Short communication
The effect of an exogenous enzyme treatment
on production and carcass characteristics of
growing and ®nishing steers
D.R. ZoBell
a,*, R.D. Wiedmeier
a, K.C. Olson
a, R. Treacher
baDepartment of Animal, Dairy and Veterinary Science, Utah State University, Logan, UT 84322-4815, USA bFinnfeeds International, Marlborough, Wiltshire SN8 1AA, UK
Received 5 October 1999; received in revised form 15 February 2000; accepted 16 August 2000
Abstract
A study was conducted to determine the effect of an exogenous enzyme treatment on various production and carcass characteristics of growing and ®nishing steers. In the 84-day growing trial, 32 primarily British crossbred individually fed steers (259 kg BW) were randomly assigned control
(C) or enzyme (E) treated diets (n16 for C and E). The diet contained 65:35 (DM basis)
forage:concentrate. Steers on the enzyme treated diet received a total mixed ration (TMR) that contained a solution with endoglucanase and xylanase activity at a rate of 5580 and 15,880 IU/kg of TMR DM, respectively. Average daily gain (ADG), dry matter intake (DMI) and feed ef®ciency
(FE) were not affected by treatment (P>0:05), although FE showed a trend for improvement
during the ®rst 28 days for the enzyme treatment (P0:063). The ®nishing trial consisted of 20
individually fed steers (409 kg BW) randomly assigned treatment (n10 for C and E) in an 84-day
trial. Steers on the enzyme treated diet received the same enzyme solution and level as in the growing trial. The ®nishing ration consisted of a 20:80 forage:concentrate ratio (DM basis). Results
indicated no difference (P>0:05) for ADG, DMI or FE as well as various carcass traits including
hot carcass weight, ribeye area, backfat, yield, quality grade or cutability. It is concluded from these growing and ®nishing trials that the enzyme concentrate used did not affect production or carcass characteristics, but may be bene®cial for improving feed ef®ciency when cattle are ®rst placed on
feed.#2000 Elsevier Science B.V. All rights reserved.
Keywords:Enzyme; Steers; Growing; Finishing
87 (2000) 279±285
*Corresponding author. Tel.:1-435-7972-144; fax:1-435-7972-118.
E-mail address: dalez@ext.usu.edu (D.R. ZoBell).
1. Introduction
In beef feedlot production, feed can make up to 75% of the cost of gain. Enzyme research and use has expanded into ruminant nutrition and recent improvements in manufacturing technology have decreased the cost of enzyme preparations for the feed industry. This may eventually produce products that could lower the cost of gain for growing and ®nishing cattle.
In recent years, newer enzyme preparations have been used in ruminant diets, at varying levels, on a broad range of forages, concentrates, and enzyme preparations (Beauchemin et al., 1997; Lewis et al., 1996; Feng et al., 1996) with varying results. Other studies (McAllister et al., 1999; Pritchard et al., 1996) using enzyme preparations on barley silage and alfalfa silage-based diets have demonstrated increased ®nal weight and ADG of feedlot cattle. These recent studies suggest that enzyme formulations that are being developed can in¯uence ruminant digestibility and subsequent production.
The objective of this study was to determine the effect of a commercially prepared exogenous enzyme solution on production and carcass characteristics in growing and ®nishing steers using grass and alfalfa hay, corn silage and barley grain.
2. Materials and methods
The growing phase consisted of 32 individually penned British crossbred steers (259 kg BW) randomly assigned to treatments: control (C), or enzyme (E). All steers were allowed to adapt to their respective diets for a 2-week period prior to start of the trial. The growing ration consisted of 65:35 forage:concentrate (Tables 1 and 2) and was fed as a total-mixed ration (TMR). All feedstuffs were analyzed initially for dry matter and nutrient levels and silage dry matter obtained weekly. Nutrient analysis was conducted using standard procedures (Association of Of®cial Analytical Chemists, 1990). Feed was
Table 1
Growing and ®nishing diets used in enzyme feeding trialsa
Feedstuffb Growing (day) Finishing (day)
0±28 28±84 0±84
Alfalfa hay 17.5 21.8 7.0
Grass hay 17.9 5.6 0
Corn silage 26.3 30.8 10.0
Barley grain 35.2 38.4 78.2
Feedlot supplement 3.2 3.3 4.8
aFeedstuffs are percent dry matter. Supplement consisted of 11.0% crude protein, 5.0% NaCl, 0.50% P, 8.0%
Ca, 0.24% Mg, 0.76% K, 200 ppm Cu, 400 ppm Mn, 650 ppm Zn, 2 ppm Se, 22 ppm I, 9 ppm Co, 121,000 IU/ kg Vitamin A, 37,400 IU/kg Vitamin D, 55 IU/kg Vitamin E and 360 ppm Rumensin. Formulated according to National Research Council (NRC, 1984) recommendations.
