Introduction to Minerals and Trace Elements

[Mustang Sally Farm]

Minerals and Trace Elements

Goats have an ability to thrive in the harshest environments. Their high digestive ability enables them to deal with high cellulose/high fibre diets of a very coarse nature. Anatomically goats are similar to other ruminants but with respect to mineral and vitamin requirements until recently, very little research had been carried out. That which has occurred has been performed almost by accident using goats as an inexpensive substitute for the cow. There is very little substantial data and very few definitive text books, which is very odd when one considers that there are over 400 million goats worldwide and more goats than sheep in the EU. In fact in some places e.g. The Sudan there are four goats for every person.

Recent surveys show that there are many areas deficient in certain minerals. However, the goat is an intelligent animal and usually manages on free range to eat herbs, weeds and other deep rooted plant material which has relatively high mineral content. However, real free range is very rare in the some countries and for that matter this is true over a large proportion of the world.

If a goat of say 40-45kg (88-99 lbs) bodyweight gives 4.5kg (1 gallon or 1.2 US gals)of milk per day that is equal to a cow of 500kg (1100 lbs) giving 50kg (11+ gallons or over 13 US gallons!) No such animal exists. A goat is at least 50% more productive and efficient for its bodyweight than a cow.

This means that if a goat is giving its own bodyweight in milk every 10 days or less, it is therefore utilising vast quantities of vitamins and minerals. At its extreme, top goats in the UK have been known to yield consistently 9kg (nearly 20 lbs) of milk per day, which is equivalent to her own bodyweight every 5 days!

A goat also needs more minerals and vitamins for maintenance too: with its relatively large digestive system in relation to its body size, the work of digestion involves the use, and loss, of large quantities of minerals.

Before we take the minerals and trace elements individually, there is no absolute distinction between the two - it is merely a matter of degree. Elements that are used at high levels are referred to as minerals, whereas low levels are called trace elements.

Calcium (Ca) and Phosphorous (P)
They are usually considered and always found together, yet they may be considered to be opposite in effect e.g. excess Ca is 'equivalent' to deficiency in P. They are also both interactive with vitamin D as well as iron and copper. 99% is stored in the skeleton and 1% or less is used vitally in enzymatic processes, cell transport, blood clotting etc.

The skeleton is the store for both Ca and P and somewhat surprisingly, the goat can add and draw from this reserve in times of deficiency. There is normally a positive calcium balance during pregnancy when the skeleton is added to and a negative balance after kidding where up to 30% of the skeleton may be utilised.

A goat requires 1.3g of Ca and 1.0g P for each 1kg of milk produced: it requires 7.lg Ca and 4.9g P daily for maintenance. If we consider both these figures it is obvious that a Ca:P ratio of 1.4:1 is ideal, suiting both the above.

Calcium deficiency manifests itself by rickets, milk fever (especially after kidding). Lack of Vitamin D will also help promote this, since it is required for retention of Ca in the bones. Phosphorous deficiency is more likely, less severe and harder to diagnose. Basically it causes 'poor thrift,' lower milk yields and general lethargy. Ca and P work on the thyroid gland together with Iodine to govern the metabolic rate - i.e. yield appetite, 'rate-of-living'. Very crudely, Ca acts as a brake and P an accelerator. Unlike cows, goats excrete a large proportion of Ca and P and therefore have a relatively large requirement.

Magnesium (Mg)
70% is found in the bones and teeth, the rest in the blood. Again up to a third can be mobilised at times of need. Some of the functions of Ca depend upon Mg too. A daily requirement of 1.2g per day is necessary. The first symptom is the lowering of the milk yield, possibly followed by magnesium tetany and hypomagnesaemia. This is most common when animals are put out on to lush grass in spring when the Mg content in the grass is at its lowest and requirement greatest. It is relatively rare in goats.

