title: Impact of Feed Delivery Pattern on Aerial Particulate Matter and Behavior of Feedlot Cattle.
abstract: Fine particulate matter with less than 2.5 microns diameter (PM2.5) generated by cattle in feedlots is an environmental pollutant and a potential human and animal health issue. The objective of this study was to determine if a feeding schedule affects cattle behaviors that promote PM2.5in a commercial feedlot. The study used 2813 crossbred steers housed in 14 adjacent pens at a large-scale commercial West Texas feedlot. Treatments were conventional feeding at 0700, 1000, and 1200 (CON) or feeding at 0700, 1000, and 1830 (ALT), the latter feeding time coincided with dusk. A mobile behavior lab was used to quantify behaviors of steers that were associated with generation of PM2.5(e.g., fighting, mounting of peers, and increased locomotion). PM2.5samplers measured respirable particles with a mass median diameter ≤2.5 μm (PM2.5) every 15 min over a period of 7 d in April and May. Simultaneously, the ambient temperature, humidity, wind speed and direction, precipitation, air pressure, and solar radiation were measured with a weather station. Elevated downwind PM2.5concentrations were measured at dusk, when cattle that were fed according to the ALT vs. the CON feeding schedule, demonstrated less PM2.5-generating behaviors (p< 0.05). At dusk, steers on ALT vs. CON feeding schedules ate or were waiting to eat (standing in second row behind feeding cattle) at much greater rates (p< 0.05). Upwind PM2.5concentrations were similar between the treatments. Downwind PM2.5concentrations averaged over 24 h were lower from ALT compared with CON pens (0.072 vs. 0.115 mg/m³,p< 0.01). However, dry matter intake (DMI) was less (p< 0.05), and average daily gain (ADG) tended to be less (p< 0.1) in cattle that were fed according to the ALT vs. the CON feeding schedules, whereas feed efficiency (aka gain to feed, G:F) was not affected. Although ALT feeding may pose a challenge in feed delivery and labor scheduling, cattle exhibited fewer PM2.5-generating behaviors and reduced generation of PM2.5when feed delivery times matched the natural desires of cattle to eat in a crepuscular pattern.
authors.affiliation: Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX 79409, USA. fmmitloehner@ucdavis.edu.
authors.forename: Frank M
authors.initials: FM
authors.lastname: Mitloehner
authors.affiliation: Livestock Issues Research Unit, USDA-ARS, Lubbock, TX 79409, USA. jefftadailey@gmail.com.
authors.forename: Jeff W
authors.initials: JW
authors.lastname: Dailey
authors.affiliation: Livestock Issues Research Unit, USDA-ARS, Lubbock, TX 79409, USA. fmmitloehner@ucdavis.edu.|Julie Morrow passed away; however, she has played a critical role in the completion of this work.. fmmitloehner@ucdavis.edu.
authors.forename: Julie L
authors.initials: JL
authors.lastname: Morrow
authors.affiliation: Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX 79409, USA. john.mcglone@ttu.edu.
authors.forename: John J
authors.initials: JJ
authors.lastname: McGlone
keywords: behavior; feeding management; feedlot cattle; particulate matter