Waarnemings oor die voorkoms van bronstigheid by Afrikaner en Jerseykoeie onder ekstensiewe toestande in Noord-Kaapland

Gedurende die uitvoering van twee kruisteeltprojekte te Vaalhartslandbounavorsingstasie is inligting verkry in verband met die voorkoms van bronstigheid tydens 'n geslote dekseisoen by Afrikaner- en Jerseykoeie. Vir vyf agtereenvolgende jare is waarnemings gedoen op 'n kudde van ongeveer 270 Afrikaner en 75 Jerseykoeie. Oor genoemde periode het uit 'n totaal van 1297 Afrikaner- en 357 Jerseykoeie, 80,3 en 94.7% onderskeidelik waarneembare estrus getoon. Dit was veral lakterende Afrikanerkoeie en by uitstek die met hul eerste kalf wat geneig het tot 'n lang post partum anestrusperiode. Slegs 55,9 %van laasgenoemde groep het tydens die dekseisoen waarneembare estrus getoon teenoor 86.2% by dieselfde groep Jerseys. Die Jerseykudde is egter van 'n energielek voorsien gedurende kritieke voedingstoestande wat wel 'n effek kon gehad het. Afrikaners het 60.3 %van die waargenome bronsperiodes in die vroee oggend getoon teenoor 39,7 %in die laat namiddag. Ooreenstemmende data by die Jersey was 59,0 en 41,0%onderskeidelik vir die twee waarnemingstye, Van 543 voltooide estrussiklusse by die Afrikaner was 57,1 %binne die normalc grense (18 -23 dae) teenoor 53,6 %van 194 siklusse by die Jerseys. Siklusse korter as 18 dae het in 22.1 % van die gevalle by die Afrikaner voorgekom teenoor 32,5 %by die Jerseys. Die gemiddelde lengte van normale siklusse was 20,53 en 20.35 dae by die Afrikaner en Jersey onderskeidelik.English Title: Observations on the occurrence of oestrus in Africander and Jersey cattle under extensive conditions in the Northern CapeEnglish AbstractData concerning the occurrence of oestrus in Africander and Jersey cattle under extensive conditions were obtained from a crossbreeding program at Vaalharts Agricultural Research Station. Observations were made during the annual two and a half month breeding season on a herd of approximately 270 Africander and 75 Jersey cattle for five consecutive years. During this period oestrus was observed in 80,3 % of 1297 Africander and in 94,7 % of 357 Jersey cows. The occurrence of a relatively long post partum anoestrous period was evident in lactating Africander cows, especially those with the first calf at foot. Only 55,9 %of the latter exhibited oestrus during the breeding season compared to 86,2 %of their Jersey counterparts. The Jersey herd, however, received an energy lick during critical nutritional periods which may have had some effects. Amongst the Africanders, 60,3 % of the observed oestrous periods were first noted during the early morning and 39,7 % in the late afternoon. The corresponding percentages for the Jersey females were 59,0 and 41,0 %respectively. Of the 543 completed oestrous cycles recorded in the Africander herd, 57,1 % were within the normal acceptable limits (18-23 days) as against 53,6 %of the 194 completed cycles of the Jerseys. A cycle length of less than 18 days was recorded in 22,1 and 32,5 % of the observations amongst the Africanders and Jerseys respectively. The average length of normal oestrous cycles was 20,53 days in the Africander against 20,35 days in the Jersey

The abundance of an invasive freshwater snail Tarebia granifera (Lamarck, 1822) in the Nseleni River, South Africa

The invasive freshwater snail Tarebia granifera (Lamarck, 1822) was first reported in South Africa in 1999 and it has become widespread across the country, with some evidence to suggest that it reduces benthic macroinvertebrate biodiversity. The current study aimed to identify the primary abiotic drivers behind abundance patterns of T. granifera, by comparing the current abundance of the snail in three different regions, and at three depths, of the highly modified Nseleni River in KwaZulu-Natal, South Africa. Tarebia granifera was well established throughout the Nseleni River system, with an overall preference for shallow waters and seasonal temporal patterns of abundance. Although it is uncertain what the ecological impacts of the snail in this system are, its high abundances suggest that it should be controlled where possible and prevented from invading other systems in the region

Modeling top-down and bottom-up drivers of a regime shift in invasive aquatic plant stable states

FWN – Publicaties zonder aanstelling Universiteit Leide

Monoclonal antibody characterization of South African field isolates of Haemophilus paragallinarum

