Demographic features and mortality risks in smallholder poultry farms of the Mekong river delta region

Abstract

This study describes the demographic structure and dynamics of small scale poultry farms of the Mekong river delta region, one of the worlds highest-risk regions for avian influenza outbreaks. Fifty farms were monitored over a 20-month period, with farm sizes, species, age, arrival/departure of poultry, and farm management practices recorded monthly. The history of poultry flocks in the sampled farms was recovered using a flock-matching algorithm. Median flock population sizes were 16 for chickens (IQR: 10 - 40), 32 for ducks (IQR: 18 - 101) and 11 for Muscovy ducks (IQR: 7 - 18); farm size distributions for the three species were heavily right-skewed. There was substantial flock overlap on almost all farms, with only one farm practicing an all-in-all-out management system. The rate of interspecific contacts was high, with two out of three farms housing at least two bird species. Among poultry species, demographic dynamics varied. Muscovy ducks were kept for long periods, in small numbers and outdoors, while chickens and ducks were farmed in larger numbers, indoors or in pens, with more rapid flock turnover. Most chicks were sold young to be fattened on other farms, and broiler and layer ducks had a short production period and higher degree of specialization. The rate of mortality due to disease did not differ much among species, with birds being less likely to die from disease at older ages, but frequency of disease symptoms differed by species. Time series of disease-associated mortality and population size were correlated for Muscovy ducks (Kendalls coefficient {tau} = 0.49, p value < 0.01).\n\nImpacts O_LIThe structure and dynamics of poultry populations kept in small scale farms in the Mekong river delta were accurately described.\nC_LIO_LIPoultry farms mix poultry of different species, ages, and production types, with multiple overlapping flocks present on a farm at all times. This promotes the persistence of pathogens.\nC_LIO_LIThe three main farmed poultry species of poultry (chickens, ducks and Muscovy ducks) are managed differently and have different demographic characteristics.\nC_LI