When Drought-stressed Pastures Look Dormant in July

When Drought-stressed Pastures Look Dormant in July
Professor, Department of Animal Science
Cattle in pasture.

Julie Laird/realagstock

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As the drought that has plagued the western U.S. since 2020 hangs on, much of Nebraska is currently experiencing moderate to severe drought. July tends to be a busy time for production cows, resulting in high nutrient demands, which further exacerbates the limitations of drought-stricken grass.

Lactating cows grazing limited forage resources may struggle to select a diet that will also support rebreeding. Cows calving in April and May must be bred in July and August. When rainfall is adequate and proper stocking density is used, the grass in July and August is typically adequate to support the needs of the lactating and cycling cow. However, in a severe drought, such as this year, not only is there risk of overgrazing and damaging the pastures, there is also a risk of having a high percentage of open cows when cows are checked in the fall.

Options for Supplementing Pairs on Pasture

Supplementing on pasture can help stretch the grass and increase the nutrient content of the diet, but must be done with caution. Supplementing a small amount (2-3 lb/pair) of distillers grains will not decrease forage intake, and may actually improve utilization and therefore increase low-quality forage intake. Pairs would likely have to be supplemented 0.6% BW (dry matter basis (DM)) to have forage replacement value. While this can replace some forage intake, it is likely only going to be 10-12%.

University of Nebraska research has shown mixing roughage and wet distillers can provide a higher rate of forage replacement than distillers alone. When wet distillers grains and ground wheat straw were mixed at a ratio of 30:70, respectively (DM), the forage replacement value was almost 1:1 DM. When blends of 50:50 were used, or hay rather than residue was used, less forage replacement was achieved. Overall, the average forage replacement was 44%. This method of forage replacement can stretch the time cows are out on the pasture, but because forage replacement is less than 100%, can still result in overgrazing. Producers will want to monitor pastures closely for signs of overgrazing.

Feeding on Pasture instead of in Confinement

Although feeding in confinement might be simpler for some producers — there are several reasons or time points — producers may prefer to feed almost a complete diet on pasture. Some producers may not be set up for confinement feeding that will allow a small calf access to bunks and water, or that can even keep a small calf confined. Therefore, feeding on pasture where pasture bunks can be accessed from both sides, or the diet can be fed on the ground, may be a better option.

During a drought, early weaning is often employed to reduce forage intake on a pasture. However, weaning calves younger than 90 days of age can be labor intensive if calves are retained, and less popular with a buyer than an older calf. An April-born calf is only 60 days old in July and, therefore, for some producers, feeding pairs on the pasture may be the best option until the calf is 90-120 days of age. This also reduces the risk of pathogen loads for the very young calf and gives them an opportunity to graze some forage as well. 

Points to Ponder

Late spring calving cows are in the breeding season now with a bad combination of high nutritional demands and drought-stricken pastures in many locations. For producers who have access to wet distillers grains and crop residues, feeding on pasture may be an option to stretch pastures, improve body condition on cows through the breeding season, increase options for calves, and delay confinement feeding. However, the cost of feed needs to be evaluated against the value of herd reduction, especially when commodity prices and delivery costs are high.