Commercial Animal Production Research Articles

Non-Chemical Control of Nymphal Longhorned Tick, Haemaphysalis longicornis Neumann 1901 (Acari: Ixodidae), Using Diatomaceous Earth

The longhorned tick (LHT), Haemaphysalis longicornis Neumann (Acari: Ixodidae), is a serious invasive pest in North America where its geographical range is expanding with high densities associated with commercial animal production. There are only a few chemical pesticides available for LHT control, which can lead to the evolution of resistant strains. Diatomaceous earth (DE) was shown to be effective in killing some important tick species but was not examined for LHTs. When LHT nymphs were dipped for about 2–4 s into DE, transferred to Petri dishes (one tick/dish), and incubated at 30 °C and 70% relative humidity, the median survival time was 4.5 h. A locomotor activity assay showed that there was no difference in the overall distance traveled between the DE-treated and control ticks except during the first 2 h after exposure. In a field-simulated study in which a dose of 5.0 g DE/m2 was applied to pine needle litter infested with LHT, all the LHTs were dead at 24 h with no control mortality. Scanning electron micrographs showed the mineral adhering to all surfaces of the tick. The results indicated that DE is effective in killing nymphal LHTs and could be an alternative to the use of chemical acaricides with the advantage of managing pesticide resistance through the killing by a different mode of action and could be used for organically certified animal husbandry.

Cochlosoma anatis in Poultry and its Industry Impact.

Cochlosoma anatis is a flagellated protozoan parasite classified in the Trichomonadidae family and is the causative agent of cochlosomiasis, an enteric disease of turkeys, waterfowl, and other wild birds. Cochlosomiasis symptoms largely consist of watery diarrhea, lethargic birds, depressed weight gain, and widespread flock morbidity causing flock nonuniformity. The known distribution of C. anatis is centered around areas of turkey production farms in the southeast United States, e.g., North Carolina, Missouri and Arkansas, but has been reported in other states and some other countries. Diagnosis is confirmed through examination of enteric mucosal scrapings using light microscopy. Following the withdrawal of approval of effective antiprotozoal medications for use in commercial animal production, cochlosomiasis has become a greater concern for commercial turkey industry professionals. Transmission of C. anatis occurs via the fecal-oral route, but the organism is fragile outside the host, suggesting the implication of a vector in the introduction of disease to susceptible farms. Research regarding C. anatis pathogenicity, transmission, and environmental involvement has been limited, creating a gap in cochlosomiasis knowledge. Future research is needed to further explore ways to prevent and treat cochlosomiasis, with needs centered on disease pathogenesis, transmission patterns, and prophylaxis and treatment methods.

Risk factors for extended-spectrum beta-lactamase (ESBL)-producing E. coli carriage among children in a food animal-producing region of Ecuador: A repeated measures observational study.

