Dairynutrient 414 Ruminant Nutrition Dairynutrient 414 Ruminant Nutrition Glossary

A latin word that means "to one's pleasure." In nutrition, ad libitum (abbreviated "ad Lib") refers to feeding management in which animals are fed without restriction. Cows are usually considered fed ad libitum when the refusals (orts) amount to approximately 5 to 10% of what has been offered the day before.

Allometric equations take the general form Y = aM^b, where Y is some biological variable, M is a measure of body size, and b is some scaling exponent. See West et al. (2012) for more details.

The growth of body parts at different rates, resulting in a change of body proportions.

Protein released in the blood that is generated in reaction to a foreign protein (antigen) that has entered the body. Antibodies produce immunity against certain micro-organisms or their toxins.

Desire for food that can be quantify by measuring dry matter intake.

Reproductive procedure by which semen previously collected from sires, packaged in “straws” and frozen in liquid nitrogen is thawed and manually deposited in the uterus of a cow in estrus, in the hope of conception. Artificial insemination is a technology that allows for genetic improvement based on selection and use of superior sires.(see also Timed Artificial Insemination).

Single-cell organisms living either independently or in close association with other living organisms. Often referred to as microbes or microorganisms because of their microscopic size. Some bacteria are beneficial, but others cause infectious diseases.

A measure of protein quality. The percentage of protein in a feed which is not lost in the urine or the feces of the animal. Biological value is a reflection of the balance of amino acids available to the animal after digestion and absorption.

A swelling of the left side of the cow caused by a frothy material which prevents gases of fermentation from being eructed from the rumen. Occurs primarily when cows are grazing certain species of legumes especially, alfalfa. If not treated immediately, bloat can cause death in a matter of hours. More...

(see Parturition)

Any of a group of chemical compounds, including sugars, starches, and cellulose, containing only carbon, hydrogen, and oxygen, with a ratio of hydrogen to oxygen of 2:1.

The part of the metabolism in which metabolites are oxidized for the production of work and heat.

A substance present in small amounts that increases the rate of chemical or biochemical reactions without being consumed in the process.

To crush or grind (food) in the mouth by continued action of the teeth with the help of the tongue (syn to masticate).

The thick and yellowish secretion collected from the mammary gland at the first milking after calving. The colostrum is low in lactose but normally high in total solid (24%). It is rich in fat, proteins and antibodies that help the new born calf to fight infectious diseases. The secretion collected from the second to the eighth milking is referred to as "transition milk" because of it intermediate composition between colostrum and whole milk.

Feedstuffs usually rich in energy and coming from the part of the plant that accumulate nutrient reserves for an embryo (fruits, nuts, seeds and grains). The word concentrate is also used to refer to the mixture of minerals and other supplements used to feed dairy cattle.

A measure of the amount of protein in a feed determined as the amount of nitrogen multiplied by 6.25. The factor 6.25 is the average grams of protein that contains 1 gram of nitrogen. The word "crude" refers to the fact that not all nitrogen in most feed is exclusively in the form of protein. Because most feeds contain non-protein nitrogen (NPN), crude protein generally overestimates the actual protein content of a feed.

A measure of the concentration of matter per unit of volume (e.g., g/l or kg/m3)

The mixture of digestive secretion, bacterial population and feeds undergoing digestion in the gastro-intestinal tract (such as rumen content).

A measure of the proportion of a feed that is digestible. The digestibility of a nutrient is often measured as the difference between the amount of nutrient ingested minus the amount of nutrient excreted in the feces, expressed as a percentage of the nutrient ingested: 100 x (intake - excreted)/intake.

That part of the feed which is not water. It is usually determined by the residual weight of a sample placed for a period of time in a drying oven that removes the water from the sample. Usually, the dry matter content of a feed is expressed as a percentage. For example, an hay of 85% dry matter contains 85 g of dry matter for each 100 g of fresh feed.

