The establishment of food preferences and aversions determines the modulation of eating behaviour and the optimization of food intake. These phenomena rely on the learning and memory abilities of the organism and depend on different psychobiological mechanisms such as associative conditionings and sociocultural influences. After summarizing the various behavioural and environmental determinants of the establishment of food preferences and aversions, this paper describes several issues encountered in human nutrition when preferences and aversions become detrimental to health: development of eating disorders and obesity, aversions and anorexia in chemotherapy-treated or elderly patients and poor palatability of medical substances and drugs. Most of the relevant biomedical research has been performed in rodent models, although this approach has severe limitations, especially in the nutritional field. Consequently, the final aim of this paper is to discuss the use of the pig model to investigate the behavioural and neurophysiological mechanisms underlying the establishment of food preferences and aversions by reviewing the literature supporting analogies at multiple levels (general physiology and anatomy, sensory sensitivity, digestive function, cognitive abilities, brain features) between pigs and humans.Keywords: pig, conditioned learning, eating behaviour, animal model, biomedical applications ImplicationsInvestigation of the behavioural and neurophysiological mechanisms of the establishment of food preferences and aversions can lead to important developments in the context of human nutrition and health. Because the rodent models are not always adequate in this field, there is a need to develop alternative experimental models. Pigs have numerous similarities with humans in terms of the physiology, anatomy, sensory sensitivity, cognitive abilities and brain functions. The aim of this paper is to promote the use of pigs for biomedical research in human nutrition. IntroductionFeeding is a complex behaviour, which can be described as 'the research and consumption of food and drink to maintain vital functions ' (Bellisle, 1999) and to 'fulfil the metabolic needs of the organism ' (Ferreira, 2004). Today, it is also well acknowledged that a high proportion of human food consumption in developed countries appears to be driven by pleasure (for a review, see Lowe and Butryn, 2007) and sociocultural influences. Food consumption is also involved in fundamental metabolic homeostasis regulation, as it controls the supply of energy and nutrients in the organism (Bellisle, 1999). According to Ferreira (2004), feeding behaviour implies that animals learn to consume high-energy foods and to avoid toxic foods. Establishment of food selection implies that, during its first experience with food, the organism memorizes the sensorial characteristics of the food (e.g. taste, odour, texture and visual cues) and the postingestive consequences of its ingestion, and associates these food characteristics with these consequences (Garcia et ...

A suboptimal early nutritional environment ( excess of energy, sugar, and fat intake) can increase susceptibility to diseases and neurocognitive disorders. The purpose of this study was to investigate in nonobese Yucatan minipigs () the impact of maternal diet [standard diet (SD) Western diet (WD)] during gestation and 25 d of lactation on milk composition, blood metabolism, and microbiota activity of sows ( 17) and their piglets ( 65), and on spatial cognition ( 51), hippocampal plasticity ( 17), and food preferences/motivation ( 51) in the progeny. Milk dry matter and lipid content, as well as plasma total cholesterol and free fatty acid (FFA) concentrations ( < 0.05) were higher in WD than in SD sows. Microbiota activity decreased in both WD sows and 100-d-old piglets ( < 0.05 or < 0.10, depending on short-chain FAs [SCFAs]). At weaning [postnatal day (PND) 25], WD piglets had increased blood triglyceride and FFA levels ( < 0.01). Both SD and WD piglets consumed more of a known SD than an unknown high-fat and -sucrose (HFS) diet ( < 0.0001), but were quicker to obtain HFS rewards compared with SD rewards ( < 0.01). WD piglets had higher working memory ( = 0.015) and reference memory ( < 0.001) scores, which may reflect better cognitive abilities in the task context and a higher motivation for the food rewards. WD piglets had a smaller hippocampal granular cell layer ( = 0.03) and decreased neurogenesis ( < 0.005), but increased cell proliferation ( < 0.001). A maternal WD during gestation and lactation, even in the absence of obesity, has significant consequences for piglets' blood lipid levels, microbiota activity, gut-brain axis, and neurocognitive abilities after weaning.-Val-Laillet, D., Besson, M., Guérin, S., Coquery, N., Randuineau, G., Kanzari, A., Quesnel, H., Bonhomme, N., Bolhuis, J. E., Kemp, B., Blat, S., Le Huërou-Luron, I., Clouard, C. A maternal Western diet during gestation and lactation modifies offspring's microbiota activity, blood lipid levels, cognitive responses, and hippocampal neurogenesis in Yucatan pigs.

