at Midwest Section of American Society of Animal Science,
Practical Lessons in Feeding Bison Bulls for Meat
Dr. Vern Anderson and Bryan
Bison bulls fed for meat will consume a wide variety of feeds with some subtle differences observed in intake and performance. Bulls gained faster on higher energy feeds with lower cost per pound of gain even though higher energy feeds were more expensive per ton. There was extreme variation in animal performance due to season of the year, regardless of the diet. During winter, intake generally declined and gains were severely affected. Animal performance was similar during the other seasons of the year. Some differences due to previous diet and animal age may affect performance. From a practical perspective, it may be most cost effective to feed bison bulls only hay or very limited amounts of concentrate feeds during the winter and offer high grain diets during other seasons of the year. Feed delivery system had little effect on intake or gain in this study. This on-farm feeding study yielded valuable information bison growers can use to reduce costs of feeding bison bulls for meat.
Three bison feeding trials were conducted using a 4 x 4 Latin Square design with approximately 80-day feeding periods and 20 bison bulls per cell. Objectives of the respective trials were to 1) evaluate alternative feeds, 2) compare effects of energy level, corn type, and grain processing, and 3) study feed delivery methods for bison bulls fed for meat. Effects of season on feedlot performance were evaluated in experiment 1 and 2. In Exp. 1, bison bulls (avg. initial wt. 471 lbs.) consumed equal (P>.10) amounts of concentrate diets (69% of DMI) formulated with wheat midds, wheat screenings, crambe meal or a proprietary commercial formulation. Daily gains from screening diets (1.72 lbs.) were greater (P<.10) than crambe meal (1.52 lbs.) with the other diets intermediate (1.61 lbs.). DM intake as a percent of body weight was not affected by season (P>.10) but daily gains were reduced (P<.10) during winter (.37 lb.) compared to the other three seasons (1.63 lbs.). In Exp. 2, treatment diets were wheat screenings, rolled corn, rolled waxy corn, or whole waxy corn with grass hay offered free choice. Bison bulls (avg. initial wt. 602 lbs.) gained fastest (P<.10) on the rolled corn diets (1.65 lbs.), followed by the whole corn diet (1.45 lbs.), and wheat screenings (1.43 lbs.). DM intake was similar (P>.10) for all treatments (69% concentrate). Daily gains during the winter (.99 lb.) were less (P<.10) than the other three seasons (1.72 lbs.). In Exp. 3, four feed delivery systems were compared (avg. initial wt. of bison bulls, 653 lbs.). The same concentrate (wheat screenings pellets) was fed in a self feeder; in fenceline bunks; or in a programmable feeder. The fourth treatment was chopped hay and concentrate fed as a TMR in a fenceline bunk. Concentrate and dry matter intake was greater (P<.10) for the TMR diet. Hay intake was greater and concentrated less (P<.10) for the self feeder. No differences (P>.10) in gain or feed efficiency were observed. Bison gains were modest throughout these trials but appear to be influenced by diet or feed delivery system.
Key words: Bison, Feeds, Energy, Feed Delivery, Season
Bison production is increasing in the Northern Plains states and provinces due to producers’ individual efforts and the organization of a cooperative to process and market bison meat. Bison are native ruminants that roamed the prairie regions prior to settlement by man. They are highly adapted to the region’s climate and plant communities. Privately owned bison cow herds are currently managed for commercial production using modern grazing practices developed for beef. Bison bulls not selected for breeding are harvested for meat. However, feeding bison bulls for meat poses unique challenges due to several behavioral factors that are specific to the species. Few commercial feedyards feed bison. Most producers feed their own bulls using anecdotal information and trial and error practices. Little is known about the nutrient requirements of bison and optimum bison feeding systems. A formal bison research program is being developed at the North Dakota State University Carrington Research Extension Center to provide both basic and practical information to bison producers throughout the continent. In the meantime, practical feeding studies are being conducted with cooperating bison producers. Three studies reported here focus on alternative feeds, energy levels, corn type and processing, and feed delivery systems for bison bulls fed for meat.
Materials and Methods
Three on-farm bison feeding trials were conducted at the Double MM Bison Ranch, Carrington ND, in successive years starting in 1994. The trials were conducted using a 4 x 4 Latin Square experimental design. Approximately 80-day feeding periods closely associated with season were used in Experiments 1 and 2. There were approximately 20 bison bulls assigned per pen. Bulls were managed together for at least 60 days prior to the start of each trial. Bison were weighed at the start of each trial and assigned to initial treatment/pen by order through the chute. Pens were identical in size (50 x 100 ft), fence construction, waterer type and orientation, drainage pattern, and wind protection. At the end of each feeding period, bison were weighed and moved to a new treatment/pen based on pre-planned random assignment. Feed consumption and gains were summarized for each period.
