Use of the N-alkanes to Estimate Intake, Apparent Digestibility and Diet Composition in Sheep Grazing on Stipa brevifl ora Desert Steppe

The application of n-alkane as markers to estimate herbage intake, apparent digestibility and species composition of diet consumed by grazing sheep was studied. Six local Mongolian sheep were used to determine dry matter （DM） intake, apparent DM digestibility and species composition of diet during summer, autumn and winter. Animals were orally dosed twice daily with n-alkane gelatin capsules containing 60 mg C32-alkane as an external marker. Diet composition was estimated by comparing the odd-chain n-alkanes pattern profile （C27-C31） of the consumed plant species with the n-alkanes fecal concentrations of grazing animals, using a non-negative least squares algorithm called EATWHAT software package. The alkane pair C32：C33 and C33 alkane were used to estimate DM intake and diet apparent DM digestibility, respectively. The results showed that daily dry matter intake of the sheep were 1.77, 1.61 and 1.18 kg d-1 in summer, autumn and winter, respectively. Apparent DM digestibility, crude protein （CP）, metabolizable energy （ME） and neutral detergent fiber （NDF） intake of diet consumed by sheep decreased significantly （P〈0.01） from summer to winter, with no evident changes in ADF and ADL intake. Diet composition indicated Artemisia frigida Willd was the most dominant diet component, contributed 79.68, 68.12 and 86.26% of sheep＇s diets in summer, autumn and winter, respectively. Cleistogenes songorica Ohwi and Convolvulus arnmannii Desr were the important components of the diet. Although Stipa breviflora Griseb is one of the main plant species in the study area, the sheep rarely choosed it. The study indicated that CP and ME in diet consumed by sheep were deficient in winter. Therefore, appropriate supplementation strategies should be indispensable during this period.

Variations in diet composition of sympatric Trachypithecus francoisi and Macaca assamensis in the limestone habitats of Nonggang, China

Comparative studies of sympatric species are essential for understanding behavioral and ecological adaptation as well as the mechanisms that can reduce resource competition to allow coexistence. Francois＇ langurs （Trachypithecus francoisi） and Assamese macaques （Macaca assamensis） are sympatric primate species found in the limestone seasonal rainforests of Nonggang Nature Reserve, southwestern Guangxi, China. To explore their different adaptation strategies, we collected data on diet using scan sampling at 15-min intervals. Our results revealed that Francois＇ langurs showed a more flexible diet composition than Assamese macaques Francois＇ langurs increased dietary diversity and mature leaf consumption in response to seasonal scarcity of preferred young leaves and fruits, whereas Assamese macaques relied heavily on young bamboo leaves （Indocalamus calcicolus） in most months These variations reflect the differences in digestive physiology, morphology, and the temporal and spatial distribution of food resources.

Diet composition of post-metamorphic bullfrogs(Rana catesbeiana)in the Zhoushan archipelago,Zhejiang Province,China

Bullfrogs(Rana catesbeiana)are listed as one of the 100 worst invasive alien species in the world.They are generalist predators and thus may affect native species through predation.In previous studies,the food contents of bullfrogs were mostly examined at a single site.In the present study,the diet composition of post-metamorphic bullfrogs on eight islands(Daishan,Liuheng,Xiushan,Fodu,Taohua,Xiashi,Cezi,and Putuoshan)in the Zhoushan Archipelago,Zhejiang Province of China,were examined by using the stomach flushing method from June 30 to August 11 in 2005.A total of 391 individual frogs were measured,including 113 adults and 278 juveniles.The analysis of the stomach contents shows that,for adult bullfrogs,the most important prey(by diet volume)overall were Decapoda,Coleoptera,Odonata,Mesogastropoda,Raniformes,and Cypriniformes.For juvenile bullfrogs,these were Decapoda,Coleoptera,Cypriniformes,Odonata,Orthoptera,Hymenoptera,Lepidoptera larvae,Mesogastropoda,and Raniformes.Moreover,the prey size and diet volume increased with the body size of both adult and juvenile bullfrogs.The diet composition of primary preys of bullfrogs was significantly different among the islands.The results indicate that bullfrogs exert different predatory influences on native fauna at different sites and that bullfrogs are generalist predators with extensive ecological impacts on native fauna.

