Flashcards in Final Deck (55):
we eliminate all of the potential factors that can influence heat production, then we can obtain a minimum energy expenditure associated with maintenance of life, and it is called
When we think about the “maintenance need” for protein or N, a couple of very obvious important terms would pop into your head such as________________ and other biologically active N compounds (ex Histamine & carnitine).
enzymes and peptide hormones
Most minerals can easily form____________ thus their absorption rate is generally very low. Exceptions are Na, Cl, & K.
salts or other insoluble compounds
The sense of ____ is important for pigs where as _____ is important for poultry.
4) Obviously the major difference between fat and water soluble vitamins is solubility but another major difference would be
fat sol stored in fat, water vit constantly replenished.
5) It seems that “gastrin” is the focal point of regulating gastric secretion and _____________are primarily factors involved in controlling gastrin secretion, thus the activity of the stomach.
histamine and secretin
Unlike pigs) Chickens do not have a “stomach” per se, and they use their
crop for food storage, proventriculous for enzyme secretion, and gizzard for grinding respectively.
7) What are gizzard teeth?
Well they are uniquely associated with the fowl and consisted of a protein-polysaccharide complex known as koilin which form rods that can protrude through the lining of the luminal surface.
8) Obviously, ____________ are very important in energy metabolism, and it seems that plasma glucose is the major factor controlling their secretion.
glucagon and insulin
9) Well, as we mentioned, horses seem to have a lot of digestive/nutritional related problems such as
colic and stomach rupture(disorders).
1) Under _________, C-skeletons cannot be oxidized to CO2. Consequently, the end products of rumen fermentation are mostly VFAs.
10) Having ________ is important for young ruminants so that milk can flow directly into the omasum/abomasums which results in better utilization of milk.
11) As we mentioned, animals may be “marginally” deficient or excess in certain nutrients but we may not realize that all simply because
they show no clear signs or symptoms.
12) It seems that “mineral metabolism” is a bit different from metabolism of most other nutrients such as protein, simply because
minerals aren't broken down
13) In practice, “fattening or finishing” is an integral part of “growing” animals for the commercial meat production. But, as we mentioned, it is not part of “growth” because
growth involves protein, minerals and water, and fat is energy storage.
14) It would be important for us to have some ideas on “interactions” of minerals for two important reasons:
avoid undesirable reactions & secondary deficiencies.
15) We did talk about estimating nutrient digestibility just briefly. And, we use the term, “apparent” rather than saying “digestibility or true digestibility” simply because
it does not consider metabolic fecal nutrient.
16) As we mentioned, laying hens and lactating sows mobilize a lot of “Ca and P from bones” which can lead to leg problems! The best way to alleviate such problems seems to be
Supplement Ca & P during gestation.
17) For most species, “esophagus” is simply a passage way for food/feed but it does have some implications for “horses” because
their smooth muscle is one way peristaltic contractions; cannot vomit or burp.
18) In the small intestine, “2 sets of glands” are primarily responsible for digestive secretions. The 1st one is _______ or duodenal glands which can secrete viscous mucous. The second is_______ or intestinal glands which secrete mucous and enzymes.
crypts of lieberkuhn
19) Briefly we talked about changes in pH as ingesta/digesta move thru gastrointestinal tract and the pH changes seem to be important for
reducing microbial growth/load and keeping at optimum pH for enzymes to work properly
_______which account for 40-50% of total dry weight of most plans, cannot be utilized efficiently by us & most other nonruminant species simply because:
don't have enzyme to break B-1.4 linkage; only microbes do
21) When we are dealing with ruminant species we often hear the term ketosis. Ok, what is exactly ketosis and how does it happen
Buildup of ketone bodies observed in blood/tissues from lack of propionate or oxalate.
22) Obviously, there are some advantages in having “rumen” but everything is not perfect. Some disadvantages are
lots of time/energy/work spent chewing, lots of energy used in fermentation, inefficient protein synthesis, rely on microbes, and wasted energy via methane and CO2.
We had some discussion on “indispensible and dispensable” nutrients in class. Perhaps we should not say a “nonessential amino acid” but perhaps we can use the term “nonessential” if we include the term “dietary”. I.e. “dietary nonessential amino acid”.
We had some discussion on indis and dis. Now we can say a ‘nonessential amino acid’ without any problem, but we should not say a ‘nonessential mineral’ because metabolically all minerals are essential.
When we consider protein synthesis; we have to remember that the process is not exact. That is many mistakes can take place during the translation process thus increasing energy expenditure greatly as well as protein or amino acid needs.
Females seem to have no special needs for energy or nutrients before breeding but if they are not consuming sufficient energy or nutrients during last 1/3 gestation, we can definitely expect adverse effects on their reproductive performance.
A balance test may not be a good way to estimate mineral requirements simply because the balance can be affected by many other factors…other than dietary concentration or intake of mineral in question that is.
