Parameters for quantification of hunger in broiler breeders

The commercial restricted feeding programme of broiler breeders has a major negative effect on welfare, as the birds are continuously hungry. Objective parameters of hunger are needed to evaluate new management or feeding systems that may alleviate hunger and thus improve broiler breeder welfare. The aim of this experiment was to develop such parameters. Female broiler breeders (Hybro G), n=10 per treatment, were subjected to different levels of feed restriction and we assumed that we thus induced different levels of hunger. Treatment groups were fed ad libitum and at 90%, 70%, 50%, 35% and 25% of ad libitum. In addition, female broiler breeders that were less intensively selected on growth and food conversion (JA57, n=10 per treatment) were fed ad libitum and at 70% of ad libitum. At 6-7 weeks of age, home pen behaviour, behaviour in the open field and baseline plasma corticosterone, glucose and nonesterified fatty acid (NEFA) concentrations were determined. Thereafter, birds were subjected to the feed intake motivation (FIM) test that measures compensatory feed intake. Linear relationships between the level of restriction and the compensatory feed intake on the first days of the FIM test and the glucose/NEFA ratio were found which indicate that these parameters can be used to quantify the level of hunger. Curvilinear relationships between sitting and standing in the home pen, walking in the open field and level of restriction were found. A third-grade hyperbolic relationship between the level of restriction and the baseline plasma corticosterone concentration was found. Thus, these parameters do not seem to represent a straightforward relation with the level of hunger. Intensive selection on growth and food conversion seems to have affected the behaviour but not the physiological responses to feed restriction, because the JA57 birds responded behaviourally, but not physiologically, different to feed restriction as compared with the Hybro birds.     

The gross morphology of skeletal disease in adult male breeding turkeys

The incidence of skeletal disease has been studied in two groups of male turkeys which were reared and kept as breeding birds. One group was fed ad libitum throughout life whereas the other was reared under dietary restriction to give body weights between 50% and 80% of the ad libitum values, depending on age. Losses during rearing were higher in ad libitum fed birds with lameness the major single cause. The majority of birds were killed at 55 weeks of age. It was noted that before death, more than half of the ad libitum birds were lame and the remainder showed gait abnormalities. By contrast, gait and posture was judged to be normal in many of the birds kept under feed restriction and none was lame. Post mortem dissections revealed a much higher incidence of skeletal disease in birds fed ad libitum. Although these observations suggest that feed restriction may alleviate skeletal disease in male breeding turkeys, it is suggested that such a strategy is of no long term benefit in parent breeding stock.     

Motivation for hay: Effects of a pelleted diet on behavior and physiology of horses

The natural diet of free-ranging horses is grass, which is typically high in fiber and calorically dilute, however diets for high performance domestic horses are often low in fiber and calorically dense. The aim of the study was to determine the motivation of horses for hay when fed a low roughage diet. Their motivation could be used to determine if low roughage diets compromise the welfare of horses. Eight mares were fed two different diets in counterbalanced order: ad libitum orchard grass hay; a complete pelleted feed (pellets). Each trial lasted three weeks, with a one-week transition period between diets. To determine the motivation of horses for fiber they were taught to press a panel to obtain a food reward. The fixed ratio (FR) was increased using a progressive ratio ((1,2,4,7,11…) technique. When fed pellets, the horses worked for a median FR of 1 (Range = 1-497) to attain pellets, and when fed hay, they worked for a median FR of 25.5 (4-497) to attain pellets. When fed hay, the horses worked for a median FR of 0 (0-0) to attain hay, and when fed pellets, they worked for a FR of 13 (2-79) to attain hay. These results indicate a greater motivation for hay, a high fiber diet, when fed a low fiber diet. The horses spent 10 (5-19.4)% of their time during a 24-hour period eating pellets compared to 61.5 (29-76) % of their time eating hay. Horses spent 58% of their time standing when fed the pellets and only 37% of their time standing when fed hay. Searching behavior (i.e. sifting through wood shaving bedding for food particles) took up 11.5 (1.4-32) % of the horse's day when fed pellets, but only 1.2 (0-3.5) % of the daily time budget when fed hay. Horses chew more times when eating a hay diet (43,476 chews/day) than when eating a pellet diet (10,036 chews/day). Fecal pH was lower in horses fed the pelleted diet.     

