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Influence of beef production practices on meat quality characteristics and expression of genes related to collagen synthesis and degradation in the bovine m. triceps brachii
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- Author / Creator
- Ijiwade, Esther. O.
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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. Two studies were conducted to examine the effects of breed type and RFI on meat quality and collagen characteristics of beef and the how the expression of genes related to collagen synthesis and degradation are related to collagen characteristics and meat quality attributes of triceps brachii, a muscle from the chuck characterized with high intramuscular connective tissue. 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 m. triceps brachii. Each breed had high RFI and low RFI steers (n=12 each) 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 genetic selection of low RFI animals on triceps brachii muscle were limited although post-mortem ageing for 13 days reduced Warner-Bratzler shear force, a measure of toughness, and increased collagen heat solubility.
In the second study, 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 are 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 housekeeping (18s ribosomal RNA) genes were calculated (∆CT). Surprisingly, Angus beef steers, a breed known for its superior marbling and tenderness had higher expression of collagen types genes COL1A1, COL5A1, COL6A1, and genes involved in collagen and collagen cross-links synthesis such as FGF2, FGFR1, LOX, LH, ITGA1, ITGB1, P4HA1, SMAD2, SMAD3, SMAD 2, SMAD 6, and SMAD 7. However, it also had higher expression of MMP genes and lower expression of TIMP genes. Expression of FGFR1 and ITGA1 genes were related to increased beef toughness of m. triceps brachii early post-mortem at day 3 of ageing. To increase the value and overall eating quality of m. triceps brachii, extending post-mortem ageing periods of the muscle is recommended. These results indicate that further research to understand mechanism controlling the expression of FGFR1, ITGA1, TIMPs and MMPs may be important to prevent excessive collagen and mature collagen cross-links accumulation. -
- Graduation date
- Spring 2020
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.