Lucille Alexander

Personality in captivity reflects personality in the wild

To investigate the ecological significance of personality, researchers generally measure behavioural traits in captivity. Whether behaviour in captivity is analogous to behaviour in the wild, however, is seldom tested. We compared individual behaviour between captivity and the wild in blue tits, Cyanistes caeruleus. Over two winters, 125 blue tits were briefly brought into captivity to measure exploratory tendency and neophobia using variants of standard personality assays. Each was then released, fitted with a passive integrated transponder. Using an electronic monitoring system, we then recorded individuals’ use of feeders as they foraged in the wild. We used variation in the discovery of new feeders to score 91 birds for exploratory tendency in the wild. At eight permanent feeding stations, 78 birds were assayed for neophobia in the wild. Behavioural variation in the captive personality trials was independent of permanent (e.g. sex) and nonpermanent (e.g. condition or weather) sources of betweenindividual variation at capture. Individual exploratory tendency and neophobia were consistent and repeatable in captivity, and analogous traits were repeatable in the wild; thus all constituted personality traits in the blue tit. Exploratory tendency and neophobia were not correlated with each other, in either the captive or the wild context. Therefore they are independent traits in blue tits, in contrast to many species. Finally, exploratory tendency and neophobia measured in captivity positively predicted the analogous traits measured in the wild. Reflecting differences in the use of feeding opportunities, personality in captivity therefore revealed relevant differences in foraging behaviour between individuals.

The effects of short-term antioxidant supplementation on oxidative stress and flight performance in adult budgerigars Melopsittacus undulatus

SUMMARY Antioxidants are known to play an important role in quenching reactive oxygen species (ROS), thus ameliorating oxidative stress. Since increased metabolism associated with exercise can increase oxidative stress, dietary antioxidants may be a limiting factor in determining aspects of physical performance. Here we tested whether oxidative stress associated with flight exercise of captive adult budgerigars, Melopsittacus undulatus differed after they received a diet containing either enhanced (EQ) or reduced levels (RQ) of a nutritional supplement (Nutrivit®) rich in antioxidants for 4 weeks. We also assessed differences in take-off escape time, a potential fitness-determining physiological capability. Oxidative stress was measured in two ways: comet assay to measure DNA damage; and analysis of malondialdehyde (MDA), a by-product of lipid peroxidation. Flight exercise appeared to increase oxidative stress. Moreover, birds had a higher percentage of intact DNA (fewer alkali labile sites) in one comet measure and lower levels of MDA after an EQ diet than after an RQ diet. We found no difference in flight performance between the two diets. Our results suggested that birds exerted maximum effort in escape flights, regardless of diet. However, this was at a cost of increased oxidative stress post-flight when on a reduced quality diet, but not when on an enhanced, antioxidant-rich diet. We suggest that dietary antioxidants may prove important in reducing exercise-related costs through multiple physiological pathways. Further work is necessary to fully understand the effects of antioxidants and oxidative stress on exercise performance in the longer term.

Dietary antioxidants, lipid peroxidation and plumage colouration in nestling blue tits Cyanistes caeruleus.

Carotenoid pigments are responsible for many of the red, yellow and orange plumage and integument traits seen in birds. One idea suggests that since carotenoids can act as antioxidants, carotenoid-mediated colouration may reveal an individuals ability to resist oxidative damage. In fact, there is currently very little information on the effects of most dietary-acquired antioxidants on oxidative stress in wild birds. Here, we assessed the impacts on oxidative damage, plasma antioxidants, growth and plumage colouration after supplementing nestling blue tits Cyanistes caeruleus with one of three diets; control, carotenoid treatment or α-tocopherol treatment. Oxidative damage was assessed by HPLC analysis of plasma levels of malondialdehyde (MDA), a by-product of lipid peroxidation. Contrary to predictions, we found no differences in oxidative damage, plumage colouration or growth rate between treatment groups. Although plasma lutein concentrations were significantly raised in carotenoid-fed chicks, α-tocopherol treatment had no effect on concentrations of plasma α-tocopherol compared with controls. Interestingly, we found that faster growing chicks had higher levels of oxidative damage than slower growing birds, independent of treatment, body mass and condition at fledging. Moreover, the chromatic signal of the chest plumage of birds was positively correlated with levels of MDA but not plasma antioxidant concentrations: more colourful nestlings had higher oxidative damage than less colourful individuals. Thus, increased carotenoid-mediated plumage does not reveal resistance to oxidative damage for nestling blue tits, but may indicate costs paid, in terms of oxidative damage. Our results indicate that the trade-offs between competing physiological systems for dietary antioxidants are likely to be complex in rapidly developing birds. Moreover, interpreting the biological relevance of different biomarkers of antioxidant status represents a challenge for evolutionary ecology.

