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McMaster technique and pooled larval cultures
Nematode egg counts were recorded bimonthly at the same time of day (7:00 – 9:00) from each animal. As a result of a daily natural variation in the FEC that bas been recorded in horses (Warnick, 1992) two readings per month were preferred to one to ensure a more precise representation of the egg counts of each animal during the study period. Faecal samples were collected directly from each animal’s rectum and were processed the same day as their prolonged storage (> 1 week) might have lead to artificially low egg counts due to hatching of the eggs (Herd, 1992b). The McMaster technique of Reinecke (1983) was followed using a modification (Krecek, personal communication, 1997). The use of a blender or ball bearings was not required because the faeces were fresh and moist and thus only a wood spatula was required to make a suspension of them in the sugar solution as descnbed by Reinecke (1983). Four grams of faecal material was weighed off: broken up and mixed in with 56 mL of a sahrrated sugar solution. The mixture was thoroughly mixed using a wooden spatula. While continuously stirring, an amount of the mixture was transferred to the three counting chambers of the »Eggs-Acto » McMaster slide (Focal Point, South Africa) by means of a wide-mouthed pipette. All three counting chambers were filled and the slide allowed to stand for approximately two to five minutes. This resting period allowed the eggs to rise to the surface, which :facilitated examination and counting of the eggs. All the eggs were counted and identified in all three chambers of the McMaster slide. The FEC were expressed as the eggs per gram (epg) offaeces which was calculated using the following equation: epg = egg count in chamberslnwnber ofchambers counted x 100 Faecal cultures are used to detennine the larval species composition as well as to differentiation between the large and the small strongyles. This method is based on optimum conditions such as high temperature (28°C) and high humidity that are both important for the hatching of the eggs and development of larvae into L3. These conditions were obtained in a room where temperature and humidity were controlled. The pooled fuecal samples comprising of equal amounts, based on weight, of fresh :faeces from each of the donkeys in each camp were obtained twice a month for the making of pooled larval cultures following the method by Reinecke (1983).
The :faeces were broken up and mixed with an equal volwne of fragmented vermiculite and a small amount of water. The mixture was placed in a one-litre wide-mouth glass jar (9 cm diameter) and tamped down with a tlat-bottomed stick while another stick was held in the centre of the jar to produce a hole in the mixture, which reached to the bottom of the jar. The inner surface of the jar was washed down and a screw cap placed on the jar. The cultures were incubated in a hwnidified room at 28 °C for a period of eight to ten days. One hundred L3 from each glass jar were harvested and identified using the guideline of BUrger and Stoye (1968). The larval species and genera identified from each sample were expressed as a percentage ofthe total count ofall L3.
Adhesive tape swab technique for detecting Oxyuris equi eggs
The female pinworm, 0. equi, protrudes from the anus of an equid and deposits her eggs on the skin around the anus. Oxyuris eggs in horses are commonly detected by means of an adhesive tape swab tecluUque as they are rarely observed in :faecal examinations using methods such as the McMaster technique (Drudge and Lyons, 1989). In contrast, in a recent study on donkeys tmdertaken by Wells et al. (1998) these eggs were regularly recorded in their fueces by use of the McMaster teclmique. In the present study, faecal samples were examined from all the donkeys for the presence of Oxyuris eggs twice a month by means of the McMaster teclmique. In addition, however, it was decided to include the adhesive tape swab technique (Deplazes and Eckert, 1988) in the study to determine if the infection pattern of this helminth parasite in donkeys differs from that in horses.
The adhesive tape was placed in a loop arotmd one end of a microscope slide, with the adhesive side out. The tail of the donkey was elevated and the elbow of the left arm of the person taking the sample was pushed against its buttock. At the same time, the thumb of the right hand was used to finnly press the adhesive tape to the animal’s anal skin fold. The adhesive tape was then attached onto a pre-marked microscope slide, which was examined microscopically for the presence ofpinworm eggs (DepIazes and Eckert, 1988; Krecek, personal communication, 1997).
CHAPTER 1 GENERAl, INTRODUCTION
CHAPTER 2 LITERATURE REVIEW
1. The role and management ofdonkeys in South Africa
2. Helminth parasites ofdonkeys
3. The effect of helminth parasitism on donkeys
4. Methods to detect helminth parasites
5. Helminth control methods for donkeys in Africa
CHAPTER 3 METHODS USED IN » THE STUDY
1. Weekly exercise
2. Live weights
3. McMaster technique and pooled larval cultures
4. Adhesive tape swab technique for detecting Oxyuris equi eggs
5. Faecal egg count reduction test
6. Standard haematology analysis of blood samples collected from the donkeys
7. Filtering of blood samples and staining to detect Setaria equina
8. Body condition score ofthe donkeys
9. Body measurements ofthe donkeys
10. Collection of herbage samples
11. Processing ofherbage samples
12. Isolation ofparasitic L3 from suspended soil and extraneous material
13. Verification ofthe efficacy ofthe combination ofmachine washing and centrifugation technique used to determine parasitic nematode larvae in herbage samples
14. Pasture infectivity as a function ofthe faecal egg counts and the amount offaecal material produced
15. Grazing consumed by the donkeys in each camp
16. Necropsy and mucosal larval recovery techniques
17. Processing of intestinal washings and ingesta for worm recovery and identification
CHAPTER 4 THE EFFECT OF ALTERNATIVE MANAGEMENT INTERVENTIONS ON THE LEVELS OF HELMINTHS IN LIVE DONKEYS AND ON PASTURE
1. Introduction
2. Materials and methods
3. Results
4. Discussion
CHAPTER 5 THE EFFECT OF THE THREE MANAGEMENT INTERVENTIONS ON THE HELMINTHS AND GASTEROPHILIIDS RECOVERED FROM THE DONKEYS AT NECROPSY
1. Introduction
2. Materials and Methods
3. Results
4. Discussion
CHAPTER 6 Cylicocyclus asinus sp. n. (NEMATODA: STRONGYLOIDAE: CYATHOSTOMINAE) FROM DONKEYS, Equus asinus, IN SOUTH AFRICA
1. Introduction
2. Materials and methods
3. Results
4. Discussion
GENERA.L CONCLUSION
SUMMARY
OPSOMMING
REFERENCES
