title: Effects of castration age, dietary protein level and lysine/methionine ratio on animal performance, carcass and meat quality of Friesian steers intensively reared.
abstract: The effects of castration age, dietary protein level and the dietary lysine/methionine (lys/met) ratio on animal performance, carcass characteristics and meat quality were studied in 64 intensively reared Friesian steers. Animals underwent castration procedures at 15 days old or at 5 months old. Dietary treatments started at 90 days old, with eight animals from each castration age randomly allocated to each treatment: 14.6% v. 16.8% CP (DM basis), and 3.0 v. 3.4 lys/met, on a 2×2×2 design. The recommended ratio of 3.0 was reached with supplementation of protected methionine. Steers were slaughtered at 443.5±26.2 kg live weight when they reached 12 months old approximately. Average daily gain, cold carcass weight or carcass classification were not affected by any studied effect. Muscle moisture (P=0.024), C18:2n-6 percentage (P=0.047), polyunsaturated fatty acid/saturated fatty acid (P=0.049) and n-6/n-3 (P=0.003) were higher in late castrated animals. Both high levels of dietary protein (P=0.008) and lys/met ratio (P=0.048) increased the percentage of muscle in the carcass. A level of 16.8% of CP in the diet also increased the percentage of monounsaturated fatty acids in the intramuscular fat (P=0.032), whereas a ratio lys/met of 3.4 decreased the percentage of saturated fatty acids (P=0.028). Thus, it is recommended using diets with a high protein level (16.8%) and a high lys/met ratio (3.4) in animals slaughtered at a young age, in order to obtain carcasses with high muscle content without negatively affecting productive traits or intramuscular fat composition.
authors: 1Department of Animal Production and Food Science,University of Zaragoza,Miguel Servet 177,50013 Zaragoza,Spain.
authors: I N
authors: IN
authors: Prado
authors: 1Department of Animal Production and Food Science,University of Zaragoza,Miguel Servet 177,50013 Zaragoza,Spain.
authors: M M
authors: MM
authors: Campo
authors: 1Department of Animal Production and Food Science,University of Zaragoza,Miguel Servet 177,50013 Zaragoza,Spain.
authors: E
authors: E
authors: Muela
authors: 1Department of Animal Production and Food Science,University of Zaragoza,Miguel Servet 177,50013 Zaragoza,Spain.
authors: M V
authors: MV
authors: Valero
authors: 3Industrial Zootécnica Aragonesa (INZAR),Poeta Luís Cernuda sn,50018 Zaragoza,Spain.
authors: O
authors: O
authors: Catalan
authors: 1Department of Animal Production and Food Science,University of Zaragoza,Miguel Servet 177,50013 Zaragoza,Spain.
authors: J L
authors: JL
authors: Olleta
authors: 1Department of Animal Production and Food Science,University of Zaragoza,Miguel Servet 177,50013 Zaragoza,Spain.
authors: C
authors: C
authors: Sañudo
mesh_terms: D000367:Age Factors; D000821:Animal Feed; D000818:Animals; D001823:Body Composition / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D004044:Dietary Proteins / Q000008:administration & dosage*; D019587:Dietary Supplements; D005227:Fatty Acids / Q000032:analysis; D008239:Lysine / Q000008:administration & dosage*; D008297:Male; D008460:Meat / Q000592:standards*; D008715:Methionine / Q000008:administration & dosage*; D009919:Orchiectomy; D011897:Random Allocation
chemical_list: D004044:Dietary Proteins; D005227:Fatty Acids; D008715:Methionine; D008239:Lysine