Withdrawal of antibiotic growth promoters from broiler diets: performance indexes and economic impact.

This study aimed to estimate the productive and economic impacts caused by the withdrawal of antibiotic growth promoters (AGP) from broilers diet. Indexed publications that compared diets with or without AGP (AGP+/AGP-) for broilers (from initial to final phase) were collected and the results of feed intake, weight gain, and feed conversion were compiled in a database. A meta-analysis was performed following sequential analyses: graphical approach (to observe biological data coherence), correlation (to identify related factors), and variance-covariance (to compare groups). The annual number of broiler slaughtered in Brazil, target weight gain and feed conversion for each phase, the variation in feed conversion, feed cost, and AGP costs were used to build a model to estimate the effects of the AGP withdrawal on feeding costs. The database comprised 174 scientific articles containing 183 experiments, totaling 121,643 broilers, most of which were Ross (52% of the studies). The most frequent AGP sources/forms in the database were Avilamycin (41% of the AGP+ treatments), Flavomycin (19%), Virginiamycin (16%), and Bacitracin (14%). Higher feed intake, weight gain, and lower feed conversion were attributed (P < 0.05) to AGP+ diets during Initial phase (1 to 21 D). In Final phase (22 to 42 D) no differences were observed in performance variables. Treatments AGP+ presented higher weight gain and better feed conversion in the Total period (1 to 42 D). The results of feed conversion were improved (P < 0.05) with Avilamycin and Flavomycin; Virginiamycin improved weight gain and feed conversion. In the Total period, the economic impact was $0.03 per animal and a total of $183,560,232 per year. It was concluded that broilers fed AGP+ diets have higher weight gain and better feed conversion than those fed AGP- diets, and withdrawing AGP increases production costs.

Growth-promoting technologies decrease the carbon footprint, ammonia emissions, and costs of California beef production systems.

Increased animal performance is suggested as one of the most effective mitigation strategies to decrease greenhouse gas (GHG) and ammonia (NH(3)) emissions from livestock production per unit of product produced. Little information exists, however, on the effects of increased animal productivity on the net decrease in emission from beef production systems. A partial life cycle assessment (LCA) was conducted using the Integrated Farm System Model (IFSM) to estimate GHG and NH(3) emissions from representative beef production systems in California that use various management technologies to enhance animal performance. The IFSM is a farm process model that simulates crop growth, feed production, animal performance, and manure production and handling through time to predict the performance, economics, and environmental impacts of production systems. The simulated beef production systems compared were 1) Angus-natural, with no use of growth-enhancing technologies, 2) Angus-implant, with ionophore and growth-promoting implant (e.g., estrogen/trenbolone acetate-based) application, 3) Angus-ß2-adrenergic agonists (BAA; e.g., zilpaterol), with ionophore, growth-promoting implant, and BAA application, 4) Holstein-implant, with growth implant and ionophore application, and 5) Holstein-BAA, with ionophore, growth implant, and BAA use. During the feedlot phase, use of BAA decreased NH(3) emission by 4 to 9 g/kg HCW, resulting in a 7% decrease in NH(3) loss from the full production system. Combined use of ionophore, growth implant, and BAA treatments decreased NH(3) emission from the full production system by 14 g/kg HCW, or 13%. The C footprint of beef was decreased by 2.2 kg carbon dioxide equivalent (CO(2)e)/kg HCW using all the growth-promoting technologies, and the Holstein beef footprint was decreased by 0.5 kg CO(2)e/kg HCW using BAA. Over the full production systems, these decreases were relatively small at 9% and 5% for Angus and Holstein beef, respectively. The growth-promoting technologies we evaluated are a cost-effective way to mitigate GHG and NH(3) emissions, but naturally managed cattle can bring a similar net return to Angus cattle treated with growth-promoting technologies when sold at an 8% greater premium price.

Mecasermin: new drug. Insufficient improvement in statural growth.