Zinc (Zn)
This is found in skin, hair and enzymes. Exact requirements are not known but between 10-60 p.p.m. is considered satisfactory. We do know that 6-7 p.p.m. does cause deficiency with stunted kids that do not thrive. Little Zn is available and must be supplied from the diet since it is not stored in the body as a reservoir. Deficiency symptoms are well documented although the extent and frequency are largely unknown. As an example, in Greece a survey of 150 goats showed 2% as having severe Zn deficiency.

Zinc has a profound effect on males - much more than females - since it is involved in sperm production and the development of the sex organs. Deficiency symptoms include high bacteria in the mouth with excess saliva, stiffness of the joints and a low male sex drive. In vegetable diets Zn combines with phytic acid to form insoluble salts and becomes unavailable. Dry diets are more likely to cause parakeratosis and wetting of the feed hydrolyses the phytate salts and liberates the Zn. - so wetting of the feed for males is recommended.

Zn deficiency is best spotted by the condition of the coat - there is reduced hair growth, a staring coat and also lameness. Zinc is not very toxic, one would need around 1000 p.p.m. to cause problems. However vast overfeeding or grazing in close proximity to smelting works has given rise to reports of excess, which interferes with iron and copper uptake, in turn giving anaemia.

Zn in milk is proportional to feed intake and since goats milk is usually too low in zinc to be ideal for human requirements, supplementing with Zn is a real benefit, especially when the milk is required for feeding to babies.

Manganese (Mn)
Occurs mainly in the liver and is another essential mineral, When fed at 5 p.p.m. in the feed, deficiency symptoms were noted. These included lethargy whereby goats would lay down a lot, walk poorly and deformities in the forelegs were also noticed. A change in the sex ratio in favour of male twins was reported and a lowering of the reproductive efficiency in the males and a lower conception rate in the females with delayed oestrus observed. A daily requirement of 60-90 p.p.m. in the feed is generally suggested as being ideal.

Iodine (I)
Low levels are needed daily - this is vitally important since goats can excrete 94% of their daily uptake via the milk, whereas cows lose only 2%. More Iodine in the diet gives directly more in the milk. It is also temperature dependent with six times more Iodine appearing in the milk at 30ºC than at 5ºC.

Iodine concentrates in the thyroid gland in the throat and is used in the production of thyroxine - thyroxine sets the pace for the goat's metabolism. Only 0.15mg per day is required but this is essential. The percentage of Iodine available is proportional to its concentration in the soil and not what is growing on it, i.e. the same Iodine percentage occurs in grass as in deep rooted weeds.

It is worth noting that Iodine should be fed with care as excess will easily put a goat off its feed. The main deficiency symptom is goitre whereby the thyroid swells in an attempt to work more efficiently with what little Iodine is available. A harsh coat is also common and perhaps the birth of live males, but dead female kids. The female has a larger thyroid gland and a bigger need for thyroxine and therefore a greater need for Iodine.

Copper (Cu)
Goats can get deficiency even at normal supplies if sulphur and cadmium are present - emissions etc. from factories are the main culprits. Again very small quantities are required and these must be consistently fed to aid digestion and utilise the iron by forming ceruloplasmin etc.

Again deficiencies are very noticeable in the coat with 'spectacles' forming around the eyes, especially noticeable with dark haired goats. More serious Cu deficiencies can be seen with the appearance of 'Swayback' where the back actually does sway and the goat has difficulty walking. In the UK the most well-known Swayback area is in Derbyshire and there are also 'Teart' areas where goats suffer Copper deficiency caused by the presence of excess Molybdenum in the soil which prevents the copper being absorbed. Cadmium also has the same 'blocking' effect as Molybdenum and this has occured when goatkeepers have put contaminated waste sludge on to their pastures to act as a fertiliser.

Selenium
This element is very toxic in anything other than really minute quantities, but is nonetheless essential. 0.2mg per day is officially recommended. Recent research has shown a link between Vitamin E and Selenium in which they act as co-partners in cell metabolism. Deficient areas exist e.g. here in the UK, the area around Lewes in Sussex is known to be deficient, as is most of New Zealand. The symptoms include white muscle disease and stillbirths.

