Free Feeding Research Articles

Combination of meal and exercise timing with a high-fat diet influences energy expenditure and obesity in mice

In mice, obesity has been observed not only in those freely fed a high-fat diet (HFD) but also in those fed while physically inactive. In contrast, a HFD during physically active periods protects against obesity and the impairments in the circadian rhythm induced by free feeding of a HFD. Although exercise is known to be effective for obesity prevention and management, the optimal timing of exercise has not yet been determined. In the present experiments, we aimed to determine the best combination of daily timing of HFD consumption and exercise for the prevention of HFD-induced weight gain in mice. In this experiment, “morning” refers to the beginning of the active phase (the “morning” for nocturnal animals). Increases in body weight related to free feeding of a HFD was significantly reduced with 4 h of exercise during the late (evening) or middle (noon) active period compared to 4 h of exercise during the early (morning) active period or free access to exercise, which resulted in hours of exercise similar to that of morning exercise. These results suggested that eating in the morning or at noon followed by exercise in the evening could prevent weight gain more effectively than exercise in the morning followed by eating at noon or in the evening. The group fed a HFD for 4 h in the morning had lower body weight than the group fed a HFD for 4 h in the evening without exercise. The last group of experiments tested the hypothesis that there would be an interaction between mealtime and exercise time (i.e. time of day) versus order (i.e. which comes first) effects. We compared groups that exercised for 4 h at noon and were fed either in the morning or evening and groups that were fed for 4 h at noon and either exercised in the morning or evening. We found that the groups that were fed before exercise gained less body and fat weight and more skeletal muscle weight compared to the groups that exercised before eating. Corresponding to the body and fat weight changes, the respiratory exchange ratio (RER) was lower and energy expenditure was higher in the groups fed before exercise than in the groups fed after exercise, and these effects on energy metabolism were also observed in the early stage of HFD feeding before obesity. When obese mice fed a HFD for 12 weeks were exposed to a combination of feeding and exercise timing in an effort to reduce body weight, eating followed by exercise resulted in greater weight loss, similar to the experiments conducted to prevent weight gain. These results demonstrate that a combination of daily timing of eating and exercise may influence weight gain and that eating followed by exercise may be effective for minimizing increases in body and fat weight as well as maximizing increases in skeletal muscle weight.

Identification, optimization, and pharmacology of acylurea GHS-R1a inverse agonists.

Ghrelin plays a major physiological role in the control of food intake, and inverse agonists of the ghrelin receptor (GHS-R1a) are widely considered to offer utility as antiobesity agents by lowering the set-point for hunger between meals. We identified an acylurea series of ghrelin modulators from high throughput screening and optimized binding affinity through structure-activity relationship studies. Furthermore, we identified specific substructural changes, which switched partial agonist activity to inverse agonist activity, and optimized physicochemical and DMPK properties to afford the non-CNS penetrant inverse agonist 22 (AZ-GHS-22) and the CNS penetrant inverse agonist 38 (AZ-GHS-38). Free feeding efficacy experiments showed that CNS exposure was necessary to obtain reduced food intake in mice, and it was demonstrated using GHS-R1a null and wild-type mice that this effect operates through a mechanism involving GHS-R1a.

Effect of feeding behavior on circadian regulation of endothelin expression in mouse colon

AimsThe function, regulation and gene expression of the endothelin (ET) system in the intestine is not well understood. We investigated the dependence on feeding schedule and biological clock of the regulation of ET-1 gene expression in mouse colon. Main methodsMice were fed freely, fasted for 48h and re-fed after fasting. Key findingsWhere indicated ET-1 gene expression was highest in the colon compared with other tissues examined in fasted mice. Fasting increased the level, while maintaining the rhythmicity, of ET-1 gene expression in epithelial colonic tissue. Re-feeding, however, decreased ET-1 gene expression and suppressed rhythmic oscillation, and the rhythmicity also changed for gene expression for circadian clocks, period-1 and period-2 (Per1 and Per2). Furthermore, the decrease in ET-1 gene expression induced by re-feeding was blocked by pre-treatment with hexamethonium and atropine. The daily change in ET-1 gene expression in colon, which depends on feeding schedule via the autonomic nervous system, is synchronized with peripheral circadian oscillators under conditions of free feeding and fasting but not re-feeding. The decrease in ET-1 gene expression in the proximal colon induced by re-feeding occurs via the nervous system. SignificanceET-1 plays an important physiological role, which is dependent on feeding behavior.

