THE PERIPARTURIENT INCREASE IN TRICHOSTRONGYLE EGG COUNTS IN YANKASA EWES IN ZARIA, NORTHERN GUINEA SAVANNAH ZONE OF NIGERIA

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dc.contributor.authorNGOZI, PAULINE CHIEZEY
dc.date.accessioned2014-11-06T07:39:19Z
dc.date.available2014-11-06T07:39:19Z
dc.date.issued1998-11
dc.descriptionTHESIS SUBMITTED TO THE POST GRADUATE SCHOOL AHMADU BELLO UNIVERSITY, IN PARTIAL FULFILMENT FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF PARASITOLOGY/ENTOMOLOGY FACULTY OF VETERINARY MEDICINE, AHMADU BELLO UNIVERSITY, ZARIA - NIGERIA. NOVEMBER, 1998en_US
dc.description.abstractStudies were carried out in Zaria to investigate the occurrence of a pcriparturient increase in Trichostrongyle egg counts in naturally infected Yankasa ewes lambing at various times of the year, using serial egg counts. The first study using ewes in the last month of gestation and non-pregnant ewes as controls, showed that a significantly ( P < 0.05) greater increase in egg counts occurred in the lambing ewes during the periparturient period when compared with the non-pregnant ewes sampled within the same period. A second study using ewes in their last month of gestation, grazing a separate pasture, confirmed the occurrence of a periparturient increase in egg counts in lambing ewes. Packed Cell Volume declined with increased egg counts but Total protein values did not show an appreciable change. In individual ewes, the periparturient rise in egg counts started about four weeks before parturition with a peak within the first four weeks of parturition/lactation. Larval culture showed that Haemonchus contortus was the main contributor to the rise. Another experiment designed to evaluate egg counts in pregnant animals as well as evaluate the lambing performance of naturally infected ewes was carried out in a flock of 63 ewes which continuously ran with rams. Susceptibility of ewes at pregnancy was assessed by faecal helminth egg counts in ewes which were pregnant at periods of different pasture larval availability. Ewes lambing in October which had been pregnant in the months of June through September, months of high larval availability did not show significant differences (P > 0.05) in egg counts in early and mid pregnancy but there was a significant increase in egg counts in late pregnancy and this started about the 19th week of gestation. Similarly, ewes lambing in June which had gone through pregnancy through the months of February to May when there was only a low level of larvae available on pasture did not show a significant difference in egg count between early and mid pregnancy but showed a significant increase in late pregnancy and this started about the 17th week of gestation. Ewes that lambed in June had significantly higher egg counts in late pregnancy than ewes lambing in October. Ewes that lambed in the early dry season had significantly higher egg counts (P < 0.05) during the pre-lambing period than ewes lambing in the early wet or late wet seasons. There were no significant differences in the Packed cell volume (PCV) concentrations of ewes lambing in the different seasons but ewes that lambed in the late dry seasons had consistently lower PCV concentrations. Lambs born in the early dry season had picked up low level helminth infections which were below 500 egg through the dry season months. In the rainy season the highest mean egg count in the lambs was 3,016 ± 1015 In contrast, lambs born in the early wet season became infected as early as seven weeks of age , showing egg counts of up to 10,000 egg, and high mortalities. Growth rate of lambs were however poor as they weighed an average of 19.2 ± 0.5 kg at 10 months of age. Analysis of the overall lambing performance showed that mean birth weight of lambs was 2.7 kg, fecundity was 1.1 lambs, and there were significantly (P < 0.05) less lambs born in the late wet season, lambing percentages being 9.5%, 23.3%, 25.9% and 38% for late wet, late dry, early wet and early dry season lambings respectively. 17.4% of ewes had lambing intervals (L I ) of 193 days and another 34.8% had LI of 220 days. the remaining 47.8% had Lambing intervals greater than 220 days. Low mean egg counts (5025 ± 4441epg) were associated with long lambing intervals, and lambing intervals over 220 days were assoeiated with mean egg counts of 16,317 ± 2315 egg. Ewes with high egg counts ending pregnancy in low body condition neglected their lambs which subsequently died of hyponutrition. Progesterone profiles of the ewes evaluated by radioimmunoassay showed that long lambing intervals were due to delayed resumption of ovarian activity post partum. In a study to show the effect of weaning on the occurrence of the periparturient rise in egg counts, three groups of 10 ewes each had their lambs weaned at week 0, week 1 and week 4 of lambing respectively. Weaning did not seem to have a significant effect on the occurrence of the periparturient rise in egg counts unless the lambs were separated from the dams immediately after birth (weaned week 0). Treatment of ewes with levamisole hydrochloride at one week after lambing (OWAL), one week before lambing (OWBL), two weeks before lambing (TWBL) and week of lambing (WOL), showed that treatment immediately after lambing or not later than one week of lambing significantly eliminated the occurrence of the periparturient rise in egg counts. This study is the first to comprehensively demonstrate the occurrence of a periparturient rise in helminth egg output occurs in Yankasa ewes. The study also demonstrated that the increase in egg output arises from the development of inhibited populations of larvae in the ewes as well as from newly acquired infections. Larvae derived from the periparturient rise in faecal egg count was shown to be the major source of gastrointestinal nematode infection for young lambs. Taken together, this study also indicates that helminlhosis while not directly interfering with reproduction, may decrease reproductive efficiency in the ewe by depreciating its body condition. The increase in helminth egg output at the periparturient period indicates that time of parturition can influence the general level of parasitism within a flock due to the breakdown in ewe defence mechanisms as a result of endocrine events associated with late pregnancy and early lactation. Therefore in breeding flocks, measures must be taken to control helminth infections at this time to avoid a build up of larvae on pasture and the subsequent morbidity and production losses associated with parasitismen_US
dc.identifier.urihttp://hdl.handle.net/123456789/5566
dc.language.isoenen_US
dc.subjectPERIPARTURIENT,en_US
dc.subjectINCREASE,en_US
dc.subjectTRICHOSTRONGYLE,en_US
dc.subjectYANKASA EWES,en_US
dc.subjectSAVANNAH ZONE OF NIGERIAen_US
dc.titleTHE PERIPARTURIENT INCREASE IN TRICHOSTRONGYLE EGG COUNTS IN YANKASA EWES IN ZARIA, NORTHERN GUINEA SAVANNAH ZONE OF NIGERIAen_US
dc.typeThesisen_US
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