The role of olfaction in canine food preferences

A bland diet with the odor of meat or air blown through it waspresented to Beagle dogs in daily two choice preference tests.At first, there was a 70% preference for the food that smelledlike meat but, by the third week, the preference had fallento 52%. These results indicated that, although dogs initiallyprefer food that smells like meat, odor must be paired withsome other property of meat, probably taste, for the preferencesto be sustained. Intact dogs significantly preferred lamb overhorsemeat 67±4%, pork over lamb 89±3%, pork overhorsemeat 89±3%, beef over lamb 84±2%, and beefover horsemeat 89±2% in two choice preference tests.Dogs made anosmic by intranasal infusion of zinc sulfate hadpreferences significantly less than those of intact dogs anddid not show a significant preference for one meat over anotherwith the exception of pork, which was preferred to lamb (61±4%).Anosmic dogs showed preferences similar to those of intact dogsfor a sucrose containing over a nonsucrose diet and for a horsemeatcontaining diet over a non-meat diet. These results indicatethat olfaction is important in canine food preferences whichinvolve discrimination between meats, but not for sweet versusnon-sweet and meat versus non-meat preferences.     

Early weaning programs rats to have a dietary preference for fat and palatable foods in adulthood

The objective of this work was to study the effect of early weaning on alimentary preference for the macronutrients protein, carbohydrate and fat in adult rats. Male Wistar rat pups were weaned by separation from the mother at 15 (D15) or 30 (D30) days old. Body weight and food intake were measured every 30 days until pups were 150 days old. At 110 days of age, the alimentary preference was evaluated for 1 h on 3 consecutive days. At 120 days of age, the palatable diet test was conducted during 3 consecutive 24-h periods. Body weight and food intake were not altered, but early weaning in rats induced an alimentary preference to fat and hyperphagia of a palatable diet. In conclusion, early weaning, although did not modify body weight or basal food intake, promoted an increased preference for palatable and fatty foods. This demonstrates that early weaning is not capable of promoting perceptible alterations of alimentary behavior under normal laboratory conditions. However, in the presence of a stimulating factor such as a choice of nutrients or a palatable diet, a possible latent effect on dietary preferences may become apparent. Over the long term, this preference for foods with high caloric density can lead to obesity and metabolic perturbations.     

On food preference in the Red fox

• 1 Foxes treat different prey species in a variety of ways, eating, burying, or discarding them on the basis of preference.
• 2 Because foxes often utilize cached food and because they can remember which prey species is in a given cache the preference effect can be longstanding.
• 3 Evidence from the literature suggests that comparable effects of preference for different species of small mammals affects the diet of wild foxes and their behaviour in the same way as demonstrated in these experiments.
• 4 Certain distastes appear common to all foxes and most carnivores, for instance, insectivore and carnivore meat, in particular that of their own species.
• 5 An incidence of active cannibalism by a fox is reported.
• 6 The effect of food preference is shown to change during the course of one individual's life perhaps as a consequence of such factors as rearing cubs and competition for food.
• 7 One effect of the behavioural consequences of food preference is to defer the decision of what to eat.
• 8 That the fox will kill animals that it does not eat means that populations of animals that are not strictly fox prey are still at risk from fox predatory activity.

     

