Voluntary Food Intake Research Articles

Thein vitrogas production characteristics of whole roughageversusextracted neutral-detergent fibre and their implications for analysing the fermentation of cell solubles by a differential approach

The separation of forages into a soluble fraction like cell contents and into an insoluble matrix like cell walls is an initial step in forage evaluation. Further analysis can be applied to study fermentation characteristics of soluble and insoluble fractions. Unfortunately, most laboratoryin vitrotechniques quantify incubation insoluble residues and are therefore inappropriate for the examination of food solubles.In vitrogas methods (for example Menkeet al., 1979) reflect the production of short chain fatty acids (SCFA) and are therefore free of the disadvantages associated with gravimetric methods. However, it was recently pointed out that an inverse relationship may exist between SCFA production and microbial biomass yield (for review see Blümmelet al., 1997a). These authors suggested combiningin vitrogas measurements with the quantification of substrate concomitantly degraded to calculate a partitioning factor (PF). This factor reflects the substrate-dependent variation in SCFA production and microbial biomass yield; the factor (PF) was shown to be valuable in voluntary food intake (DMI) predictions (Blümmelet al., 1997b). In the work presented here, the rate and extent of fermentation of whole roughages and extracted neutral-detergent fibres (NDF) of 54 roughages were examined in an in vitro gas test. The dry-matter degradability of extracted NDF was also quantified and the partitioning factor for NDF (PFNDF) was determined. The relevance of these findings for the analysis of extracted NDF and cell solubles is discussed and their implications for the prediction of DMI of roughages by gas tests are addressed.

Influence of the pattern of nutrient release from grass silage and the effect of supplementation on the voluntary food intake of growing lambs

Grass silage is an important feed for ruminants but it is well established that the voluntary food intake (VFI) is less than that of the same crop fed fresh or dry (Harris and Raymond, 1963). This effect has been associated with factors such as the products of ensiling as well as the asynchrony of nutrient release in the rumen. The objectives of the current experiment were to investigate whether the pattern of nutrient release in grass silage is a major factor contributing to its low intake and whether altering the pattern of nutrient release through supplementation would alter hourly and daily intake.

Influence of the pattern of nutrient release from grass silage and the effect of supplementation on the voluntary food intake of growing lambs

Grass silage is an important feed for ruminants but it is well established that the voluntary food intake (VFI) is less than that of the same crop fed fresh or dry (Harris and Raymond, 1963). This effect has been associated with factors such as the products of ensiling as well as the asynchrony of nutrient release in the rumen. The objectives of the current experiment were to investigate whether the pattern of nutrient release in grass silage is a major factor contributing to its low intake and whether altering the pattern of nutrient release through supplementation would alter hourly and daily intake.

Short Term Intake Rate (STIR) as a method of ranking the intake potential of forage mixtures by dairy cows

Studies conducted by Moseley and Manendez (1989) and Gill and Romney (1994) have indicated a good correlation between potential intake rate and voluntary food intake for certain feedstuffs. Therefore development of a simple technique to assess intake rate could enable rapid assessment of feed acceptability. This experiment examined what will be termed Short Term Intake Rate (STIR) as a method of ranking forage mixtures in terms of intake potential.Five individually fed multiparous Fresian Holstein dairy cows were offered five silage based diets ad libitum daily for five days in a latin square design. The diets consisted of grass silage (A), or grass silage and maize silage in a 1:3 DM ratio (B, C, D and E). The DM content of the grass silage (A) was 279 g DM/kg, and the target DM content of the maize silage used in diets B, C, D and E was 230, 280, 300 and 380 g DM/kg respectively. The DM content of the forage mixtures B, C, D and E were 278, 302, 318 and 373 g DM/kg.

Short Term Intake Rate (STIR) as a method of ranking the intake potential of forage mixtures by dairy cows

Studies conducted by Moseley and Manendez (1989) and Gill and Romney (1994) have indicated a good correlation between potential intake rate and voluntary food intake for certain feedstuffs. Therefore development of a simple technique to assess intake rate could enable rapid assessment of feed acceptability. This experiment examined what will be termed Short Term Intake Rate (STIR) as a method of ranking forage mixtures in terms of intake potential.Five individually fed multiparous Fresian Holstein dairy cows were offered five silage based diets ad libitum daily for five days in a latin square design. The diets consisted of grass silage (A), or grass silage and maize silage in a 1:3 DM ratio (B, C, D and E). The DM content of the grass silage (A) was 279 g DM/kg, and the target DM content of the maize silage used in diets B, C, D and E was 230, 280, 300 and 380 g DM/kg respectively. The DM content of the forage mixtures B, C, D and E were 278, 302, 318 and 373 g DM/kg.

