Feed-Weigh Station as a Method of Grain-Finishing Bison (Bison bison) Bulls

Bruce D. Rutley and John S. Church

Abstract

A total of 58 bison bulls were finished for slaughter using modified dairy cattle feeding station technology (FWS) as a source for feed grains. Bison had comparable average daily grain intake (6.2, 6.6 ,4.5 ,7.32 kgd-1); average daily forage intake (5.4, 3.8, 3.5, 3.5 kgd-1); average daily gain (0.96, 0.83, 0.51, 1.03 kgd-1); and feed conversion ratios (12.2, 9.6,20.5, 10.5) to control groups (grain available in self-feeder SF) for 90 day winter feeding periods (between October and January) for 1993-1994 and 1994-1995, respectively.

Both total daily grain consumption and average daily gain were impacted negatively (p<0.05) when animals were either moved into the finishing group, removed from the group, and when it was required to replace the collar carrying the transponder.

Impact on grain consumption was limited to day of movement while average daily gain averaged weekly was impacted.

Bison consumed more of their daily grain intake (p<0.05) during the evening (16:30- 24:00) feeding period compared to morning (0:01 -8:30) while midday (8:30 -16:30) consumption was intermediate. Differences between morning and midday consumption were greater during winter trials compared to a summer feeding period.

FWS method was rejected as a method of finishing bison bulls to a target weight because of the negative impact that removal has on gain for resident bulls. However the FWS method is a powerful research tool, with the results having direct application to the SF method of finishing bison bulls.

Background

The plains bison has been farmed or ranched since before the turn of the century when the species was rescued from extinction (Roe 1970; Dary 1974). At one time, considerable interest was shown in the bison as a species to hybridize with cattle and Agriculture Canada conducted research from 1917 until abandoned in 1965 (Peters 1958, 1984).

A resurgence in interest to farm bison occurred coincidentally with:
1) bioenergetics, metabolism and digestion studies (Richmond et al 1977; Christopherson et al 1977 & 1978; Schaefer et al1978; Christopheron et al 1979a & b); 2) demand for lean red meat; and 3) a search for more suitable forms of northern agriculture. This renewed interest resulted in considerable growth within the Canadian bison industry - especially in the Peace Country. In 1985, three Peace River region commercial herds farmed less than 150 head compared to 54 producers ranching 8820 head (prior to calving) in 1992, while the Canadian bison herd increased to 18,400 by October 1992 (Rutley 1992c). It has been estimated (Hussey 1991) that if nothing limits industry expansion that the national herd will be 120,161 by the year 2000.

Industry development has occurred in absence of applied scientific research. Bison research within the park herds has been ecological and zoological in scope (McHugh 1958; Roe 1970; Meagher 1978; Telfer and Carins 1979; Reynolds et al 1982; Hawley 1987; Reynolds and Hawley 1987; Hawley 1989; Meagher 1989) and provides little suitable data for current specific industry development questions related to finishing market bulls. The techniques that have enabled the bison industry's expansion were developed on an individual, ad hoc basis and are described in publications of the American Bison Association (1993) and the National Buffalo Association (Dowling 1990).

Limited empirical data is available for the commercial bison producer finishing bison for slaughter, however the commercial bison industry has been routinely finishing bison for regional, national and international markets. Gain of feedlot finished bison bulls in the scientific literature is limited to: 0.64 kgd-1 and 0.50 kgd-1 for males and females, respectively (Peters 1958) and 0.748 kgd-1 (Koch et al. 1988). Hawley (1986) reported slaughter characteristics for 6- 2.5 year old bison steers, but not ADG during the 78 day finishing period. Expected gain and finishing rations have also been published in bison industry publications (Dowling 1990, American Bison Association 1993) and by Rutley (1992a ). Reports from scientific studies of grain finishing of bison bulls as practiced by the members of the Peace Country Bison Association (PCBA) do not appear in the literature.

Introduction

Recent developments in the marketing of bison meat has resulted in demand exceeding supply. These market developments have occurred coincidentally with forwarding young bulls to the prime meat market, grain finishing and utilization of the newly developed Canadian Bison Grading System (Rutley 1992b). Therefore, the need for research into finishing of bison bulls was identified as a priority of the PCBA.

