17, 18 Flashcards
1
Q
Definition of Hormonal Growth Promotants (HGPs)
A
- HGPS are a group of veterinary drugs that mimic the hormones that influence animal growth.
- Improves the rate of:
- gain, and/or feed conversion
- They may be natural or synthetic.
- Hormones are banned by legislation in the EU!
- The Food and Drug Administration (USA) has approved the use of growth promoting hormones such as estradiol, progesterone, testosterone, trenbolone acetate and zeranol. More than 20 countries use these hormones regularly and have reduced greenhouse gas emissions, energy use, water use and reactive nitrogen loss of beef production in comparison to beef raised without growth promoting hormones.
2
Q
Growth hormone (STH; anabolic)
A
▪ In mammals it stimulates the protein synthesis ,
▪ In poultry it stimulates the fat synthesis,
3
Q
Steroids
A
- Androgens (testosterone; anabolic)
- Stimulate protein synthesis of the muscle,
- Inhibit the catabolic effect of glucocorticoids,
- Estrogens
- In ruminants it increases the daily gain and improve the nitrogen accretion,
4
Q
Repartitioning agents
A
- β-adrenergic agonists (they increase amino acid requirements)
- Affect metabolism via adrenergic receptors on specific tissues (adrenaline-like effect),
- Pigs fed beta agonists are: leaner and have more muscle mass, less body fat,
- β-adrenergic agonists are banned by legislation in the EU!!
- Food and Drug Administration approved ractopamine hydrochloride and zilpaterol hydrochloride in animal feeds.
5
Q
Classification of feed additives and growth promoters
A
1. Physiological regulators or metabolic modifiers
- Hormones: steroids, growth hormones
- Repartitioning agents: B-adrenergic agonists
2. Nutritional/zootechnical feed additives, nutraceuticals
- Antibiotics: Virginiamycin, Monenzin, lasalicid etc.
- Clay minerals, rumen buffering agents: Zeolite, Bentonite: MgO, NaHCO3
- Acidifiers: Lactic acid, propionic acid, formic acid etc.
- Botanical and herbal extracts: oregano, garlic oil
- Yeast: Saccharomyces cerevisiae
- Probiotics and prebiotics: Lactobacillus, MOS, FOS
- Fat burners: carnitin, chromium picolinate etc.
- Antioxidants: organic Se, Vitamin E
- Growth promoting minerals: CuSO4, ZnO
- Other substrates: w3-fatty acids, CLA, lecitins.
6
Q
- Improve
- Growth
- Feed conversion
- Reproductive performance
- Cure or prevent specific diseases at high concentration. Two points of concern:
- Antibiotic resistance: antibiotics used in human medicines hould not be used as growth promoter (Swann report; HMSO1969),
- Withdrawal time!
- Antibiotics are banned as feed additives/growth promoters in the EU, except ionophores as anticoccidials.
- In 2017, the FDA banned the use of antibiotics to make animals grow quicker, a practice known as growth promotion.
A
7
Q
Ionophores
A
- Coccidiosis prevention: chicken, turkey, rabbit,
- it appears that ionophores do not dontribute to the development of antibiotic resistance to important human drugs. Ionophores are not used in human medicine,
8
Q
Ionophore toxicity
A
- seen in cattle, sheep, pigs, dogs, cats, rabbits and poultry
- horses are particulatly susceptible!
- clinical symptoms of lasalocid toxicity in dogs and cats:
- polyneuropathy
- hyporefelxia
- dysphagia, tetraparasis
- respiratory weakness and eventually muscle atrophy
9
Q
Clay minerals
A
- Counteracting mycotoxins and mold-inhibiting agents (Aflatoxin, deoxynivalenol – DON),
- Zeolite, bentonite bind aflatoxin, but do not bind all mycotoxins. Zeolite is able to absorb NH3.
- Feeds must be low in mikotoxins or free from mikotoxins. Adding clay minerals is not a solution!
10
Q
Rumen buffering agents
A
- NaHCO3 and MgO
- they reduce the speed of NH3 production
- stable pH in the rumen
- Acute/chronic rumen acidosis Intake of a high level of rapidly digestible carbohydrate, lactic acid ↑, pH ↓
11
Q
Yeast, Saccharomyces serevisiae
A
- Interactions with ruminal microbial biomass (bacteria, protozoa, fungi) (esstablishment, growth, activites) by;
- consumption of sugar: competition with lactate producing bacteria
- Oxygen scavenging
- decreased rumen lactic acid: stimulation of lactate consuing bacteria
- result:
- raises and stabilizes pH
- limits risk of acidosis
- ncrease fibre degradation
12
Q
Acidifiers
A
- Definition: acidic agents, that decrease the stomach pH level (in feed or drinking water)
- Organic acids:
- Formic acid
- Acetic acid
- Propionic acid
- Fumaric acid
- Citric acid
- Lactic acid
- Malic acid
- Bethaine-HCl
13
Q
Effects of Acidifiers
A
- Lower gastric pH (pigs!),
- Increase activity of proteolytic enzymes,
- Inhibit proliferation of pathogenic bacteria (E. coli; Salmonella)
- Improve:
- mineral solubility
- daily gain
- feed conversion (mainly during the nursery period in pigs)
- Energy source,
- Dose: 0,3-0,5%
- Pigs;
- rabbits (diet rich in alfalfa),
- struvit stones in dog, cat – NH4Cl, methionine,
14
Q
Enzymes
A
- Addition of specific enzymes, such as
- protease,
- Amylase (foal, pigs),
- Lipase
can augment and complement endogenously secreted enzymes.
- Addition of
- α-galactosidase,
- NSP splitting enzymes (Non Starch Polysaccharides), e.g.: Pentosane
- Phytase,
- Xylanase,
can specifically target anti-nutritive factors which impair digestion and therefore provoke digestive disturbances.
- „digest” (dog and cat food)
15
Q
Effect of enzymes
A
- Increase digestibility,
- Modification of gut physiology:
- transittime(intestinal),and
- secretion(endogenous),
- Change of gut microflora:
- substrates available to various bacteria
- oxygen tension in the gut