An investigation into the role of the crop in control of feeding in Japanese quail and domestic fowls

With normal diets, removal of the crop in Japanese quail and domestic fowls caused reductions in mean meal lengths and sizes, and compensatory increases in meal frequencies, only in those (30-40%) birds that had previously eaten larger, less frequent meals. Sham operation had no such effect. Cropectomy had less effect on feeding activity parameters when quail were fed on a diluted (40% cellulose) diet, and had no effect on diurnal patterns of feeding with either undiluted or diluted food (all birds tending to eat more at the end of the day). This may have been because cropectomized birds could store food in the oesophagus in amounts similar to those previously stored in the crop. Cropectomy had no apparent long-term effect on food intake with undiluted diets, but may have suppressed it slightly with diluted food. In intact quail and fowls, with ad lib access to food when killed, crops were often found to be empty with undiluted food, but were rarely so with diluted food. Gizzards also tended to hold more with diluted food, but were never completely empty with any diet. The post-crop oesophagus and proventriculus were empty in nearly all birds. In quail fasted for two hours, then allowed to feed for 20 min and killed at intervals over a further two hours, maximum amounts of undiluted and diluted food in crops and gizzards were generally greater than in ad lib-fed quail. Crops and gizzards emptied faster with diluted than with undiluted food, but no gizzard was completely empty two hours after feeding. The results of these experiments indicate that, with normal diets, meal termination (satiety) during most of the day is associated with partial crop filling in (30-40%) birds that habitually eat larger, less frequent meals, and with varying degrees of gizzard filling in birds with smaller meals. Satiety involves more crop filling in more birds with diluted food, and this may also apply to other factors that cause increased feeding activity. Meal initiation (hunger) may be associated with partial gizzard emptying in all birds. At some stage towards the end of the day there is usually a conditioned change to cumulative filling of the crop with enough food to be processed overnight.     

Supplementation of dietary vitamins,protein and probiotics on semen traits and immunohistochemical study of pituitary hormones in zinc-induced molted broiler breeders

The purpose of this study was to investigate the effect of dietary vitamin E and vitamin C, probiotics mixture and protein level and their combination on semen quality and immunohistochemical study of some pituitary hormones in male broiler breeders. One hundred and eighty male broiler breeders 65 weeks old were divided into six groups by completely randomized design. The birds were subjected to zinc-induced molt by mixing zinc oxide at the rate of 3000 mg/kg in the feed. After molting, one group was fed control diet (CP16%). The other groups were fed vitamin E (100 IU/kg), vitamin C (500 IU/kg), probiotics (50 mg/L of drinking water), protein (CP14%) and combination of these components. These treatments were given for five weeks. After the feeding period, semen samples were taken and analyzed for semen volume, sperm concentration, motility and dead sperm percentage. Pituitary samples were collected from three birds per replicate and were processed for immunohistochemical study. The results of semen quality parameters revealed that semen volume and sperm motility were significantly high in the vitamin E fed group, while the dead sperm percentage decreased significantly in the vitamin C group. The morphometric analysis revealed that compared to other groups, vitamin E caused a significant increase in the size and area of FSH, LH gonadotropes and lactotropes. These results showed that vitamin E alone may play some role in the enhancement of semen quality and growth of gonadotropes and lactotropes.     

Can overeating induce conditioned taste avoidance in previously food restricted rats?

While feeding is rewarding, the feeling of satiation has been theorized to have a mixed affect. Using a food restriction model of overeating we examined whether bingeing was capable of supporting conditioned taste avoidance (CTA). Adult male Sprague-Dawley rats were maintained on either an ad lib (n = 8) or restricted (50% of regular consumption; n = 24) food access for 20 days. On Days 9, 14, and 19 all rats were given access to a novel saccharin solution in place of water, and two groups of food restricted rats were given access to either 100% of regular food consumption or ad lib food. Ad lib access in the restricted rats induced significant overeating on all three exposures. After all rats were returned to ad lib feeding, a 24 h two-bottle saccharin/water choice test displayed significantly reduced saccharin consumption in the overeating rats, compared to those in the other 3 groups. To determine whether this avoidance was due to a learned association, a second experiment used a latent inhibition paradigm, familiarizing half the rats with the saccharin for 8 days prior to pairing it with overeating. Using the design of Experiment 1, with only the continuously ad lib and the restricted to ad lib feeding groups, it was found that the overeating-induced saccharin avoidance was attenuated by the pre-exposure. These results suggest that self-induced overeating is capable of supporting a learned avoidance of a novel solution suggestive of a conditioned satiety or taste avoidance.     

