Term
| One of the most significant factors, which determine the nutritive value of a feed |
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Definition
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Term
| the portion of the feed that can be taken up by the animal |
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Definition
| portion which is soluble or is rendered soluble by hydrolysis or some other chemical or physical change |
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Term
| the most reliable method of measuring a feed's digestibility |
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Definition
The total collection (conventional digestion trial)
however, this is tedious and time consuming |
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Term
| how to calculate nutrient digestibility |
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Definition
| nutrient digestibility (%) = ((nutrient intake - nutrient in feces) / (nutrient intake)) * 100 |
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Term
| The most common arrangement for collecting the excreta of animals for digestibility experiments |
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Definition
through the use of metabolic crates
distorts results due to stressing the animal |
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Term
| how to calculate the digestibility of a nutrient in the test feed stuff being fed in form of mixed feed |
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Definition
Digestibility of nutrient in test feed (%) = ((A)- (B) (C) X 100)/(D)
A = Digestibility of nutrient in total diet
B = Digestibility of nutrient in basal diet (usually already determined when fed alone
C = proportion of total nutrient in diet supplied by basal diet
D = proportion of total nutrient in diet supplied by test feed. |
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Term
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Definition
| reference substance that is a natural constituent of the feed |
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Term
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Definition
| reference substance added to the feed |
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Term
| criteria of a good marker in feed analysis |
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Definition
-strictly non absorbable
-must not affect or be affected by the gastrointestinal tract or its microbial population
-must be physically similar to or intimately associated with feed material
-its method of estimation in digesta samples must be specific and sensitive and not interfere with other analyses |
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Term
| how to calculate digestion coeffecient of dry matter |
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Definition
| Digestion coefficient of dry matter = 100 - (100 * (% Indicator in feed DM / % Indicator in fecal DM)) |
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Term
| how to calculate digestion coeffecient of a nutrient |
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Definition
| Digestion coefficient of a nutrient = 100 - (100 * ((% Indicator in feed * % Nutrient in feces) / (% Indicator in feces * % Nutrient in feed))) |
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Term
| some factors that affect digestibility |
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Definition
-feed intake
-particle size
-chemical composition
-feed processing
-climate
-age
-exercise |
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Term
| how feed intake can affect digestibility |
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Definition
| The plane of nutrition is one of the primary factors that affect digestibility of any feed. Experiments have showed that livestock usually, digest a larger percentage of the nutrients in their feed when fed restrictedly than when they receive full feed (Okin & Mathison, 1991; Faichney, 1993; Poppi et al. 1981a). Most data indicate some depression in apparent digestibility as level of intake is increased. This may be due to a more rapid movement of feed through the tract, thus allowing less time for digestion and absorption. |
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Term
| how particle size can affect digestibility |
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Definition
| Much data exist indicating that forage digestibility is depressed by grinding to a very fine particle size (Galloway et al., 1993; Alwash & Thomas, 1974; Firkins et al., 1986). Fine grinding also apparently increases rate of passage that consequently reduces the digestibility. |
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Term
| how chemical composition can affect digestibility |
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Definition
| One of the most significant factor, which affect digestibility is the chemical composition of the feeds (Poppi et al., 1981b; Luginbuhl et al., 1994; Sarwar et al., 1985). Digestibility of one feed is believed to differ from that of a similar feed because each may contain different contents of certain chemical entities, particularly since some of these diminish the opportunity for the digestive enzymes to come in contact with their respective substrates. On the other hand, digestibility of complete feeds can be enhanced by the additions of relatively small quantities of specific nutrients such as protein or soluble carbohydrates. |
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Term
| how feed processing can affect digestibility |
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Definition
| Processing of feedstuffs is conducted in an attempt to enhance digestibility (Faichney, 1986; Sarwar et al., 1992). Changes in physical form can influence digestibility of the dry matter, energy, protein or any of the organic substances in feed products. Such processes as drying, grinding, pelleting and wafering all act to generally affect digestibility. Chemical, biological treatments and chopping improve the digestibility of fibrous feeds (Sarwar et al., 1994). |
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Term
| how climate can affect digestibility |
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Definition
| The digestibility was higher at higher temperature than in a cold environment which may be due to higher mean retention time of the feedstuff in the digestive tract (Faichney, 1986). In some studies (Kennedy et al., 1976; Kennedy & Milligen, 1978; Kennedy, 1985), sheep exposed to cold (0ºC) had a lower digestibility than controls in warmer temperatures (22ºC). Increased reticulo-rumen motility in the sheep exposed to cold temperature (Kennedy, 1985) may be responsible for the decreased mean retention time. Increasing passage rate in such circumstances could serve as a strategy for increasing dry matter consumption to meet demands for higher energy imposed by cold climate (Merchen, 1988). Neural and endocrine regulation of ruminal contractions in animals exposed to cold have also been reported, but the precise mechanism is still to be determined (Kennedy et al., 1980). |
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Term
| how age can affect digestibility |
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Definition
| It is generally felt that animal individuality affects digestibility more than age. However, older animals appear to better digest some nutrients (e.g., fiber, minerals) than do the young of their species. The evidence available indicated that, in general, age itself makes little or no difference in the ability of animals to digest nutrients. In the case of ruminant species, the young cannot digest much roughage until their digestive tracts, especially their rumens, are developed. Also the ability of old animals to digest feed is often impaired by poor teeth, which makes adequate chewing of their feed difficult. Declining health might further adversely affect digestibility at an advanced age. However, the digestibility of feed by younger animals may often be influenced more by the presence of parasites. |
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Term
| how exercise can affect digestibility |
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Definition
| Although some workers have found that exercise hastens the process of digestion, it is generally considered to be a factor of minor importance. Other factors such as frequency of feeding, amount of water ingested and animal species may also affect digestibility but the data are contradictory and work remains to be done on these relationships. |
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