2000 Onderstepoort Journal of Veterinary Research, Volume 67, 2000

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CONTENTS

*Volume 67: Number 1*

A check-list of the nematode parasites of South African Serpentes (snakes) and Sauria (lizards)	Boomker, JDF & Hering-Hagenbeck, SFBN	1

A newly developed odour-baited "H trap" for the live collection of Glossina brevipalpis and Glossina austeni (Diptera: Glossinidae) in South Africa	Kappmeier, K	15

Investigation of biological samples for monofluoroacetate and Dichapetalum cymosum poisoning in southern Africa	Minnaar, PP, McCrindle, RI, Naude, TW & Botha, CJ	27

Parasites of South African wildlife. XVI. Helminths of some antelope species from the Eastern and Western Cape Provinces	Boomker, JDF, Horak, IG, Booyse, DG & Watermeyer, R	31

Suspected sheep-associated malignant catarrhal fever in a zero-grazed dairy herd in Kenya	Mulei, CM, Gathumbi, PK & Mbuthia, PG	43

Oribatid mites (Acari, Oribatida) as intermediate hosts of tapeworms of the Family Anoplocephalidae (Cestoda) and the transmission of Moniezia expansa cysticercoids in South Africa	Schuster, R, Coetzee, L & Putterill, JF	49

Leishmania major infections in Phlebotomus duboscqi fed on murine models immunized with L. major subcellular antigens and sandfly gut antigens	Mbati, PA, Anjili, CO, Odongo, S, Ogaja, P & Tonui, W	57

Research communications:

The prevalence of different African horsesickness virus serotypes in the Onderstepoort area near Pretoria, during an outbreak of African horsesickness in South Africa in 1995/1996	Bremer, CW, Gerdes, GH, Aitchison, H, Louw, I, Greyling, RR & Welgemoed, J	65

Suggested dosage rates of melarsoprol in the treatment of mice experimentally infected with Trypanosoma brucei gambiense	Mbati, PA, Hirumi, K, Inoue, N, Situakibanza, NH & Hirumi, H	71

Helminth parasites of domestic pigeons (Columba livia domestica) in Sebele, Gaborone, Botswana	Mushi, EZ, Binta, MG, Chabo, RG, Ndebele, R & Panzirah, R	75

Guide for authors		77


*Volume 67: Number 2*

Evaluation of a commercially available ELISA kit for detection of antibodies to Anaplasma marginale and Anaplasma centrale in cattle in Australia and Zimbabwe	Bowles, PM, Molloy, JB, Blight, GW,Singh, S & Mabikacheche, LG	83

The effect of a natural maedi-visna virus infection on the productivity of South African sheep	Dungu, B, Vorster, J, Bath, GF & Verwoerd, DW	87

Stability and partitioning of closantel and rafoxanide in ruminal fluid of sheep	Swan, GE, Oliver, DW, Van Rensburg, J, Steyn, HS & Mulders, MSG	97

Morphological changes associated with the development of the rumino-reticulum in growing lambs fed different rations	Groenewald, HB & Swan, GE	105

The rise and fall of tuberculosis in a free-ranging chacma baboon troop in the Kruger National Park	Michel, AL, Keet, DF, Kriek, NPJ, Bengis, RG & Grobler, DG	115

Biochemical and haematological changes in rats administered an aqueous extract of Prunus africana stem-bark at various dosage levels	Gathumbi, PK, Mwangi, JW, Njiro, SM & Mugera, GM	123

Phage types of Salmonella enterica serovar Enteritidis isolated in South Africa from 1991-1995	Mare, L, Van der Walt, ML & Dicks, LMT	129

Observations on a lesser-known monogenean, Udonella myliobati, from a copepod parasite, Lepeophtheirus natalensis, parasitizing the spotted ragged-tooth shark, Carcharias taurus, from South African waters	Olivier, PAS, Dippenaar, SM, Khalil, LF & Mokgalong, NM	135