The spread of antibiotic-resistant bacteria may be driven by human-animal-environment interactions, especially in regions with limited restrictions on antibiotic use, widespread food animal production, and free-roaming domestic animals. In this study, we aimed to identify risk factors related to commercial food animal production, small-scale or "backyard" food animal production, domestic animal ownership, and practices related to animal handling, waste disposal, and antibiotic use in Ecuadorian communities. We conducted a repeated measures study from 2018 to 2021 in 7 semirural parishes of Quito, Ecuador to identify determinants of third-generation cephalosporin-resistant E. coli (3GCR-EC) and extended-spectrum beta-lactamase E. coli (ESBL-EC) in children. We collected 1,699 fecal samples from 600 children and 1,871 domestic animal fecal samples from 376 of the same households at up to 5 time points per household over the 3-year study period. We used multivariable log-binomial regression models to estimate relative risks (RR) of 3GCR-EC and ESBL-EC carriage, adjusting for child sex and age, caregiver education, household wealth, and recent child antibiotic use. Risk factors for 3GCR-EC included living within 5 km of more than 5 commercial food animal operations (RR: 1.26; 95% confidence interval (CI): 1.10, 1.45; p-value: 0.001), household pig ownership (RR: 1.23; 95% CI: 1.02, 1.48; p-value: 0.030) and child pet contact (RR: 1.23; 95% CI: 1.09, 1.39; p-value: 0.001). Risk factors for ESBL-EC were dog ownership (RR: 1.35; 95% CI: 1.00, 1.83; p-value: 0.053), child pet contact (RR: 1.54; 95% CI: 1.10, 2.16; p-value: 0.012), and placing animal feces on household land/crops (RR: 1.63; 95% CI: 1.09, 2.46; p-value: 0.019). The primary limitations of this study are the use of proxy and self-reported exposure measures and the use of a single beta-lactamase drug (ceftazidime with clavulanic acid) in combination disk diffusion tests for ESBL confirmation, potentially underestimating phenotypic ESBL production among cephalosporin-resistant E. coli isolates. To improve ESBL determination, it is recommended to use 2 combination disk diffusion tests (ceftazidime with clavulanic acid and cefotaxime with clavulanic acid) for ESBL confirmatory testing. Future studies should also characterize transmission pathways by assessing antibiotic resistance in commercial food animals and environmental reservoirs. In this study, we observed an increase in enteric colonization of antibiotic-resistant bacteria among children with exposures to domestic animals and their waste in the household environment and children living in areas with a higher density of commercial food animal production operations.

The first fluorescent sensor for the detection of closantel in meat.

Closantel is widely used in the management of parasitic infestation in livestock, but is contraindicated in humans due to its high toxic to human retina. Thus, development of a fast and selective method for the detection of closantel residues in animal products is highly needed yet still challenging. In the present study, we report a supramolecular fluorescent sensor for closantel detection through a two-step screening process. The fluorescent sensor can detect closantel with a fast response (<10s), high sensitivity, and high selectivity. The limit of detection is 0.29ppm, which is much lower than the maximum residue level set by government. Moreover, the applicability of this sensor has been demonstrated in commercial drugs tablets, injection fluids, and real edible animal products (muscle, kidney, and liver). This work provides the first fluorescence analytical tool for accurate and selective determination of closantel, and may inspire more sensor design for food analysis.

Lagoon, Anaerobic Digestion, and Composting of Animal Manure Treatments Impact on Tetracycline Resistance Genes.

Increased demand for animal protein is met by increased food animal production resulting in large quantities of manure. Animal producers, therefore, need sustainable agricultural practices to protect environmental health. Large quantities of antimicrobials are used in commercial food animal production. Consequently, antimicrobial-resistant bacteria and the resistance genes emerge and are excreted through feces. Manure management is essential for the safe disposal of animal waste. Lagoons, with or without covers, and anaerobic digesters, with the primary purpose of methane production, and composting, with the primary purpose of producing organic fertilizer, are widely used methods of manure treatment. We reviewed manure management practices and their impact on tetracycline resistance genes. Lagoons are maintained at ambient temperatures; especially uncovered lagoons are the least effective in removing tetracycline resistance genes. However, some modifications can improve the performance of lagoons: sequential use of uncovered lagoons and the use of covered lagoons resulted in a one-log reduction, while post-treatments such as biofiltration following covered lagoon treatment resulted in 3.4 log reduction. Mesophilic digestion of animal manure did not have any significant effect; only a 0.7 log reduction in tet(A) was observed in one study. While thermophilic anaerobic digesters are effective, if properly operated, they are expensive for animal producers. Aerobic thermophilic composting is a promising technology if optimized with its economic benefits. Composting of raw animal manure can result in up to a 2.5 log reduction, and postdigestion composting can reduce tetracycline resistance gene concentration by >80%. In general, manure management was not designed to mitigate antimicrobial resistance; future research is needed to optimize the economic benefits of biogas or organic fertilizer on the one hand and for the mitigation of foodborne pathogens and antimicrobial resistance on the other.

Taurine as a Natural Antioxidant: From Direct Antioxidant Effects to Protective Action in Various Toxicological Models.