Food consumption and related water resources in Nordic cities

Many modern cities have strongly invested in the sustainability of their urban water management system. Nordic cities like Stockholm or Copenhagen are amongst pioneers in investments towards integrated urban water management. However, cities can never be fully self-sufficient due to their dependency on external (water) resources. In this paper, we quantify this water dependency with respect to food consumption in nine cities located in the five Nordic countries (Sweden, Denmark, Finland, Norway and Iceland), by means of the water footprint concept. Detailed urban water footprint assessments are scarce in the literature. By analysing national nutrition surveys, we find that urban food intake behaviour differs from national food intake behaviour. In large Nordic cities people eat generally less potatoes, milk products (without cheese), meat and animal fats and they drink less coffee than outside city borders. On the other hand, they generally eat more vegetables and vegetable oils and they drink more tea and alcoholic beverages. This leads consistently – for the six large Nordic cities Stockholm, Malmö, Copenhagen, Helsinki, Oslo and Reykjavik – to slightly smaller food related urban water footprints (−2 to −6%) than national average values. We also analyse the water footprint for different diets based upon Nordic Nutrition Recommendations (NNR) for these cities. We assessed three healthy diet scenarios: 1) including meat (HEALTHY-MEAT), 2) pesco-vegetarian (HEALTHY-PESCO-VEG) and 3) vegetarian (HEALTHY-VEG). This shows that Nordic urban dwellers 1) eat too many animal products (red meat, milk and milk products) and sugar and drink too much alcohol and 2) they eat not enough vegetables, fruit and products from the group pulses, nuts and oilcrops. Their overall energy and protein intake is too high. A shift to a healthy diet with recommended energy and protein intake reduces the urban WF related to food consumption substantially. A shift to HEALTHY-MEAT results in a reduction of −9 to −24%, for HEALTHY-PESCO-VEG the reduction is −29 to −37%, for HEALTHY-VEG the reduction is −36 to −44%. In other words, Nordic urban dwellers can save a lot of water by shifting to a healthy diet.     

Oxytocin mediates the acquisition of filial,odor-guided huddling for maternally-associated odor in preweanling rats

The present study was designed to examine possible roles of oxytocin (OT) in the acquisition of a filial huddling preference in preweanling rats. We used a procedure in which a scented, foster mother can induce an odor-guided huddling preference in preweanling pups, following a single, 2-h-long co-habitation (Kojima and Alberts, 2009, Kojima and Alberts, 2011). This single, discrete period for preference learning enables us to observe the mother–pup interactions that establish the pups' preferences and to intervene with experimental manipulations. Four, 14-day-old littermates interacted with a scented foster mother that provided maternal care during a 2-h session. Two of the pups were pretreated with an intracerebroventricular injection of OT or an oxytocin antagonist (OTA), and the others received a vehicle injection. Filial preference for a maternally-paired odor was measured in a huddling test the next day. OT is necessary for acquisition of the filial preference: The preference learning was blocked in the pups treated with OTA, but not in their vehicle-treated littermates who experienced the same mother at the same time. Injection with exogenous OT did not augment the pups' preference. Manipulating pups' central OT also altered the contact interactions of the mother and pups. When some pups received OT, mother–litter aggregations formed as frequently and with similar combinations of bodies, but contact aggregations were significantly more cohesive than when some pups in the litter received OTA. We discuss dual, behavioral and neuroendocrine roles of OT in social learning by preweanling rats.     

Domestic Dogs in Rural Communities around Protected Areas: Conservation Problem or Conflict Solution?

Although domestic dogs play many important roles in rural households, they can also be an important threat to the conservation of wild vertebrates due to predation, competition and transmission of infectious diseases. An increasing number of studies have addressed the impact of dogs on wildlife but have tended to ignore the motivations and attitudes of the humans who keep these dogs and how the function of dogs might influence dog-wildlife interactions. To determine whether the function of domestic dogs in rural communities influences their interactions with wildlife, we conducted surveys in rural areas surrounding protected lands in the Valdivian Temperate Forests of Chile. Sixty percent of farm animal owners reported the use of dogs as one of the primary means of protecting livestock from predators. The probability of dog–wild carnivore interactions was significantly associated with the raising of poultry. In contrast, dog–wild prey interactions were not associated with livestock presence but had a significant association with poor quality diet as observed in previous studies. Dog owners reported that they actively encouraged the dogs to chase off predators, accounting for 25–75% of the dog–wild carnivore interactions observed, depending on the predator species. Humans controlled the dog population by killing pups and unwanted individuals resulting in few additions to the dog population through breeding; the importation of predominantly male dogs from urban areas resulted in a sex ratios highly dominated by males. These results indicate that dog interactions with wildlife are related to the role of the dog in the household and are directly influenced by their owners. To avoid conflict with local communities in conservation areas, it is important to develop strategies for managing dogs that balance conservation needs with the roles that dogs play in these rural households.     

