grow faster than others? We discuss the elaborate interrelationships between behaviour, physiology and the gut microbiome with a goal to better understand what drives interindividual differences in growth performance.

Effect of meal size on the postprandial metabolic response in Chinese giant salamander Andrias davidianus larvae

The digestive physiological characteristics of Chinese giant salamander Andrias davidianus have not been reported in the existing literature, and improving our knowledge in this area could help in the artificial culture of the species. The effect of meal size on the specific dynamic action (SDA) of A. davidianus larvae was assessed in this study at a water temperature of 20°C. The Chinese giant salamander was fed by test diets at meal sizes of 0.5, 1, 2, 4, 8 and 12% of its body mass (4.41 ± 0.07 g), and the postprandial oxygen consumption rate (MO2) was measured at 2 h intervals until the rate returned to its preprandial level. Peak MO2 (MO2peak) increased with meal size but levelled off at larger meal sizes within the studied range (8-12% body mass). The factorial metabolic scope increased from 1.27 to 2.11 when meal size increased from 0.5 to 12%. Time to reach MO2peak was not affected by the relative meal size. The SDA duration increased from 8.89 to 47.33 h as the relative meal size increased from 0.5 to 12%. The amount of energy expended during SDA increased linearly with increasing meal size (R2 = 0.842, p < 0.001, n = 60). There was no significant difference in the SDA coefficient among the different relative meal size groups. These data suggest that (1) A. davidianus larvae increase their energy demands during digestion by prolonging the SDA duration rather than increasing the MO2peak as meal size increases, and (2) A. davidianus showed a smaller factorial metabolic scope in the process of digesting large meal sizes, which may be related to the limited MO2peak of the species.

Intestinal adaptations to energy source of milk replacer in neonatal dairy calves

Most milk replacers (MR) contain more lactose compared with whole milk, which, when fed at a large meal size, could influence gut barrier function in calves. This study evaluated how replacing lactose in MR with fat (on a wt/wt basis) affects intestinal histomorphology and permeability in neonatal dairy calves. Thirty-four Holstein-Friesian bull calves were blocked by dam parity and randomly assigned to 1 of 2 treatments (n = 17): a high-lactose (46.1% lactose, 18.0% crude fat, and 23.9% crude protein of dry matter) or a high-fat MR (HF; 39.9% lactose, 24.6% crude fat, and 24.0% crude protein of dry matter). Calves were individually housed and fed pooled colostrum at 1.5 h and 12 h postnatally, at 18 and 9% of metabolic body weight (BW0.75), respectively. From 24 h postnatally until the end of the study (d 7), calves were transitioned to be fed MR (prepared at 15% solids) at 18% of BW0.75 twice daily at 0700 and 1900 h. During postprandial sampling on d 6, intestinal permeability was assessed by mixing lactulose (1.03 g/kg of BW0.75) and d-mannitol (0.31 g/kg of BW0.75) into the morning meal without altering total meal volume. Sequential blood samples were collected via jugular catheter, and total urine was collected for 12 h to measure the marker content. Calves were euthanized 3 h after the morning meal on d 7, and gastrointestinal tract tissues and digesta were collected for analysis of histomorphology, digesta osmolality, and gene expression. The empty gastrointestinal tracts of HF calves were heavier, although length did not differ and differences in histomorphology were minor. Digesta osmolality changed along the tract without differences between treatments. Plasma lactulose was greater in HF, although plasma d-mannitol and the recovery of both markers in urine were unaffected. No significant differences were detected in gene expression, although HF calves tended to have lower expression of TJP1 and CLDN2 and higher expression of proinflammatory cytokine IL1B in ileum tissue. In conclusion, partially replacing lactose in MR with fat resulted in a heavier and more permeable gut, with minor histomorphological differences.