To estimate protein needs we have to consider urinary N, fecal N, and hair/nail growth
A main advantage of using radioactive indicator in studying mineral metabolism? Well we are not really increasing the content of particular element in feed or physiological concentration of the element thus we are not disturbing the animal’s normal metabolism
Throughout history, people had to deal with many serious diseases/disorders, and we now know some are caused by deficiency of some vitamins. Ex. Beriberi thru Thiamin and pellagra thru Niacin.
- Although a borderline deficiency of vitamin is common, unaware bc no clear signs. Especially true for fat-soluble vitamins.
One reason that chickens have high heart rate has to do with # of erythrocytes, which seems to be less than half of many mammals!
Pigs have a poorly developed “olfactory mechanism” and having unheated mouth, thus no release of volatile compounds may have something to do with poor smell. (Chickens actually do have poor developed olfactory mechanism).
in terms of ‘prehension’ chickens don’t have good mechanism, horses use lips, cattle use tongue to consume feed.
- It seems that pig’s saliva contains ptyalin or amylase but not in chickens, horses, ruminants, cats or dogs.
As we mentioned, regardless of species, majority of nutrients are digested and absorbed at upper portion of small intestine, especially at the ileum(answer jejunum), even though some nutrients can be absorbed at the lower portion, ex B12 at the colon.
The “duodenum” is primary a mixing site for all nutrients in digesta. That is, bile, pancreatic secretions, ect. Would be mixed with digesta in the duodenum, but not as much digestion or absorption would take place in this part of small intestine.
- In chickens, two long ‘ceca’ are primary fermentation sites; cannot utilize fiber efficiently perhaps bc the entrance to each cecum is somehow restricted thus only small particles and fluids can enter the ceca.
It seems that chicken’s lymphatic system is poorly developed, which has some implications bc unlike other species, they’d have to absorb long-chain FA directly into portal circulation system…somehow.
“Somatostatin” is a hormone originally identified as an inhibitor of growth hormone, & it may be involved in day-to-day regulation of nutrition thru it effects on the action of insulin and glucagon.
Pepsin is mostly responsible for intestinal digestion of protein, and it (actually there seem to be 4 diff types in pigs & humans) has 2 pH optima, 2, and 3.5.
We often hear the terms ‘ruminal acidosis and bloat” Well simply, acidosis caused by too much lactic acid; bloat is excessive accumulation of these gases.
Although most carbs would be fermented by rumen microbes, small amt of carbs can escape. “Escaped” soluble carbs cannot be digested/absorbed efficiently by the host animal’s digestive enzymes.
Two most likely limitations for ‘microbial protein synthesis’ seem to be availability of energy and ammonia but under practical conditions, ammonia is the limiting factor because carbs are readily fermented in the rumen to produce a lot of VFA!
It seems that most VFA are absorbed from forestomach wall and absorption rate might be greater if ruminal pH is reduced and chain length increased.
Although ruminant species can have a functional rumen by 8 wks, we can say that they are essentially ‘nonruminant’ during first couple months after birth.
It’s amazing that each milliliter of rumen content contains 10-50 billion bacteria, 1 million protozoa and variable number of yeasts and fungi.
Maintenance energy needs estimated by measuring fasting heat production(define). Also, we mentioned fasting metabolic rate is not adequate to satisfy maintenance energy need under practical conditions. Why?
Heat production: the conversion of energy/nutrients to work is not 100% efficient, energy that’s not converted to work is released as heat. – Fasting metabolic rate is not adequate to satisfy ME needs bc it does not consider all factors such as energy needed to eat, activity, & other needs. Animals are active.
Brush-border enzymes such as lactase, sucrose, peptidase. What’s unique about intestinal enzymes when comparing to pancreatic enzymes? What is meant by villi and microvilli and are they factors that influence the status of them?
These enzymes are shed; pancreatic enzymes are secreted. Microvilli are tiny projections from intestinal wall contains brush boarder, increases the SA better absorption of nutrients. pH, water, and microbes influence & high turnover rate.
We determined energy/protein digestibility of corn in pigs and chickens of 3 cities. What kind of conclusion or inferences can we make by looking at this data?
Most energy is released at end of digestion at rectum/cloaca; this is where breakdown of nutrients and VFA’s occurs and protein is stored in duodenum.
Horses have advantages of ruminant and nonruminants. Do they really though? Elaborate
Their hindgut ferments and uses cellulose and VFAs like ruminants’ large intestine, similar small intestine to non ruminants. Designed to utilize forages but are commonly fed grain and concentrates that can’t be used efficiently either. Can reduce problems by small, frequent feeding throughout day. Can synthesis vitamins, proteins, AA like ruminants & can ferment nutrients directly like nonruminants.
When discussing rumen fermentation of dietary protein, concluded that VFA’s most impt. Why?
Crude protein is broken down to AA ketoacids +ammonia used by bacteria to make microbial protein. Ammonia also used in cycle that involves VFAs.