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Maternal DHA beneficially affected offspring social behavior after weaning and mildly attenuated sickness behavior after an inflammatory challenge in pigs. These behavioral changes may be mediated by increased brain DHA proportions.

The importance of optimal early life conditions of broilers to sustain efficient and healthy production of broiler meat is increasingly recognized. Therefore, novel husbandry systems are developed, in which immediate provision of nutrition post hatch is combined with on-farm hatching. In these novel systems, 1-day-old-chick handling and transport are minimized. To study whether early nutrition and reduced transport are beneficial for broiler performance and behavior, the effects of early or delayed nutrition and post-hatch handling and transport were tested from hatch until 35 d of age, in a 2 × 2 factorial arrangement. In total, 960 eggs were hatched in 36 floor pens. After hatch, chicks were given immediate access to water and feed (early nutrition) or after 54 h (delayed nutrition). Eighteen hours after hatch, chicks remained in their pens (non-transported control), or were subjected to short-term handling and transport to simulate conventional procedures. Subsequently, chicks returned to their pens. Compared with delayed-fed chickens, early-fed chickens had greater body weight up to 21 d of age, but not at slaughter (35 d of age). No effects of transport or its interaction with moment of first nutrition were found on performance. At 3 d post hatch, transported, early-fed chicks had a greater latency to stand up in a tonic immobility test than transported, delayed-fed chicks, but only in chicks that were transported. At 30 d post hatch, however, latency was greater in transported, delayed-fed chickens than in transported, early-fed chicks. This may indicate long-term deleterious effects of delayed nutrition on fear response in transported chickens. It is concluded that early nutrition has mainly beneficial effects on performance during the first 2 wk post hatch, but these beneficial effects are less evident in later life. The combination of transport and early nutrition may influence the chicken's strategies to cope with stressful events in early and later life.

This study investigated the behavioural and brain responses towards conditioned flavours with different hedonic values in juvenile pigs. Twelve 30-kg pigs were given four three-day conditioning sessions: they received three different flavoured meals paired with intraduodenal (i.d.) infusions of 15% glucose (FGlu), lithium chloride (FLiCl), or saline (control treatment, FNaCl). One and five weeks later, the animals were subjected to three two-choice feeding tests without reinforcement to check the acquisition of a conditioned flavour preference or aversion. In between, the anaesthetised pigs were subjected to three 18FDG PET brain imaging coupled with an olfactogustatory stimulation with the conditioned flavours. During conditioning, the pigs spent more time lying inactive, and investigated their environment less after the FLiCl than the FNaCl or FGlu meals. During the two-choice tests performed one and five weeks later, the FNaCl and FGlu foods were significantly preferred over the FLICl food even in the absence of i.d. infusions. Surprisingly, the FNaCl food was also preferred over the FGlu food during the first test only, suggesting that, while LiCl i.d. infusions led to a strong flavour aversion, glucose infusions failed to induce flavour preference. As for brain imaging results, exposure to aversive or less preferred flavours triggered global deactivation of the prefrontal cortex, specific activation of the posterior cingulate cortex, as well as asymmetric brain responses in the basal nuclei and the temporal gyrus. In conclusion, postingestive visceral stimuli can modulate the flavour/food hedonism and further feeding choices. Exposure to flavours with different hedonic values induced metabolism differences in neural circuits known to be involved in humans in the characterization of food palatability, feeding motivation, reward expectation, and more generally in the regulation of food intake.

