Tropical floodplain agroforestry systems in mid-Orinoco River basin,Venezuela     

E. Barrios  R. Herrera  J. L. Valles 《Agroforestry Systems》1994,28(2):143-157

Agricultural studies in seasonally flooded areas in the tropics have been limited. Orinoco alluvial soils are more fertile than adjacent non-flooded soils, and have been considered as potential areas for further agricultural development. Traditional agroforestry practices offer some possibilities to overcome the most limiting factors of floodplain cultivation. Indigenous knowledge of these traditional agroforestry practices was assessed and some indicators of the system's nitrogen and biomass dynamics were monitored. Nitrogen inputs by sediment and plant residues were 1668 and 47 kg ha^–1, respectively. Traditional selection of sediment by tree-and-grass barriers and litter management strategies increase nutrient-use efficiency in floodplain agroecosystems.

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Resumen Estudios agrícolas en areas tropicales sujetas a inundación estacional han sido limitados. Los suelos aluviales o vegas del Orinoco son más fértiles que suelos cercanos no sujetos a inundación y por lo tanto han sido considerados como areas potenciales para desarrollos agrícolas. Prácticas tradicionales de agroforestería constituyen una alternativa en el control de importantes factores limitantes en la agricultura de vegas. El conocimiento técnico autóctono asociado con prácticas agroforestales tradicionales de vegas fue evaluado y algunos indicadores de la dinámica de nitrógeno y biomas adel sistema fueron monitoreados. La contribución de nitrógeno por sedimentos y hojarasca fue de 1668 and 47 kg ha^–1 respectivamente. La selección del tipo de sedimento a depositarse en la parcela agrícola, por medio de barreras de vegetación, y el manejo adecuado de resíduos orgánicos constituyen estrategias tradicionales que aumentan la eficiencia de uso de nutrientes en sistemas agrícolas de vegas.

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Detection of bovine torovirus in neonatal calf diarrhoea in Lower Austria and Styria (Austria)     

Haschek B  Klein D  Benetka V  Herrera C  Sommerfeld-Stur I  Vilcek S  Moestl K  Baumgartner W 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2006,53(4):160-165

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全肠外营养脂肪乳剂脂肪酸形态对仔猪不同组织中脂肪酸组成的影响     

叶帅 《饲料与畜牧》2009,(4):47-51

目前,人类婴儿低初生重的总肠外营养（TPN）研究表明脂肪乳剂对于新生儿的营养是合适的,但不是最佳的选择。人类和猪的脂肪酸代谢非常相似,目前的研究主要集中在脂肪乳剂如何在TPN的临床作用。不同组成脂肪酸对新生仔猪进行7d处理,对于靠母乳替代物的仔猪而言,对组织脂肪酸的组成存在影响。在脂肪乳中,不同比例脂肪酸或母乳替代物对应的血浆,骨骼肌、皮下脂肪、肝脏、心脏,胰腺,胃及小肠的总血脂或脑磷脂呈正态的线性关系,而后者相关性最低。除大脑外,组织中的油酸或α-亚麻酸的比例与对应的脂肪乳或者母乳替代物相关,而亚麻酸的比例与研完的组织密切相关。除脑磷脂外,omegaven组中仔猪组织的二十碳五烯酸和二十二碳六烯酸含量更高。结论除大脑外,血浆脂肪酸组成以及仔猪不同组织受全肠外营养乳剂中不饱和脂肪酸形态的影响极大。然而,脑磷脂脂肪酸的组成受日粮组成的影响要小,表明在生长的关键阶段有效的代谢是确保脂肪酸组成的关键。  相似文献   

Root growth of maize in an Italian ryegrass living mulch studied with a non-destructive method     

Marc Faget  Markus LiedgensBoy Feil  Peter StampJuan M. Herrera 《European Journal of Agronomy》2012,36(1):1-8

The use of living mulch (LM) systems for maize (Zea mays L.) cultivation may reduce soil erosion and nitrate leaching. However, the yield of maize cultivated in LM is lower than in conventional farming systems. This decrease has often been attributed to belowground competition, but the lack of a suitable method to demonstrate such competition has prevented further investigation. A recently developed method allows for the direct and non-destructive observation of root growth in LM. Maize expressing a green fluorescence protein was grown in monoculture or together with Italian ryegrass (Lolium multiflorum Lam.). Root growth was screened in minirhizotrons from the time of sowing to the anthesis of the maize.Compared with the maize cultivated without Italian ryegrass, the cultivation in the LM significantly (p < 0.05) reduced the shoot dry matter (56%), leaf area (39%) and mean root density (41%) of the maize at anthesis. An analysis of variance showed that the reduction due to the living Italian ryegrass in the root density of the maize was not significantly different from the reduction in leaf area. Similarly, the reduction in the root density and shoot dry matter of the maize were not significantly different. The roots of the LM maize grew in the soil where the LM was removed but also where the LM continued growing. This study constitutes the first direct quantification of root growth and distribution in a LM system.  相似文献   

