Anytime that I walk through a dairy barn, I walk in front of the feed bunk and usually watch the cows defecate. Their fresh cow pies reflect on how well their milking diet is being consumed and digested. If something is out of line, manure consistency and content warn me almost immediately. So then I take a closer look at the TMR in front of me. I take a sample for analysis and review the barn’s feeding program. From this valuable information, I can take the best course of action in developing a well-balanced diet and get the milking cows back on track.
On any given day, a 600-kg milk cow excretes about 70 kg of manure which contains digested and undigested feed that passes through rumen and the rest of the gastrointestinal tract. It also contains a mixture of digested rumen microbes, rumen fluid, bile and other digestive juices together with large volumes of drinking and recycled body-tissue water. Of the 45-50 kg of “as is” feed (23-27 kg, dmi) they’ve consumed, lactating dairy cows excrete up to 90 per cent of it.
The consistency of each of these cow pies is one of the best indicators of digestion status in dairy cattle. It is dependent upon feed type, nutrient and fibre density, water intake and diet rate of passage. Normal manure consistency should be porridge-like and should produce a slightly dome-shaped pile when the animal defecates. On the other hand, loose manure ranges from slightly formless manure to extreme water-like diarrhea. At the other end of the scale, thick manure is firm, may be dried out and may make tall cowpies.
In the latter case of loose manure, most of its nutritional origins start with dairy diets that are not well-balanced. It often affects cows that are fed lots of forage soluble-protein or diets that do not contain enough effective forage-fibre (that produces a good “forage fibre mat” in the rumen), which is necessary for optimum feed fermentation by the resident rumenal microbes. Other cases of loose manure tend to be far more serious. For example, subclinical acidosis (SARA) may cause loose manure with gas bubbles and is associated with digestive upsets for each suffering cow.
A closer look at manure
Just as manure consistency tells me on how well the lactation diet is digested, the actual makeup of a common cow pie is also very informative. It should contain only large amounts of digested forage and grain particles with the majority of processed forage-fibre no greater than 0.5 inch, and very little escaped grain. In contrast, a cow pie that is littered with long-stem fibre or large amounts of grain might be signal of inadequate effective-forage fibre, unprocessed added grain, or even extremely mature forage in the diet.
The accompanying table is a cross-section of these types of manure that I have encountered in many dairy barns. I classified manure types into general consistency, a closer exam as well as respective corrective action to return less-than-perfect manure, back into a desired and natural porridge-like state:
Notably, each of these corrective actions are based upon three well-proven and mainstream diet recommendations, which I always implement in my own well-balanced lactation feeding programs for dairy cows:
The TMR contains 28 per cent NDF and 75 per cent of this NDF comes from forage sources or equivalent sources (21-22 per cent eNDF)
Forages are chopped at a cut length of 0.5 inch to provide 15-20 per cent of these particles being over 1.5 inches long.
Limit dietary non-fibre carbohydrates (NFC) to 38-40 per cent, with starch limits of 25-30 per cent of the dm diet.
A few years ago, I was visiting a 150-cow dairy and many of the milking cows had diarrhea. I tripped and almost did a face-plant in a pool of loose manure. It was a good thing that I caught myself at the last minute, because I was able to reformulate the cows’ lactation TMR based upon these three rules. Within a few days, their manure become firmer and allowed them to put more milk in the bulk tank.