A method of expressing the concentration of a nutrient in a feed. For example, a feed containing 12% crude protein on a dry matter basis contains 12 g of protein for each 100 g of feed dry matter

Quantity of dry matter ingested by a cow in a 24 h period. For example, a cow eating 18 kg of grass silage of 33% of dry matter ingest 18 x 0.33 = 6 kg of grass silage dry matter.

A measure of the concentration of energy in a feed or a ration usually expressed as a unit of energy (megacalorie or megajoule) per lb of dry matter or per kg of dry matter.

Method used to select cows which are eligible for hormonal treatment (such as Ovsynch). For example, the enrollment plan may be defined by the voluntary waiting period or a negative pregnancy check.

Membranous tissue, usually in a single layer, composed of closely arranged cells separated by very little intercellular substance. The epithelium forms the lining of the respiratory, intestinal, and urinary tracts and the outer surface of the body.

The removal of a material from an organism. Example of material excreted include tears, urine, feces, sweat and carbon dioxide. Examples of an organism's organs involved in excretion include eyes, bladder, rectum, skins and lungs.

An animal that tests as negative but who is actually positive. The percent of false negative for a test can be calculated as 100 – SENSITIVITY.

An animal that tests as positive but who is actually negative. The percent of false positive for a test can be calculated as 100 – SPECIFICITY.

1. Ester of glycerol and fatty acids. 2. Organic compound containing carbon, hydrogen and oxygen, but as opposed to the carbohydrates, fats have a ratio of hydrogen to oxygen well above 2:1. Fats, as opposed to oils, are solids at room temperature and usually are of animal origin.

A chain of carbon terminated by an acid (carboxyl) group (COOH). Fatty acids with less than 4 carbon units are volatile. Fatty acids with 5 to 20 carbon units are usually found as part of fats and oils.

The transformation of carbohydrates in absence of oxygen by rumen micro flora that produces volatile fatty acids such as acetic acid, propionic acid and butyric acid, and gases such as carbon dioxide (CO2) and methane (CH4).

The unborn young.

Nutrient of low energy density present in large quantities in forages. Fiber is composed of structural carbohydrates (cellulose and hemicellulose) and phenolic compounds. Fiber is important for dairy cows because they stimulate rumination and promote a healthy rumen environment for bacterial growth. However, in large amounts in the diet, fiber may fill the rumen, limit intake of energy and constrain milk production.

Hemicellulose and cellulose that can be quantify by the neutral detergent fiber procedure.

Usually expressed as two percentages. The percentage of ration dry matter that is made up of forage and the percentage of ration dry matter that is composed of concentrates. The two total 100. For example a 50:50 forage to concentrate ratio means that a cow eating 20 kg of dry matter of that ration would eat 10 kg of concentrate dry matter and 10 kg of forage dry matter.

Is a polymer of fructose molecules generally, but not always, found as "carbohydrate storage in cool season grasses (C3 plants). Tall fescue and perennial ryegrass tend to have the highest levels of fructans when compared to other grasses under the same conditions. Fructan is stored in vacuoles inside cells throughout the plant where it is readily available as needed. In some species of grass the lower part of the stem is a carbohydrate storage organ.

A sweet sugar occurring in many fruits and honey.

The stomach and the intestine as a functional unit.

To begin to or to cause to grow (syn to sprout.

An enlargement of the thyroid gland associated with iodine deficiency and visible as a swelling at the front of the neck.

A period of 9 to 24 hours preceding the ovulation during which cows are receptive to bulls and exhibit a typical behavior of mounting other cows or standing when mounted by other cows (or a bull).

A unit of measurement of the amount of biologically active vitamin in a feed or required in a diet.

A condition characterized by a lack of appetite, especially for concentrates and an abnormally high concentration of ketone bodies (e.g., acetone, hydroxy-butyrate) in the blood. Ketosis or acetonemia occurs when the cow mobilizes large amounts of body reserves in early lactation.

A disaccharide composed of a unit of glucose and a unit of galactose. Also known as milk sugar, lactose is produced commercially from whey.

Inflammation of the sensitive vascular tissue of the hoof.

