Laboratory and field observations on anti-tick properties of the plant Gynandropsis gynandra (L.) Brig.

A shrubby plant, abundant in east Kenya, Gynandropsis gynandra (L.) Brig., was shown to exhibit repellent and acaricidal properties to larvae, nymphs and adult Rhipicephalus appendiculatus and Amblyomma variegatum ticks. All stages of ticks avoided the leaves of the plant and a high percentage of the ticks which were continuously exposed to its leaves died; surviving ticks were weak and inactive but regained activity when exposed to fresh air. The effectiveness of the plant's leaves as a repellent and acaricide was most pronounced on nymphs and least pronounced on adults. Field investigations indicated that ticks were not found up to 2-5 m from the plant in areas where the plant was predominant. The potential of using the plant for tick control within an integrated tick management system in the resource-poor farming context in Africa was highlighted.     

Apparent and standardised ileal amino acid digestibility of wheat distillers dried grains with solubles with or without exogenous protease in broilers and turkeys

1. The apparent (AIAAD) and standardised ileal amino acid digestibility (SIAAD) of wheat distillers dried grains with solubles (wheat-DDGS) was determined for broilers and turkeys at 28 d using two experiments.

2. A total of 84 male Ross 308 broiler chicks (Experiment 1) or 84 male BUT 10 turkey poults (Experiment 2) were offered a nutrient-adequate diet from d 1 to 23. On d 23, birds in each experiment were allocated to 4 treatments consisting of a nitrogen-free diet (NFD) (with or without protease) and an assay diet containing wheat-DDGS as the only source of amino acids (with or without protease) in a randomised complete block design.

3. In Experiments 1 and 2, the coefficient of AIAAD or SIAAD of Lys and Asp were low irrespective of protease. In Experiment 1, the coefficient of AIAAD ranged from 0.35 (Ala) to 0.75 (Pro) without protease, whereas the range was 0.42 (Thr) to 0.82 (Pro) with protease. Protease improved the coefficient of AIAAD for Arg and Pro and tended to improve the coefficient of AIAAD for Met. Without protease, the coefficient of SIAAD ranged from 0.51 (Ala) to 0.84 (Pro), whereas the range was from 0.65 (Ala) to 0.93 (Pro) with protease. Protease improved the coefficient of SIAAD of Arg, Leu, Phe, Met, Val and Pro.

4. In Experiment 2, the coefficient of AIAAD was lower than 0.50 for all amino acids except for Glu (0.70) and Pro (0.81) without protease. On the other hand, the coefficient of SIAAD ranged from 0.41 (Thr) to 0.89 (Pro) without protease, whereas the range was from 0.56 (Arg) to 0.88 (Pro) with protease supplementation. With the exception of Cys and Pro, protease improved the coefficient of AIAAD and SIAAD of all other amino acids by 0.05–0.19.

5. It was concluded that the AIAAD and SIAAD of wheat-DDGS are variable and are generally greater in broilers compared to turkeys at 28 d of age. Protease improved the ileal digestibility of a large number of amino acids in wheat-DDGS for broilers and turkeys.

     

Practices of cattle keepers of southwest Nigeria in relation to bovine trypanosomosis

Tropical Animal Health and Production - Significant increases in human and livestock populations coupled with agricultural practices have changed the socioeconomic perspectives of livestock...     

Studies on ticks of veterinary importance in Nigeria: intrinsic factors influencing oviposition and egg-hatch of Amblyomma variegatum under natural conditions

During the peak of rains of 1983, 1984 and 1985 in the forest zone of Nigeria, female Amblyomma variegatum engorged to various weights were subjected to different experiments for the purpose of observing the intrinsic factors which influence oviposition and egg-hatch under natural conditions. Two types of oviposition patterns were observed. New terms were introduced to quantify the relationships between the daily weight loss and daily number of eggs oviposited by a tick. These terms are "actual mass", "convertible blood mass", "oviposition efficiency" and "mass conversion rate". A major advantage of adopting the "oviposition efficiency" and "mass conversion rate" is that they relate directly to the measure of the metabolic activity utilized by the tick for the process of oviposition. The entity "convertable blood mass" also enables recognition of individual capability in the utilization of blood mass for oviposition. Investigation on the relationship of weight of eggs with sequence of oviposition showed that eggs were heavier when few eggs were laid than when numerous eggs were oviposited. The heaviest eggs were laid towards the end of oviposition. Two types of relationship were found to exit between the sequence of oviposition and the eclosion period of eggs. Adult A. variegatum engorged to more than 2.49 x were affected by immersion in water for longer than 7 days. Such ticks died without ovipositing and the water in which they were submerged became dark-red. Eggs immersed in water for periods ranging from 1-7 days hatched in about the same number of days as control eggs and their viability in terms of percent-hatch was not affected.     