Four different diets were compared to study alternative feeds in manufactured pelleted bison rations (Anderson and Miller, 1995). The treatments were based on unique ingredients in the diets. The diets were described as: 1) wheat screenings; 2) wheat middlings (mill run); 3) crambe meal; and 4) a proprietary commercial bison diet. Diet formulation and nutrient analysis of the diets is presented in Tables 1 and 2. The pelleted diets were offered in self feeders and big round bales of long stemmed grass hay placed in ring feeders. Bison bulls (avg. wt. 470 lbs. ± 29.5) were placed on trial February 15, 1994.
Energy level, corn type, and corn processing were evaluated using four different diets (Table 3). Treatments were: 1) 85% wheat screenings with 15% corn pelleted as an homogenous product (Screenings); 2) 75% rolled dent corn and 25% pelleted screenings supplement (RolledDent); 3) 75% rolled waxy corn and 25% pelleted screenings supplement (RolledWxy); and 4) 75% whole waxy corn and 25% pelleted screenings supplement (WholeWxy). Bison bulls (avg. wt. 604 ± 15.6 lbs.) were placed on trial June 21, 1995.
Treatments were methods of delivering feed to bison bulls (avg. wt 653 ± 172 lbs.) fed for meat. They were: 1) totally mixed ration (TMR) (75% pelleted concentrate and 25 % chopped grass hay fed once daily to appetite in a fenceline bunk; 2) separate feeding of pelleted concentrate (fed daily to appetite in a fenceline bunk) and grass hay (SEP); 3) pelleted concentrate fed in an automatic feeder (AUTO) with grass hay available, and 4) pelleted concentrate offered free choice in a self feeder (SELF) with grass hay available. The self feeder was a conventional calf creep feeder mounted on wheels. The pelleted concentrate was formulated using 75%wheat screenings, 15% corn grain, 5% dried molasses and 5% salt and mineral supplement. The commercially manufactured pelleted bison ration averaged 90.32% dry matter, 14.96% crude protein, 15.24% ADF and 28.67% NDF, and 8.17% ash. Long stemmed grass hay (89.16% dry matter, 7.55% protein, 43.02% ADF, 72.63% NDF, and 9.58% ash) was fed as large round bales in ring feeders. The trial started August 6, 1996 and animals were rotated to a new feeding system in a pre-planned random order every 49 days.
The TMR and SEP animals were fed to appetite based on daily bunk readings. The AUTO feed was delivered 5 times daily to a bunk placed under the discharge spouts. The “Chuck Wagon” feeder was manufactured by Sheyenne Advanced Feeding Systems, Cooperstown, ND.
Data were analyzed using general linear model procedures according to SAS (SAS, 1988). Pen was the experimental unit and period the replicate for dietary comparison. In Experiment 1, diet treatments were initially compared using all four periods (seasons). Significant effects of winter (P<.01) suggest more sensitive dietary comparisons may be made using only spring, summer and fall periods. Granted that winter-feeding is important for evaluation of rations, in this study, variation caused by decreased winter gains and differential feed intake suggested a second comparison. All periods were used as replicates in Experiments 2 and 3. In Experiments 1 and 2, data were pooled across dietary treatments to compare effects of season.
Dietary comparisons indicate intake of pelleted feed, hay, and total dry matter was not affected by diet treatment (P>.10) within the range of this study (Table 4). Average daily gain for bison fed the wheat screenings diet was higher (P=.07) than for bison consuming the crambe meal diet with the other two treatments intermediate.
In comparing effects of season, daily gains averaged 1.72 lbs. during spring, 1.39 lbs. during summer, 1.76 lbs. during fall, and .37 lb. during the winter ± .24 lb. Winter gains were lower (P<.01) than the other seasons (Table 5) and feed per unit gain was severely affected. Dry matter intake per unit body weight was not affected by season (P>.10).
In dietary evaluations (Table 6), hay intake was higher (P<.05) for Screenings than RolledWxy and WholeWxy with RolledDent intermediate. Total DM intake was similar for all treatments. While not significant (P>.10), DM/Gain was 27% more efficient for the rolled corn diets compared to the Screenings treatment. Gains increased numerically (23%) but not to a significant level (P>.10) with 75% rolled corn in the diet. The sensitivity of this experimental design may be questioned but trends are useful in early work with bison.
Differences (P<.05) were observed due to season with improved performance during summer and fall vs. winter and spring. (Table 7). Dry matter intake expressed as percent of bodyweight was greater (P<.05) for summer and fall vs. winter and spring (2.91 and 2.74 vs. 1.84 and 1.76, respectively). Average daily gains were greater (P<.05) during the summer and fall (1.85 and 1.94 lb/hd/day) vs. winter (.99 lb/hd/day) with spring gains intermediate. Dry matter intake was reduced during the winter and spring enough to offset the reduced gains and render feed efficiency similar (P<.05) over all periods.