Basic feedstuffs are often deficient in Se and many have selenium rich compounds added to compensate. Strangely, weeds and deep-rooted plants have a greater concentration of minerals than grass, yet for Se it is the same for all growth. Therefore the best guarantee for adequate Se is to 'Selenise' the soil via a special Se rich top-dressing.

Iron (Fe)
Most people know that Fe is a component of blood - haemoglobin contains 75% of the total in the body. Additionally, some is found in the enzyme systems and iron is fundamental to all living tissue. Deficiencies can occur, especially in kids due to low body reserves and exacerbated by the low iron content of goats milk during suckling (a big difference here with cows and sheep milk).

For adults a daily intake of 75mg is considered acceptable for lactating goats. Deficiency is relatively rare in farm animals with anaemia being the standard symptom. The diagnosis is not straightforward however since it is usually associated with other mineral imbalance problems. Iron toxicity is very rare because of huge doses needed to cause problems. The Fe in grass and oil meals (100-300mg per kg), in Dicalcium phosphates or limestone (500mg per kg) and cereal grains (30-60mg per kg) should provide enough. Any extra poses no problems and the Fe content of the milk is NOT dependent upon the diet (very different from Iodine).

Cobalt (Co)
There is a lot of data on this particular element and it is directly involved in the formation of Vit B12. Sheep have a greater need of Cobalt than cows and goats have 4 times the need of sheep! Deficiency gives off-flavours in the milk, loss of appetite, weakness, emaciation, anaemia, low productivity etc., and the latter symptoms are often categorised under the generic term 'pine'. 0.5 mg is required daily and it is most important that it is given on a daily basis.

For the relationship between Co and Vitamin B12, see the appropriate Vitamin paragraph below.

Sodium (Na)
1.5g per day is required, which is equivalent to about 3.5g of salt (Sodium Chloride). Large excesses are detrimental to Vit A uptake and excess in the diet is excreted in the goat's urine. There are large differences between goats as to preference to salt and a pure salt lick is the best (and cheapest) option. Salt blocks combined with vitamins are not ideal because the vitamin content will degrade fast in this aggressive environment.

It has been reported by McKenzie that all feral goats in the UK live near the sea because salt is so important to their existence. This is clearly nonsense since wild goats also exist in the centre of Asia 3000 miles from the sea!

Potassium (K)
It is now recognised that for goats relatively large quantities of K are needed. It is normally available in feedstuffs containing a high proportion of roughage and should not usually pose a problem. Deficiencies include emaciation, retarded growth, low feed intake with poor milk yields. It is not a toxic element and it is always a wise precaution to incorporate it in feed supplements.

Vitamins

Vitamin A
Now recognised as very important to all livestock including goats and its primary function is fortifying the outer defences of the skin and mucous membranes against disease. Vit A aids disease resistance and is required for good vision, lactation and reproduction. It is not yellow in colour but the carotenoid pigments found in carrots, maize etc. are bright yellow and contain the precursor to Vitamin A known as Carotene.

Carotene is converted in the intestinal wall and this depends upon the thyroid gland. Since the thyroid is very large in the goat, this animal is a very efficient converter of Vit. A - in fact all carotene is converted: this is why goats milk is pure white whereas the milk from cows (relatively inefficient converters) is still yellow with uncoverted carotene present.

Deficiency symptoms are rare and include night blindness, poor reproductive performance and metritis. Vitamin A is destroyed by sunlight and therefore old hay is very low in this vitamin. In winter make sure that kale and other feedstuffs high in Vit. A are fed.

For the new-born kid the colostrum is very important since they have very small reserves of Vit. A. It is worth noting that the Vitamin A content of goats milk is directly proportional to the amount of beta-carotene occuring in the feed.

Vitamin D
Closely connected with Calcium and Phosphorous, Vit. D is required for the deposition and remobilisation of the above into the skeleton. It is the antirachitic (prevents rickets) vitamin and its main source is from sunlight and is formed on the skin. Absorption is through the skin or by simply licking off.

