Degradability of amino acids in selected legume forages using the in situ nylon-bag technique     

Simbarashe Katsande  Joseph J Baloyi  Florence V Nherera-Chokuda  Nobbert T Ngongoni  Jacob Gusha  Gift Matope 《African Journal of Range and Forage Science》2018,35(2):131-135

This study was conducted to determine the amino acid profiles and rumen degradability of amino acids of three cultivated forage legumes – velvet bean (Mucuna pruriens), cowpea (Vigna unguiculata) and silverleaf desmodium (Desmodium uncinatum) – using the in situ nylon-bag technique. Two Friesian cows fitted with 10-cm-diameter rumen cannulae on a complete dairy feed ration (19% crude-protein dairy meal and maize silage) were used. Silverleaf desmodium had significantly (p < 0.05) higher concentration of amino acids compared with cowpea and velvet bean. Aspartic acid showed the highest (p < 0.05) concentration in all legumes and cysteine showed the lowest concentration. Legume forage of cowpea showed the highest (p < 0.05) level of degradability of amino acid followed by silverleaf desmodium and then velvet bean. Readily and slowly degradable components in all amino acids were highest (p < 0.05) in cowpea followed by silverleaf desmodium and then velvet bean. Moreover, silverleaf and cowpea showed higher (p < 0.05) levels of effective degradability of amino acids (at outflow rates p = 0.02, 0.04 and 0.06 h^?1) than velvet bean. Total amino acid disappearance was the least in velvet bean, which suggests that it can be used to supply bypass protein to the duodenum of the ruminant animal.  相似文献   

Vegetation Response to Juniper Reduction and Grazing Exclusion in Sagebrush-Steppe Habitat in Eastern Oregon     

Jacob W. Dittel  Dana Sanchez  Lisa M. Ellsworth  Connor N. Morozumi  Ricardo Mata-Gonzalez 《Strength and Conditioning Journal》2018,71(2):213-219

Western juniper expansion is one of the largest threats to conserving sagebrush steppe ecosystems in the northwestern United States. Juniper expansion has degraded the sagebrush steppe by altering fire regimes and outcompeting shrubs and herbaceous vegetation for limited resources. We characterized the effect of juniper removal in a severely degraded sagebrush steppe habitat for 3 yr following juniper cutting. In addition, we measured the effect of low-intensity seasonal grazing on plant community recovery through cattle exclusion treatments. We monitored plant community composition (exotic annual grasses, preferred grasses, preferred forbs, and shrubs); fuel loads; and juniper recruitment in a factorial design of juniper removal and grazing exclusion. We found that although there were significant differences between cut and uncut juniper treatments, there were no consistent trends across all 3 yr. Our results suggest that other factors, such as timing of precipitation, may also have strong short-term effects on plant community composition. We detected no significant grazing effects during the study period, suggesting the current grazing regime is appropriate for the area. The cutting of juniper increased total fuel loads and herbaceous fuel loads. Compared with open interspace, a twofold increase in juniper seedlings and saplings was detected beneath juniper piles, which will act as sources for future juniper encroachment.  相似文献   

Tracking the evolution of a hydrothermal event plume with a RAFOS neutrally buoyant drifter     

JE Lupton  ET Baker  N Garfield  GJ Massoth  RA Feely  JP Cowen  RR Greene  TA Rago 《Science (New York, N.Y.)》1998,280(5366):1052-1055

The migration and evolution of a deep ocean hydrothermal event plume were tracked with a neutrally buoyant RAFOS float. The float remained entrained in the plume for 60 days, and the plume vorticity was calculated directly from the anticyclonic motion of the float. Concentrations of suspended particles, particulate iron, and dissolved manganese in the plume did not decay significantly during the 60 days, which indicates that event plumes would be easily detectable a year after formation.  相似文献   

Paleolithic population growth pulses evidenced by small animal exploitation   总被引：1，自引：0，他引：1  

MC Stiner  ND Munro  TA Surovell  E Tchernov  O Bar-Yosef 《Science (New York, N.Y.)》1999,283(5399):190-194

Variations in small game hunting along the northern and eastern rims of the Mediterranean Sea and results from predator-prey simulation modeling indicate that human population densities increased abruptly during the late Middle Paleolithic and again during the Upper and Epi-Paleolithic periods. The demographic pulses are evidenced by increasing reliance on agile, fast-reproducing partridges, hares, and rabbits at the expense of slow-reproducing but easily caught tortoises and marine shellfish and, concurrently, climate-independent size diminution in tortoises and shellfish. The results indicate that human populations of the early Middle Paleolithic were exceptionally small and highly dispersed.  相似文献   

壳聚糖对动物脂肪代谢及生长性能的影响   总被引：7，自引：2，他引：5  

丁晓岚  闫素梅  塔娜 《饲料工业》2005,26(12):8-9

壳聚糖(chifosan),是甲壳素的衍生物．又名可溶性甲壳素、脱乙酰甲壳素、甲壳胺、几丁聚糖．是通过甲壳素一定程度的脱乙酰而得到．通常将脱乙酰度55％以上的甲壳素称作壳聚糖,化学名称是(1．4)-2-氨基-2-脱氧-β-D-葡聚糖。在众多的天然多糖中,甲壳素及其主要衍生物壳聚糖是唯一的碱性多糖．具有生物相容性、可食用性、可抗菌性、  相似文献   

Effects of acute environmental and handling exposure on physiology and fillet quality of market‐sized Channel Catfish     

Shay Allred  Wenjie Shao  Jacob H. Jones  M. Wes Schilling  Beth H. Baker  Peter J. Allen 《Aquaculture Research》2020,51(5):1854-1866

