Forage Quality - Know what your are feeding

Sam Strahan, Manager Feed Technical Services

Forage Quality

For many years I, and other nutritionists, have recommended the need to test your forages prior to winter feeding. The abundant moisture we often get in Virginia is much appreciated, but at the same time, can often result in some poor quality hay being made. The goal with animal producers, whether cattle, sheep, goats or horses, is to feed to meet the animal's needs. In a wet year like 2013, hay quality may have been variable on any given farm, if the grass was unable to be cut on time, was more mature than normal due to rapid growth, or got rained on after being cut.

What difference does hay quality make? Since forage is typically the main component of the diet for your animals during cold weather when pasture is not available, poor quality hay often will not meet the dietary needs of the animal, and therefore leads to higher supplement costs. So how does one evaluate hay quality? The most important nutrients I consider when advising producers is the energy level (TDN, calories, Net energy), NDF (fiber) and protein. Mother Nature has designed grass to grow tall, with the expectation it will make a seed head and reproduce. As the stem grows and matures, more indigestible fiber is created, and the energy level decreases. Therefore, a shorter plant typically contains higher energy (before the seed head emerges).

In the table below are lab results of some hay and pasture sampled this fall by CFC field reps. A few noteworthy observations:

·  Fresh pasture, even in late October is much higher quality than dry hay, which relates to the comments above about plant maturity. When transitioning from pasture to hay, adjustments often need to be made to the diet.
·  Many people consider protein to be the most important indicator of forage quality. However, energy (TDN or calories) is most often the nutrient that requires supplementation. The “High TDN” hay below has a much higher Relative Feed Value, although protein is lower.

FORAGE TYPE

TDN

NDF

CRUDE PROTEIN (CP)

RELATIVE FEED VALUE (RFV)

Fescue pasture-10/23/13

70.5

48.6

16.4

130

High TDN Grass Hay

61.9

59.8

9.4

98

Low TDN Grass Hay

50.6

69.6

11.1

67


We know from research thathigh NDF limits intake, so this presents a two-fold problem of meeting energyneeds of our animals. The high fiber, low TDN hay will limit the amount a cow(sheep, goat, horse) can eat and it is already lower in energy. Let me use anexample of how the above three forages contribute toward the requirements of a1200 lb lactating beef cow (fall calving) (adapted from McCann, Virginia TechLivestock Update, Oct. 2013):

Estimated
Daily Forage
TDN (lb)
Protein (lb)
Deficiency of
Deficiency of
Intake (DM)
From Forage
From Forage
TDN (lb)
CP (lb)
Pasture
29.6
20.9
4.85
----
----
High TDN Hay
24.08
14.9
2.26
1.5
.74
Low TDN Hay
20.70
10.5
2.30
5.9
.70

*********Requirements of1200 lb lactating beef cow: TDN=16.4 lb, CP=3.0 lb********

Clearly, the low qualityhay will require more supplementation or our example cow will sacrifice bodycondition to maintain production. If you have different cuttings or types ofhay to feed, I recommend getting them tested, so better quality hay can betargeted to those groups that need it most. CFC field sales people can takesamples of your hay and send to the lab for analysis (lab cost $20-40/sample).I can help with recommendations once the forage has been tested.