Deficiency symptoms are uncommon but goats that are kept indoors in winter etc. are most likely to suffer and therefore need supplementary feeding. Deficiency of Vit. D is a major cause of rickets, bow legs and osteomalacia and whilst it cannot make up for any absolute deficiency in Ca and P, Vit. D will compensate to some extent to help overcome any imbalance between the two. As in cows, there is a high output of Ca & P into the milk and Vit. D is needed to maintain mobility of these minerals. It has been suggested in France that extra Vit. D is given in the last weeks of pregnancy to prevent hypocalcaemia (milk fever) and this does seem to be very sensible.

Vitamin E
As discussed Vit E is tied up with Selenium as a co-partner, but there are still some doubts as to its exact function. It is known to be concerned with the cell nucleus, the development of the foetus and the performance of the males. It is an antioxidant, facilitating absorption, storage and protection of Vit. A.

Vit. E is found in oil meals and bran - however, if goats can be persuaded to eat cod liver oil, recent evidence shows that deficiency symptoms are CREATED by forming gut conditions favourable to the destruction of both Vit. E and Selenium.

The method of storage of feedstuffs is very important as the concentration of Vit. E is dependent upon it: basic feedstuffs can easily be made to be very deficient simply by bad storage conditions. Goats transfer Vit. E into the milk more readily than cows and should therefore receive daily adequate supplies of this vitamin to ensure milk quality. Apart from white muscle disease and muscular dystrophy, lack of Vit. E also causes sterility in males.

Note that kids have no reserves of fat soluble vitamins (A,D & E) and sudden death of kids less than 2 weeks old is often due to lack of Vit. E in particular. This is normally overcome by feeding colostrum but the Vit. E content is also affected by the nutrition of the dam during pregnancy.

With kids there is degeneration of muscle including the heart, whereas in older animals it will manifest itself as stiffness of the limbs.

The B Vitamins
Goats along with other ruminants are blessed with bacteria that live in the rumen and synthesise the B vitamins. Therefore it has been suggested that supplementation is not necessary, but there are several reasons for Vit. B inclusion:

1. inhibition of synthesis of certain B Vitamins by substances in feedstuffs occurs, especially those with high starch levels.

2. parasites in the gut totally remove certain B vitamins.

3. some B vitamins cannot be synthesised in sufficient quantities to meet demand - especially with heavy milkers and the shortfall must be provided via the feed.

Vitamin B1 (Thiamin)
Conventional feedstuffs contain fairly constant amounts of B1 and the higher the amount fed the lower the amount synthesised. However diets with high carbohydrate content increase the requirement of B1 which is one reason why straight grain diets should not be fed since they act as Vit. B1 antagonists.

There is a relationship between Vit B1 deficiency and disease resistance and deficiency causes damage to the central nervous system (polioencephalomacia and cerebrocorticalnecrosis - PEM and CCN). This is exhibited by collapse, twitching etc. and the only cure is Vit B1 injection. 50-60mg per day is the recommended daily intake. Vit. B1 is also used as a preventative for acetonaemia. Nicotinamide. Also a member of the B group vitamins. Recent evidence again shows limited synthesis and the majority of the vitamin is derived from the goat's feed intake. Supplementation improves milk production and butterfat levels.

There is good evidence that Nicotinamide present in cereals is 'bound' i.e. not available and therefore must be added by supplementation in the diet.

Pantothenic acid
This is another of the B group vitamins. In high cellulose diets e.g. where hay comprises a large percentage, the biosynthesis of Pantothenic acid is impaired.

It is found in fresh vegetables and, in milk, bound to the proteins. It serves an important function in the formation of enzymes and certain antibodies, and since recent evidence has shown that deficiency can occur, it is always best to incorporate it in the feed via supplementation on a daily basis.