(1) Human insulin-like growth factor type 1 (IGF-1) is the main effector of growth hormone action. Primary IGF-1 deficiency is a rare disease, mainly resulting in very short stature; (2) Mecasermin is a recombinant IGF-1 marketed for this indication as a twice daily subcutaneous injection; (3) Clinical evaluation is mainly based on a non-comparative follow-up study of 76 children with an average age of 7 years, some of whom were treated for 8 years. The mean height at treatment initiation was 6.7 standard deviations below normal. Eight years later, it was 5.2 standard deviations below normal, i.e. their growth failure remained very severe; (4) The main short-term adverse effects of mecasermin are hypoglycaemia, headache and intracranial hypertension. Nearly one in 5 children developed tonsillar hypertrophy, resulting in otitis and hypoacusis; (5) Animal studies showed hypertrophy of other organs (kidneys, spleen and heart) as well as carcinogenic effects. The risk in humans is unknown; (6) The mecasermin packaging is not well-adapted (a multidose vial designed to be punctured several times), and is a potential source of contamination and errors. Prefilled pens or syringes would be easier to use; (7) In practice, the limited clinical benefits of mecasermin do not justify exposure to its potential risks.

Growth-promotant implants: managing the tools.

Great contemplation, conversation, and controversy have surrounded the use of growth-promotant implants since their inception in the 1950s. Since the very beginning, the purpose of growth promotants has been to enhance production efficiency, reduce the cost of production, and improve profitability. Changes in our understanding of the physiologic mechanisms involved in growth promotion have not altered this fundamental purpose. With enhanced knowledge of the impact of various compounds and doses on different classes of animals, and with the introduction of numerous products providing those compounds and doses, planning implant programs has become difficult. However, the net return from a well-designed implant program may mean the difference between profit and loss on a given set of cattle.

A study of the factors that influence consumer attitudes toward beef products using the conjoint market analysis tool.

This study utilizes an analysis technique commonly used in marketing, the conjoint analysis method, to examine the relative utilities of a set of beef steak characteristics considered by a national sample of 1,432 US consumers, as well as additional localized samples representing undergraduate students at a business college and in an animal science department. The analyses indicate that among all respondents, region of origin is by far the most important characteristic; this is followed by animal breed, traceability, animal feed, and beef quality. Alternatively, the cost of cut, farm ownership, the use (or nonuse) of growth promoters, and whether the product is guaranteed tender were the least important factors. Results for animal science undergraduates are similar to the aggregate results, except that these students emphasized beef quality at the expense of traceability and the nonuse of growth promoters. Business students also emphasized region of origin but then emphasized traceability and cost. The ideal steak for the national sample is from a locally produced, choice Angus fed a mixture of grain and grass that is traceable to the farm of origin. If the product was not produced locally, respondents indicated that their preferred production states are, in order from most to least preferred, Iowa, Texas, Nebraska, and Kansas.

Animal growth promoters: to ban or not to ban? A risk assessment approach.

The use of antibiotics for animal growth promotion has been controversial because of the potential transfer of antibiotic resistance from animals to humans. Such transfer could have severe public health implications in that treatment failures could result. We have followed a risk assessment approach to evaluate policy options for the streptogramin-class of antibiotics: virginiamycin, an animal growth promoter, and quinupristin/dalfopristin, a antibiotic used in humans. Under the assumption that resistance transfer is possible, models project a wide range of outcomes depending mainly on the basic reproductive number (R(0)) that determines the potential for person-to-person transmission. Counter-intuitively, the benefits of a ban on virginiamycin were highest for intermediate values of R(0), and lower for extremely high or low values of R(0).

The role of growth factor administration and T-cell recovery after peripheral blood progenitor cell transplantation in the treatment of solid tumors: results from a randomized comparison of G-CSF and GM-CSF.