Natural antioxidants have received tremendous attention over the last 3 decades. At the same time, the attitude to free radicals is slowly changing, and their signalling role in adaptation to stress has recently received a lot of attention. Among many different antioxidants in the body, taurine (Tau), a sulphur-containing non-proteinogenic β-amino acid, is shown to have a special place as an important natural modulator of the antioxidant defence networks. Indeed, Tau is synthesised in most mammals and birds, and the Tau requirement is met by both synthesis and food/feed supply. From the analysis of recent data, it could be concluded that the direct antioxidant effect of Tau due to scavenging free radicals is limited and could be expected only in a few mammalian/avian tissues (e.g., heart and eye) with comparatively high (>15–20 mM) Tau concentrations. The stabilising effects of Tau on mitochondria, a prime site of free radical formation, are characterised and deserve more attention. Tau deficiency has been shown to compromise the electron transport chain in mitochondria and significantly increase free radical production. It seems likely that by maintaining the optimal Tau status of mitochondria, it is possible to control free radical production. Tau’s antioxidant protective action is of great importance in various stress conditions in human life, and is related to commercial animal and poultry production. In various in vitro and in vivo toxicological models, Tau showed AO protective effects. The membrane-stabilizing effects, inhibiting effects on ROS-producing enzymes, as well as the indirect AO effects of Tau via redox balance maintenance associated with the modulation of various transcription factors (e.g., Nrf2 and NF-κB) and vitagenes could also contribute to its protective action in stress conditions, and thus deserve more attention.

Probiotics and potential applications for alternative poultry production systems

Concerns over animal welfare continue to be a critical component of law and policies associated with commercial food animal production. Social and market pressures are the driving forces behind the legislation and result in the change of poultry production management systems. As a result, the movement toward cage-free and aviary-based egg production systems has become standard practices. Cage-based systems being replaced by alternative methods that offer a suitable housing environment to meet or exceed poultry welfare needs and require different management, including the ban of antibiotics in poultry diets. For broiler production, pasture- raised and free-range management systems have become more popular. However, challenges remain from exposure to disease-causing organisms and foodborne pathogens in these environments. Consequently, probiotics can be supplemented in poultry diets as commercial feed additives. The present review discusses the impacts of these probiotics on the performance of alternative poultry production systems for improving food safety and poultry health by mitigating pathogenic organisms and improving egg and meat quality and production.

Naturally Occurring Animal Coronaviruses as Models for Studying Highly Pathogenic Human Coronaviral Disease.

Coronaviruses (CoVs) comprise a large group of positive stranded RNA viruses that infect a diverse host range including birds and mammals. Infection with CoVs typically presents as mild to severe respiratory or enteric disease, but CoVs have the potential to cause significant morbidity or mortality in highly susceptible age groups. CoVs have exhibited a penchant for jumping species barriers throughout history with devastating effects. The emergence of highly pathogenic or infectious CoVs in humans over the past 20 years, including severe acute respiratory syndrome CoV (SARS-CoV), Middle East respiratory syndrome CoV (MERS-CoV), and most recently severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), underscores the significant threat that CoV spillovers pose to humans. Similar to the emergence of SARS-CoV-2, CoVs have been devastating to commercial animal production over the past century, including infectious bronchitis virus in poultry and bovine CoV, as well as the emergence and reemergence of multiple CoVs in swine including transmissible gastroenteritis virus, porcine epidemic diarrhea virus, and porcine deltacoronavirus. These naturally occurring animal CoV infections provide important examples for understanding CoV disease as many animal CoVs have complex pathogenesis similar to SARS-CoV-2 and can shed light on the ongoing SARS-CoV-2 outbreak. We provide an overview and update regarding selected existing animal CoVs and their primary host species, diseases caused by CoVs, how CoVs jump species, whether these CoVs pose an outbreak risk or risk to humans, and how we can mitigate these risks.