Vitamin B12 (Cyanocobalamin)
Directly associated with Cobalt, Vit. B12 has a Cobalt nucleus in a highly complex molecule. Large excesses of Cobalt in the gut will result in analogues of Vit B12 being formed these are identical to the natural vitamin except for a slight molecular variation. These analogues surprisingly have zero vitamin activity, despite being 99+% identical to the original and will cause Vit B12 deficiency symptoms (outlined under Cobalt).

Obviously, administering even more Cobalt is NOT the answer as this creates further problems and the best solution is to ensure a low daily dose of Cobalt is provided and in the case of B12 deficiency, an injection of this vitamin, whilst the gut flora returns to a normal healthy state.

Much more research is needed in this vital science - very little data is available to goatkeepers with respect to Vitamin C, Vitamin K, Biotin, Folic Acid as well as other trace elements such as Fluorine, Chromium etc. - and what about amino acids, enzymes, fatty acids etc.? Only time and continued research will enable us to understand more fully the requirements of the goat and thus be able to cater adequately for her needs.

[Mustang Sally Farm]

Whichever weaning method you use, kids must be consuming, and have ready access to, high-quality solid food if they are to be weaned young. As a guide, the ration should contain a minimum of 11 MJ (megajoules) of metabolic energy and about 180 g of crude protein (18 per cent) per kilogram of dry matter, plus a mineral and vitamin mix (see Table 2). The ration may include some high-quality roughages, such as chaff, to assist rumen development. It is important for clean water to be available at all times.

 

Table 2. Recommended level of minerals and vitamins
 for goat feeds per kilogram of dry matter
 (from Morand-Fehr 1981)



Sodium

2 g



Magnesium

2 g



Sulfur

1.5 g



Copper(a)

10 mg



Cobalt

0.1 mg



Zinc

75 mg



Manganese

50 mg



Iodine

0.2 mg



Selenium

0.1 mg



Vitamin A

5000 IU



Vitamin D

1400 IU



Vitamin E

100 IU

[Mustang Sally Farm]

website on the topic of Copper Bolusing

 http://noodlevilleadventures.blogspot.com/2012/01/noodleville-how-to-copper-bolusing.html

[Mustang Sally Farm]

Understanding & Significance of Forage Analysis Results
(unless otherwise noted, the following information pertains to ruminants, cattle in particular).

Moisture – the percent water in a sample.

Dry matter – equals (100% - Moisture) and represents everything in the sample other than water including protein, fiber, fat, minerals, etc.. Animals consume feeds to meet their dry matter needs, because it is the dry matter that contains all of the nutrients. Therefore, animals will have to consume more of a wetter feed to receive the same amount of dry matter as they would from a drier feed. For example, if an animal consumes 20 lbs. of hay at 90% dry matter, it consumes 18 lbs. of dry matter (20 x .90). If haylage at 40% dry matter was to be substituted for the hay, it would have to consume 45 lbs. of haylage (18/.40) to receive the same amount of dry matter.

Thus, it is very important to know the dry matter content of a feed to establish feeding rates and insure that livestock receive the proper amount of feed to meet their daily needs.

As Sampled Basis – nutrient results for the sample in its natural state including the water. Also known as as fed or as received.

Dry Matter Basis – nutrient results for the sample with the water removed. There is considerable variation in the moisture content of forages. Removing the water eliminates the dilution effect of the water thereby enabling direct comparisons of nutrient contents across different forages. For example, suppose that you wanted to compare the protein content of a hay testing 90% dry matter to a haylage testing 40% dry matter. On an as sampled basis the hay tested 14% crude protein (CP) and the haylage 8% CP. The hay appears to have the higher CP level. However, removing the dilution effect of the water reveals that the hay is 15.5% CP (14/.90) and the haylage is 20% CP (8/.40) on a dry matter basis. Thus, removing the dilution effect of the water revealed that per pound of dry matter, the haylage is higher in protein. Animals eating the haylage will consume more protein per pound of dry matter than they will from the hay.

Livestock nutrient requirements may be expressed on either an as sampled or dry matter basis. It is important to use analytical results expressed on the same basis as the nutrient requirements. In general, most livestock requirements are expressed on a dry matter basis, therefore, the forage results on a dry matter basis should be used to balance the ration. Again, the key point is to make sure that the requirements and results are expressed on the same basis.

