Effects of Bedding During the Winter on Performance of Growing Heifers
and Finishing Steers
and Impact of Straw on Nutrients in Manure

Vern Anderson, Dale Burr, Tim Schroeder, Larry Swenson* and Ezra Aberle

Carrington Research Extension Center and *Soil Science Department

North Dakota State University

Progress Report

ntroduction

Livestock perform better when not subjected to environmental stress.  Feeding cattle in the winter, with snow, cold winds, and subsequent spring mud creates a challenge for feedlot managers.  Some feedyards use bedding for cattle comfort, with straw, the predominant bedding material.  In Alberta, it is considered to be a critical management tool for making feedlot cattle comfortable in commercial yards.  Many North Dakota farmer-feeders use straw liberally for their calves and haul the raw manure back to cropland as part of their fertility program.  Bedding is not used in some commercial feedlots in North Dakota.

Composting manure will stabilize nutrient release for crops and decrease the volume of product to haul. Nitrogen volatilization from manure is considered to be a major environmental problem.   Some estimates credit livestock for up to 70 percent of atmospheric ammonia produced by animal manure.  Limiting nitrogen losses should increase fertility value of manure as nitrogen is retained in composted manure.   The use of bedding for feedlot cattle may mitigate environmental effects on cattle performance and potentially reduce ammonia emissions. 

The impact of bedding on animal performance and economics has not been determined in North Dakota.  Further, the inclusion of straw in the manure may improve the composting characteristics and mitigate nitrogen loss by reducing volatilization of ammonia.  This trial was initiated as a multi-year study to evaluate bedding for finishing steers and growing heifers in North Dakota feedyards.

Procedures

Calves born and raised at the Carrington Research Extension Center were allotted to three bedding treatments after weaning and preconditioning in November of 2001.  The bedding treatments were: no bedding, modest or normal bedding, and generous or extrabedding.  Calves were blocked by sex with three pens of steers (n=55) in one block and three pens of heifers (n=53) in another.  All pens were identical in size, orientation to wind, trees, and fencing, and waterers, and bunkline feeeders.  Steers were fed the same finishing diet (84% concentrate) to appetite with a growing diet (50% concentrate) offered to all heifers.  Feed bunks were read daily at 8 AM and the ration adjusted according to intake with feed delivered between 8:30 and 10:00 AM.  Treatment groups of 17 to 18 head were penned together allowing approximately 250 square feet per animal.  All calves were weighed every 28 days to compare performance during segments of the winter and spring.  Steer calves were fed to finish weight and marketed at area meat markets and at a major meat processor.  Carcass data were collected and economic returns calculated based on feed intake, gain, feed efficiency, and carcass value.   Heifer calves were grown for replacements.  

In describing treatments, the modest bedding was a minimalist approach to keeping some bedding under the calves during inclement winter weather.  Generous bedding is quantified as double the amount provided in the modest bedding treatment.  Straw was added approximately weekly with longer periods between new straw additions when weather allowed.  Big round bales were deposited in the pens and spread throughout the bedding area with a wheel loader and grapple fork.  Calves had access from the bedded area to feedbunks and water fountains on concrete aprons.

During the trial, calves appeared to have substantial variation in the amount of tag or manure attached to their hide associated with bedding treatment.  A five point scoring system was developed to quantify the amount of tag on the hide and steers were scored prior to going to market.  Three people independently scored each steer.  The scoring system was 1=no tag, clean hide; 2=small lumps attached to the hide in limited areas; 3=small and large lumps attached to the hide in larger areas; 4=small and large lumps of manure attached to the hide in even larger areas along the hind quarter, stomach, and front shoulder; and 5=lumps of manure attached to the hide continuously from brisket to rear quarter, and under the belly.   

To evaluate the effects of bedding in lowering nitrogen losses, manure from each pen was weighed as it was removed, and sampled for dry matter, organic matter, nitrogen (Kjeldahl N and ammonium-nitrogen) , phosphorous (%P₂0₅), and potassium (K₂0).  Manure from each pen will be thoroughly mixed and composted for 1 to 2 months until stable and mixed again prior to a second sampling.  Comparison of analysis of raw and composted manure will yield data from which to estimate the amount of nitrogen volatilized as ammonia for each treatment.  Only manure analysis from pens sampled prior to composting are reported in this paper.

