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Asian-Australas J Anim Sci > Accepted Articles
DOI: https://doi.org/10.5713/ajas.19.0822    [Accepted] Published online February 25, 2020.
Effect of crude protein content and undegraded intake protein level on productivity, blood metabolites, carcass characteristics, and production economics of Hanwoo steer
Youn Hee Lee1  , Farhad Ahmadi1  , Myun Lee1  , Young-Kyoon Oh2  , Wan Sup Kwak1,* 
1Department of Food Bio-science, College of Medical Life Sciences, Konkuk University, 268 Chungwon-daero, Chungju, Chung-Buk 380–701, Korea
2Animal Nutrition & Physiology Team, National Institute of Animal SAnimal Nutrition & Physiology Team, National Institute of Animal Science, Rural Development Administration, Wanju county, Jeon-Buk province 565–851, Korea
Correspondence:  Wan Sup Kwak, Tel: +82-043-840-3521, Fax: +82-043-851-8675, Email: wsk@kku.ac.kr
Received: 21 October 2019   • Revised: 3 December 2019   • Accepted: 22 January 2020
This study was designed to determine how feeding diets differing in crude protein (CP) and undegraded intake protein (UIP) levels affected productivity, blood metabolites, carcass characteristics, and the production economics of Hanwoo steers.
Thirty-six Hanwoo steers (age = 8.2 ± 0.5 mo; body weight = 254 ± 16.1 kg) were assigned at random to one of three treatments (4 steers/pen; 3 pens/treatment): 1) a low-CP diet (LP; control) containing 12.1% CP with 35.1% UIP, 12.0% CP with 36.8% UIP, and 12.9% CP with 48.8% UIP, in the growing, fattening, and finishing periods, respectively; 2) a high-CP, low-UIP diet (HPLU) containing 15.0% CP with 33.7% UIP, 14.0% CP with 35.7% UIP, and 13.1% CP with 46.7% UIP, respectively; and 3) a high-CP, high-UIP diet (HPHU) containing 15.0% CP with 45.8% UIP, 14.0% CP with 44.6% UIP, and 13.0% CP with 51.1% UIP, respectively.
The treatments did not affect feed intake and growth performance, with the exception of average daily gain during the fattening period that tended to be the lowest (p = 0.08) in the HPLU-fed steers. The feed CP conversion ratio over the entire feeding period was higher with high-CP diets. The treatments did not affect the majority of blood metabolites; however, blood cholesterol and low-density lipoprotein concentrations during the fattening and finishing periods were the lowest in steers fed a HPLU diet. The treatments had negligible effects on cold carcass weight, yield traits including longissimus muscle area, backfat thickness, yield index, and yield grade, plus quality traits including meat color, fat color, texture, and maturity. However, marbling score and frequency of carcass quality grade 1++ were greater in HPHU-fed steers.
Feeding diets with higher CP and UIP levels did not affect growth performance, but tended to improve the carcass quality of Hanwoo steers, resulting in greater economic return.
Keywords: Carcass Quality; Crude Protein; Hanwoo; Marbling; Undegraded Intake Protein

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