Protein and Protein Fractions
Crude Protein (CP) – the total protein in the sample including true protein and non-protein nitrogen. Proteins are organic compounds composed of amino acids. They are a major component of vital organs, tissue, muscle, hair, skin, milk and enzymes. Protein is required on a daily basis for maintenance, lactation, growth and reproduction. Proteins can be further fractionated for ruminants according to their rate of breakdown in the rumen.

Urea and Ammonia – reported as crude protein equivalent (CPE). Urea and ammonia are not proteins. However, they contain nitrogen that can be used by the microbial population in the rumen to synthesize protein. They are classified as non-protein nitrogen (NPN). Thus, although they are not true proteins, they supply nitrogen which can be used to form microbial protein and therefore have a certain value that is equivalent to protein for ruminants. The reported result is the CPE contribution from each of these compounds. The results are not the percent urea or ammonia in the feed. The actual percentage in the feed can be calculated by dividing the urea CPE by 2.81 or the ammonia CPE by 5.15. The urea and ammonia appear in the soluble protein fraction of the protein.

Soluble Protein (SP) – proteins and non-protein nitrogen that are rapidly broken down in the rumen. They are used to synthesize microbial protein in the rumen.

Degradable Protein (RDP) – consists of the soluble protein and proteins of intermediate ruminal degradability. They are used to synthesize microbial protein in the rumen.

Undegradable Protein (RUP) – proteins that have a slow rate of degradability and escape digestion in the rumen. UIP is also known as escape or bypass protein and reaches the lower gastrointestinal (GI) tract essentially intact. The undegradable protein is broken down in the GI tract as it would be in nonruminants.

Acid Detergent Insoluble Crude Protein (ADICP) – also known as heat damaged or unavailable protein. Typically caused by heating during fermentation or drying, a portion of the protein reacts with carbohydrates to form an indigestible complex rendering it unavailable for digestion. ADICP escapes ruminal breakdown and represents the portion of the undegradable protein that is unavailable to the animal.

Neutral Detergent Insoluble Crude Protein (NDICP) – it has been suggested that the NDICP represents the portion of the undegradable protein that is available to the animal.

Carbohydrates
Neutral Detergent Fiber (NDF) – a measure of hemicellulose, cellulose and lignin representing the fibrous bulk of the forage. These three components are classified as cell wall or structural carbohydrates. They give the plant rigidity enabling it to support itself as it grows, much like the skeleton in animals. Hemicellulose and cellulose can be broken down by microbes in the rumen to provide energy to the animal. NDF is negatively correlated with intake.

Acid Detergent Fiber (ADF) – a measure of cellulose and lignin. Cellulose varies in digestibility and is negatively influenced by the lignin content. As lignin content increases, digestibility of the cellulose decreases. ADF is negatively correlated with overall digestibility.

Lignin – undigestible plant component. Lignin has a negative impact on cellulose digestibility. As lignin content increases, digestibility of cellulose decreases thereby lowering the amount of energy potentially available to the animal.

Crude Fiber (CF) – historical method of fiber analysis used to divide carbohydrates into digestible and indigestible fractions. Crude fiber accounts for most of the cellulose and only a portion of the lignin. It is not the most accurate method for quantifying fiber, particularly for forages. However, given that grains are low in lignin, it is a reasonable estimate of fiber in grains and is still used today as the legal measurement of fiber in grains and finished feeds.

Pectin – a cell wall polysaccharide that functions as "cellular glue". Also known as "soluble fiber", it possesses the rapid and extensive degradation characteristics of nonstructural carbohydrates, yet without the propensity to lower rumen pH or cause lactic acidosis.

Starch – a polysaccharide found primarily in the grain or seed and/or root portions of plants. Starch is a good source of energy.

Water Soluble Carbohydrates (WSC) – carbohydrates solubilized and extracted in water. Includes monosaccharies, disaccharides and some polysaccharides (mainly fructan). Fructan is a major storage carbohydrate in grasses.

