Healthy, Productive Cows
Need Healthy Rumens
By: Donna Amaral-Phillips, Ph.D.
Do your cows display any or all of the following symptoms?
 Disappointing milk production - In particular, early lactation cows do not peak as
high as expected.
 Decreased cud chewing or rumination- Cows should spend approximately 12 hours
daily resting and the majority of this time they should be chewing their cud. When
you walk through the barn, more than 60% of the cows not eating should be
chewing their cud.
 Sore-footed or lame cows- Specifically, has your hoof trimmer or veterinarian said
that your cows have laminitis or are foundered. These symptoms may occur weeks
or months after the events causing the initial problem.
 “Hardship grooves” or ridges on hooves. Like our fingernails, a cow’s hoof grows
downward from the coronary band (where the skin/hair of the leg meets the hoof) at
approximately 0.25 inch per month. With nutritional mismanagement or disease, a
depression or disruption in the smoothness of the hoof wall occurs parallel to the
coronary band. By measuring how far down the “hardship groove” has migrated,
one can estimate when the incident occurred.
 Wide fluctuation in feed intake for individual cows- The average feed intake for the
herd may remain relatively constant from day-to-day but individual cows may have
widely fluctuations in feed intake.
 More than 10% of the cows in the herd have depressed butterfat tests- Milk fat
inversions occur when the butterfat is more than 0.2 units below the milk protein
test. No cows in the herd should have a butterfat percent one full point below the
breed average. (The Holstein breed averages 3.67% butterfat - 1999 data.)
 Low body condition - Cows are thinner than diet formulation would suggest.
 Digestive upsets- Feces in the herd varying from normal to very loose.
The symptoms mentioned previously relate to a syndrome known as subclinical ruminal
acidosis. Subclinical ruminal acidosis is a fermentation disorder in the rumen usually
characterized by a lower than normal rumen pH (less than 5.5). This syndrome results in a
number of vague symptoms which often are hard to pin point. Cows are not extremely sick
and do not usually die but just do not eat and perform as well as expected. In one Florida
herd, scientists estimated that each episode of acidosis cost the producer $208 in decreased
milk production, early culling and costs associated with treatment. As always, we want to
prevent problems rather than deal with disasters.
Management Factors Which Increase Risk for Acidosis
The top five causes or contributing factors which increase the risk for subclinical acidosis are
listed below.
1st Inadequate forage particle size- When cows chew their cuds, they secrete saliva
which buffers the rumen contents. In order to form this cud, cows must be fed forages with
adequate particle size.
Commonly seen: This problem is commonly encountered when silages are chopped too
finely when ensiled or removed from the silo (silo unloader chews up the forage). Also,
forages may be of adequate particle size at harvest but TMR mixers which are run too long
can pulverized forages thus decreasing chewing time and saliva production. Often times, we
see this problem when a farmer gets a new TMR wagon or replaces the augers or knives in
an older mixer.
2nd Transition from dry cow lot into the milking herd- Currently, the
recommended practice is to adjust dry cows to the forages fed to the milking herd three
weeks before a cow or heifer calves. In addition, cows and heifers should be fed a balanced
diet which can contain up to 8 to 10 lbs of grain three weeks prior to calving. These feeding
and management practices help the cow start adjusting to the higher nutrient density of the
ration fed to the milking herd before she calves.
Commonly seen: This problem is seen in dry cows fed hay and a small amount of grain prior
to calving. After calving these cows are fed the milking herd TMR or forages (especially corn
silage-based diets) and as much grain as they can eat after calving. With cows fed in this
fashion, we commonly see acidosis problems specifically in early lactation cows less than 40
days fresh.
Transition problems also can occur when fresh cows receive too much grain too
quickly after calving. This happens when they are allowed unlimited access of grain in the
parlor especially during the first 2 weeks after calving.
3rd Digestibility and starch content of corn silage- When feeding dairy cows, it is
important to remember that we are first feeding the rumen bacteria or bugs that in turn feed
the cow herself. When balancing rations, we want to provide adequate amounts of energy or
starch for bacteria to grow but excessive amounts will decrease their numbers.
Commonly seen: During some growing years and in certain varieties, corn silage is higher in
grain content and contains an acid detergent fiber (ADF) as low as 19% on a dry matter 3
basis. Rations needed to be balanced to take into account this higher starch content and fiber
digestibility. Also, brown midrib corn silage is lower in lignin and has a higher NDF digestibility
than regular corn silage.
4th Too much long hay in TMR which allows cows to sort- Cows will use their
muzzle to sort through a TMR especially when the TMR is too dry or when it contains a large
percentage of longer particles. Generally, the more aggressive eaters select the more
palatable concentrate particles resulting in an unbalanced diet short on effective or rechewable fiber.
Commonly seen: This problem has been observed in herds where 10 lbs of hay or more was
included in the ration especially when lower quality hay was included in the TMR. By watching
the cows, you can observe the sorting behavior and the cows sorting out of the grain and
forages with small particle size. Also if the total ration is too dry, sorting may be more
pronounced in the feed bunk.
5th Inadequate feed management: The key to feed management is to get as much
high-quality, properly balanced feed into cows as possible. The statement that the more feed
a cow eats the more milk she can potentially give is very true especially in early lactation
cows.
Commonly seen: In herds where grain is fed separately from the forages, limited bunk space
and/or an irregular feeding schedule can decrease forage intake especially in the more timid
cows. The timid cows will eat their share of grain in the parlor but will not receive adequate
amounts of forage to balance the starch found in the grain mix. In TMR fed herds, not
monitoring the dry matter or moisture content of the forages changes the amount of forage
fed. Forage intake can decrease and cause acidosis problems.
Educational programs of Kentucky Cooperative Extension serve all people regardless of race, color, age, sex,
religion, disability, or national origin.