Oxidative profile varies with personality in European greenfinches

SUMMARY Where behavioural responses differ consistently between individuals, this is termed ‘personality’. There is the suggestion, but with little supporting data, that personality traits reflect underlying variation in physiology. Here, we tested whether greenfinches Carduelis chloris differing in personality traits differed in various plasma indices of oxidative profile: antioxidant capacity (OXY), pro-oxidant status (reactive oxygen metabolites, ROMs), oxidative stress (OS) and an end-product of oxidative damage: malondialdehyde (MDA). We measured two personality traits: neophobia (latency to approach food near novel objects) and object exploration (latency to approach novel objects). These traits were uncorrelated. ROMs, OXY, OS and MDA were also uncorrelated with each other. Highly neophobic birds had lower OXY, higher ROMs and higher OS than less neophobic birds. Fast exploring birds had higher OXY than slow explorers, but did not differ in ROMs or OS. Variation in MDA was described by a quadratic relationship with neophobia: birds with extremely high or low neophobia had lower MDA than birds with intermediate neophobia, despite highly neophobic birds exhibiting lower OS than intermediately neophobic birds. Additively in that model, fast explorers had lower MDA than slower explorers. To conclude: first, personality types can differ in oxidative profile. Second, although physiological differences (e.g. hormonal stress responsiveness) between personality types generally range along a linear continuum, physiological costs may not. Finally, relationships with oxidative profile differed between neophobia and object exploration. Understanding how oxidative profile and thus physiological costs vary within and between personality traits may explain how differences in personality traits can predict fitness.

The Maillard reaction and pet food processing: effects on nutritive value and pet health

The Maillard reaction, which can occur during heat processing of pet foods or ingredients, is known to reduce the bioavailability of essential amino acids such as lysine due to the formation of early and advanced Maillard reaction products (MRP) that are unavailable for utilisation by the body. Determination of the difference between total and reactive lysine by chemical methods provides an indication of the amount of early MRP present in foods, feeds and ingredients. Previous research reported that the difference between total and reactive lysine in pet foods can be up to 61.8%, and foods for growing dogs may be at risk of supplying less lysine than the animal may require. The endogenous analogues of advanced MRP, advanced glycation endproducts, have been associated with age-related diseases in humans, such as diabetes and impaired renal function. It is unknown to what extent advanced MRP are present in pet foods, and if dietary MRP can be associated with the development of diseases such as diabetes and impaired renal function in pet animals. Avoidance of ingredients with high levels of MRP and processing conditions known to favour the Maillard reaction may be useful strategies to prevent the formation of MRP in manufactured pet food. Future work should further focus on understanding the effects of ingredient choice and processing conditions on the formation of early and advanced MRP, and possible effects on animal health.

Effects of neutering on food intake, body weight and body composition in growing female kittens

To understand the effects of neutering on food intake, body weight (BW) and body composition in kittens, data from an unrelated study were subjected to post hoc analysis. A total of twelve pairs of 11-week-old female littermates were randomly assigned to either a neutered group (neutered at 19 weeks old) or an entire group (kept entire) and offered free access to a dry diet until the age of 1 year. Neutered kittens exhibited increased food intake and increased BW after neutering (both P < 0.00 001). Food intake (per kg BW) peaked 10 weeks after neutering; the mean intake of neutered kittens was 17 (95 % CI 8, 27) % more than entire littermates (P = 0.00 014). The intake was then reduced until there was no significant difference between the groups 18 weeks post-neutering. By 52 weeks of age, the neutered kittens were 24 (95 % CI 11, 39) % heavier than entire littermates (P < 0.0001) with a body condition score (BCS) 16.6 (95 % CI 0.9, 34.8) % higher (P = 0.0028). Neutered kittens continued to grow significantly fatter after neutering (all P < 0.0014), while entire kittens showed no significant change after 18 weeks of age. As neutered kittens consumed similar amounts of energy to their entire littermates from 18 weeks post-neutering, while their BW, BCS and percentage fat continued to increase, we suggest that neutered kittens have a reduced metabolisable energy requirement, and should therefore be fed to maintain an ideal BCS rather than ad libitum. Moreover, to maintain an ideal BCS, entire kittens consumed 93 (95 % CI 87, 100) % of their theoretical intake at 26 weeks of age, and 79 (95 % CI 72, 87) % at 52 weeks of age, suggesting that the current energy recommendation is inappropriate for these kittens.

