Useful Terms
(ADF) Acid Detergent Fibre
A chemical measure of the amount of cellulose and lignin in a ration. Low acid detergent fibre levels are typically associated with improved digestibility in forages.
(ADG) Average Daily Gain (in kilograms)
The average amount of liveweight gain per day from lean tissue and skeletal growth.
(ADP) Apparent Digestible Protein
The measure used to estimate metabolisable protein requirement and supply for young calves up to 100kg liveweight.
(ADICP) Acid Detergent Insoluble Crude Protein
The portion of protein within an ingredient that is totally indigestible throughout the entire gastro intestinal tract. Often associated with heat treated products and very mature forages.
(AF) As Fed
Fresh weight of a ration as offered to the animal.
(APC) Average Pasture Cover
(BCS) Body Condition Score
Indicates the amount of body fat that a mature animal has been able to maintain or accumulate at any given point in time.
(CMR) Calf Milk Replacer
(CP) Crude Protein
Calculated from the total amount of nitrogen in a ration (nitrogen x 6.25). Crude protein (as the name implies) gives no indication as to the quality of protein supplied, solubility, site of digestion or total digestibility.
(DCAD) Dietary Cation-Anion Difference
The total balance of cations and anions in a feed. Measured in milli equivalents per kg DM.
(DDG) Dried Distillers Grain
A by-product of ethanol production that is a highly palatable component of stock rations.
(DM) Dry Matter
A standard measure of moisture content in all rations. Nutrient analysis reported on a dry matter basis is higher than that reported on an as fed basis. Care should be taken to observe on what basis nutrient analysis is reported.
(EAA) Essential Amino Acids
The amino acids required by a cow for milk production, especially milk protein, muscle/tissue regeneration and foetal development. Essential amino acids can come from the rumen microbes washing out of the rumen or from rumen undegradable protein in the ration.
(HOT) Hepatic Oxidation Theory
Describes metabolic feedback mechanisms that have an over-riding influence on dry matter intake during the transition period – final 4 weeks of gestation and first 4 weeks of lactation. It explains the relationship between fuels that are oxidised in the ruminant liver with the firing rate of the vagus nerve, which is connected to the hypothalamus, or feeding behaviour processing site of the brain.
(IgG) Immunoglobulin G
An antibody isotype that calves receive via colostrum feeding. Calves require IgG to develop their own passive immunity in the first days of life.
(LWT) Liveweight
In kilograms
(MJ ME) Mega Joules of Metabolisable Energy
A broad indication of energy required by a cow for maintenance, activity, thermo-regulation, milk production, weight gain and growth. Also used to report estimated energy density of rations on offer, in which it does have some limitations as it does not indicate the type of energy, site of digestion or fermentation characteristics of a ration.
(MCP) Microbial Crude Protein
Essentially rumen bugs that flow out of the rumen and provide a supply of metabolisable protein to the cow. Microbial crude protein is an outstanding source of amino acids to support milk production, lean tissue growth and recovery.
(MP) Metabolisable Protein
The supply of total amino acids to the intestines from microbial crude protein synthesised by the rumen bugs from rumen degradable protein and fermentable energy supply that flows out of the rumen, combined with the digestible rumen undegraded protein from the ration. This combination of MCP and digestible RUP forms the total amount of metabolisable protein that is available for the cow to use for maintenance, pregnancy, milk production and growth.
(MUN) Milk Urea Nitrogen
Indicative of excess soluble protein that has been converted to urea at the liver.
(NDF) Neutral Detergent Fibre
The total amount of cellulose, hemicellulose and lignin found in a ration. Essentially, this is the cell wall material within a ration, particularly forages that has the potential to be digested for energy. Neutral detergent fibre digestibility is a key indicator of forage quality, with higher neutral detergent fibre digestibility being more desirable.
(NE) Net Energy
The rate of efficiency with which calves are able to convert metabolisable energy for a specific function, such as maintenance or growth.
(NEB) Negative Energy Balance
Is any period of time when the energy requirements of a cow exceed the energy available to her via the ration and so she gives up body fat to meet energy requirements. Periods of NEB can be induced either by stage of lactation (eg. late gestation and fresh cows) or inadequate nutrient supply relative to milk solids output.
(NFC) Non Fibre Carbohydrate
Carbohydrates that are not bound to cell wall material and therefore are readily available for fermentation. Starch and sugars are major sources of non fibre carbohydrate. Often calculated by the equation:
100 - NDF% - CP% - Fat% - Ash% (total minerals)
(ORT) Oral Rehydration Therapy
The oral administration of water, electrolytes, glucose and specific amino acids for the replenishment of lost body fluids and energy in dehydrated calves.
(PEF) Physically Effective Fibre (forages greater than 50mm in length)
Looks at the physical properties of fibre on offer and not just chemical measures alone, as this effects chewing behavior and rate of passage (neutral detergent fibre and acid detergent fibre).
(PEM) Polioencephalomalacia
Swelling of the brain.
(RDP) Rumen Degradable Protein
The portion of protein in a ration that is available for degradation and utilisation by the rumen bugs as a source of nitrogen.
(RDS) Rumen Degradable Starch
The portion of starch that is more readily fermentable and provides a source of energy to the rumen bugs. Barley, wheat and products such as tapioca are high in rumen degradable starch. The way grains are processed also influences rate of fermentation and rumen degradablen starch percentage of total starch.
(RES) Rumen Escape Starch
Starch that escapes fermentation in the rumen, escaping utilisation by the rumen bugs and passing through to the small intestine for metabolism. Because it escapes a biological process, there is a higher conversion of rumen escape starch to blood glucose than for rumen degradable starch. Maize grain is high in rumen escape starch due to a combination of physical characteristics and rate of passage through the rumen. Higher levels of faecal starch will be observed if maize grain processing is inadequate.
(RUP) Rumen Undegraded Protein
The portion of protein in a feed that escapes the action of the rumen bugs, either by molecular structure or fast rate of passage and is Undegraded when it reaches the intestines where it is absorbed as specific amino acids. Not all RUP is digestible, so RUP digestibility should be considered when selecting protein sources.
(SARA) Sub-Acute Ruminal Acidosis
Occurs when volatile fatty acids accumulate faster than they can be absorbed across the rumen wall into the blood stream.
(VFA) Volatile Fatty Acids
These are the organic acids which are the end product of rumen fermentation. Major volatile fatty acids produced are acetate, propionate and butyrate. Of these, propionate is specifically a glucose precursor.