Quintana Méndez, Beatriz A.

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    Evaluación de una fuente de a-amilasa y proteasa sobre el consumo y la digestibilidad de nutrientes de las dietas y parámetros fisiológicos en ovinos
    (2015) Quintana Méndez, Beatriz A.; Rodríguez Carías, Abner A.; College of Agricultural Sciences; Fernández Van Cleve, John; Randel Folling, Paul F.; Solórzano, Luis C.; Latorre Acevedo, José R.; Department of Animal Science; Gregory Crespo, Alexandra
    The effects of adding a commercial source of α-amylase, an experimental protease or their combination on dry matter and nutrient intake and digestibility and several blood parameters were determined in lambs fed a basal diet of 34% ground corn, 40% tropical grass hay, and 26% soybean meal providing 21% dietary starch. Twelve crossbred lambs (22 kg) were assigned to one of four diets: no additive control (1) or diets containing α-amylase (2), protease (3), or their combination (4). Diets (DM basis) were offered daily at 4% of animal BW in four 28-day experimental periods consisting of 21 d of adaptation to the diet followed by 7 d of complete fecal collection. In each period, feed offered, orts, and feces were collected, quantified, and analyzed for DM, starch, CP, and NDF contents to determine intake and digestibility. Blood samples were collected from individual lamb at the end of each experimental period to determine glucose, BHB, NEFA, and insulin concentrations. Data were analyzed according to a 4 x 4 Latin Square experimental design. Treatments contrasts were performed using least squares means adjustment for multiple comparisons (Tukey-Kramer) between diets as follows: enzymes (2, 3 and 4) versus no enzymes (1), amylase (2 and 4) versus no amylase (1 and 3) and protease (3 y 4) versus no protease (1 and 2). In additional research the structural changes of hydrated corn grain treated or not with the enzymes were observed after 0, 6 and 24 hours using a scanning electronic microscope. In the feeding trial, DM intake was similar across treatments (1106, 1088, 1105 and 1088 g/d for control, and diets containing α-amylase, experimental protease or their combination, respectively). Adding protease to the diet decreased (P<0.05) starch consumption (248 vs. 255 g/d) and increased, but not significantly, NDF digestibility (48.6 vs 46.8%) as compared to that of lambs fed without the experimental enzyme. Adding enzymes to the diet tended (P<0.10) to decrease blood BHB concentration below the control level (4.26 vs. 4.68 mg/dL). Blood NEFA concentration tended to increase (P<0.10) in lambs fed α-amylase compared to those fed without α-amylase (0.17 vs. 0.14 mEq/L). Insulin level tended (P<0.10) to increase in lambs fed protease versus lambs not receiving the enzyme (80.3 vs. 71.8 pmol/L). Glucose level was similar for all experimental treatments. Both exogenous enzymes influenced blood metabolites, however a greater effect was observed in lambs fed the protease. Under electron microscopic examination structural changes in the starch-protein matrix and in the starch granule in hydrated corn grain treated with the exogenous enzymes were observed. Starch agglutination and zeina degradation occurred progressively due to enzyme activity.