Dairy calves that develop rough hair coats, appear depressed or less thrifty and have poor growth may be suffering from a condition called "rumen drinking," said Dr. Auburn Moyer, dairy technical support with Hubbard Feeds, in a recent "Dairy Soultions" newsletter.
Rumen drinking is caused by a failure of the reticular groove reflex, resulting in rumen acidosis in calves on a liquid diet, Moyer said. When the reticular groove partially or completely fails to close, milk spills into the rumen and is fermented to lactic acid. This acid formation is not desired and decreases the pH in the rumen, causing inflammation in the lining of the stomach.
Moyer noted that a number of conditions can make calves more susceptible to rumen drinking caused by failure of the esophageal groove to close, including:
1. Neonatal diarrhea;
2. Irregular feeding times;
3. Low-quality milk replacer;
4. Feeding milk or milk replacer at too cold of a temperature, and
5. Drinking from an open bucket or gulping milk.
Signs of rumen acidosis due to rumen drinking include poor intake, dehydration due to diarrhea, a bloated, distended abdomen, hair loss and lethargy.
Prevention is key, because the prognosis of chronically affected calves is poor, Moyer said. Typically, if treating the primary disease is successful, the groove will regain normal function.
Management factors that support prevention are: rapid detection and treatment of sick calves due to other illnesses, feeding milk/milk replacer at the right temperature, feeding calves at the same time every day and limiting environmental stressors. Repetitively force-feeding/tubing calves that do not want to eat can cause rumen acidosis or worsen the situation by providing a substrate for further fermentation, Moyer pointed out.
Calves with suspected rumen drinking should be fed smaller and more frequent meals until symptoms resolve.
The early ensiling period is critical to silage quality and stability because this is when newly harvested forage begins the transition to stable silage.
Driving quick, efficient fermentation is essential to maximizing dry matter recovery and preventing spoilage, according to Dr. Renato Schmidt, forage products specialist with Lallemand Animal Nutrition.
"A fast, efficient, front-end fermentation will help stabilize the silage environment and reduce yeast growth, which is the major cause of silage heating," Schmidt said.
Ensiling involves acidifying, or "pickling," the crop, and fermentation is an anaerobic process involving the conversion of sugars into organic acids, with lactic acid being the main driver of a rapid drop in pH. These acids are mainly produced by lactic acid bacteria (LAB), which are present on the crop in variable numbers naturally but in guaranteed quantities if using a quality inoculant.
After the silo has been filled and sealed, the forage contains entrapped oxygen. This oxygen is reduced by respiration of the plant material and by growth of microbes such as yeasts, molds, enterobacteria and LAB. During this stage, the pH will start to fall if the LAB population is sufficient, Schmidt noted.
Once the silage becomes anaerobic, the ensiling fermentation and conversion of forage to silage begins. For successful fermentation, the pH should be rapidly reduced until it is below 5.0 and should continue until the pH is low enough to stabilize the silage.
"A slow initial fermentation can allow the growth of spoilage microbes," Schmidt said. "Rapid production of lactic acid is very important to maximize dry matter and digestible nutrient recovery. Using a quality inoculant and good application technology can help ensure the population of LAB is sufficient to drive a fast, efficient, front-end fermentation through the total forage mass."
Quality forage inoculants can help ensure that silage hits the correct pH targets and acid profile to promote stability and maximize dry matter and nutrient preservation, he said, adding that specific LAB are more suited to the task than others.
"The early ensiling period is a critical time in silage production," Schmidt explained. "Using a proven inoculant can help ensure the right LAB are present to reach a stable pH."