721-P: Fat Added to High-Glycemic–Index Foods Reduces Both Glycemic and Insulinemic Response to Moderate-Size Meals

Fat has been shown to be a powerful modifier of dietary glycemic response (Flint et al 2004). But other research shows addition of fat to high GI meals worsens insulinemic response (Gannon et al 1993). The author hypothesized that researched insulin response was more related to excessive meal size (50+ gms of both carbohydrate and fat) than to fat content per se. The current study compared starch or sugar based nonfat 50 gm carb meals (∼250 kcal) with meals containing 30 gm amounts of both fat and carb (∼450 kcal) in 12 healthy 21-75 year old volunteers (6-8 per subgroup) without glucose intolerance. Size of subgroups was similar to that used in establishing the glycemic index (Jenkins et al 1981). Each subject served as their own control. Despite the larger meal size, the balanced carb/fat meals had lower glycemic and insulin responses, with p values of 0.009 and 0.016 for glycemic response, and 0.014 and 0.0275 for insulin response to starch and sugar-based meals, respectively (Wilcoxson, one tailed). Post-study interviews also demonstrated that subjects preferred the balanced meals. This pilot study has demonstrated that adding fat to moderate sized meals lowered, not raised, insulin levels, even when compared to much smaller nonfat meals. It also confirms previous research that fat lowers glycemic response and improves palatability. Taken together, these findings support further research into the potential benefit of balanced carb/fat meal combinations. Such meals might improve diet sustainability as well as efficacy. Future research can explore other fat types/amounts, and evaluate the utility of this concept in real world dietary management. Disclosure D.K. Jass: None.

Nutritive value for high-yielding lactating cows of barley silage and hay as a substitute for wheat silage and hay in low-roughage diets

We assessed the effects of replacing wheat silage and hay with barley silage and hay in total mixed rations (TMRs) on: eating behavior, digestibility, and performance of individually fed high-yielding lactating cows. The barley cultivar Ma’anit and the wheat cultivar Omer were grown by dryland farming (210 mm precipitation) in a commercial field with sandy loam soil. The two cultivars were harvested simultaneously for silage or hay at a similar dry matter (DM) content (35.6%). Barley yields exceeded wheat yields by 19% (5.68 vs. 4.79 t DM/ha, P = 0.01). Two-thirds of each crop's DM yield was chopped and transferred for direct ensiling in polyethylene-wrapped bales, and one-third was wilted in the field for 2 weeks and then pressed into hay bales. The chemical composition and in-vitro DM digestibility of the wheat and barley silages and hays were similar. The two experimental TMRs contained either barley silage (280 g/kg DM) and hay (60 g/kg DM) or similar contents of wheat silage and hay, as the sole source of roughage. High-yielding multiparous Israeli Holstein cows were paired into two experimental groups of 21 cows each and fed either wheat- or barley-based TMR ad libitum for 28 days. DM intake of cows fed the wheat TMR was higher than that of the barley TMR-fed cows (28.0 vs. 27.5 kg/day) due to a faster eating rate (137.9 vs. 132.9 g DM/min) and larger meal size. Energy corrected milk production was similar in the two groups (42.4 and 42.8 kg/day), while milk fat yield was higher in barley-fed cows than wheat-fed cows (1.62 vs. 1.57 kg/day). Daily rumination time of the barley-fed cows was longer (577 vs. 537 min/day) and their rumen pH higher during the day and night (P < 0.01) compared to wheat-fed cows. Consequently, in-vivo DM digestibility and neutral detergent fiber digestibility were higher in the barley-fed cows. Our results thus show the benefit of barley as an alternative forage crop to wheat in semiarid regions, and its advantage as a substitute for wheat as silage and hay for high-yielding lactating cows’ TMR.

A blend of essential oils improved feed efficiency and affected ruminal and systemic variables of dairy cows.

