新银合欢种子的萌发检验

通过用4个不同恒温、1个变温及用80 ℃热水、98%的浓硫酸不同时间分别浸种对新银合欢Leucaena leucocephala种子进行发芽试验,研究不同处理水平和不同处理组合对新银合欢种子萌发的影响.结果表明:在不同处理水平下,新银合欢种子发芽率、发芽势的最佳温度分别为18 ℃16 h/28 ℃8h 变温和20 ℃恒温,发芽率、发芽势的最佳热、酸蚀处理分别为酸蚀20和45 min;在不同处理组合下,新银合欢种子发芽率、发芽势最佳处理组合均是18 ℃16h /28 ℃8h 变温与98%浓硫酸浸种45 min的组合.     

银合欢硬实种子处理方法研究

采用7种不同方法对银合欢Leucaena leucocephala种子进行处理,结果表明,用98%的浓硫酸对银合欢种子进行处理5 min效果最好,发芽率达86%;其次是水温80℃浸种10 min,发芽率达74%;80℃高温干燥10 min和机械摩擦种皮效果比较差,发芽率仅19.3%和15.3%;酒精、40%的氢氧化钠、不同浓度萘乙酸(NAA)浸种对银合欢的发芽率没有影响,最佳处理的大田试验结果与实验室结果相吻合。     

Anthelmintic effects of Salix babylonica L. and Leucaena leucocephala Lam. extracts in growing lambs

Twenty Katahdin?×?Pelibuey crossbreed male lambs, 3 to 4 months of age and 24?±?0.3 kg of body weight, were used to study the anthelmintic effects of administering extracts of Salix babylonica L. (SB) and Leucaena leucocephala Lam. (LL). Lambs had not been treated with anthelmintics previously and were randomly allocated into four groups of five lambs each in a completely randomized design. Treatments were as follows: control (lambs fed on total mixed ration without extracts), SB (as control plus S. babylonica L. extract at 30 ml/day), LL (as control plus L. leucocephala Lam. extract at 30 ml/day), and SBLL (as control plus 30 ml/day of S. babylonica L. and L. leucocephala Lam. extracts in a 1:1 (v/v) mixture) for 63 days. Extracts were orally administered before the 8:00 a.m. feeding to each lamb. Rectal fecal samples were collected from each lamb at day 22 (P1), day 43 (P2), and day 63 (P3) of the experiment. Adult worm and egg counts were determined in each fecal sample immediately after collection. Plant secondary metabolites of total phenolics, saponins, and the aqueous fraction were 50 % lower in the SB versus LL extracts. Overall, the oral administration of extracts has improved the egg and worm count reductions in lamb feces by 54, 47, and 40 % for LL, SB, and SBLL, respectively, versus the control lambs. Reductions of worm egg counts in lamb feces were higher (P?<?0.05) in P2 and P3 versus P1. Extracts of SB and LL or possibly isolated bioactive compounds could be a promising alternative to conventional anthelmintics to treat gastrointestinal parasites of small ruminants. Such treatments could be used in control strategies against gastrointestinal nematodes in organic and conventional production systems.     

Anthelmintic activity of Jatropha curcas L. seeds on Haemonchus contortus

The aim of this study was to evaluate the anthelmintic activity of hexane (HE), ethyl acetate (EA) and ethanol (EE) extracts obtained from the seeds of Jatropha curcas using the egg hatch inhibition assay (EHA) and the artificial larval exsheathment inhibition assay (LEIA). For the egg hatch assay, HE, EA and EE were used in concentrations of 3.12, 6.25, 12.5, 25 and 50 mg ml(-1), accompanied by a negative control (5% Tween 80) and a positive control (0.025 g ml(-1) thiabendazole). In LEIA, the extracts were tested at a concentration of 1000 μg ml(-1), accompanied by a negative control (PBS). To evaluate the effect of tannins, the extract with the greatest effect was incubated with polyvinyl polypyrrolidone (PVPP). The EE (50 mg ml(-1)) inhibited 99.8% of egg hatching. After the addition of PVPP, the ovicidal effectiveness of EE was reduced to 91.9%. Using the HE and EA, inhibition of egg hatching was 15.3% and 32.2%, respectively. In the LEIA, 18.9% of L3 incubated with EE were exsheathed (p<0.01). The addition of PVPP to EE reversed the inhibitory effect on larval exsheathment. The percentage of exsheathment of L3 incubated with HE (99.6%) and EA (97.8%) did not differ from the control group (p>0.05). The results show that the effects of EE on eggs are not solely due to the tannins. However, these secondary metabolites are implicated in blocking the larval exsheathment.     