The milk ejection of the rat,as a stimulus and a response to the litter

A finding that the milk ejection of the rat is stimulated effectively only if at least half the pups are suckled is confirmed. This relationship, however, is found if the mother is anaesthetized but not if the mother is conscious. If the mother is conscious, the milk obtained by individual hungry pups is unaffected by the number of other hungry pups suckled. This is true whether the other pups of the litter are removed, or whether they are present but satiated. After the milk ejection, pups tend to leave the mother's nipple. Milk yield decreases with each milk ejection of a series, but getting less milk does not make the pups more likely to leave the nipple in search of another.     

Neuroethology of olfactory preference development

Young mammals come to approach the odor of their mother, a response that facilitates their survival during early life. Young rats induce a cascade of events in their mother to induce the emission of her odor. The pups increase circulating prolactin levels, which increases food intake and the emission of large quantities of cecotrophe containing the maternal odor. This odor is synthesized by the action of cecal microorganisms and changes with maternal diet. The diet-dependence of the odor requires the pups to acquire their attraction to the odor postnatally. The acquisition of this preference occurs when an odor is paired with the tactile stimulation that pups receive during maternal care. The action of the tactile stimulation appears to be mediated by noradrenaline. The development of this type of olfactory attraction is accompanied by changes in the regions of the olfactory bulb that are responsive to the attractive odor. Metabolic, anatomical, and neurophysiological changes in response to the attractive odor emerge in such regions of the bulb after early olfactory preference training. © 1992 John Wiley & Sons, Inc.     

Neuroethology of olfactory preference development.

Young mammals come to approach the odor of their mother, a response that facilitates their survival during early life. Young rats induce a cascade of events in their mother to induce the emission of her odor. The pups increase circulating prolactin levels, which increases food intake and the emission of large quantities of cecotrophe containing the maternal odor. This odor is synthesized by the action of cecal microorganisms and changes with maternal diet. The diet-dependence of the odor requires the pups to acquire their attraction to the odor postnatally. The acquisition of this preference occurs when an odor is paired with the tactile stimulation that pups receive during maternal care. The action of the tactile stimulation appears to be mediated by noradrenaline. The development of this type of olfactory attraction is accompanied by changes in the regions of the olfactory bulb that are responsive to the attractive odor. Metabolic, anatomical, and neurophysiological changes in response to the attractive odor emerge in such regions of the bulb after early olfactory preference training.     

Oxytocin mediates the acquisition of filial, odor-guided huddling for maternally-associated odor in preweanling rats

The present study was designed to examine possible roles of oxytocin (OT) in the acquisition of a filial huddling preference in preweanling rats. We used a procedure in which a scented, foster mother can induce an odor-guided huddling preference in preweanling pups, following a single, 2-h-long co-habitation ( [Kojima and Alberts, 2009] and Kojima and Alberts, 2011). This single, discrete period for preference learning enables us to observe the mother–pup interactions that establish the pups' preferences and to intervene with experimental manipulations. Four, 14-day-old littermates interacted with a scented foster mother that provided maternal care during a 2-h session. Two of the pups were pretreated with an intracerebroventricular injection of OT or an oxytocin antagonist (OTA), and the others received a vehicle injection. Filial preference for a maternally-paired odor was measured in a huddling test the next day. OT is necessary for acquisition of the filial preference: The preference learning was blocked in the pups treated with OTA, but not in their vehicle-treated littermates who experienced the same mother at the same time. Injection with exogenous OT did not augment the pups' preference. Manipulating pups' central OT also altered the contact interactions of the mother and pups. When some pups received OT, mother–litter aggregations formed as frequently and with similar combinations of bodies, but contact aggregations were significantly more cohesive than when some pups in the litter received OTA. We discuss dual, behavioral and neuroendocrine roles of OT in social learning by preweanling rats.     

