An Enzyme-Microbial Feed Product for Large Framed Finishing Steers

Burt Weichenthal, Ivan Rush, Brad Van Pelt
University of Nebraska Panhandle Research Center

Summary...

Feeding MSE (multiple stabilized enzymes in an enzyme-microbial feed product) at the rate of 2 lb of product per ton of diet dry matter resulted in numerical increases in average daily gain and feed conversion that were not statistically different from those produced by the feeding of Rumensin and Tylan at 29 and 10 grams per ton of diet dry matter, respectively. Means for carcass measurements were similar for the two treatments. Percentages of liver abscesses were 13.2 and 11.3% for Rumensin-Tylan and MSE, respectively for the 139 day finishing trial in which the only source of roughage in the final diet was in the corn silage fed at 10% of diet dry matter, resulting in diet NEg at .65 Mcal per pound.

Introduction

The 1996 Nebraska Beef Report (pp. 68-69) included results from a finishing trial with British crossbred yearling steers in which Rumensin-Tylan was compared to MSE, a feed product containing multiple stabilized enzymes plus four strains of bacteria (three Lactobacillus cultures and one of Bacillus subtilis), three strains of yeast (Saccharomyces cerevisiae), and three strains of fungi (two of Aspergillus oryzae and one of Aspergillus niger). Steers fed MSE gained about 10% faster and 7.5% more efficiently than those fed Rumensin-Tylan at 29 and 10 grams, respectively, per ton of diet dry matter. Liver abscesses were not a problem with either treatment. These results suggested that Rumensin-Tylan could be replaced by MSE, especially in situations like the production of organic beef without the use of antibiotics. A second trial was initiated to test the same comparison with large-framed yearling steers and a similar diet except for replacement of 35% of the corn dry matter with ground, ensiled high-moisture corn.

Procedure

Charolais crossbred yearling steers were purchased in the spring for allotment to 12 pens of 9 head each for 6 pens on each of two treatments: (1) Rumensin fed at 29 grams and Tylan at 10 grams per ton of diet dry matter, and (2) the enzyme-microbial feed product MSE fed at two pounds per ton of diet dry matter. Three step-up diets were used to reach the final diet which on a dry matter basis included 53.64% dry rolled corn, 28.86% high-moisture corn, 10.05% corn silage and 7.45% protein-mineral-vitamin supplement that included NPN and natural protein to provide 58% crude protein. Calculated nutrient contents of the diet dry matter were about 12.5% crude protein, .65 Mcal NEg per lb, .77% calcium and .34% phosphorus.

The MSE was premixed at the rate of two pounds of MSE with eight pounds of finely ground corn so that ten pounds of premix were added to the mixer truck after all other ingredients had been added. During the first 72 hours on feed, MSE was fed at six pounds of diet dry matter (three times higher than the long-term feeding rate). Rumensin was fed at 25 grams per ton of diet dry matter during the first three days, at 28 grams during the feeding of the next step-up diet, and at 29 grams thereafter. A pelleted protein supplement with and without Rumensin-Tylan was used in the study.

The steers were not implanted. They were purchased from two sources and were large-framed, yearling Charolais crossbred steers that weighed about 812 pounds at the start of the trial on February 22, 1996. The steers were fed once a day at levels that would allow them to clean up most of the feed before the next feeding. The steers were slaughtered after 139 days on feed and carcasses were evaluated for dressing percentage, fat thickness, marbling, quality grade, rib eye area and yield grade.

One steer died during the test and one bull was removed. Carcass measurements could not be taken on a few carcasses per treatment because of a mix-up at the packing plant, but hot carcass weights were available on 51 carcasses per treatment as were measurements for fat thickness and rib eye area on 48 carcasses per treatment. Final weights and daily gains were calculated for 51 steers per treatment by dividing hot carcass weights by a common dressing percentage (62). Daily gains and carcass measurements for individual steers were analyzed by using the general linear model in SAS. Feed intake and feed conversion means were analyzed by SAS with pen as the experimental unit.

Results

Average daily gains for Rumensin-Tylan and MSE treatments, respectively, were 4.04 and 4.19 lb at 84 days, and 3.41 and 3.54 lb at 139 days after calculating final weights by dividing hot carcass weights by a common dressing percentage (62). Means for dry matter intake were similar for both treatments but varied somewhat within treatments during the study (Figure 1). A power outage during hot weather at 84 days caused the cattle to be without water, reducing feed intake, but both treatment groups came back on full feed in a few days. Final feed to gain ratios were 6.41 and 6.19 for Rumensin-Tylan and MSE, respectively, resulting in a difference not large enough to be statistically significant.

Means for carcass measurements were similar between treatments. Numerical differences in hot carcass weight, dressing percent marbling score and yield grade, were not statistically significant. Rib eye area was significantly larger (P < .06) with MSE, but rib eye area per cwt of carcass was the same. Percentages of liver abscesses were 13.2 and 11.3% for Rumensin-Tylan and MSE, respectively, which were not excessive or unusual for a high grain diet in which the only roughage component was in the corn silage fed at 10% of diet dry matter. Feeding these cattle once a day may be a factor that spreads the intake over longer periods of time, reducing acidosis and associated liver abscess problems that can occur.

Since the 1995 and 1996 trials were nearly identical and overall daily gains were in the same range in both trials, results were pooled (Table 2) for statistical analysis. Pooled means for final weight (adjusted to a 62% carcass dress), hot carcass weight, daily gain, feed conversion were significantly improved (P at or < .1) by MSE, and dressing percent was significantly higher for MSE (P < .05). The mechanism for this response from a multiple component, enzyme-microbial product remains to be defined, but improved feed utilization is suggested.

Cost of diet and cost of gain comparisons are shown in Tables A through I, for corn prices of $2.50, $3.00 and $3.50 per bushel. While the local price exceeded $4.00 per bushel during the summer of 1996, the price of $2.50 per bushel would be closer to an average price for recent years, and would be the best choice of these prices to compare treatment effects on cost of gain. While these two trials can give an indication of cost of gain differences, the cattle feeding industry will need to examine their own close-outs for comparisons of these products with their feed, conditions, and cattle.

Sections J through L involve example close-outs with corn at $2.50 or $3.00 per bushel for 1996 data (K) and for 1995 and 1996 pooled data (L). Naturally the profit per head decreases as the corn price goes up, but the increase in profit per head for MSE is the same for either corn price. The big question that affects profit per head is what are the average improvements in gain and feed efficiency for MSE from all of the similar finishing trials that have been done. If the average improvements are close to those observed in our 1996 trial, profit could be improved by $10.00 per head.