Citation
Fong, Michelle Wai Cheng
(2019)
Meat quality, meat fatty acid composition, and effects of transport stress on crossbred pigs in Malaysia.
Doctoral thesis, Universiti Putra Malaysia.
Abstract
Pork meat quality and local genetic diversity of pigs is relatively unknown in
Malaysia since the abolishing of designated breeder farms and centralized
suppliers since the Nipah virus outbreak in Malaysia. This is compounded by
the presence of unlicensed slaughterhouses, which threatens the quality of
pork for the consumer. This study seeks to determine the general pork quality
from model farms in Malaysia, as well as the effect of transportation duration
on meat quality, stress parameters and HSP70 expression. This study also
compares the Warner-Bratzler Shear Force (WBSF) values between the
roasted and boiled meat to approximate local consumer preference and
laboratory meat quality evaluation method.
Meat quality parameters were evaluated from the longissimus dorsi of 10
Duroc crossbreeds to estimate that the local pork quality falls into the category
of Red, Soft and Exudative meat (acceptable with mild defects). The fatty acid
profile analysis done on the longissimus dorsi of 6 Landrace pure breed, 4
Large White pure breed and 10 Duroc crossbreds showed that the Duroc
crossbreds have the lowest saturated fatty acid content and the highest
unsaturated fatty acid to saturated fatty acid ratio compared to pure breeds.
However, producers may need to increase the polyunsaturated fatty acid
omega 3 (PUFA n-3) levels in Duroc crosses due to high PUFA n-6: n-3 ratio.
As for the effects of transportation, 20 Duroc crosses were assigned to long
transportation stress (3-hour transportation duration), while 10 Duroc
crossbreds were subjected to short transportation stress (30-minute
transportation duration). A transportation duration of 3 hours is correlated with
high serum corticosterone levels, down-regulation of heat shock protein 70 (HSP70) expression, higher tendency of muscle lipid oxidation and lower
pH45minutes when compared to the short transportation group. This study
suggests that the initial stress caused by short transportation durations of 30
minutes up-regulates the expression of HSP70 for cellular repair mechanism.
This mechanism is severely impacted after 3 hours of transportation stress,
leading to the downregulation of HSP70 and the tendency of increased cellular
oxidative potential in the muscle.
In conclusion, the proposed pork quality baseline reference falls within the
RSE category, still deemed satisfactory in terms of consumer perception with
Duroc cross still demonstrating consumer preferable meat quality and fatty
acid composition compared to the other breeds. Results heavily suggests
keeping the transportation time limit to within 3 hours to reduce further
negative impact on meat quality. These may be achieved contributing to the
benefits of the establishments of pig farming areas (PFA) within the country.
HSP70 gene expression may be potentially used as a biomarker for drip loss.
This study also suggests a pathway where the expression of HSP70 can be
associated with changes in meat quality supported by high correlations. This
study presents pork quality from Malaysian model pig farms to serve as a
guideline to other pork producers, as well as provides insight into how
transportation duration impacts ultimate meat quality.
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