Ethanol Soluble Carbohydrates (ESC) – carbohydrates solubilized and extracted in 80% ethanol. Includes primarily monosaccharides and disaccharides.

Non Fiber Carbohydrates (NFC) – non-cell wall carbohydrates consisting of starch, sugar, pectin and fermentation acids that serve as energy sources for the animal. In ruminants, NFC are broken down by the microbial population in the rumen and used as an energy source. NFC is calculated as 100% - (CP% + (NDF% - NDICP%) + Fat% +Ash%).

Fat
Fat – typically determined by ether extraction. In addition to fat, ether extraction may solubilize plant pigments, esters and aldehydes. This is why the measurement is called crude fat. Fat is an energy dense nutrient and contains 2.25X to 2.8X the energy found in carbohydrates. Fat is added to rations to boost energy levels when intake may be limiting.

Energy
Energy is the nutrient required in the greatest amount. Energy is used in all biological processes and is essential for life. For livestock, energy requirements are determined for maintenance, growth or gain, lactation, reproduction and activity level. Failure to supply adequate energy will result in poor performance. Energy values are not measured, rather they are predicted using equations and relationships with other nutrients. Dairy One uses a multiple component summative approach for its ruminant energy prediction system. Energy contributions from protein, fiber, nonstructural carbohydrates and fat form the foundation of the system. Discounts are applied to reflect energy available for productive purposes.

Ruminants
Total Digestible Nutrients (TDN) – denotes the sum of the digestible protein, digestible NSC, digestible NDF and 2.25X the digestible fat.

Gross Energy – the total energy value of a feed before accounting for losses due normal digestive, metabolic and productive functions.

Digestible Energy (DE) – equals gross feed energy minus energy lost in the feces.

Metabolizable Energy (ME) – equals gross feed energy minus energy lost in the feces, urine and gases.

Net Energy for Lactation (NEl) – an estimate of the energy value of a feed used for maintenance plus milk production during lactation and for maintenance plus the last two months of gestation for dry, pregnant cows.

Net Energy for Maintenance (NEm) – an estimate of the energy value of a feed used to keep an animal in energy equilibrium, i.e., neither gaining or losing weight.

Net Energy for Gain (NEg) – an estimate of the energy value of a feed used for body weight gain above that required for maintenance.

SS NEl – corn silage NEl value adjusted for starch digestibility using the Schwab-Shaver adjustment factors.

SS Proc. NEl – corn silage NEl value adjusted for starch digestibility as described above plus the effect of whole plant processing.

NRC 2001 Energy Table – energy values determined using the system described in the 2001 NRC Dairy Cattle publication. The NEl table reflects the decline in energy value of a feed associated with increasing levels of milk production, dry matter intake and rate of passage.

Horses
Total Digestible Nutrients (TDN) – denotes the sum of the digestible protein, digestible nitrogen-free extract (NFE), digestible crude fiber and 2.25X the digestible fat. TDN is estimated from digestible energy (DE).

Digestible Energy (DE) – equals gross feed energy minus fecal energy. It is predicted from ADF and CP for forages and ADF for grains.

Minerals
Ash – a measure of the total mineral content. Samples are weighed and incinerated at 600oC for two hours. This burns off all of the organic material (protein, fiber, fat, etc.) leaving behind the minerals. The ash residue weight is then divided into the original weight to determine the percent ash.

Calcium (Ca) – bone and teeth formation, blood clotting, muscle contractions, milk component, transmission of nerve impulses, cardiac regulation, activation and stabilization of enzymes.

Phosphorus (P) – bone and teeth formation, key component of energy metabolism, milk component, body fluid buffer systems.

Magnesium (Mg) – enzyme activator, found in skeletal tissue and bone, neuromuscular transmissions.

Potassium (K) – osmotic pressure regulation and water balance, electrolyte balance, acid-base balance, enzyme activator, muscle contraction, nerve impulse conductor.

