Associations of body condition score with health conditions related to overweight and obesity in cats.

OBJECTIVES: To explore the associations of cat body condition score with various health conditions, such as diabetes mellitus, dermatological conditions and hypertension, that have been shown to relate to overweight and/or obesity in cats, dogs or humans. MATERIALS AND METHODS: Electronic patient records between January 3, 2005 and June 21, 2015 were obtained from a cat-focused primary accession clinic in metropolitan Sydney where the body condition score of cats was routinely evaluated. Binomial logistic regression modelling was conducted to investigate the associations, after adjusting for age, sex and breed, between 21 health conditions and body condition score recorded on a 9-point scale. RESULTS: Fourteen of the 21 health conditions examined showed significant associations with an increased body condition score, particularly those of 7 and above. These were dermatological conditions, atopic dermatitis, musculoskeletal conditions, arthritis, hypertension, respiratory conditions, asthma, oral conditions, diarrhoea, general and lower urinary tract conditions, ophthalmic conditions, diabetes mellitus and allergic conditions. Additionally, cats with body condition score of 8 or 9 had significantly higher odds for gastrointestinal conditions and upper urinary tract conditions when compared with cats with body condition score of 5. CLINICAL SIGNIFICANCE: As far as we know, this is the first study reporting positive associations of high body condition score with atopic dermatitis, hypertension, asthma, diarrhoea, ophthalmic conditions and allergic conditions in cats. A large number of positive associations between health conditions and high body condition score indicates that excess fat mass should be given a greater emphasis in preventive health care for cats.

Dietary restriction increases variability in longevity.

Nutritional environments, particularly those experienced during early life, are hypothesized to affect longevity. A recent cross-taxa meta-analysis found that, depending upon circumstance, average longevity may be increased or decreased by early-life dietary restriction. Unstudied are the effects of diet during development on among-individual variance in longevity. Here, we address this issue using emerging methods for meta-analysis of variance. We found that, in general, standard deviation (s.d.) in longevity is around 8% higher under early-life dietary restriction than a standard diet. The effects became especially profound when dietary insults were experienced prenatally (s.d. increased by 29%) and/or extended into adulthood (s.d. increased by 36.6%). Early-life dietary restriction may generate variance in longevity as a result of increased variance in resource acquisition or allocation, but the mechanisms underlying these largely overlooked patterns clearly warrant elucidation.

Discrepancy between the composition of some commercial cat foods and their package labelling and suitability for meeting nutritional requirements.

OBJECTIVE: To investigate if the label information and nutrient composition of commercial cat foods are accurate and compliant with the Australian Standard (AS 5812-2011) and if they meet the nutritional requirements of an adult cat. METHODS: A chemical analysis of 10 wet and 10 dry commercial cat foods labelled as 'nutritionally complete' for the adult cat was performed. The results were compared with the package composition values, the Australian Standard and the unique dietary requirements of the cat. In addition, the results of the chemical analysis were compared with the nutrient requirements published by the Association of the American Feed Control Officials and the National Research Council. RESULTS: When compared with the Australian Standard, 9 of the 20 cat foods did not adhere to their 'guaranteed analysis' and 8 did not adhere to the standards for nutrient composition. Also, various deficiencies and excesses of crude protein, crude fat, fatty acid and amino acid were observed in the majority of the cat foods. CONCLUSIONS: The results of this study highlight a need for an improved method of ensuring that label information and nutrient composition are accurate and comply with the Australian Standard (AS 5812-2011) to ensure the adult cat's unique dietary requirements are being met by commercial adult cat food.

Preferred natural food of breeding Kakapo is a high value source of calcium and vitamin D.