Selected chemical parameters in the blood and metals in the organs of the Nile crocodile, Crocodylus Niloticus, in the Kruger National Park	Boomker, JDF, Swanepoel, D & Kriek, NPJ	141

Research communications:

Oral infectivity of cryopreserved Haemonchus contortus infective larvae that recovered relatively slowly when thawed after more than 15 years in liquid nitrogen	Van Wyk, JA & Gerber, HM	149

Occurrence of Neodiplozoon polycotyleus Paperna, 1973 (Diplozoidae: Monogenea) in cyprinid fish in South Africa	Mashego, SN	153

Book review		155


*Volume 67: Number 3*

The role of parasitic diseases as causes of mortality in cattle in a high potential area of central Kenya: a quantitative analysis	Kanyari, PWN & Kagira, J	157

Models for regional heartwater epidemiology in a variable environment	Levins, R	163

The distribution of tsetse (Diptera: Glossinidae) and bovine trypanosomosis in the Matutuine District, Maputo Province, Mozambique	Van den Bossche, P, Neves, LCBGD, Sigauque, I, Moiana, M & Jamal, S	167

Molineus cati n. sp. (Nematoda, Trichostrongylina, Molineoidea), a parasite of feral cats, Felis catus Linnaeus, 1758 in South Africa	Boomker, JDF, Durette-Desset, MC & Malan, FS	173

Diurnal activity patterns of Glossina brevipalpis and G. austeni (Diptera: Glossinidae) in South Africa, with reference to season and meteorological factors	Kappmeier, K	179

Ultrastructural study of the luminal surface of the ducts of the epididymis of gallinaceous birds	Aire, TA & Josling, D	191

Aerobic intestinal flora of wild-caught African dwarf crocodiles Osteolaemus tetraspis	Huchzermeyer, FW, Henton, MM, Riley, J & Agnagna, M	201

The influence of Mannheimia haemolytica A1 seed culture inoculum cell density on the production of leukotoxin in submerged culture supernatant	Du Plessis, L & Odendaal, MW	205

Research communications:

The prevalence of internal and external parasites in pigs of different ages and sexes in Southeast District, Botswana	Nsoso, SJ, Mosala, KP, Ndebele, RT & Ramabu, SS	217

Bovine borreliosis in Botswana	Sharma, SP, Amanfu, W & Losho, TC	221

Errata		224


*Volume 67: Number 4*

Capsular serogroups of Pasteurella multocida isolated from animals in Zimbabwe	Mohan, K, Pawandiwa, A & Dziva, F	225

Studies on the genus Setaria Viborg, 1795 in South Africa. I. Setaria africana (Yeh, 1959)	Boomker, JDF, Watermeyer, R & Putterill, JF	229

Efficacy of flumethrin 1% pour-on against ticks on cattle under field conditions in Ethiopia	Mekonnen, S	235

Parasites of domestic and wild animals in South Africa. XXXVIII. Ixodid ticks collected from 23 wild carnivore species	Horak, IG, Braack, LEO, Fourie, LJ & Walker, JB	239

Application of ultrasonography in prevalence studies of hydatid cysts in goats in north-western Turkana, Kenya and Toposaland, southern Sudan	Njoroge, EM, Mbithi, PMF, Gathuma, JM, Wachira, TM, Magambo, JK & Zeyhle, E	251

Fertility in rats immunized with steroid-free bovine follicular fluid	Sewani-Rusike, CR & Dakwa, C	257

Parameters for the determination and evaluation of heat stress in dairy cattle in South Africa	Du Preez, JH	263

In vitro erythrophagocytosis by cultured macrophages stimulated with extraneous substances and those isolated from the blood, spleen and bone marrow of Boran and N'Dama cattle infected with Trypanosoma congolense and Trypanosoma vivax	Taiwo, VO & Anosa, VO	273

Differential expression of surface membrane antigens on bovine monocytes activated with recombinant cytokines and during Trypanosoma congolense infection	Taiwo, VO, Anosa, VO & Oluwaniyi, JO	289

Research communications:

Bacterial colonization and endotoxin activity during experimental acute fowl typhoid in chickens	Kokosharov, T	297

Pasteurella gallinarum: Zimbabwean experience of a versatile pathogen	Mohan, K, Dziva, F & Chitauro, D	301

Author index		307

Subject index		317

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Now showing 1 - 20 of 47

Bacterial colonization and endotoxin activity during experimental acute fowl typhoid in chickens
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Kokosharov, T.; Verwoerd, Daniel Wynand
These parameters were assayed by means of colony forming units test (CFU) and the Limulus Amebocyte Lysate test (LAL), respectively. Birds were infected per os with 1,5 x 109 CFU/ml of wild strain of S. gallinarum isolated from a dead hen. Approximately 1,5 x 102; 1,3 x 102 and 1,2 x 102 CFU of S. gallina rum were recorded from 1 g of liver, 1 g of spleen and 1 ml of blood from the chickens on day 1 post infection. By day 4 corresponding data were 3,7 x 104 ; 4,8 x 103 and 1,1 x 103 respectively and on day 7 105 CFU were present in all three specimen types. The liver and spleen of dead birds were contaminated with more than 107 CFU per g. The endotoxin from S. gallinarum was found to have an activity of 1,5; 12,0 and 15,0 endotoxin units (EU)/ml on day 1, 4 and 7 after infection, respectively. No endotoxin activity was established in the blood of the control group (before infection) by the LAL test. This is the first time the connection between the amount of live S. gallina rum in the blood, liver and the circulating level of endotoxin in the blood during the infectious stage of experimental acute fowl typhoid, has been demonstrated.
In vitro erythrophagocytosis by cultured macrophages stimulated with extraneous substances and those isolated from the blood, spleen and bone marrow of Boran and N'Dama cattle infected with Trypanosoma congolense and Trypanosoma vivax
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Taiwo, V.O.; Anosa, V.O.; Verwoerd, Daniel Wynand
A standard radioactive chromium (51 Cr) release assay was used to assess the in vitro phagocytosis and lysis of bovine erythrocytes by cultured splenic, bone marrow and peripheral blood monocytederived (PBM) macrophages isolated from healthy and Trypanosoma congolense and T. vivax-infected cattle of the Boran and N'Dama breeds. Recombinant cytokines (rHuTNF-a and rBoIFN-y) and non-acid-dialysed peripheral blood mononuclear cell (PBMNC) culture supernatants stimulated these PBM for enhanced activities. The stimulants caused increases in the rate of erythrocyte phagocytosis and lysis by cultured PBM in a concentration- dependent manner. But very high stimulant concentrations caused deceased in vitro erythrophagocytosis. However, bacterial lipopolysaccharide (LPS) and acid-dialysed PBMNC culture supernatants did not cause any increase in cultured PBM erythrophagocytosis. In vitro erythrocyte phagocytosis and lysis by splenic, bone marrow and peripheral blood monocyte (PBM)-derived macrophages of Boran breed of cattle infected with Trypanosoma congolense increased from 14 days post-infection (DPI) onwards and thereafter maintained at various levels above pre-infection. Cultured splenic macrophages showed the greatest erythrocyte destruction capability while PBM-derived macrophages was the least. The rates of in vitro erythrocyte phagocytosis and lysis were higher with the cultured PBM of the Beran than those of the N'Dama cattle during T. congolense infection . The rate of in vitro erythrocyte destruction was however, similar in both groups of cattle during T. vivax infection. These results correlated positively with the dynamics and degree of anaemia developed by these groups of animals during both T. congolense and T. vivax infections. Cattle infected with T. congolense and T. vivaxdeveloped varying degrees of normocytic normochromic anaemia during infection. Boran cattle developed a more severe anaemia, and had to be treated with diminazine aceturate, than N'Dama cattle during T. congolense infection. Both breeds of cattle developed a milder but similar degree of anaemia during T. vivax infection. None of the animals were treated. The results of this study indicated a role of in vivo macrophage stimulatory factors, notably cytokines such as TNF-a and IFN-r in host's serum, as well as parasite antigens, which may act singly or in concert, in the process of enhanced erythrocyte destruction, hence anaemia by the mononuclear phagocytic system (MPS) during bovine trypanosomosis.
