Abstract
BackgroundLayer chickens are exposed to high risks of production losses and mortality with impact on farm profitability. The harsh tropical climate and severe disease outbreaks, poor biosecurity, sub-minimal vaccination and treatment protocols, poor management practices, poor chick quality, feed-associated causes, and unintended accidents oftentimes aggravate mortality and negatively affect egg production. The objectives of this study were to estimate the probability of survival and evaluate risk factors for death under different intensive housing conditions in a tropical climate, and to assess the production performance in the housing systems.ResultsDaily mean mortality percentages and egg production figures were significantly lower and higher in the sealed pens and open houses (P < 0. 001) respectively. The total mean feed consumption/bird/day was similar for the open sided and sealed pens but the mean feed quantity per egg produce was significantly lower in the sealed pens ((P < 0.005). Seasons differently impacted on mortality with the hot-dry season producing significantly higher risk of mortality (61 times) and reduced egg production. Other parameters also differed except the egg production during the cold-dry season. Layers in sealed pens appear to have higher probability of survival and the Kaplan-Meir survival curves differed for each pen; ≥78 weeks old layer have higher probability of survival compared with the younger chickens and the 19–38 weeks age category are at highest risk of death (P < 0.001). The hazard-ratio for mortality of layers raised in sealed pens was 0.568 (56.8%).ConclusionReasons for spiked mortality in layer chickens may not always be associated with disease. Hot-dry climatic environment is associated with heat stress, waning immunity and inefficient feed usage and increase probability of death with reduced egg production; usage of environmentally controlled building in conditions where environmental temperature may rise significantly above 25°C will reduce this impact. Since younger birds (19–38 weeks) are at higher risk of death due to stress of coming into production, management changes and diseases, critical implementation of protocols that will reduce death at this precarious period becomes mandatory. Whether older chickens’ better protection from death is associated with many prophylactic and metaphylactic regimen of medications/vaccination will need further investigation.
Highlights
Layer chickens are exposed to high risks of production losses and mortality with impact on farm profitability
A negative association has been established between mortalities and net profits associated with lower egg productions [3,4], and a mortality of up to 4% during weeks 1–8, 15% during rearing (9–20 weeks) and 12% during the laying period (21- ≥72 weeks) has been established as standards for the industry in a tropical climate [5]
We evaluated the effect of open-sided and sealed intensive housing systems, ages of birds in lay and seasons on production performance and risk of death in layer chickens under a tropical environment
Summary
Layer chickens are exposed to high risks of production losses and mortality with impact on farm profitability. The harsh tropical climate and severe disease outbreaks, poor biosecurity, sub-minimal vaccination and treatment protocols, poor management practices, poor chick quality, feed-associated causes, and unintended accidents oftentimes aggravate mortality and negatively affect egg production. Other factors including severe disease outbreaks, poor biosecurity, sub-minimal vaccination and treatment protocols, poor management, practices, poor chick quality, feed-associated causes, and unintended errors and accidents influence production [1]. Laying hens are female chickens which are raised primarily for the purpose of commercial egg production These birds and the breeder flocks are at a higher risk of production losses, stress and pecking, higher disease incidents, inclement weather conditions and death due to long term exposures (≥72 weeks) to these factors on farms compared to meat type chicken [2]. Ghodasara and colleagues [6] have broadly classified mortality in layer hens into three viz those associated with brooding stage (26.23%), growing stage (24.56%), and laying period (49.21%)
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