The Kakapo, a large NZ native parrot, is under severe threat of extinction. Kakapo breed only in years when the local podocarps, including rimu (Dacrydium cupressinum), are fruiting heavily, and the fruit are the preferred food both in the diet of breeding females and for provisioning chicks. Attempts to provide a supplementary food during years of poor fruit supply have failed to encourage breeding. Nutrient analysis of rimu berries reveals high calcium content (8.4mg/g dry matter) which would be essential for both egg shell production and the growing skeleton of the chick. Vitamin D is also critical for these processes and for the maintenance of calcium homeostasis, but the source of vitamin D for these nocturnal, ground-dwelling vegetarians is unknown. OBJECTIVE: To examine the vitamin D status of adult Kakapo, and to investigate the possibility that rimu berries provide vitamin D as well as calcium, thus differentiating them from the supplementary foods provided to date. METHOD: Previously collected and frozen serum from 10 adult birds (6 females, 4 males) was assayed for 25(OH)D3 and D2. Two batches of previously frozen rimu berries were analysed for vitamin D3 and D2. RESULTS: Vitamin D status of the 10 adult birds was very low; mean 4.9nmol/l, range 1-14nmol/l 25(OH)D3. No 25(OH)D2 was detected in any of the birds. High levels of D2 and moderate levels of D3 were found in the rimu berries. CONCLUSION: Traditionally it has been considered that the D3 isoform of this endogenously produced secosteroid is produced only in animals. However, D3 has been reported in the leaves of plants of the Solanacae family (tomato, potato, capsicum). The avian vitamin D receptor (VDR) is thought to have a much greater affinity for the D3 form. Therefore if rimu fruit are able to provide breeding Kakapo with D3, and are a plentiful source of calcium, they could be the perfect food package for breeding and nesting birds. Of wider importance, this finding challenges conventional understanding that D3 production is exclusive to animals, and that there are no high concentration food sources of vitamin D.

Little appetite for obesity: meta-analysis of the effects of maternal obesogenic diets on offspring food intake and body mass in rodents.

BACKGROUND: There is increasing recognition that maternal effects contribute to variation in individual food intake and metabolism. For example, many experimental studies on model animals have reported the effect of a maternal obesogenic diet during pregnancy on the appetite of offspring. However, the consistency of effects and the causes of variation among studies remain poorly understood. METHODS: After a systematic search for relevant publications, we selected 53 studies on rats and mice for a meta-analysis. We extracted and analysed data on the differences in food intake and body weight between offspring of dams fed obesogenic diets and dams fed standard diets during gestation. We used meta-regression to study predictors of the strength and direction of the effect sizes. RESULTS: We found that experimental offspring tended to eat more than control offspring but this difference was small and not statistically significant (0.198, 95% highest posterior density (HPD)=-0.118-0.627). However, offspring from dams on obesogenic diets were significantly heavier than offspring of control dams (0.591, 95% HPD=0.052-1.056). Meta-regression analysis revealed no significant influences of tested predictor variables (for example, use of choice vs no-choice maternal diet, offspring sex) on differences in offspring appetite. Dietary manipulations that extended into lactation had the largest effect on body weight. Subgroup analysis revealed that high protein to non-protein ratio of the maternal diet may promote increased body weight in experimental offspring in comparison with control offspring; low protein content in the maternal chow can have opposite effect. CONCLUSIONS: Exposure to maternal obesogenic diets in early life is not likely to result in a substantial change in offspring appetite. Nevertheless, we found an effect on offspring body weight, consistent with permanent alterations of offspring metabolism in response to maternal diet. Additionally, it appears that protein content of the obesogenic diet and timing of manipulation modulate the effects on offspring body weight in later life.

Protein leverage and energy intake.

Increased energy intakes are contributing to overweight and obesity. Growing evidence supports the role of protein appetite in driving excess intake when dietary protein is diluted (the protein leverage hypothesis). Understanding the interactions between dietary macronutrient balance and nutrient-specific appetite systems will be required for designing dietary interventions that work with, rather than against, basic regulatory physiology. Data were collected from 38 published experimental trials measuring ad libitum intake in subjects confined to menus differing in macronutrient composition. Collectively, these trials encompassed considerable variation in percent protein (spanning 8-54% of total energy), carbohydrate (1.6-72%) and fat (11-66%). The data provide an opportunity to describe the individual and interactive effects of dietary protein, carbohydrate and fat on the control of total energy intake. Percent dietary protein was negatively associated with total energy intake (F = 6.9, P < 0.0001) irrespective of whether carbohydrate (F = 0, P = 0.7) or fat (F = 0, P = 0.5) were the diluents of protein. The analysis strongly supports a role for protein leverage in lean, overweight and obese humans. A better appreciation of the targets and regulatory priorities for protein, carbohydrate and fat intake will inform the design of effective and health-promoting weight loss diets, food labelling policies, food production systems and regulatory frameworks.

