<p>Carbohydrases have been used to improve fiber utilization in
monogastric animals. However, their effects on animal performance and nutrient
digestibility have been inconsistent in pigs. The efficacy of carbohydrases has
been suggested to depend on enzyme activity and fiber composition, but recent
evidence suggests other factors like environmental conditions may play
significant role. The effect of heat stress (HS) on the efficacy of a multienzyme
carbohydrase blend in growing pigs was investigated. It was hypothesized that
HS alters the efficacy of carbohydrases. Ninety-six growing pigs (gilts:barrows;
1:1) (initial BW of 20.15±0.18 kg) were randomly assigned to 6 treatments, with
8 replicates of 2 pigs replicate pen in a 3×2 factorial arrangement: three
levels of carbohydrase (0, 1X or 2X) and two room temperature conditions (20<sup>o</sup>C
constant or cyclical 28<sup>o</sup>C night time and 35<sup>o</sup>C daytime). The
1X is the recommended commercial dose of the enzyme (50g/tonne) and provides
1250 visco-units endo-β-1,4-xylanase, 4600 units α-L-arabinofuranosidase and
860 visco-units endo-1,3(4)-β-glucanase per kg of feed. The 2X dose was
100g/tonne. Pigs were fed ad libitum for 28 days and 1 pig per pen was
sacrificed at d28. Heat stress increased
the respiratory rate and skin temperature (P<0.001). There was no enzyme × temperature
effect on response criteria. Enzyme treatment quadratically increased BW d28
(P=0.025), ADG (P=0.022) and average daily feed intake (ADFI) (P=0.032) with 1X
being the highest. Heat stress reduced the BW at d14 (P=0.002) and d28
(P=0.006), average daily gain (ADG) (P=0.005) and ADFI (P<0.001). However,
there was a trend of increased gain: feed ratio (G/F) (P=0.093) in the HS pigs
compared to the thermoneutral (TN). Heat stress increased apparent jejunal
digestibility (AJD) of energy (P=0.039) and apparent ileal digestibility (AID)
of calcium (P=0.007). ADFI was positively correlated to ADG (r=0.57;
P<0.001) but negatively correlated to G/F (r=-0.42; P=0.003). Enzyme
supplementation increased in vitro viscosity at 3, 4 and 5 hours (P value). Heat
stress reduced serum glucose concentration on d1 (P=0.0002) but increased serum
non esterified fatty acid (NEFA) concentration (P=0.002). A similar trend to
NEFA was observed in triacylglycride (TAG). In the jejunum, carbohydrases had
trend for increased villi height (P=0.07) while HS reduced villi height (P=0.02).
Heat stress increased the jejunal mRNA abundance of IL1β in the jejunum
(P<0.001). There was a trend for a reduction in ileal MUC2 (P=0.092),
occludin (P=0.091) due to HS, with the trend increasing in PEPT1 (P=0.064). There
was no effect of HS on alpha diversity of fecal microbiome, but sampling day
affected beta diversity. There was an increase in the abundance of pathogenic
bacteria (like Clostridium) in the HS group. Heat stress did not alter the
efficacy of carbohydrase but both carbohydrase and HS modulate pig performance
independently.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/13368824 |
| Date | 11 December 2020 |
| Creators | Paul Oluwakayod Oladele (9761987) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Effect_of_heat_stress_on_the_efficacy_of_a_carbohydrase_admixture_in_growing_pigs_fed_wheat-based_diets/13368824 |
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