Controlling access time to a high-fat diet during the inactive period protects against obesity in mice

Free feeding (FF) with a high fat diet (HFD) causes excessive body weight gain, whereas restricted feeding (RF) with a HFD attenuates body weight gain. The effects of timing of feeding with a HFD (day vs. night) and feeding duration on energy homeostasis have not yet been investigated. In this study, we fed mice a HFD or a normal diet (ND) twice a day, during their active and inactive periods, on a schedule. The amount of food was regulated by feeding duration (2, 4 or 8 h). First, we investigated the effects of 4-h RF during active–inactive periods (ND–ND, HFD–HFD, ND–HFD or HFD–ND). Among all the 4-h RF groups, mice consumed almost the same amount of calories as those in the FF[ND] group, even those fed a HFD. Body weight and visceral fat in these three groups were lower than that in the FF[HFD] group. Second, we investigated the effects of RF duration. Body weight and visceral fat were higher in the 8-h groups than in the 4-h groups. Body weight and visceral fat were higher in the 2-h groups than in the 4-h groups even though the 2-h groups had less food. Third, we investigated the effects of eating a HFD during the inactive period, when RF duration was extended (2, 6 or 12 h). Mice were fed with a HFD during the inactive period for 2 h and fed with a ND during the active period for 2, 6 or 12 h. Body weight and visceral fat in these mice were comparable to those in the FF[ND] mice. The results of our first set of experiments suggest that 4-h RF was an adequate feeding duration to control the effect of a HFD on obesity. The results of our second set of experiments suggest 2-h RF (such as speed-eating) and 8-h RF, representative of eating disorders, are unhealthy feeding patterns related to obesity. The results of our third set of experiments suggest that eating a HFD for a short period during the night does not affect body weight and visceral fat. Taken together, these results indicate that consideration to feeding with a HFD during the inactive period and restricting eating habits relieve the risks of body weight gain and visceral fat accumulation.

Assessing stability of body weight in the brushtail possum (Trichosurus vulpecula).

When conducting controlled laboratory studies with non-traditional laboratory animals it is important that methods for determining body weight stability are reliable. This helps ensure the health and welfare of animals when they are maintained during periods of free feeding or food restriction. This study compared different methods for determining body weight stability in six common brushtail possums (Trichosurus vulpecula) maintained on a free-feeding diet under laboratory conditions. A criterion of five consecutive weighings with less than ±2.5% change across days and no more than two consecutive days of weight loss or weight gain was judged to be the most suitable criteria for determining stability. It is important to study non-traditional animals, especially endangered or pest species, under controlled laboratory conditions and to have robust methods for establishing body weight stability.

A single daily meal at the beginning of the active or inactive period inhibits food deprivation–induced fatty liver in mice

Food deprivation (FD) induces hepatic steatosis in both rodents and humans. Although body composition, age, and sex influence hepatic triglyceride (TG) levels after FD, whether feeding patterns affect FD-induced liver TG increases is unknown. We hypothesized that restricted feeding (RF) of 1 meal per day during the active or inactive period (especially the inactive period) augments FD-induced elevation of liver TGs because RF in the inactive period impairs the circadian rhythm. Triglyceride levels and the expression of genes related to TG metabolism in the liver were examined by a bioassay and real-time reverse transcription–polymerase chain reaction, respectively. In the first experiment, when compared to nonfasted mice, mice that fasted for 24 hours showed a 1.5-fold (FD starting during the inactive period) to 3-fold (FD started during the active period) increase in liver TG levels. This experiment showed that TG levels depend upon the starting time of FD. In the second experiment, mice were given free access to food for 3 hours at the beginning of either the inactive (“supper-only”) or the active (“breakfast-only”) period for 2 weeks. Restricted feeding inhibited the FD-induced increases in liver and serum TG levels, serum free fatty acids, and the expression of genes related to fatty acid uptake in the liver, including fatty acid transport protein 1 (Fatp1) and 4 (Fatp4). Unexpectedly, compared to free feeding, RF during the active or inactive period resulted in resistance to FD-induced fatty liver. This is the first study to demonstrate that feeding patterns affect FD-induced TG accumulation in the mouse liver.