Osmoregulation in fish sperm     

Herrera  Fabio  Bondarenko  Olga  Boryshpolets  Sergii 《Fish physiology and biochemistry》2021,47(3):785-795

Fish Physiology and Biochemistry - In most fish exhibiting external fertilization, spermatozoa become motile after release into water, triggered by differences between intracellular and...  相似文献   

Effects of exogenous fibrolytic enzymes on ruminal digestibility in steers fed high fiber rations     

G. lvarez  J.M. Pinos-Rodríguez  J.G. Herrera  J.C. García  S.S. Gonzalez  R. Brcena 《Livestock Science》2009,121(2-3):150-154

The effects of two exogenous fibrolytic enzyme products on ruminal disappearance and fermentation of oat straw-wheat middlings based diets were evaluated. Six steers (322 ± 34.4 kg body weight) fitted with ruminal cannulas were used in a 3 × 3 Latin square replicated. The treatments consisted of: 1) control, 2) Fibrozyme (2 g/kg dry matter), and 3) Promote (3 ml/kg dry matter). Both, Fibrozyme (Alltech Inc.) and Promote NET (Cargill Corp.) were sprayed as liquid onto diets and feeds 24 h before feeding. Samples of diets were ruminally incubated from 0 to 72 h. Enzymes did not change dry matter intake, average daily gain and feed conversion. Fibrozyme increased crude protein (CP) disappearance rate of diet, while Promote increased CP total disappearance. In diets, enzymes did not affect ruminal neutral detergent fiber (NDF) and acid detergent fiber (ADF) fractions. Fibrozyme and Promote did increase CP total disappearance, ADF potential disappearance and ADF disappearance rate of wheat middlings, as well as dry matter (DM) and CP total disappearance, NDF disappearance rate, ADF potential disappearance and ADF disappearance rate of oat straw. Ruminal pH values were higher with enzymes, as compared to control. Total volatile fatty acids concentration and molar proportion of acetate and butyrate were not affected by both enzymes, but molar proportion of propionate was lower and acetate:propionate ratio higher with Promote than control. Fibrozyme and Promote did increase DM and CP soluble fractions of diets, as well as, ADF potential disappearance of wheat middling and oat straw.  相似文献   

Constraints on dairy cattle productivity at the smallholder level in the Philippines     

Alejandrino AL  Asaad CO  Malabayabas B  De Vera AC  Herrera MS  Deocaris CC  Ignacio LM  Palo LP 《Preventive veterinary medicine》1999,38(2-3):167-178

Survey data on dairy cattle production were gathered in two sites [Site I (three-year survey) and Site II (two-year survey)] in Southern Luzon, Philippines. Crossbred (Holstein-Friesian x Sahiwal) dairy cows (n = 122) managed by smallholder farmers belonging to five primary cooperatives under the federation of dairy farmers, were monitored monthly for milk production, feed intake and availability, and reproduction and health status. The purpose of the survey was to identify constraints to productivity. The reproductive status of the cows was monitored by measuring milk and plasma progesterone concentrations by radioimmunoassay and rectal palpation of the ovaries. Plasma concentrations of selected metabolites [beta-hydroxybutyrate (BHB), inorganic phosphorus, albumin, globulin, urea] were also measured at one month before calving and at one month and 2-3 months postpartum, to determine if these could serve as biochemical indicators of nutritional stress. A long calving interval (CI = > 400 days) was identified as the major constraint to productivity of dairy cattle on smallholder farms. The three main problems related to this reproductive constraint were: (1) poor breeding management, in particular lack of accurate estrus detection; (2) repeat breeding, i.e. three or more services were required before conception; and (3) poor ovarian function, shown by some cows with lose progesterone levels. An important cause of these problems was undernutrition, particularly at critical periods of the cow's reproductive life, reflected in the slow recovery from loss in body weight and condition score during the early postpartum period and the increased plasma BHB values at peripartum period in some cows, indicative of negative energy balance, and the flat lactation profile. These findings are useful and relevant as a database in the development of an appropriate management scheme aimed toward improving dairy cattle production and productivity at smallholder level. It highlights the importance of estrus detection, good breeding management and the use of a practical strategic nutritional supplementation, particularly during stressful periods in the cows's reproductive life.  相似文献   