One particular problem was that associated with target market weight. In 1992, hot carcass weight from bison bulls slaughtered at Dawson Creek ranged from 201 to 408 kg. This wide range of carcass weight was considered undesirable by regular buyers of bison meat. New requirements considered consistent carcass weight to be +/- 25 kg, with an expectation of +/- 12 kg in the near future.

Simply weighing bison frequently to determine body weight is not recommended. Rutley (1992, unpublished data) reported weight loss and lack of consistent gain in bulls that were returned to the pen after weighing and removal of pen mates. If frequent weighing is not considered an option and the need to know body weight is paramount, then an alternative method of weighing finish bulls is required. It was proposed that dairy cattle feeding station technology be modified to include a scale platform to be placed under the standing area. Once the bull entered the station, it would be standing on the scales and thus a weight could be assigned to the animal while it was feeding. In this manner, a daily weight could be obtained, along with the frequency of visits to the feed station and the grain consumed at each visit. Knowing the weight daily would enable separation of the bull(s) from penmates for slaughter to occur so that the probability of matching target carcass weight could be maximized.

The feeding station also would enable recording of the number of daily visits to the feed-weigh station (frequency), the time of the visit, and the amount of grain consumed at each visit, enabling investigation of circadian effects on daily grain consumption. Knowing what percentage of grain intake occurs at different times in the day may assist producers in the scheduling of their respective handling and feeding practices.

Research Organization and Objectives:

Implications on industry development were considered sufficient to warrant themodification of dairy cattle feeding station technology for the purpose of developing a bison bull feed-weigh station both as a method of feeding and as a research tool.

The goal of this research was to develop a bison feed-weigh station (FWS) that would automatically identify individuals, record time and amount of grain dispensed, and record body weight to fulfill three objectives:

A.

    1. Compare the feed-weigh station (FWS) to a self-feeder method (SF) for finishing bison bulls.
    2. Determine the effectiveness of the FWS of meeting a target weight so that the variation in subsequent slaughter weight was minimized.
    3. Calculate the differences in cost of production associated with each method. If differences are substantial, calculate the cost/benefit to the producer and to the industry and make recommendations.

B. Determine circadian grain consumption of bison

C. Investigate the effects of animal movement and related handling on the grain consumption of feedlot finished bison.  This document is organized into three sections which contain independent methods, results and discussion for each section:

    • Section One: The effects of animal movement and related handling on grain consumption of bison
    • Section Two: Circadian effects on the grain consumption of feedlot finished bison
    • Section Three: Comparison of a computerized feed-weigh station vs. self-feeder as a method of grain finishing bison
    • Section One: The effects of animal movement and related handling on grain consumption of bison

Methods:

Twenty bison bulls between 26 and 30 months of age and over 350 kg entered and exited the Bison Evaluation Unit at the Center for Agricultural Diversification at different dates between February 12, 1993 and May 28, 1993 (table 1) and were moved into the feed-weigh station (FWS) pen.

Table 1: Bull entry and exit dates in the FWS pen.

Animal ID Entry Date Exit Date
19 Apr 8 May 6
23 Apr 8 May 28
24 Feb 12 Apr 13
25 Feb 12 Feb 16
27 Apr 8 May 4
54 Feb 17 May 28
60 Feb 17 May 28
69 Feb 12 May 14
90 Feb 25 Mar 1
94 Feb 12 May 4
95 Feb 17 May 28
103 Feb 12 May 3
113 Feb 12 May 3
149 Feb 12 May 3
154 Feb 12 May 3
168 Feb 17 Mar 16
169 Feb 17 May 18
170 Feb 17 May 18
171 Feb 17 Apr 21
240 Apr 8 May 28


There was no pre-set condition for which animals entered or exited, as the pen was utilized:

  1. to test the use of the feed station by bison, and
  2. as a holding pen to accommodate animals during a "warm-up" period prior to entering a finishing pen.

The number of animals on a given day after there was animal movement, and the number of animals moved in or out of the pen on a given day in which there was animal movement is summarized in table 2.

Table 2: Number of bulls in FWS pen after animal movement and number of bulls moved on days in which there was animal movement.