Chronic food restriction and reduced dietary fat: risk factors for bouts of overeating

The purpose of this study was to determine the effect of chronic food restriction and reduced dietary fat on feeding behavior and body weight. Young female rats were fed ad lib or food restricted on a low-fat (LF) or a fat-free (FF) diet for 4 weeks. Rats then received 24-h free access to 2 diets, the maintenance diet (LF or FF) plus a novel high-fat (HF) diet (24-h intake test). After the test, all the rats were allowed chronic free access to the HF diet until body weight was stable. During the 24-h test, the restricted groups ate significantly more calories than the ad lib groups, and the FF-restricted rats ate significantly more total food, carbohydrate and protein than the LF-restricted rats; there were no differences between the two ad lib groups. During chronic free access to the HF diet, the formerly restricted rats achieved and defended lower body weights than the formerly non-restricted rats. Throughout the experiment, the ad lib groups had more body fat than the restricted groups independent of the dietary subgroup. Hence, a history of chronic food restriction predisposes to consuming more food in acute feeding situations, particularly when dietary fat is reduced, and lowers the level of body weight maintained and defended. Chronic food restriction accompanied by reduced dietary fat may increase risk for bouts of overeating.     

One day of food restriction does not result in an increase in subsequent daily food intake in humans

The purpose of this study was to examine the effect of one day of food restriction on subsequent spontaneous daily food intake and the recovery of body weight in humans. Twenty-two, non-restrained females were fed from Monday to Friday for four weeks using food prepared and measured in the Cornell Metabolic Laboratory. For the first week, all participants ate ad libitum. For each subsequent Monday, participants were divided into three groups in which either they (a) ate ad libitum, (b) were restricted to eating 1200 kcal (5040 kj), or (c) were fasted. From Tuesday until Friday participants ate ad libitum. During each session, all food consumed as well as body weight were measured.Body weight did not change following the day of ad libitum eating, but decreased significantly after the day of food restriction decreasing still further after fasting, indicating high compliance with study protocol. Although the loss in body weight was regained within four days, the recovery was accomplished without any increase in spontaneous food intake. Although no direct measurement of energy expenditure was made in this study, the results strongly suggest that decreases in metabolic rate play a more dominant role in the recovery of body weight following food restriction than the control of food intake.     

Reproductive consequences of food restricition at low temperature in lines of mice divergently selected for thermoregulatory nesting

Female mice of lines divergently selected for thermoregulatory nesting were mated at 5°C and were fed eitherad libitum or restricted diets. Gestation period and litter size at birth were not affected by food restriction, but both fertility and litter size at weaning were significantly reduced by restriction. The reduction in litter size by restricted females was positively associated with the weight of both females and pups at weaning. The pattern of response to food restriction was generally more conservative than that expected on the basis of r-selection predictions. There was also a significant reduction in the proportion of males weaned by restricted females. Differences among the selected lines in both feeding regimes were generally consistent with the hypothesis that thermoregulatory nesting has a positive genetic correlation with Darwinian fitness at low temperatures.     

Synchronization of daily rhythms of locomotor activity and plasma glucose, cortisol and thyroid hormones to feeding in Gilthead seabream (Sparus aurata) under a light-dark cycle

Food availability is far from constant but tends to be cyclic, and fish therefore show a variety of circadian rhythms which can be entrained to feeding time. The aim of this study was to investigate the synchronization to mealtimes of behavioral (locomotor activity), metabolic (glucose) and endocrine (cortisol and thyroid hormones) daily rhythms in gilthead seabream. To this end, fish were reared under a 12:12 LD cycle and fed 1% of their body weight once a day either at mid-light (ML) or at mid-dark (MD) of the LD cycle. Fish synchronized their locomotor activity to the phase in which food was delivered, ML and MD fish displaying 86 ± 3% and 81 ± 1% of their total daily activity during daytime and nighttime, respectively. Daily variations of blood glucose were strongly synchronized to feeding time in both experimental groups, peaking 8 h after the meal. A postprandial cortisol peak was observed in both groups. In fish fed at MD the cortisol values were high during the 8 h following feeding, whereas in fish fed at ML cortisol levels returned to basal values within 4 h. In addition, MD fish showed a higher average daily cortisol value (24.75 ± 2.65 ng/ml) than ML fish (10.30 ± 2.18 ng/ml). Feeding time affected the magnitude of daily variations in the thyroid hormones. When the time of feeding was delayed by 12 h, a shift of the same magnitude could be observed in the glucose daily rhythm and a dramatic change in the cortisol levels of the ML-fed group compared with results mentioned above. In summary, gilthead seabream synchronized their locomotor activity to the phase when food was provided and showed different degrees of synchronization of their behavioral, metabolic and endocrine rhythms to feeding time. Since these parameters are used to evaluate stress responses and welfare in seabream, their daily rhythm and synchronization to light and feeding time should be taken into account.     