Transgenerational effects of caloric restriction on appetite: a meta-analysis.

Maternal undernutrition can result in significant alterations to the post-natal offspring phenotype, including body size and behaviour. For example, maternal food restriction has been implicated in offspring hyperphagia, potentially causing increased weight gain and fat accumulation. This could result in obesity and other adverse long-term health effects in offspring. We investigated the link between maternal caloric restriction during gestation and offspring appetite by conducting the first meta-analysis on this topic using experimental data from mammalian laboratory models (i.e. rats and mice). We collected 89 effect sizes from 35 studies, together with relevant moderators. Our analysis revealed weak and statistically non-significant overall effect on offspring's appetite. However, we found that lower protein content of restricted diets is associated with higher food intake in female offspring. Importantly, we show that a main source of variation among studies arises from whether, and how, food intake was adjusted for body mass. This probably explains many of the contradictory results in the field. Based on our results, we recommend using allometric scaling of food intake to body mass in future studies.

Reproductive biology of an odacine labrid, Odax pullus.

The sexual ontogeny of butterfish Odax pullus was examined in the Hauraki Gulf of New Zealand through histological analysis of gonad material, size and age information and seasonal patterns of sexual maturation. The patterns of gonad development and schedules of male recruitment were established and sexual ontogeny of O. pullus was diagnosed as monandric protogyny, with all males developing from mature females after female-to-male sex reversal. All individuals underwent an immature female phase before maturing as functional females at 228·7-264·8 mm fork length (L(F) ) and at 1·1-1·5 years of age, and there was no evidence of a juvenile bisexual phase. Degenerating mature oogenic elements were found in the gonad lumen of individuals with developing spermatogenic tissue, providing histological evidence for functional protogyny. Sex change was estimated to occur at 359-379 mm L(F) and 2-3 years of age. The diagnosis of monandric protogyny for O. pullus coincided with the pattern of sexual ontogeny seen in the majority of labrids, particularly those of the same clade (tribe Hypsigenyini) and contrasted with that seen in a number of other temperate labrids. This study suggests that the protogynous mode of sexual development in O. pullus is likely to be lineage-specific, i.e. associated with the phylogeny of labrid sexual development, and is not constrained by environmental effects on the evolution of sex change in temperate regions.

Maternal preconceptional nutrition leads to variable fat deposition and gut dimensions of adult offspring mice (C57BL/6JBom).

BACKGROUND: Maternal nutrition during pregnancy or lactation may affect the chance of offspring becoming obese as adults, but little is known regarding the possible role of maternal nutrition before conception. In this study, we investigate how variable protein and carbohydrate content of the diet consumed before pregnancy affects fat deposition and gut dimensions of offspring mice. METHODS: Eight-week-old female mice (C57BL/6JBom) were fed isocaloric low protein (8.4% protein; LP), standard protein (21.5% protein; ST) or high protein (44.2% protein; HP) diets. After 8 weeks of feeding, females were mated and fed a standard laboratory chow diet (22.5% protein) throughout periods of mating, gestation, lactation and weaning. Offspring mice were fed the same standard diet up to 46 days of age. Then offspring were killed and measures of dissected fat deposits and of the digestive system were taken. RESULTS: Fat deposition of the offspring was significantly affected by preconceptional maternal nutrition and the effects differed between sexes. Male offspring deposited most fat when mothers were fed the LP diet, whereas female offspring deposited most fat when mothers were fed the ST diet. The mass and length of the digestive organs were affected by preconceptional maternal nutrition. Total gut from pyloric sphincter to anus was significantly shorter and dry mass was heavier in mice whose mothers were fed LP diets compared with offspring of mothers fed ST diets or HP diets. There was no significant effect of maternal nutrition on dry mass of the stomach or ceca. CONCLUSION: Our study shows that preconceptional nutrition can have important influence on several body features of offspring in mice, including body composition and dimensions of the digestive system.