bAlfalfa and grass hay were chopped to 1 in. in length and corn silage to 1.5 in. and ensiled, and the barley
grain was coarse rolled.
mixed and delivered to the steers in a Rissler feed cart (Rissler Mfg, Mohnton, PA) which recorded amounts fed daily. All steers were fed once per day (9:00 A.M.) to appetite and feed bunks were read each afternoon and prior to morning feeding which was used to determine the amount of feed to deliver to each pen the following day.
The enzyme preparation used contained xylanase and endoglucanase (beta-glucanase) activity of 7940 and 2790 International Units (IU) per gram, respectively, as speci®ed by the manufacturer (Finnfeeds International, Marlborough, Wiltshire, UK). The xylanase activity was determined using oat spelts as the substrate at 0.6% w/v ®nal concentration with sodium acetate as the buffer, pH 5.3 and temperature 508C. Beta-glucanase activity was measured using barley beta-glucan as the substrate at 0.5% w/v ®nal concentration with the buffer sodium acetate, pH 5.0 and temperature 308C. The enzyme was diluted with water and provided 15,880 and 5580 IU/kg TMR DM of xylanase and endoglucanase, respectively. Dilution occurred prior to feeding and was added to the TMR as it was mixing.
All steers were weighed initially, every 28 days and at trial termination (day 84). Health records were kept but no animals required treatment during the trial.
The ®nishing trial consisted of 20 crossbred individually penned British steers (409 kg BW). All steers were from the growing trial and were assigned to treatment, control (C) or enzyme (E), in such a manner as to randomize treatment. Steers were adapted to their diet (20:80 forage:concentrate DM basis), over a 1-month period prior to start of trial (Tables 1 and 2) and received no enzyme during this period. Feedlot supplement was the same used as in the growing trial and all steers were weighed and implanted at initiation of the trial. Enzyme treatment was the same as the growing trial at 2 ml of concentrate per kg of TMR DM. Enzyme was added to the TMR as in the growing trial. Animal health data were kept, with no animals receiving treatment through the 84-day trial.
The study was terminated based on live animal ultrasound backfat, longisimus dorsi, and marbling measurements using proprietary image analysis software (Brethour, 1991, 1992). Steers were slaughtered at the E.A. Miller Ltd. (Hyrum, UT) facility and carcasses graded after a 24 h chill.
Table 2
Nutrient speci®cations of growing and ®nishing rations used in growing and ®nishing enzyme feeding trialsa
All data were analyzed using the General Linear Model procedure of the Statistical Analysis System (SAS Institute Inc., Box 800 Cary, NC 27511). Least squares analysis of variance conducted using the GLM procedure of SAS was employed to detect treatment differences and derive least squares means and standard errors for weights, dry matter intake (DMI), average daily gain (ADG), and feed ef®ciency (FE). The repeated measurements option was employed to compare responses across time. Carcass characteristics including backfat (BF), ribeye area (REA), kidney pelvic and heart fat (KPH), percent choice quality grade (CQG), cutability (CUT) and yield grade (YG) were analyzed by least squares analysis of variance. Treatment (control versus enzyme) was the only source of variation used in the analysis with steers nested within treatment as the error term.
3. Results and discussion
3.1. Experiment 1 Ð growing trial
There was no difference between treatments for ADG, DMI and FE (P>0:05) during any of the treatment periods, although FE tended to be higher in the initial 28 days (P0:063) for the treated steers. Dry matter intake, ADG and FE remained relatively constant for both treatments throughout the trial with little variation among periods (Table 3).
