Trace Element Imbalance in Vegetation as a Threat to Free Ranging Cattle in the Gilgel Gibe Valley, Ethiopia

As in many tropical countries, natural pastures are the main source of nutrients for cattle in Ethiopia. However, there is limited information available with regard to trace element concentrations in Ethiopian forages. In this study, 58 plants were sampled in the Gilgel Gibe valley based on the observed ingestion by zebu cattle (Bos indicus) herds, grazing at different elevation and soil types, and analysed for copper (Cu), cobalt (Co), iron (Fe), molybdenum (Mo), manganese (Mn), sulfur (S), selenium (Se) and zinc (Zn). The effect of elevation, soil type and plant type on the above trace element concentrations was investigated. Deficient Cu concentrations were present in 71% of samples. Plant samples contained at least marginally antagonistic concentrations of Mo, S and Fe towards Cu in 36, 48 and 88% of cases respectively, and deficient Se and Zn concentrations in 57 and 45% of cases respectively. For Mn and Zn, plant concentrations differed according to elevation region. Plants on Nitisol-Acrisol-Ferralsol associations contained higher amounts of Fe than on Planosol-Vertisol associations. Concentrations of Cu and S were higher in herbaceous and woody plants than in grasses and crop resides, whereas concentrations of Co were higher in herbaceous than in other plant types. Differences between plant types were also present for Fe. Overall, micro mineral deficiency is very likely to develop in cattle ranging at the studied area. Plant mineral concentrations were affected by a variety of factors, such as elevation, soil type and plant group, calling for a nuanced assessment of plant survey results

Tolerance and safety evaluation of N, N-dimethylglycine, a naturally occurring organic compound, as a feed additive in broiler diets

N,N-dimethylglycine (DMG) is a tertiary amino acid that naturally occurs as an intermediate metabolite in choline-to-glycine metabolism. The objective of the present trial was to evaluate tolerance, safety and bioaccumulation of dietary DMG in broilers when supplemented at 1 g and 10 g Na-DMG/kg. A feeding trial was conducted using 480 1-d-old broiler chicks that were randomly allocated to twenty-four pens and fed one of three test diets added with 0, 1 or 10 g Na-DMG/kg during a 39 d growth period. Production performance was recorded to assess tolerance and efficacy of the supplement. At the end of the trial, toxicity was evaluated by means of haematology, plasma biochemistry and histopathology of liver, kidney and heart (n 12), whereas bioaccumulation was assessed on breast meat, liver, blood, kidney and adipose tissue (n 8). Carcass traits were similar between the control and 1 g Na-DMG/kg feed groups (P.0·05), but the feed:gain ratio was significantly improved at 1 g Na-DMG/kg feed compared with the control or the 10-fold dose (P¼0·008). Histological examinations showed no pathological effects and results of haematology and plasma biochemistry revealed similar values between the test groups (P.0·05). Bioaccumulation occurred at the 10-fold dose, but the resulting DMG content in breast meat was comparable with, for instance, wheat bran and much lower than uncooked spinach. In conclusion, DMG at 1 g Na-DMG/kg improved the feed:gain ratio in broilers without DMG being accumulated in consumer parts. Furthermore, dietary supplementation with DMG up to 10 g Na-DMG/kg did not induce toxicity or impaired performance in broilers

The uneven weight distribution between predators and prey: Comparing gut fill between terrestrial herbivores and carnivores

The general observation that secondary consumers ingest highly digestible food and have simple short guts and small abdominal cavities intuitively results in the assumption that mammalian carnivores carry less digesta in their gut compared to herbivores. Due to logistic constraints, this assumption has not been tested quantitatively so far. In this contribution, we estimated the dry matter gut contents (DMC) for 25 species of the order Carnivora (including two strictly herbivorous ones, the giant and the red panda) using the physical ‘Occupancy Principle’, based on a literature data collection on dry matter intake (DMI), apparent dry matter digestibility (aD DM) and retention time (RT), and compared the results to an existing collection for herbivores. Scaling exponents with body mass (BM) for both carnivores and herbivores were in the same range with DMI ~ BM0.75; aD DM ~ BM0; RT ~ BM0.11 and DMC ~ BM0.88. The trophic level (carnivore vs herbivore) significantly affected all digestive physiology parameters except for RT. Numerically, the carnivore DMI level reached 77%, the RT 32% and DMC only 29% of the corresponding herbivore values, whereas the herbivore aD DM only reached 82% of that of carnivores. Thus, we quantitatively show that carnivores carry less inert mass or gut content compared to herbivores, which putatively benefits them in predator-prey interactions and might have contributed to the evolution towards unguligradism in herbivores. As expected, the two panda species appeared as outliers in the dataset with low aD DM and RT for a herbivore but extremely high DMI values, resulting in DMC in the lower part of the herbivore range. Whereas the difference in DMI and DMC scaling in herbivores might allow larger herbivores to compensate for lower diet quality by ingesting more, this difference may allow larger carnivores not to go for less digestible prey parts, but mainly to increase meal intervals, i.e. not having to hunt on a daily basis

Copper Status of Free Ranging Cattle: What’s Hidden Behind? A Pilot Study at the Gilgel Gibe Catchment, Ethiopia