Effects of Cyclic Starvation-Feeding and of Splenectomy on the Development of Hemosiderosis in Rat Livers

The development of siderosis of liver and spleen was investigated in rats subjected alternately to periods of starvation and periods of feeding of diets rich in iron (0.71% or 1.23% Fe) or of control diets, during periods ranging up to 245 days. With 0.71% iron in the diet, cyclic starvation-feeding markedly enhanced the accumulation of iron in rat livers by comparison to feeding ad libitum even though rats fed ad libitum ingested far greater total amounts of iron than cyclically fed rats. With 1.23% iron in the diet, the concentration of iron in livers reached more or less the same plateau in cyclically starved-fed rats and in rats fed ad libitum (betwen 4 and 5 mg Fe/g wet weight); but the mean rate of accumulation of iron in the livers of cyclically starved and fed rats was more than twice that in rats fed ad libitum, whereas mean ingestion of iron per feeding day was only 16% higher in the former group. Surgical removal of the spleen enhanced the accumulation of iron in the liver in cyclically starved-fed rats and in rats fed ad libitum. Histologically, siderosis of the liver was moderate in rats fed the diet with 0.71% iron but was severe in rats fed the diet with 1.23% iron and most severe in those without spleens. Stainable iron was deposited in hepatocytes and in Kupffer cells. None of the rats developed cirrhosis of the liver. The data suggest that in rats a barrier to the absorption of iron from the gut, or to its later utilization, is surmounted if the concentration of iron in the food exceeds a certain limit value, somewhere between 0.71 and 1.23%. With iron in the food below this value, cyclic starvation-feeding markedly potentiates accumulation of iron in the liver in the course of several months, but siderosis is moderate. With iron in the food above the limit value, cyclic starvation-feeding and feeding ad libitum can equally lead to massive siderosis of the liver.     

Further studies on collateral ligaments of knee and intertarsal joints in domestic fowl

Collateral ligament attachments in distal femora and distal tibiotarsi were examined in broilers on ad libitum and restricted feeding and in laying strain fowls fed ad libitum. Histopathological studies revealed morphological changes in ligaments of ad libitum-fed broilers which were less apparent or absent in other birds examined. One such change was loss of crimp pattern in collagen bundles of ligaments, which suggested that structural derangement had occurred. Chondroid metaplasia and foci of hyaline cartilage were observed in ligaments of ad libitum-fed broilers and may result from tissue ischaemia. Similarities were noted between ligament attachments in broilers and Osgood-Schlatter disease in man; lesions in broilers may well have a similar aetiology. It is concluded that although feed restriction restores some semblance of normality in broiler ligaments, the propensity for abnormality remains and becomes apparent in heavier birds. Such reasoning casts doubt on the wisdom of modern broiler breeding practice where feed restriction can mask genotypic predisposition to clinical disease.     

Resistance training attenuates fat mass regain after weight loss in ovariectomized rats

Objective

The aim of the present study was to investigate the effects of maintaining only one of the two components of a food restriction (FR) + resistance training (RT) regimen on the regain of body weight and fat mass (liver and adipocytes) in ovariectomized (Ovx) rats.

Methods

Five week Ovx rats were submitted to a weight loss program consisting of a 26% FR combined with RT (OvxFR + RT) for 8 weeks. RT consisted of climbing a 1.5 m vertical grid with a load attached to the tail, 20–40 times with progressively increasing loads 4 times/week. Following this weight loss intervention, OvxFR + RT rats were sub-divided into 3 groups for an additional 5 weeks: 2 groups went back to a normal ad libitum feeding with or without RT and the other group kept only FR.