This experiment evaluated the effect of a blend of essential oils (BEO) on intake, lactation performance, diet digestibility, ruminal fermentation profile, eating behavior, body thermoregulation, blood acid–base balance, and milk fatty acid profile of lactating cows. Twenty-eight Holstein cows were individually fed a standard diet for 14 d and treatments control or BEO (a microencapsulated blend of pepper extract containing capsaicin and pure forms of carvacrol, cinnamaldehyde, and eugenol; 150 mg/kg of diet dry matter) for 56 d. Significance was declared at P ≤ 0.05 and trends at 0.05 < P ≤ 0.10. Dry matter intake (DMI) was reduced (19.5 vs. 20.1 kg/d) and milk yield was increased (30.1 vs. 30.8 kg/d) by BEO, inducing improved milk to DMI ratio (1.53 vs. 1.62). Milk fat concentration tended to be increased by BEO, but total solids yield did not differ. There was a trend for increased total tract non-neutral detergent fiber organic matter digestibility with BEO. The molar proportion of acetate in ruminal fluid was reduced (51.4 vs. 57.8%) and that of propionate was increased (26.1 vs. 31.3%) by BEO. Ruminal microbial yield and total protozoa count in ruminal fluid did not differ. Cows fed BEO ingested a greater proportion of the daily intake in the morning (30.6 vs. 36.6%) and tended to ingest a lower proportion at night, tended to have longer meals, and had fewer meals per day (11.9 vs. 13.7) and larger meal size (1.5 vs. 1.7 kg of dry matter per meal). Blood urea-N and glucose concentrations did not differ. The BEO increased jugular blood oxygenation. The sweating rate on a hot and dry day was increased (160 vs. 221 g/m2/h) by BEO. The mean rectal and skin temperatures and respiration rate did not differ, but the proportion of rectal temperature measurements ≥39.2 °C was reduced by BEO at 1400 h (17.8 vs. 28.5%) and 2000 h (23.2 vs. 34.8%). The BEO increased the secretion (g/d) of 18:2 trans-10, cis-12 and the concentration of 18:0 iso fatty acids in milk fat. When one sample of milk from BEO cows was offered with two samples of milk from control, 59% of regular consumers of milk (n = 63) identified the odd sample correctly. The gain in feed efficiency induced by BEO was associated with reduced acetate-to-propionate ratio in ruminal fluid, altered eating behavior, lower frequency of high rectal temperature, and increased blood oxygenation. Essential oils had positive effects on ruminal fermentation and systemic variables of dairy cows.

404 Awardee Talk - Healthy gut, healthy calf, productive life

Abstract The calf undergoes major transformations in early life that make it more susceptible to gastrointestinal tract (GIT) disease and disorders compared to all herd-mates. One of the most critical management factors in calf survival and health is feeding a sufficient amount of high-quality colostrum in order to improve passive transfer. However, further benefits to GIT function and health are now also being recognized. It has recently been shown that a delay in colostrum feeding of only six or twelve hours after birth can impact not only passive transfer but also the colonization of healthy bacteria (Bifidobacterium) in the small intestine of newborn calves. In addition, the heat treatment of colostrum has been shown to increase the colonization of Bifidobacterium and decrease the colonization of Escherichia coli in the small intestine of calves during the first 12 hours of life. New research is showcasing how the transition from colostrum to milk in the first days of life is critical to GIT development. For example, calves that transition directly to milk after the first meal of colostrum have less overall GIT mass and small intestinal villi development compared to calves fed transition milk or colostrum at three days of life. Based on these preliminary findings, there is a need to consider other bioactive components in colostrum and transition milk that impact GIT development in order to provide the calf with the best chance to combat GIT ailments later in life. With respect to the pre-weaning period of calf production, the amount of milk to be fed to calves has been a hot topic in the past decade, as it directly impacts pre-weaning average daily gain, which may be associated with lifetime production. Most dairy calves are only fed two meals per day and it is thought that increasing meal sizes may cause milk overflow into the rumen, resulting in digestive upsets and hyperglycemia. What recent research has shown however is that the GIT of the calf has a certain degree of plasticity and can adapt to large meal sizes (10% of birth bodyweight) in the first weeks of life by altering abomasal emptying as a means of controlling nutrient delivery to the intestine, thereby stabilizing blood metabolites such as glucose. In addition, new research investigating milk replacer composition, which is higher in lactose and lower in fat compared to whole milk, shows differences in abomasal function that may lead to a negative impact on insulin sensitivity. This research suggests that we have been underestimating how much milk calves can consume and how new milk replacer formulations may be impacting GIT health. An improved understanding of how diet, microbiota, and biomolecules interact to impact growth and barrier function of the calf’s GIT would greatly benefit the industry. A mechanistic understanding of such adaptations would also aid in the formulation of specific management regimens and the provision of diets that support or enhance gut function in young calves.