A feed or drugs that will induce bowel movements (defecation) and relieve constipation.

A sedimentary rock, chiefly calcium carbonate (CaCO3), containing variable amounts of magnesium. It is used as building stone, but also as a source of calcium in ration of animals.

Protein coated packages that transport fats in the bloodstream

Any compound that helps to prevent the accumulation of abnormal or excessive amounts of fat in the liver, control blood sugar levels, and enhance fat and carbohydrate metabolism.

A diet that supplies the nutrients required to maintain vital functions (heart beat, respiration) and assure a constant body temperature.

A physiological state in which the animal is neither gaining nor losing weight, performing work or expending nutrients for any type of production.

To grind or crush (food) with or as if with the teeth to prepare it for swallowing and digestion (Syn: Chew).

An infammation of the udder (often caused by a microbial infection) resulting in pain and the secretion of milk with a high count of white blood cells (referred to as somatic cell count).

The mean of a normal distribution is the most likely value (the value that has the lowest probability of being "wrong"). The mean is the best measure of central tendency of a normal distribution. With a normal distribution, approximately one-half of the samples have values lower than the mean and one-half have values higher than the mean.

Refers to all of the changes that nutrients undergo after they are absorbed from the digestive tract. Metabolism is divided into anabolism and catabolism.

A product of metabolism of nutrients.

In ruminant nutrion, metabolizable protein, often abbreviated MP, is the amount of digestible protein that reach the small intestine, which is the source of amino acids absorbed into the blood. The three main sources of MP include rumen undegraded protein (the dietary protein fraction that has not been degraded in the rumen), the microbial (bacterial) protein synthesized in the rumen from the fermentation process, and the endogenous protein (intestinal digestive enzymes and sloughed cells from the gastro-intestinal tract). The latter source is minimal.

Inflammation of the uterus.

To grind, pulverize or break down into smaller particle size in a mill.

Having one digestive cavity (i.e., one stomach).

Morbidity is an incidence of ill health. It is measured in various ways, often by the probability that a randomly selected individual in a population at some date and location would become seriously ill in some period of time. Contrast to mortality.

is incidence of death in a population. It is measured in various ways, often by the probability that a randomly selected individual in a population at some date and location would die in some period of time. Contrast to morbidity.

A cow that has given birth more than once.

The amount of energy in a feed which is available for milk production and body maintenance. Feeds generally are similar in total energy content but vary widely in the proportion of the total energy which is available for maintenance and milk production. The remainder of the energy in the feed is lost in the feces urine, gas belched form the rumen and excess heat production by the cow. In the cow, it takes 0.74 Mcal NEl to produce 1 kg of milk containing 4% fat and the net energy content of most feed range from 0.9 to 2.2 Mcal NEl per kg dry matter.

A measure of the amount of cell wall in a feed determined by a laboratory procedure. Neutral detergent fiber includes cellulose, hemicellulose and lignin.

Carbohydrates that are not part of the neutral detergent fiber, but generally accumulate in the plant as energy reserve (e.g., starch). These carbohydrates usually are more rapidly and more completely digested than the fibrous carbohydrates (syn Non-structural carbohydrate).

Nitrogen that comes from a source other than protein but may be used by a ruminant in the building of protein. NPN sources include compounds such as urea and anhydrous ammonia, which are used in feed formulations for ruminant only.

(see non-fiber carbohydrate).

The chemical substances found in feeds that can be used, and are necessary, for the maintenance, production and health of the animal. The main classes of nutrients are carbohydrates, fats, proteins, minerals, vitamins and water.

This refers to meeting the animal's need of the various classes of nutrients for maintenance, growth, reproduction, lactation and physical work.

Compounds composed of carbon oxygen hydrogen and nitrogen. All living organisms are composed primarily of organic matter. Fats, carbohydrates and proteins are examples of organic compounds.

This is a German word that refers to leftovers of a meal. In dairy nutrition the orts is the amount of feed refused from a daily offering. In dairy nutrition research, orts must be sampled and analyzed in order to calculate with precision the consumption of dry matter and nutrients by the cow. Orts expressed as a percent of dry matter offered is a criteria to determine whether an animal was fed ad libitum (Syn: refusals).

