Pig International - November 2017 - 25

PigInternational ❙ 25

prerequisite for efficient feed digestion and good gut health.
Neonatal pigs have a rather
high gastric pH (5 to 6) facilitated
by the strong buffering capacity
of colostrum. This might appear
contradictory to the above, but
there is a reason. A more tolerant gastric pH allows passage of
ingested environmental bacteria
(not all of them are pathogens,
after all) from the stomach to the
small and large intestines for the
establishment of normal gastrointestinal microflora. This is considered essential and even beneficial
for the animal's long-term health.
Usually, the predominant beneficial bacteria in the stomach are
lacto- and bifido-bacteria, whereas
in the intestines there is a mix of
bacteria. Nevertheless, after the
first few hours of suckling, gastric
pH drops to about 4 to remain
there until weaning, and in most
cases, during the first three to four
weeks post-weaning. Afterwards,
gastric pH drops gradually until it
reaches mature levels (2 to 3).

The benefits of early high pH
A moderate gastric pH of about
4 in suckling pigs is favorable for
the activation of chymosin (rennin),
the enzyme responsible for milkclotting in the stomach. Without
the action of chymosin, milk
would pass quickly and largely
undigested in the small intestine
where it would serve as substrate to
pathogens. Although pepsin, also a
protease, can also clot milk, albeit
at reduced efficacy than chymosin,

the latter (chymosin) has weaker
proteolytic activity. This might
again appear counterproductive,
but it is beneficial as it protects
the very important milk immunoglobulins from digestion.
Having a moderate gastric pH
also benefits proliferation of lactobacteria while excluding other
pathogenic organisms. A healthy
population of lactobacteria produces copious quantities
of lactic acid that stabilize gastric pH. However,
this results in the depression of hydrochloric acid.
In other words, in the
presence of lactic acid, there is
no incentive for the secretion of
another acid. This is one of the
reasons why many post-weaning
diets are fortified with lactic acid,
among many other organic acids. Thus, in brief, it is apparent
that suckling piglets exhibit very
limited capacity for secretion of
hydrochloric acid, which is not
strongly stimulated by sow's milk.
This is erroneously considered as
a negative aspect, but in contrast
it is important for the survival of
piglets receiving sows' milk.

Weaning upsets pH balance
At weaning, usually too early
for piglets to consume enough
creep feed, gastric pH remains
relatively high. A lower pH is required for the efficient digestion of
plant- and animal-derived proteins
(other than milk) found in most
post-weaning diets. This is because
the activity of pepsin peaks at

November/December 2017 ❙ www.WATTAgNet.com

very low pH levels about 2 to 3.5.
Some resistant proteins (mostly of
plant origin) are digested only at
the lower optimum pH, whereas
no significant digestion of any
protein source occurs above pH 4.
Provision of dairy products (mimicking the sow's milk diet preweaning) in post-weaning diets has
been shown to reduce gastric pH in
weaned pigs, aiding digestion.

Read more: Learn how to
optimize pig gut health, www.
WATTAgNet.com/articles/19946

Protein indigestion in the
young pig not only reduces efficiency of feed utilization but it
also gives rise to intestinal microflora populations that thrive on
protein, especially to opportunistic pathogens such as Escherichia
coli. This situation usually ends
with the development of diarrheas, and occasionally death, unless
pigs are treated with antimicrobial agents (antibiotics, zinc oxide, copper sulfate, organic acids,
phytogenics, etc.) that control intestinal pathogens. Thus, in many
cases, enhancing protein digestion
eliminates the need for expensive
medications and prevents the outbreak of costly diseases. In most
commercial farms, however, feed
digestibility is ignored when diarrhea problems are encountered.

Prevent protein indigestion
To prevent protein indigestion
in newly weaned pigs, several

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Table of Contents for the Digital Edition of Pig International - November 2017