Feed Additives Flashcards
Various nonnutritive substances added to a ration to:
-stimulate growth or other types of performance
-improvement of feed utilization of feed efficiency
-improving the health of the animal
Factors other than bio-efficacy considered relative to the use of an additive:
-cost
-toxicity
-tissue residues
Do feed additives produces their response in young, rapidly growing animals or mature animals?
young, rapidly growing animals
What are the two exceptions of additives that benefit mature animals?
-buffers
-thyroprotein compounds
Some feed additives have demonstrated ___________ responses and others demonstrated fairly ____________ responses
-situation-specific
-universal
Most common nonnutritive additives in common use:
-antibacterial agents
-hormones and their derivatives
-others (buffers, activated charcoal, antioxidants, bentonite, bloat-control compounds, methane inhibitors, enzymes, coccidiostats, B-agonists)
The two types of antibacterial agents:
-antibiotics
-sulfa drugs
Feed additive classifications
-medications
-antioxidant
-antifungal agents
-enzymes
-direct-fed microbials
-essential oils
-fermentation products
-herbs
-pellet binders
-surfactants
-pigments
-flavors
-stool conditioners
-buffers
Sub-therapeutic antibiotics action
antimicrobial
Sub-therapeutic antibiotics decreases:
-sub-clinical infections
-growth depressing microbial metabolites
-gut maintenance
-competition for nutrients
Organic acids action
antimicrobial (Gr-)
Plant extracts action
-varied physiological functions
-antimicrobial
-altered mucin production
-decreased intestinal “turnover”
Probiotics action
-specific pathogen exclusion
-immunological modulation
-improved nutrient use
-antimicrobial action (decrease pH and bacteriocins)
What are antimicrobial agents and anthelmintics defined as by the FDA?
drugs
What does the FDA regulate with antimicrobial agents?
-usage levels
-allowable combinations
-periods of withdraw prior to slaughter
Antibiotics
a compound synthesized by a living organism which inhibits the growth of another organism
What are antibiotics effective in?
-improving performance
-their ability to suppress or inhibit growth of certain microorganisms
Absorption of antibiotics
some are readily absorbed into the vascular system, others are hardly absorbed at all
General performance enhancement levels fed:
low levels of 5-50 g/ton
Disease prevention levels fed:
50-200 g/ton feed
Therapeutic levels fed:
200-500 g/ton
Therapeutic additives are used for:
-control of respiratory diseases
-diarrhea
-short-term treatment of the entire group of animals
Effects of antibiotic feeding
-reduced morbidity
-reduced incidence of secondary infections
-reduced incidence of dehydration and pneumonia
What happens to animals responding to antibiotic feeding?
-consume more feed than controls
-gain weight faster, so less food is needed per unit gain
Uses for antibiotics in cattle:
-best benefit to young stressed calves arriving to feedlot and cattle that has been mismanaged
-reduced the incidence of liver abscesses on high grain rations for feedlot cattle
Uses for antibiotics in sheep:
-used for finishing lambs
-used for feedlot lambs
Uses for antibiotics in dairy cows:
-does not increase milk production
-feeding high levels of antibiotics is prohibited by law because residue could carry into the milk
Antibiotics effects on the nutrition of animals must be __________
secondary, because they are drugs not nutrients
The metabolic affect of antibiotics:
the drug affects various enzyme systems such as oxidative phosphorylation reactions
The nutrient-sparing effect of antibiotics:
via altered microbial composition of the GI tract where the antibiotic may:
-stimulate microorganisms that favor nutrient synthesis of a critical nutrient
-suppression of organisms which compete with host for dietary needs
-improved nutrient absorption = thinner, healthier intestinal walls
Disease control of antibiotics:
benefits from suppression or control of subclinical or non-specific diseases
Societal concerns for antibiotics:
-have antibiotics become less effective from antibiotic resistant strains?
-does feeding antibiotics pose a public health threat?
Does feeding antibiotics pose a public health threat?
-antibiotic resistant strains of non-pathogenic bacteria with transferable resistant (R) factors emerge in the intestines of the animal being fed antibiotics
-R factors may be transferred to virulent bacteria in the animals
-Virulent, antibiotic-resistant bacteria a passed on to man
What is the difference in resistant bacteria in rural (works with animals) vs. city living?
nothing, failed to detect any differences
MGA
melengestrol acetate, a synthetic progestogen
What does MGA do when fed to feedlot heifers?
-suppresses estrus
-appears to promote growth (which may be due to water retention)
Synovex
S = 200 mg progesterone + 20 mg of estradiol benzoate
H = 200 mg testosterone + 20 mg of estradiol propionate
-sex specific
What does synovex do?
-increases of 10-15% in ADG
-savings in feed
Ralgro
-brand of zeranol
-acts like an estrogen
Zeranol
the active compound is resorcyclic acid lactone, a product isolated from a type of corn mold
-Ralgro is a brand of this
What does Ralgro do?