Quantitation of Maillard reaction products in commercially available pet foods.

During processing of pet food, the Maillard reaction occurs, which reduces the bioavailability of essential amino acids such as lysine and results in the formation of advanced Maillard reaction products (MRPs). The aim of this study was to quantitate MRPs (fructoselysine (FL), carboxymethyllysine (CML), hydroxymethylfurfural (HMF)) and the cross-link lysinoalanine (LAL) in commercial pet foods. Sixty-seven extruded, canned, and pelleted dog and cat foods for growth and maintenance were analyzed using UPLC-MS. Canned pet foods contained on average the most FL, CML, and HMF (4534, 37, and 1417 mg/kg dry matter, respectively) followed by pelleted and extruded foods. Average daily intake (mg/kg body weight(0.75)) of HMF is 122 times higher for dogs and 38 times higher for cats than average intake for adult humans. As commercial pet foods are most often the only source of food for dogs and cats, future research focus should be on the bioavailability and long-term health implications of MRP consumption by dogs and cats.

Theoretical evaluation of risk for nutritional deficiency with caloric restriction in dogs

Background: Risk of nutrient deficiency in dogs during caloric restriction is not currently known, while obesity is a growing concern. Objectives: To determine nutrients that might require further evaluation for the risk of deficiency during caloric restriction. Animals and methods: Five commercially available canine diets, representing a range of caloric density (2900–4240 kcal/kg metabolizable energy), were assessed for potential nutrient inadequacy if fed to a hypothetical overweight dog. Caloric density and typical nutrient analysis for protein, amino acids, fat, fatty acids, minerals, and vitamins were obtained from the manufacturer. Nutrient intake was calculated using ideal body weight for caloric intakes including 87, 79, 70, 61 and 52 kcal/kg0.75 and compared with National Research Council recommended nutrient allowances (NRC-RA) for ideal weight. Results: No diets were less than NRC-RA when compared to NRC-RA (/1000 kcal). The five evaluated diets varied in terms of which nutrients were less than NRC-RA and the degree of restriction required for this to occur. All diets had at least one essential nutrient less than NRC-RA at 79 kcal/kg0.75/day and multiple nutrients less than NRC-RA at 70 kcal/kg0.75/day. Choline and selenium were the nutrients most often affected by caloric restriction but others were less than the NRC-RA with caloric restriction. Conclusions: Further research is needed to determine actual nutrient requirements in overweight dogs, and whether clinical nutrient deficiencies actually arise in vivo. Clinical importance: Weight loss plans for overweight dogs (particularly those with very low-energy requirements) should include consideration for nutrient adequacy.

The Influence of Feeding Frequency on Growth and Body Condition of the Common Goldfish (Carassius auratus)

