The present study was divided into four experiments aiming to evaluate the effects of
different types and dietary levels of exogenous enzymes on feed intake, digestibility,
nitrogen and energy balance, feeding behavior and blood metabolites in sheep. The
experiments were conducted at the Federal University of Uberlândia in the Sheep and
Goat Research Center of the Capim Branco farm from February to May 2017. The
treatments consisted of a control diet and four inclusion levels of enzymes (0.5; 1.0;
1.5 and 2.0%). The commercial products evaluated were AMAIZETM (amylolytic
enzyme), FIBROZYME® (fibrolytic enzyme), ALLZYME® SSF (enzyme complex), and
a MIX of these three products in equal proportions. All animals were housed in
individual metabolic cages for sixty days. All experiments were conducted using a Latin
square design (5x5), with five treatments and five replicates. The dietary inclusion of
the amylolytic enzyme (AMAIZETM) was evaluated in experiment I. Five ewe lambs
with a mean initial body weight of 54.04 ± 4.5 kg and aged eight months were used.
There was a significant difference for apparent digestibility coefficient of dry matter,
organic matter, total carbohydrates, non-fibrous carbohydrates, total digestible
nutrients, and gross energy digestibility. Enzyme level had a quadratic effect on gross
energy digestibility, reaching its peak at 0.82% of enzyme inclusion. The same trend
was observed for dry matter digestibility. The remaining parameters were not
influenced by the dietary inclusion of the amylolytic enzyme. The dietary inclusion of
the fibrolytic enzyme (FIBROZYME®) was evaluated in experiment II. Five ewe lambs
with a mean initial body weight of 46.48 ± 5.60 kg and aged seven months were used.
Creatinine concentration decreased linearly by 0.22 mg/dL with each 0.5% addition of
enzyme, whereas the remaining parameters were not affected by the dietary inclusion
of the fibrolytic enzyme. The dietary inclusion of an enzyme complex composed of
pectinase, protease, phytase, beta-glucanase, xylanase, cellulase, and amylase
(ALLZYME® SSF) was evaluated in experiment III. Five ewe lambs with a mean initial
body weight of 61.16 ± 5.80 kg and aged eight months were used. There was a
significant difference for the blood metabolites albumin and aspartate
aminotransferase (AST), with linear reductions of 0.085 mg/dL and 8.9 IU/L with each
0.5% addition of the enzyme complex, respectively. However, the enzyme complex
was not effective in altering the feed intake and nutrient digestibility in lambs. The
dietary inclusion of an enzyme MIX composed of three commercial products at the
equal proportions ( AMAIZETM; FIBROZYME®; and ALLZYME® SSF) was
evaluated in experiment IV. Five male lambs with a mean initial body weight of 25.89
± 2.6 kg and aged four months were used. There was no significant difference for dry
matter intake as a percent of body weight (%BW-1) and metabolic weight (BW0.75).
There was no significant difference for apparent digestibility coefficient of dry matter
and fecal score. The fecal output weight (organic matter basis) differed significantly in
lambs fed different inclusion levels of the enzyme MIX. The water intake increased
linearly by 183 mL with each 0.5% addition of the enzyme MIX. The blood metabolites
glucose and aspartate aminotransferase reduced linearly with the inclusion of the enzyme MIX. Only the enzyme MIX and AMAIZETM products caused significant effects
on apparent digestibility and nutrient intake. Products capable of degrading specific
substrates such as starch or cellulose are necessary for enzymes to function properly
and to exert their lytic effects on the ruminoreticular environment, resulting in higher
ruminal degradation rates of nutrients and improved animal performance.
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