Sodium (Na) – Acid-base balance, muscle contraction, nerve transmission, maintenance of body fluid balance, osmotic pressure regulator, cellular uptake of glucose, amino acid transport.

Iron (Fe) – hemoglobin and oxygen transport, enzyme systems.

Zinc (Zn) – enzyme activator, wound healing, skin health, some impact on udder health (reduced somatic cell counts (SCC)).

Copper (Cu) – required for hemoglobin synthesis, coenzyme functions.

Manganese (Mn) – growth, bone formation, enzyme activator, fertility.

Molybdenum (Mo) – part of enzyme xanthine oxidase, antagonistic and interactive effects with copper and sulfur.

Sulfur (S) – needed for microbial protein synthesis, especially when non-protein nitrogen (NPN) is fed.

Chloride (Cl-) – acid-base balance, osmotic pressure regulation, component of gastric secretions.

Cobalt (Co) – required for vitamin B12 synthesis.

Selenium (Se) – component of glutathione peroxidase enzyme, antioxidant properties, prevention of white muscle disease and retained placenta.

Other
In Vitro True Digestibility (IVTD) – an anaerobic fermentation performed in the laboratory to simulate digestion as it occurs in the rumen. Rumen fluid is collected from ruminally cannulated high producing dairy cows consuming a typical total mixed ration (TMR). Forage samples are incubated in rumen fluid and buffer for a specified time period at 39oC (body temperature). During this time, the microbial population in the rumen fluid digests the sample as would occur in the rumen. Upon completion, the samples are extracted in neutral detergent solution to leave behind the undigested fibrous residue. The result is a measure of digestibility that can be used to estimate energy.

Neutral Detergent Fiber Digestibility (NDFD) – The proportion of NDF potentially available as determined by an in vitro incubation. NDFD is expressed as a percentage of the NDF. The NDFD can be used to rank forages on potential fiber digestibility and in energy calculations.

Relative Feed Value (RFV) – an index for ranking forages based on digestibility and intake potential. RFV is calculated from ADF and NDF. A RFV of 100 is considered the average score and represents an alfalfa hay containing 41% ADF and 53% NDF on a dry matter basis. The higher the RFV, the better the quality.

Due to the inherent variability of measuring ADF and NDF, absolute RFV values should not be used for making direct comparisons or pricing of forages. Rather a range of RFV values should be used to classify a forage. For example, if a RFV of 150 is the target value, any forage testing between 145 to 155 should be considered to have an equivalent value. A good rule of thumb is to accept anything within at least +/- 5 points of the target value.

Relative Forage Quality (RFQ) – an index for ranking forages based on a more comprehensive analysis than RFV. RFQ is calculated from CP, ADF, NDF, fat, ash and NDF digestibility measured at 48 hours. It should be more reflective of the feeding value of the forage. RFQ is based on the same scoring system as RFV with an average score of 100. The higher the RFQ, the better the quality.

Milk lbs./ton – a projection of potential milk yield per ton of forage dry matter based on digestibility and energy content of the forage.

Nitrates (N03) – can be come a problem when fed in high amounts. Nitrate accumulator plants include sorghum, sorghum sudangrass, sudangrass, weeds and small grain forages. Drought, frost, fertilization and manure application practices are factors that can lead to high nitrate levels. Drought stricken corn silage is particularly susceptible. Nitrates accumulate in the bottom portion of the stalk and it is often recommended that suspect corn silage be chopped higher than usual. Nitrate levels may be reduced by up to 50% by ensiling.

When nitrate is converted to nitrite, it impedes the uptake of oxygen by the blood resulting in death due to lack of oxygen. Blood becomes brownish in color and exterior membranes may become bluish in color.

pH – a measure of the degree of acidity. Good corn silage typically has a pH of 3.5 - 4.5 and haycrop silages 3.8 - 5.3.

Volatile Fatty Acids (VFA) – primarily lactic, acetic, propionic and butyric acids produced as a result of microbial fermentation in silage or the rumen.