The optimal frequency for feeding ornamental fish species has yet to be clearly defined and this has led to uncertainty in the feeding routines used by many aquarists. Both overand underfeeding can be detrimental to the health of the fish and may cause a marked deterioration in water quality, reduced weight, poor food utilization, and increased susceptibility to infection. Consequently, specific growth rates and the efficiency of feed conversion can be directly related to feed ration and frequency. Therefore, it is important to be able to predict the most favorable feeding frequency relative to the species and size of fish. Although it is often postulated that feeding ornamental fish little and often throughout the day will result in more efficient feed utilization, research has not yet been conducted to validate this hypothesis. Published literature on frequency of feeding ornamental fish is limited when compared with that available from cultured fish species. Data from aquaculture research is commonly extrapolated and applied to ornamental species, which often proves to be unsatisfactory because of the differences in fish species and variation in diet formulations. In addition, the majority of research has focused on feeding fish to satiation, measuring the food intake, and linking this to growth performance and utilization. Research conducted with the ornamental Red Swordtail (Xiphophorus helleri) indicated that feeding 2 meals/d (where a meal is defined as providing food until fish stop eating [the point of satiation]) resulted in the greatest growth and reproductive success of this species in a cultured system, when compared with 4 alternative feeding regimens (1 meal in 3 d, 1 meal in 2 d, 1 meal/d, and 2 meals/d) (1). Further investigations by the same researchers using the Siamese Fighting Fish (Betta splendens. Regan) showed that 2 meals/d fed to satiation elicited maximum growth and reproductive output for this ornamental fish species when compared with 1 meal in 3 d, 1 meal in 2 d, 1 meal/d, and 3 meals/d (2). Additional research on commercially cultured fish species such as the Black Rockfish (Sebastes schlegeli) suggested that feeding to satiation once a day resulted in optimum growth and food utilization when compared with 1 meal every 2 d or 2 meals/d (3). In addition, juvenile Atlantic Halibut (Hippoglossus hippoglossus) displayed improved growth rates when fed to satiation 5 times/d, compared with 1/d (4), and African Catfish (Clarias gariepinus) exhibited greater growth rates when fed to satiation twice compared with 3 times/d (5). In one study where a set amount of food was offered, Giberson and Litvak (6) established that Shortnose Sturgeon (Acipenser brevirostrum) grew significantly better when offered a food ration of 3% of the tank biomass divided into 4 or 8 feedings/d compared to one. However, in the same study, growth and feeding efficiencies of Atlantic Sturgeon (Acipenser oxyrinchus) were unaffected by the frequency of feeding. Currently there appear to be no data available that directly relates feeding frequency to growth and efficiency of food utilization in the Common Goldfish (Carassius auratus). However, the closely related subspecies, Gibel Carp (Carassius auratus gibelio), exhibited significant increases in growth rate and feed efficiency when feeding frequency increased from 2 to 3, 4, 12, and 24 feedings/d, with the authors recommending an optimal feeding frequency of 24 meals/d for this species (7). However, fish were juvenile and fed to satiation, confirming that feeding frequency in part is a function of fish size, with larval and juvenile fish needing to eat more frequently because of their high energy demands. This current study aimed to assess the effects of feeding a set amount of food at a variety of meal frequencies on growth parameters of the Common Goldfish (Carassius auratus) and to identify the optimum number of feeds/d to maximize utilization of the food ration. 1 Published in a supplement to The Journal of Nutrition. Presented as part of The WALTHAM International Nutritional Sciences Symposium: Innovations in Companion Animal Nutrition, held in Washington, DC, September 15–18, 2005. This conference was supported by The WALTHAM Centre for Pet Nutrition and organized in collaboration with the University of California, Davis, and Cornell University. This publication was supported by The WALTHAM Centre for Pet Nutrition. Guest editors for this symposium were D’Ann Finley, Francis A. Kallfelz, James G. Morris, and Quinton R. Rogers. Guest editor disclosure: expenses for the editors to travel to the symposium and honoraria were paid by The WALTHAM Centre for Pet Nutrition. 2 Author disclosure: no relationships to disclose. 3 To whom correspondence should be addressed. E-mail: abigail.stevenson@ eu.effem.com.

Colour cues or spatial cues? Context-dependent preferences in the European greenfinch (Carduelis chloris).

Using featural cues such as colour to identify ephemeral food can increase foraging efficiency. Featural cues may change over time however; therefore, animals should use spatial cues to relocate food that occurs in a temporally stable position. We tested this hypothesis by measuring the cue preferences of captive greenfinches Carduelis chloris when relocating food hidden in a foraging tray. In these standardised associative learning trials, greenfinches favoured colour cues when returning to a foraging context that they had encountered before only once (“one-trial test”) but switched to spatial cues when they had encountered that scenario on ten previous occasions (“repeated-trial test”). We suggest that repeated encounters generated a context in which individuals had a prior expectation of temporal stability, and hence context-dependent cue selection. Next, we trained birds to find food in the absence of colour cues but tested them in the presence of visual distracters. Birds were able to learn spatial cues after one encounter, but only when visual distracters were identical in colouration. When a colourful distracter was present in the test phase, cue selection was random. Unlike the first one-trial test, birds were not biased towards this colourful visual distracter. Together, these results suggest that greenfinches are able to learn both cue types, colour cue biases represent learning, not simply distraction, and spatial cues are favoured over colour cues only in temporally stable contexts.