Diet selection by adult female Parcoblatta fulvescens cockroaches during the oothecal cycle

1. Female Parcoblatta fulvescens feed selectively on diets differing in nutrient content when given a choice during the reproductive cycle. 2. Diets high in carbohydrate and protein content are preferred early in the cycle, while a cellulose-containing diet is readily consumed toward the end of the cycle. 3. The total diet consumed by females given a choice contained about 16% protein, and they did not excrete uric acid while on this diet. 4. Females on diets high in carbohydrate or cellulose required longer to complete the reproductive cycle than females on high-protein diet or those given a dietary choice. 5. Nitrogen-stressed females will consume urate-containing fecal pellets, but only if they have utilizable carbohydrate in their diet.     

The role of olfactory cues in mother–pup,groupmate, and sex recognition of lesser flat‐headed bats,Tylonycteris pachypus

Tylonycteris pachypus is a gregarious bat species with tens of individuals in a colony. The mechanisms by which mother bats recognize their pups and adult bats recognize each other are not clear. We hypothesized that such recognition is achieved by chemical discrimination and performed experiments to test the hypothesis. Results showed that mother bats were much more attracted to the scent from their own pups. For adult bats, females were attracted to the scent from both male and female groupmates but had a higher preference to the scent from female than from male groupmates. Male bats were much more attracted to the scent from male groupmates while showed no preference to the scent from female groupmates. Within a group, both female and male bats had no difference in preference to the scent from the same or opposite sex. These results suggest that mother–pup and groupmate recognition of T. pachypus can be achieved by olfactory cues.     

The effect of lactating rabbit does on the development of the caecal microbial community in the pups they nurture

AIMS: To study the effect of microbial community of the rabbit does as influenced by dietary factors, on the development of the gut microbiota of their litters. METHODS AND RESULTS: Twenty-four lactating does were given a diet unsupplemented (NAB) or with 100 ppm of bacitracin (BAC) or tiamulin (TIA) to modify their digestive microbiota. Litters were adjusted to six pups. In Trial 1, four does per diet milked their own six pups. In Trial 2, two does per diet nursed three of their pups and three fostered from the doe given the same diet. In Trial 3, two does on each diet nursed three of their pups and three fostered from another doe fed on another diet. Denaturing gradient gel electrophoresis (DGGE) analyses of the litter microbiota showed that the effect of the milking mother was greater than the influence of the biological mother. TIA had a strong effect on the bacterial profile even prevailing over that of the milking mother, in contrast to BAC. CONCLUSIONS: Nursing mother microbiota plays an important role over that of the litter. Caecal colonization that occurs during the lactation process prevailed over that during the partum. SIGNIFICANCE AND IMPACT OF THE STUDY: Manipulation of the mother's microbiota may help for adaptation of the litter microbial community against pathologic digestive processes.     

Basal metabolic rate in carnivores is associated with diet after controlling for phylogeny

Studies of basal metabolic rate (BMR), the minimum metabolic rate of postabsorptive, inactive endotherms while in their rest phase and thermal neutral zone, have contributed significantly to our understanding of animal energetics. Besides body mass, the main determinant of BMR, researchers have invoked diet and phylogenetic history as important factors that influence BMR, although their relative importance has been controversial. For 58 species within the Carnivora, we tested the hypothesis that BMR is correlated with home range size, a proxy for level of activity, and diet, using conventional least squares regression (CLSR) and regression based on phylogenetic independent contrasts (PIC). Results showed that BMR of Carnivora was positively correlated with home range size after controlling for body mass, regardless of the statistical method employed. We also found that diet and mass-adjusted home range size were correlated. When we simultaneously tested the effect of diet and mass-adjusted home range on mass-adjusted BMR, home range size was insignificant because of its colinearity with diet. Then we eliminated home range size from our model, and diet proved to be significant with both CLSR and PIC. We concluded that species that eat meat have larger home ranges and higher BMR than species that eat vegetable matter. To advance our understanding of the potential mechanisms that might explain our results, we propose the "muscle performance hypothesis," which suggests that selection for different muscle fiber types can account for the differences in BMR observed between meat eaters and vegetarian species within the Carnivora.     