Anthelmintic screening of fractions of Elephantorrhiza elephantina root extract against Haemonchus contortus

In the previous work conducted, it was found that the root extract of Elephantorrhiza elephantina (Bruch.) Skeels. exhibited good anthelmintic efficacy against eggs and larvae of Haemonchus contortus. This study was therefore undertaken to screen fractions of the extracts of E. elephantina for their anthelmintic activity against adult H. contortus using a bioactivity-guided assay. The adult worm bioassay was conducted using aqueous, hexane and ethyl acetate fractions of the plant extracts at concentrations of 0.312, 0.625, 1.25, 2.5, 5 and 10 mg/ml in vitro. Albendazole and distilled water were used as positive and negative control, respectively. In vitro treatment of adult worms revealed concentration and time-dependent efficacy of the fractions of E. elephantina. The aqueous and ethyl acetate fractions showed a highly significant (P < 0.05) motility inhibition at concentrations of 2.5 mg/ml and above after 6 h of exposure, while the hexane fraction showed a significant (P < 0.05) motility inhibition at concentrations of 5 mg/ml and above. After 30 h of exposure, all the fractions showed insignificant (P > 0.05) inhibition of motility. The fractions of E. elephantina also showed mortality indexes that were not significantly different to each other, as well as to the commercial drug (albendazole). Overall, the ethyl acetate and the aqueous fractions were found to possess the highest anthelmintic activity. We therefore recommend future studies to further investigate effective dosages of these fractions in vivo, as well as a full investigation into the compounds responsible for the biological activity.     

Anthelmintic efficacy of hydro-methanolic extracts of Larrea tridentata against larvae of Haemonchus contortus

An in vitro study was conducted to determine the anthelminthic activity of hydro-methanolic extracts of Larrea tridentata on sheathed and exsheathed larvae of Haemonchus contortus. Larvae of the parasite were incubated at 20–25 °C in hydro-methanolic extracts at concentrations of 12.5, 25, 50, 100, and 200 mg/mL for 24, 48, or 72 h. Ivermectin and water were the positive and negative controls, respectively. Total phenolic compounds of leaves of L. tridentata were 97.88?±?10.45 mg/g of dry matter. Other compounds detected in this shrub by HPLC-mass spectrometry were sesamin, galocatechin, peonidin 3-O rutinoside, methyl galangin, epigallocatechin 7-O-glucuronide, and epigalocatechin. Mortality rate of sheathed and exsheathed H. contortus was low (16–34%) with doses ≤?100 mg/mL of the extracts. At 200 mg/ml, the hydro-methanolic extracts of L. tridentata killed 32.1 and 68.4% of sheathed and exsheathed larvae, respectively, regardless of incubation time. The effective concentration of the L. tridentata extract for 50% larvae mortality (EC₅₀) after 24 h of incubation was 36 mg/mL (CI?=?6–94). Microscopic observations revealed damage to the cuticle of this parasite exposed to extracts of L. tridentata. These in vitro results provided evidence that L. tridentata extracts possess anti-Haemonchus contortus properties, particularly during the exsheathed stage of this nematode. It would be necessary to assess the safety of this shrub in vivo and also to carry out in vivo efficacy studies.

     

重复吸水-回干处理对银合欢种子发芽率及相关指标的影响

银合欢Leucaena glauca种子在25 ℃恒温下,设置4、8、16、24 h 4个浸泡时间,连续4次进行重复吸水-回干处理.结果表明:不论浸泡时间长短(4～24 h),前3次处理对银合欢种子发芽率均没有显著影响;浸泡次数与种子浸出液的pH值呈负相关关系,与种子的吸水量呈正相关关系;浸泡时间与电导率呈正相关关系;这可为银合欢种子活力测定的非破坏性方法研究提供参考.     

Anthelminthic activity of acetone extract and fractions of Vernonia amygdalina against Haemonchus contortus eggs and larvae

