title: Beef palatability and its relationship with protein degradation and muscle fibre type profile in longissimus thoracis in Alentejana breed from divergent growth pathways.
abstract: The traditional beef production in the South of Portugal is based on a discontinuous growth (DG) system that requires lower external inputs and could enhance meat quality and financial returns to cattle producers. This system allows farmers to take advantage of the bull's compensatory growth when the pasture is abundant and finishes the cattle on concentrates for 2 to 3 months before slaughter. The fast gain rate before slaughter could be a valuable strategy to improve tenderness and to reduce its inconsistency in beef production. Therefore, the aim of this study was to evaluate the effects of production system (continuous growth (CG) v. DG) on longissimus thoracis muscle properties from Alentejana bulls. In total, 40 Alentejana male calves were allocated to two distinct feeding regimes: in the CG system, animals were fed concentrate plus hay and slaughtered at 18 months of age, whereas in the DG system, animals were fed on hay until 15 months of age and then fed the same diet provided to the CG group until 24 months of age. The DG system had a positive impact on meat tenderness (P<0.001) and global acceptability (P<0.001). DG bulls had greater fibre cross-sectional area (CSA) of glycolytic fibres (P<0.05) and relative area of the muscle (RA) occupied by type IIX fibres (P<0.01) and greater levels of α-actinin (P<0.05) and myosin light chain 2 (P<0.01) proteins, and pH24h (P<0.01) than CG bulls. The latter had greater CSA of type I (P<0.05) and type IIA (P<0.01) and greater RA of type IIA (P<0.05) and oxidative (P<0.05) than CG bulls. The compensatory growth production system had a positive impact on meat tenderness and global acceptability, overcoming the negative effects of slaughter of the bulls at a later age. The DG beef system could be a worthwhile strategy of beef production in Mediterranean areas due to the low-quality pasture in summer.
authors.affiliation: 1CIISA - Faculdade de Medicina Veterinária,Universidade de Lisboa,Avenida da Universidade Técnica,Pólo Universitário do Alto da Ajuda,1300-477 Lisboa,Portugal.
authors.forename: P
authors.initials: P
authors.lastname: Costa
authors.affiliation: 2L-INIAV Santarém,Instituto Nacional dos Recursos Biológicos,Quinta da Fonte Boa,2005-048 Vale de Santarém,Portugal.
authors.forename: J A
authors.initials: JA
authors.lastname: Simões
authors.affiliation: 1CIISA - Faculdade de Medicina Veterinária,Universidade de Lisboa,Avenida da Universidade Técnica,Pólo Universitário do Alto da Ajuda,1300-477 Lisboa,Portugal.
authors.forename: S P
authors.initials: SP
authors.lastname: Alves
authors.affiliation: 1CIISA - Faculdade de Medicina Veterinária,Universidade de Lisboa,Avenida da Universidade Técnica,Pólo Universitário do Alto da Ajuda,1300-477 Lisboa,Portugal.
authors.forename: J P C
authors.initials: JP
authors.lastname: Lemos
authors.affiliation: 1CIISA - Faculdade de Medicina Veterinária,Universidade de Lisboa,Avenida da Universidade Técnica,Pólo Universitário do Alto da Ajuda,1300-477 Lisboa,Portugal.
authors.forename: C M
authors.initials: CM
authors.lastname: Alfaia
authors.affiliation: 1CIISA - Faculdade de Medicina Veterinária,Universidade de Lisboa,Avenida da Universidade Técnica,Pólo Universitário do Alto da Ajuda,1300-477 Lisboa,Portugal.
authors.forename: P A
authors.initials: PA
authors.lastname: Lopes
authors.affiliation: 1CIISA - Faculdade de Medicina Veterinária,Universidade de Lisboa,Avenida da Universidade Técnica,Pólo Universitário do Alto da Ajuda,1300-477 Lisboa,Portugal.
authors.forename: J A M
authors.initials: JA
authors.lastname: Prates
authors.affiliation: 3INRA,UR 1213,Unité de Recherches sur les Herbivores (URH),Theix,F-63122 Saint-Genés Champanelle,France.
authors.forename: J F
authors.initials: JF
authors.lastname: Hocquette
authors.affiliation: 5Department of Animal Science,University of Nebraska,Lincoln,NE 68583-0908,USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Calkins
authors.affiliation: 6CIPER - Faculdade de Mótricidade Humana,Universidade de Lisboa,Estrada da costa,Cruz Quebrada-Dafundo,1499-002 Lisboa,Portugal.
authors.forename: V
authors.initials: V
authors.lastname: Vleck
authors.affiliation: 1CIISA - Faculdade de Medicina Veterinária,Universidade de Lisboa,Avenida da Universidade Técnica,Pólo Universitário do Alto da Ajuda,1300-477 Lisboa,Portugal.
authors.forename: R J B
authors.initials: RJ
authors.lastname: Bessa
mesh_terms: D000822:Animal Husbandry / Q000191:economics; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001947:Breeding; D002417:Cattle / Q000235:genetics / Q000254:growth & development; D004032:Diet / Q000662:veterinary; D006019:Glycolysis; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D009124:Muscle Proteins / Q000378:metabolism; D011174:Portugal; D059748:Proteolysis; D000069466:Red Meat / Q000592:standards*
chemical_list: D009124:Muscle Proteins
keywords: bulls; compensatory growth; meat sensory characteristics; muscle fibre traits; muscle protein fragments