FORMULA SHELF
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The arithmetic behind the work: what to measure, what to type in, and what the answer comes out as. Every formula says what the symbols mean and gives a worked example, so you can check it against a job you have already done.
SHELVES
Health
8 formulas
For any medicine given by weight. First work out the animal's weight, then multiply, then convert to millilitres using the concentration on the label. Always confirm the dose with your vet before the first use.
A drug at 10 mg/kg for a 400 kg cow = 4,000 mg, which is 4 mL of a 1,000 mg/mL solution.
To plan the yard, the lambing shed, the farrowing crate and the calving pen. Add a few days to the average for a first-time animal, because first pregnancies run long.
A sow served on 1 March is due around 23 June.
A rough guide for people, and a reminder that a weight without a condition score is only half a judgement. Use body condition scoring for stock, and the tape for pigs.
70 kg at 1.75 m gives a BMI of about 23.
Almost every medicine error is a unit error. Learn the ladder by heart and write the unit next to every number you copy off a label.
2.5 g = 2,500 mg = 2,500,000 micrograms.
Sunken eyes, tight skin and a tacky mouth in a calf or a dog mean a percentage of body weight has gone. A 5% loss in a 40 kg calf is 2 L to put back.
A 40 kg calf 5% dehydrated: (40 x 5) / 10 = 2 L short.
Feed energy is quoted in megajoules of net energy, and food labels in kilocalories. The conversion lets you compare the two. A megajoule is 239 kcal.
10 MJ of net energy = 2,390 kcal.
Convenience only. Double-check the result against the worked example or a second method before you use it.
The starting point for how much water or IV fluid an animal needs. Add losses for fever, heat, exercise and any diarrhoea. A cow drinking less than this is a cow that will go down.
A 500 kg cow needs about 25 L a day.
To check a ration against a feed table. Growers and lactating stock need more protein than dry stock, and the tables are always in digestible protein.
A 600 kg lactating cow at 1.2 g/kg needs 720 g of digestible protein a day.
SOURCES & PROVENANCE
1 listed
This page is an AI-organised index. The label means the grouping and cross-links were compiled with AI; the information itself comes from the public-domain books, reports and manuals listed below. Open any source to read the local copy or follow the link to the original publication.