University of Illinois Extension dairy specialist Mike Hutjens advocates using the following four sets of numbers to evaluate the effectiveness of ration changes and overall herd management:
1. Milk urea nitrogen (MUN). Hutjens likes to see MUN values of 8-12 milligrams/deciliter. Higher numbers indicate that a cow is eating more protein than she can use; lower numbers likely mean she isn’t getting enough protein. Most dairy farmers receive bulk tank MUN values on each pick-up. Tracking these weekly is recommended as levels will vary plus or minus three units.
“I also recommend testing MUN via DHI to see group variation (parity – first, second and third-plus lactation), days in milk (less than 100, 100-200 and more than 200 days), and milk yield (less than 50, 50-75 and more than 75 lbs).”
2. Protein and fat levels. “If your numbers for these components are below breed average, it may reflect a rumen problem or nutrient shortage,” Hutjens notes. “And you’ll get a lower price for your milk. If components are above breed-average, milk value per 100 lbs of milk produced increases.”
3. Manure scores. Hutjens likes to see manure scores of 2.5 for fresh cows, 3.0 for lactating cows and 3.5 for dry cows on a five-point scale. He notes that ration forage levels, physical form of the forage, starch level, feed passage rate, excessive dry matter intake, high mineral intake and protein level and form can all impact scores.
He recommends scoring once a month, more frequently if scores are too low (less than 2.5), ration changes occur (adding new corn silage or haylage), feed quality changes or there’s a mold challenge.
4. Feed benchmarks. Hutjens advises comparing your cows’ performance against industry benchmarks to get a better idea of whether the ration you’re feeding is getting the job done or needs some fine-tuning.
For example, tracking feed efficiency will tell you how well your cows are converting feed to milk and milk components. He recommends setting a target for the herd of 1.4-1.6 (higher for early lactation cows).
Feed cost per pound of dry matter will offer clues about whether you’ve selected the right ingredients, the quality of the forages included in the ration and the value of purchased feed. A good benchmark is 9-10¢ (higher for Jersey and high-producing Holstein herds).
Feed cost per 100 lbs of milk will help you analyze feed costs and milk yield. Depending on the region of the U.S., a good target is $5.50-6.50, says Hutjens.