WEATHER INFLUENCE OF STOCKING DENSITIES ON THE PERFORMANCE OF BROILER CHICKENS

Abstract

This study was conducted to investigate the impact of weather on stocking densities and the performance of broiler chickens; with a view of establishing optimum stocking density for raising broiler chickens during the wet season in Southwestern Nigeria. Ninety (90) day-old chicks of Arbor acre breed were used as experimental units in the experimental trial that lasted eight (8) weeks. The birds were randomly assigned to three treatments of stocking densities (5, 10, 15 birds/m2) with three replicates per treatments. The birds were raised in deep litter system bedded with wood-shaving litter at 1 m2 per replicate. The meteorological data (Temperature and Relative humidity) within and outside the pen were obtained using the Maxims thermocron i-button Temperature and Humidity sensors, which were programmed to measure at 10 minutes sampling interval. Data collected were on daily ambient temperature, humidity, feed intake, water intake, weight gain, computed feed conversion ratio, haematological analysis and carcass parameters. From this study temperature of the broiler pens is inversely related to its relative humidity across the treatments with relative fluctuations as the birds grow; due to weather modification influence of stocking densities within the pens. At the end of the eighth week the temperature within the pens (ambient temperature) increased with the stocking densities; stocking density 15 birds/m2 being the hottest while 5 birds/m2 was the least hot. The highest value change in weight gain was observed between weeks 6-7 among the treatments. Observations showed that birds at stocking density of 5birds/m2 performed better in terms of growth and followed by those of 10 birds/m2. Stocking densities of 15birds/m2 recorded the lowest weight gain. Furthermore, the temperature within the pens and the general weather conditions in and outside the poultry house are observed to contribute significantly to the changes in feed intake and water consumption in all the treatments. However, the core of all the performance indices occurred between weeks 6-8 at mean temperature range of 25.5-28oC and RH between 86-90% in all the treatments. Although the combine influence of weather and performance on the growth of the birds diminishes as the stocking density increases. The relative dynamics of temperature and relative humidity favoured higher increase of monocyte and neutrophil in treatments 5 birds/m2 and 15 birds/m2 than in treatment 10 birds/m2; hence, treatments 5 birds/m2 and 15 birds/m2 seem to be more susceptible to chronic inflammatory disease and acute stress than those in treatment 10 birds/m2. Also, lymphocyte of the birds was found to increase as the mean temperature increased and relative humidity decreased in all the treatments; meaning that every of the treatments has tendency of being susceptible to chronic infection as predicted by the weather. The weather modification within the pens by the various stocking densities influenced organ and carcass growth of the birds across the treatments. This study suggested that broiler chickens could be reared between 6 and 8 weeks without compromising their optimum performance under any of these stocking densities and similar weather situation of this study; however where land is adequate, better welfare under 5birds/m2 will be realized. In addition, fatality of weather modification could be prevented by the provision of good ventilation. Further studies conducted during dry season that will enable comparison of broiler chickens performance is suggested to balance the outcome of this study that falls within the wet season in Nigeria.