African Journals Online
Journal of the South African Veterinary Association

Volume 74 Number 2, June 2003
Abstracts

A comparison of selected public health criteria in milk from milk-shops and from a national distributor

More O'Ferrall-Berndt M.

Abstract: Selected public health criteria of pasteurised milk available to the consumer from milk-shops in a pre-defined area of Pretoria compared with a national distributor's milk was evaluated. Of the 135 milk samples purchased from milk-shops, 87 % were not fit for human consumption on the basis of the minimum standards prescribed in the Foodstuffs, Cosmetics and Disinfectants Act, 1972 (Act 54 of1972). The national distributor's milk (n = 79) did not contain any pathogens, toxins nor inhibitory substances and passed all the criteria laid down in the Act. Even though milk-shop milk was sold as having been pasteurised, 38.5% of samples were alkaline phosphatase positive, indicating probable inadequate pasteurisation. Milk-shop milk quality varied between milk-shops and between sampling days and differed significantly (P Escherichia coli was detected in 1 ml of 17% of milk-shop milk, 95% of which originated from milk which was alkaline phosphatase positive. Salmonella spp. could not be detected in 1 ml in any of the E. coli-positive milk tested. Staphylococcus aureus was isolated from 40% of milk-shop milk samples, and S. aureus enterotoxins from 7.8 % of 51 cultures. Inhibitory substances were detected in 54.1 % of milk-shop milk. The presence of inhibitory substances and the isolation of E. coli and S. aureus (some of which were able to produce enterotoxins) indicated potentially unsafe milk and poses a serious public health risk to consumers.

Keywords: Milk hygiene, Milk-shops, National distributor, Pathogens, Pretoria, Toxins, Veterinary public health

Comparison of 3 tests to detect acaricide resistance in Boophilus decoloratus on dairy farms in the Eastern Cape Province, South Africa

Mekonnen, S.; Bryson, N.R.; Fourie, L.J.; Peter, R.J.; Spickett, A.M.; Taylor, R.J.; Strydom, T.; Kemp, D.H.; Horak, I.G.

Abstract: The susceptibility of the larval offspring of engorged female Boophilus decoloratus, and of the engorged females, collected from cattle on the dairy farms Brycedale, Sunny Grove and Welgevind in the Eastern Cape Province, South Africa, was tested against the acaricides amitraz, chlorfenvinphos and cypermethrin. Resistance was determined by means of the Shaw Larval Immersion Test (SLIT) for larvae and the Reproductive Estimate Test (RET) and Egg Laying Test (ELT) for adults. At Brycedale the tests all indicated resistance to chlorfenvinphos, and RET and ELT indicated resistance to amitraz and emerging resistance to cypermethrin. At Sunny Grove, B. decoloratus was resistant to cypermethrin using SLIT and exhibited emerging resistance to chlorfenvinphos with SLIT and to cypermethrin with both RET and ELT. At Welgevind, resistance was recorded against chlorfenvinphos (SLIT) and against cypermethrin (ELT), and emerging resistance against permethrin (RET). The results obtained with RET and ELT were generally comparable, but often differed from those obtained with SLIT. Resistance could be detected within 7 days with ELT compared to 42 days with RET and 60 days with SLIT.

Keywords: Acaricide resistance tests, Boophilus decoloratus, Dairy cattle, South Africa

Parasitic helminths of veterinary importance in cattle, sheep and goats on communal farms in the northeastern Free State, South Africa

Tsotetsi, A.M.; Mbati, P.A.

Abstract: The purpose of the study was to record and determine intensities, seasonal incidence and distribution of helminth parasites of veterinary importance that occur in cattle, sheep and goats in the northeastern Free State. The study was conducted at Harrismith and Kestell and in Qwa-Qwa from March 2000 to May 2001. Cattle of various breeds (including Bonsmara, Simmentaler and Friesian), Merino sheep and Angora goats were sampled. Faecal samples were analysed using the McMaster and Visser sieve techniques for egg counts and faecal cultures for 3rd-stage nematode larvae identification. Haemonchus and Oesophagostomum were the dominant nematode genera found to be infecting the animals. The socioeconomic status of the farmers in the study area was determined through a questionnaire survey aimed at recording their management strategies. It indicated that 81 % of farmers take care of their livestock by feeding them with supplements. The low to moderate faecal egg counts from cattle showed that helminth infections in this region are still under control even though helminthosis seems to be a problem in small-stock, since EPG counts of more than >1000 were found. Cattle farmers in this region are encouraged to continue with good animal husbandry practices that have ensured that helminth infections rates are kept low. Small-stock farmers are, however, encouraged to control helminth infections in their sheep and goats by anthelmintic treatment.

Keywords: Faecal egg counts, Helminths, Livestock

Effect of feeding urea-molasses blocks with incorporated fenbendazole on grazing dairy heifers naturally infected with gastrointestinal nematodes

Waruiru, R.M.; Onyando, C.O.; Machuka, R.O.