Effects of pre- and postnatal protein deprivation and postnatal refeeding on myenteric neurons of the rat large intestine: a quantitative morphological study

We investigated the effect of protein deprivation and refeeding on weight gain, the size of the colon, and the numbers and sizes of enteric neurons. Neurons were located by reduced nicotinamide adenine dinucleotide (NADH) diaphorase staining. Protein deprivation of the mother throughout pregnancy, and the mother and unweaned rat pups in the first 21 postnatal days, reduced the weights of pups to about 50% of control. The size of the colon was also reduced, by about 40%. Despite this, total numbers of neurons in the colon were not reduced. However, there was a small, but significant, 15% reduction in the areas of neuron profiles. After 21 days the remaining pups were removed from the mothers, and either maintained on the control diet, maintained on the protein-deprived diet, or changed from the protein-deprived diet to a normal diet (refed group). These rats were examined after a further 21 days. Refeeding restored body weight to 20% below control, restored colon size, and restored nerve cell size. After a total of 42 days of protein deprivation, nerve cell numbers were not significantly different from control. In undernourished rats at 21 and 42 days, neurons were less well stained than control for NADH diaphorase. Refeeding between 21 and 42 days restored the normal appearance of the neurons. It is concluded that enteric neurons are protected from loss even when there is a substantial reduction in body weight and organ size caused by protein deprivation. The neurons become smaller, but recover size after refeeding.     

Maternal attenuation of hypothalamic paraventricular nucleus norepinephrine switches avoidance learning to preference learning in preweanling rat pups

Infant rats learn to prefer stimuli paired with pain, presumably due to the importance of learning to prefer the caregiver to receive protection and food. With maturity, a more 'adult-like' learning system emerges that includes the amygdala and avoidance/fear learning. The attachment and 'adult-like' systems appear to co-exist in older pups with maternal presence engaging the attachment system by lowering corticosterone (CORT). Specifically, odor-shock conditioning (11 odor-0.5 mA shock trials) in 12-day-old pups results in an odor aversion, although an odor preference is learned if the mother is present during conditioning. Here, we propose a mechanism to explain pups ability to 'switch' between the dual learning systems by exploring the effect of maternal presence on hypothalamic paraventricular nucleus (PVN) neural activity, norepinephrine (NE) levels and learning. Maternal presence attenuates both PVN neural activity and PVN NE levels during odor-shock conditioning. Intra-PVN NE receptor antagonist infusion blocked the odor aversion learning with maternal absence, while intra-PVN NE receptor agonist infusion permitted odor aversion learning with maternal presence. These data suggest maternal control over pup learning acts through attenuation of PVN NE to reduce the CORT required for pup odor aversion learning. Moreover, these data also represent pups' continued maternal dependence for nursing, while enabling aversion learning outside the nest to prepare for pups future independent living.     

Dog Pups’ Attractiveness to Humans Peaks at Weaning Age

The domestic dog (Canis lupus familiaris) is characterized by greatly reduced parenting investment compared with the wild type wolf (C. l. lupus) from which it is descended. Unlike wolf pups, which are reared by both parents into their second year of life, dog pups are abandoned by their mother at weaning around eight weeks of age. This relatively small parental involvement may contribute to the high pup mortality observed in dogs not living as pets. We hypothesized that people would find dog pups most attractive around weaning age when conspecific parental care is significantly reduced and pup mortality rate is high. Younger and older pups would benefit less from human intervention because in the former case the mother is providing care, and in the latter their survival is already compromised. To test this hypothesis, 51 participants rated the attractiveness of 39 black and white headshot photographs presented on a computer screen of dog pups from three breeds (Jack Russell Terrier, Cane Corso, and White Shepherd), from birth to 7 months old. In line with our hypothesis, attractiveness of Cane Corsos peaked at 6.3 weeks of age; Jack Russell Terriers’ attractiveness peaked at 7.7 weeks; and White Shepherds were most attractive at 8.3 weeks. There were also differences in attractiveness between the breeds, with Cane Corsos rated less attractive than the other two breeds. If this attractiveness motivates humans to care for the dog pups and thereby improves pup survival, this could confer significant advantages to dogs, and may contribute to our understanding of the process of domestication.     