The results of this study (Table 8) suggest feeding system may have some impact on the feed intake but limited effect on the performance of bison. Average dry matter intake was less (P<.05) for TMR at 24.26 lb/hd/day compared to the other three treatments averaging 26.9 lbs. This may be due to differences in hay intake as the TMR diet was consumed with virtually no waste while the ring feeders had more waste. The TMR hay level was established at 25% of the ration as fed. This is less hay intake than occurred in the other three treatments with free choice hay. No estimate of hay consumption vs. waste was made in this study but hay placed in the feeders average 13.27 lb/hd/day vs. 6.79 consumed in the TMR (P<.05). Animals compensated for the apparent increased hay intake by reducing (P<.05) pelleted concentrate intake in the three diets with free choice hay. Comparing the three free choice hay treatments, pelleted concentrate intake was lowest (P<.10) for the SELF (15.83 lb/hd/day) and highest for the SEP (17.64 lb) with intermediate intake in the AUTO (17.00) treatment.
Estimated dry matter intake was 2.65 lbs. less for the TMR vs. the other three diets (P<.05). A higher proportion of hay should possibly have been used in the TMR for equivalent ingredient intake. The higher concentrate level in the TMR (P<.05) would be expected to produce improved daily gains, which it did not.
The TMR and SEP treatments yielded gains of 1.39 and 1.37 lb/hd/day compared to 1.50 for both AUTO and SELF during the 195-day trial. Individual treatment means for gains were not different (P>.10), nor were pooled means for bunk feeding (TMR and SEP) vs. self-feeding systems (AUTO and SELF).
Bison exposed to the AUTO feeder became conditioned to the sound of the auger motor, and readily came to eat when it started. However, the natural tendency of delivery system worked well throughout the feeding trial and proved to be a convenient method of delivering a concentrate. The self-feeder was a conventional rectangular calf creep feeder accessible from both sides.
Bison feeders currently prefer to use large amounts of the relatively inexpensive high fiber feeds, such as wheat screenings, prior to the inclusion of other feeds in the ration. Bison digest high fiber feeds more thoroughly than cattle (DeLiberto, 1995). However, in Experiment 2 and a Colorado study, bison gained faster and more economically using higher energy diets (70 and 90% concentrate vs. 30 and 50% concentrate) (Stanton et al., 1996). The modest energy levels in many commercial bison diets may limit growth rate and feed efficiency, and increase cost of gain. Higher energy diets are recommended.
Lower feed intake and gains, and reduced activity have been observed in bison during colder, darker months (Christopherson, et al., 1979). Reduced activity is probably an effort to conserve energy expenditure (Rutley, 1992) in sometimes futile or difficult searches for food under snow. Other studies support the theory of shortening day length impacting intake and gains in bison (Stanton et al., 1995) and cattle (Peters et al., 1980; Zinn et al., 1986a,b; and Tucker et al., 1984). Separating photoperiod and cold temperatures effects is difficult and may be a moot point as neither can be controlled. However, the cold tolerance of bison would suggest photoperiod may have a greater effect (Christopherson et al., 1979). In the wild, bison may respond to changing season by exhibiting preparatory increase in feed intake and compensatory feed intake with resulting faster growth in the spring and fall. Increased intake of hay during the winter may be an evolutionary response as a method of increasing body heat production. It also had the effect of reducing energy concentration of the ration.
More research is needed on photoperiod and/or cold effects in an effort to develop different feed management strategies, lighting techniques, diet manipulation, or other approaches to counter this phenomenon. The seasonal differences observed in these studies agree with reduced animal performance during the winter concluded by Rutley and Church, (1995) and Stanton et al., (1996). Bison feeders are challenged by the substantial seasonal effects on animal performance. Potential strategies to counter these effects include altering diet (revert to grass hay), manipulating the environment (supplemental light), and selection of herd sires for year round performance.
Feeds and feeding systems appear to have some impact on feed intake patterns but limited effect on performance of bison bulls. Economies of scale will dictate choice of feeding systems but small scale feeding of bison appears to be possible with self-feeders.
Although bison nutrition research is difficult to conduct due to the behavior patterns and unique social structure of bison, this growing industry is in great need of information applicable to feeding bison for meat.
is expressed to the following organizations for support of this project:
Dakota Agricultural Products Utilization Commission, North Dakota Waxy Corn
Growers, North Dakota Corn Council, G & R Feeds, and the North Dakota
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Table 1. Formulation of diets with alternative feeds fed to bison bulls
screenings are highly variable in composition.
Principle components are green and yellow foxtail seed (pigeon grass)
(50-80%), cracked wheat (10-20%) and other weed seeds.
a, b values with different
superscripts are significantly different, (P<.10)
a, b, c - values with different
superscripts are significantly different, (P<.10)
a, b - values with different
superscripts are significantly different, (P<.10)
a, b, c - values with different
superscripts are significantly different, (P<.05)