Short-term feeding behaviour of dairy cows relative to food composition and stage of lactation

Short-term feeding behaviour (STFB) has been used to elucidate the physiological mechanisms which control eating. It has been proposed as a means by which to predict voluntary food intake, and could be used to quantify behavioural characteristics of the cow. The first step in assessing the usefulness of STFB for these purposes is to identify the major factors which influence STFB. The aim of the study reported here was to evaluate, in dairy cows, the differences in STFB resulting from two different foods, the effect of stage of lactation on STFB, and the effect on STFB of changing from one food to another.

Vertebrate Herbivory on Eucalyptus —Identification of Specific Feeding Deterrents for Common Ringtail Possums ( Pseudocheirus peregrinus ) by Bioassay-Guided Fractionation of Eucalyptus ovata Foliage

Factors determining the acceptance of Eucalyptus ovata foliage by common ringtail possums (Pseudocheirus peregrinus) were studied. Bioassay-guided fractionation was used with foliage from both browser-susceptible and browser-resistant trees to identify the chemical components underlying the resistance. In foliage from browser-resistant trees, the deterrent principles were contained in the base-soluble fraction of the chloroform extract. Further fractionation of this material yielded polar and nonpolar fractions that contained acylphloroglucinol derivatives, and from the polar fraction we isolated macrocarpal G. Addition of this compound to an artificial diet at a concentration of 2.1% of dry matter resulted in a 90% reduction of voluntary food intake compared with solvent-treated controls. This is the first time that a specific compound in Eucalyptus has been shown to inhibit feeding of any marsupial folivore.

A history ofin vitrotechniques

AbstractRegressions relating in vivo digestibility to chemical composition of the food have residual standard deviations that are unacceptably high. The development of the two-stage in vitro technique inoculated with rumen liquor (Tilley and Terry, 1963) allowed dry-matter digestibility to be predicted with greater accuracy. This success was followed by a series of developments which replaced rumen liquor with inoculum produced from fresh or preserved faeces collected from sheep or cattle. Other methods used inoculum from a continuous fermentation containing rumen micro-organisms and enzymes produced by fungi. Another modification was to use gas production as a measure of in vitro digestion. The range of nutritional problems that could be measured by in vitro techniques was extended to include the estimation of voluntary food intake and protein degradation. All these in vitro techniques require standardization using food samples that have previously been analysed in vitro or offered as the sole diet to animals. The relative merits of these two calibration methods are discussed. Special facilities are required for storing and distributing these standard foods.

Short-term feeding behaviour of dairy cows relative to food composition and stage of lactation

Short-term feeding behaviour (STFB) has been used to elucidate the physiological mechanisms which control eating. It has been proposed as a means by which to predict voluntary food intake, and could be used to quantify behavioural characteristics of the cow. The first step in assessing the usefulness of STFB for these purposes is to identify the major factors which influence STFB. The aim of the study reported here was to evaluate, in dairy cows, the differences in STFB resulting from two different foods, the effect of stage of lactation on STFB, and the effect on STFB of changing from one food to another.

Effect of acute histamine and pentagastrin on voluntary food intake in growing chickens

To study the action of histamine (a potent secretagogue in mammals and chickens) on food intake, 5-week-old male chickens ( n = 7) were injected intraperitoneally with 0, 500 or 1000 μg/kg body weight of histamine. Food intake was measured at 6, 15, 30, 45, 60, 90 and 120 min after injection of histamine. Water intake was measured at 15, 30, 45, 60, 90 and 120 min after injection of histamine. A second experiment was carried out to see if another potent secretagogue, pentagastrin, exhibits a similar effect on food intake in chickens. In the first trial a group of chickens ( n = 8) received 0, 25 or 50 μg/kg body weight of pentagastrin intraperitoneally. Food and water intake were measured at 15, 30, 45, 60, 90 and 120 min after injection of pentagastrin. In the second trial, another group ( n = 8) received higher doses of pentagastrin (0, 100 or 200 μg/kg body weight) under similar conditions as above but only food intake was measured. In all cases the animals were starved for 16 h before injection of drugs. The results obtained were different for the two secretagogues utilized. Whereas histamine decreased consumption ( P < 0.05), pentagastrin did not show a similar response either in low or high doses. No differences were observed for water intake in any cases. These results suggest that histamine, but not pentagastrin, plays an inhibitory effect on the regulation of food intake in chickens. From these findings, it could be assumed that histamine's secretory property is not the primary mechanism by which histamine inhibits eating. Since peripherally administered histamine decreases food intake in chickens, the H1, H2 or H3 receptors could very possibly be involved in such response and this requires further research.