Sheep deficient in vitamin E preferentially select for a feed with a higher concentration of vitamin E

Given the capacity of ruminants to modify diet selection based on metabolic needs, we hypothesised that, when given a choice, lambs experiencing a vitamin E deficiency would consume more of a vitamin E-enriched feed than lambs not deficient in vitamin E. Fifty-six Dohne Merino lambs were divided into two groups and fed either a vitamin E-deficient diet over 40 days to induce low plasma vitamin E or a vitamin E-enriched diet to induce high plasma vitamin E. The lambs were then offered a choice of vitamin E-enriched and vitamin E-deficient pellets. For half of the animals, the enriched diet was paired with strawberry flavour and the deficient diet was paired with orange flavour, while the reverse pairings were offered to the others. Lamb preference for the diets was measured daily for the following 15 days. There was a three-way interaction between the high and low vitamin E treatment groups×vitamin E content and type of flavour in the feed×time (days). The lambs preferred pellets flavoured with strawberry but this preference changed to orange flavour in vitamin E-deficient lambs if the orange flavour was paired with high vitamin E. Lambs without a deficiency continued to prefer strawberry-flavoured pellets, regardless of the vitamin E concentrations in the pellets. It is possible that self-learning contributed to the low vitamin E group of lambs changing preference to orange flavour in order to consume more vitamin E, presumably to remediate the deficiency.     

Maternal high-fat diet induces sex-specific endocannabinoid system changes in newborn rats and programs adiposity,energy expenditure and food preference in adulthood

Early life inadequate nutrition triggers developmental adaptations and adult chronic disease. Maternal high-fat (HF) diet promotes visceral obesity and hypothalamic leptin resistance in male rat offspring at weaning and adulthood. Obesity is related to over active endocannabinoid system (ECS). The ECS consists mainly of endogenous ligands, cannabinoid receptors (CB1 and CB2), and the enzymes fatty acid anandamide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). We hypothesized that perinatal maternal HF diet would regulate offspring ECS in hypothalamus and brown adipose tissue (BAT) at birth, prior to visceral obesity development, and program food preference and energy expenditure of adult offspring. Female rats received control diet (C, 9% fat) or isocaloric high-fat diet (HF, 28% fat) for 8 weeks before mating, and throughout gestation and lactation. We evaluated C and HF offspring at birth and adulthood. At birth, maternal HF diet decreased leptinemia and increased hypothalamic CB1, orexin-A, and proopiomelanocortin while it decreased thyrotropin-releasing hormone (Trh) in male pups. Differentially, maternal HF diet increased hypothalamic CB2 in female pups. In BAT, maternal HF diet decreased CB1 and increased CB2 in male and female pups, respectively. Besides presenting different molecular ECS profile at birth, HF adult offspring developed overweight, higher adiposity and high-fat diet preference, independently of the sex, but only males presented hyperleptinemia and higher energy expenditure. In conclusion, maternal HF diet alters ECS components and energy metabolism targets in hypothalamus and BAT of offspring at birth, in a sex-specific manner, which may contribute for hyperphagia, food preference and higher adiposity later in life.     

High fat feeding of lactating mice causing a drastic reduction in fat and energy content in milk without affecting the apparent growth of their pups and the production of major milk fat globule membrane components MFG-E8 and butyrophilin

Lactating mice were fed either a low fat or a high fat diet. Milk samples were collected and the composition was examined. Triglyceride and free fatty acid contents were greatly reduced in the milks of high fat diet group, while protein and lactose contents were almost the same between both diet groups. Although the energy content of each component was also lower in milk of high fat diet group, there was apparently no significant difference in the growth of the pups raised by either diet group. This discrepancy might be in part explained by a hypothesis that the pups might monitor calorie content in milk and keep suckling until the energy intake reaches their satisfaction. Moreover, nearly the same amounts of major milk fat globule membrane proteins MFG-E8 and butyrophilin were shown to be present in the milks from both diet groups and gene expression of both proteins in the mammary glands were also indistinguishable, suggesting that production of major MFGM components is not simply related to fat production and secretion.