The off feeding intervals effect on some performance traits of broilers

This study was conducted to evaluate the effect of feed restricted (off-feeding intervals) on feed intake, water intake, body weight gain, growth rate, feed conversion ratio, mortality, and dressing percentage of broilers. Two hundred fourty, one day old unsexed, (Ross 308) broiler chicks were randomly distributed into four treatment groups. Each group included three replicates each one had 20 birds. Those assigned as; Control group (T1): birds were fed ad libtium, T2 group feed removed from 8 Am. to 4 Pm., T3 group feed removed from 4 Pm. to 8 Am., T4 group feed removed 8 Am. to 8Am. (skip-a day) all birds were allowed to access feed for above intervals for 8-21 days of age, and re-full fed for the remaining of experiment period 42 days. The results indicated that feed restriction system did significantly (P<0.05) affect live body weight, body weight gain, and feed conversion ratio on starter diet period. Feed restriction significantly P<0.05 reduced feed consumption accompanied with water consumption positively correlated, decreases mortality in restriction period and at marketing, and increase dressing percentage, improved characteristics of carcasses at marketing age, the compensatory growth may be appeared after re-full free feeding for restricted groups to reach a close the market weight as control group., that was indicated by an increase in growth rate post feed restriction period especially at week (6th) as compared with the control group

Amphetamine reward in food restricted mice lacking the melanin-concentrating hormone receptor-1

Chronic food restriction (FR) and maintenance of low body weight have long been known to increase the rewarding and motor-activating effects of addictive drugs. However, the neurobiological mechanisms through which FR potentiates drug reward remain largely unknown. Melanin-concentrating hormone (MCH) signaling could be one of these mechanisms since this peptide is involved in energy homeostasis and modulates mesolimbic dopaminergic transmission. The purpose of the present study was to test this hypothesis by investigating the impact of FR on amphetamine reward in wild-type (WT) and knockout mice lacking the melanin-concentrating hormone receptor-1 (MCHR1-KO). The rewarding effects of amphetamine (0.75–2.25mg/kg, i.p.) were measured with the conditioned place preference (CPP) technique. The food of the mice was restricted to maintain their body weight at 80–85% of their free-feeding (FF) weight throughout the entire CPP experiment. Locomotor activity of the animals was recorded during the conditioning sessions. Our results show that locomotion of all the food-restricted mice treated with saline or amphetamine increased over the sessions whatever the genotype. On the place preference test, the amplitude of CPP induced by 0.75mg/kg amphetamine was higher in food restricted WT mice than in free-fed WT mice and food restricted MCHR1-KO mice. However, FR did not affect amphetamine reward in MCHR1-KO mice. The present results indicate that MCH signaling could be involved in the ability of FR to increase amphetamine-induced CPP.

Exercising for food: bringing the laboratory closer to nature.

Traditionally, exercise physiology experiments have borne little resemblance to how animals express physical activity in the wild. In this experiment, 15 adult male rats were divided into three equal-sized groups: exercise contingent (CON), non-exercise contingent (NON) and sedentary (SED). The CON group was placed in a cage with a running wheel, where the acquisition of food was contingent upon the distance required to run. Every 3 days the distance required to run to maintain food intake at free feeding levels was increased by 90% in comparison to the previous 3 days. The NON group was housed identically to the CON group, but food acquisition was not dependent upon running in the wheel. Finally, the SED group was kept in small cages with no opportunity to perform exercise. A two-way ANOVA with repeated measures was used to determine significant differences in responses between the experimental phases and treatment groups, and ANCOVA was used to analyse growth and tissue mass variables with body length and body mass used separately as covariates. A post hoc Tukey's test was used to indicate significant differences. A Pearson's correlation was used to test the relationship between the distance travelled by the animal and the distance/food ratio. The level of significance was set at P<0.05 for all tests. The CON group showed the hypothesized correlation between distance required to run to obtain food and the mean distance travelled (P<0.001), during 45 days in the contingency phase. This group showed a decrease in body mass, rather than an increase as shown by NON and SED groups. The CON group had a significantly lower body temperature (P<0.05) and adiposity (P<0.05) when compared with the other two groups for the same body size. The present experimental model based on animals choosing the characteristics of their physical exercise to acquire food (i.e. distance travelled, speed and duration) clearly induced physiological effects (body characteristics and internal temperature), which are useful for investigating relevant topics in exercise physiology such as the link between exercise, food and body mass.

