Determinants of herbaceous plant species composition on a number of ranches in the north‐western Transvaal

Herbaceous plant species composition was measured on ranches in the Thabazimbi district, Transvaal, to obtain veld composition scores and to quantify the relations between such scores and certain determinants considered important in influencing species composition. Determinants investigated were mean annual rainfall and herbivory (stocking rate). The survey was undertaken on seven game and cattle ranches in Combretum apiculatum woodland of the Mixed Bushveld (Acocks 18) of the north‐western Transvaal. Rainfall for the season preceding the vegetation survey and bulk and selective grazer stocking rates had a significant effect on veld composition scores. The recommended agricultural grazer stocking rate for the survey area is 12.5 LSU 100 ha"¹ a"¹. Under the present conditions and in view of the findings of this survey, it is suggested that a grazer stocking rate of 6.25 LSU 100 ha^?1 a^?1 be implemented.     

Die invloed van bemesting op die spesiesamestelling en basale bedekking van beweide veld in die Potchefstroom‐omgewing

The impact of fertilization on veld in the Potchefstroom area was investigated. Nitrogen and phosphorus were applied annually from 1972/73 until 1981/82. The control plots and the fertilized plots were grazed with year‐old steers. Species composition and basal cover were recorded using the wheelpoint technique. The results clearly indicated the formation of a soil fertility gradient as a result of the fertilization. Although there was a decrease in the ecological status of the fertilized plots, the production and palatability of the sward increased and thus also animal performance.     

The influence of nitrogen and defoliation on production and water‐use efficiency of Lolium multiflorum cv. Midmar

Abstract

The objective of this study was to investigate the influence of different nitrogen fertiliser application levels in combination with different defoliation intervals on the dry matter (DM) production and water‐use efficiency of ryegrass (Lolium multiflorum,) cv. Midmar. In a field trial, four nitrogen levels (0, 150, 300 and 450 kg N ha^?1) were combined with five defoliation intervals (every 2, 4, 6 and 8 weeks and twice a season). Soil moisture levels were measured with a neutron hydroprobe and were used to schedule irrigation. The dry matter production, nitrogen‐use efficiency (NUE), plant DM content and water‐use efficiency were influenced (P<0.01) by nitrogen level, defoliation interval, and the interaction between these factors. Total DM production varied from 64 to 20 922 kg DM ha^?1. Dry matter production per unit of applied N decreased with an increase in N level within a defoliation interval. The plant DM content varied from 14.0% to 35.6%. The plant DM content decreased (P<0.05) with increasing N applications, while a lengthening of the defoliation interval resulted in an increase (P<0.05) in the DM content. No difference (P>0.05) was found in total water used when plants received N. Water‐use efficiency varied from 1.2 to 25.8 kg DM ha^?1 mm^?1 water received.     

Research note: Evaluation of the reliability of local farmer knowledge in Namaqualand,South Africa

Abstract

Local farmer knowledge of species distribution patterns and plant palatability in Namaqualand, South Africa, was assessed using Participatory Rural Appraisal techniques. These findings were compared with the results obtained using phytosociological techniques (species distribution), and with palatability indices published in the literature. It was found that farmers were knowledgeable of species distribution close to the settlement, but less so further away from the settlement. Farmer plant palatability rankings did not correlate well with the palatability indices found in the published literature, which suggests that palatability in semi‐arid regions are locality specific.     

Factors affecting the voluntary feed intake of sheep grazing Pennisetum clandestinum (kikuyu) pastures: Observations from forage analysis

Abstract

Sheep were used in two investigations to study factors which could limit voluntary intake of Pennisetum clandestinum (kikuyu) pasture. Possible reasons for the low intakes were found in the high soluble nitrogen and nitrate content of the pasture, its high oxalate content, and its considerable potential for foaming, the latter suggesting the presence of sapbnins. The high fibre content of the material could also have limited intake in wilted, dry or stemmy kikuyu. The relative importance of these factors appears to change with growth stage, the amount of nitrogen fertilizer applied, stocking rate and moisture supply. The factors which are detrimental to forage quality such as oxalates and nitrates are higher in the young and actively growing material than in older material, while the in vitro production of foam seems unrelated to forage quality and remained high, despite changes in other factors which detrimentally affected forage quality.     