The prevalence of different African horsesickness virus serotypes in the Onderstepoort area near Pretoria, during an outbreak of African horsesickness in South Africa in 1995/1996
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Bremer, C.W.; Gerdes, Gertruida Hermanna; Aitchison, Henry; Louw, I.; Greyling, Roelf Rudolph; Welgemoed, J.; Verwoerd, Daniel Wynand
During 1995/1996 parts of South Africa experienced exceptionally high rainfall. Large numbers of Culicoides midges were seen and an outbreak of African horse sickness (AHS) followed. In the Onderstepoort area, near Pretoria in Gauteng, a number of horses died of suspected AHS. Virus isolation and typing was done from blood and/or organ samples of 21 suspected cases as well as from 5 zebra which were kept in the area. Virus was isolated from 14 of the 21 suspected cases but not from the zebra. The neutralizing antibody response of the zebra to the nine African horsesickness virus (AHSV) serotypes was determined. Results indicated the highest prevalence of serotypes 2 and 4 followed by serotypes 1, 6 and 9. Reverse transcription polymerase chain reaction (RT-PCR) was performed on total RNA extracted from blood samples of the zebra. AHSV RNA was detected in three of five zebra by agarose gel electrophoresis analysis of amplicons and in four of five zebra after Southern blot hybridization using a 32P-labelled probe. RT-PCR can be used together with serological techniques in studies of AHS to further clarify the epizootiology of the disease.
Author index
(Pretoria : Agricultural Research Council, Onderstepoort Veterinary Institute, 2000) Verwoerd, Daniel Wynand
Pasteurella gallinarum : Zimbabwean experience of a versatile pathogen
(Pretoria : Agricultural Research Council, Onderstepoort Veterinary Institute., 2000) Mohan, K.; Dziva, Francis; Chitauro, D.; Verwoerd, Daniel Wynand
Pasteurella gallinarum-related outbreaks in chickens and African guinea fowls are described. Four outbreaks were recorded in chickens and one in guinea fowls. Periorbital swelling and keratoconjunctivitis were the consistently present clinical signs in all the diseased birds. In several, swollen hocks and wattles were also discerened. Birds which succumbed to the infection showed petechiation in the internal organs and evidence of airsacculitis. Pasteurella gallinarum was isolated from the lesions and also from conjunctival swabs of the apparently healthy in-contact birds. There was no evidence of concurrent infection with Haemophilus, Mycoplasma or Chlamydia. Quinolone therapy when resorted to on one of the farms resolved the clinical signs. Phenotypes of 28 isolates were studied. The results compared well with the Pasteurella gallinarum isolates reported earlier from elsewhere. It was also found that results of xylose fermentation and ONPG test appear to be a variable character. There is no earlier report of P. gallinarum infection in guinea fowls.
Differential expression of surface membrane antigens on bovine monocytes activated with recombinant cytokines and during Trypanosoma congolense infection
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Taiwo, V.O.; Anosa, V.O.; Oluwaniyi, J.O.; Verwoerd, Daniel Wynand
The expression of surface membrane antigens on peripheral blood monocytes (PBM) of cattle of the Boran and N'Dama breeds activated with recombinant cytokines (TNF-α and IFN-γ) and during experimental infection with Trypanosoma congolense was investigated using monoclonal antibodies (MoAbs) and fluorescein-activated cell sorter (FACS). The surface antigens investigated were C3bi receptor, major histocompartibility (MHC) II complex (Ia antigen) and two monocyte/macrophage (MΦ) differentiation antigens. The study revealed that both cytokines caused the enhancement of the expression of all the PBM surface antigens studied. rBoIFN-γ at low concentrations was more efficient in causing the activation of PBM. While the PBM of Boran cattle were more significantly activated to express the C3bi receptor vis-a-vis the Ia antigen than N'Dama cattle, the reverse was the case with the PBM of N'Dama cattle which expressed more Ia antigens than Boran PBM. Similar results were observed during T. congolense infection in the two breeds of cattle. The significantly higher expression of C3bi receptor and correspondingly lower Ia antigen expression by the PBM of Boran cattle, both during trypanosomosis and in vitro may be responsible for the higher rate of erythrocyte phagocytosis, hence the development of more severe anaemia by Boran cattle during trypanosomosis than N'Dama. In addition, the expression of significantly higher numbers of Ia antigen by N'Dama MΦ, hence are more able to process, present and initiate better trypanosome antigen-specific immune response than Boran cattle during infection. These two attributes are known genetic characteristics of trypanotolerance in cattle.
