Animal production level

Within the framework of the Residue Avoidance Program, producers have also had much success in implementing preventive measures to address the problem of drug residues at the animal production level. As a result of these efforts, animals such as bob veal calves, cull dairy cows, and market hogs, which were singled out by the FDA to be a major problem just a few years ago, are not of concern regarding drug residues any more. 

The relative proportions of NE required for maintenance and production, calculated as (NEjn + NEg)/NEjn, is sometimes referred to as animal production level (APL). In this example, the APL would be calculated as (23 +11.5)/23 = 1.5. 

Those of us that have done basic research have tended to look at enzyme activity, pathway activity, hormone and receptor concentrations and the like. That is fine, and we have learned from that, but in many oases we did not consider the underlying controls (transcription rates, enzyme synthesis rates) or did not fully relate the cellular information to the animal production level in any systematic mathematical formalism. The former is difficult to do, expensive, and in many ways not necessary to our purposes in animal agriculture. The latter is easy to do, inexpensive and in fact an absolute requirement for our purposes what are the true biological controls, at the level at which control is exerted, that drive animal production. A description of metabolic control theory and control coefficients is beyond the purpose of this article, but readers are at least encouraged to read some of Kacser, Carson and Cobelli and Comish-Bowden to understand this (Comish-Bowden, 2005). I will go into more detail with references on multiple regressions to study the relationship of basic metabolic control, transcriptomics and animal production below. 

There is some help in terms of setting some of the performance characteristics. The European Community implementing Council Directive 96/23/EC has considered the level of bias (trueness) and precision appropriate for analytical methods used to monitor the concentrations of certain substances and residues of the substances in animal products for concentrations ranging from 1 ig kg-1 to 1 mg kg l. Their recommendations for the trueness and precision of analytical methods are shown in Tables 4.2 and 4.3, respectively. However,... 

Advocates for the use of hormones in animal production claim that the levels of hormones found in several common foods greatly exceed the levels at... 

The advisability of using certain antibiotics, particularly penicillin and tetracycline, in animal feeds has been questioned because of their use in human medicine. Any use of an antibiotic that is prescribed for humans presents some risks to human health, whether the use is for humans, animals or for other purposes but. the uses also have benefits. Otherwise, they would not persist. Antibiotics are used in animal feeds to increase animal weight, increase efficiency of feed utilization, increase reproductive efficiency and decrease morbidity and mortality. These benefits to animals and animal producers are reflected in decreases in food costs to humans. There are also benefits to human health from use of antibiotics in food animals. By reducing the incidence of animal health problems, use of antibiotics in food animals reduce the transference of animal infections to humans. The contention that the effectiveness of penicillin and tetracycline for use in human medicine is rapidly diminishing as a result of the proliferation of resistant bacteria caused by subtherapeutic use of antibiotics in animal production is not supported by experimental data. Rather, the evidence suggests that a fairly stable level of resistance of the intestinal bacteria in humans has long since been established to penicillin and tetracycline as it has been in animals. 

Some supporters of the proposed FDA ban on the use of subtherapeutic levels of penicillin and tetracyclines in animal feeds hailed the results of the CDC study as a clear link between subtherapeutic antibiotic use in food animal production and antibiotic-resistant diseases in humans. Some opponents, on the... 

The really important point is not whether this particular CDC investigation did or did not demonstrate the link, but rather, are there problems and. if so. how important are the problems resulting from use of antibiotics at subtherapeutic levels in animal feeds In other words, would discontinuing the subtherapeutic use of tetracycline and penicillin have a significant effect on antibiotic resistance in consumers of animal products ... 

The production of PBBs in the United States ceased in 1979 (lARC 1986). In the past, PBBs were released to the environment during the manufacture of these compounds and disposal of commercial and consumer products containing these compounds (Hesse and Powers 1978 Neufeld et al. 1977). One of the significant sources of environmental contamination occurred as a result of the accidental mixup of FireMaster BP-6 with cattle food in a number of farms in the lower peninsula in Michigan (see Section 3.2 for additional details concerning this incident). By June 1975, 412 farms had been quarantined. Disposal of contaminated feed, animal carcasses (poultry, dairy cattle, swine), and animal products (dairy, meat, eggs) contributed to environmental contamination (Dunckel 1975 Kay 1977). No information was located on the current levels of contamination at these locations. 

In principle, all drug preparations administered to food-producing animals may lead to residues in the edible tissues, milk, or eggs. In addition to the drug dosage, the levels of those residues depend on the period between administration and slaughter or collection of the animal products, the so-called withdrawal period, which, on its turn, depends on the pharmacokinetic profile of the drug. 

The most serious objections to the presence of drug residues in food intended for human consumption arise as a consequence of human health considerations. With tire extensive use of drugs in animal production, residues of the parent drugs and/or metabolites have a high potential to be present in the edible animal products. The public health significance of such adulteration of the food supply is determined mainly by the level of the residues and the individual drugs they are originated from. 

The conditions under which the drug is used need to be estimated as do acceptable residues linked to the level of acceptable risk to the consumer. The acceptable level of risk, which is determined in theory at the risk management stage, has already been expressed in terms of residues by the ADI under hazard characterization. Moreover, the elements considered for hazard identification, hazard characterization, and exposure assessment make it possible, for a given form of utilization of a particular substance, to establish a profile of residues in animal tissues and to associate this with a profile of consumer exposure. Comparison of this consumer profile and ADI indicates whether the mode of utilization of the substance is acceptable or not. Analysis of the different results of residue content in animal products then provides an indication of level of residues in one or several animal tissues, making it possible to differentiate between veterinary drug applications that do or do not permit compliance with the ADI. 

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