CONSERVATION ECOLOGY BASED ON PARASITE-NUTRIENT-SEASONAL INTERACTIONS IN NILGIRI TAHR (Nilgiritragus hylocrius)
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Date
2017-12-30
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR
Abstract
The study was conducted to evolve suitable strategies for the conservation of the
endangered Nilgiri tahr (Nilgiritragus hylocrius Ogilby, 1838) by investigating the primary
interaction of the species with its parasites, forages and the season. The three habitats of
Eravikulam, Nelliampathi and Kochupamba were selected and the study was conducted in the
three seasons of summer, monsoon and post-monsoon. The indicators selected were incidence
of parasitism, the degree of parasitic infection, the nutrient composition of forage, health status
of the herd, stress level of animals, habitat features, herd structure and the general behavior of
the herd. The indices in this regard were examined and recorded across the seasons. The herd size recorded ranged from 12 in Kochupamba to 36 in Eravikulam with adult
females comprising nearly half of the herd. The habitats were typically of grass lands with short
grasses adjacent to rocky cliffs. The activity budget was recorded to assess the behavior of the
animals and it revealed grazing (37.4%) and resting (23.3%) as the prominent activity in tahr
with very low share of browsing (0.8%) in the species. The activity budget also observed minor
shifts between seasons, habitats and in age-sex class. The predominant grass species in each
habitat were identified and the nutrient composition of the grasses was analysed showing
significant difference between seasons in dry matter, crude protein, crude fibre, ether extract,
total ash and nitrogen free extract. The body condition score (BCS) of all the animals ranged
from three to five indicating the herds to be healthy across all seasons. There were no reports of
disease or mortality in the animals in the study period. A total parasitic incidence of 38.9 per cent was observed and the degree of infection
was assessed to be mild as indicated by the eggs per gram (EPG) below 1000 in the observed
data. Strongyles and coccidia were the major parasites with 34.3 per cent and 15.5 per cent
incidence respectively and the other parasites recorded were Moniezia, Trichuris, Capillaria,
and Strongyloides. There was significant difference in parasitic incidence between habitats and
seasons, with higher share in monsoon (58.9%) followed by summer (40%) and post-monsoon
(17.8%). Eggs per gram also observed significant seasonal difference with higher count in
monsoon (360.64) followed by post-monsoon (232.81) and summer (114.29). The faecal
cortisol metabolite level estimated by enzyme immunoassay was significantly different
between habitats, with Eravikulam recording a higher mean value of 472.17 ng/g, and the
difference was non-significant between seasons. Significantly higher faecal cortisol metabolite
was observed in parasite infected animals compared to non-infected animals.
The study identified the significant presence of parasites in tahr population, indicating
the dynamism and balance in equilibrium of host-parasite relationship which is a major driver
in the organization of the ecosystem. The energy flow dynamics across seasons and habitats
significantly influence the interrelationship of the host and parasite.
Description
Submitted in partial fulfilment of the requirement for the degree of
Doctor of Philosophy in LIVESTOCK PRODUCTION MANAGEMENT.