The price of protein: combining evolutionary and economic analysis to understand excessive energy consumption.

Excessive weight gain appears, thermodynamically at least, straightforward: growing energy intake and/or falling energy expenditure create an energetic surplus, resulting in fat accumulation. The situation is, however, far more complex, with genetic, physiological, social, psychological and economic factors all implicated. Thus the causes of excessive weight gain remain difficult to disentangle. We combine two recent developments from different areas of nutrition research: the study of food prices in relation to energy content and the hypothesis that an evolved propensity to regulate protein intake more strongly than non-protein calories exerts powerful leverage on overall energy intake. We partition the energy content of a range of common supermarket foods, and show that increasing overall energy content only modestly raises the cost of foods, largely as a result of macronutrients having very different costs. Higher food prices are associated with higher protein content and lower carbohydrate content, whereas fat content was not significantly associated with food price. We show that the differential costs of energy from protein and carbohydrates may bias consumers towards diets high in carbohydrate energy, leading them to consume excessive energy to meet their dietary protein needs. We review evidence from physiology, evolution and economics that support our suggestion.

Flexible diet choice offsets protein costs of pathogen resistance in a caterpillar.

Mounting effective resistance against pathogens is costly in terms of energy and nutrients. However, it remains unexplored whether hosts can offset such costs by adjusting their dietary intake so as to recoup the specific resources involved. We test this possibility by experimentally challenging caterpillars (Spodoptera littoralis) with a highly virulent entomopathogen (nucleopolyhedrovirus), under dietary regimes varying in the content of protein and digestible carbohydrate. We found that dietary protein influenced both resistance to pathogen attack and constitutive immune function to a greater extent than did dietary carbohydrate, indicating higher protein costs of resistance than energy costs. Moreover, when allowed to self-compose their diet, insects surviving viral challenge increased their relative intake of protein compared with controls and those larvae dying of infection, thus demonstrating compensation for protein costs associated with resistance. These results suggest that the change in the host's nutritional demands to fight infection induces a compensatory shift in feeding behaviour.

Does Bertrand's rule apply to macronutrients?

It has been known for over a century that the dose-response curve for many micronutrients is non-monotonic, having an initial stage of increasing benefits with increased intake, followed by increasing costs as excesses become toxic. This phenomenon, termed Bertrand's rule, is widely assumed not to apply to caloric macronutrients. To date this assumption has been safe, owing to the considerable methodological challenges involved in coaxing animals to over-ingest macronutrients in a way that enables the effects of specific food components to be isolated. Here we report an experiment which overcomes these difficulties, to test whether the second phase (incurring costs with excessive intake) applies to carbohydrate intake by the generalist-feeding caterpillar Spodoptera littoralis. The results showed that excess carbohydrate intake caused increased mortality, thus extending Bertrand's rule to macronutrients.

Obesity: the protein leverage hypothesis.

The obesity epidemic is among the greatest public health challenges facing the modern world. Regarding dietary causes, most emphasis has been on changing patterns of fat and carbohydrate consumption. In contrast, the role of protein has largely been ignored, because (i) it typically comprises only approximately 15% of dietary energy, and (ii) protein intake has remained near constant within and across populations throughout the development of the obesity epidemic. We show that, paradoxically, these are precisely the two conditions that potentially provide protein with the leverage both to drive the obesity epidemic through its effects on food intake, and perhaps to assuage it. We formalize this hypothesis in a mathematical model. Some supporting epidemiological, experimental and animal data are presented, and predictions are made for future testing.

Nutrient balancing in grasshoppers: behavioural and physiological correlates of dietary breadth.

