Salvador Reyes | ALES Graduate Seminar

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 Salvador Reyes. This seminar is open to the general public to attend.
Thesis Topic: Effect of breed type and residual fee intake on meat and collagen quality and expression of genes related to collagen synthesis and degradation in bovine m. gluteus medius

MSc with Dr. Heather Bruce.

Seminar Abstract:

One feed efficiency index that has been used for selecting beef cattle is residual feed intake (RFI). This index has been demonstrated to be moderately heritable, with cattle having low RFI values being most efficient; therefore, these cattle consume less feed for the same weight gain and this may benefit the beef producer because the cost of animal diet decreases by about 9%.  To be fully beneficial to producers, selection for low RFI should not compromise meat quality. One of the most important characteristics of meat quality is tenderness, for which the consumer is willing to pay a premium. Collagen is known to be involved in determining the background toughness of meat and this may be affected by cattle breed type, selection for residual feed intake, and post-mortem ageing.  Seventy-two (72) steers from three different breeds (Angus n = 24, Charolais n = 24, and Kinsella Composite n = 24) were used to investigate the interaction between RFI within cattle breed type on meat quality and intramuscular collagen characteristics of the m. gluteus medius after 3 and 13 days of post mortem ageing. The results indicated that RFI did not affect meat pH, colour, drip loss, sarcomere length and Warner-Bratzler shear force, and that intramuscular collagen heat solubility increased with selection for low RFI. These results implied that beef producers can use this feed efficiency index to select for low RFI cattle without compromising meat quality.

From within the 72 steers, 12 steers from each breed (total n = 36) were selected for high (n = 6) and low (n = 6) collagen heat solubility.  Intramuscular RNA was isolated from the m. gluteus medius and the expression levels of 38 genes related to collagen synthesis and degradation were determined and related to meat quality and collagen characteristics. The expression of genes involved in collagen biosynthesis and degradation were unrelated to collagen solubility but were affected by breed type, suggesting physiological age differences existed between the breed types that may affect the background toughness of the m. gluteus medius.