Dairy Notes
Short notes on the terms that appear throughout the library. Each one is a few paragraphs long and links to the heading where the subject is covered in depth.
AcidosisTwo types of acidosis are recognized: acute and subacute. Acute acidosis is less common but more severe. Affected animals are depressed, off-feed,…Original noteBody condition score (BCS)Body condition scoring is a visual and hands-on estimate of body fat reserves, made at the loin, hooks, pins and tail head. In North America it is…Added 2026Colostrum and passive transferA calf is born with almost no circulating antibodies and depends on colostrum for them. The gut can absorb antibodies intact only for roughly the…Added 2026Dietary cation-anion difference (DCAD)DCAD expresses the balance between the main positively and negatively charged minerals in a ration, most often calculated as (sodium + potassium)…Added 2026Dry matter intake (DMI)Dry matter intake is the weight of feed a cow eats once its water has been subtracted. Rations are balanced on a dry matter basis because moisture…Added 2026Dry periodThe dry period is the rest between lactations, during which the udder tissue is renewed. Sixty days has long been the standard length. It is commonly…Added 2026Feed efficiencyFeed efficiency in a dairy herd is the weight of milk produced per unit of dry matter eaten. To compare herds, milk is first corrected to a standard…Added 2026KetosisKetosis is an excess of ketone bodies in blood, milk and urine, caused by heavy mobilisation of body fat when energy intake does not meet demand.…Added 2026LaminitisLaminitis is a disturbance of the tissue that produces hoof horn. In dairy cows the subclinical form is the usual one, showing weeks later as sole…Added 2026Milk fat depression and CLAMilk fat depression is a fall in milk fat content, often sharp, while milk volume and protein are unchanged. It occurs when unsaturated fats are…Added 2026Milk fever (hypocalcemia)Milk fever is low blood calcium at or soon after calving, when the sudden demand of colostrum and milk outruns the cow’s ability to draw calcium from…Added 2026Milk letdownMilk letdown is the reflex that moves milk from the alveoli, where it is made, into the ducts and cistern where it can be removed. Touch on the teats…Added 2026Negative energy balance (NEBAL)A cow is in negative energy balance when the energy leaving in milk and used for maintenance is greater than the energy she eats. Nearly every cow is…Added 2026pHpH is an indication of acidity or alkalinity, normally measured with a pH meter. When absolute accuracy is not required, colorimetric pH papers are…Original notePhysically effective fibre (peNDF)Physically effective fibre is the portion of the fibre in a ration that is long enough to make a cow chew. Chewing produces saliva, saliva carries…Added 2026Somatic cell count (SCC)Somatic cells in milk are mostly white blood cells that enter the udder in response to infection. Their concentration, in cells per millilitre, is…Added 2026Subacute ruminal acidosis (SARA)SARA describes repeated bouts of low rumen pH that are not severe enough to make a cow visibly ill. A common working definition is rumen pH below…Added 2026Total mixed ration (TMR)A total mixed ration combines forages, grains, protein feeds, minerals and vitamins into a single mix so that every mouthful has the same…Added 2026Transition periodThe transition period runs from about three weeks before calving to three weeks after. In that time the cow ends one pregnancy, begins lactation and…Added 2026Volatile fatty acids (VFA)Volatile fatty acids are the main end products of fermentation in the rumen and supply most of the energy a cow uses. The three that matter most are…Added 2026