Nutritional efficacy of a spermidine supplemented diet.

Polyamines (PA) are ubiquitous cell components essential for growth. Dietary PAs are directed preferentially to tissues and organs that have been stimulated to grow by metabolic signals. Nutritional efficacy and growth potential of an oral PA supplement, spermidine (SD), was examined in growing rats. A group of 24-male Sprague-Dawley rats (200-220 g) was adapted to our vivarium conditions for 3 d, then fed ad libitum continuously for 14 d. During feeding they received either a basal diet (n = 8) or a test diet containing the basal diet with 0.05% SD (test diet 1, n = 8) or 0.10% SD (test diet 2, n = 8). This dose of SD corresponds to an intake of 54 and 108 mumol of SD per rat per day. At the end of 14 d of feeding, the animals were sacrificed and plasma, cerebral spinal fluid (CSF) and tissues (muscle, brain, and liver) were harvested for amino acid analysis. Voluntary food intake, body weight gain, and nitrogen excretion and balance were significantly decreased in test diet 2 fed rats compared to test diet 1. The opposing trends in the accumulation/depletion of free amino acids (AA) in muscle and plasma suggests that the exogenous supply of SD blocks the transport of amino acids, as well as PAs from the cells, since AA and PA share the same transport systems. A trend toward decreased weight gain and feeding efficiency was observed when high concentrations of SD were fed. It was concluded that feeding of SD at moderate intake is not toxic and does not retard growth. Oral administration of a smaller dose (<0.05%) of SD may promote further growth. The optimal level of SD dietary supplementation has thus yet to be established.

Supplementation with Gliricidia sepium and Leucaena leucocephala on voluntary food intake, digestibility, rumen fermentation and live weight of crossbred steers offered Zea mays stover

Twenty intact and five fistulated crossbred steers were used in two experiments to examine the effect of supplementing maize stover with Gliricidia sepium or Leucaena leucocephala forage on intake, rumen fermentation, microbial protein supply and live weight changes. The basal diet plus 1 kg maize bran was offered alone or supplemented with 7.5, 15, 22.5 or 30 g DM/kg W 0.75 of gliricidia (experiment 1), and with either 15 or 30 g DM/kg W 0.75 of gliricidia or leucaena forage (experiment 2). Supplementation increased total dry matter intake (TDMI) ( P < 0.001). DMI of stover was depressed ( P < 0.001) in experiment 1 from 2.1 to 1.3 kg/day, but increased at the lower levels of supplementation in experiment 2. Diet digestibility was only significantly increased in experiment 2. Supplementation increased the rumen ammonia from 53 to 106 mg/l and from 31 to 111 mg/l in experiment 1 and 2 respectively, and tended to improve the degradation characteristics of the basal diet. The efficiency of microbial N supply ranged between 21.0 and 27.7 g N/kg DOMR. The live weight gains from supplementation were greater, and the responses to gliricidia and leucaena did not differ significantly. It is concluded that the supplementation improved dry matter intake and live-weight gains, and that Gliricidia sepium could be an alternative supplement to Leucaena leucocephala .

Feeding Behaviour and Food Utilisation in Tilapia, Oreochromis Niloticus: Effect of Sex Ratio and Relationship With the Endocrine Status