Release of an oocyte (i.e., egg) from a mature follicle. In dairy cows, ovulation occurs 24 to 32 hours after the first standing event of behavioral estrous. Similarly, ovulation occurs 24 to 32 hours after an injection of Gonadotropin Releasing Hormone; (Gn-RH) administered in the presence of a dominant follicle.

The taste and flavor property of a feedstuffs that make them more or less acceptable to be eaten.

1. Small projections on the inner surface of the rumen and the reticulum wall that increase the surface area of absorption of volatile fatty acids and other end-products of bacterial fermentation.

Protuberances at the surface of the tongue that detect the taste of a feed.

The act of giving birth (Syn Calving).

1. At least 2 but not more that 100 amino acids linked together by a peptic bound. 2. Product of pepsin digestion of proteins.

The process by which the chlorophyll of plants converts carbon dioxide and water into simple sugars with the simultaneous release of oxygen.

An organ that develops during pregnancy in female mammals. It lines the uterus and partially envelopes the fetus, to which it is attached by the umbilical cord. Following birth, the placenta, then called the after birth, is normally expelled. The retention of the placenta usually leads to bacterial infection of the uterus called metritis.

To free from coarseness; to refine.

Having more than one digestive cavity; Having a stomach divided into different chambers (e.g., ruminants).

The set of individuals, items, or data from which a statistical sample is taken. In statistical terms, a population is defined as a larger set from which samples are obtained.

Having one or several fetus growing inside the uterus.

Digestive enzyme that breakdown proteins into peptides.

A chain or multiple chains of amino acids (more than 100). Proteins are composed of carbon, oxygen, hydrogen nitrogen (16% on average,found in the form of amino acids) and often sulfur. Proteins have important functions in the body. They are present in all plants and animals and they are essential in the ration of animals. See also Crude Protein.

Most primitive form of life in the animal kingdom composed of only one microscopic cell.

Reversal of the natural direction in which contents flow through a tube or a cavity in the body. During rumination, rumen contents are regurgitated through the esophagus in the mouth for further mastication.

The first two stomachs of a ruminant comprised of the reticulum and the rumen. A microbial population lives in the rumen and enable the cow to digest dietary fiber. The digesta in the rumen and the reticulum is being exchanged once about every 50 to 60 seconds under the influence of a rhythmic cycle of contraction which also results in passage of some digesta from the reticulum into the omasum through the reticulo-omasal orifice.

The second stomach of a ruminant in which folds of the mucous membrane form hexagonal cells. Also called honeycomb stomach. The reticulum is joined to the omasum by the reticulo-omasal orifice.

A deficiency disease resulting from a lack of vitamin D or lack of sunshine exposure, characterized by defective bone growth.

Part of the plant, usually under ground that maintain the plant, withdraw water and other nutrient from the soil, and sometimes accumulate reserves of nutrients.

The movement of a material from one place to another. Secretion is often required to move a material to the place where it can be excreted. Examples of materials secreted include all materials excreted (see Excretion above), plus enzymes, hormones and saliva. The organs that play a role in secretion include all those involved in excretion, plus the digestive glands like salivary glands, pancreas, liver and gallbladder and endocrine glands like the thyroid gland, pituitary gland, and ovaries and testes.

The probability that a test is positive, given that the animal has the disease (See also specificity).

(a) Any of the cells of a plant or animal except the reproductive cells. (b) Milk somatic cells are primarily leukocytes (white blood cells) and some epithelial cells shed from the lining of the mammary gland. The leukocytes are derived from blood and consist of macrophages, lymphocytes, and polymorphonuclear cells, primarily neutrophils (PMN). Normal milk does contain somatic cells, and the concentration of these cells is almost always less than 100,000 cells/ml in milk from uninfected/uninflamed mammary quarters.

The probability that a test is negative, given that the animal does not have the disease (see also sensitivity).