RADIOGRAPHIC FEATURES OF PRIMARY AND CONCOMITANT FLEXOR ENTHESOPATHY IN THE CANINE ELBOW

Primary flexor enthesopathy is a recently recognized elbow disorder and should be considered in the differential diagnosis of elbow lameness. For treatment planning purposes, it is important to make a distinction between primary and concomitant forms of the disease. The purpose of this prospective study was to compare radiographic findings for dogs with primary flexor enthesopathy (n = 17), concomitant flexor enthesopathy (n = 24), elbow dysplasia (n = 13), and normal dogs (n = 7). All dogs underwent a complete radiographic examination and each radiographic image was evaluated for the presence or absence of following characteristics: irregular medial humeral epicondyle, spur and calcified body. Additionally, the presence or absence of other elbow disorders (medial coronoid process disease, osteochondritis dissecans, ununited anconeal process, incongruity, subtrochlear sclerosis, and osteoarthritis) was recorded. Radiographic characteristics of flexor enthesopathy were found in 86% of painful joints in the primary flexor enthesopathy group and in 100% of painful joints in the concomitant flexor enthesopathy group. Radiographic characteristics of flexor enthesopathy were not found in sound elbow and elbow dysplasia groups. Frequencies and details of individual radiographic characteristics did not differ between primary and concomitant flexor enthesopathy groups. Findings support the use of radiography as a first screening method for detection of flexor enthesopathy, but not as a technique for distinguishing primary vs. concomitant forms.     

Risk factors for insect bite hypersensitivity in Friesian horses and Shetland ponies in The Netherlands

Insect bite hypersensitivity (IBH) is an equine skin allergy caused by bites of Culicoides spp. and impacts on the welfare of affected horses. The aim of this study was to identify and quantify risk factors for IBH. Data from 3453 Friesian horse mares and 7074 Shetland pony mares scored for IBH by inspectors during obligatory foal inspections were analysed using breed-specific multivariable logistic regression models. The combined effect of month and year of scoring, Province and inspector were significantly associated with IBH in both breeds. In Shetland pony mares, withers height and coat colour were also significantly associated with IBH, while body condition had a nearly significant effect. The outcomes from this study on risk factors might contribute to the development of more efficient measures to reduce the prevalence of IBH.     

Serotype- and serogroup-specific detection of African horsesickness virus using phage displayed chicken scFvs for indirect double antibody sandwich ELISAs

There is an ongoing need for standardized, easily renewable immunoreagents for detecting African horsesickness virus (AHSV). Two phage displayed single-chain variable fragment (scFv) antibodies, selected from a semi-synthetic chicken antibody library, were used to develop double antibody sandwich enzyme-linked immunosorbent assays (DAS-ELISAs) to detect AHSV. In the DAS-ELISAs, the scFv previously selected with directly immobilized AHSV-3 functioned as a serotype-specific reagent that recognized only AHSV-3. In contrast, the one selected with AHSV-8 captured by IgG against AHSV-3 recognized all nine AHSV serotypes but not the Bryanston strain of equine encephalosis virus. Serving as evidence for its serogroup-specificity. These two scFvs can help to rapidly confirm the presence of AHSV while additional serotype-specific scFvs may simplify AHSV serotyping.     

Annual reproductive pattern in the dassie Procavia capensis

Proximate factors influencing the reproductive pattern and rate in dassies are examined in an area subject to marked seasonal climatic variation. The influence of photoperiod is confirmed with no modifying influence by either temperature or rainfull during the period of the study. Testicular and ovarian activity was related, showing a peak in ovulation and fertilization between the period mid-March and mid-April. Of 49 pregnant females collected between June and December, 83% had either two or three embryos/fetuses. Growth curves for differing litter sizes have been calculated. Failure to increase litter size appears to be related more to a conservative ovulation rate than to ova not fertilized or fetal wastage, although ova loss increased with increasing ovulation rate.