We examined correlates of nutrient balancing with dietary range by comparing diet selection and ingestive, post-ingestive and performance-related responses to macronutrient imbalance in two species of grasshopper. One of the two species, Locusta migratoria (the African migratory locust), is a specialist grass-feeder, while the other, Schistocerca gregaria (the desert locust), is a generalist herbivore that includes both grasses and forbs in its diet. In ad libitum conditions, both species composed a balanced intake of the two macronutrients protein and carbohydrate from nutritionally complementary synthetic foods, but the composition of the selected diet differed, with the generalist selecting more protein, but not carbohydrate, than the grass-specialist. The grass-specialist, by contrast, retained ingested nitrogen more efficiently on the ad libitum diets. When confined to nutritionally imbalanced foods, both species regulated ingestion in such a way as to mitigate excesses as well as deficits of the two nutrients. The responses were, however, distinct in the two species, with the generalist feeder ingesting greater excesses of protein than the specialist. The species also differed in their post-ingestive responses to ingested excesses of nutrient, with the generalist but not the specialist using protein-derived carbon as an energy source when fed carbohydrate-deficient foods. The generalist also retained a higher level of body protein when confined to protein-deficient diets. The data suggested one functional reason why the generalist species selected a diet with higher protein content in the ad libitum treatment because, when confined to the nutritionally imbalanced foods, development rate peaked on higher protein foods for the generalist compared with the specialist. Many aspects of these data agree with the prediction that generalist-feeding animals should show greater behavioural and physiological flexibility in their responses to nutrient imbalance than do specialists.

A comparison of nutritional regulation in solitarious- and gregarious-phase nymphs of the desert locust Schistocerca gregaria.

Nutritional regulatory responses were compared for the cryptic 'solitarious' and the conspicuously coloured, aggregating 'gregarious' phases of the desert locust Schistocerca gregaria. The desert locust has the genetic potential to exist in either phase, changing between them within a lifetime and epigenetically across generations. Our aim was to compare final-instar nymphs of the two phases with respect to key nutritional variables, including (i) points of regulated intake (the 'intake target') for protein and carbohydrate, (ii) the nature of trade-offs between over-eating nutrients in excess and under-eating those in deficit when fed nutritionally unbalanced foods, (iii) diet-related patterns of nutrient utilisation, and (iv) the performance consequences of eating nutritionally unbalanced diets. When provided with pairs of nutritionally unbalanced but complementary foods, both phases regulated their intake of protein and carbohydrate to a similar point. However, when confined to foods that were of unbalanced protein to carbohydrate ratio, gregarious nymphs ate more than solitarious insects. Both phases regulated protein growth, but gregarious insects did so to a lower adult body protein content and converted ingested protein to growth less efficiently. When fed a food high in carbohydrate and low in protein, gregarious nymphs deposited more body lipid and survived less well than did solitarious insects. Solitarious nymphs developed more quickly than gregarious nymphs except on the two most extremely unbalanced diets, on which development time was similar. The results are discussed with respect to the different nutritional ecologies of the two phases and used to develop the hypothesis that animals have evolved to trade-off the cost of eating excess of a nutritionally unbalanced diet against the probability of encountering foods of complementary composition in the future.

A geometric analysis of nutrient regulation in the generalist caterpillar Spodoptera littoralis (Boisduval).

Nutritional regulatory responses of the generalist caterpillar Spodoptera littoralis (Boisduval) were explored, in choice and no-choice experiments, using the Geometric Framework. In the choice experiment, newly moulted final instar larvae were provided with one of three protein-biased foods (PB-food: p35:c7, p28:c5.6 or p21:c4.2) and one of three equal protein-carbohydrate ratio foods (ER-food: p21:c21, p16.8:c16.8 or p12.6:c12.6). On five of the nine treatments, caterpillars independently regulated protein and carbohydrate intake to a mixture of 57 and 43%, respectively. However, when the concentration of the ER-food decreased and that of the paired PB-food increased, caterpillars progressively abandoned regulation and ate more of the PB-food. Despite these regulatory differences, performance (survivorship, growth and development) was similar across all nine treatments. In the no-choice experiment, caterpillars were given one of five foods (p35:c7, p28:c14, p21:c21, p14:c28 and p7:c35). Results indicated that caterpillars moved to a point in protein-carbohydrate space that was consistent with the Equal Distance Rule of compromise, a pattern previously predicted for generalist feeders. The insects on the two extreme foods, p35:c7 and p7:c35, showed reduced pupal mass and longer development, respectively. There was also strong evidence for post-ingestive regulation of nutrient utilisation, notably for protein.