# of Animals 8 7 14 15 14 13 17 16 15 11 7 5
Date 12
02
16
02
17
02
25
02
1
03
16
03
8
04
13
04
21
04
3
05
4
05
18
05
+/- = in/out + - + + - - + - - - - -
# of Animals
Moved
8 1 7 1 1 1 4 1 1 4 4 5

Prior to entry into the FWS pen, bulls were weighed and then held in the bison squeeze to accommodate placement of a collar carrying the transponder. Handling facilities consisted of a half-circle tub complete with three boxes, palpation cage and bison squeeze (Hi-Hog Farm and Ranch Equipment Ltd.). Body weight was collected from a Senstek D-2000 electronic scale placed under the first box.

The animals were fed a standard ration of rolled and blended oats and barley (1:1), good quality forage (fescue straw), cattle mineral and water. Grain was dispensed via the computerized FWS, forage was available from a tombstone style round bale feeder, mineral was available from a standard wooden cattle mineral feeder, and city water was available from waterers (hog style).

Bulls were housed in a large pen with packed sandstone shale for footing.

Dividers between the pens were wire fence with plywood hung as a visual barrier. No additional shelter was provided. The pen was located adjacent to the Canadian National spur line into Dawson Creek.

Upon entry into the feed station, bulls were required to step onto the scales. As they approached within 16 inches of the feed bin, a sensor read the signal from the transponder attached to the collar around the bull's neck. A signal was then sent via cable to the RationMaster © Computer Control Unit. The bull identification number, the amount of grain dispensed ( set at 0. 5 kg per minute ), and the time of entry was automatically recorded. At midnight, the unit downloaded the data which was available for retrieval. During this preliminary trial, only grain consumption, and not body weight was recorded.

Daily grain consumption was defined as follows:

  1. Daily Grain Consumed: summation of grain dispensed to a given bull throughout the 24 hour period between midnight and midnight. RationMaster software automatically records and stores for retrieval.
  2. Total Daily Grain Consumed: the summation of Daily Grain Consumed for all bulls in the pen on a given day.
  3. Average Daily Grain Consumed: the average of Daily Grain Consumed for all bulls in the pen on a given day.

Statistical Analyses:

All graphs with standard errors for the dependent variable Average Daily Grain Consumed were for the animals already in the pen preceding and following the day an animal movement occurred. Data for animals that were moved were edited out. Data was calculated and plotted using SuperANOVA (Abacus concepts, Inc., Berkely, CA, 1989).

All other graphs were produced with Excel version 5.0 (Microsoft Corporation). In all cases, we had more repeated measures on each experimental unit (individual grain consumption per day) than there were observations in the data set; therefore, the multivariate approach to repeated measures was not appropriate since the correlations among the observations can not be reliably estimated using that method. In order to analyze the grain consumption per day on the animals in the pen preceding and following the day a movement occurred as a repeated measure, the univariate repeated measures option of SuperANOVA (Abacus concepts, Inc., Berkely, CA, 1989) was used.

Results and Discussion:

The total daily grain consumed for the 20 animals that entered and exited the FWS pen at the Bison Evaluation Unit at different dates between February 12, 1993 and May 28, 1993 is shown in figure 1. Total daily grain consumption appears to parallel negatively with animal movement both in and out of the pen, as sharp changes occur in total daily grain consumed in response to a corresponding change in animal number. Two separate factors may be causing this response

  1. The reduction in total daily grain consumed might be caused by a slow "start-up" by the new animals entering the pen. Potential contributing factors that may serve to reduce grain intake in new animals include: the stress of being recently handled, habituating to new surroundings, the stress of establishing a new social hierarchy, and not knowing where the feed is located (learning); or
  2. The reduction in total daily grain consumed might be caused by a change in consumption by animals that were in the pen immediately prior to and after the animal movement occurred. If new animals enter the pen, it may serve to increase the number of agonistic interactions between animals as bulls establish a new social hierarchy. If animals are removed, the social hierarchy has to be reestablished, and the animals incur the additional stress of repeated handling.

When the average daily grain consumed per animal is charted against the corresponding change in animal number in the pen (figure 2) we find that the average daily grain consumed does not appear to be responding to animal movements as much as the total daily grain consumption does. By charting average daily grain consumed as opposed to the total grain consumed, we are minimizing the effects of outliers or extremes of consumption on the grain consumed, and reducing the size of the variation in grain consumption within and between days.