Results

Combined FR + RT program in Ovx rats led to lower body mass gain, liver triacylglycerol (TAG) levels, and fat mass gain compared to sedentary normally fed Ovx rats (P < 0.01). Stopping both FR and RT over a 5 week period resulted in the regain of body weight, intra-abdominal fat pad weight and liver TAG (P < 0.01). When only FR was maintained, the regain of body and fat pad weight as well as liver and plasma TAG concentrations was completely prevented. However, when only RT was maintained, regain in the aforementioned parameters was attenuated but not prevented (P < 0.05).

Conclusion

It is concluded that following a FR + RT weight loss program, continuation of only RT constitutes an asset to attenuate body weight and fat mass regain in Ovx rats; although the impact is less than the maintaining FR alone. These results suggest that, in post-menopausal women, RT is a positive strategy to reduce body weight and fat mass relapse.     

Effect of chronic caloric restriction on physiological variables related to energy metabolism in the male Fischer 344 rat

In the present study, a number of physiological and behavioral measures that are related to metabolism were continuously monitored in 19-month-old male Fischer 344 rats that were fed ad libitum or fed a caloric restricted diet. Caloric restricted rats ate fewer meals but consumed more food during each meal and spent more time eating per meal than did rats fed ad libitum. Therefore, the timing and duration of meals as well as the total number of calories consumed may be associated with life extension. Average body temperature per day was significantly lower in restricted rats but body temperature range per day and motor activity were higher in restricted rats. Dramatic changes in respiratory quotient, indicating rapid changes in metabolic pathway and lower temperature, occurred in caloric restricted rats when carbohydrate reserves were depleted. Lower body temperature and metabolism during this time interval may result in less DNA damage, thereby increasing the survival potential of restricted rats. Nighttime feeding was found to synchronize physiological performance between ad libitum and caloric restricted rats better than daytime feeding, thereby allowing investigators to distinguish the effects of caloric restriction from those related solely to the time-of-day of feeding.     

Effects of aging and every-other-day feeding on the levels of oxygen radicals in rat brain slices

Caloric and food restriction attenuate oxidative stress. The effect of aging and every-other-day (EOD) feeding on oxygen radical-dependent chemiluminescent intensity was examined in ex vivo brain slices from Fischer rats during oxygenation and hypoxia-reoxygenation with lucigenin, a chemilumigenic probe used for detecting superoxide anion radicals. The chemiluminescent intensity increased during reoxygenation after hypoxic treatment, and the chemiluminescence in the brain slices at the baseline and during reoxygenation increased with age. However, no difference was observed in the superoxide-dependent chemiluminescence between brain slices prepared from the aged rats fed EOD and those fed ad libitum. Our results indicated that age-dependent increases in superoxide production might be associated with enhanced oxidative stress in aged Fischer rat brains. However, the present study newly indicated that decreased superoxide production might not be a major causal factor in caloric and food restriction attenuated oxidative stress.     

Absence of post-fast food compensation in the golden hamster (Mesocricetus auratus).

Ad lib food intakes and body weights were measured for hamsters fed one of 4 different diets. Animals were then placed on an intermittent starvation (IS) schedule in which food was available ad lib on alternate days only. Hamsters of both sexes showed little or no post-fast food compensation, i.e., after 24 hr of food deprivation their daily food intake was no greater than their daily intake during baseline testing. These animals lost a large percentage of their initial body weight and many of them died. Other hamsters restricted daily to half-day feeding periods that nearly coincided with the light (L) or dark (D) phases of the illumination cycle also failed to show food compensation; they generally ate no more during D- or L-periods that followed a half day of food deprivation than during D- or L-periods that succeeded a half day of ad lib feeding. These animals lost substantial portions of their initial body weight and many died. Hamsters refed after a 96-hr fast and an 18% loss in body weight also did not increase their food intake substantially above baseline values. In each of these experiments substantial portions of the body weight lost during starvation were not regained during extended ad lib refeeding regimens. These findings contrast strikingly with the behavior of rats tested concurrently; rats showed a dramatic post-fast hyperphagia, rapid recovery of body weight lost during starvation, and a reversal of the normal nocturnal feeding pattern when refeeding began during L-periods. Hamsters' nocturnal rhythms of eating and drinking were remarkably stable in the face of all the experimental manipulations. However, hamsters, as well as rats, were quite effective in compensating for changes in diet density; a 1:1 dilution of a liquid diet produced a prompt doubling in the volume of diet ingested. Impressive but less complete compensation was recorded when solid diets were diluted with inert substances (kaolin, cellulose). Hoarding and perhaps hibernation rather than compensation may have evolved as adaptations to periods of food scarcity. Noncompensation may be related to hamsters' nonresponsiveness to some signal of energy depletion. The possibility of lipogenesis being a rate-limiting step is considered. The desirability of adequate field data as a prerequisite to laboratory analysis of feeding behavior is emphasized.     