Subject index
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Anonymous; Verwoerd, Daniel Wynand
Bovine borreliosis in Botswana
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Sharma, S.P.; Amanfu, W.; Losho, T.C.; Verwoerd, Daniel Wynand
Clinical Borrelia theileri infection was reported for the first time in cattle from Botswana concurrent with Babesia bovis and Theileria mutans infections. Two animals, an ox and a cow of the Tswana breed demonstrated clinical signs of fever, haemoglobinuria, inappetance, diarrhoea, pallor of mucous membranes, enlarged superficial lymph nodes and rough hair coats. Examination of the blood smears from the affected animals revealed numerous B. theileri, and very few B. bovis and T mutans organisms. Oxytetracycline was administered parenterally to all the animals in the herd. The ox, being extremely weak and recumbent for the previous 4-5 days, succumbed to death the day after the examination. The clearance of spirochaetes from the blood circulation and recovery of the cow three days after treatment with oxytetracycline suggest an involvement of B. theileri in producing clinical disease.
Errata
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Anonymous; Verwoerd, Daniel Wynand
Capsular serogroups of Pasteurella multocida isolated from animals in Zimbabwe
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Mohan, K.; Pawandiwa, A.; Dziva, Francis; Verwoerd, Daniel Wynand
Pasteurella multocida is isolated from a variety of disease conditions from different animal species in our diagnostic laboratory. In order to determine serogroup distribution among the isolates, an indirect haemagglutination test using glutaraldehyde-fixed sheep red blood cells was employed. A serological examination of 79 isolates revealed that 47/79 were of capsular serogroup A, 11/79 capsular serogroup D, 4/79 capsular serogroup B and 17/79 were untypable strains. None of the isolates belonged to either serogroup E or F. All those from cases of classical pasteurellosis could be grouped, but a significantly high proportion of those which originated from companion animals were untypable. The significance of these results is discussed. This report appears to be the first detailed information on the prevalence of various serogroups of P. multocida in animals in southern Africa.
Studies on the genus Setaria Viborg, 1795 in South Africa. I. Setaria africana (Yeh, 1959)
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Watermeyer, Ryno; Putterill, John Fraser; Verwoerd, Daniel Wynand; Boomker, Jacob Diederik Frederik
Setaria africana (Yeh, 1959) is represented by two subspecies, Setaria africana africana Troncy, Graber & Thal, 1976 from giant eland (Taurotragus derbianus) from the Central African Republic and Cameroon and Setaria africana farchai Troncy, Graber & Thal, 1976 from bush buck ( Tragelaphus scriptus), also from the Central African Republic. Material collected from nyala (Tragelaphus angasii), bushbuck and kudu (Tragelaphus strepsiceros) from several localities in the eastern region of South Africa was reexamined. Measurements of adult worms confirmed the differences between the two subspecies and scanning electron microscopy showed that the deirids of S. africana africana are single whereas those of S. africana farchai are double. Setaria africana farchai is recorded for the first time in South Africa.
Efficacy of flumethrin 1% pour-on against ticks on cattle under field conditions in Ethiopia
(Agricultural Research Council, Onderstepoort Veterinary Institute, 2000) Mekonnen, Sileshi; Verwoerd, Daniel Wynand