By editing out animals that were moved from the data set, and restricting analysis to the animals that were not moved, the effects of animal movement on animals in the pen both before and after the day of animal movement can be better described.

Removing one animal on February 16th and adding 7 animals on February 17th significantly (p<.05) impacted on the average daily grain consumption of 7 resident animals (animals within the pen both before and after the day of movement), but only for the days that the animals were moved (figure 3).

Removing one animal on March 17th did not significantly impact consumption of resident animals on the day the animal was removed (figure 4)

Adding four animals to the pen on April 8th significantly (p<0.05) reduced consumption for resident animals for the day of movement (figure 5). Although consumption on April 9th and l0th is reduced, it was not significant (p<0.05) from the consumption on the days prior to the movement.

Removal of 4 bulls on May 3rd had a significant (p<0.05) negative impact on grain consumption (figure 6) on resident animals. Movement of 4 additional bulls on May 4th provided a further insult by negatively impacting grain production a second day. The impact of this double movement was extended as consumption was significantly lower on May 6th and May 7th than May 1st and May 2nd. The removal of one animal on May 17th (figure 7) significantly (p<.05) impacted consumption of resident animals on the day of movement. This finding contradicts what happened on March 17th when one animal was also removed (figure 4).

Together, these results suggest that the removal of one animal may or may not significantly affect grain consumption for resident animals; but if consumption is reduced, it tends to be restricted to the actual day of movement. However, the movement of animals on back to back days has been shown to be very detrimental to the grain consumption of resident animals (figure 6

Rejection of Objective 1b:

From these results, the objective to compare the FWS method to the SF method for meeting a target weight was rejected. The impact of animal movement on consumption was judged by the PCBA Research Committee to be significant enough to negatively impact animal gain. Therefore, the idea of removing 1-3 animals from a group because they had reached target weight was rejected as a potential management practice.

However, it was decided that the feed-weigh station had significant benefits as a research tool and that the main trial would continue.

Section Two: Circadian grain consumption of feedlot finished bison.

Methods:

Fifteen bison bulls between 26 and 30 months of age and over 350 kg entered the Bison Evaluation Unit at the Center for Agricultural Diversification on October 28, 1994 in order to investigate circadian grain consumption over a thirteen week period. Bulls were weighed at entry and then held in the bison squeeze to accommodate placement of the collar carrying the transponder prior to entering the feed-weigh station pen (FWS).

Handling facilities consisted of a half-circle tub complete with three boxes, palpation cage and bison squeeze (Hi-Hog Farm and Ranch Equipment Ltd.). Body weight was collected from a Senstek D-2000 electronic scale placed in the half circle tub. Neither feed nor water was withheld prior to weighing.

Bison were allowed free choice access to a standard ration of rolled and blended oats and barley (1:1) via the feed-weigh station, grass hay was available from a tombstone style round bale feeder, mineral was available from a standard wooden cattle mineral feeder, and city water available from waterers (hog style).

Bulls were housed in a pen with packed sandstone shale for footing. Dividers between the pens were wire fence with plywood hung as a visual barrier. No additional shelter was provided. The pen was located adjacent to the Canadian National spur line into Dawson Creek.

Upon entry, bulls were placed on a fixed 90 day feeding period that commenced on October 28, 1994. Bulls were supplied by members of the PCBA who retained ownership of the animals throughout the trial. At the end of the 90 day feeding period, the owners were free to market their bulls as their markets demanded.

Data Storage and Handling:

Upon entry into the feed station, bulls were required to step onto the scales. As they approached within 16 inches of the feed bin, a sensor read the signal from the transponder attached to the collar around the bull's neck. A signal was then sent via cable to the RationMaster© Computer Control Unit. The bull identification number, the amount of grain dispensed ( set at 0.5 kg per minute ), and the time of entry were automatically recorded. At midnight, the unit downloaded the daily total which was available for retrieval.

