Evaluation of water needs for modern commercial broiler farms and model development to estimate on-farm water needs

Abstract

With global populations expected to rise, appropriation of clean water supplies for human consumption pose capacity challenges for agricultural sectors. Broiler (meat-type) chicken production consumes large amounts of water and ensuring water needs are met during a flock are crucial, particularly for farms raising large broilers in hot weather. Water needs have been commonly overlooked in the industry resulting in references to the quantity of water growers need to supply during production should be “adequate”, “sufficient”, or “plenty”. In recent years there has been increased interest by broiler industry stakeholders to better understand water consumption needs for farms. Past consumption estimates do not reflect current broiler genetic strains or housing systems therefore three studies were conducted to 1) estimate broiler drinking water consumption (BWC) needs and water-feed-ratio (WFR) for broilers grown to 63 days raised under commercially relevant conditions for three seasonal periods; winter, summer, and spring 2) develop a water consumption model to estimate BWC and evaporative cooling system water consumption (EWC) based on a farm’s characteristics and geographic location 3) estimate annual total water consumption (TWC) needs for 14 locations across the U.S. broiler belt based on 27 farm configurations. Pen trials were conducted in a tunnel ventilated research house at the USDA Poultry Research Unit in Starkville, MS to establish BWC and WFR values for broilers finished at 63 days in study 1. Due to interruptions by the COVID-19 pandemic, only winter and summer flocks have been completed. Both flocks were raised under commercially relevant conditions following current environmental management recommendations and flock husbandry practices. Results suggest broilers grown during winter consumed 15,714 L per 1,000 birds during the 63 day growth period. Mean flock WFR was 1.82 kg water per kg feed, lower than the industry rule of thumb WFR of 2 kg water per kg feed. Summer flock consumption was 13,619 L per 1,000 birds however results were not typical likely due to a chick quality issue and high mortality. A model was developed in MATLAB for study 2 to estimate the two main water consumption usages on a broiler farm; broiler drinking water consumption (BWC) and evaporative cooling system water consumption (EWC). Governing equations were developed to estimate daily BWC and EWC values to determine an annual total water consumption (TWC) given farm inputs (e.g. house size, geographic location, broiler growth period). Estimates for BWC were based on WFR results from study 1 and primary breeder feed consumption data. Estimates for EWC were determined by calculating peak evaporative cooling (EC) system evaporation rates using outside weather conditions and psychrometric equations. EC operation boundary conditions were incorporated into the model to mimic farm EC operation. Model estimates were made for a farm in east Alabama growing a 63 day old broiler in a 13.1 x 155.5 m house. Actual farm BWC and EWC were compared to model outputs to determine the ability of the model to estimate farm water consumption. Model estimates for daily BWC overestimated consumption by 7% compared to actual farm data. Estimates for EWC were considerably higher compared to actual farm data, overestimating consumption by 140%. It should be noted the model estimates peak EWC and assumed model EC operating condition may have differed to actual EC operating. The model correctly predicted farm EC operation for 77% of the observed events over the study period. In study 3, the model was used to estimate mean TWC for 14 locations representing high concentrations of U.S. domestic broiler production over a 30-yr period. Consumption estimates were made for a set of 27 farm configurations based on broiler age, house size, and house wind speed. The range of annual TWC for the 14 locations was approximately 1.22 to 5.73 million L per house. Variability in TWC between location was driven by EWC estimates based on local weather conditions. As discussions within the industry become more frequent regarding farm water demand, there is a need for relevant water consumption data for today’s commercial broiler farms. Both industry and the research community should update and maintain water consumption needs to provide growers and industry stake holders a better understanding of water demands.