The behavioral satiety sequence in pigeons (Columba livia). Description and development of a method for quantitative analysis

The postprandial event known as the specific dynamic action is an evolutionarily conserved physiological set of metabolic responses to feeding. Its behavioral counterpart, a sequence of drinking, maintenance (e.g., grooming) and sleep-like behaviors known as the behavioral satiety sequence (BSS), has been thoroughly described in rodents and has enabled the refined evaluation of potential appetite modifiers. However, the presence and attributes of a BSS have not been systematically studied in non-mammalian species. Here, we describe the BSS induced in pigeons (Columba livia) by 1) the presentation of a palatable seed mixture (SM) food to free-feeding animals (SM+FF condition) and 2) re-feeding after a 24-h fasting period (FD24h+SM), which was examined by continuous behavioral recording for 2h. We then compare these patterns to those observed in free-feeding (FF) animals. A set of graphic representations and indexes, drawn from these behaviors (latency, time-to-peak, inter-peak intervals and the first intersection between feeding curves and those of other BSS-typical behaviors) were used to describe the temporal structure and sequential relationships between the pigeon's BSS components. Cramér–von Mises-based statistical procedures and bootstrapping-based methods to compare pairs of complex behavioral curves were described and used for comparisons among the behavioral profiles during the free-feeding recordings and after fasting- and SM-induced BSS. FD24h+SM- and SM+FF-induced feeding were consistently followed by a similar sequence of increased bouts of drinking, followed by preening and then sleep, which were significantly different from that of FF birds. The sequential and temporal patterns of the pigeon's BSS were not affected by differences in food intake or by dissimilarity in motivational content of feeding stimuli. The present data indicated that a BSS pattern can be reliably evoked in the pigeon, in a chronological succession and sequence that strongly resembled that observed in rodents and primates. This pattern can be quantitatively described and compared using different suitable and coordinated behavioral measures, enabling further studies on the comparative and evolutionary aspects of the mechanisms that shape the post-consummatory behavioral flux in amniotes.

Infant Emotional Withdrawal: A Precursor of Affective and Cognitive Disturbance in Fetal Alcohol Spectrum Disorders

Our aim was to test the hypothesis that emotional withdrawal is an early indicator of affective disorder in infants heavily exposed prenatally to alcohol, which is independent of alcohol-related effects on mother-infant interaction and temperament and discriminated between children later diagnosed with fetal alcohol syndrome (FAS) and partial FAS (PFAS) and predicted cognitive and affective outcomes at 5 and 9years. The sample consisted of Cape Coloured (mixed ancestry) infants, whose mothers were interviewed during pregnancy regarding their alcohol consumption using a timeline follow-back approach. Infant emotional withdrawal (n=85) was assessed on the Alarm Distress Baby Scale at 6.5months. Mother-infant interaction was evaluated from video recordings during free play and infant feeding at 6.5months (n=127). Infant temperament was assessed by maternal report on the EAS Temperament Survey at 13months (n=119). Sociodemographic and psychological correlates of maternal alcohol use and infant iron deficiency were examined as potential confounders. The children were diagnosed for FAS/PFAS by expert dysmorphologists at 5years, cognitive and affective function at 5 and 9years. Prenatal alcohol exposure was associated with increased infant emotional withdrawal and decreased activity, but unrelated to mother-infant interaction or any other temperament measures. Children later diagnosed with FAS and PFAS at 5years exhibited more emotional withdrawal and less responsivity and activity as infants. Infant withdrawal, responsivity, quality of interaction, and maternal sensitivity also predicted poorer IQ and affective response at 5 and 9years. When all 4 infant affective measures were examined simultaneously in a regression analysis, only infant emotional withdrawal persisted as a significant predictor of 9-year IQ. This study is the first to document a direct effect of fetal alcohol exposure on emotional withdrawal in infancy. These data link prenatal alcohol to a specific aspect of infant affective function not attributable to mother-infant interaction, infant temperament, or other socioemotional aspects of the infant's environment and identify infant emotional withdrawal as an early indicator of affective disturbance, particularly in children later diagnosed with FAS and PFAS.