In order to record the animal weight during feeding a computer program was written to: 1) constantly query each scale on a rotational basis and once a threshold , weight was achieved to; 2) contact RationMaster for animal identification; 3) match animal id with feed intake, time of day, and body weight; 4) hold all information in buffer;and 5) upon closing of the program write all information as a string of data into a text file for storage and retrieval. Each day at 8:30 hr the program was closed manually to complete that day's data and so a hard copy of the data could be printed. The text file was transferred into Microsoft Excel for editing. (Ver. 5.0 Microsoft Corporation, 1994)

Calculations:

A. Visit Weight: weight (kg) associated with visit to feed-weigh station.

B. Daily Weight: average of all valid Visit Weight collected for a 24hr period between 0:00:00 and 24:00:00 hrs. Recorded as the daily weight associated with the day's date. Weight values considered as outliers were manually removed before calculation.

C. Average Daily Gain: calculated as the difference between current weight and previous weight divided by the number of days in the interval.

D. Daily Grain Intake:

  1. Daily Grain Intake: summation of grain dispensed to a given bull throughout the 24 hour period between midnight and midnight. RationMaster software automatically records and stores for retrieval.
  2. AM: amount grain dispensed per individual (kg) between midnight and 8:30 am. Displayed by the RationMaster as the current daily total.
  3. MID: difference between the amount of grain dispensed per individual (kg) as displayed by the RationMaster at 16:30 (current daily total) and AM grain consumption.
  4. PM: difference between Daily Grain Intake and MID total.

E. Count: number of visits to the feed-weigh station

  1. AM Count: number of visits to the feed-weigh station between midnight and 8:30 am.
  2. MID Count: number of visits to the feed-weigh station between 8:30 and 16: 30
  3. PM Count: number of visits to the feed-weigh station between 16:30 and midnight.

F. Grain Feed Conversion: calculated as the average daily grain consumed divided by total average daily gain.

Statistical Analyses: 

Statistical analyses were conducted using the repeated measures analysis of covariance option of Abacus Concepts, SuperANOVA (Abacus concepts, Inc., Berkley, CA, 1989). Initial body weight was entered as a covariate with week and animal ID entered as independent variables.

Results and Discussion:

The average weekly body weight of 14 bison bulls in the circadian grain consumption trial is shown in figure 8. The removal of one bull (animal ID 9002) due to injury during week 4 had a significant effect on body weight as there was no statistical difference (p<.05) between the average weekly body weight in week 4 and the average weekly body weight in week 5. During week 9 and week 12 the bulls were handled to facilitate the recollaring of bulls that lost their transponder collars. One bull lost his collar during week 9 while two bulls lost their collar during week 12 There was no significant (p<.05) gain in body weight between weeks 9 and 10 and 12 and 13 respectively.

Rate of average daily gain averaged over the week was significantly impacted ,by the removal of the bull during week 4 and with re-collaring of bulls in week 9 and week 12 (figure 9). There were dramatic declines in average weekly gain in the weeks associated with the animal handling.

Average weekly total grain consumed declined significantly (p<.05) at week 4 and at week 9 and week 12 (figure 10). This decline occurs correspondent to the decline in both average weekly body weight and average weekly daily gain.

Bison consumed more of their daily grain intake during the evening period than in the morning or mid-day (figure 11a). When the percentage of daily grain consumed during the morning, mid-day and evening period (figure 11b) are compared with the percentage of daily grain consumed during the morning, mid-day and evening period in the previous study (figure 11c), we find that the graphs correspond to each other. However, animals in the animal movement trial consumed a smaller percentage of grain in the midday than animals in this trial. Two possible explanations for this finding include: 1) the effect of animal movement, since most of the animal handling occurred during the mid-day period; or 2) the effect of season may have affected grain intake during the summer months.

Bison consistently consumed more grain in the evening period throughout the 13 week feeding trial (figure 12). With one minor exception (animal ID 9005), all bison followed the same pattern of consuming more grain in the evening than in the morning or midday (figure 13) which suggests that bison feeding behaviour might be highly coordinated or affected by social facilitation. Bison are known as a species to be very gregarious.

The graph of the average of daily visits to the FWS per week (figure 14) is comparable to the graph of the average weekly total grain consumed (figure 10), suggesting that there is a positive relationship between the number of visits to the FWS and grain consumption. Bison visited the FWS more in the evening and visited the FWS the least in the morning (figure 15) over the 13 week period, which is consistent, with the average daily grain consumption over the 13 week period (figure 12)

When the average daily visits during the morning, mid-day and evening to the FWS per individual animal (figure 16) are compared to the total average daily grain consumed per individual animal (figure 13) the graphs approximate each other. However, bison appear to be making more visits in the morning and less visits in the evening relative to the amount of grain consumed. These results suggest that when individual bison visit the FWS in the morning they consume less grain during that visit than when they visit the FWS in the evening.

