What do caribou eat? A review of the literature on caribou diet

Historically the study of diet caribou and reindeer (Rangifer tarandus (Gmelin, 1788)) has been specific to herds and few comprehensive circumpolar analyses of Rangifer diet exist. As a result, the importance of certain diet items may play an outsized role in the caribou diet zeitgeist, e.g., lichen. It is incumbent to challenge this notion and test the relevant importance of various diet items within the context of prevailing hypotheses. We provide a systematic overview of 30 caribou studies reporting caribou diet and test biologically relevant hypotheses about spatial and temporal dietary variation. Our results indicate that in the winter caribou primarily consume lichen, but in warmer seasons, and primary productivity is lower, caribou primarily consume graminoids and other vascular plants. In more productive environments, where caribou have more competitors and predators, consumption of lichen increased. Overall, our description of caribou diet reveals that caribou diet is highly variable, but in circumstances where they can consume vascular plants, they will. As climate change affects Boreal and Arctic ecosystems, the type and volume of food consumed by caribou has become an increasingly important focus for conservation and management of caribou.

DERMATITIS ULCERATIVA EN RATONES BALB/c Cmedc: REPORTE DE 3 CASOS

Ulcerative dermatitis (UD) is a common and spontaneous condition in mice. The disease is characterized by a pruritic skin lesion, pain and a progressive evolution that often results in ulcerations. Sex, environmental conditions, dietary variation, chronic inflammation, barbering and follicular dystrophy are some predisposing factors for the clinical disease development. The aim of this study was report 3 cases of UD in BALBc/Cmedc mice from Center for Comparative Medicine, gross and histopathological lesions were described, and a review about relevance of UD in laboratory mice was made. These cases were characterized by dermatitis, ulcerative and proliferative, chronic, moderate, with neutrophils, hemorrhage and a serocellular crust. Although initial lesions may be mild, lesions in UD typically are unresponsive to treatment and euthanasia is often warranted in severe cases. This is the reason why UD is an important clinical issue that often affects biomedical research by causing problems in mice health and premature removal of animal from laboratory studies.

Multiscale analysis reveals that diet-dependent midgut plasticity emerges from alterations in both stem cell niche coupling and enterocyte size

The gut is the primary interface between an animal and food, but how it adapts to qualitative dietary variation is poorly defined. We find that the Drosophila midgut plastically resizes following changes in dietary composition. A panel of nutrients collectively promote gut growth, which sugar opposes. Diet influences absolute and relative levels of enterocyte loss and stem cell proliferation, which together determine cell numbers. Diet also influences enterocyte size. A high sugar diet inhibits translation and uncouples intestinal stem cell proliferation from expression of niche-derived signals, but, surprisingly, rescuing these effects genetically was not sufficient to modify diet’s impact on midgut size. However, when stem cell proliferation was deficient, diet’s impact on enterocyte size was enhanced, and reducing enterocyte-autonomous TOR signaling was sufficient to attenuate diet-dependent midgut resizing. These data clarify the complex relationships between nutrition, epithelial dynamics, and cell size, and reveal a new mode of plastic, diet-dependent organ resizing.

Spring diet differs among age-sex classes in Atlas Barbary sheep (Ammotragus lervia lervia) in a fenced nature reserve, Morocco

Atlas Barbary sheep, Ammotragus lervia lervia, are the only wild caprinid of Northwest Africa. Some studies have investigated their feeding ecology, but there is no information on intraspecific dietary variation. Therefore, we determined the spring diet and its variation between age-sex classes in Atlas Barbary sheep within a fenced nature reserve in the Western High Atlas mountain range, Morocco. We used faecal microhistological analysis to assess diet composition based on a reference epidermis catalogue. The habitat was a highly diversified open mixed forest with 61 identified species (55 genera; 24 families). The herbaceous layer was dominated by grasses, mainly Stipa capensis. Atlas Barbary sheep revealed to be opportunistic grazers, consuming 44 forage species; grasses and forbs constituted 87% of the overall diet. There were significant intraspecific dietary differences. Rams showed a more diverse (42 species) and distinct diet compared to those of ewes (22 species) and juveniles (lambs + yearlings) (only 10 species). All sex-age classes were mostly grazers, adults feeding on grasses and forbs in similar proportions, whereas juveniles feeding basically on grasses (more than 70% of their diet) and almost no forbs. Ewes and juveniles feed on browse at a higher proportion than rams do. Our findings would be useful for the restoration and management of the habitat and food resources within the reserve.

Disturbance cue communication is shaped by emitter diet and receiver background risk in Trinidadian guppies

In animal communication systems, individuals that detect a cue (i.e., ‘receivers’) are often influenced by characteristics of the cue emitter. For instance, in many species, receivers avoid chemical cues that are released by emitters experiencing disturbance. These chemical ‘disturbance cues’ appear to benefit receivers by warning them about nearby danger, such as a predator’s approach. While the active ingredients in disturbance cues have been largely unexplored, by-products of metabolized protein are thought to play a role for some species. If so, the content (quality) and volume (quantity) of the emitter’s diet should affect their disturbance cues, thus altering how receivers perceive the cues and respond. Guppies Poecilia reticulata are a species known to discriminate among disturbance cues from different types of donors, but dietary variation has yet to be explored. In this study, we found evidence that diet quality and quantity can affect disturbance cues released by guppy emitters (i.e., experimental ‘donors’). Receivers discriminated between donor cue treatments, responding more strongly to cues from donors fed a protein-rich bloodworm diet (experiment 1), as well as an overall larger diet (experiment 2). We also found that receivers exposed to higher background risk were more sensitive to disturbance cue variation, with the strongest avoidance responses displayed by high-risk receivers toward disturbance cues from donors fed the high-quality diet. Therefore, diet, and perhaps protein specifically, affects either the concentration or composition of disturbance cues released by guppies. Such variation may be important in information signalling in social species like the guppy.

Relationship of Food Variations, Snack Food, and Physical Activities with the Nutrition Status of Students in Labuhan Batu District

Background: One group of school-age children has nutritional problems. The problem of excess nutrients can affect body function, while a nutrient deficiency can cause impaired body growth and maturity of the reproductive organ system. Also, daily nutritional deficiencies can cause a lack of concentration in learning. Purpose: To determine the effect of food consumption patterns on nutritional status. Method: The research design used was observational with a cross-sectional study approach. This research was conducted at SMP Negeri 3 Satu Atap Batu Bujur, West Bilah Subdistrict, Labuhan Batu Regency, North Sumatra Province with a research sample of 78 students consisting of class VII and VIII aged 13-15 years. The sampling technique in this research is using the total sampling method. Data analysis was performed univariate and bivariate using the Chi-Square test. Results: dietary variation was associated with nutritional status with a p-value (0.010). Snack food was related to nutritional status with a p-value (0.45). Physical activity is related to nutritional status with a p-value (0.030). Conclusion: There is a correlation between dietary variation, snack food, and physical activity with nutritional status among students. It is recommended that students keep their food consumption and physical activity in accordance with nutritional needs.Keywords: Food Variation, Snack Food, Physical Activity, Nutritional Status.