title: Feed efficiency indexes and their relationships with carcass, non-carcass and meat quality traits in Nellore steers.
abstract: Five hundred and seventy-five Nellore steers were evaluated for residual feed intake and residual feed intake and gain and their relationships between carcass, non-carcass and meat quality traits. RFI was measured by the difference between observed and predicted dry matter intake and RIG was obtained by the sum of -1*RFI and residual gain. Efficient and inefficient animals were classified adopting ±0.5 standard deviations from RFI and RIG mean. A mixed model was used including RFI or RIG and contemporary group as fixed effects, initial age as covariate and sire and experimental period as random effects, testing the significance of the regression slope for each evaluated trait. RIG was positively related to longissimus muscle area. Efficient-RFI animals had lower liver and internal fat proportions compared to inefficient-RFI animals. Efficient-RFI and efficient-RIG animals had 11.8% and 11.2% lower extracted intramuscular fat, compared to inefficient-RFI and inefficient-RIG animals, respectively. Efficient-RFI animals had tougher meat compared to inefficient-RFI animals.
authors.affiliation: Department of Animal Science, University of São Paulo/ESALQ, Piracicaba, São Paulo 13418-900, Brazil.
authors.forename: M L
authors.initials: ML
authors.lastname: Nascimento
authors.affiliation: Department of Animal Science, University of São Paulo/ESALQ, Piracicaba, São Paulo 13418-900, Brazil.
authors.forename: A R D L
authors.initials: AR
authors.lastname: Souza
authors.affiliation: Department of Animal Science, University of São Paulo/ESALQ, Piracicaba, São Paulo 13418-900, Brazil. Electronic address: amaliaschaves@yahoo.com.br.
authors.forename: A S
authors.initials: AS
authors.lastname: Chaves
authors.affiliation: Department of Animal Science, University of São Paulo/ESALQ, Piracicaba, São Paulo 13418-900, Brazil.
authors.forename: A S M
authors.initials: AS
authors.lastname: Cesar
authors.affiliation: Embrapa Southeast Livestock, São Carlos, SP 13560-970, Brazil.
authors.forename: R R
authors.initials: RR
authors.lastname: Tullio
authors.affiliation: Embrapa Beef Cattle, Campo Grande, MS 79106-550, Brazil.
authors.forename: S R
authors.initials: SR
authors.lastname: Medeiros
authors.affiliation: Department of Animal Science, University of São Paulo/ESALQ, Piracicaba, São Paulo 13418-900, Brazil.
authors.forename: G B
authors.initials: GB
authors.lastname: Mourão
authors.affiliation: Embrapa Beef Cattle, Campo Grande, MS 79106-550, Brazil.
authors.forename: A N
authors.initials: AN
authors.lastname: Rosa
authors.affiliation: Embrapa Beef Cattle, Campo Grande, MS 79106-550, Brazil.
authors.forename: G L D
authors.initials: GL
authors.lastname: Feijó
authors.affiliation: Embrapa Southeast Livestock, São Carlos, SP 13560-970, Brazil.
authors.forename: M M
authors.initials: MM
authors.lastname: Alencar
authors.affiliation: Department of Animal Science, University of São Paulo/ESALQ, Piracicaba, São Paulo 13418-900, Brazil.
authors.forename: D P D
authors.initials: DP
authors.lastname: Lanna
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001823:Body Composition / Q000502:physiology*; D002417:Cattle / Q000235:genetics / Q000502:physiology; D004032:Diet / Q000662:veterinary; D008297:Male; D008460:Meat / Q000592:standards*
keywords: Beef cattle; Bos indicus; Feed efficiency; Internal fat; Tenderness; Visceral organs