Effects of rate and amount of propionic acid infused into the rumen on feeding behavior of Holstein cows in the postpartum period

The objective of this study was to determine the effects of 2 amounts of propionic acid (PA) infused intraruminally at 2 rates of infusion at the initiation of meals on the feeding behavior of Holstein cows in the postpartum period. We hypothesized that the amount and length of time of infusions would interact to affect feeding behavior: rapid infusion of a higher dose of PA would result in larger meal size with greater time between meals compared with a slower rate, whereas faster infusion of a lower dose of PA would reduce meal size and the time between meals compared with a slower infusion of the same dose. Eight ruminally cannulated, multiparous Holstein cows were used in a 4 × 4 Latin square design experiment. Cows were blocked by parturition date and randomly assigned to treatment sequence within square. Treatments were infusion of 2.5 L of 0.5 M (HI) or 0.2 M (LO) solutions of PA at initiation of meals over 5 min (FST) or 15 min (SLW) for 12 h following feed delivery. Contrary to our hypothesis, no interaction between amount and rate of infusion was detected for any feeding behavior parameter measured. The FST treatments did not affect dry matter intake or metabolizable energy intake compared with SLW. The FST treatments tended to increase meal length compared with SLW (28.1 vs. 22.7) but did not affect meal size. The FST treatments tended to decrease total eating time (108 vs. 122 min/12 h) but did not affect meal frequency compared with SLW. The HI treatments decreased dry matter intake (7.4 vs. 11.5 kg/12 h) and total metabolizable energy intake (22.5 vs. 29.1 Mcal/12 h) compared with LO by decreasing meal frequency (5.8 vs. 7.5 meals/12 h). The HI treatments decreased eating time (103 vs. 127 min/12 h) compared with LO but did not affect meal size. Further research is warranted on the effects of the temporal supply of propionate on propionate metabolism and feeding behavior.

Effects of flavonoids extracted from Citrus aurantium on performance, eating and animal behavior, rumen health, and carcass quality in Holstein bulls fed high-concentrate diets

The effects of flavonoids extracted from Citrus aurantium (Bioflavex® CA) on eating pattern, performance, carcass quality, and rumen wall health of Holstein bulls fed on a single feeder were studied. One hundred ninety-eight bulls (195.3 ± 19.6 kg of body weight and 149 ± 6.8 d of age) were used in a complete block randomized design. Groups of animals with the same mean and coefficient of variation of body weight (replicates) were randomly allocated in 1 of 6 pens (20 animals per pen), and each pen was assigned to one of 6 pens and assigned to a Control (C) diet or to a diet supplemented with flavonoids (Bioflavex® CA, Interquim S.L., Spain) (BF, 0.4 kg per ton of concentrate of Bioflavex® CA) in two consecutive fattening cycles. Concentrate intake was recorded daily, and BW fortnightly. Animal behavior was monitored by visual scan procedure every fourteen days. Animals were slaughtered after 168 d of study, hot carcass weight and carcass quality were recorded, and internal rumen wall was examined. Concentrate intake was higher (P < 0.05) in C than in BF bulls; however, ADG and concentrate efficiency were not affected by treatments. The final BW tended (P = 0.06) to be higher in C than in BF bulls, but this difference disappeared for carcass weight. In the finishing phase, the proportion of meal size values above 750 g was higher (P < 0.05) in C compared with BF bulls. Throughout the study exhibited more displacements and fighting than C bulls, whilst C bulls performed more (P < 0.05) oral behaviors. During the finishing phase, sexual behaviors such as flehmen and complete mounts were higher (P < 0.01 and P < 0.05, respectively) in C bulls as well, and C bulls tended (P = 0.10) to perform more attempted mounts compared with BF bulls. In the slaughterhouse, color of rumen wall tended (P = 0.06) to be lighter for BF compared with C bulls, and presence of baldness areas in the rumen was lesser (P = 0.01) in BF animals. In conclusion, when bulls were supplemented with Bioflavex® CA, feed intake was reduced. Flavonoids supplementation increased time eating straw, reduced agonistic behaviors throughout the study and sexual interactions during the finishing phase, potentially improving animal welfare. Rumen wall parameters analyzed were indicative of a better rumen health in BF than in C bulls, which maybe due to the reduction of large meal sizes.