Adaptation to water restriction through dietary selection in weanling rats

For each of five pair of diets, 20 weanling rats were equally divided into ad lib and restricted water groups. Caloric density, palatability, as well as nutrient composition of the diet pairs were manipulated. Though lower in absolute food intake than controls, water-restricted rats took a larger proportion of their food from diets lower in protein content and higher in fat content, regardless of caloric content or palatability. The results demonstrate both a quantitative and qualitative dietary adaptation to water restriction.     

Maternal malnutrition in the rat: Effects on food intake and body weight

The effects of dietary protein level on food intake and body weight were examined in adult female rats during a 35-day pre-mating period and during gestation and lactation. During the pre-mating period, no differences in daily food intake were observed among rats fed a 6% casein, 8% casein or 25% casein diet. However, during this period, rats fed the 6% casein diet gained significantly less weight than those with ad lib access to the 8% or 25% casein diets or than rats pair-fed the 25% casein diet in amounts equivalent to that consumed by rats in the 6% or 8% casein groups. Additionally, rats fed the 6% casein diet displayed decreased efficiency of energy utilization, calculated as weight gain per 100 kilocalories consumed, relative to rats fed the 8% or 25% casein diets. No differences in food intake were observed among the groups during gestation. However, rats fed the 6% casein diet gained less weight than rats fed the 8% or 25% casein diets. During lactation rats fed either the 6% or 8% casein diet consumed significantly less food than animals given the 25% casein diet ad lib. During the second week of lactation, rats receiving ad lib access to the 25% casein diet gained weight while those receiving the 6% or 8% casein diets continued to lose weight. At parturition, body weights of pups did not differ as a function of dietary condition. However, by day 12 of life, pups whose dams had ad lib access to the 25% casein diet weighed significantly more than pups whose dams consumed the 6% or 8% casein diet or whose dams were pair-fed the 25% casein diet in amounts equivalent to those consumed by rats fed the 6% or 8% casein diet.     

Nutritional considerations in the production of rodents for aging studies

Dietary restriction in the maintenance of animals for aging research has been the subject of intense recent interest. This interest may be justified. Current formulas for laboratory animal diets were a natural progression from those for farm animals, but the objectives and conditions for maintaining laboratory and farm animals are often quite different. Indeed, the practice of ad lib feeding current laboratory animal formulations may actually have deleterious effects that can be reduced or eliminated by restricting food intake. This paper reviews many of the major considerations in the development and application of dietary restriction protocols, including formulation, nutritional management during long-term studies, and practical considerations.     

Reproduction and organ weight responses in female rats fed a restricted balanced diet or a restricted nonprotein calorie diet with or without supplemental glutamine or cysteine

Primiparous Sprague-Dawley rats were used in two experiments to test the hypothesis that restriction of carbohydrate and fat calories alone versus comparable restriction of a balanced diet through gestation produces differential effects on gastrointestinal tract, reproductive tract and conceptus development. Rats were assigned on d 1 of pregnancy (13 rats/diet) to the following diets in Expt. 1: (1) balanced control diet fed ad libitum, C; (2) control diet fed at 50% of ad libitum intake, R; (3) restricted nonprotein energy diet containing twice the concentrations of protein, vitamins and mineral elements as the balanced control diet but fed at 50% of ad libitum intake of control diet, RCal; (4) R diet modified plus 0.21% L-cysteine, R + Cys; (5) R diet modified plus 1.54% L-glutamine, R + Glu. In Expt. 2, the treatment groups were: (1) Control diet, C; (2) C diet fed at 50% of ad libitum, R; (3) RCal diet fed at 50% of ad libitum intake of C; (4) RCal diet plus 2% L-glutamine fed at 50% of ad libitum intake of C. All pregnant rats were euthanized on d 20 postcoitum. Body weight of control dams was greater (P less than .01) than that of other dams in both experiments. Uterus weight and litter weight were less in RCal than in other dams in both experiments.(ABSTRACT TRUNCATED AT 250 WORDS)