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USING STRAW IN COW WINTERING RATIONS

Past research at this station has indicated that small grain straw and adequate supplemental protein can replace up to two-thirds of the hay fed in wintering rations to pregnant beef cows.

In this trial a 100 percent mixed brome and crested wheatgrass hay ration is compared with a 50 percent hay - 50 percent oat straw ration for wintering pregnant beef cows. Both rations were fed in the long form. There was no supplemental protein fed to either of the ration groups.

The trial has been run for three winter feeding periods with the station's commercial Hereford cow herd.

In 1972-73 the calves were weaned about November 1, and the cow herd was grazed on good to excellent native grass range until the end of the month. During this one month period, despite supplemental feeding of protein blocks, the cows lost an average of 47 pounds of weight, with a corresponding loss of body condition. In 1973-74 the calves were weaned on November 1, and the cow herd was grazed on grain stubble aftermath until the end of the month. Cow weight loss in 1973-74 pre-trial grazing averaged 45 pounds per head. The 1974-75 pre-trial grazing was on good native grass pasture on the station's Pyramid Park summer grazing range in the Badlands. The cow weight loss in 1974-75 was 23 pounds per head.

On November 26, 1974 the cows were randomly allotted by age into two feeding groups. Group A was fed the mixed hay ration and group B was fed the 50 percent mixed hay - 50 percent oat straw ration. Both groups of cows had a salt-mineral mixture and water available free choice. As in past years, both groups were held in lots with a slotted board fence for protection from wind and weather.

On January 31, 1975, thirty days before the cows were scheduled to start calving the straw feeding was discontinued and replaced with the mixed hay ration fed to appetite. As each cow calved, she was moved into a post calving lot and given two pounds of rolled oats in addition to the hay until the cows were turned on grass in early May.

Three years data on changes in cow liveweight, feed consumption, wintering costs, calf birth weight and calf mortality are summarized in tables 1, 2 and 3.

This information shows a ration of 50 percent mixed hay - 50 percent oat straw can be fed for a period of 60 days without adversely affecting calf birth weight and livability.

Young cows that were wintered on the 50 percent mixed hay - 50 percent oat straw ration lost the most body weight, which was expected. Cows that are carrying average to moderate condition can afford this weight loss without serious effect. Unless young cows, under 4 years old, have good body condition in the fall they should not be expected to compete and exist on the 50 percent straw - 50 percent hay ration.

Table 1 - Three year summary of cow weight change-wintering trial, 1973-75
  Avg. wt on hay Avg. wt. on hay & straw
3 yr. old 4-5-6 yr. old 7 yr. & older 3 yr. old 4-5-6 yr. old 7 yr. & older
Pre-trial
Nov. 1, 1972-73 952 1085 1171 971 1107 1179
Nov. 1, 1973-74 913 1135 1166 914 1098 1192
Oct. 16, 1974-75 926 1028 1148 898 1036 1142
3-Year Average 930 1082 1162 927 1080 1171
 
Dec. 1, 1972-73 917 1043 1121 924 1054 1126
Dec. 1, 1973-74 906 1092 1098 890 1044 1116
Nov. 26, 1974-75 884 1005 1129 874 1025 1123
3-Year Average 902 1046 1116 896 1041 1121
Wt. change1
1972-73 -35 -42 -50 -47 -53 -53
1973-74 -7 -43 -68 -24 -54 -76
1974-75 -42 -23 -19 -24 -11 -19
3-Year Average -28 -36 -46 -32 -39 -49
 
Feb. 1, 1973 921 1052 1118 899 1037 1118
Feb. 1, 1974 912 1120 1145 920 1074 1164
Jan. 31, 1975 953 1069 1195 869 1013 1122
3-Year Average 928 1080 1152 896 1041 1135
Wt. Change
Dec. 1 - Feb. 1, 1973 +4 +9 -3 -25 -17 -8
Dec. 1 - Feb. 7, 1974 +6 +28 +47 +30 +30 +48
Nov. 26 - Jan. 31, 1975 +69 +64 +66 -5 -12 -1
3-Year Average +26 +34 +36 0 -.3 -13
1Weight loss on native grass pasture in 1972-73, 1974-75 and on grain stubble aftermath in 1973-74.

 

Table 2 - Feed consumption and cost - cow wintering trial, 1973-75
  Hay Hay & Straw

1973 data

Mixed hay, lbs. 69,300 43,350
Oat straw, lbs. --- 27,750
Feed/hd./day, lbs. 21.4 21.4
Feed cost @ $18/ton, hay - $10/ton, straw
Per head/day 0.19 0.16
Per head, entire trial $11.71 $9.79
Savings/cow/month 0.96

1974 data

Mixed hay, lbs. 76,320 37,274
Oat straw, lbs. --- 37,274
Feed/hd./day, lbs. 21.6 21.4
Feed cost @ $30/ton, hay - $15/ton, straw
Per head/day 0.32 0.24
Per head, entire trial $19.08 $14.22
Savings/cow/month $2.35

1975 data

Mixed hay, lbs. 68,796 34,175
Oat straw, lbs. --- 34,726
Feed/hd./day, lbs. 21.6 20.0
Feed cost @ $40/ton, hay - $15/ton, straw
Per head/day 0.43 0.27
Per head, entire trial $28.08 $17.80
Savings/cow/month $4.67

 

Table 3 - Calf birth weights and mortality - cow wintering trial, 1973-75
  Hay ration Hay & straw ration
3 yr. old 4-5-6 yr. old 7 yr. & older 3 yr. old 4-5-6 yr. old 7 yr. & older
Heifer calves

No. head 1973

6

10 10 8 10 9

1974

4 7 7 5 16 4

1975

6 14 8 5 8 10
 
Birth wt., lbs. 1973 61 64 65 53 62 66
1974 61 66 73 61 68 73
1975 61 67 72 58 68 65
Steer calves
No. head 1973 2 12 8 5 13 6
1974 7 17 14 7 14 13
1975 3 8 8 3 15 7
 
Birth wt., lbs. 1973 56 66 65 67 68 69
1974 67 72 71 72 73 63
1975 71 71 74 66 72 71
 

Combined avg. birth weight, lbs.

Hay ration Hay & straw ration
All calves 1973 641 642
All calves 1974 703 684
All calves 1975 705 686
Three year average 68 67
1One cow died, 2 cows open, 1 cow aborted, 1 calf died.
2One calf born dead, 2 late calves - no birth weight.
3One cow open, 2 cows died, 1 calf died.
4One cow open.
5One calf died of pneumonia.
62 calves born weak, died from exposure, 1 cow aborted, 1 calf born breach - died, 1 late calf no birth weight.

Summary: Straw can be used effectively in cow rations to reduce wintering costs, to aid stockmen in building a hay reserve for future years or sale or to stretch insufficient feed supplies.

Use of straw in the ration reduced wintering costs about $1.00 per cow per month in 1973; $2.35 in 1974; and, $4.67 per cow per month in 1975.


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