Sheep residual feed intake and feeding behaviour: are ‘nibblers’ or ‘binge eaters’ more efficient?

Efficient liveweight gain is an important component of profitable livestock systems. In cattle, studies of residual feed intake (RFI) suggest that there are behavioural differences between efficient and inefficient animals; more efficient animals have less frequent, larger feed events. There is limited understanding of the association between feeding behaviour and feed conversion efficiency (measured as RFI) in sheep. We hypothesised that more efficient sheep would have lower daily number of meals but larger meal size than would less efficient sheep and that feeding behaviour would be repeatable between measurements conducted using the same sheep at different ages. Feeding behaviour was monitored at post-weaning (average 311 days) and hogget (average 533 days) age in a single cohort of maternal composite 2014-born ewes undergoing feed-efficiency testing. Feed intake (kg/day) and daily feeding behaviour (meal number, meal size and eating rate) were recorded by using automated feeders. Feed intake was recorded daily for a minimum of 40 days (mean 41 days), following a 14-day adaptation period. Animals were fed a pelleted hay-based diet, with liveweight measured three times per week. At both ages of measurement, a positive (P &lt; 0.01) linear relationship was established between average daily number of meals and RFI. In these cohorts, as daily number of meals increased, RFI became more positive (less efficient). Meal size (kg DM) was also related to RFI (P &lt; 0.05) when measured at the hogget age, with meal size decreasing with an increasing RFI (less efficient animals had smaller meals). These analyses suggest that sheep feeding behaviour, and in particular daily meal number, is associated with feed efficiency.

The influence of meal size on prey DNA detectability in piscivorous birds

Molecular methods allow noninvasive assessment of vertebrate predator–prey systems at high taxonomic resolution by examining dietary samples such as faeces and pellets. To facilitate the interpretation of field‐derived data, feeding trials, investigating the impacts of biological, methodological and environmental factors on prey DNA detection, have been conducted. The effect of meal size, however, has not yet been explicitly considered for vertebrate consumers. Moreover, different noninvasively obtained sample types remain to be compared in such experiments. Here, we present a feeding trial on abundant piscivorous birds, Great Cormorants (Phalacrocorax carbo), to assess meal size effects on postfeeding prey DNA detection success. Faeces and pellets were sampled twice a day after the feed of large (350–540 g), medium (190–345 g) and small (15–170 g) fish meals contributing either a large (>79%) or small (<38%) share to the daily consumption. Samples were examined for prey DNA and fish hard parts. Molecular analysis of faeces revealed that both large meal size and share had a significantly positive effect on prey DNA detection rate postfeeding. Furthermore, large meals were detectable for a significantly longer time span with a detection limit at ~76 hr and a 50% detection probability at ~32 hr postfeeding. In pellets, molecular methods reliably identified the meal consumed the previous day, which was not possible via morphological analysis or when examining individual faeces. The less reliable prey DNA detection of small meals or meal shares in faeces signifies the importance of large numbers of dietary samples to obtain reliable trophic data.

Appetitive traits and food intake patterns in early life

Background: High food responsiveness (FR) and low satiety responsiveness (SR) are 2 appetitive traits that have been associated longitudinally with risk of excessive weight gain; however, to our knowledge, no studies have examined the associations between these traits and eating patterns in daily life in young children.Objective: We tested the hypothesis that higher FR is independently associated with a higher meal frequency and that lower SR is associated with a larger meal size.Design: Data were from 1102 families (2203 children) from the Gemini twin birth cohort. Appetite was assessed with the use of the Child Eating Behavior Questionnaire when the children were 16 mo old (mean ± SD: 15.73 ± 1.08 mo old), and meal frequency (eating occasions per day) and meal size (kilojoules per eating occasion) were determined from 3-d diet diaries completed by parents when the children were 21 mo old (mean ± SD: 20.65 ± 1.10 mo old). Complex samples general linear models were used to explore cross-sectional associations between appetitive traits and meal variables.Results: After adjustment for the covariates gestational age, birth weight, sex, difference in age at diet-diary completion, and appetite measurement, higher FR was associated with more-frequent meals (B ± SE: 0.13 ± 0.04; P = 0.001) but not with meal size (P = 0.41), and lower SR was associated with a larger meal size (B ± SE: −47.61 ± 8.79; P < 0.001) but not with meal frequency (P = 0.15).Conclusions: FR and SR predict different eating variables with more food-responsive children eating more frequently, whereas less–satiety-responsive children eat more food on each eating occasion. Different strategies may be required to reduce the potential effects of FR and SR on weight gain.

