Quick answers for everyday herd decisions.
Five small calculators for the questions that come up every week: how much water the herd needs, how to mix hay and supplement, how much dewormer to buy and when cattle can be sold, how fast calves are gaining, and how the herd did this year. Every number comes from a public extension source or a product label, listed under each tool.
Water: how much the herd drinks
Other Metals and Minerals (Table 9-5)
Result
- Total dissolved solids under 1,000 ppm are safe; up to 3,000 ppm is generally safe; avoid 5,000 ppm or more for pregnant or nursing cows; never use water at 7,000 ppm or more.
- Keep water within about 650–1,000 feet of every part of the pasture for even grazing.
Source: Mississippi State University Extension, Beef Cattle Water Requirements and Source Management (P2490, Karisch, Parish & Rhinehart), tables adapted from NRC Nutrient Requirements of Beef Cattle (2000); the same Winchester & Morris (1956) values are Table 9-1 of NASEM Nutrient Requirements of Beef Cattle, 8th rev. ed. (2016). The calculator interpolates between the published temperatures and weights. Water quality limits: NASEM (2016), Chapter 9, Tables 9-2 to 9-5 and text on sulfate. Arsenic uses 0.3 ppm, the cattle limit Argentine water labs report; published guidelines range from 0.05 (NRC 2001) to 0.2 (NASEM 2021, dairy) and 0.5 ppm (ANZECC 2000, Australia).
Ration Mix: two feeds to hit a target
Enter nutrients on a dry-matter basis (from a forage test or the feed tag divided by its dry matter). The tool finds how much of each feed hits your target — the Pearson square.
Result
Sources: University of Arkansas Extension, Beef Cattle Nutrition Series Part 4: Formulating Rations (FSA3080, Gadberry) for the Pearson square on a dry-matter basis; Supplementation Strategies for Beef Cattle (B-6067, McCollum) for how supplements change forage intake.
Dewormer: dose, bottles and sale date
Result
Always read and follow the label on the product you buy — formulations and withdrawal times differ between brands and can change. Extra-label use needs a veterinarian.
Weight gain: are they on pace?
Result
- Behind pace on grass? An ionophore in the supplement or mineral (monensin, lasalocid) raised gain about 10–12% in growing cattle on forage without changing how much they ate.
- A growth implant adds about 12% more gain on pasture; implant plus monensin together added about 22% (steers on wheat pasture). Check the label for the animal class.
- Calves that were held back and then get good feed usually gain faster for about 60–90 days (compensatory gain).
Source (gain): NASEM Nutrient Requirements of Beef Cattle, 8th rev. ed. (2016), Chapter 14 (Bretschneider et al., 2008; Beck et al., 2014) and Chapter 11 (compensatory gain).
Source (shrink): Oklahoma State University Extension, Managing Shrink and Weighing Conditions in Beef Cattle (AFS-3257): 2–3% from gathering and sorting, about 3% from loading and a short haul, roughly 1% an hour for the first 3–4 hours on a truck.
Herd Year: reproduction and head count
Result
Source: Standardized Performance Analysis (SPA) definitions, as used in the beef cattle decision aids (SPA Reproduction: Critical Dates, Data and Calculations). Pregnancy and weaning percentages are based on exposed females, the SPA standard; pounds weaned per exposed female = weaning % × average weaning weight.