Results

Animal performance

Data reported in this paper are observations from one year with one set of steers and heifers.  Years will be used as replicates to sample variation in weather over multiple winters.  Weather during the 2001-2002 winter was very mild with little snow and only a few days of sub-zero temperatures. 

Feed intake appears to be similar between treatments for the finishing steers overall but shows some variation by monthly periods (Table 1).  Intake for growing heifers appears to be more consistent with a numerically greater feed consumption for heifers with no bedding (Table 2).  It is possible that animals consumed small amounts of straw in the trial. 

Clean steers in bedded pen gained faster.                                                          No bedding steers carry significant manure tag.

Table 1.  Effect of bedding on performance of finishing steers

*Actual weight gains may be lower than reported for the no bedding treatment as animal weights included manure tag 

Clean, comfortable heifers in a bedded pen.
 

Table 2.  Effect of bedding on performance of growing heifers

*Actual weight gains may be lower than reported for no bedding treatment as animal weights included manure tag. 

Daily gains appear to highly favor bedding for finishing steers, without regard for amount of bedding.  Steers with no bedding gained 3.16 lbs./day vs. 3.63 and 3.60 for normal and extra bedding, respectively.  Gains during the spring weigh period were dramatically lower for non-bedded steers at 1.50 lbs./day, contributing to the lowered gains. Heifers showed much less improvement in gain due to bedding.  No bedding resulted in 1.94 lbs./day vs. 2.02 and 2.04 for normal and extra bedding, respectively, with some monthly variation observed.

Feed efficiency is calculated on a pen basis by dividing pounds of dry matter consumed by pounds gained and reported as pounds of gain per unit feed.  For steers, normal bedding (.184) appears to provide similar feed efficiency as no bedding (.179) with lower values for extra bedding (.161).  Some month to month variation is evident. Feed efficiency for heifers appears to improve with increasing bedding, however.

Animal Tag

Weights of animals reported above includes manure tags attached to the hair of steers and heifers.  The visual scoring system described previously reveals minimal tags attached to the extra bedding animals, more tag on the normally bedded animals , and much more associated with no bedding for both steers and heifers (Table 3).  There was no weight estimate made for tag on the different treatments.

Table 3.  Effect of bedding on amount of manure (tag)* on hides of steers and heifers

* Scored on a 1-5 scale; 1=clean hides, 5= tag covering all of lower animals hide

Carcass Quality 

Carcass traits appear to be significantly improved with bedding (Table 4) starting with increased hot carcass weight which is a reflection of improved gains in the bedded treatments.  Dressing percent also appears to improve with bedding, partially due to amount of manure tag on the non-bedded cattle.  Quality grade evidence by marbling scores and percent of carcasses grading choice or better shows increases with bedding.  Yield grade, fat thickness and rib eye area are all variables affected by level of condition.  Steers with no bedding may have improved in carcass quality with another 70 pounds of gain which would have taken another 20 days on feed.

Table 4.  Effect of bedding on carcass quality

* Yield grade is a measure of fat to lean ratio, 1=lean, 5=fat.

Economics of Bedding

Normal bedding required just over 200 pounds per head with extra bedding over 400 lbs. for nearly weekly application (Table 5).  With straw valued at $30.00 per ton, cost of bedding amounted to an average of $3.11 per head for normal bedding and $6.22 for extra bedding for both groups of animals.  Cost per pound of gain (Table 6) including bedding and feed is calculated at $.284 for no bedding, $.255 for normal bedding, and $.268 for extra bedding. Returns above feed and bedding costs when cattle are sold on a flat bid of $1.12/lb. carcass produced a return of $48.15 for no bedding, $91.05 for normal bedding, and $84.79 for extra bedding.  If carcasses were sold on a grade and yield basis at $1.15 for Choice or better and $1.10 for Select, returns are calculated at $43.42 for no bedding, $92.97 for normal bedding and $95.69 for extra bedding.  Carcass price breaks from Choice to Select vary depending on the time of year and demandm but in this example, there appears to be little difference except for a modest increase in returns to extra bedding. 

Table 5.  Amount of bedding used and cost per head for finishing steers and growing heifers
during the 141-day winter feeding period.