Beauchemin et al. (1995) found that growing steers offered ad libitum barley silage supplemented with incremental levels of a commercially prepared xylanase and cellulase enzyme showed no response, although there was a response when cubed alfalfa and timothy hay were fed, depending on enzyme level. It was concluded that optimal levels of enzyme and results obtained depend upon the type of forage or the method of application.
Table 3
The effect of an exogenous enzyme on average daily gain (ADG), dry matter intake (DMI) and feed ef®ciency (FE) for growing steers
Period (day) Variable Treatment Overall meana
Control Enzyme
0±28 ADG1 (kg/day) 1.190.07 1.300.07 1.25
DMI1 (kg/day) 8.640.21 8.320.21 8.45
FE1 7.730.20 6.570.20 7.15
28±56 ADG2 (kg/day) 1.240.07 1.180.07 1.21
DMI2 (kg/day) 8.230.22 8.050.22 8.14
FE2 6.840.21 7.260.20 7.05
56±84 ADG3 (kg/day) 1.220.08 1.160.08 1.19
DMI3 (kg/day) 10.10.29 9.550.29 9.80
FE3 8.720.24 8.680.23 8.71
aAtP<0:05: ADG1ADG2ADG3; DMI16DMI26DMI3; FE1FE26FE3.
There were no studies found in the literature where a combination of corn silage and hay was fed to growing cattle to determine the effect of enzyme preparations on production. However, in a hay-based diet, Lewis et al. (1996) fed a 70:30 grass hay:barley diet (DM basis) to ®nishing steers to examine method of delivery of a solution containing cellulases and xylanases. They concluded that direct application of enzymes to forages is capable of improving forage digestion.
3.2. Experiment 2 Ð ®nishing trial
Dry matter intake, ADG and FE were not affected by treatment (P>0:0; Table 4) although DMI was lower for treated steers in the 0±28-day period (P0:046). However, this did not have an effect on FE for this or subsequent periods. Overall means for ADG, DMI and FE for each period are also shown in Table 4 indicating that ADG was decreased in period three and FE decreased as treatment progressed (P<0:05). This may be a result of a normal decline in FE at the end of the ®nishing period associated with fattening cattle.
No difference was detected in carcass traits between treatments (P>0:05; Table 5) for any of the traits. This would be expected as production variables were not affected by treatment.
ZoBell et al. (1998) supplemented an exogenous polysaccharide-degrading enzyme described as a beta-glucanase in a barley-based (coarsely rolled) ®nishing diet fed to yearling bulls intended for slaughter. Enzyme had no effect on growth performance (ADG and FE) or carcass characteristics. Beauchemin et al. (1997), however, found an 11% improvement in FE (P<0:05) in barley-based diets when an enzyme preparation with predominantly xylanase activity was fed to ®nishing steers. In the same study, there was no difference between treatments on production traits when this same enzyme preparation was used on corn-based diets or when an enzyme preparation was used containing high
Table 4
The effect of an exogenous enzyme on dry matter intake (DMI), average daily gain (ADG) and feed ef®ciency (FE) for ®nishing steersa
Period (day) Variable Treatment Overall meana
Control Enzyme
0±28 ADG1 (kg/day) 1.480.26 1.280.23 1.39
DMI1 (kg/day) 9.270.65 8.320.65 8.80
FE1 6.810.65 6.740.57 6.78
28±56 ADG2 (kg/day) 1.320.39 1.430.34 1.29
DMI2 (kg/day) 9.451.10 9.271.10 9.17
FE2 7.561.22 6.811.07 7.97
56±84 ADG3 (kg/day) 0.890.18 0.990.16 0.950
DMI3 (kg/day) 8.951.07 9.141.07 8.77
FE3 10.30.68 9.560.60 9.84
cellulase/low xylanase activity. In these studies, regardless of enzyme type or amounts, enzyme treatments had no effect on carcass characteristics.
It has been found that rate of passage and stability of exogenous enzymes differs among crude enzyme preparations and enzyme types (Hristov et al., 1998). Not all exogenous enzymes are equally effective at digesting substrates as indicated by research cited in this study. Enzyme activity must be described in studies because of the differences in commercial preparations and it is equally important to recognize that the substrate itself appears to have an in¯uence on the ef®cacy of exogenous enzymes.