Sasang types may differ in eating rate, meal size, and regular appetite: a systematic literature review.

Eating behaviours may be implicated in the increasing prevalence of obesity and metabolic disorders. The Sasang typology, a unique form of traditional Korean medicine, classifies individuals into four constitutional types that differ in a distinctive complex of external manifestations and innate natures, including eating behaviours. Our aim is to portray a picture of the distinguishing characteristics of eating behaviours across Sasang types and to provide suggestions for future studies. Six Korean and one English database were searched to acquire relevant articles. Ten peer-reviewed relevant research articles were found. The extracted data were categorised into the domains of i) food preferences; ii) eating rate; iii) eating initiation and termination; iv) meal size; v) regularity of eating; vi) regular appetite; vii) eating disorders; and viii) psychological factors. Eating rate and meal size were the issues of most concern that more frequently were different among Sasang types. The TaeEum type seemed to have obesity-linked eating behaviours, including a rapid eating rate, large meal sizes, and a strong appetite, whereas those attitudes seemed to be in contrast with those of the SoEum type. The SoYang type shared similarities with both the TaeEum and SoEum types. Future studies should be conducted with more reliable, objective, and quantitative assessment tools such as the Three Eating Factor Questionnaire or the Dutch Eating Behaviour Questionnaire.

Feeding Chromonaela odorata during pregnancy to goat dams affects acceptance of this feedstuff by their offspring

We investigated the effect of Chromonaela odorata ingestion by goat dams during pregnancy on intake of C. odorata by their kids. Alteration of prenatal feed preference may be used to increase feed intake of novel feeds and the transit from outdoor to indoor goat farming in Vietnam. Ten female goats were synchronized, inseminated and divided randomly into 2 equal groups. The experimental group was offered 50g of sun dried C. odorata leave meal (COLM) along with a basal diet from day 45 to 135 of pregnancy while the control group was offered only the basal diet during this period. After weaning (3mo), one kid from each goat dam in both groups was randomly selected and housed in individual cages. After a 9.5h fast, each kid was offered 50g of COLM daily at 8:30 am for 30min for 4 weeks. Feeding activities were monitored with a video camera system. We determined mean COLM intake and indices of feed acceptance including latency to eat, number of visits without intake, meal frequency, eating bout length, eating time, intake rate, meal size and chewing time for each kid.Intake of COLM by goat kids born to dams fed COLM was significantly higher over the 4 weeks compared to goat kids born to dams not fed COLM (11.32±3.60g vs. 6.09±1.91g, P<0.028). This difference was more pronounced during weeks 3 and 4 than weeks 1 and 2. Goat kids from mothers fed COLM had a shorter latency to eat, a larger meal size and a longer chewing time than kids from mothers not fed COLM during pregnancy. We conclude that in utero transmission of feeding preference occurred from does to their offspring.

Protein-induced weight increase of the gastrointestinal tract of locusts improves net nutrient uptake via larger meals rather than more efficient nutrient absorption

Increasing the tissue biomass and/or volume of the gastrointestinal tract (GIT) is commonly seen when animals feed on poor-quality diets. This increase can simply permit larger meal sizes, but may also rebalance nutritionally imbalanced ingesta by allowing selective absorption of limiting nutrients. In an insect herbivore, the migratory locust, a synthetic diet with a high ratio of protein to carbohydrate was found to induce mass enhancement of the GIT. When normalised for sex and overall body size, increases to the mass of the foregut and midgut caeca resulted in higher absorption (20-30%) of both protein and carbohydrate when subsequently feeding on three chemically and structurally different grasses. Greater net absorption of macronutrients occurred because these locusts ate larger meals that transited at the same time and with the same digestive efficiency as locusts in which the GIT was not enlarged. Thus, plasticity of the GIT did not improve nutritional homeostasis, but increased the rate of nutrient uptake.

