Effects of 'Agri-SC' soil conditioner on soil structure and erodibility: some further observations

Abstract. In field and laboratory experiments the conditioner‘Agri-SC’has shown improvements in the structure of loamy sand soils in east Shropshire, UK. It resulted in statistically significant decreases in soil bulk density values and increases in soil porosity and aggregate stability. Further experiments are in progress on both loamy sand and silt loam soils.     

Protection of chickens from Newcastle and Marek's diseases with a recombinant herpesvirus of turkeys vaccine expressing the Newcastle disease virus fusion protein.

Recombinant strains of herpesvirus of turkeys (HVT) were constructed that contain either the fusion protein gene or the hemagglutinin-neuraminidase gene of Newcastle disease virus (NDV) inserted into a nonessential gene of HVT. Expression of the NDV antigens was regulated from a strong promoter element derived from the Rous sarcoma virus long terminal repeat. Recombinant HVT strains were stable and fully infectious in cell culture and in chickens. Chickens receiving a single intra-abdominal inoculation at 1 day of age with recombinant HVT expressing the NDV fusion protein had an immunological response and were protected (> 90%) against lethal intramuscular challenge at 28 days of age with the neurotropic velogenic NDV strain Texas GB. Recombinant HVT expressing the NDV hemagglutinin-neuraminidase provided partial protection (47%) against the same challenge. Chickens vaccinated with recombinant HVT vaccines had low levels of protection against NDV replication in the trachea when challenged ocularly. Recombinant HVT vaccines and the parent HVT strain provided similar levels of protection to chickens challenged with the very virulent RB1B strain of Marek's disease virus, indicating that insertion of foreign sequences into the HVT genome did not compromise the ability of HVT to protect against Marek's disease.     

Weed management strategies for the control of Rottboellia cochinchinensis in maize in Trinidad

Summary. A weed management strategy for the control of Rottboellia cochinchinensis (Lour.) W.D. Clayton in maize, based on reducing the level of spikelet germination from the seedbank and reducing the intensity of weed-crop interference, was conducted over two seasons. The management practices evaluated included chemical control (atrazine, metolachlor, pendimethalin, EPTC), cultural control (straw mulch), mechanical control (inter-row cultivation) and biological control (living mulch). The results indicated that the various management practices had no effect on the growth and development of the crop but significantly affected the weed. The pendimethalin (1°5 kg a.i. ha⁻¹) and inter-row cultivation (14 and 28 days after planting) treatments gave satisfactory control of the weed in the crop over the duration of the critical period of weed competition. All other treatments were ineffective. All management practices made significant contributions to the weed seedbank, thus ensuring the predominance of the weed.     

Factors affecting the cropping potential of reinstated soils

Abstract. Comparisons of crop production on recently reinstated soil in Northumberland have shown that the reduced yield potential of such soil may not be inevitable. Storage of soil in bunds did not greatly reduce subsequent crop yields, but failure to drain the land did. Provided an effective drainage scheme was installed, arable and grass crops could be grown successfully, responding very well to additions of nitrogen fertilizer and other normal good husbandry practices. To date it seems that neither deep cultivation nor the use of grass leys were as effective in the restoration process as had been expected.     

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.     

EPW: A procedure for the functional assessment of planned wetlands

The practice of compensating wetland losses through wetland construction, restoration, or enhancement has become more commonplace; however, an appropriate method for assessing replacement of wetland function has been lacking. The Evaluation for Planned Wetlands (EPW) was developed to meet this need. It is a rapid assessment procedure which documents and highlights differences between a wetland assessment area and planned wetland based on their capacity to provide six functions: shoreline bank erosion control, sediment stabilization, water quality, wildlife, fish (tidal, non-tidal stream/river, and non-tidal pond/lake), and uniqueness/heritage. The differences between wetlands are expressed in terms of individual elements. Functional Capacity Indices, and Functional Capacity Units. The results provide information on individual design elements and measures of functional capacity which are a necessity under current regulatory programs that require tangible goals and a method for calculating planned wetland size. EPW includes functional assessment models, a procedure for using these models during the planning/mitigation process, and guidelines for functional design.     

Effect of porcine somatotropin on number of granulosa cell luteinizing hormone/human chorionic gonadotropin receptors, oocyte viability, and concentrations of steroids and insulin-like growth factors I and II in follicular fluid of lean and obese gilts.