Feeding habits and ontogenetic diet shifts of Bombay duck, Harpadon nehereus

Based on two bottom trawl surveys conducted in autumn 2000 and 2001, a total of 1106 stomach samples of Bombay duck Harpadon nehereus between 23–278 mm fork length were collected and analyzed. The results show that Bombay duck prey items consisted of 11 groups or 32 species, of which Apogon lineatus, Leptochela gracilis, Acetes chinensis, and Euphausia pacifi ca were the dominant prey species. Ontogenetic variations were found in feeding habits and feeding activity of Bombay duck. Feeding activity was highest in fi sh smaller than 50 mm, lowest in fi sh between 50 and 99 mm, and then increased with increasing size thereafter. As Bombay duck size increased, fi sh prey increased in importance, whereas euphausiids and decapods decreased in importance. Different trophic guilds were observed in feeding habits across the examined size range. Bombay duck smaller than 50 mm were zooplanktivores, mainly feeding on zooplankton and fi sh larva; those between 50 and 149 mm were generalist predators, mainly feeding on pelagic shrimps, demersal shrimps and fi shes; and those larger than 150 mm were piscivores, mainly feeding on fi shes.

Optimal diet strategy of a large-bodied psittacine: food resource abundance and nutritional content enable facultative dietary specialization by the Military Macaw

Background:Dietary specialization should arise when there is a relatively high abundance of a particular resource,where animals may select food items to obtain an optimal diet that maximizes energy intake.Large‑bodied psittacines frequently exhibit a narrow dietary niche with specific habitat use,but few studies have determined whether psittacines select food resources,and how this influences habitat use.Methods:We established fruiting phenology transects to evaluate food resource availability for the large‑bodied Military Macaw(Ara militaris)in semi‑deciduous,deciduous,and pine‑oak forest at two sites along the coast of Jalisco,during the dry season when macaws are nesting.We also determined Military Macaw diet by observations of foraging macaws along transect routes,and conducted bromatological analysis of the nutritional content of the most consumed resource.Results:Military Macaws used six plant species as food items during the dry season,and had a narrow dietary niche(Levins’B=0.28),with 56%of foraging macaws consuming the seeds of Hura polyandra.No food resources were recorded in pine‑oak forest during the dry season,with food resources and foraging by macaws concentrated in tropical deciduous and semi‑deciduous forest,where H.polyandra was the most abundant fruiting tree species.When considering the proportional availability of food resources,we determined a broad Hurlbert dietary niche breadth of H=0.67,indicating that Military Macaws consumed food resources according to their availability.Furthermore,the seeds of H.polyandra were an important source of protein,carbohydrates,minerals and moisture,and the hard fruitcasing means that these seeds are exclusively available for macaws.Conclusions:By concentrating their diet on the most abundant resources,Military Macaws may increase foraging efficiency in the dry season.The high nutrient content also means that concentrating the diet on seeds of H.polyandra may be an optimal foraging strategy for Military Macaws to meet their energy requirements during the breeding season.

Food web structure and trophic levels in a saltwater pond sea cucumber and prawn polyculture system

The food sources of aquacultured Apostichopus japonicus and the trophic levels of organisms in a sea cucumber（A. japonicus） and prawn（Penaeus japonica） polyculture system in a saltwater pond in Zhuanghe, Liaoning Province were examined using carbon and nitrogen stable isotopes. Across organisms, δ13C ranged from（–25.47±0.20）‰ to（–16.48±0.17）‰（mean±SD）, and δ15N ranged from（4.23±0.49）‰ to（12.44±0.09）‰. The δ13C and δ15N contents of A. japonicus, P. japonica and Fenneropenaeus chinensis were comparatively higher than those of other organisms. Values of δ13C and δ15N revealed that P. japonica, Hemigrapsus sanguineus and Neomysis japonica comprised the largest component of the diet of A. japonicus. The mean trophic level of the organisms in this saltwater pond polyculture system was（2.75±0.08）. P. japonica, A. japonicus, F. chinensis,Synechogobius hasta and Neomysis japonica were in the 3rd trophic level（2–3）; jellyfish, H. sanguineus and zooplankton were in the 2nd trophic level（1–2）; and Enteromorpha prolifera, benthic microalgae, periphyton and suspended matter primarily consisting of phytoplankton, bacteria and humus were in the primary trophic level（0–1）.