Abstract: Between June 1999 and August 2000, the effects of feeding medicated urea-molasses supplement blocks on the growth of dairy heifers in a marginal area of central Kenya were assessed by comparing the live-weight gain of supplemented and unsupplemented heifers grazing the same pasture. Thirty-nine heifers with an average age of 9.6 months were initially treated orally with albendazole (10 mg / kg body weight) and assigned to 3 groups: group I was fed urea-molasses blocks with incorporated fenbendazole (MUMB), group II was fed urea-molasses blocks (UMB) and group III heifers (control) received no block supplementation (NBS). Body weights of the heifers and faecal egg counts (FECs) were measured monthly and larval cultures were made of positive faecal samples of each group. The mean cumulative live-weight responses of the MUMB and UMB groups were significantly greater than the NBS group (P < 0.05). However, at the end of the experimental period, the mean weight gain of the MUMB group did not differ from that of the UMB group (P >0.05). The FECs were moderate to low in all groups and decreased progressively with increasing age of the animals; FECs for the urea-molasses-supplemented groups remained significantly lower than those of the NBS group throughout the experimental period (P Haemonchus and Trichostrongylus were the predominant nematode genera found in the heifers, but Cooperia, Bunostomum and Oesophagostomum were also present. These results indicate that feeding of urea-molasses blocks substantially reduced production losses attributable to nematode infection of young grazing cattle, and confirms previous observations that well-fed animals are better able to overcome the effects of helminth infections.

Keywords: Cattle, Fenbendazole, Gastrointestinal parasitism, Kenya, Urea-molasses blocks

Anthelmintic treatment in horses: the extra-label use of products and the danger of under-dosing

Matthee, S.

Abstract: Anthelmintic products form the basis of helminth control practices on horse stud farms at present. Regular evaluation of the efficacy of these products is advisable, as it will provide information on the worm egg reappearance period and the resistance status in the worm population. The aim of this study was to evaluate the efficacy of doramectin, pyrantel pamoate, ivermectin and moxidectin on a Thoroughbred stud farm in the Western Cape Province, South Africa. The study also compared the anthelmintic efficacy of two moxidectin formulations administered at their recommended dosages (an injectable, at 0.2 mg / kg, not registered for horses, and an oral gel at 0.4 mg / kg, registered for horses). Two mixed-sex groups of 30 yearlings and 40 weaners were tested in 2001 and 2002, respectively, divided into 3 and 4 groups of equal size. In 2001, moxidectin was one of 3 drugs administered orally and at a dose rate of 0.4 mg / kg. In 2002, pyrantel pamoate and ivermectin were orally administered at 19 and 0.2 mg / kg. Moxidectin and doramectin (the latter not registered for horses) were administered by intramuscular injection at a dose of 0.2 mg / kg, the dosage registered for other host species. The faecal egg count reduction test was used to determine the anthelmintic efficacies in both years. Each animal acted as its own control and the arithmetic mean faecal egg count and lower 95 % confidence limit was calculated for each of the groups. A 100 % reduction in the faecal egg counts and a 100 % lower 95 % confidence limit was recorded for moxidectin (0.4 mg / kg) in 2001. In 2002, a 99 % and 96% reduction was recorded for pyrantel pamoate and ivermectin, respectively. In the same year doramectin and moxidectin (both injectable and given at 0.2 mg / kg) did not have any effect on worm egg counts. Of the 4 drugs tested in 2002, only pyrantel pamoate recorded lower 95 % confidence limits above 90 %.

Keywords: Anthelmintic treatment, Equus caballus, Faecal egg count reduction, Underdosing

Infestation with the sheep body louse (Bovicola ovis) in Merino lines divergently selected for maternal multiple rearing ability: short communication

Cloete, S.W.P.; Laubscher, J.M.; Cloete, J.J.E.

Abstract: Data were obtained from a population consisting of 160 Merino ewes, as well as 64 male and 75 female progeny of these ewes at the 2-tooth age. The age and sex groups were maintained in separate flocks. The population has been divergently selected from the same base since 1986, either for (high or H line) or against (low or L line) maternal multiple rearing ability. All animals were inspected for sheep lice (Bovicola ovis) during September / October 2002 after a wool growth period of at least 4 months. When expressed relative to mean L-line performance, the advantage in lambs weaned per ewe during the lambing season amounted to approximately 110 % in the H line (1.01 vs 0.48; P < 0.01). The proportion of animals on which 1 or more lice were observed were markedly lower in 2-tooth replacement ewes than in replacement rams and mature breeding ewes (0.053 vs 0.625 and 0.531, respectively; P < 0.01). One or more lice were observed on a lower proportion of H-line ewes than on those of the L line (0.413 vs 0.571, respectively; P < 0.10), while a similar tendency was observed in 2-tooth ewe hoggets (0.033 vs 0.143, respectively; P =0.16). When the mean number of lice on individuals on which 1 or more lice were observed was compared between lines, the average number of lice observed on H-line young rams was lower than in the L line (4.36 ± 0.85 vs 9.71 ± 1.84 lice, respectively; P < 0.01). A similar tendency was observed in mature breeding ewes (2.15 ± 0.38 vs 3.22 ± 0.42 lice, respectively; P < 0.20). The more highly reproductive H-line ewes were not more susceptible to infestation with B. ovis than ewes of the L line. In fact, available evidence suggest that H-line animals could be more tolerant of B. ovis than those of the L line.

Keywords: Integrated control, Lice management, Reproduction, Resistance, Susceptibility