Still Prime, Wait Still

Grass and mixed hay were still in the target zone for dairy quality at sampling this week, although we would expect it to advance past prime next week. Legume quality is reaching dairy quality stage and will be ready to harvest this week. It is also go time for harvesting hay for growing beef. Producers looking for forage for mature beef cows, lactating or dry, should wait at least another week.

Estimated days from 5/24 to reach target quality for classes of cattle

Grasses rapidly grew taller this week as stem elongation kicked, with some fields gaining 20 inches or more, while legumes grew by as much as a foot.   Orchardgrass and other earlier maturing grasses are headed this week, legumes are approaching bud stage.  After grasses are fully headed, they will reach their full height, and fiber (aNDFom) will only go up slowly, but NDF digestibility will trend down more rapidly.  Energy (TDN) decreases as cell walls thicken and become more “woody”.

The Table below has each sample location, listed by Town and elevation, and lists the species sampled, average height, Neutral Detergent Fiber (NDF), Neutral Detergent Fiber Digestibility (NDFD), and Total Digestible Nutrients (TDN). We have sampled grass, legume and mixed legume/grass fields across the county and at elevations from 1070 to 2100 feet. Look for locations with similar forage type and elevation to your farm.

We report several measures of forage quality. Different types and groups of cattle have different demands and each measure tells a slightly different story. If harvesting for dairy forage, we suggest harvesting based on NDF, for beef choose an appropriate TDN target or the animals you will be feeding

NDF – Neutral Detergent Fiber is a measure of the structural fiber in a feed sample. NDF correlates well with how much forage a cow can eat (gut fill). Earlier cut hay = lower NDF = higher dry matter intake = higher performance.

NDF goals for Dairy Cattle Forage: Grass hay and silage – 48 – 55%, MMG hay & silage – 40 – 50%, MML hay & silage – 38 – 45%, Legume hay & silage – 36 – 42%

NDFD – NDF Digestibility As forage plants mature, the fiber percentage increases, and at the same time the digestibility of the fiber decreases. NDFD measures the digestibility of fiber by rumen fluid. We report 24hr NDFD as an indicator of forage digestibility. Higher digestibility = more energy available from a forage.  Grasses inherently have a higher NDF digestibility than legumes.

TDN – Total Digestible Nutrients The sum of the digestible fiber, protein, lipid, and carbohydrate components. TDN is a measure of energy available from forage and is related to digestible energy. TDN is useful for beef cow rations that are primarily forage. Higher TDN values indicate higher energy available, cattle groups with higher energy demands require higher TDN intakes.