4. Conclusions
Research on the use of exogenous enzyme preparations in beef cattle diets has produced an array of results. This is primarily because of the varied preparations and substrates used. The results from the growing and ®nishing trials of this study showed that there was no improvement in production or carcass traits from the enzyme preparation used. Further research needs to focus on the substrates themselves in combination with management practices which may also affect results. Time, rate, and method of enzyme application must also be reviewed. Commercial providers of exogenous enzymes must also provide information that will more speci®cally de®ne the enzyme preparations, particularly activity rates and enzyme types. Much more research is necessary before exogenous enzymes should be made available to commercial beef cattle producers.
Acknowledgements
The authors wish to thank the Utah Agricultural Experiment Station for the funding of this project, their South Farm staff for assistance in conducting the trial and Finnfeeds International for the enzyme product. Published as Utah Agricultural Experiment Station publication no. 7214.
Table 5
The effect of an exogenous enzyme on carcass characteristics of ®nishing steersa
Treatment Initial
Control 408.7 483.4 305.7 2.45 74.8 90 0.76 50.8 2.59 Enzyme 410.5 485.9 304.9 2.50 78.1 90 0.76 50.8 2.41 P 0.881 0.806 0.894 0.795 0.142 0.98 0.881 0.249 0.250
aKPH: kidney, heart and pelvic fat; REA: ribeye area; QG: quality grade percent choice; BF: backfat; Cut:
cutability; YG: yield grade.
bFinal live weight includes a 4.0% pencil shrink at time of slaughter.
References
Association of Of®cial Analytical Chemists, 1990. Of®cial Methods of Analysis, 15th Edition. AOAC, Arlington, VA.
Beauchemin, K.A., Rode, L.M., Sewalt, V.J.H., 1995. Fibrolytic enzymes increase ®ber digestibility and growth rate of steers fed dry forages. Can. J. Anim. Sci. 75, 641±644.
Beauchemin, K.A., Jones, S.D.M., Rode, L.M., Sewalt, V.J.H., 1997. Effects of ®brolytic enzymes in corn or barley diets on performance and carcass characteristics of feedlot cattle. Can. J. Anim. Sci. 77, 645±653. Brethour, J.R., 1991. Relationship of ultrasound-measured backfat to feedlot performance of beef steers. Kansas
State Agricultural Experimental Reports of Progress, 627, p. 1.
Brethour, J.R., 1992. The repeatability and accuracy of ultrasound in measuring backfat in cattle. J. Anim. Sci. 70, 1039±1044.
Feng, P., Hunt, C.W., Pritchard, G.T., Julien, W.E., 1996. Effect of enzyme preparations on in situ and in vitro degradation and in vivo digestive characteristics of mature cool-season grass forage in beef steers. J. Anim. Sci. 74, 1349±1357.
Hristov, A., McAllister, T.A., Cheng, K.-J., 1998. Stability of exogenous polysaccharide-degrading enzymes in the rumen. Anim. Feed Sci. Technol. 76 (1±2), 161±168.
Lewis, G.E., Hunt, C.W., Sanchez, W.K., Treacher, R., Pritchard, G.T., Feng, P., 1996. Effect of direct-fed ®brolytic enzymes on the digestive characteristics of a forage-based diet fed to beef steers. J. Anim. Sci. 74, 3020±3028.
McAllister, T.A., Oosting, S.J., Popp, J.D., Mir, Z., Yanke, L.J., Hristov, A.N., Treacher, R.J., Cheng, K.J., 1999. Effect of exogenous enzymes on digestibility of barley silage and growth performance of feedlot cattle. Can. J. Anim. Sci., in press.
National Research Council, 1984. Nutrient Requirements of Beef Cattle, 4th Edition. National Academy of Science, Washington, DC.
Pritchard, G., Hunt, C., Allen, A., Treacher, R., 1996. Effect of direct-fed ®brolytic enzymes on digestion and growth performance in beef cattle. J. Anim. Sci. 74 (1 (Suppl.)), 296.
ZoBell, D.R., McAllister, T.A., Hristov, A.N., Popp, J.D., Entz, T., Cook, R.B., 1998. The effect of including a
