The project will deliver enhanced feed efficiency in creep-fed calves through the use of exogenous enzymes that can improve fiber digestibility of soybean hulls (as an energy-dense ingredient). This will be accomplished by:
1) Identify specific enzyme additives that can be used to improve fiber digestibility of soybean hulls and other co-products used in creep rations.
2) Determine the optimum rates of each potential enzyme that can be applied to maximize feed utilization over a range of feeding conditions.
3) Determine the actual cost to benefit ratio and return on investment of using enzymes to improve soybean hulls utilization, which will provide beef producers with the information needed before adopting this technology.

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Executive Summary

Project Title: Use of exogenous enzymes to improve nutritive value of soybean hulls
Principal Investigator: Uchenna Anele, Animal Scientist, NDSU Carrington Research Extension Center, 663 Hwy. 281 NE, PO Box 219, Carrington, ND 58421-0219, 701-652-2951, uchenna.anele@ndsu.edu
Co-investigators: Chanda Engel, NDSU-CREC, Animal Science Research Specialist

Introduction:
Feed is the single largest variable input cost in any livestock enterprise and improvement in feed efficiency can be a significant multiplier. We hypothesize that feed efficiency of calves can be improved, resulting in reduced feed costs and manure handling by using exogenous enzymes. This can be accomplished through identifying specific exogenous enzymes that target fiber digestion in calves fed soybean hull-based creep feed.
We started out with 10 exogenous enzyme treatments (NSPase, ABM, DYX, AMA, CUL, Mix1, Mix2, Mix3, Mix4 and Mix5) which were evaluated in the laboratory using the in vitro gas technique. This approach allowed us to measure gas production and dry matter digestibility of the different enzyme treatments. Gas production reflects the generation of short-chain fatty acids and microbial mass which are utilized by the animal to meet their nutrient requirements. Higher gas volume was noted for NSPase, ABM and DYX treatments compared with the other enzymes. Enzyme treatments did not result in higher dry matter disappearance but NSPase and ABM treatments had numerically higher (3% or more) dry matter disappearance values compared with the control.
As a result, we selected NSPase and ABM treatments for further evaluation by using cannulated steers (in situ bag technique). Compared with the control (no enzyme), both NSPase and ABM resulted in higher effective dry matter digestibility at low, medium and high feeding levels. Differences in dry matter digestibility as a result of enzyme inclusion ranged from 4 to 9%. Additionally, enzyme treatments resulted in 32 and 29% increase in neutral detergent fiber digestibility for NSPase and ABM, respectively. Overall, these two (in vitro and in situ) techniques were utilized to identify an exogenous enzyme (NSPase) that can potentially increase dry matter and fiber digestibility of soybean hulls in a creep feed.
Results of the creep study showed that the exogenous enzyme had no effect on final body weight, average daily gain, G:F and dry matter digestibility. Differences in dry matter digestibility between the two treatments were similar to values observed with the cannulated steers. Dry matter intake was greater for the control treatment. Lower dry matter intake in calves supplemented with the enzyme treatment did not affect their performance as they have similar average daily gain with the control treatment. The lack of difference on the effect of pen nested within the treatments for final BW, average daily gain, and G:F was expected because of the small pen number used in this study. Moreover, inclusion of exogenous enzyme in the ration of creep-fed calves have the potential to increase profit, as calves on the enzyme treatment consumed less feed (˜ half a pound) without any significant difference in average daily gain..