Nutritional regulation in nymphs of the German cockroach, Blattella germanica.

Synthetic foods varying in protein-carbohydrate ratio and total nutrient concentration were used in food selection experiments to investigate the ingestive and post-ingestive regulation of macronutrients by male and female nymphs of the German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae). For both nutrient imbalance and food dilution, food ingestion varied between treatments with the effect that nutrient ingestion was regulated. However, this mechanism was insufficient to compensate for some food dilution treatments. In those cases, the regulation of protein intake was prioritised over that of carbohydrate intake, and two additional regulatory responses were seen. Firstly, cellulose digestion supplemented shortfalls in dietary soluble carbohydrates, and secondly the feeding period within the stadium was prolonged. These ingestive, post-ingestive and developmental responses were orchestrated in such a way that, in all treatments, nutrient gain approached similar levels, despite the variation in food properties.

Sex-specific differences in nitrogen intake and investment by feral and laboratory-cultured cockroaches.

We compared nutrient selection in a laboratory culture of the American cockroach (Periplaneta americana: Insecta, Blattodea) and a feral population which was founded by escapees from the culture approximately 14 generations prior to the study. In a first experiment, adult male and female cockroaches were provided with two nutritionally complementary synthetic foods, and thus allowed to select the protein and carbohydrate components of their diet independently. There were no differences in the amounts of carbohydrate eaten by the two populations. However, feral males ingested more protein than cultured males. In a second experiment, the construction of nitrogen budgets showed that the additional nitrogen ingested by feral males was allocated preferentially to accessory sex glands, rather than somatic tissue or excretion via the faeces. This suggests a possible role for sexual selection in the dietary difference between the strains. By contrast with males, there was no statistically significant difference in the amount of protein eaten by females of the two populations. However, feral females were found to have a higher density of bacterial endosymbionts than cultured females. Since these symbionts are involved in the synthesis of essential amino acids, this might account for greater reproductive output observed in a previous study in the feral compared with the culture females.

Assuaging nutritional complexity: a geometrical approach.

We have introduced a framework that enables the identification of the important elements in complex nutritional systems, and the quantification of the interactions among them. These interactions include those among the multiple constituents of the ingesta, as well as between behavioural (ingestive) and physiological (post-ingestive) components of nutritional homeostasis. The resulting descriptions provide a powerful means to generate and test hypotheses concerning the mechanisms, ecology and evolution of nutritional systems. We provide an overview of the key concepts involved in our scheme, and then introduce four examples in which the framework is used to develop and test hypotheses. In the first example we use comparative methods based on a data set of 117 insect species to test a prediction about the relationship between evolving an association with bacterial endosymbionts and the composition of the optimal diet. Second, using two species of locusts (a grass specialist and a generalist), we consider the relationship between an animal's diet breadth and the decision rules employed when feeding on foods containing suboptimal protein: carbohydrate values. Third, we introduce a mathematical model that predicts the dose-response properties of gustatory systems in the context of nutritional homeostasis. Finally, we consider the interaction between tannic acid and macronutrient balance in the diet of locusts.

Geometric analysis of macronutrient selection in the rat.

A conceptual framework is introduced which has been derived from work on insects. The scheme is intended to integrate studies of diet selection, regulation of amounts eaten, nutrient utilization, body composition and animal performance. Aspects of framework are illustrated with published data on macronutrient selection in the rat. An animal is viewed as moving through a multidimensional nutrient space, which is bounded by axes representing each required nutrient and within which lie optimal points of intake and nutrient allocation ("targets"). The aim is first to estimate the location of these functional optima experimentally, and then to interpret the responses of animals which are constrained from reaching them ("decisions of best compromise"). The framework can then be used to interpret data from animals reared under differing environmental conditions and to compare animals of differing developmental stage, genotype or nutritional state.