Food Restriction Increases Glutamate Receptor-Mediated Burst Firing of Dopamine Neurons

Restriction of food intake increases the acquisition of drug abuse behavior and enhances the reinforcing efficacy of those drugs. However, the neurophysiological mechanisms responsible for the interactions between feeding state and drug use are largely unknown. Here we show that chronic mild food restriction increases the burst firing of dopamine neurons in the substantia nigra. Dopamine neurons from food-restricted mice exhibited increased burst firing in vivo, an effect that was enhanced by an injection of the psychomotor stimulant cocaine (10 mg/kg, i.p.). Food restriction also enhanced aspartic acid-induced burst firing of dopamine neurons in an ex vivo brain slice preparation, consistent with an adaptation occurring in the somatodendritic compartment and independent of a circuit mechanism. Enhanced burst firing persisted after 10 d of free feeding following chronic food restriction but was not observed following a single overnight fast. Whole-cell patch-clamp recordings indicated that food restriction also increased electrically evoked AMPAR/NMDAR ratios and increased D2 autoreceptor-mediated desensitization in dopamine neurons. These results identify dopamine neurons in the substantia nigra as a convergence point for the interactions between feeding state and drugs of abuse. Furthermore, increased glutamate transmission combined with decreased autoreceptor inhibition could work in concert to enhance drug efficacy in response to food restriction.

Differential effects on natural reward processing in rats after repeated heroin

Heroin users report reward deficits as well as reward enhancements (to drug stimuli). To better understand the causal relation between chronic heroin and alterations in natural reward processing, we used experimental techniques in animal models. Separate groups of rats were trained in several food reward paradigms: conditioned place preference (CPP), food-reinforced lever pressing under a progressive ratio schedule of reinforcement, free feeding, and lever pressing with conditioned reinforcement. After training, the rats were subjected to 10 daily heroin (2mg/kg) or saline vehicle injections and tested at 3, 15, and 30days post-treatment. Repeated heroin treatment abolished the CPP and significantly reduced break points for food reward at 3, 15, and 30days post-treatment. Repeated heroin did not affect free feeding. Finally, repeated heroin significantly enhanced responding for a food-based conditioned reinforcer. Repeated heroin decreases the attractiveness of food-associated cues and reduces motivation to work for natural reward. However, it appears to enhance natural conditioned reward processes that involve the acquisition of novel responding. Thus, repeated heroin appears to produce differential effects on natural reward processing depending on the nature of the reward-directed behavior.

Bear-Baiting May Exacerbate Wolf-Hunting Dog Conflict

BackgroundThe influence of policy on the incidence of human-wildlife conflict can be complex and not entirely anticipated. Policies for managing bear hunter success and depredation on hunting dogs by wolves represent an important case because with increasing wolves, depredations are expected to increase. This case is challenging because compensation for wolf depredation on hunting dogs as compared to livestock is less common and more likely to be opposed. Therefore, actions that minimize the likelihood of such conflicts are a conservation need.Methodology/Principal FindingsWe used data from two US states with similar wolf populations but markedly different wolf/hunting dog depredation patterns to examine the influence of bear hunting regulations, bear hunter to wolf ratios, hunter method, and hunter effort on wolf depredation trends. Results indicated that the ratio of bear hunting permits sold per wolf, and hunter method are important factors affecting wolf depredation trends in the Upper Great Lakes region, but strong differences exist between Michigan and Wisconsin related in part to the timing and duration of bear-baiting (i.e., free feeding). The probability that a wolf depredated a bear-hunting dog increases with the duration of bear-baiting, resulting in a relative risk of depredation 2.12–7.22× greater in Wisconsin than Michigan. The net effect of compensation for hunting dog depredation in Wisconsin may also contribute to the difference between states.Conclusions/SignificanceThese results identified a potential tradeoff between bear hunting success and wolf/bear-hunting dog conflict. These results indicate that management options to minimize conflict exist, such as adjusting baiting regulations. If reducing depredations is an important goal, this analysis indicates that actions aside from (or in addition to) reducing wolf abundance might achieve that goal. This study also stresses the need to better understand the relationship among baiting practices, the effect of compensation on hunter behavior, and depredation occurrence.

