The Rural Voice, 2001-05, Page 55management will depend on a lot of
- factors such as the herbicide choice,
the types of crops and the type of
weed infestations.
When you have resistance, what
do you do about it? If you don't have
resistance, how do you prevent it?
For the most part the answers to both
questions are the same. Here are
some ideas on managing weed
resistance:
• Avoid using the same herbicide or
herbicides from the same grouping in
the same field, in consecutive years.
• Do not use the same mode of action
more than once per season. Rescue
sprays should be from a different
herbicide group.
• Use tank mixes where two or more
products give effective control
against the target weed, and the
products are from different mode of
action groupings.
• Use crop rotation, changing
herbicides is not enough. Different
crops allow for a broader spectrum of
herbicide and tillage options to
control weeds. Some crops are more
aggressive than others to compete
against weeds.
• Manage weed escapes effectively.
Note trends, successes, and failures.
• Use clean seed. Clean equipment
when moving field to field.
• Where possible use cultivation,
cover crops, or other practices to
reduce viable weed seeds in the soil.0
How the pH in meat
affects final
pork quality
By Wayne Du, OMAFRA, Fergus
Why is pH important to pork
quality?
pH has a high influence on water
holding capacity (WHC), which is
closely related to product yield and
pork quality. WHC is the ability of
meat to retain its water during
processing, storage and cooking.
Low WHC often results in high drip
Toss and poor eating quality (dryer
and tougher in the cooked state).
Water loss means a loss of saleable
product yield. In extreme cases, this
weight loss could reach as high as
10% or more. In addition, pork with
Advice
low WHC does not hold a cure as
well, a fact troubling to processors.
pH affects the color of pork. A
low meat pH is often associated with
low WHC and pale meat color. While
high meat pH often causes a dark
meat color, both pale and dark colors
are unattractive pork colors to
consumers. In addition, pork with
pale color and low pH often has a
metallic and off -flavor taste.
Conversely, dark pork is high in pH
and has a shorter shelf life than the
normal reddish -pink colour that
consumers prefer their fresh pork to
be.
How does pH affect pork quality?
Changes in meat pH result from
post mortem metabolism (glycolysis)
and the conversion of glycogen into
lactic acid. Variation in the rate
and/or the extent of post mortem
glycolysis is responsible for a major
proportion of the variation in meat
WHC and color. Pork with normal
color and WHC reaches an ultimate
pH of 5.6 to 5.7 within
approximately three to five hours
after slaughter. In contrast, Pale, Soft
and Exudative (PSE) pork is caused
by a very rapid drop in pH
immediately after slaughter while
muscle temperatures are still high.
This combination of relatively low
pH and high temperature results in
proteins being denatured, which
reduces WHC and results in a pale
color. On the other hand, high meat
pH (above 6.0 to 6.2) often causes
dark, firm and dry (DFD) pork.
What are the main factors affecting
meat pH and pork quality?
Low WHC and pale color often
result from a rapid drop in ultimate
meat pH which is triggered by a
combination of a number of factors,
such as genetics, pre -slaughter stress
and post -slaughter handling. While
the DFD condition results from low
glycogen levels in the muscle at
slaughter due to glycogen depletion
that occurs from a combination of
chronic stress and activity levels
before slaughter.
Genetics of the pigs
Two genetic defects associated
with low meat pH are Halohane and
Rendement Napole (RN) genes. It is
well known that pigs that carry the
Halohane gene produce more PSE,
while pigs that carry the RN gene can
cause acid meat. which results from a
more extensive decline in muscle pH
and an abnormally low ultimate pH
in the muscle. In appearance, acid
meat is very like PSE meat being
pale and having a low WHC.
Pre -slaughter stress
Pre -slaughter stress plays an
important role on pork quality. Pork
quality can be severely damaged
during the last five minutes prior to
stunning. PSE increases if hogs are
handled roughly prior to slaughter.
Pork quality can be improved by
taking the following measures:
• Loading and unloading market hogs
quietly;
• Using proper loading density, don't
over load or under load pigs;
• Providing enough space in holding
pens at the plant, approximately .55
M2 per 110 kg pig so pigs can lie
down for rest;
• Wetting and cooling animals down
with sprinklers during hot weather;
• Resting pigs for 2-4 hours prior to
slaughter;
• Allowing hogs access to water all
the time;
• Reducing and eliminating the use of
electric prods.
Post -slaughter handling
The outmost consideration after
slaughter is to cool the carcass or
muscles down as early and as fast as
possible. Poor chilling at the
slaughter plant increases PSE.O
Census day coming
May 15
May 15, 2001 is Census Day in
Canada.
In early May, farm operators
across Canada will receive a Census
of Agriculture questionnaire and a
Census of Population questionnaire.
The Census of Agriculture
provides vital information that
supports decisions made at all levels
of the agricultural industry. The
confidentiality of the information you
provide on your Census of
Agriculture form is protected by
law.0
MAY 2001 51