Copper (Cu) deficiency is known to be a major risk for cattle health and production. The widespread problem is due to low absorption rates in the rumen, low Cu concentrations in the natural diet and the presence of dietary Cu antagonists, such as S, Mo and Fe (Suttle 2010). Cattle in the tropics are even more prone to shortage of this mineral, given that the animals are often extensively kept and largely dependent on natural pasture for mineral supply (McDowell and Arthington, 2005). More specifically, in Ethiopia, Cu deficiency was previously described in zebu (Bos indicus) cattle by several authors (e.g. Dermauw et al.). Similar to other minerals, Cu is part of the soil-plant-animal chain, with many factors influencing Cu concentrations at every level. In our study, the overall goal was to investigate the possible influence of certain environment and management factors on dietary concentrations of Cu and antagonists and Cu status in free ranging cattle

Nutrient intake and its possible drivers in free-ranging European brown bears (Ursus arctos arctos)

The dietary nutrient profile has metabolic significance and possibly contributes to species' foraging behavior. The brown bear (Ursus arctos) was used as a model species for which dietary ingredient and nutrient concentrations as well as nutrient ratios were determined annually, seasonally and per reproductive class. Brown bears had a vertebrate-and-ant-dominated diet in spring and early summer and a berry-dominated diet in fall, which translated into protein-rich and carbohydrate-rich diets, respectively. Fiber concentrations appeared constant over time and averaged at 25% of dry matter intake. Dietary ingredient proportions differed between reproductive classes; however, these differences did not translate into a difference in dietary nutrient concentrations, suggesting that bears manage to maintain similar nutrient profiles with selection of different ingredients. In terms of nutrient ratios, the dietary protein to non-protein ratio, considered optimal at around 0.2 (on metabolizable energy basis), averaged around 0.2 in this study in fall and around 0.8 in spring and summer. We introduced the minimal non-fat to fat ratio necessary for efficient maintenance metabolism. This ratio varied across seasons but never fell beneath the theoretically estimated minimum to ensure metabolic efficiency. This population thus managed to ingest diets that never exerted a lack of glucogenic substrate, suggesting that metabolic efficiency may either be a driver of active diet selection or that natural resources available to bears did not constitute a constraint in this respect. Given the considerable proportion of fiber in the diet of brown bears, the relevance of this nutrient and its role in foraging behavior might be underestimated

Do ingredient and nutrient intake reveal individual dietary specialization in an omnivorous carnivore, the brown bear?

Generalist populations often harbor individual dietary specialists. Whether using a narrower set of resources than the population (= specialization) affects specialists' nutrient intake remains underexplored. We evaluated variation in ingredient and nutrient specialization in a European brown bear Ursus arctos population via the Proportional Similarity Index (PSi, from 0 = highly specialized to 1 = not specialized) and assessed associations of specialization with year, season and reproductive class. Different methodologies concerning the organization of raw data for PSi calculations were evaluated (i.e. the resolution of diet compositional data (feces vs the average of all feces per individual) and temporal restrictions for the population (year‐round vs within‐season). Overall, a tendency for ingredient specialization (PSi 0.37 ± 0.14) and absence of nutrient specialization (PSi 0.79 ± 0.10) was observed. Ingredient specialization was mainly influenced by the proportion of berries, graminoids, oats and moose in the diet. Annual, seasonal and reproductive class effects were moderate and did not strongly affect PSi for both ingredients and nutrients. Organizing diet compositional data from a ‘feces resolution' to ‘individual resolution' decreased specialization. Changing the comparative population in PSi calculations from ‘all‐year‐round' to ‘within year and season' also resulted in less pronounced specialization. The degree of specialization was not caused by individuals exhibiting consistent ingredient preferences over the years (low repeatability of PSi) except in spring. Our results suggested absence of nutrient specialization and mild ingredient specialization, which appeared to be an outcome of the ecological circumstances rather than specific individual traits. Additionally, we demonstrated that the methods applied can have substantial influence for the calculation of specialization indices

Colouration in amphibians as a reflection of nutritional status : the case of tree frogs in Costa Rica

Colouration has been considered a cue for mating success in many species; ornaments in males often are related to carotenoid mobilization towards feathers and/or skin and can signal general health and nutrition status. However, there are several factors that can also link with status, such as physiological blood parameters and body condition, but there is not substantial evidence which supports the existence of these relationships and interactions in anurans. This study evaluated how body score and blood values interact with colouration in free-range Agalychnis callidryas and Agalychnis annae males. We found significant associations between body condition and plasmatic proteins and haematocrit, as well as between body condition and colour values from the chromaticity diagram. We also demonstrated that there is a significant relation between the glucose and plasmatic protein values that were reflected in the ventral colours of the animals, and haematocrit inversely affected most of those colour values. Significant differences were found between species as well as between populations of A. callidryas, suggesting that despite colour variation, there are also biochemical differences within animals from the same species located in different regions. These data provide information on underlying factors for colouration of male tree frogs in nature, provide insights about the dynamics of several nutrients in the amphibian model and how this could affect the reproductive output of the animals