The current control of parasitic nematodes in small ruminants relies on the use of chemical anthelminthics, but the development of resistance and the problem of drug residues require research into alternatives. Acetone extract and solvent–solvent fractions of Vernonia amygdalina Del. (Compositae) were evaluated in vitro for potential anti-parasitic effects against the eggs and larvae of Haemonchus contortus. Significant effects were obtained with the extract and fractions but differences were observed depending on the parasitic stage. The acetone extract and fractions inhibited egg hatching and inhibited larval development and killed larvae of H. contortus in a concentration-dependent manner. Best-fit 50% lethal concentration (LC₅₀) values were 957.0, 76.0, 524.0, 309.0 and 224.0 μg/ml for the acetone extract, and the butanol, hexane, chloroform and 35% water in methanol fractions, respectively, when tested against nematode eggs. Best-fit LC₅₀ values for the larval viability test were 508.2, 485.5, 569.3, 348.9 and 196.6 μg/ml for the acetone extract, and the butanol, hexane, chloroform and 35% water in methanol fractions, respectively. The butanol fraction was most active against nematode eggs while the 35% water in methanol fraction was the most active on nematode larvae, although differences in activity between fractions were not significant (p > 0.05). Overall, these in vitro results suggest that V. amygdalina, traditionally used by small farmers in Western Africa, does possess anti-parasitic properties.     

新银合欢中单宁提取工艺优化研究

对新银合欢（Leucaena leucocephala）中单宁类物质的提取工艺进行优化研究,选择液料比、提取温度、提取时间、提取剂体积分数等因素分别进行单因素和正交试验。结果表明,在液料比40∶1、提取温度50 ℃、提取时间60 min、丙酮体积分数50%的条件下,单宁提取效果最佳,测得新银合欢单宁平均含量为2.54%。     

新银合欢营养成分分析及饲用研究

为促进新银合欢蛋白质资源的饲用开发研究．我们对新银合欢进行了常规营养成分分析和氨基酸测定,并就新银合欢饲喂猪、牛、羊的效果进行了初步探讨,同时对进一步开发利用新银合欢提出了一些建议。     

Anthelmintic activity of essential oil of Ocimum gratissimum Linn. and eugenol against Haemonchus contortus

The ovicidal activity of the essential oil of Ocimum gratissimum Linn. (Labideae) and its main component eugenol was evaluated against Haemonchus contortus, gastrointestinal parasite of small ruminants. The oil and eugenol were diluted in Tween 20 (0.5%) at five different concentrations. In the egg hatch test, H. contortus eggs were obtained from feces of goats experimentally infected. At 0.50% concentration, the essential oil and eugenol showed a maximum eclodibility inhibition. These results suggest a possible utilization of the essential oil of O. gratissimum as an aid to the control of gastrointestinal helmintosis of small ruminants.     

Effect of cutting height and frequency on Leucaena leucocephala forage and wood production

Abstract

Leucaena leucocephala is a fast‐growing tree that can provide both high quality forage and firewood. The objective of this trial was to determine the optimum height and frequency of cutting for both wood and forage production. Cutting heights at 0.3 m, 0.6 m and 1.0 m were superimposed on 3‐month and 6‐month cutting frequencies on mature rows of L. leucocephala for three years. Effects of year or its interaction with the other factors were not significant (P≥0.10). There was an increase (P=0.07) in wood production but not forage production (P≥0.10) with the longer interval. Cutting height had an effect on forage (P<0.001) production, with 5.47 t ha^?1 a^?1 for the 0.3‐m height, 7.62 t ha^?1 a^?1 for the 0.7‐m height, and 8.71 t ha^?1 a^?1 for the 1.0‐m height. Cutting height also had an effect on wood production (P<0.001), with 7.22 t hd^?1 a^?1 for the 0.3‐m height, 9.33 t ha^?1 a^?1 for the 0.7‐mheight, and 11.55 t hd^?1 a^?1 for the 1.0‐m height. In this experiment, the six‐month interval produced more wood than the three‐month interval, but there were no differences in quantity of forage dry matter in L. leucocephala; there were advantages in both wood and forage production with the taller trunk base.     

Multiple Anthelmintic Resistance in Haemonchus Contortus on a Sheep Farm in Kenya

Multiple resistance to albendazole, thiophanate, levamisole and orally administered ivermectin was detected in an isolate of Haemonchus contortus in sheep on a farm where benzimidazole resistance had already been identified. Following a faecal egg count reduction test, this was confirmed by both critical and controlled anthelmintic tests. Different groups of sheep infected naturally or given an experimental infection with the benzimidazole-resistant isolate were treated with the recommended doses of various anthelmintics. Compared to the control group, the percentage reductions in the faecal egg counts of sheep treated with albendazole, thiophanate, levamisole and ivermectin varied between 38.2% and 79.1% and the residual worm counts between 27.3% and 57.5%. The results indicate the presence of multiple anthelmintic resistance in this isolate of H. contortus. Sheep treated with closantel showed 100% reductions in faecal egg and worm counts, indicating that this drug was very effective against the population of H. contortus on the farm.     