A total of 27 different isolates of Haemophilus paragallinarum were made from chickens between June 1991 and December 1992. All of these isolates were examined by ELISA, by means of a locally produced panel of three monoclonal antibodies (denoted F1 , V1 and VF3). The isolates were all of the F1 antigenic type. Three of them showed a weak reaction with the F1 monoclonal antibody, while three other isolates reacted strongly with the F1 as well as with the VF3 Mab. A selection of stored Haemophilus isolates, dating from 1984 to 1985, were also examined with the Mabs and found to be of the F1 antigenic type. Fifteen isolates were collected before 1974, i.e. before the use of Haemophilus vaccines in this country. The majority of them were of the F1 antigenic grouping. Some showed a weak reaction with the F1 Mab; others showed a strong reaction with both the F1 and VF3 Mabs; and a few showed no significant reaction with any of the Mabs used. Strains used for the production of infectious coryza vaccine were also examined with the Mabs. Strain 0083 showed a stronger reaction with the V1 Mab than with the F1 Mab, whereas strain 0222 showed no reaction with any of the Mabs. None of the SA field isolates collected since the use of vaccines exhibits the V1 antigenicity, which is the prevalent antigen of strain 0083. Most (80%) of the SA field isolates showed a stronger reaction with the F1 Mab than did strain 0083. Antigenically silent isolates similar to 0222 (Page's serotype B) were isolated before the use of vaccines, but not since.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.South African Cancer Association. Egg Board.mn201

African swine fever. I. Morphological changes and virus replication in blood platelets of pigs infected with virulent haemadsorbing and non-haemadsorbing isolates

Replicating and mature viral particles were detected with the transmission electron microscope in blood platelets of pigs infected with virulent haemadsorbing and non-haemadsorbing African swine fever virus isolates. Although platelet numbers decreased terminally in infected pigs, the most noticeable morphological damage to these cells apparent in the last 2 days of the disease included cytoplasmic swelling, vacuolation, fragmentation and loss of dense granules.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Plasmid-encoded NAD independence in some South African isolates of Haemophilus paragallinarum

Atypical Haemophilus paragallinarum have been isolated from both laying hens and broilers suffering from typical symptoms of infectious coryza in South Africa. Re-inoculation of these bacteria into SPF chickens resulted in similar pathology. The bacteria could be successfully re-isolated from the experimentally infected chickens. Four of the isolates from layers and 3 of those from broilers were found to be closely related to H. paragallinarum serotype A (0083 strain) when tested by the use of a panel of locally developed monoclonal antibodies in the enzyme linked immunosorbent assay (ELISA) . A total of 15 isolates from layers and 19 from broilers were found to be more typical of previously collected South African field isolates of H. paragallinarum. A 3rd group, consisting of 5 isolates from layers and 15 from broilers, showed no reaction with the panel of monoclonal antibodies. All the isolates were regarded as atypical because they no longer required V factor (NAD) for growth, whereas strain 0083 and previously collected field isolates M 85 and SB 86 did require it.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.South African Egg Board. National Cancer Association.mn201

Effects of growth conditions and incubation times on the expression of antigens of Haemophilus paragallinarum which are detected by monoclonal antibodies

Haemophilus paragallinarum causes infectious coryza in poultry, and a panel of monoclonal antibodies (Mabs) were established, which detect surface antigens of this bacterium. It was postulated that these Mabs could be used to detect antigenic differences between strains of H. paragallinarum used in infectious coryza (IC) vaccines, and isolates made from the field , from poultry vaccinated against IC. It has previously been reported that in South Africa there are three different Mab patterns that have been common to H. paragallinarum isolates for the past three decades. The effects of different growth conditions such as duration of incubation, inoculum size, levels of NAD or NaCI in the medium, and the pH of the medium on these Mab patterns were investigated. It was found that many different factors appear to influence the expression of the antigens detected by the panel of Mabs. It was found that at different stages during the growth cycles, the isolates could be classified into different Mab groups. It was also found that alteration of the inoculum size resulted in Mab-pattern switches. Addition of extra NaCI to the medium, in order to slow the growth rate, was found to result in Mab-pattern switches. pH was found to have signifcant effects on the levels of expression of the antigens detected by the Mabs, although these changes did not result in Mab-pattern switches. The effects of pH were also found to be highly strain dependent. The use of NAD, rather than sterile chicken serum, in the medium did not significantly alter the levels of expression of these antigens. Alterations of the growth conditions greatly affected the levels of expression of the antigens detected by the Mabs, and were highly strain dependent. It was not possible to predict the effects of a particular growth condition on a particular strain or isolate of H. paragallinarum.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat X Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Changes in the incidences of the different serovars of Haemophilus paragallinarum in South Africa: a possible explanation for vaccination failures