Overall, the data collected during this study imply that animal handling to remove an injured animal from the pen and later subsequent handling to replace lost transponder collars had a significant (p<.05) negative impact on average weekly body weight, average weekly gain, and average weekly total grain consumed. Based on these results, it is recommended that bison be handled as infrequently as possible as handling appears to be detrimental to animal production measures.

The feed-weigh station should not be used as a method of grain finishing bison bulls if there is no assurance that the transponder collars will stay on the bulls. During the winter 1994-95 feeding period frequency of loss of the transponder collars was greater (3) than the previous winter (0) and is believed to be directly related to the length of the horn on the bulls. Winter 1994-95 bulls had been tipped (only the outermost 1-3 inches removed) previous to entry while in the previous year dehorning was to within 2 inches of the head.

This research supports the PCBA speculation that the FWS should not be used as a method of meeting a target weight because of the loss productivity associated with handling to remove animals once finished.

Section Three: Comparison of a computerized feed-weigh station vs. self-feeder as a method of grain finishing bison.

Methods:
Bison bulls between 26 and 30 months of age and over 350 kg entered the Bison Evaluation Unit at the Center for Agricultural Diversification in late October of 1993 and 1994 for the purpose of comparing the computerized feed-weigh station (FWS) as a method of grain finishing bison to the self-feeder (SF) method. Bulls were weighed at entry and randomly assigned into one of two groups: BF4 (FWS) or BF3 (SF) (table 3).

Table 3: Number of bison in feed-weight station and self-feeder groups in 1993 and 1994.

Year Pen Days between weighing # of Bulls
1993 BF4 (Feed-Weigh Station FWS) 35, 90 15
1993 BF3 (Self-Feeder SF) 35, 90 14
1994 BF4 (Feed-Weigh Station FWS) 45, 90 14
1994 BF3 (Self-Feed SF) 45, 90 15


Bulls entering the feed-weigh station group (FWS) were held in the bison squeeze to accommodate placement of the collar carrying the transponder. In Year 2, tagging, dehorning and ivermectin injections occurred previous to entry.

Handling facilities consisted of a half-circle tub complete with three boxes, palpation cage and bison squeeze (Hi-Hog Farm and Ranch Equipment Ltd.). Body weight was collected from a Senstek D-2000 electronic scale placed under the first box (Year 1) or in the half-circle tub (Year 2). Neither feed or water was withheld prior to weighing.

Bison that were placed in the self-feeder group (SF) had free choice access to a standard ration of rolled and blended oats and barley (1:1), good quality forage (barley straw in Year 1 and grass hay in Year 2), cattle mineral and water. Grain was fed in a portable bison grain self-feeder, hay available from a tombstone style round bale feeder, mineral available in tubs mounted on the end of the grain feeder and city water available from waterers (hog style). The feed-weigh station group were fed in an equivalent manner except free choice access to grain was via the feed-weigh station and mineral was available from a standard wooden cattle mineral feeder. Bulls were housed in large pens that were previously described in Section Two.

Upon entry, bulls were placed on a fixed 90 day feeding period that commenced on October 26, 1993 (Year 1) and October 28, 1994 (Year 2). Bulls were supplied by, members of the PCBA who retained ownership of the animals throughout the trial. At the end of the 90 day feeding period, the owners were free to market their bulls as their markets demanded.

Data Storage and Handling:
Body weight collected from weighing within the handling facilities and feed intake data (except grain from feed-weigh stations) were recorded manually, compiled and entered into a computer based record system (MS Works ), edited for completeness and verified for accuracy (MS Excel) by reconciling raw and entered data. Storage and handling associated with the FWS grain and weight data has been described in Section Two.

Calculations:
All data and calculations for ADG, grain, and forage consumed are based on the 90 day feeding period, unless otherwise stated. No attempt was made to quantify water intake.

A. SF Group:

1. Average Daily Gain: bulls were weighed in the handling facilities on entry (DAY0), at DAY35 in year 1993 and DAY45 in year 1994, and DAY90. Average Daily Gain is determined by the difference between current weight and previous weight divided by the number of days in that interval. This results in an individual average daily gain for DAY0 to DAY35/45, DAY35/45 to DAY90, and DAY0 to DAY90 (Total).