Toguyeni, A., B. Fauconneau, T. Boujard, A. Fostier, E. R. Kuhn, K. A. Mol and J. F. Baroiller. Feeding behaviour and food utilisation in Tilapia, Orechromis niloticus: Effects of sex ratio and relationship with the endocrine status. Physiol Behav 62(2) 273–279, 1997.—The feeding behaviour of male monosex, female monosex, and mixed groups of Oreochromis niloticus was studied under conditions of self-feeding. Feeding activity was observed almost exclusively during the light period. The food intake pattern was similar whatever the sex ratio, and voluntary food intake (VFI) appeared lower in the male monosex groups than in the others. Male monosex groups displayed higher specific growth rates (SGR) and a lower food conversion ratio than female monosex and mixed groups. The SGR of males was higher in the monosex than in the mixed groups, whereas females of mixed and monosex groups displayed no significant difference in SGR. The efficiency of food utilisation was also analysed: nutrient retention ratios were higher in male monosex than in female monosex and mixed groups. Males displayed a distinctly higher metabolic capacity. Differences in sex-related hormones (11 ketotestosterone = 11-KT, 17 β-Oestradiol = 17 β- E2) and a metabolic hormone (triiodothyronine = T3) were observed between males and females. The hypothesis of an involvement of these hormones in the higher metabolic capacity of males is discussed. The observed differences in feeding behaviour between the different groups also suggest an effect of social interactions on the efficiency of food conversion and thus on the differential growth of males and females.

The body weight of the dairy cow II. Modeling individual voluntary food intake based on body weight and milk production

Voluntary food intake of the dairy cow is an important variable in the dairy herd operation, We are unable to measure it individually in the conventional dairy operation when cows are kept in groups or grazing. This prevents using voluntary food intake as a parameter in the management decision-making process for the individual cow. Existing formulas that calculate dry matter intake (DMI) from ration and performance variables (see Mertens 1985), are not applicable for estimating DMI of an individual cow for on-line decision making such as adjusting ration density by computerized self feeders (Maltz et al. 1991, 1992Maltz and Metz 1994). In this work we calculated the dairy cows' DMI on a daily and individual basis, employing a non-conventional approach involving only body weight (BW) and milk yield (MY). These two variables are measurable on-line daily for individual cows. Daily MY, BW and DMI data of 24 cows during 147 days of lactation were obtained from the IMAG-DLO research farm in Duiven, the Netherlands, as described by Devir et al. (1996). A multivariable non-linear regression model was developed (Makidridakis et al. 1983) using MY, BW and interrelations between them as independent variables and DMI as the dependent variable. The steps of selecting variables and model were: (1) Visual analysis of plotted daily BW, MY and DMI data of all cows separately; conclusions were withdrawn regarding similar patterns in all cows. (b) Statistical determination of the variables' daily fluctuations. (c) Factors' selection and filtration using Cross-Correlation analysis. (d) Choosing and evaluating the model. (e) Running the model with statistical analysis of the filtered factors, using SPSS statistical software, especially the function Cross-Correlation and Step-Wise software. The model wad calibrated on 8, 12, 16, and 20 randomly selected cows and its validity was checked each time on the rest of the cows. No significant improvement in DMI prediction was found beyond 16 cows' calibration. The model predicted DMI efficiently in terms of actual values, timing of maximal DMI and its patters (Fig. 2). It was concluded that the selected variables are strongly correlated with DMI and that Polynomial Fitting of daily model calculated DMI (Fig. 3) enables to use it as a decision-making aid in calculating individual cows ration energy density (Maltz and Metz 1994). More model testing is needed regarding different rations and cows before this model can be used as a decision-making aid.

The Effects of Glucose or Lipid Infused Intravenously or Intragastrically on Voluntary Food Intake in the Rat

Burggraf, K. K., A. E. Willing and H. S. Koopmans. The effects of glucose or lipid infused intravenously or intragastrically on voluntary food intake in the rat. Physiol Behav 61(6) 787–793, 1997.—Glucose or lipid was infused intravenously (IV) or intragastrically (IG) 30 min before and also during the 17 h when rats were fed both a high-carbohydrate diet and a high-fat diet. Three-day infusions of 28.1 kcal of glucose reduced daily food intake by 19.7 ± 1.9 kcal/day, representing an oral intake reduction equivalent to 70% of each calorie infused. Infusions of 28.1 kcal of lipid reduced baseline food intake by 11.2 ± 2.7 kcal/day or 40% of each calorie infused ( p < 0.0005). Furthermore, infusions of nutrient IG reduced baseline food intake by 17.6 ± 2.1 kcal/day or 63% of each calorie infused, and infusions of nutrient IV reduced baseline food intake by 13.7 ± 2.6 kcal/day or 49% of each calorie infused ( p < 0.05). Also, glucose infusions (1.0 kcal/40 min) reduced 10-min food intake from saline baseline levels by 1.1 ± 0.5 kcal, but lipid infusions had no effect. Infused glucose is more effective than lipid in inhibiting short-term intake, daily food intake, and intake of high-carbohydrate diet, and IG infusion is more effective than IV infusion in inhibiting daily food intake.

