9:00 am - 10:00 am
318-J Agriculture/Forestry Centre, Agriculture/Forestry Centre, Edmonton
A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Olalekan Laguda. This seminar is open to the general public to attend.
Thesis Topic: Trained panel sensory evaluation of m. longissimus thoracis, m. gluteus medius and m. semimembranosus from Angus crossbred steers: the influence of hormonal growth promotants, ractopamine hydrochloride, and selection for high or low residual feed intake
MSc with Dr. Heather Bruce.
Selection of cattle for residual feed intake (RFI) does not affect rate of gain; rather, low RFI cattle consume less feed than high RFI animals to attain a similar final body weight and are thus considered feed efficient. Reducing production costs by selecting low RFI cattle and incorporating hormonal growth promotants (HGP) or beta-adrenergic agonists (BA) into beef production programs will only be beneficial to the beef industry if meat quality is not adversely affected. The objective of this study was to identify the effects of genetic selection for residual feed intake and its interactions with growth promotant use and ractopamine hydrochloride on the sensory characteristics of beef from one low and two high connective tissue muscles. Trained sensory panelists evaluated the meat quality characteristics of m. longissimus thoracis (LT) m. gluteus medius (GM) and m. semimembranosus (SM) from carcasses of Angus crossbred steers treated with HGP and/or BA and selected for high or low RFI. Forty-eight Angus crossbred steers, 21 high RFI and 27 low RFI, were either implanted twice with HGP (treated) or not (control) and received either ractopamine at 200 mg/head/day for the last 28 days of finishing (treated) or not (control) in a 2 x 2 x 2 factorial design. Half of each muscle, balanced for position within the muscle, was aged for either 3 or 12 days post-mortem before assessment for sensory characteristics. Overall tenderness scores for all the samples were acceptable, but aged samples had the highest acceptance. The results further showed that steaks from animals that were treated with HGP were the toughest, while steaks from animals that were either treated with ractopamine hydrochloride (RAC) or not treated produced the most tender beef regardless of muscle type. A similar relationship was observed for juiciness with HGP steaks found to be the least juicy by the panelists while steak from steers with no treatment or only RAC were the juiciest. Residual feed intake appears not to be associated with reduced meat quality, indicating that this selection measure should be able to be applied without a decrease in meat sensory quality.