2. Average Daily Grain Intake: grain self-feeder was weighed before entry and on exit from feedlot pens. Commercial scales available at the adjacent South Peace Seed Cleaning Plant (SPSCP) were used and grain consumption was determined by difference. Average daily grain consumption was determined as the total grain consumed divided by number of days between weighing for DAY0 to DAY35/45 (Average Daily Gain-Start to Middle, ADG-SM), DAY35/45 to DAY90 (Average Daily Gain-Middle to End, ADG-ME), and DAY0 to DAY90 (Average Daily Gain-Start to End, Total ADG-SE).

Average daily grain consumed on an individual basis was determined by dividing the average daily grain consumed (by the group) by the number of head within the group. If bulls were removed from the group between weighing, average daily grain consumed per day was calculated by using the number of "bull days". This results in an average per head consumption and assumes equal intake for each bull.

3. Average Daily Forage Intake: since forage was available for consumption from round bale feeders and there was no accounting of daily waste, ADFI may be more adequately described as Average Daily Forage Used. Sample bales from each lot were weighed at the SPSCP commercial scale to provide an average weight. ADFI was calculated as the total kg forage fed between two given dates, divided by the number of bull days. This results in an average per head consumption assuming equal intake.

4. Total Feed Conversion: calculated as the total daily grain intake and the total daily forage divided by the total average daily gain.

B. FWS Group:

1. Visit Weight: weight (kg) associated with visit to feed station.

2. Daily Weight: average of all valid Visit Weight collected for the 24hr period between 8:30 am and 8:30 am the following day, and later adjusted to midnight to midnight. Recorded as the daily weight associated with the date at the beginning of the interval. Weight values considered as outliers were removed from the calculation. These values were instances when bison tripped the feed-weigh station scale but did not stand on the scale for a sufficient length of time in order to get a valid reading, and no grain was actually dispensed.

3. Average Daily Gain: calculated as above (SF Group) except for DAY45 and DAY90 the weight was taken from the feed station scale readout.

4. Daily Grain Intake:

a) Daily Grain Intake: summation of grain dispensed to a given bull throughout the 24 hour period between midnight and midnight. RationMaster software automatically records and stores for retrieval.

b) Day35/45 Grain Intake: amount grain dispensed per individual (kg) displayed by the RationMaster as the current daily total and then summed over the 0 to 35/45 day period.

c) Day45/90 Grain Intake: amount grain dispensed per individual (kg) displayed by the RationMaster as the current daily total and then summed over the 55/45 day to 90 day period.

d) Total Grain Intake: amount grain dispensed per individual (kg) displayed by the RationMaster as the current daily total and then summed over the 0 to 90 day period.

5. Average Daily Grain Intake: calculated as the summation actual daily grain dispensed divided by the number of days between intervals weighing for DAY0 to DAY35/45, DAY35/45 to DAY90, and DAY0 to DAY90 (total). Assumes grain dispensed equals grain consumed.

6. Average Daily Forage Intake and Total Average Daily Forage Intake: as above.

7. Total Feed Conversion: calculated as the total daily grain intake and the total daily forage divided by the total average daily gain.

Results and Discussion

The average daily gain by pen was comparable between pens (table 4), with one noticeable exception. The average daily gain for pen BF3 (SF) in 1993 was extremely low (0.18 kgd-1 ) but it is not unusual based on past performance records at the Bison Evaluation Unit. The total average daily gain observed (ADG-SE) in this study are similar to the total average daily gain of bulls that were placed on fixed 90 day fall feeding periods in other trials conducted at the BEU (Rutley 1992a, Rutley and Church 1995). There appears to be little difference between the feed-weigh station and the self-feeder in terms of average daily gain (see Hussey 1995 for a summary of economic implications).

The total grain consumption between pens in 1993 was just about identical (table 5), which is surprising given the extremely low rate of average daily gain observed in pen BF3(SF) in 1993 (table 4). While bulls consumed very similar amounts of grain in 1993, alike grain consumption did not result in comparable average daily gain. This parallels the observation made by Rutley (1992a) where consumption and gain did not appear to be directly related. In 1994 the grain consumption was almost double in the self-feeder pen BF3(SF) than in the feed-weigh station pen BF4(FWS) (table 5).

