title: Technical note: Assessment of the oxygen pulse and heart rate method using respiration chambers and comparative slaughter for measuring heat production of cattle.
abstract: The objective of this study was to assess the oxygen pulse and heart rate (O2P-HR) technique using the respiration chamber (RC) and comparative slaughter (CS) methods for measuring the heat production (HP) of crossbred (Holstein × Gyr) yearling bulls. Twenty-four bulls were used. Six bulls were slaughtered at the beginning of the experiment as a reference group to estimate the initial empty body weight (BW) and energy content of the remaining animals. The remaining bulls were assigned to a completely randomized design with 3 levels of dry matter intake, with 6 replicates. The levels of dry matter intake were 1.2% of BW, 1.8% of BW and ad libitum, with target orts of 5%. The bulls were fed a diet consisting of 59.6% corn silage and 40.4% concentrate on a dry matter basis. The HP (kcal/BW0.75) was measured using 3 techniques, first using O2P-HR, followed by the RC and CS methods. The HP did not differ among assessed techniques, averaging 162.7kcal/BW0.75. The intercepts of the linear regressions (mean ± SE) were 64.82±25.515 (H0: intercept=0; P=0.024), 33.77±13.418 (H0: intercept=0), and 50.02±27.495 (H0: intercept=0) for O2P-HR versus RC, CS versus RC, and O2P-HR versus CS, respectively. The slopes of the linear regressions were 0.59±0.153 (H0: slope=1), 0.88±0.081 (H0: slope=1), and 0.62±0.155 (H0: slope=1) for O2P-HR versus RC, CS versus RC, and O2P-HR versus CS, respectively. The coefficients of determination were 0.52, 0.90, and 0.52 for O2P-HR versus RC, CS versus RC, and O2P-HR versus CS, respectively. The concordance correlation coefficients, 0.70 and 0.68, were moderate for O2P-HR versus RC and O2P-HR versus CS, respectively, but high, 0.90, for CS versus RC. The between-animal coefficient of variation was greater for the O2P-HR method (16.6%) compared with RC (7.7%) or CS (6.7%). We conclude that there was an agreement among the HP measurements detected using the assessed methods and that O2P-HR is able to predict HP in cattle with great accuracy but only moderate precision. Therefore, the O2P-HR method may have limitations in terms of assessing HP in low numbers of replications due to greater between-animal coefficient of variation than either the RC or CS methods.
authors.affiliation: Universidade Federal de Viçosa, Viçosa, MG, Brazil, 36570-900; CAPES, Ministério da Educação, Brasília, DF, Brazil, 70040-020.
authors.forename: D B
authors.initials: DB
authors.lastname: Oss
authors.affiliation: Universidade Federal de Viçosa, Viçosa, MG, Brazil, 36570-900. Electronic address: marcosinaciomarcondes@gmail.com.
authors.forename: M I
authors.initials: MI
authors.lastname: Marcondes
authors.affiliation: Empresa Brasileira de Pesquisa Agropecuária, Embrapa Gado de Leite, Juiz de Fora, MG, Brazil, 36038-330.
authors.forename: F S
authors.initials: FS
authors.lastname: Machado
authors.affiliation: Empresa Brasileira de Pesquisa Agropecuária, Embrapa Gado de Leite, Juiz de Fora, MG, Brazil, 36038-330.
authors.forename: T R
authors.initials: TR
authors.lastname: Tomich
authors.affiliation: Universidade Federal de Viçosa, Viçosa, MG, Brazil, 36570-900.
authors.forename: M L
authors.initials: ML
authors.lastname: Chizzotti
authors.affiliation: Empresa Brasileira de Pesquisa Agropecuária, Embrapa Gado de Leite, Juiz de Fora, MG, Brazil, 36038-330.
authors.forename: M M
authors.initials: MM
authors.lastname: Campos
authors.affiliation: Empresa Brasileira de Pesquisa Agropecuária, Embrapa Gado de Leite, Juiz de Fora, MG, Brazil, 36038-330.
authors.forename: L G R
authors.initials: LGR
authors.lastname: Pereira
mesh_terms: D000003:Abattoirs; D000821:Animal Feed; D000818:Animals; D002417:Cattle; D004032:Diet / Q000662:veterinary; D006339:Heart Rate; D008297:Male; D010100:Oxygen; D012820:Silage; D022722:Thermogenesis; D003313:Zea mays
chemical_list: D010100:Oxygen
keywords: heart rate; heat production; oxygen pulse