Effects of supplemental methionine and zinc on feedlot performance, carcass characteristics, muscle satellite cells, protein extraction and rumen morphometrics of cattle fed high-grain diets

Abstract

This study is designed to determine the effects of supplemental methionine and zinc on feedlot performance, carcass characteristics, muscle satellite cells, protein extraction and rumen morphometrics of cattle fed high-grain diets. The trial will be conducted at Texas Tech University, Lubbock, USA. One hundred forty-four British-crossbred steers (Initial body weight = 360 kg) will be housed in 36 pens (2.9 m width × 5.5 m length; 2.4 m of linear bunk space), and fed for 134 days. The experimental design will be a completely randomized block with 2 × 2 factorial arrangements. Factors will be inclusion (dry matter basis) or not of either methionine or zinc, according to treatments: 1) Control; 2) Methionine (12.24 g/steer·d-1); 3) Zinc (1.0 g/steer·d-1) and 4) Methionine + Zinc (at same dosage described previously). Pens will be considered experimental unit for this study (n = 36; 4 steers per pen), and each treatment will be replicated 8 times. Initial body weight will be utilized as a criterion for block formation. In this study the following variables will be evaluated: 1) feedlot performance and carcass characteristics; 2) muscle satellite cells and protein extraction; 3) rumen morphometrics.