Rough Draft of Preliminary Report

INFLUENCE OF MULTIPLE STABILIZED ENZYMES (MSE) AND RUMENSIN/TYLAN WITH TWO LEVELS OF PROTEIN AND FIBER ON FINISHING FEEDLOT STEER PERFORMANCE

Dr. Dan D. Hinman and S.J. Sorensen

University of Idaho

INTRODUCTION

Multiple stabilized enzymes are used to stabilize the mico flora in the gut, especially in high grain diets. Previous research at the University of Idaho (1996) has shown a numerical increase in average daily gain, dry matter intake and feed efficiency over steers fed rumensin/tylan in a barley based diet. Work at University of Nebraska (1995) has shown the same type of results in steers fed a corn based diet. The work at University of Idaho has led to the theory that crude protein and acid detergent fiber levels may influence the response to multiple stabilized enzymes and rumensin/tylan.

The purpose of this research was to test that theory.

MATERIALS AND METHODS

Crossbred yearling beef steers (n=140) averaging 317 kg were randomly assigned to one of four treatments in a 2x2 factorial design feeding study. Seven pens of five animals were randomly assigned to each treatment. Treatments were: (1) control diet with Rumensin and Tylan (RT), with 13% CP and less than 9% ADF (RTHPLF); (2) treatment diet with multiple stabilized enzymes (MSE), with 13% CP and less than 9% ADF (MSEHPLF); (3) control diet with Rumensin and Tylan, with 11% CP and greater than 11% ADF (RTLPHF); (4) treatment diet with MSE, with 11% CP and greater than 11% ADF (MSELPHF). Diets were formulated to provide NRC recommended levels of nutrients for the age and type of cattle used. MSE was fed at the rate of 909 g per 908 kg DM (2 lb/ton) for the first 3 d then decreased to 454 g per 908 kg DM (1lb/ton) for the remainder of the trial. Rumensin was fed at the rate of 29 g/ton DM and Tylan at the rate of 10 g/ton DM. Rumensin and Tylan were mixed into the supplement for those diets while the MSE was top dressed by hand while the feed was mixing. Feed was made available at approximately 0800 and 1600 daily. Steers were branded, vaccinated, implanted (Ralgro), wormed and ear-tagged upon arrival and immediately placed on their respective diets starting with a 70% barley diet for 12 d followed by the finishing diet (84% temper rolled barley, 5% chopped alfalfa, 7% corn silage and 4% supplement, DM basis) for the remainder of the trial (Table 1). Beginning and final weights were taken with an overnight stand without water and given a 3% pencil shrink. Feed intake was recorded daily on a pen basis. Steers were weighed every 28 d and re-implanted on d 56 (Revalor). At the end of 129 d, 70 steers that were judged to grade choice were slaughtered and hot carcass weight, marbling, quality grade, ribeye area, backfat, and liver score were measured and kidney-pelvic-heart fat and yield grade were determined by USDA graders. On d 149, the remaining 70 steers were sent to slaughter and the same carcass data collected.

Analysis of variance was conducted using SAS with RT and MSE (ADD) and CP and ADF levels (SUPP) as the main effects and the ADD X SUPP interaction in the model. Individual animal data was pooled by pen for all measured parameters since feed intake data was only available on a pen basis. No interactions (P>.05) for carcass characteristics were detected, so the main effects are presented.

RESULTS AND DISCUSSION

Neither MSE nor RT influenced final weight (P>.05). Average daily gain was greater by 5% for MSE than RT (P<.05). Rumensin/Tylan had lower (P<.05) DMI than MSE. This finding was expected as it is well documented that RT causes a decrease in feed intake. Days on feed were shorter (P<.05) for MSE than RT (137 d vs. 141 d, respectively). Because of the greater rate of gain for the MSE steers, they finished faster than the RT but ate more feed doing so, thus they had a similar (P>.05) gain:feed (173 g/kg vs. 176 g/kg, respectively).

No influence (P>.05) from HPLF and LPHF diets were detected for final weight, ADG, or days on feed. Laboratory analysis of the mixed diets found the high CP diet to average 12.1% and the low CP diet 10.1% (Table 1). Dry matter intake was greater (P<.05) for HPLF diet than LPHF. The steers on the LPHF diet were more efficient (P<.05) in converting feed to gain than the HPLF. The NRC (1984) CP requirements for this type of steer start at 11% and drop to 9% as the cattle grow, thus the CP levels fed here may not have been limiting. The high fiber diet was 12.6% ADF while the low fiber was 12.5% ADF. There was a ADDxSUPP interaction for DMI and GF detected (P<.05).

The MSELPHF had the heaviest final weight (P<.05) with RTLPHF having the lightest (569 kg vs. 555 kg, respectively) with both HPLF diets being intermediate and similar (P>.05). The fastest gain occurred with MSELPHF at 1.69 kg/d while RTLPHF gained the slowest (P<.05). Dry matter intake was greater (P<.05) for MSEHPLF than the other diets. Feed efficiency was best (P<.05) for MSELPHF and least for MSEHPLF, with the RTHPLF and RTLPHF diets being intermediate and similar. Days on feed was not changed (P>.05) by any treatment.

Hot carcass weight, marbling, quality grade, ribeye, kidney-pelvic-heart fat (KPH), dressing percent and liver scores were not changed (P>.05) by either MSE or RT. Backfat and USDA yield grade were greater (P<.05) for MSE than RT. A trend (P=.06) for MSE to have heavier hot carcass weight than RT (346 kg vs. 340 kg, respectively) was noted. Protein and fiber levels did not alter (P>.05) any carcass characteristics. Marbling, quality grade, ribeye, KPH and liver score were not influenced (P>.05) by dietary treatment. The hot carcass weight of MSELPHF was greater (P<.05) than RTLPHF. Backfat for MSELPHF was greater (P<.05) than RTHPLF and RTLPHF. Yield grade was higher for (P<.05) MSELPHF than the RTLPHF diet. Dressing percent was greatest (P<.05) for RTLPHF and lowest for MSEHPLF.

IMPLICATIONS

In general, the multiple stabilized enzyme fed steers gained faster, ate more feed and were fatter at an earlier slaughter date than steers receiving rumensin/tylan. Higher protein and lower acid detergent fiber diets increased dry matter intake and decreased feed efficiency. While protein and fiber levels did not result in changes in carcass characteristics, multiple stabilized enzymes increased the carcass fat levels (as measured by backfat and yield grade) while increasing hot carcass weight over that of steers fed rumensin/tylan.