Cattle producers are advised to test their forage to improve their ability to meet cow nutritional requirements.
A Kansas State University Extension publication said analytical forage testing occasionally is viewed by cattle producers as an exercise with limited practical application, generating numbers only a nutritionist can discern.
However, practical application is the fundamental reason for evaluating forages and feeds.
Almost every operation has several different types of hay available. So Justin Waggoner, extension beef specialist, analyzed a hypothetical spring-calving cow/calf operation with three.
| Item | A | B | C |
| Dry Matter, % As fed | 86.0 | 88.0 | 86.4 |
| Crude Protein, % Dry matter | 16.0 | 4.8 | 10.7 |
| Acid Detergent Fiber, % Dry matter | 37.7 | 52.0 | 37.3 |
| Net Energy Maint., Mcal/lb | 0.59 | 0.41 | 0.58 |
| Net Energy Gain, Mcal/lb | 0.33 | 0.17 | 0.32 |
All three forages had 86% to 88% dry matter but different levels of Crude Protein, Acid Detergent Fiber and the subsequent energy estimates (Net Energy Maintenance and Net Energy Gain) derived from ADF.
The ADF number represents the amount of cellulose and lignin within the forage and is inversely correlated with digestibility.
Forage B had the greatest ADF, which corresponds to a lower NEm value. The ADF and CP content of forage B also suggests it is a relatively mature, lower-quality forage.
Forages A and C have similar ADF content, but forage A has a greater CP than forage B.
APPLICATION AND USE
The application and use of the forage analyses requires an estimate of animal nutrient needs. For this example, Waggoner used the protein requirements of beef cows. The crude protein requirements of mature reproducing beef cows can be summarized by the numbers 7, 9 and 11.
The CP requirements of a pregnant, non-lactating beef cow can be met by a diet containing about 7% CP. The CP requirements of a cow during the third trimester require a diet that contains about 9% CP, and once the cow has calved, the diet should contain 10% to 11% CP.
That is a general rule, though, and there are several factors like body condition and forage availability that must be taken into account.
The CP content of the three listed forages ranges from 4.8% to 16%. Forage B has the lowest CP content and would not supply enough to meet the requirements of non-lactating pregnant cows.
However, if forage B were used in combination or supplemented with either forage A (16% CP) or C (10.7%), it could be used.
Forage C matches well with the 9% and 11% CP required by third trimester and lactating cows.
Forage A, which contains 16% CP, exceeds the dietary requirement of a lactating cow. However, forage A could be used with either forage B or C as a supplemental protein source or even energy if fed with forage B.
Producers don’t need to be a nutritionist to use a forage test, just a working knowledge of what the numbers mean and animal requirements.
CATTLE, BEEF RECAP
Cash cattle sold this week in the Plains at $126 per cwt on a live basis, steady to down $1 from the bulk of last week’s transactions. On a dressed basis, cattle sold steady at $200.
No cattle were sold Wednesday on the Livestock Exchange video auction.
The USDA’s choice cutout Thursday was down $0.46 per cwt at $209.60, while select was up $0.22 at $204.54. The choice/select spread narrowed to $5.06 from $5.74 with only 64 loads of fabricated product sold into the spot market.
The CME Feeder Cattle index for the seven days ended Wednesday, was $147.95 per cwt, up $0.44. This compares with Thursday’s Mar settlement of $149.55, up $4.50.