A ring-like muscle that maintains constriction of a bodily passage or orifice and opens upon relaxation.

To grow or to develop quickly (syn to germinate).

The main stem of an herbaceous plant.

Standard deviation (SD) is a measure of the dispersion of a set of data from its mean. If the data points are further from the mean, there is higher deviation within the data set. The SD shares the same unit as the mean. The SD is calculated as the square root of variance by determining the variation between each data point relative to the mean. The symbol for standard deviation is σ (the Greek letter sigma). Approximately, in a normal distribution,
38% of all observations are within ± 0.5 SD units of the mean;
68% of all observations are within ± 1 SD units of the mean;
95% of all observations are within ± 2 SD units of the mean;
99% of all observations are within ± 3 SDunits of the mean.

Carbohydrate found chiefly in seeds, fruits, tubers, roots, an stem pith of plants notably in corn, potatoes, wheat and rice. Warm season grasses (C4 plants) store starch in chloroplasts in leaf tissue. C4 grasses such as Bermuda Paspalum or Rhodes grasses grown under heat stress may contain considerable starch in leafy tissue. Nutritionally, it is referred to as non-structural carbohydrate as opposed to the carbohydrate found in the neutral detergent fiber of the plant.

The main upward growing axis of a plant, usually above the ground and in direction opposite of the roots.

A calf born dead or that dies within 48 hours of birth.

Fodder; mature-cured stalks from which seeds have been removed, such as stalks of corn or stalk of sorghum without heads.

The plant residue remaining after separation of the seeds in threshing. It includes chaff.

(see Fibrous carbohydrate).

Highly complex phenolic compounds in plants that may play a role of defense again microorganisms and possible predators (the herbivores). Tannin binds and reduces the availability of proteins and carbohydrates to ruminal microbes.

Property of feed detected by some papillae of the tongue and the roof of the mouth resulting in a positive or negative response to further ingestion of the feed.

A two-lobed gland located in the throat and secreting the hormone thyroxin, which regulates the iodine metabolism in the body.

Method of AI breeding in which the timing of artificial insemination (AI) is based on a hormonal protocol that synchronizes the timing of ovulation. This is in contrast to timing insemination based on direct or indirect detection of estrous behavior. Hormonal protocols for Timed AI were developed in 1995 and have been widely adopted by dairy producers for reproductive management.

Mixture of the forages, concentrates, minerals and vitamin supplements of a ration. The total mixed ration has the advantage of offering a balanced ration at each meal rather than on a 24 h basis.

A fat composed of three fatty acids and glycerol.

Digestive enzyme secreted by the pancreas and responsible for the break down of peptide bonds of proteins. Some plants contain a trypsin inhibitor that prevent trypsin from functioning properly.

Ray in sunlight which enables vitamin D to be synthesized under the skin.

Fat containing fatty acids that can accept hydrogen atoms to saturate their structure (e.g., oleic, linoleic, linolenic and arachidonic acids).

The parts of plants that are involved in the growth as opposed to the parts of plants involved in reproduction.

Particles that carry cholesterol and fat throughout the bloodstream. These particles are released from the liver into the bloodstream. They are similar to chylomicrons which originate from the gut because they both carry cholesterol and triglycerides which are gradually released in the bloodstream to be absorbed by body cells along the way. In the process of losing triglycerides, the VLDLs grow smaller and turn into LDLs (Low Density Lipoprotein) which have lost all their triglycerides.

Complex organic substances occurring naturally in plants and animal tissue and essential in small amounts for the proper functioning of numerous metabolic processes.

Evaporating readily at normal temperature and pressure.

Products of fermentation of carbohydrates (and some amino acids) by the rumen microorganisms. Acetic acid, propionic acid and butyric acid are the primary volatile fatty acids which are absorbed through the rumen wall and used as an energy source by the cow.

The number of days between calving and first attempt to breed a cow. A typical voluntary waiting period is 45 days. However, it may varies from less than 40 to 80 days depending on farmer’s preference and reproductive protocol in place on the farm.