Effects of supplementing Leucaena leucocephala and conserved forages from natural pasture on the performance of grazing calves

Twelve white Fulani × N'dama cross-bred calves weighing 83.79?±?1.16 kg were used in an 84-day experiment to investigate the utilization of forage resources from natural grazing land. The experimental diets were sole grazing, grazing + hay, grazing + silage and grazing + Leucaena leucocephala leaves. The calves were divided into four groups of three animals each and were randomly assigned to the four experimental diets. Crude protein (CP) contents of the forages ranged from 59 to 171 g/kg dry matter (DM). Neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents of the forages ranged from 560 to 705 g/kg DM and 363 to 440 g/kg DM, respectively. Significantly (P?<?0.05) higher values in mineral contents (Ca, K, P and Mg) were recorded for L. leucocephala leaves compared to other forage resources. Variations (P?<?0.05) were observed in the average daily gain. Animals on grazing + L. leucocephala leaves diet had the highest (113 g/day) average daily gain, while those on sole grazing showed the least value (26.2 g/day). Packed cell volume (PCV), total serum protein, urea and calcium concentration showed significant differences (P?<?0.05). Effective utilization of forage resources from the natural pasture by the calves was attained on supplementation with conserved forages and L. leucocephala leaves without any deleterious effects on the haematological and serum parameters.     

Seasonal variation in forage quality and mimosine contents of two varieties of Leucaena leucocephala

Seasonal variation in forage quality and mimosine contents of two varieties (cultivars Cunningham and Spectra) of Leucaena leucocepha/a were evaluated. Cultivar (cv.) Cunningham was available throughout summer, autumn, winter and spring seasons while cv. Spectra was available during summer, winter and spring seasons. Differences in crude protein (CP) and mimosine contents of young Cunningham and Spectra leaves were not significant. Also, difference in mimosine contents of mature leaves of both cultivars were not significantly different. But mean CP content of mature Spectra leaves was significantly higher (24.9 vs 18.7%, p = 0.023) than that of leaves of mature Cunningham. Mean P content of young Spectra leaves was significantly higher (1.6 vs 2.10gkg^?1, p = 0.046) than that of young Cunningham leaves but mean Cu content of young Cunningham leaves was higher (10.5 vs 9.0mgkg^?1, p = 0.06) than that of young Spectra leaves. Mature leaves of cv. Spectra also had higher P content (2.3 vs 1.6gkg^?1, p = 0.06), but lower Ca (20.8 vs 30.5gkg^?1, p = 0.06) and Mg (5.6 vs 7.6gkg^?1, p = 0.06) contents than those of mature Cunningham leaves, Apart from CP, fat and mimosine, other analysed constituents increased with plant maturity.     

Effect of dietary inclusion of Leucaena leucocephala or Moringa oleifera leaf meal on performance of growing rabbits

This experiment was carried out to evaluate the effect of including either Leucaena leucocephala (LLM) or Moringa oleifera leaf meal (MOLM) as tropical feed resources at two levels (30 or 40 %) on growth performance, carcass traits, and economical efficiency of growing rabbits. A total of 60 California growing rabbits were randomly distributed into five experimental groups, each consisting of 12 rabbits and were allocated individually; the groups were control, 30 % LLM, 40 % LLM, 30 % MOLM, and 40 % MOLM. The experimental period lasted from 6 to 12 weeks of age. The results showed that rabbits fed control and 30 % MOLM diets had significantly the highest final body weight and daily weight gain being 2,040 and 2,000 g and 31.6 and 30.6 g/day, respectively. Similarly, the best feed conversion ratio was associated with 30 % MOLM and control groups (3.2 and 3.4), while the worst value was for 40 % LLM group (5.2). MOLM treatments recorded significantly the highest dressing percentage along with control group. The inclusion of MOLM by 30 and 40 % improved the economical efficiency (2 and 1.5) in comparison with the control group (1.1). The results suggest that MOLM can be included in growing rabbit diets up to 40 % without any adverse effect on growth performance or carcass traits with higher economical efficiency of growing rabbits.     

Motility response of levamisole/benzimidazole-resistant Haemonchus contortus larvae

Electronic measurements of the motility of third stage larvae of a susceptible and a levamisole/benzimidazole-resistant strain of Haemonchus contortus were made after incubation in solutions of anthelmintics for 24 h. Results confirmed the resistance to benzimidazoles, but failed to show differences in response to levamisole. Visual observations of paralysis of first and third stage larvae in solutions of levamisole also failed to show significant differences between the two strains. The tests as conducted failed to demonstrate levamisole resistance, suggesting that nematode strains may vary in their mechanisms of resistance to levamisole.