Introgression of whitefly (<Emphasis Type="Italic">Aleurotrachelus socialis</Emphasis>) resistance gene from F<Subscript>1</Subscript> inter-specific hybrids into commercial cassava

The most widespread disease of economic importance of cassava is caused by whitefly vector, both as a single strain or combination of strains. A B₁P₂ family was generated from the crosses of an inter-specific F₁ hybrid (CW 198-11) as a female parent with a commercial cassava cultivar (MTAI-8) as male parent at CIAT headquarters and evaluated in a high-pressure zone for whiteflies in Colombia. 227 genotypes were scored using a scale ranging from 1 (no leaf damage) to 6 (considerable leaf necrosis and defoliation, sooty mould on mid and lower leaves and young stems). The rest were considered promising. The most promising resistance was for damage ratings below 2 for 17.8% of the genotypes. The availability of the pest resistance genotypes, will serve as a means to combat the problem of CMD in Africa provided that resistance to A. socialis is also effective against B. tabaci with different virus strains that is capable of been introduced.     

Isolation and Determination of Polycyclic Aromatic Hydrocarbons in Surface Runoff and Sediments

The distribution of Polycyclic Aromatic Hydrocarbons (PAHs) was investigated in surface runoff and sediments of Lagos, Osogbo and Ile-Ife Western areas of Nigeria. Method for the analysis of PAHs was based on Liquid-Liquid extraction of the runoff and a soxhlet extraction of the sediments followed by a clean up adsorption procedure. The PAHs were separated and quantified by Gas Chromatography-Mass spectrometry (GC-MS) technique. A blank experiment was done using triply distilled water and following the same procedure for the samples to establish blank levels. In both street runoff and sediments 13 PAHs were identified and quantified. At Osogbo and Ile-Ife areas, the mean levels of PAHs in surface runoff ranged between 0.10–15.81 mg L^-1 while in the Lagos area the levels were between 0.1–73.72 mg L^-1. Generally, the PAH levels in surface runoff of Lagos constitute 53.03 mg L^-1 average ∑ PAH detected in the study area compared to 31.96 mg L^-1 average ∑ PAH contribution made by samples from Osogbo and Ile-Ife. The levels of PAHs in sediments are relatively higher compared to those of the street runoff in the study area. PAHs in sediment of Lagos contribute an average of 228.57 mg kg^-1 ∑ PAH to the total sediment PAH burden compared to Osogbo and Ile-Ife areas that contribute only 91.13 mg kg^-1 average ∑ PAH to the total PAH burden of the study area. The relatively higher average ∑ PAHs reported for Lagos area compared with those of Osogbo and Ile-Ife, is consistent with higher industrial activities and traffic density of the former (1000–10000 vehicles/hr) than the later (450–1500 vehicles/hr).     

Studies on naturally acquired immunity to African ticks. II. Observations on cattle exposed to Rhipicephalus appendiculatus under varying periods of repeated infestations.

Groups of Friesian cattle were infested repeatedly with Rhipicephalus appendiculatus at weekly intervals (eight infestations) and at intervals of 3 weeks (seven infestations) and 6 weeks (seven infestations). The engorgement weight of adults, nymphs and larvae decreased significantly initially, from the second infestation, but rose significantly at later infestations. This rise was more dramatic with larval instars than with any other. A new method for quantifying the resistance status of animals was introduced; this method showed that the resistance acquired by cattle during 6-weekly reinfestations was more stable than that acquired by cattle during weekly and 3-weekly reinfestations. The criteria for assessing natural resistance to ticks was reappraised. These are classified into those serving long- and short-term purposes, and those which have direct and indirect effects. Criteria which could serve long- and short-term purposes include a reduced number of engorged ticks, an increased number of dead male and female ticks, a decreased number of ticks which fed above the critical engorgement weight and an increased number which fed within the pre-mating weight and decreased the number of copulations. The criterion of reduced engorgement weight can serve the short-term purpose only. A new manifestation of resistance to ticks, i.e. decreased moulting weights of nymphs and adults, together with the criterion of decreased egg hatchability, were classified as indirect effects because they were manifested after the ticks had dropped off the resistant cattle.     

Suspected resistance of Trypanosoma species to diminazene aceturate on a cattle farm in Nigeria

Tropical Animal Health and Production - African animal trypanosomiasis is a major cause of mortality and economic losses for the livestock industry in Nigeria. Chemotherapy has been the most...     

Comparative insecticidal activity of cypermethrin and cypermethrin-mix applications against stomoxyine vectors

Tropical Animal Health and Production - Stomoxyines are mechanical vectors of several pathogens of livestock with severe consequences such as low productivity from constant irritation and...     

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.