Optimisation of Embryonic and Larval ECG Measurement in Zebrafish for Quantifying the Effect of QT Prolonging Drugs

Effective chemical compound toxicity screening is of paramount importance for safe cardiac drug development. Using mammals in preliminary screening for detection of cardiac dysfunction by electrocardiography (ECG) is costly and requires a large number of animals. Alternatively, zebrafish embryos can be used as the ECG waveform is similar to mammals, a minimal amount of chemical is necessary for drug testing, while embryos are abundant, inexpensive and represent replacement in animal research with reduced bioethical concerns. We demonstrate here the utility of pre-feeding stage zebrafish larvae in detection of cardiac dysfunction by electrocardiography. We have optimised an ECG recording system by addressing key parameters such as the form of immobilization, recording temperature, electrode positioning and developmental age. Furthermore, analysis of 3 days post fertilization (dpf) zebrafish embryos treated with known QT prolonging drugs such as terfenadine, verapamil and haloperidol led to reproducible detection of QT prolongation as previously shown for adult zebrafish. In addition, calculation of Z-factor scores revealed that the assay was sensitive and specific enough to detect large drug-induced changes in QTc intervals. Thus, the ECG recording system is a useful drug-screening tool to detect alteration to cardiac cycle components and secondary effects such as heart block and arrhythmias in zebrafish larvae before free feeding stage, and thus provides a suitable replacement for mammalian experimentation.

Ghrelin-Induced Orexigenic Effect in Rats Depends on the Metabolic Status and Is Counteracted by Peripheral CB1 Receptor Antagonism

Ghrelin is an endogenous regulator of energy homeostasis synthesized by the stomach to stimulate appetite and positive energy balance. Similarly, the endocannabinoid system is part of our internal machinery controlling food intake and energy expenditure. Both peripheral and central mechanisms regulate CB1-mediated control of food intake and a functional relationship between hypothalamic ghrelin and cannabinoid CB1 receptor has been proposed. First of all, we investigated brain ghrelin actions on food intake in rats with different metabolic status (negative or equilibrate energy balance). Secondly, we tested a sub-anxiogenic ultra-low dose of the CB1 antagonist SR141716A (Rimonabant) and the peripheral-acting CB1 antagonist LH-21 on ghrelin orexigenic actions. We found that: 1) central administration of ghrelin promotes food intake in free feeding animals but not in 24 h food-deprived or chronically food-restricted animals; 2) an ultra-low dose of SR141716A (a subthreshold dose 75 folds lower than the EC50 for induction of anxiety) completely counteracts the orexigenic actions of central ghrelin in free feeding animals; 3) the peripheral-restricted CB1 antagonist LH-21 blocks ghrelin-induced hyperphagia in free feeding animals. Our study highlights the importance of the animaĺs metabolic status for the effectiveness of ghrelin in promoting feeding, and suggests that the peripheral endocannabinoid system may interact with ghrelińs signal in the control of food intake under equilibrate energy balance conditions.

EFFICIENCY OF LIBRAXR AS AN ANTISTOMACHEC TO OVERCOME BAIT SHYNESS OF ZINC PHOSPHIDE TO BLACK RAT, RATTUS RATTUS

Some laboratory trials were conducted to increase the bait acceptance of zinc phoshide against black rat, Rattus rattus, using LibraxR drug (chlordiazepoxid 5mg + clidinium bromide 2.5mg) as antistomachec. LibraxR 0.001% was tested alone and combined with different concentrations of zinc phosphide bait using non and free choice feeding methods. Results showed that in both methods, LibraxR alone and mixed with zinc phosphid bait significantly increased the average daily consumption and the acceptability of rats. Also it enhanced the percent of mortality comparing with zinc hosphide bait lone.

Effects of Birth Weight and Feeding System on Fattening Performance and Feeding Behaviour of Karayaka Male Lambs

To determine effects of birth weight (BtW) and feeding system on fattening performance and behavioural responses of lambs, after birth 28 Karayaka male lambs were divided into two BtW groups, namely a low BtW (4.1±0.06 kg) and high BtW (5.0±0.09 kg). After weaning (90 days of age), seven lambs in each of these groups were fed individually ad libitum with total mixed ratio (TMR), consisted of 80% of a compound feed and 20% of roughage based on a dry matter basis (140 g crude protein and 2550 kcal ME/kg) and the other seven lambs were fed on the same ingredients as that of TMR but each ingredient was put in separate troughs (free choice feeding, FCF). Therefore the lambs were distributed into four groups according to 2 (low vs high BtW) × 2 (TMR vs FCF) factorial design. Live weight gains and intakes of dry matter, feedstuffs and nutrients of the lambs were affected by the FCF, but not by the BtW and their interaction. The daily weight gain (P<0.01), intakes of soybean meal and corn (P<0.01), dry matter (P<0.05), protein and energy (P<0.01) of FCF-fed lambs were higher than those of TMR-fed lambs. FCF-fed lambs consumed less alfalfa hay, wheat bran and barley than TMR-fed lambs (P<0.01). The FCF increased rumination (P<0.01) and tend to rest more (P<0.05) compared to the TMR. The study suggests that FCF system can assist in enhancing the live weight gain by promoting the protein and energy intakes and by improving the welfare of lambs.