Infectious coryza remains an important disease in the poultry industry despite the long-term and widespread use of vaccines against its causative agent, Haemophilus paragallinarum, in South Africa. In order to detect antigenic changes between populations of H. paragallinarum isolated before the use of vaccines against infectious coryza in this country, and field isolates obtained after the introduction of infectious coryza vaccines, 106 different NAD-dependent isolates (of which 93 were identified as H. paragallinarum) from 63 different farms, and dating from 1972 to March 1995, were identified by means of rabbit antisera against serogroups A, B and C. Serogroup C isolates show weaker cross-protection, requiring the further subdivision of this serogroup into its four different serovars. The percentages of the different serovars obtained in the 1970s, confirmed previously published data on South African isolates. A tendency towards a decrease in the number of serogroup A and serovar C-2 isolates, and an increase in the percentage of serovar C-3 isolates, was noted among isolates of the 1980s. These changes were markedly enhanced in the isolates obtained from 1990 to March 1995. The percentage of serogroup A isolates decreased significantly from 34% in the 1970s to only 5% in the 1990s, and that of serovar C-2 isolates, from 31-18%, while the abundance of serovar C-3 isolates increased significantly from 31% in the 1970s to 73% in the 1990s. Serogroup B remained more or less constant and never reached more than 10% of the population. These results indicate the need for the incorporation of serovar C-3 in a vaccine for use in South Africa, particularly in those areas of the country from which isolates were collected during this study. Some of the NAD-dependent isolates obtained from poultry in South Africa between 1970 and 1995, were biochemically identified as Pasteurella avium and P. volantium. As H. avium has been subdivided and reclassified into the genus Pasteurella, this represents the first report of the identification of P. avium and P. volantium in South Africa.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat X Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), a potential biological control agent for the submerged aquatic weed, Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae)

The leaf-mining fly, Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), was investigated in its native range in South Africa, to determine its potential as a biological control agent for Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae), an invasive submerged macrophyte that is weedy in many parts of the world. The fly was found throughout the indigenous range of the plant in South Africa. High larval abundance was recorded at field sites with nearly all L. major shoots sampled ontaining larvae, with densities of up to 10 larvae per shoot. Adults laid batches of up to 15 eggs, usually on the abaxial sides of L. major leaves. The larvae mined internally, leaving the epidermal tissues of the upper and lower leaves intact. The larvae underwent three instars which took an average of 24 days and pupated within the leaf tissue, from which the adults emerged. Impact studies in the laboratory showed that H. lagarosiphon larval feeding significantly restricted the formation of L. major side branches. Based on its biology and damage caused to the plant, Hydrellia lagarosiphon could be considered as a useful biological control candidate for L. major in countries where the plant is invasive

Effects of transformation on the hemagglutinins of Haemophilus paragallinarum

Strain 0083 and two field isolates of H. paragallinarum were previously converted into NAD-independent organisms by the use of crude DNA extractions from naturally occurring NAD-independent H. paragallinarumisolates. Two of these transformed isolates [0083(T) and A745(T)] were used as DNA donors in another transformation experiment in which another field isolate (M85) was used as the DNA recipient. Transformation was confirmed by lack of NAD requirement for growth, by carbohydrate fermentation patterns and by a comparison of the monoclonal antibody patterns of the isolates before and after transformation. Previously, antigenic differences were observed when DNA from an NAD-independent isolate was introduced into strain 0083. Antigenic differences were also seen in the transformed M85 organisms prepared in this work, and these differences were dependent on the antigenic patterns of the DNA donors. It was established by haemagglutination (HA) and haemagglutination inhibition (HI) that the hemagglutinins of 0083, A745/92 and M85 were not affected by transformation. The use of strains transformed to NAD independence for vaccine production appears to be a valid approach, as the transformation appears not to affect the hemagglutinins of the transformed organisms. The major advantage would be the alleviation of the requirement for chicken serum or NAD in the bacterial growth medium used for infectious-coryza-vaccine production.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201