-acts like estrogen
-response is best with high quality rations (rations with an adequate supply of protein and energy)
DES (diethylstilbestrol)
a synthetic estrogen that was used for ~18 years in cattle industry before its removal in 1972
What industry was DES used in?
cattle
Bovine SomatoTrophin (BST)
injectable growth hormone
What does Bovine SomatoTrophin do?
increases milk production in dairy cattle
What has received widespread interest in animal production?
thyroid-active hormones
Thyroid-Active hormones
-use of thyroxine and thyroproteins
-mostly commonly used for lactating cows and ewes
-feed consumtion will generally increase
Activated Carbon-=
-fed at a rate of 5% of the diet to reduce the recycling of such pesticides as dieldrin and DDT in dairy cows
What happens when activated carbon is fed?
much of the exrected compounds may be absorbed and passed out of the body
How are pesticides recycled?
via the bile
Bentonite
sodium bentonite is a relatively inert mortmorillonite clay
What is bentonite often used as ?
a pellet binder
Benefits come from the addition of ______% bentonite to diets containing __________
0.5%; aflatoxin
Bloat control compounds
shown considerable promise for control of pasture bloat provided a relatively regular intake can be obtained
Buffers
needed when shifting ruminants from a high roughage diet to a high concentrate diet
What does buffers need to be followed by?
a rapid introduction of a highly fermentable CHO source in the diet
Indicators of needing buffers:
-high concentrate diets = less chewing and cud regurgitation = less salivary secretions = less bicarbonate being returned to the rumen
-high contrate diets = high acid production from VFA’s and the inability of microorganims to shift rapidly with a build up of lactic acid results in further rumen pH decline
-high concentrate diets offer little buffering capacity themselves
-faulty mineral ratios in mineral supplements would benefit from a buffer sometimes
3 instances buffers are useful:
-use of ammonium in pre-partum cows may reduce the incidence of milk fever
-low milkfat problems - buffers help return to normal milk fat %
-sudden ration shifts to high concentrate diets
Enzymes
-must be matched to the substrate
-may need protection from certain GI environmental factors
Methane inhibitors
used because 10% of the total energy intake of ruminants is lost as methane
B-agonists
re-partitioning agent fed for a period of time before slaughter that directs nutrients more toward protein deposition and away from fat deposition
Moat common B-agonist
ractopamine
Mold products
-antibiotics
-mycotoxins
Mycotoxins
toxic metabolites of filamentous fungi (molds)
secreted to protect mold’s food
Myco =
fungus
Toxin =
poison or toxicant of fungal origin
Mycotoxicoses
diseases produced by mycotoxins
Cytotoxicity
disrupting cell membranes, protein DNA synthesis
How many molds produce toxins?
100
How many molds are mainly toxic for animals?
13
What products are mycotoxins more common in?
cereals and oilseeds (not as much in animal products)
Moulds
aerobic multi-cellular organisms
What does mould growth require less of than bacterial growth?
less available water
Do all moulds produce mycotoxins?
no
________ are secondary metabolites of mould growth
mycotoxins
General effects of mycotoxins are dependent on what?
-toxin dependent
-dose dependent
General effects of mycotoxins
-feed refusal
-digestive problems: diarrhea, vomit
-nervous system (tremors, weakness, staggering)
-reproduction (from conception to abortion
-immune suppression
-organ damage
-teratogenic (embryonic malfunctions)
-carcinogenic
-death
Important mycotoxins in US:
-Aflatoxins
-Zearalenone
-Trichothecenes (T-2 toxin, vomitoxin)
-Fumonsin
-ochratoxin
Aflatoxins are associated with field crops where in the US?
-north carolina
-arizona
-arkansas
Ergotamine are associated with field crops where in the US?
colorado
Tremorgens are associated with field crops where in the US?
-northern california
-louisiana
DON (Vomitoxin) are associated with field crops where in the US?
-south dakota
-Michigan
Ochratoxin are associated with field crops where in the US?
south carolina
Zearalenone are associated with field crops where in the US?
Wisconsin
Factors contributing to aflatoxin formation:
-storage conditions (humidity)
-grain humidity (>13%)
-water stress (drought or wet harvest)
-insect damage
-high temperatures (90 F during critical time in development)
-plant variety
-planting density
-soil fertility
-late planting and harvest date
Black sclerotia (ergots) is caused by what?
claviceps purpurea infection in barley
Aflatoxins aspergillus:
> 185 Sps
Aflatoxins attack what?
the vascular system (hemorrhages)
What might help aflatoxin affects?
vitamin K
Aflatoxin
-teratogenic
-one of the most potent carcinogens
What occurs in most feeds?
mycotoxins and moulds
Aflatoxins B1
the most hepatotoxic, carcinogenic and prevalent
Aflatoxins M1
aflatoxin metabolite in milk
Acute primary mycotoxicoses
-high toxins
-hepatitis, nephritis, necrosis of epithelium, death
Chronis primary mycotoxicoses
-lower toxins over a longer period of time
-detriments growth performance
Secondary mycotoxic diseases
-even lower toxins
-immunosuppression
What happens to liver with increased aflatoxins?
the liver pales
Ammoniation (2%)
one of the most effective preventatives of mold growth in stored grains
Organic acids
-prevents mold growth in stored grains
-propionic, acetic, sorbic, benzoic
Salts of organic acids
-prevents mold growth in stored grains
-calcium propionate, potassium sorbate
-less effective than acids
Reducing aflatoxin content
-mechanical screening (separating grains)
-chemical inactivation: ammonia, methylamine, sodium hydroxide, formaldehyde, HCl, NH3, H2O2
-Propionic acid
-heating (not effective)
-blending (prohibited by FDA)
Inorganic binders (mineral clays)
-alters response to mycotoxins
-bentonite
-zeolites
-hydrated sodium calcium aluminosilicates
Organic binders
-alters response to mycotoxins
-cell wall carbohydrates from yeasts
Methods of altering responses to mycotoxins:
-inorganic binders
-organic binders
-increase plane of nutrition (protein, energy, and vitamin contents)
-dehydrated alfalfa meal