Jejunal morphology and blood metabolites in tail biting, victim and control pigs

Tail biting has several identified feeding-related risk factors. Tail biters are often said to be lighter and thinner than other pigs in the pen, possibly because of nutrition-related problems such as reduced feed intake or inability to use nutrients efficiently. This can lead to an increase in foraging behavior and tail biting. In this study, a total of 55 pigs of different ages were selected according to their tail-biting behavior (bouts/hour) and pen-feeding system to form eight experimental groups: tail-biting pigs (TB), victim pigs (V) and control pigs from a tail-biting pen (Ctb) and control pen (Cno) having either free access to feed with limited feeding space or meal feeding from a long trough. After euthanasia, a segment of jejunal cell wall was cut from 50 cm (S50) and 100 cm (S100) posterior to the bile duct. Villus height, crypt depth and villus : crypt ratio (V : C) were measured morphometrically. Blood serum concentration of minerals and plasma concentration of amino acids (AA) was determined. Villus height was greater in Cno than Ctb pigs in the proximal and mid-jejunum (P < 0.05), indicative of better ability to absorb nutrients, and increased with age in the proximal jejunum (P < 0.001). Serum mineral concentration of inorganic phosphate (Pi) and calcium (Ca) was lower in Ctb compared with Cno pigs, and that of Pi in V compared with all the other pigs. Many non-essential AA were lower in pigs from tail-biting pens, and particularly in victim pigs. Free access feeding with shared feeding space was associated with lower levels of essential AA in blood than meal feeding with simultaneous feeding space. Our data suggest that being a pig in a tail-biting pen is associated with decreased jejunal villus height and blood AA levels, possibly because of depressed absorption capacity, feeding behavior or environmental stress associated with tail biting. Victim pigs had lower concentrations of AA and Pi in plasma, possibly as a consequence of being bitten.

Increased Body Weight of the BAC HD Transgenic Mouse Model of Huntington’s Disease Accounts for Some but Not All of the Observed HD-like Motor Deficits

The genome of the Bacterial Artificial Chromosome (BAC) transgenic mouse model of Huntington’s Disease (BAC HD) contains the 170 kb human HTT locus modified by the addition of exon 1 with 97 mixed CAA-CAG repeats. BAC HD mice present robust behavioral deficits in both the open field and the accelerating rotarod tests, two standard behavioral assays of motor function. BAC HD mice, however, also typically present significantly increased body weights relative to wildtype littermate controls (WT) which potentially confounds the interpretation of any motor deficits associated directly with the effects of mutant huntingtin. In order to evaluate this possible confound of body weight, we directly compared the performance of BAC HD and WT female mice under food restricted versus free feeding conditions in both the open field and rotarod tasks to test the hypothesis that some of the motor deficits observed in this HTT-transgenic mouse line results solely from increased body weight. Our results suggest that the rotarod deficit exhibited by BAC HD mice is modulated by both body weight and non-body weight factors resulting from overexpression of full length mutant Htt. When body weights of WT and BAC HD transgenic mice were normalized using restricted feeding, the deficits exhibited by BAC HD mice on the rotarod task were less marked, but were still significant. Since the rotarod deficit between WT and BAC HD mice is attenuated when body weight is normalized by food restriction, utilization of this task in BAC HD mice during pre-clinical evaluation must be powered accordingly and results carefully considered as therapeutic benefit can result from decreased overall body weight and or motoric improvement that may not be related to body mass. Furthermore, after controlling for body weight differences, the hypoactive phenotype displayed by ad libitum fed BAC HD mice in the open field assay was not observed in the BAC HD mice undergoing food restriction. These findings suggest that assessment of spontaneous locomotor activity, as measured in the open field test, may not be the appropriate behavioral endpoint to evaluate the BAC HD mouse during preclinical evaluation since it appears that the apparent hypoactive phenotype in this model is driven primarily by body weight differences.