Rythme nycthéméral de la sécrétion de mélatonine chez le dromadaire (Camelus dromedarius)

La mélatonine, une hormone secrétée par la glande pinéale, a été dosée sur trois chamelles vivant dans le Sud de la France. Comme pour les autres espèces domestiques, les résultats montrent qu'il existe un rythme nycthéméral de la sécrétion de cette hormone chez le dromadaire (Camelus dromedarius). (Résumé d'auteur

Camelids and sustainable development

Face to the global changes and new climatic constraints, the camel farming is confronted to new challenges, first to contribute to the “livestock revolution” (for reaching the requirements of a growing human population), especially in remote places of arid and mountainous areas, and in the same time to satisfy the necessity of sustainable development for the future generation. The current trends of the camelid farming systems in the world (settlement, intensification, market integration, territorial expanding, emerging diseases) question the scientists and the developers on the right ways for a sustainable development. Several aspects are discussed in the present paper: (i) the assessment of the contribution of camelids in the greenhouse gas emission, in relationships with the camel demography, (ii) the assessment and preservation of the camelid biodiversity, (ii) the assessment of the changes in the animal metabolism and in the environment management face to the intensification process, (iv) the control of the transboundary diseases in a population marked by mobility, and (v) the future of the social role of camelid in the more and more urbanized world.(Résumé d'auteur

Camel Anatomy; More Than Just a Hump

The one-humped camel (Camelus dromedarius) is capable of living in extreme, arid environments due to its numerous anatomical adaptations. Its modified features of the muscular system, integument, skeletal system, and several internal organs allow this animal to survive in such harsh environmental conditions. Many of these adaptations allow for conservation of energy and water as well as improvement of locomotion to acquire scarce resources. In this paper we will look more closely at some of these adaptations and determine their function in promoting the survival and reproduction of the one-humped camel in desert environments

Low milk cholesterol in camel milk: true or not?

Many authors argue that camel milk contains less cholesterol than cow milk while other reported the reverse. To compare the cholesterol content in camel and cow milk in similar farming conditions and to assess the impact of short underfeeding on cholesterol concentration in milk and serum, seven cows and seven camels were sampled (milk and blood) at the middle of lactation at morning and evening milking, then two weeks after distribution of low energy-protein diet, another sampling was achieved. Cholesterol content in camel milk (5.64 +- 3.18 mg 100g-1) was lower than in cow (8.51 +- 9.07 mg 100g-1), but the difference was not significant. Moreover, the ratio cholesterol/fat was similar in the two species (225 +- 125 mg 100g-1 fat in camel and 211 +- 142.4 mg 100g-1 fat in cow). Serum cholesterol concentration was significantly higher in cow (227.8 +- 60.5 vs 106.4 +- 28.9 mg 100mL-1). There was significant difference between morning and evening milking in milk fat composition and concentrations in cholesterol. The present study showed that cholesterol concentration in camel serum is lower than in cow in similar feeding and environmental conditions, but further researches are needed to demonstrate the relationship between feeding and cholesterol content in camel milk. (Résumé d'auteur

Seasonal variation of 25-hydroxyvitamin D3 levels in meat of Moroccan onehumped dromedary camels (Camelus dromedaries)

In human, vitamin D which derives from the action of sunlight in the skin and dietary intake is of great importance for health, and may be influenced by the season. In arid and semi-arid regions, camel meat is a good source of high- quality nutrition with less fat and significant health benefits. The aims of this investigation was to analysis the seasonal variation the 25-hydroxyvitamin D3(25-OH-D3) amounts in meat and serum of camels. In municipal slaughterhouse of Casablanca, samples of blood, Musculus oblicus externus abdominis, liver and kidney were collected in winter and summer from twelve 4-7-year-old male camels. Levels of 25-OH-D3 were analyzed by radioimmunoassay method in the National Center of Science and Nuclear Technical Energy in Maamoura, Morocco. It was observed that the 25-OH-D3 amounts in serum were significantly higher in summer when compared to those measured in winter, while, tissue levels of 25-OH-D3 showed no seasonal variation. (Résumé d'auteur

Finite-element modelling of mechanobiological factors influencing sesamoid tissue morphology in the patellar tendon of an ostrich

The appearance and shape of sesamoid bones within a tendon or ligament wrapping around a joint are understood to be influenced by both genetic and epigenetic factors. Ostriches (Struthio camelus) possess two sesamoid patellae (kneecaps), one of which (the distal patella) is unique to their lineage, making them a good model for investigating sesamoid tissue development and evolution. Here we used finite-element modelling to test the hypothesis that specific mechanical cues in the ostrich patellar tendon favour the formation of multiple patellae. Using three-dimensional models that allow application of loading conditions in which all muscles, or only distal or only proximal muscles to be activated, we found that there were multiple regions within the tendon where transformation from soft tissue to fibrocartilage was favourable and therefore a potential for multiple patellae based solely upon mechanical stimuli. While more studies are needed to better understand universal mechanobiological principles as well as full developmental processes, our findings suggest that a tissue differentiation algorithm using shear strain and compressive strain as inputs may be a roughly effective predictor of the tissue differentiation required for sesamoid development

Musculoskeletal modelling of an ostrich (Struthio camelus) pelvic limb: influence of limb orientation on muscular capacity during locomotion

We developed a three-dimensional, biomechanical computer model of the 36 major pelvic limb muscle groups in an ostrich (Struthio camelus) to investigate muscle function in this, the largest of extant birds and model organism for many studies of locomotor mechanics, body size, anatomy and evolution. Combined with experimental data, we use this model to test two main hypotheses. We first query whether ostriches use limb orientations (joint angles) that optimize the moment-generating capacities of their muscles during walking or running. Next, we test whether ostriches use limb orientations at mid-stance that keep their extensor muscles near maximal, and flexor muscles near minimal, moment arms. Our two hypotheses relate to the control priorities that a large bipedal animal might evolve under biomechanical constraints to achieve more effective static weight support. We find that ostriches do not use limb orientations to optimize the moment-generating capacities or moment arms of their muscles. We infer that dynamic properties of muscles or tendons might be better candidates for locomotor optimization. Regardless, general principles explaining why species choose particular joint orientations during locomotion are lacking, raising the question of whether such general principles exist or if clades evolve different patterns (e.g., weighting of muscle force–length or force–velocity properties in selecting postures). This leaves theoretical studies of muscle moment arms estimated for extinct animals at an impasse until studies of extant taxa answer these questions. Finally, we compare our model’s results against those of two prior studies of ostrich limb muscle moment arms, finding general agreement for many muscles. Some flexor and extensor muscles exhibit self-stabilization patterns (posture-dependent switches between flexor/extensor action) that ostriches may use to coordinate their locomotion. However, some conspicuous areas of disagreement in our results illustrate some cautionary principles. Importantly, tendon-travel empirical measurements of muscle moment arms must be carefully designed to preserve 3D muscle geometry lest their accuracy suffer relative to that of anatomically realistic models. The dearth of accurate experimental measurements of 3D moment arms of muscles in birds leaves uncertainty regarding the relative accuracy of different modelling or experimental datasets such as in ostriches. Our model, however, provides a comprehensive set of 3D estimates of muscle actions in ostriches for the first time, emphasizing that avian limb mechanics are highly three-dimensional and complex, and how no muscles act purely in the sagittal plane. A comparative synthesis of experiments and models such as ours could provide powerful synthesis into how anatomy, mechanics and control interact during locomotion and how these interactions evolve. Such a framework could remove obstacles impeding the analysis of muscle function in extinct taxa