While grain intake was very different in 1994 between pen BF4(FWS) and BF3(SF) the forage intake were alike (table 6). And while the grain intake between pen BF4(FWS) and BF3(SF) was very similar to 1993, the forage intake between the two pens was not. In 1993 forage intake was higher in the BF4(FWS) pen than BF3(SF). These results suggest that forage and grain consumption are somewhat mutually exclusive. When an animal consumes one feed source, it reduces its ability to consume another feed source.

While grain intake and forage intake tended to vary, feed conversion was very comparable, especially in 1994 (table 7). Feed conversion was alike between 1993 and 1994 with the exception of pen BF3(SF).

Equivalent feed conversion ratios between pens suggest that the utilization of the feed-weigh station as a method of grain finishing bison bulls is an acceptable alternative to the self-feeder method. More importantly, research data obtained from animals using the FWS can be directly applied and compared to data obtained from the SF method under conditions equivalent to the BEU.

Table 4: Average daily gain (KG) by pen.

Year

Pen

# of
Bulls

Days in
interval

ADG-SM

ADG-ME

ADG-SE

1993

BF4 (FWS)

15

35, 90

1.48

0.62

0.96

1993

BF3 (SF)

14

35, 90

0.18

0.72

0.51

1994

BF4 (FWS)

14

45, 90

1.10

0.55

0.83

1994

BF3 (SF)

15

45, 90

1.25

0.82

1.03

Table 5: Total grain consumption (kg) by pen.

Year

Pen

# of
Bulls

Days in
interval

SM Total
Grain Intake

ME Total
Grain Intake

SE Total
Grain Intake

1993

BF4 (FWS)

15

35, 90

2348

6027

8375

1993

BF3 (SF)

14

35, 90

2940

5434

8374

1994

BF4 (FWS)

14

45, 90

2935

2679

5614

1994

BF3 (SF)

15

45, 90

4041

5838

9879

Table 6: Total forage consumption (kg) by pen.

Year

Pen

# of
Bulls

Days in
interval

SM Total
Forage Intake

ME Total
Forage Intake

SE Total
Forage Intake

1993

BF4 (FWS)

15

35, 90

3324

3988

7313

1993

BF3 (SF)

14

35, 90

2576

2171

4747

1994

BF4 (FWS)

14

45, 90

1435

3012

4447

1994

BF3 (SF)

15

45, 90

1518

3207

4725

Table 7: Total feed conversion by pen.

Year

Pen

# of
Bulls

Days in
interval

SM Total
Feed Conv.

ME Total
Feed Conv.

SE Total
Feed Conv.

1993

BF4 (FWS)

15

35, 90

7.3

19.6

12.2

1993

BF3 (SF)

14

35, 90

62.0

13.8

20.5

1994

BF4 (FWS)

14

45, 90

6.3

16.3

9.6

1994

BF3 (SF)

15

45, 90

6.6

16.3

10.5

Implications:

There is clear evidence that handling bison and moving animals in or out of the finishing group negatively impacts grain consumption and average daily gain.

Management practices recommending minimal movement of finishing animal are sound from a production maximization position.

The feed-weigh station was rejected as a method of finishing bison to a target weight because of the negative impact on the remaining bulls within the pen. No alternative solutions have been identified.

The feed-weigh station is not a recommended method for finishing bison because:

1) it is only equally efficient to the self-feeder method at best and much more expensive;

and 2) the loss of productivity (average daily gain) associated with replacing transponder collars is significant, since there was no collar loss with completely dehorned bulls, and new technology such as placement of the transponder chip in an ear tag exist, elimination of this second problem appears plausible.

Because the feed-weigh station is equivalent to the self-feeder method for grain consumption, average daily gain and feed conversion it can be used successfully as a research tool with the results having direct application to the self-feeder finishing industry. The feed-weigh station could also be used in a "test station" situation to determine individual animal efficiency when modified so that a complete pelleted grain and forage ration could be fed or bulls have individual access to pelleted grain and forage separately.

The problem of obtaining body weight of finishing bulls without disturbing productivity remains elusive, alternative ideas will need to be developed.

References

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