title: Prediction of physical and chemical body compositions of purebred and crossbred Nellore cattle using the composition of a rib section.
abstract: The goal of this research was to develop empirical equations to predict chemical and physical compositions of the carcass and the body using the composition of the 9th- to 11th-rib section (rib(9-11)) and other measurements. A database (n = 246) from 6 studies was developed and comprised 37 bulls (BU), 115 steers (STR), and 94 heifers (HF), of which 132 were Nellore (NEL), 76 were NEL × Angus crossbreds (NA), and 38 were NEL × Simmental crossbreds (NS). The right half carcass and the rib(9-11) from the left half carcass were analyzed for ether extract (EE), CP, and water. The remaining components were chemically analyzed to determine the composition of the body. A stepwise procedure was used to determine the variable inclusion in the regression models. The variables included were EE in the rib(9-11) (EER; %), CP in the rib(9-11) (CPR; %), water in the rib(9-11) (WR; %), visceral fat (VF; %; KPH and mesenteric fats), organs plus viscera (OV; %), carcass dressing percentage (CD; %), cold carcass weight (kg), and empty BW (EBW; kg). No sex or breed effects were found on EE and CP compositions of the carcass (C(EE) and C(CP), respectively; %); the equations were as follows: C(EE) = 4.31 + 0.31 × EER + 1.37 × VF [n = 241; R(2) = 0.83; mean square error (MSE) = 4.53] and C(CP) = 17.92 + 0.60 × CPR - 0.17 × CD (n = 238; R(2) = 0.50; MSE = 1.58). Breed affected water content in the carcass (C(W), %); the equations were as follows: C(W) = 48.74 + 0.28 × WR - 0.017 × EBW for NEL; C(W) = 46.69 + 0.32 × WR - 0.017 × EBW for NA; and C(W) = 38.06 + 0.48 × WR - 0.017 × EBW for NS (n = 243; R(2) = 0.67; MSE = 5.17). A sex effect was found on body chemical EE composition (BW(EE)); the equations were as follows: BW(EE) = 2.75 + 0.33 × EER + 1.80 × VF for BU; BW(EE) = 1.84 + 0.33 × EER + 1.91 × VF for STR; and BW(EE) = 4.77 + 0.33 × EER + 1.28 × VF for HF (n = 243; R(2) = 0.89; MSE = 3.88). No sex or breed effects were found on CP composition in the body (BW(CP)); the equation was as follows: BW(CP) = 14.38 + 0.24 × CPR (n = 240; R(2) = 0.59; MSE = 1.06). A sex effect was found for body water content (BW(W)); the equations were as follows: BW(W) = 38.31 + 0.33 × WR - 1.09 × VF + 0.50 × OV for BU; BW(W) = 45.67 + 0.25 × WR - 1.89 × VF + 0.50 × OV for STR; and BW(W) = 31.61 + 0.47 × WR - 1.06 × VF + 0.50 × OV for HF (n = 241; R(2) = 0.81; MSE = 3.84). The physical carcass composition indicated a breed effect on all components and a sex effect for fat in the carcass. We conclude that body and carcass compositions can be estimated with rib(9-11) for purebred and crossbred NEL animals, but specific equations have to be developed for different groups of animals.
authors.affiliation: Texas A&M University, Department of Animal Science, College Station 77843-2471, USA. marcosinaciomarcondes@gmail.com
authors.forename: M I
authors.initials: MI
authors.lastname: Marcondes
authors.forename: L O
authors.initials: LO
authors.lastname: Tedeschi
authors.forename: S C
authors.initials: SC
authors.lastname: Valadares Filho
authors.forename: M L
authors.initials: ML
authors.lastname: Chizzotti
mesh_terms: D000818:Animals; D001823:Body Composition; D050218:Body Fat Distribution / Q000662:veterinary; D001834:Body Water / Q000737:chemistry; D002417:Cattle / Q000378:metabolism*; D005260:Female; D008297:Male; D008460:Meat / Q000032:analysis; D012272:Ribs / Q000737:chemistry*; D012737:Sex Factors; D013045:Species Specificity