The efficacy of a flumethrin 1% pour-on (Bayticol, Bayer AH) was evaluated against natural infestations of ticks on cattle on a dairy farm in Ethiopia during 1997/98. The cattle, (n = 92), which were Friesian/ Zebu crosses, were heavily infested with Boophilus decoloratus. Dry cows (n = 8) were randomly selected and allocated either into a treatment or a control group. Flumethrin 1 % pour-on was applied to the treatment group according to the manufacturer's recommendation, i.e. along the dorsal mid-line from the head to the base of the tail. Ticks were counted and identified in situ on treated and control animals. When the total tick counts of the treated group were similar to those on the control, the trial was discontinued. Excellent results were achieved with flumethrin against heavy tick infestations. There was a rapid kill after 24 h post-treatment, and from day 4 onwards 100% control was achieved and maintained for a further 29 days. The results obtained indicate that there was a significant difference between the mean tick counts of the control group compared with those of the treatment group (P < 0,05). The evidence presented here suggests that the flumethrin 1% pour-on may be applied at 45 day intervals and should provide effective protection against the economically important ticks if it is used at the recommended dosage rate and applied correctly.
Parasites of domestic and wild animals in South Africa. XXXVIII. Ixodid ticks collected from 23 wild carnivore species
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Fourie, L.J.; Walker, Jane B.; Verwoerd, Daniel Wynand; Horak, Ivan Gerard; Braack, L.E.O.
Ixodid ticks were collected from 104 wild carnivores belonging to 23 species in various nature reserves and on several farms in all nine provinces of South Africa. Seven feral cats in a nature reserve were also examined. Twenty-four tick species belonging to seven genera were recovered and identified. Amongst these ticks we consider the adults of Haemaphysalis leachi, Haemaphysalis spinulosa, Haemaphysalis zumpti, Ixodes rubicundus, Rhipicentor nuttalli, Rhipicephalus simus and Rhipicephalus turanicus to be true parasites of wild carnivores. Although numerous adult Rhipicephalus appendiculatus and Rhipicephalus zambeziensis were collected from some lions these were either sick or old animals. The immature stages of seven species regularly utilized wild carnivores as hosts on an opportunistic basis.
Application of ultrasonography in prevalence studies of hydatid cysts in goats in north-western Turkana, Kenya and Toposaland, southern Sudan
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Njoroge, E.M.; Mbithi, P.M.F.; Gathuma, J.M.; Wachira, T.M.; Magambo, J.K.; Zeyhle, E.; Verwoerd, Daniel Wynand
A study was done to determine the prevalence of hydatid cysts in goats using ultrasonography. A total of 1 390 goats were examined, 43,6 % (606/1390) of them from north-western Turkana, Kenya and 56,4% (784/1390) from Toposaland, southern Sudan. Hydatid cysts were visualized in 1,82 % (11/606) of the goats from north-western Turkana and 4,34% (34/784) of those from Toposaland. Unlike abattoir surveys, the prevalence data obtained in this study were unbiased because entire flocks were examined. The lower prevalence rate of the disease in goats from Turkana was attributed to the hydatid disease control programme in that area, which is absent in Toposaland .
Fertility in rats immunized with steroid-free bovine follicular fluid
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Sewani-Rusike, C.R.; Dakwa, C.; Verwoerd, Daniel Wynand
Inhibin is a gonadal hormone that inhibits the release of follicle stimulating hormone (FSH) from the anterior pituitary gland. The objective of this study was to determine whether active immunization of male and female rats against inhibin rich, steroid-free bovine follicular fluid would increase inhibin antibody titre, onset of female puberty, pregnancy rate, litter size, testis weights, testosterone concentration and serum FSH. Immunization of rats with steroid free bovine follicular fluid stimulated production of anti-inhibin antibodies that immunoneutralized endogenous inhibins and increased levels of circulating FSH in immunized males. Inhibin immunoneutralization resulted in early vaginal opening in immunized females compared with controls and pregnancy rates were increased when immunized female rats were mated with immunized males. However, serum testosterone, testis weights and potential litter size remained unchanged. We conclude that methods to immunoneutralize inhibin may have merit as therapeutic procedures to enhance reproductive performance in domestic animals.