Appetite Responds To Gastrointestinal Events While Ghrelin, Leptin, And Insulin Track Changes In Energy Availability

PURPOSE: Appetite is suppressed by exercise but increased by reduced meal size. Appetite relationship to changes in concentrations of its putative controllers ghrelin, leptin, and insulin is unclear. To determine whether appetite, ghrelin, leptin, insulin and digestive peptide GIP respond to changes in processing of food or to energy availability during rest and exercise. METHODS: A crossover study providing trials differing in meal size, exercise energy expenditure, and intravenous nutrient replacement (TPN). Participants were ten healthy postmenopausal women 60 years old with mean BMI of 26 kg/m2. A small 418 KJ morning meal in Rest and Rest-TPN trials and a large 2090 KJ meal in Sed, EX, and EX-TPN trials. Exercise expended 2273 and 2361 KJ, respectively, in EX and EX-TPN trials. TPN replaced 1521 KJ in Rest and 1538 KJ in Rest-TPN trials. Changes in hunger and fullness, mid-day ad-libitum food consumption, and concentrations of ghrelin, leptin, insulin, GIP and metabolic fuels. RESULTS: Large meal size reduced appetite and increased GIP and insulin at rest, but TPN had no effect. Exercise reduced hunger and increased fullness. Appetite was unaffected by TPN. Changes in energy availability due to exercise and TPN affected plasma ghrelin, ghrelin/leptin ratio and insulin but not the appetite, GIP or ad libitum meal size. CONCLUSIONS: Appetite was affected by orogastrointestinal events, while changes in ghrelin, leptin, and insulin responded to changes in energy availability.

Relationship between feeding behaviour and feed intake of dairy cows depending on their parity and milk yield

To investigate the relationship between the parameters of feeding behaviour and feed intake, 70 lactating dairy cows (23 primiparous and 47 multiparous) were monitored from the 2nd to 15th week of lactation. Data were collected by using an automatic feeder and electronic identification of individual cows from 10 July 2005 to 16 January 2006. The resulting data of the cows in primiparous and multiparous condition were categorised into groups based on the mean of their milk yield over the first 15 weeks of lactation: primiparous cows with below-average milk yield (LP) and above-average milk yield (HP) with an average of 28.44 and 34.31 kg energy-corrected milk (ECM) per day, respectively, and multiparous cows with below-average milk yield (LM) and above-average milk yield (HM) with an average of 38.70 and 44.49 kg ECM per day, respectively. The parameters of feeding behaviour were calculated based on the estimated meal criterion from pooled data. Parity, level of milk yield, and day had significant effects on some of characteristics of feeding behaviour and feed intake parameters. There was no significant difference in meal duration either between primiparous and multiparous cows or between LP and HP. However, a significant difference between LM and HM was observed. Cows in HM had shorter feeding times but a larger meal size, higher DMI, and feeding rate. Moreover, these cows displayed a stronger correlation between meal duration, daily mealtime and daily feed intake ( r = 0.37 and 0.50, P < 0.001, respectively) than any other cow or group of cows of the study. Meal duration, daily mealtime, meal size and daily DMI increased on average about 32%, 20%, 35%, and 22% respectively, considering all milk yield groups from the 2nd to 15th week of lactation.

