1:30 pm - 2:30 pm
318J Agriculture/Forestry Centre (AgFor), Agriculture/Forestry Centre, Edmonton AB
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 Esther Ijiwade. This seminar is open to the general public to attend.
Thesis Topic: Influence of breed production practices on meat quality characteristics and expression of genes related to collagen synthesis and degradation in the bovine m. triceps brachii.
MSc with Dr. Heather Bruce.
Triceps brachii, a muscle from the chuck in the beef carcass, is an underutilized cut characterized by high amounts of intramuscular connective tissue (IMCT), and therefore perceived to be tough. Collagen, the most abundant protein present in IMCT forms cross-links over time which become less heat soluble, hence increasing cooked beef toughness. Production factors such as cattle breed, genetics, age, feed, muscle activity and processing factor such post-mortem ageing may affect the contribution of collagen and collagen cross-links to beef toughness. Selection of low residual feed intake (RFI) cattle, which consume less feed than expected, to reduce the cost of production would only be beneficial if it has no negative effect on the quality attributes of beef. For the first study, seventy-one beef steers from Angus (n=23), Charolais (n=24) and Angus crossbred (n=24) genetics were used to examine the influence of breed type, residual feed intake (RFI) and post-mortem ageing on meat and carcass quality attributes and intramuscular connective tissue characteristics in the bovine Triceps brachii muscle. Each breed had high RFI and low RFI steers (n=12) to test the hypothesis that genetic selection for low RFI beef cattle may increase collagen content, reduce collagen heat solubility and increase beef toughness of the Triceps brachii muscle. The effects of breed type and the genetic selection of low RFI animals on Triceps brachii muscle were limited, however, post-mortem ageing for 13 days reduced Warner-Bratzler shear force, a measure of toughness, and increased collagen heat solubility.
Twenty-four beef steers (Angus (n = 8), Charolais (n = 8) and Angus crossbred (n = 8) with low and high intramuscular collagen solubility at 3 days post mortem (dpm) were used to test the effects of breed type and solubility level on genes involved in the synthesis and degradation of collagen. The hypothesis that phenotypic measurements of meat quality attributes and intramuscular connective tissue characteristics will be related to differences in the expression level of target genes was tested. Expression levels of 27 candidate genes were evaluated using quantitative real time polymerase chain reaction (RT-qPCR) and the mean differences in expression between candidate and normalization (18s ribosomal RNA) genes were calculated (. The results showed that breed type affected expression levels of the target genes while gene expression was unrelated to collagen heat solubility, and that genes associated with increased collagen synthesis and decreased degradation were related to increased beef toughness in triceps brachii muscle.