This common summer annual forage mistake has forage quality implications.

Dr. Calvin Trostle, Extension Agronomy/TAMU Dept. of Soil & Crop Sciences, Lubbock, (806) 746-6101, ctrostle@ag.tamu.edu

December  2023

What do you observe in this recent sorghum/sudan field from Terry County, Texas?  If you showed this to a local forage grower or cattle raiser, what would you say?

Fig. 1.  Grazing of sorghum/sudan where cattle were turned in to graze much too late or at too-low stocking rate.  Forage is headed out, cattle are eating mostly just leaves, and return on expenses and farmer effort is low. (Calvin Trostle, Terry Co., TX)

This was a dryland field where rainfall had been generous and growth exceptional.  This makes the observed status especially galling as the farmer wasted a great opportunity for a fantastic crop of any kind where drought conditions prevail much of the time.

What happened here?  It appears to me the grower likely turned the cattle into the field much too late.  I would guess this forage was already 5 to 6’ tall.  If this was not the case (cattle were released on shorter plants) then the stocking rate was too low to consume the daily growth of forage.

The result is grain in the heads, stalks the cattle don’t want to eat (possibly even if it is brown mid-rid, or BMR; refer to 07July2023 TAM-AAMM), and plants that grew well enough some of the leave are above the reach of the cattle.

These factors have unfortunate implications for the farmer—and the cattle.  The farmer has lost a great opportunity to use ample forage production for economic return in beef cattle maintenance and preferably weight gain (the best value is for growing stockers rather than cows).  Second, animals are receiving lower quality forage.  This translates to reduced animal performance.  I will address the changes in sorghum/sudan forage quality with increasing growth stage with time in a future update.  (What do you think those charts & tables look like?)

Good Management in Sorghum/Sudan Grazing

A general guideline for sorghum/sudan grazing is to release cattle into the forage at ~24” tall.  Forage is well established.  Cattle won’t pull plants out of the ground when they graze.  Forage quality is surprisingly high.  Sufficient cattle numbers or lbs. animal weight per acre (500 lbs./A?) will:

• Match the growth rate of production of the forage for long-term grazing through the season, or…
• Exceed the growth rate of forage production, graze down the field, then cattle are removed to return later to graze on regrowth.
• The vitality of the forage is maintained by ensuring that excessive grazing is not permitted—the field is not grubbed down—so that vigorous regrowth may occur. (This is driven by the activation of tiller buds, refer to 06June2023 TAM-AMM.)

My First ‘Bamboo Forage Forest’

On our Kansas family farm, we had small lots where we overwintered stockers.  After cattle went to pasture Dad would drill Dekalb “Sudax” SX-17 haygrazer in the lots for forage.  But we never turned any cattle in until after prairie grazing waned in the fall.  Thus, forage was headed out, stalks were 8’ tall/stiff/unpalatable, and some forage was above the reach of the cattle.  We made several forage mistakes.  Frankly we didn’t know better.  The cattle wouldn’t eat anything but leaves.  We even thought “grain is good” in our haygrazer!  (There should never be grain in grazing or hayed sorghum/sudan.)  But if the cattle did eat the heads there was reduced nutritive value because the hardened kernels passed through the rumen largely undigested.

In hindsight, we didn’t recognize we should have ether 1) put a modest stocking rate into the pens for summer-long grazing, or 2) brought in a high number of stockers to graze down sorghum/sudan for about two weeks, then allow for regrowth and repeat grazing.

Suggestions for Field Crop Workers

Helping Texas forage growers improve their understanding of good forage production, grazing, and haying practices is a valuable mission of Texas A&M AgriLife Extension and our clientele.  Whatever your role, consider these opportunities in your area, regardless of the type of forage grown:

• Observe grazing practices on sorghum/sudan, wheat pasture, bermudagrass, and even native range for possible improvements in management.
• Visit with producers about what you see (introduce yourself if needed). First, ask about their forage goals.  Then offer suggestions where there is room for possible improvement.
• Become more aware of animal nutritional requirements based on their stage of growth (younger animals vs. reproductive age).
• Team up with Texas A&M AgriLife to offer informative programming in your area for optimizing forage production and value.