Monitoring animal disease and productivity in Samoa : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Studies at Massey University
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Date
2008
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Massey University
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Abstract
This thesis presents two studies that form the basis of the Samoan Ministry of Agriculture
and Fisheries’ (MAF) recent efforts to enhance its animal disease surveillance capacity.
The first study investigated a method of enhancing the surveillance value of veterinary
case data collected by the MAF’s Animal Health Service, which provides the only
veterinary service for livestock in the country, through temporal analysis of cases and
syndromes by species. Threshold levels generated from 3-monthly moving averages combined
over 3 years of veterinary case data were used to identify unusually high numbers
of cases and the cause of these unusual events were investigated. Further, the analysis
of data in the system identified gaps in the coverage of the Animal Health Service which
helped identify alternative methods for conducting surveillance in these areas using the
Crops Division advisory officers.
The objective of the second study was to identify if the veterinary case data collected
by the Animal Health Service represented pig health problems in the general population.
Reproduction and mortality patterns were compared on a group of 10 holdings that were
regularly attended by the veterinary staff and 13 holdings that did not utilise the Animal
Health Service. The performance of these holdings, measured in liveborn piglets per sow
year and pre-weaning and post-weaning mortality were compared given their status as
client or non-client of the service and their exposure to various management factors like
confinement, protein supplementation, frequency of feeding, management time per sow
per day, the use of improved or exotic breeds, the extent of commercial activity and, in
the case of piglets their season of birth (rainy or dry season). The mean number of sows
per herd was 6, producing a mean litter size of 6.1 piglets with a mean interfarrowing
interval of 235 days. The median pre-weaning mortality per litter was 0 and a median
of 1 piglet per litter was used for productive purposes (consumed, gifted or sold) at a
median age of 153 days. It was found that the greatest influence on productivity in these
holdings was nutrition. Sow productivity (in terms of liveborn piglets per sow year and
pre-weaning survival) was best in the non-client, free range herds that did not provide
protein supplementation (but whose feeding was unrestricted due to their freedom to roam
and scavenge) and worst in client and non-client herds that were confined and not given
protein supplementation (due to restricted and underfeeding). The mortality of pigs postweaning
was significantly higher if they were free roaming, due to their loss to predation,
theft and being hit by car. The study showed that the health status of pigs was better on
holdings that did not use the Animal Health Service compared with those that did.
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Keywords
Pigs, Swine, Productivity, Samoan Ministry of Agriculture and Fisheries Animal Health Service, Diseases