Comparison of buffering capacity measures on feedstuffs and diets for piglets

Abstract

Buffering capacity (BC) of several
feeds and diets for pigs was evaluated by different
ways: initial pH (pHi), titratable acidity or alkalinity
(AT) and BC. For the experiment were used 32
samples of different ingredients, mineral supplement
mix and diets, classified as amino acids, mineral
supplements, cereals and its raw products, soybean
and its raw products, animal products, and complete
diets. PHi was measured in three solutions with 10
g sample diluted in 90 ml distilled deionized water,
in which one either chloridric acid, formic acid or
a commercial acidifier based in formic acid, were
used to reduce the pH just to 5.0, or NaOH, when
the pHi was lower than 5.0. AT was defined as the
overall acid or alkali amount required to change the
pH between the pHi and 5.0, and was expressed as
mEq/100 g sample dry matter. CT was calculated
by dividing the AT values by the whole pH range,
with the values obtained with each acid source
used as replicates of each sample. Results of each
measure were submitted to an ANOVA considering
the classifications. Linear correlation between the
pHi and BC was also evaluated. Minerals and amino
acids showed extreme higher and lower values in
all measures and were divided in subgroups. Diets
and products of soybean and cereal showed similar
pHi values, but were different by the other measures
(P<0,05). CT showed higher sensibility than AT.
PHi displayed inconsistent correlation with BC, and
was considered a not trustable estimate of that
physicochemical property.