The effect of previous body condition on appetite and associated insulin profiles in sheep

AbstractThe effect of previous level of body condition on appetite was studied in 47 housed Scottish Blackface ewes, which had been either thin (L: mean condition score 2·15, s.e. 0·030; no. = 24) or fat (H: mean condition score 3·15, s.e. 0·056; no. = 23) 8 weeks before the start of the experiment. The mean daily voluntary food intake (VFI) of a dried grass pellet diet was higher for the L than for the H ewes (2176 v. 1727 g dry matter per day; P &lt; 0·001) during the first 6 weeks of the experiment (period 1). Over this time, live weights increased from 60·5 or 69·9 (s.e.d. 1·68) to 68·4 or 75·6 (s.e.d. 1·94) and condition scores increased from 2·84 or 3·16 (s.e.d. 0·057) to 3·13 or 3·38 (s.e.d. 0·071) for the L and H ewes respectively.At the end of the 6-week period, plasma insulin concentrations were measured in 10 ewes from each treatment (mean condition scores 3·15 (L) and 3·27 (H) (s.e.d. 0·091)) when fed both ad libitum and at a fixed level of 1200 g/day for consecutive 11-day periods (period 2). Mean VFI was higher for the L than for the H ewes (2191 v. 1661 g dry matter per day; P &lt; 0·05) over the period of ad libitum feeding. There was no effect of feeding level (ad libitum v. 1200 g/day) on mean plasma insulin concentrations, but the mean basal plasma insulin concentration was higher in the H than in the L ewes (43·0 v. 29·0 mil per 1; P &lt; 0·05). Fifteen minutes after the ingestion of a single 400 g meal, the plasma insulin concentration in the H ewes was higher than the mean prefeeding value (63·3 v. 41·7 mil per I; P&lt;0·05) but there was no corresponding increase in the L ewes. The plasma insulin concentration 15 min after the intravenous administration of a single dose of 0·25 U per kg live weight of insulin ivas higher in the H than in the L ewes (1723 v. 1031 mil per 1; P &lt; 0·01) but there were no differences between treatments in plasma glucose concentrations following insulin administration.It was concluded that previous body condition can affect contemporary VFI and this effect may be mediated by plasma insulin concentrations providing a long-term feedback signal to the brain. Keywords: body condition, food intake, insulin, sheep.

The influence of heat production on voluntary food intake in growing pigs given protein-deficient diets

AbstractNinety-six entire male Large White XLandrace pigs were assigned at 13 kg to one of six dietary crude protein (P) treatments (230 g/kg (P1), 201 g/kg (P2), 178 g/kg (P3), 151 g/kg (P4), 125 g/kg (P5), 93 g/kg (P6)) and one of four temperatures (T) (no. = 4) (18°C, 22°C, 26°C, 30°C), and were given food ad libitum until slaughter weight of 30 kg. At all temperatures gut fill was a constant proportion of food intake (Fl) (1·56) but this ratio varied with different protein concentrations. Food intake increased with decreasing temperature and with decreasing protein content to a maximum rate on P4 (1·347 kg) whereafter FI declined. There was a linear decrease in average daily gain (ADG) with decreasing protein content while temperature had a significant curvilinear effect on ADG and food conversion ratio (FCR) with maximum ADG (0·680 kg/day) at 26°C. Body protein content decreased as the dietary protein concentration declined below P3 and there was a corresponding increase in lipid content. Temperature had no effect on body protein content but had a significant effect on lipid content. Similar trends occurred in the rate of protein (PR) and lipid (LR) retention with maximum PR (117·1 g/day) attained on PI, P2 and P3. Protein and temperature had a significant effect on total heat loss (THL). Maximum THL occurred in the protein treatment that resulted in pigs consuming maximum FI. The efficiency of protein utilization increased with increasing temperature but the response was dependent on the protein supply. It is concluded that on low protein diets pigs increase their Fl to maintain potential protein growth until a point is reached where the animal can no longer compensate and FI will decline. The extent of the compensation will depend on the amount of heat the animal can lose which in turn is dependent on the environmental temperature.

Protein malnutrition increases plasma adrenocorticotropin and anterior pituitary proopiomelanocortin messenger ribonucleic acid in the rat.

