title: Infrared thermography as a tool to evaluate body surface temperature and its relationship with feed efficiency in Bos indicus cattle in tropical conditions.
abstract: The aims of this study were to evaluate the use of infrared thermography (IRT) images as a tool for monitoring body surface temperature and to study its relationship with residual feed intake (RFI) in Nellore cattle. We also evaluated IRT as an indicator of feed efficiency in Bos indicus cattle. In this study, 144 Nellore steers were fed high-concentrate diets for 70 days to evaluate feedlot performance. We examined nine animals classified as high RFI and nine animals classified as low RFI by measuring rectal temperature (RT), respiratory frequency (RF), and IRT in the front, eye, ocular area, cheek, flank, ribs, rump, and front feet. The measurements were taken at 0700, 1200, and 1600 hours. The IRT temperatures measured at the eye, cheek, flank, ribs, rump, and front feet were positively associated with RF and RT. These results indicate that increases in the temperatures are associated with increased RF and RT. There was an effect in the RFI group in the front region where IRT correlates with RT. The front IRT for high-RFI cattle was lower (P < 0.01) than that for low-RFI cattle. The higher skin temperature measured by IRT for animals in the RFI group may be related to improved efficiency of thermoregulatory mechanisms because the RT remained lower in the low-RFI group. IRT can be used in the head for studies related to RFI in beef cattle.
authors.affiliation: Department of Biosystems Engineering, University of São Paulo (FZEA/USP), Pirassununga Campus, Pirassununga, SP, Brazil. martello@usp.br.
authors.forename: Luciane Silva
authors.initials: LS
authors.lastname: Martello
authors.affiliation: Department of Animal Science, University of São Paulo (FZEA/USP), Pirassununga Campus, Pirassununga, SP, Brazil.
authors.forename: Saulo
authors.initials: S
authors.lastname: da Luz E Silva
authors.affiliation: Embrapa Beef Cattle, Campo Grande, MS, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: da Costa Gomes
authors.affiliation: Department of Animal Science, University of São Paulo (FZEA/USP), Pirassununga Campus, Pirassununga, SP, Brazil.
authors.forename: Rosana Ruegger Pereira
authors.initials: RR
authors.lastname: da Silva Corte
authors.affiliation: Department of Biosystems Engineering, University of São Paulo (FZEA/USP), Pirassununga Campus, Pirassununga, SP, Brazil.
authors.forename: Paulo Roberto
authors.initials: PR
authors.lastname: Leme
mesh_terms: D000821:Animal Feed; D000822:Animal Husbandry; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004435:Eating; D007259:Infrared Rays; D008297:Male; D012881:Skin Temperature; D013817:Thermography; D014329:Tropical Climate
keywords: Beef cattle; Infrared image; Residual feed intake; Thermoregulation