Effect of larval stocking density on growth,survival and whole body cortisol of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819) larvae reared under laboratory conditions          下载免费PDF全文

Luis Lagos  Marcelino Herrera  Clara Sánchez‐Lazo  Inés Martínez‐Pita 《Aquaculture Research》2015,46(7):1648-1656

Interest of mussel hatchery development has increased during the last years as natural seed collection does not always satisfy the demand of producers. Success on larval bivalve culture depends on several factors such as diet, temperature or stocking density. In this study, the effect of larval density in mussel culture success has been assessed testing three larval densities: high (50 larvae mL^?1), medium (25 larvae mL^?1) and low (5 larvae mL^?1). Results showed higher growth and survival at low density but the amount of postlarvae was low. The highest number of settled larvae was observed at high density but mortality was also high and a delay on the larval development was detected producing a prolongation on the culture length. However, medium density resulted in a good survival and growth and also in a considerable amount of postlarvae, as this density could be adequate for massive mussel seed production. Cortisol content on the larvae and postlarvae was also analysed and significant differences were obtained among groups probably due to the stress associated to settlement and metamorphosis.  相似文献   

First detection of spring viraemia of carp virus in common carp (Cyprinus carpio L.) affected by a septicaemic disease in Mexico     

Cesar Ortega  Leticia Caas‐Lopez  Rute Irgang  Raúl Fajardo  Matías Poblete‐Morales  Benjamin Valladares-Carranza  Diana Tapia‐Cammas  Ruben Avendao‐Herrera 《Journal of fish diseases》2019,42(5):667-675

Spring viraemia of carp (SVC) is an infectious disease responsible for severe economic losses for various cyprinid species, particularly common carp (Cyprinus carpio carpio). The causative agent is the SVC virus (SVCV), a member of the Sprivivirus genus, Rhabdoviridae family, and a List 1 pathogen notifiable by the World Organization for Animal Health. This study describes the diagnosis of an SVCV pathogen isolated in October 2015 from wild common carp inhabiting a natural lagoon in central Mexico. While neither an epidemic nor fish mortalities were reported, the collected killed specimens exhibited clinical signs of disease (e.g., exopthalmia, moderate abdominal distension and haemorrhaging, as well as internal haemorrhages and adhesions). Histological results of injuries were consistent with the pathology caused by SVCV. This finding was supported by the isolation of a virus in EPC and BF‐2 cells and subsequent RT‐PCR confirmation of SVCV. The phylogenetic analyses of partial SVCV glycoprotein gene sequences classified the isolates into the Ia genogroup. These findings make this the first report of SVCV detection in Mexico, extending the southern geographical range of SVCV within North America. However, since this pathogen was detected in fish inhabiting a natural body of water without tributaries or effluents, it is difficult to estimate the risk of SVCV for other wild/feral cohabitating cyprinid species in the lagoon. The status of this virus is also unknown for other bodies of water within this region.  相似文献   

Osmoregulatory changes in wedge sole (Dicologoglossa cuneata Moreau, 1881) after acclimation to different environmental salinities     

Marcelino Herrera  Luis Vargas-Chacoff  Ismael Hachero  Ignacio Ruíz-Jarabo  Ana Rodiles  José I Navas  & Juan M Mancera 《Aquaculture Research》2009,40(7):762-771

The osmoregulatory responses of 20 days of acclimation to environmental salinities of 5‰, 15‰, 25‰, 35‰ and 55‰ were assessed in juveniles of wedge sole ( Dicologoglossa cuneata Moreau, 1881). This sole shows a good capacity to adapt to this range of environmental salinities. A direct linear relationship between environmental salinity and plasma osmolality was observed, with a calculated isosmotic point of 10.4‰ (284 mOsm kg⁻¹). Na⁺, K⁺-ATPase activity in the gills followed a 'U-shaped' relationship with environmental salinity, and a direct linear relationship in kidney tissue. Plasma cortisol levels were elevated in fish held in extreme salinities, and glucose levels were higher only in the group maintained at the highest environmental salinity. In the liver, a decrease in glycogen, lactate and amino acid contents was observed in specimens acclimated to extreme salinities (5‰ and 55‰), suggesting mobilization of liver metabolites. Metabolite levels in white muscle showed a pattern similar to the liver, with lower values in specimens acclimated to extreme salinities. We conclude that wedge sole is strongly euryhaline, but acclimation to extreme salinities comes with an energetic cost.  相似文献