A series of experiments were conducted to investigate the effects of adding an exogenous proteolytic enzyme (EPE) on the growth performance of beef steers fed growing and finishing diets containing 30% dried distillers grains with solubles (DDGS; Exp. 1), and results corroborated by in vitro ruminal fermentation in continuous cultures (Exp. 2). In Exp. 1, 48 group-penned Angus crossbred steers were randomly assigned to 2 treatments (n = 6) in a completely randomized design: DDGS TMR (DT) without and with EPE (27 mg of azocasein hydrolyzed/min/kg DM TMR). The addition of EPE during the growing phase increased DMI (P = 0.02), but had no effects on final BW, BW change, ADG, and G:F. Adding EPE during the growing phase decreased NDF digestibility, whereas the digestibility of DM, CP, and ADF were not affected. There was a tendency for both ADG (P = 0.09) and final BW (P = 0.11) to increase during the finishing phase without affecting BW change and G:F. As opposed to the growing phase, EPE increased digestibility (P < 0.04) of DM, CP, NDF, and ADF. In Exp. 2, 4 dietary treatments were assessed in continuous cultures; non-DDGS TMR (NDT) or DT finishing beef steer diet was combined without or with EPE in a 2 × 2 factorial design. The DT was the same diet used as the finishing diet in Exp. 1, and dose rate of EPE was the same as Exp. 1. Feeding the DT increased total VFA concentration (P = 0.01) which corresponded with a decreased (P < 0.01) pH compared with the NDT diet (5.8 vs. 6.0) regardless of EPE supplementation. Supplementing EPE tended to increase (P = 0.07) the total VFA concentration in both diets, but only increased digestibility of DM, OM, and NDF when added to the DT diet (P < 0.05), leading to tendencies on TMR × enzyme interaction (P < 0.10). Addition of the EPE product assessed in this study resulted in positive responses in Exp. 1 and 2 when added to finishing beef steer diets, and thus it is clear that use of protease enzyme products may be more effective in high concentrate diets such as finishing beef steer diets containing DDGS.

Syftet med den föreliggande studien var att undersöka rollen av prestationsångest och ältande mellan dispositionell mindfulness och självskattad prestation. Det var totalt 53 idrottare (22 kvinnor, 31 män; Målder = 29.32, SD = 12.28 år) från 18 olika idrotter som deltog i studien. Studien var av kvantitativ longitudinell design (tre tillfällen under en fyra veckors period) där den oberoende variabeln, den beroende variabeln och två möjliga mediatorer undersöktes med hjälp av Athletic Mindfulness Questionnaire, Sport Performance Questionnaire, Sport Anxiety Scale-2, och Rumination Reflection Questionnaire. Resultaten visade ingen signifikant indirekt effekt av dispositionell mindfulness på självskattad prestation genom varken ältande eller prestationsångest. Resultaten indikerar att ältande och prestationsångest inte medierar förhållandet mellan dispositionell mindfulness och självskattad prestation i det undersökta urvalet. Det diskuteras att mindfulness ändrar förhållandet idrottaren har med ångesten istället för att sänka den upplevda nivån av ångest. Forskning om ältande som en mediator mellan mindfulness och prestation diskuteras som sällsynt, vilket kan göra kunskapen om förhållandet otillräckligt för att göra några bestämda uttalanden. Resultaten bör tolkas med försiktighet med tanke på att undersökningen gjordes på en heterogen grupp av idrottare med en subjektiv mått av prestation. Vidare forskning bör fokusera på en bestämd grupp och använda mer objektiva mått på prestation, samt använda ett idrottsspecifik instrument för att mäta ältande. Nyckelord: prestationsångest, dispositionell mindfulness, idrottsprestation, idrottare / The purpose of this study was to examine the role of sport-trait anxiety and rumination in the relationship between dispositional mindfulness and self-assessed performance. A total of 53 athletes (22 women, 31 men; Mage = 29.32, SD = 12.28 years) from 18 different sports participated. A quantitative longitudinal design (three-time measures within a four-week period) was conducted wherein the independent and dependent variables, as well as the two potential mediators were measured using Athletic Mindfulness Questionnaire, Sport Performance Questionnaire, Sport Anxiety Scale-2, and Rumination Reflection Questionnaire. The results showed no significant indirect effect of dispositional mindfulness on self-assessed performance through neither sporttrait anxiety nor rumination. These findings indicate that sport-trait anxiety and rumination do not mediate the relationship between dispositional mindfulness and self-assessed performance in the examined sample. Mindfulness is discussed as altering the athlete’s relationship with anxiety rather than lowering the perceived levels of anxiety. Since research on rumination as a mediator between mindfulness and performance is very scarce, the knowledge about the relationship might be insufficient to make any decisive statements. Findings are to be taken with caution given the heterogeneous sample of athletes considered and the use of a subjective measure of performance. Further research should focus on a more targeted group and use a more objective performance measure, as well as a sport-specific rumination scale. Keywords: sport-specific anxiety, dispositional mindfulness, athletic performance, athlete