Wintering mature beef cows on straw or stover

Dale Burr and V.L. Anderson
Carrington Research Extension Center
North Dakota State University

Introduction
Beef cows in the Northern Plains are wintered on a wide variety of feeds. The economically astute and nutritionally aware cattleman will combine the most cost effective feeds that meet the cows requirements. Obviously, those requirements change with advancing gestation and the stress of winter weather.

In regions where small grains are grown, the feed supply often includes large amounts of straw. The acres planted to corn is increasing in the region due to the development of hardier, shorter season varieties. The corn residue referred to as stover provides another feedstuff for consideration.

Biomass from both crops provides less than the required nutrient concentration, thereby requiring supplementation for wintering cows, especially during late gestation. However, home grown feeds or low cost processing co-products can be mixed with these residues to make a balanced diet. This study was conducted to compare the two residues in diets for wintering beef cows.

Materials and Methods
Mature British cross-bred beef cows (n=66) were randomly allotted to one of four pens with two pens assigned per treatment. Treatments were wheat straw or corn stover offered free choice in big round bale feeders. Straw and stover had been harvested with a stack wagon and fed with a grapple fork. Residue feeders were refilled when less than a one day supply of straw or stover remained. Residues were sampled as fed and as the refused portion.

All cows were fed the same totally mixed base ration consisting of (as fed) 20.93 lb corn silage, 5.19 lb oat hay, and 5.19 lb ground screenings with .15 lb trace mineral package on a per head per day basis. Cows were weighed and condition scored (9 point system) at the start of the trial (December 24) and just prior to calving (March 13). Calf birth weights were taken within 12 hours of birth after calves nursed.

Results and Discussion
Dry matter intake from the base ration was 15.81 pounds or approximately 67% of dry matter requirements for a 1300 pound cow during the last trimester of gestation. Residue intake was not quantified in this study. Another study to measure intake for a number of individually fed cows will be conducted later.

Straw and stover were not completely consumed as both were offered as large round bales and some coarse material remained. The bulky, heavy stalk material from stover was not consumed and accumulated in the feeders. This highly lignified material accounted for approximately 1/3 of the original volume of stover. The nutritional value of stover varies greatly with the location of the biomass on the plant. Material from leaves, cobs, and stalk above the ear is more nutritious than brom below the ear. There is no method of separating these components in harvesting stover so a free choice system allows voluntary consumption. Feeders that fill with the larger stalk material must be emptied or moved on a regular basis.

From the chemical analysis conducted on samples of the two residues at the time of feeding and again when the feeders were nearly empty (Table 1), it is apparent that dry matter decreased as moisture collected on the refused residue, primarily from falling and blowing snow. Other nutrients were similar with ADF increasing as the more palatable portions of the residue were selected and consumed by cows.

Cow weights and condition scores were not affected by type of residue offered (Table 2). Stover cows gained 153 pounds vs 143 for straw fed cows. Condition scored increased by .23 for stover compared to .14 for straw cows. This demonstration trial indicates cows will perform similarly on a base ration with either straw or stover offered to appetite.

Table 1. Chemical analysis of straw and stover sampled as fed and as the refused portion.

  Straw Stover
Dry matter
When fed 80.37 75.41
Refused 53.13 52.13
Ash
When fed 10.17 6.01
Refused 9.55 5.37
Crude protein
When fed 7.88 3.77
Refused 7.05 3.90
ADF
When fed 51.45 51.92
Refused 55.90 55.90
NDF
When fed 77.41 84.79
Refuses 79.09 84.59
Calcium
When fed .38 .30
Refused .33 .27
Phosphorous
When fed .20 .08
Refused .18 .08

  
Table 2. Performance of beef cows wintered on a base ration with free choice straw or stover.

Item

Treatment

Straw Stover Std Err
Number 33 33  
Initial cow wt, lb (Dec 23) 1327 1329 21.8
Final cow wt, lb (Mar 13) 1470

1482

21.8
Cow weight gain, lb 143

153

4.65
 
Initial Condition Score (Dec 23) 5.76 5.64 .10
Final condition Score (Mar 13) 5.89 5.86 .10
Condition Score change .14 .23 .09
 
Calf birth weight, lb 92.9 95.0 2.04
Calf sex (1=F, 2=M) 1.39 1.58 .09

     
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