Catfish Ictalurus spp. are subjected to stressful conditions during harvest, which may be linked to fillet coloration and quality. Poor water quality in ponds, socks or hauling tanks, as well as handling stress, have been suggested to cause red fillets in catfish; however, chronic exposure has not resulted in red fillets. Short‐term occurrences of extreme poor water quality, particularly low dissolved oxygen, high carbon dioxide and high temperature, may occur in ponds or during harvest. Therefore, market‐sized Channel Catfish Ictalurus punctatus were acutely exposed (12 hr) to one of the three water quality treatments while confined during a simulated socking procedure and evaluated for stress responses by means of change in blood parameters and fillet quality. In fish subjected to the extreme treatment, hematocrit, plasma cortisol, glucose and lactate levels increased, with 22% mortality, indicating highly stressful conditions. In fish subjected to moderate and typical (control) treatments, cortisol increased but a lack of change or decrease in glucose and lactate indicated minimal anaerobic metabolism. Only one red fillet was produced by the extreme treatment and two by the typical treatment; therefore, the results suggest red fillets are not a product of poor water quality compounded by handling during harvest.  相似文献   

A comparative molecular field analysis study of obtusifoliol 14α-methyl demethylase inhibitors     

Tom M Bargar  Jacob Secor  Lowell D Markley  Brian A Shaw  Jon A Erickson 《Pest management science》1999,55(11):1059-1069

This report describes the development of a Comparative Molecular Field Analysis (CoMFA) model from a set of obtusifoliol 14α-methyl demethylase (DM) inhibitors to aid in the design of herbicides targeting sterol biosynthesis. CoMFA is a three-dimensional (3-D) quantitative structure–activity relationship (QSAR) method that is useful in the probing of receptor binding sites when experimental structure data are unavailable. Conformational analysis and SAR of some rigid and active analogs were used to build the initial model using the active analog hypothesis. The model was subsequently used to design compounds that retain the active site shape requirements, but incorporate physical properties that favor soil-applied herbicidal action. In addition, a second-generation CoMFA model incorporating the newly designed inhibitors was developed and represents the current understanding of the DM binding site. This model was derived from a pharmacophore developed from two methods, the active analog approach as well as from the Catalyst program. The fact that two independent methods produced a similar pharmacophore strengthens the validity of the model. © 1999 Society of Chemical Industry  相似文献   

The role of shore crabs and mussel density in mussel losses at a commercial intertidal mussel plot after seeding     

Jacob J. Capelle  Gerard Scheiberlich  Jeroen W. M. Wijsman  Aad C. Smaal 《Aquaculture International》2016,24(5):1459-1472

Mussel losses peak after relaying seed on culture plots. The present paper is an attempt to examine the role of shore crab predation and initial mussel density on mussel losses in mussel bottom culture using an intertidal culture plot as a case study. Because of their small size and loose attachment, mussels are particularly vulnerable to predation at this stage, as well as to handling stress and intraspecific competition. In the experimental field plots (1 × 1 m) in the intertidal Oosterschelde, three different densities (1, 5 and 10 kg m^?2) of mussel seed are laid, with half of the experimental plots protected from predation by means of exclosures. Duration of the experiment was 5 weeks (August–September 2012) post-seeding. Protection was the major factor accounting for biomass production, followed by mussel density. Loss rates increased with mussel density, both in the exclosures and in the exposed plots. Losses in the exclosures with the lowest density were still 45 %. There are indications that handling stress prior to the start of the experiment played a major role in these losses. At the higher densities in the exclosures, losses increased to 72.1 % and were not significantly different between 5 and 10 kg m^?2. About one-third of the total loss (32.6 %) was attributed to shore crab predation. The number of shore crabs observed on the plots did not differ between treatments. Byssal thread development during the experimental period was followed and was found to be a slow process that was insufficient to protect mussels from crab predation at the sheltered experimental location.  相似文献   

Assessing the prospects of Streptomyces sp. RP1A-12 in managing groundnut stem rot disease caused by Sclerotium rolfsii Sacc     

Simi Jacob  Ramgopal Rao Sajjalaguddam  K. Vijay Krishna Kumar  Rajeev Varshney  Hari Kishan Sudini 《Journal of General Plant Pathology》2016,82(2):96-104

  相似文献   

Ecophysiology of iron homeostasis in plants     

Cesar Abel Krohling  Frederico Jacob Eutrópio  Amanda Azevedo Bertolazi  Leonardo Barros Dobbss  Eliemar Campostrini  Teresa Dias 《Soil Science and Plant Nutrition》2016,62(1):39-47

In nature, iron (Fe) occurs in abundance and ranks fourth among all elements on Earth’s surface. Still, its availability to plants is reduced, once this element is in the form of hydrated oxides, which can limit plant productivity and biomass production. On the other hand, in high concentrations, this essential micronutrient for the plants can become a toxic agent, increasing the environmental contamination. Fe is necessary for the maintenance of essential processes like respiration and photosynthesis, participating in the electron transport chain and in the conversion between Fe²⁺ and Fe³⁺, being a key element for carbon dioxide (CO₂) fixation and, therefore, important for crop production of cultivated or natural species. The balance of Fe should be strictly controlled, because both its deficiency and its toxicity affect the physiological process of plants. In aerated soils Fe is present in the form of Fe³⁺, which is the oxidized form and is less available to plants, so these organisms have developed different strategies for absorption, transport and storage of Fe. Deficiency and excess of Fe correlate with local soil conditions and with the care adopted in plant nutrition during the phenological phases and/or in the course of its cultivation. In situations of excessive accumulation of Fe in tissues, an enhancement of hydroxyl radical generation (OH^?) occurs by Fenton reaction. Here, we review the nutritional, genetic and ecophysiological aspects of uptake, translocation and accumulation of Fe ions in plants growing under conditions of deficiency or toxicity of this metal.  相似文献