The objective of this study was to evaluate effects of different dosages of dietary nitrate supplementation to sows from d 108 of gestation until d 5 of lactation on reproductive performance of sows and piglet performance from birth until weaning. Dietary nitrate supplementation leads to nitric oxide (NO) formation that can potentially increase blood flow to the fetuses (by the vasodilative effect of NO), leading to a decrease in the loss of potential viable piglets in the form of stillbirth and preweaning mortality. Three hundred and five gilts and sows were allocated to one of six diets from d 108 of gestation until d 5 of lactation, containing 0.00% (Control), 0.03%, 0.06%, 0.09%, 0.12%, or 0.15% of dietary nitrate. The source of nitrate used was calcium nitrate double salt. Calcium levels were kept the same among diets by using limestone. Gilts and sows were weighed and backfat was measured at arrival to the farrowing room (d 108 of gestation) and at weaning (d 27 of age). Data included number of piglets born alive, born dead, and weaned, as well as individual piglet weights at d 0, 72 h of age and weaning. Preweaning mortality was determined throughout lactation. Body weight d 0 (P = 0.04) as well as BW at 72 h of age (P &lt; 0.01) increased linearly with increasing dosages of nitrate in the maternal diet. Litter uniformity (SD) at birth was not affected by maternal nitrate supplementation level (P &gt; 0.10), but tended to be higher at 72 h of age in the control treatment than in all nitrate-supplemented treatments (P = 0.07), and SD decreased linearly (increased uniformity) at weaning with increasing dosages of nitrate (P = 0.05). BW at weaning (P &gt; 0.05) and average daily gain of piglets during lactation (P &gt; 0.05) were not affected by maternal nitrate supplementation. A tendency for a quadratic effect (P = 0.10) of the dosage of maternal dietary nitrate was found on preweaning mortality of piglets with the lowest level of mortality found at 0.09% to 0.12% of maternal nitrate supplementation. We conclude that the use of nitrate in the maternal diet of sows during the perinatal period might stimulate preweaning piglet vitality. Exact mode of action and optimal dose of nitrate still need to be elucidated.

Our study aimed at investigating the effect of feed supplementation, from weaning, with 3 sensory feed additives (FA1, FA2, and FA3) on feed preferences, feed intake, and growth of piglets. The FA1 contained extract of Stevia rebaudiana (10 to 20%), extract of high-saponin plants (5 to 10%), and excipients (70 to 85%), the FA2 was mainly composed of a natural extract of Citrus sinensis (60 to 80%), and the FA3 was made of a blend of extracts of hot-flavored spices (5 to 15%) and excipients (85 to 95%). At weaning (d 1), a total of 32 female piglets housed in individual pens were allocated to 4 treatments (FA1, FA2, FA3, and control [CON]) of equivalent mean weight. The pigs were fed a standard pelleted prestarter diet from weaning (d 1) to d 15 and a starter diet from d 16 to 28. The diets were supplemented with the feed additives (FA) corresponding to their treatment, while the CON treatment was the standard diets with no additive. Feed refusals were weighed daily and piglets were weighed weekly on d 1, 7, 14, 21, and 28. On the day of feed transition (d 16) as well as 7 (d 23) and 10 d (d 26) later, the animals were consecutively subjected to 1- and 22-h double-choice feeding tests to investigate their preferences during a short period and a longer period of time for the CON starter diet and the starter diet added with the FA corresponding to their treatment. No overall effect of the feed additives was observed on ADFI, ADG, G:F, and final BW. No overall preference was highlighted for the FA1 treatment, except for a preference for the FA1 starter diet during the 1-h test on d 23 (78% of total feed intake; P < 0.01). For the FA2 treatment, the pigs consumed the FA2 starter diet more than the CON starter diet during the 22-h tests on d 16 (67% of total feed intake; P < 0.05) and 26 (62% of total feed intake; P < 0.01). For the FA3 treatment, on d 26, the FA3 starter diet was and tended to be consumed more than the CON starter diet during 1- (69% of total intake; P < 0.05) and 22-h (60% of total intake; P < 0.10) tests, respectively. In conclusion, feed supplementation with the FA1, FA2, and FA3 from weaning did not induce beneficial effects on feed intake and growth performance during the early postweaning period. The FA2 increased palatability and acceptance of the unfamiliar starter diet the day of feed transition, while the FA1 and FA3 increased palatability of the starter diet only after a few days of exposure, most likely through long-term familiarization processes.