Effect of Different Types of Food on Metabolic Rate in Rats

The present study was designed to investigate the effect of ingestion of 2 different classes of the three macronutrients-carbohydrates, proteins and fats on the metabolic rate, and to compare the degree at which they stimulate the metabolic rate. Twelve Sprague Dawley rats weighing 140-200 gm were divided into three groups. Carbohydrate fed group, Protein fed group and Fat fed group. Each group of rat served as its own control. The rats were allowed free access to the cooked food for 24 hours and stayed for 12 hours on each occasion before the metabolic rate was measured. The method used in measuring the metabolic rate was by indirect calorimetry. Results showed that the different food- carbohydrate, protein and fat ingestion each, caused a significant increase (p0.05) was observed when the metabolic rate of the two foods in each of the groups was compared. . Also it was concluded that a large meal size would stimulate the metabolic rate to the same extent as a small meal size provided the minimum requirement is met. Keywords: Metabolic rate, Carbohydrate Protein, Fat, Food.NQJHM Vol. 16 (2) 2006: pp. 45-48

Food motivated behavior of melanocortin-4 receptor knockout mice under a progressive ratio schedule

Melanocortin-4 receptor knockout (MC4RKO) mice are hyperphagic and develop obesity under free feeding conditions. We reported previously that MC4RKO mice did not maintain hyperphagia and as a result lost weight when required to press a lever to obtain food on a fixed ratio procurement schedule. To assess the generality of this result, we tested MC4RKO mice and their heterozygous and wild type littermates using progressive ratio (PR) schedules that are believed to be sensitive indicators of motivation. Mice lived in operant chambers and obtained all of their food (20 mg pellets) via lever press responding. Food was available according to a PR schedule so that within a meal, food became progressively more costly, and we expected this would provide a stringent test of mechanisms controlling meal size. The schedule reset after either 3 or 20 min of no responding, so defining meals, and the highest ratio completed before the reset was defined as the breakpoint. The average daily number of meals was lower and mean size of meals was higher at the 20 compared with the 3 min reset condition. Mean daily food intake did not differ between the two reset criteria but did differ as a function of genotype, with MC4RKO mice eating about 25% more than heterozygous or wild type mice. Hyperphagia in the MC4RKO mice was characterized primarily by larger meals (higher breakpoints) and they emitted about twice as many responses as wild type mice. Thus, using a PR schedule, MC4RKO mice exhibit hyperphagia, and show a high level of motivation to support large meal sizes.

Effects of dietary nonstructural carbohydrates and protein sources on feeding behavior of tethered heifers fed high-concentrate diets1

To describe the feeding behavior of growing heifers fed high-concentrate diets with different sources of protein and nonstructural carbohydrates, and to explain the ruminal fermentation pattern, 4 ruminally fistulated Holstein heifers (BW = 132.3 +/- 1.61 kg) were assigned to a 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Two non-structural carbohydrate sources (barley and corn) and 2 protein sources [soybean meal (SBM) and sunflower meal (SFM)] that differ in their rate and extent of ruminal degradation were combined, resulting in a synchronized, rapid fermentation diet (barley-SFM), a synchronized, slow fermentation diet (corn-SBM), and 2 unsynchronized diets consisting of a rapidly and a slowly fermenting component (barley-SBM and corn-SFM). The corn-SFM diet resulted in a lower frequency of feeding (P < or = 0.05), longer meal length (P < or = 0.043), and larger meal size (P < or = 0.037) than the other 3 diets. Dietary treatment had no effect (P > or = 0.09) on the daily percentages of posture and behaviors. In general, heifers spent 9.97 +/- 0.83% of the day eating, 2.11 +/- 0.42% drinking, 25.13 +/- 1.36% ruminating, 16.97 +/- 1.42% in other activities such as social behavior and self-grooming, and the rest of the day (45.82 +/- 2.55%) resting or doing no chewing activities. Eating, drinking, and social behaviors were performed while standing (P < or = 0.01), whereas resting and ruminating occurred mainly while lying (P = 0.001). Eating took place mainly in the first 4 h after feeding (P = 0.001), whereas ruminating occurred mainly at night (P = 0.001). When chewing activities (eating and ruminating) were expressed per kilogram of DM or NDF from roughage intake, more time (P = 0.004) was spent chewing per kilogram of DMI for barley-based diets, and per kilogram of NDF from roughage intake for barley- (P = 0.01) and SFM- (P = 0.002) based diets. Tethered heifers fed the more fermentable and rapidly synchronized diet (barley-SFM) reduced intake and increased chewing time. With these high-concentrate diets, time spent chewing was inversely related to roughage intake.