Parameters for the determination and evaluation of heat stress in dairy cattle in South Africa
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Du Preez, J.H.; Verwoerd, Daniel Wynand
Not all parameters are trustworthy and practical to use as parameters to determine heat stress in dairy cattle. The temperature-humidity index (THI) is still the best, simplest and most practical index (parameter) for measurement of environmental warmth which cause heat stress in dairy cattle. It is practical, easy to determine and relatively trustworthy to use body temperature and respiratory rate as parameters to determine heat stress in dairy cattle. These physiological parameters must always be used together with THI values to determine and evaluate heat stress in dairy cattle. For practical purposes, plasma cortisol concentration and milk composition cannot be used as parameters to determine heat stress in dairy cattle although good indications of acute or chronic heat stress can be obtained. Vanillic acid is a break-down product of adrenalin found in milk, but before its concentration in milk can be used as an indicator/parameter of heat stress in dairy cows, more about the pharmacodynamics of adrenaline in the milk has to be known. Selection and breeding of dairy cows on the basis of their adaptibility to heat stress using the most practical heat stress parameters will ensure that their offspring will have superior performance in the prevailing environmental conditions.
The prevalence of internal and external parasites in pigs of different ages and sexes in Southeast District, Botswana
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute., 2000) Nsoso, S.J.; Mosala, K.P.; Ndebele, R.T.; Ramabu, S.S.; Verwoerd, Daniel Wynand
Botswana imports most pig-based products from neighbouring countries. Pig farming is limited by, among other things, the negative effect of parasites and diseases on production. The object of this study was to determine the prevalence of ecto- and endoparasites in pigs of different ages and sexes in the Southeast District of Botswana. Thirty-nine pigs were sampled for endoparasites and 19 for ectoparasites during a period of 2 1/2 months. Of all the pigs sampled, 54,55% were infected with Ascaris suum, 20,45 % with Trichostrongylus spp. and 6,82 % with Trichuris suis. Ascaris suum was found to be the most common endoparasite infesting both mature, i.e. 12 months and older, and young, i.e. less than 12 months old, pigs. Although not significantly different (P > 0,05), the prevalence of this parasite species was slightly higher (68,42 % with an average of 1 023 ± 545 eggs per gram (EPG) of faeces per pig) in mature than in young pigs (55 % with an average of 1 500 ± 846 EPG of faeces per pig). The prevalence of Trichostrongylus spp. was lower in mature (5,26% with 20 ± 14 EPG of faeces per pig) than in young pigs (25 % with 22 ± 9 EPG of faeces per pig). The prevalence of T. suis was also lower in mature (0 % infection) than in young pigs (15 % with 9 ± 4 EPG of faeces per pig). The prevalence of the three endoparasite species was not significantly different between the sexes A. suum (1 020 ± 883 v. 1 503 ± 522 EPG of faeces per pig), Trichostrongylus spp. (24 ± 14 v. 18 ± 8 EPG of faeces per pig) and T. suis (11 ± 6 v. 2 ± 4 EPG of faeces per pig) for male and female pigs respectively. Sarcoptes scabiei was the only ectoparasite identified on the pigs sampled for external parasites. It infested 40 % of all pigs but the infestation on young pigs (70 %) was higher than on the mature ones (33,33 %). Since the infection of internal and external parasites was similar in young and old pigs of both sexes, controlling parasites is of great importance since these generally lead to reduced production and are also of public health concern . It is recommended that a further study be carried out to investigate the effect of internal and external parasites on productivity.
The influence of Mannheimia haemolytica A1 seed culture inoculum cell density on the production of leukotoxin in submerged culture supernatant
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Odendaal, M.W.; Verwoerd, Daniel Wynand; Du Plessis, Lizette