The mechanism by which protein malnutrition increases circulating glucocorticoids is unclear. To determine whether ACTH synthesis and secretion also increase in protein malnutrition, rats were sham adrenalectomized or adrenalectomized and replaced with varying amounts of corticosterone before dietary protein deprivation. Pair-fed rats served as controls for reduced voluntary food intake in protein-deprived rats. Dietary protein deficiency, but not pair-feeding, increased resting plasma corticosterone in sham-adrenalectomized rats. Restraint-induced ACTH secretion was not inhibited by the increased basal corticosterone levels in protein-deficient rats. When increases in corticosterone were eliminated by adrenalectomy or controlled by adrenalectomy with low level corticosterone replacement, increases in resting plasma ACTH and anterior pituitary POMC messenger RNA expression occurred with protein deprivation that could be statistically discriminated by regression analysis from changes due to caloric restriction (pair-feeding) and overt glucocorticoid feedback resistance. We conclude that protein malnutrition increases pituitary-adrenocortical activity at least in part by specifically increasing the drive for ACTH synthesis and secretion.

The patho-physiology ofTrypanosoma congolensein Scottish Blackface sheep: influence of diet on digestive function

AbstractThe influence of types of roughage, barley straw (diet B) versus lucerne hay (diet L), on the patho-physiology of a T. congolense infection was compared in eight pairs of Scottish Blackface male twin lambs. One animal of each twin pair was infected and the other used as a pair-fed control. Voluntary food intake, body weight, digestive function, various blood haematological and biochemical measurements were made.Voluntary organic matter intake decreased significantly after the T. congolense infection, the decrease being greater in the diet L group than in the diet B group lambs (P &lt; 0·01). The apparent digestibility coefficients of crude protein and organic matter were significantly lower in the infected lambs (P &lt; 0·01). Mean retention time of the roughage through the digestive tract in the animals given barley straw was significantly longer (P &lt; 0·05) due to a lower rumen outflow rate constant (P &lt; 0·01). Infection resulted in longer mean retention times (P &lt; 0·01).Packed cell volume (PCV) was significantly lower before infection in the animals given diet B (P &lt; 0·01). After infection, diet (P &lt; 0·01) and infection (P &lt; 0·01) had an additive effect on PCV. The anaemia was both macrocytic (P &lt; 0·05) and hypochromic (P &lt; 0·01).Diet B resulted in higher plasma cholesterol (P &lt; 0·05), but lower plasma urea (P &lt; 0·01) and albumin (P &lt; 0·01) concentrations before infection than diet L. The T. congolense infection significantly lowered plasma cholesterol (P &lt; 0·01) and increased plasma urea (P &lt; 0·01) concentrations compared with the uninfected controls. Plasma albumin concentrations decreased, but were more affected by nutrition (P &lt; 0·01) than by infection (P &lt; 0·05).It ivas concluded that the patho-physiological effects of the T. congolense infection in the Scottish Blackface lambs were affected by the type of roughage offered, but that these effects were additive rather than interactive to the effects of infection.

CCK is involved in both peripheral and central mechanisms controlling food intake in chickens.

The aim of this work was to study the involvement of cholecystokinin (CCK) in the control of food intake in chickens. The following aspects were studied: 1) the effects of intravenous and intracerebroventricular sulfated octapeptide of CCK (CCK-8s) on voluntary food intake; 2) the effects of two CCK-receptor antagonists. L-365,260 and L-364,718, on food intake; and 3) the ability of such drugs to block the effects of CCK-8s on food intake in the chicken. Intravenous and intracerebroventricular CCK-8s caused a decrease in food intake. Intraperitoneal L-365,260, a CCK-receptor antagonist with low affinity for the two CCK receptors described in the chicken, increases food intake. Intracerebroventricular L-364,718, a drug that has high affinity for the chicken central CCK-receptor type, increased food intake. The effect of intravenous CCK-8s on food intake was not blocked by L-364,718 or L-365,260, whereas that of intracerebroventricular CCK-8s was blocked by intracerebroventricular L-364,718. It is concluded that central endogenous CCK plays a role in the control of food intake, which is dependent on central CCK-receptor type; nevertheless, peripheral CCK also decreases food intake acting on the peripheral CCK-receptor type. The fact that intracerebroventricular L-364,718 is able to increase food intake is related to its high affinity for the central CCK-receptor type of this species. Finally, three different speculations that might explain the fact that intraperitoneal L-365,260 increases food intake are discussed.