Prepubertal gilts of obese (n = 24) or lean (n = 24) genetic lines were injected (s.c.) daily with 0, 2, or 4 mg of porcine somatotropin (pST) for 6 wk starting at 160 d of age to determine whether pST affects follicular function. Blood and ovaries were collected at slaughter 24 h after the last injection. Surface follicles greater than or equal to 1.0 mm in diameter were counted, and pools of follicular fluid (FFL) and granulosa cells were collected from 1.0- to 3.9-mm (small) and 4.0- to 6.9-mm (medium) follicles. Oocytes were collected from small and medium follicles and evaluated for maturational stage and viability. Porcine somatotropin increased (P less than .08) the numbers of small but not the numbers of medium follicles per gilt (P greater than .10). Oocyte maturation and viability were not affected by pST or genetic line. Porcine somatotropin increased (P less than .05) concentrations of insulin-like growth factor I (IGF-I) in serum and FFL of both obese and lean gilts; IGF-I was lower (P less than .01) in lean gilts. Treatment with pST decreased (P less than .05) IGF-II in FFL of lean but not in that of obese gilts. Dose of pST and line had no effect on concentrations of progesterone in FFL of small or medium follicles or on concentrations of estradiol in FFL of small follicles.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experimental Yersinia enterocolitica placentitis in sheep.

A strain of Yersinia enterocolitica of O serogroup 6,30 isolated from the liver of an aborted ovine fetus was inoculated intravenously into a group of pregnant ewes at about 90 days gestation and produced placentitis with abortion or delivery of infected lambs about 50 days later. Y. enterocolitica of the same serogroup was recovered from the necrotic placental cotyledons and most other fetal tissues and could be isolated from vaginal discharges of the ewes for a least 2 weeks after abortion. Histological changes were consistent with an acute bacterial necrotizing placentitis and systemic infection of the fetus. Subsequent pregnancies in the ewes proceeded to term without evidence of infection.     

Onchocerca gutturosa and Onchocerca lienalis in cattle: variation in length of microfilariae by site of recovery

Dermal microfilariae recovered from specimens obtained from umbilical and cervical sites of cattle infected with adult Onchocerca gutturosa alone or with adults of O gutturosa and O lienalis were measured and compared with uterine microfilariae obtained directly from gravid female worms of each species. Uterine microfilariae of O gutturosa were longer than dermal microfilariae obtained from cattle harboring only adults of O gutturosa. Dermal microfilariae were recovered from umbilical and cervical sites in these cattle. Those found at the cervical site had lengths equal to or greater than lengths of microfilariae recovered from the umbilical site. There was a significant (P less than 0.0001) shift in length across populations of microfilariae of O gutturosa from various sites in its bovine host, with a progressive decrease in length between microfilariae recovered from the worm's uterus, microfilariae from the cervical dermis, and microfilariae from the umbilical dermis, respectively. A similar direct comparison was not possible for microfilariae of O lienalis, because none of the cattle was infected with only adult worms of this species. In an indirect comparison, microfilariae of O lienalis were identified at the umbilicus, but their presence in the cervical region could not be determined unequivocally because of confounding of microfilariae length by concurrent infection with O gutturosa. Uterine microfilariae from O lienalis were longer than uterine microfilariae of O gutturosa, although a degree of overlap in the range of measurements existed between species.     

Chemotherapy of T b brucei infection: Use of DFMO, diminazene aceturate, alone and in combination

The therapeutic activity of diminazene aceturate, difluoromethylornithine (DFMO) and a combination of the two agents was investigated in experimental Trypanosoma brucei brucei infections in mongrel dogs. The criteria used in the assessment of the trypanocidal effect of these compounds included the examination of the blood for the parasite, as well as clinical and haematological changes at intervals following treatment. Diminazene aceturate (7 mg/kg intramuscularly), DFMO (300 mg/kg/day orally in three divided doses for six days) and the combination of diminazene aceturate (7 mg/kg intramuscularly) and DFMO (300 mg/kg/day orally for six days) produced an intermittent aparasitemia in the dogs. Relapse infection occurred in all the three groups, but the period of aparasitemia produced by the combination of the agents was longest. The packed cell volume, haemoglobin concentration and red cell count values decreased after the dogs were inoculated with the parasite. The values improved slightly following the treatments with the agents or their combination. The total white blood cell counts in the infected dogs indicated leucocytosis, but this improved with drug treatment.