BACKGROUND: Peripheral blood progenitor cell (PBPC) transplantation (PBPCT) combined with post-PBPCT administration of myelopoietic growth factors is a valid therapeutic intervention to rapidly restore hematopoiesis after the delivery of intensive, myeloablative cancer chemotherapy. On the other hand, the best growth factor regimen to potentiate PBPC-mediated immunohematopoietic recovery has yet to be determined. STUDY DESIGN AND METHODS: In a randomized evaluation, the effects produced by post-PBPCT G-CSF and GM-CSF on myeloid/lymphoid recovery and transplant outcome in women with chemosensitive cancer were compared. Thirty-seven ovarian cancer patients and 34 breast cancer patients ranging in age from 24 to 60 years were treated with carboplatin, etoposide, and melphalan (CEM) high-dose chemotherapy and then randomly assigned to receive G-CSF (5 microg/kg subcutaneously) or GM-CSF (5 microg/kg subcutaneously) until Day 13 after PBPCT. Patients were compared in regard to hematopoietic recovery, posttransplant clinical management, and immune recovery. Finally, clinical outcome was estimated as time to progression and overall survival. RESULTS: Hematopoietic recovery and posttransplant clinical management were comparable in both the G-CSF and GM-CSF series. Conversely, significantly higher T-cell counts were observed in G-CSF-treated patients during the early and late posttransplant follow-up. Patients who received G-CSF showed a significantly longer median time to progression. A parallel analysis revealed that patients in whom a higher CD3+ count was recovered had a significantly longer overall survival and time to progression. CONCLUSION: The enhancement of post-PBPCT T-cell recovery observed in G-CSF-treated patients encourages the use of G-CSF to ameliorate immune recovery, which seems to play a role in post-PBPCT control of disease in cancer patients. GM-CSF might be administered to prolong immunosuppression after autologous PBPCT for autoimmune diseases or allogeneic PBPCT.

[Use of growth factors in therapy of chronic wounds. Experimental, clinical and financial aspects]. / Zum Einsatz von Wachstumsfaktoren in der Therapie chronischer Wunden. Experimentelle, klinische und finanzielle Aspekte.

Clinical trials on exogenous application of polypeptide growth factors in chronic wounds have not fulfilled the high expectations derived from results of experimental studies. There is no convincing evidence that growth factors may substitute for good wound care and efficient surgical approaches to wound closure. The ultimate goal of treatment of chronic ulcerations remains reconstitution of a durable skin envelope without unstable scarring. Therefore, optimization of current methods of wound therapy, including reconstructive vascular and plastic surgery and adequate metabolic and wound control, should be employed before any adjuvant growth factor therapy is attempted. As long as efficient and inexpensive therapy of chronic wounds by growth factors has not been demonstrated, empincal growth factor treatment should be rejected on scientific and economic grounds. Current use appears to be reasonable only under a regime of controlled clinical studies comparing growth factor treatment with conventional wound therapy and operative measures according to the rules of "good clinical practice".

A literature assessment of the use of miscellaneous topical agents, growth factors, and skin equivalents for the treatment of pressure ulcers.

BACKGROUND: Agents reviewed for this manuscript were both rare and popular topical treatments for pressure ulcers. OBJECTIVE: To review topical treatments for pressure ulcers and evaluate them based on available literature of controlled, blinded, and randomized trials. METHODS: A MEDLARS database (1966-1993) search and a thorough review of reference article lists of key articles produced over 100 manuscripts. Studies were considered for review if they were conducted on humans with chronic stage II to IV pressure ulcers, in a properly controlled and randomized fashion. RESULTS: The use of zinc acetate and aluminum hydroxide ointment, phenytoin, recombinant platelet-derived growth factor-BB (rPDGF-BB), and basic fibroblast growth factor (bFGF) have been evaluated in a controlled and blinded fashion. Many of the newer agents, cytokine growth factor (eg, rPDGF-BB and bFGF) and skin equivalents, are currently being scrutinized in clinical trials. CONCLUSION: A paucity of data exist that adequately address the efficacy of any topical agent for the treatment of pressure ulcers.