Mannheimia haemolytica leukotoxin is produced during the logarithmic growth phase in submerged culture in RPMI 1640 medium with and without the addition of foetal calf serum or albumin . In order to establish a pattern of optimal leukotoxin production in small volumes in submerged cultures and to define some parameters involved, two high leukotoxin producing Mannheimia haemolytica strains were grown in RPMI 1640 medium containing either FCS or BSA. The cell growth and leukotoxin production abilities of each strain were determined concomitantly every hour in RPMI 1640 medium containing each of the additives over a time period of 6 h. The growth performance of three dilutions of a standardized seed culture inoculum prepared with each of the cultures and additives were simultaneously compared with each other using the above parameters. The different seed culture inoculum dilutions had a definite effect on the time and quantity of leukotoxin production. Both strains demonstrated peak leukotoxin production after 4 h of active growth. The addition of albumin to both isolates gave slightly increased leukotoxin levels, and both showed that the peak leukotoxin was not associated with peak cell concentration . Obvious quantitative differences in the ability of different M. haemolytica strains to produce leukotoxin were noted. Strain 12296 produced optimal leukotoxin concentration from the medium (1/25) dilution of the seed culture inoculum after 4 h, whereas strain 1/10 produced the same concentration with the low (1/5) dilution seed culture inoculum, possibly reflecting the superior production ability of the first strain. However, each strain of M. haemolytica appeared to have its own specific logarithmic cell growth and leukotoxin production pattern. The peak cell density of M. haemolytica grown in submerged RPMI 1640 culture medium cannot be used as an indication of optimal leukotoxin levels.
Aerobic intestinal flora of wild-caught African dwarf crocodiles Osteolaemus tetraspis
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Henton, Marijke M.; Riley, J.; Agnagna, M.; Verwoerd, Daniel Wynand; Huchzermeyer, Fritz W.
Intestinal contents were collected from wild-caught African dwarf crocodiles (Osteolaemus tetraspis) in 1993 and 1995 which were slaughtered at urban markets in the Congo Republic. The samples were kept frozen and brought back to Onderstepoort for aerobic culture. Out of 29 specimens, 33 species of bacteria and 20 species of fungi were isolated. The bacteria included three isolates of Salmonella and eight isolates of Escherichia coli, most of the latter being rough strains. The flora of individual specimens contained 1-5 bacterial and 0-5 fungal species. Neither Aeromonas hydrophila nor Edwardsiella tarda were isolated from any of the samples.
Ultrastructural study of the luminal surface of the ducts of the epididymis of gallinaceous birds
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute ., 2000) Josling, D.; Verwoerd, Daniel Wynand; Aire, Tom A.
The various ducts of the epididymides of four gallinaceous birds, the turkey (Meleagris gallopavo) , domestic fowl (Gallus gallus), guinea-fowl (Numida meleagris) and Japanese quail (Coturnix coturnix japonica) were studied at the scanning and transmission electron microscopy levels. The tissues were fixed either by immersion or vascular perfusion, for comparative purposes. Each duct system, save for a few details, presented similar morphological features in all species. The epithelial surface of the rete testis was regular and each cell bore a single cilium, as well as numerous, or in some parts, very few, short, regular microvilli. Each of the Types I and II non-ciliated cells of the proximal and efferent ducts displayed abundant, moderately long and regular microvilli, and a solitary cilium. The ciliated cells exhibited tufts of cilia. The Type III non-ciliated cell of the connecting and epididymal ducts exhibited a solitary cilium, and numerous microvilli which were intermediate in length between those of the rete testis and those of the efferent ducts. Vascular perfusion of the avian epididymal tissue was the superior method of fixation because it minimised the developments of fixation artefacts. Apocrine secretion did not appear to occur in the epididymis of these birds as the apical blebs of Types I, II and III cells, which have previously been reported, only manifest in this study in inadequately fixed tissues, and were therefore viewed as being artefacts. The present findings suggest that the current terminology, as applied to the avian epididymis, be retained.

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