Trophic attributes of the mudskipper, Periophthalmus barbarus (Gobiidae: Oxudercinae) in the mangrove swamps of Imo River Estuary, Nigeria

Aspects of the trophic attributes of the mudskipper, Periophthalmus barbarus occurring in the mangrove swamps of Imo River Estuary, Nigeria, were investigated during a 12 month period (April, 1992\_March, 1993). Feeding intensity increased with size, it was higher in the dry season(November\_April) than in the wet season(May\_October), monthly changes in the indices of feeding intensity were significantly correlated. Major food objects comprised detritus and benthic algae; crustaceans, insects, macrophyte matter and sand grains were minor food objects while fish, molluscs, Chilopoda, nematodes and fungi were unconsciously devoured objects. Diet varied seasonally; algae and sesarmid crabs were generally more in the dry season than during the rains whereas FPOM and fish increased in the wet over dry season. The mudskipper display a high degree of euryphagy and can be considered as a generalist and an omnivore. The lower trophic status of P. barbarus qualifies it as a good aquaculture candidate. Food richness was higher in big sized class(BSC) than small sized class(SSC). Size based and seasonal variations were not apparent in food richness. Diet breadth was higher in the BSC than the SSC, there was dry season increase in diet breadth.

Food Habits and Helminth Parasites of Skittering Frog(Euphlyctis cyanophlyctis)in the Lower Dir,Pakistan

A total of 30 specimens of Skittering frog(Euphlyctis cyanophlyctis),(Anura:Dicroglossidae)were captured from seven selected localities in the Dir Lower,Khyber Pakhtunkhwa province of Pakistan from April to August 2016.They were euthanized with the help of Chloroform(CHcl3)solution.The biometry of each specimen was measured,then dissected to examine for helminth parasites and foodstuff.All helminths were isolated,washed with normal saline at room temperature,and then preserved in 70%GL ethyl alcohol.Later on,the parasites were classified and studied under the electric compound microscope.In a total of 30 specimens,17(56.66%)were found infected with 62 helminths parasites belongs to four different species.Among four species,one was Cestodes Nematotaenia dispar species and remaining three were Nematodes i.e.Cosmocerca species,Cosmocercoides(Raillietnema species)and Strongyloides species.Cosmocerca with a percentage of 56.45%was the most dominant.In the total of 30 specimens’alimentary canal,10 were found empty,containing nothing while in remaining 20 were full of 9 types of food materials which included insects i.e.Ants,Beetles,Wasps,Spiders,Mosquito larvae and cockroaches,and non-living things like stone pebbles and mollusks shells.Among the serial,flies and snails were in the lowest prevalence and ants were recorded the most important component of the frog diet.Among the insects,ants have occurred in higher prevalence 44.50%and flies 1.15%with the lowest prevalence.The results emphasize the significance of further expected studies in the Dir Lower to get a good understanding of the helminth parasites with the ecological relations of their hosts.

Seasonal resource use and niche breadth in an assemblage of coexisting grazers in a fenced Park

Many small Parks inKenyaare being fenced to control human-wildlife conflict. Some of these Parks have a diversity of large herbivores which might increase in density in the wake of fencing and subsequent compression of their home ranges due to closure of their migratory routes. It is important to understand the consequences of such an increase on the structuring of insularised herbivore assemblages in such Parks. We studied seasonal resource segregation and niche breadth variation as mechanisms of coexistence in a high density grazer assemblage inLakeNakuruNational Parkwhich is small and completely fenced. Diet composition and habitat use were considered as variables of resource use. We predicted that overlap in resource use and niche breadth would be the smallest among grazers with similar body weights in the dry season which is the most resource limiting for grazers in East Africa. Our results were contrary to the predictions because of lack of seasonal differentiation in the overlap of diet composition and habitat use, and in niche breadth. Overlaps in resource use were consistently high during both the wet and dry seasons, and niche breadth contraction during the dry season was not possible probably because of lack of species-specific niches during the dry season. Our results suggest that there might be competitive interactions in this grazer assemblage which is an important parameter to consider in the management of the Park.

Positive effect of spring advance on the diet quality of an alpine herbivore

Changes in vegetation phenology related to global warming are having alarming effects on the life history traits of many herbivore species.Such changes are particularly critical in alpine ecosystems,where strong climate limitations on plant growth make seasonal synchronization imperative for the growth,reproduction and survival of herbivores.However,despite the pivotal role of resource-use strategies on the performances of such species,few studies have explicitly assessed the mechanistic impact of climate change on their diets.We aimed to fill this gap by studying the effect of spring onset on the dietary composition and quality of a medium-size alpine herbivore while considering density-dependent processes and age-and sex-specific differences in foraging behavior.Using an exceptional,long-term(24 years)direct individual-based dietary monitoring of a Pyrenean chamois population(Rupicapra pyrenaica pyrenaica),we showed that ongoing earlier onsets of spring are leading to an earlier access to high-quality forage and therefore a higher diet quality at a fixed date,without apparent changes in diet composition.We also showed that at high densities,intraspecific competition reduced diet quality by driving animals to feed more on woody plants and less on nutritious forbs and graminoids.By assessing the mechanistic effects of global warming on the dietary patterns of species at the center of trophic networks,this study is an essential step for predictive models aiming at understanding the ongoing ecosystem consequences of the global climatic crisis.

Chowing down:diet considerations in rodent models of metabolic disease

Diet plays a substantial role in the etiology, progression, and treatment of chronic disease and is best considered as a multifacetedset of modifiable input variables with pleiotropic effects on a variety of biological pathways spanning multiple organ systems. Thisbrief review discusses key issues related to the design and conduct of diet interventions in rodent models of metabolic disease andtheir implications for interpreting experiments. We also make specific recommendations to improve rodent diet studies to help betterunderstand the role of diet on metabolic physiology and thereby improve our understanding of metabolic disease.

Estimation of herbage intake and digestibility of grazing sheep in Zhenglan Banner of Inner Mongolia by using n-alkanes

To reveal the seasonal dynamics of herbage intake, diet composition and digestibility and clarify the relationship of those with herbage nutrient and botanical composition of grazing sheep in Zhenglan Banner of Inner Mongolia, the n-alkane technique was used to test in sheep grazed during June, August and December. The results showed that the sheep mainly ate Fringed sagebrush, Stipa krylovii and Carex in proportions of 33.5,17.9 and 21.2%, respectively, in spring. In summer, the sheep consumed cleistogenes,Potentilla tanacetifolia, Thyme, etc; the intake of Fringed sagebrush, Carex and Stipa declined. In winter,Fringed sagebrush accounted for 50.1% of herbage intake, and the intakes of Cleistogenes and Stipa krylovii increased to 15.3 and 18.4%, respectively. Herbage intake by the sheep in spring was 1.8 kg DM/d, and digestibility was 71.4%. Herbage intake and digestibility decreased slightly to 1.7 kg DM/d and 68.4%during the summer, respectively and decreased significantly to 1.2 kg DM/d and 36.4% in winter. There were significant correlations between diet composition and CP content in winter, diet composition and botanical composition in summer. A highly positive correlation between herbage intake and digestibility was observed in grazing sheep.

Bats as the main prey of wintering long-eared owl(Asio otus)in Beijing:Integrating biodiversity protection and urban management

The loss of biodiversity from urbanized areas is a major environmental problem challenging policy-makers throughout the world.Solutions to this problem are urgently required in China.We carried out a case study of wintering long-eared owls(Asio otus)and their main prey to illustrate the negative effects of urbanization combined with ineffective conservation of biodiversity in Beijing.Field monitoring of owl numbers at two roosting sites from 2004 to 2012 showed that the owl population had fallen rapidly in metropolitan Beijing.Analysis of pellet contents identified only seven individuals of two species of shrew.The majority of mammalian prey comprised four bat and seven rodent species,making up 29.3%and 29.5%of the prey items,respectively.Prey composition varied significantly among years at the two sample sites.At the urban site the consumption of bats and rodents declined gradually over time,while predation on birds increased.In contrast,at the suburban site the prey composition showed an overall decrease in the number of bats,a sharp increase and a subsequent decrease in bird prey,and the number of rodent prey fell to a low point.Rapid development of real estate and inadequate greenfield management in city parks resulted in negative effects on the bird and small mammal habitat of urban areas in Beijing.We suggest that measures to conserve biodiversity should be integrated into future urban planning to maintain China’s rich biodiversity while also achieving sustainable economic development.