Regionalna specjalizacja produkcji rolnej w Polsce = Regional specjalization of agricultural production in Poland

Agricultural production is subject to continuous economic and structural changes. Since the 1990s economic and organizational factors have exerted greater influence on agricultural production than environmental conditions. An important determinant affecting farming production was Poland’s accession to the EU, where agriculture was covered by Common Agricultural Policy. Proportion of plant products does not go directly to the market; it is processed on farms into animal products. At the same time, however, what has been developing for years are unfavorable relations between crop and animal products. The reasons for this state of affairs are complex. One of the ways to improve the results of agricultural production is specialization. This is quite a broad concept, embracing the research issue concerning agricultural production structure and directions of agricultural production, especially regarding commercial production which are defined in literature as directions of agricultural specialization (Kulikowski 2003). The aim of the study is to present changes in the regional specialization of crop and livestock production taking place in Poland in the years 2004‑2019. An attempt was made to answer the question in which agricultural production does a given region specialize and to what extent? The following research hypothesis was adopted: changes in the specialization of agricultural production in the regions are influenced by farmers benefiting from direct payments and other forms of financial aid under the Common Agricultural Policy. For the research on the regional specialization of agricultural production, the location quotient based on the share of crop and livestock commodity production in commodity production was used. The location quotient, apart from providing a static picture of the situation for comparative analyzes, allows for comparisons with regard to the dynamics of the specialization index, and to indicate differences in the dynamics of changes in individual agricultural production specializations. In the investigated period, crop production which is more dependent on climate conditions than animal breeding was much more diversified (changed over time). Western voivodships achieved a high level of specialization in plant production. It resulted from the agrarian structure of these regions, where large farms dominated. The lack of specialization in plant production was typical of the following voivodships: Podlaskie, Warmińsko-mazurskie and Wielkopolskie. With regard to animal production, the situation was different. The share of commercial animal production in the general commercial output was primarily affected by an apparent increase in the share of commercial milk production. This concerned north-eastern voivodships: Podlaskie and Warmińsko-mazurskie, which specialized in beef production as well. Wielkopolskie Voivodship also reached a high level of specialization not only in beef but mainly in pork production.

The Effect of Probiotics on High Fiber Diet in Rumen Fermentation Characteristics

The productivity of cattle must be achieved through feed efficiency which has strong correlation with the rumen work. The efforts to increase productivity of cattle can use probiotics as feed additive in animal feeding. Probiotics are increasingly used in commercial animal production operations to profitably alter the gastrointestinal flora, thus improving animal health and productivity. This study aimed to investigate the effects of different type of probiotics on high fiber diet in live weight change, rumen fermentation, the total rumen of bacteria, and the total of lactic acid bacteria. Three fistulated cattle received a daily ration 2% from body weight (DM) of Pennisetum purpureum (70% of DM), concentrates (30% of DM), and mineral mix (1% of DM). The experiment was arranged as a crossover design with six treatments and three sampling periods as replications. The treatments were (R0) control diet, (R1) control diet + 10 mL of Lactobacillus plantarum TSD-10 per day, (R2) control diet + 10 mL of L. plantarum MX-16 per day, (R3) control diet + 10 mL of L. brevis SPCE-39 per day, (R4) control diet + 10 mL of mix Lactobacillus plantarum TSD-10, L. plantarum MX-16, and L. brevis SPCE-39 per day, (R5) control diet + 10 mL of commercial probiotics per day. Neither pH nor the total of lactic acid bacteria (LAB) were significantly affected by the treatment. Among others treatment, R3 showed a tendency body weight gain. The total of rumen bacteria was affected significantly for R2, R3, R4, and R5 compared with R0. The acetate to propionate ratio were affected for R3, R4, and R5, but were not affected significantly for R2 and R3 compared with R0. The butyrate ratio and rumen ammonia concentration were not affected by the treatment. In conclusion, probiotics change the population of the rumen bacteria. In addition, based on metabolism characteristics, particularly on propionate production and C2/C3 ratio, R3 was shown the best probiotics candidate on high fiber diet. Nevertheless, the difference pattern in volatile fatty acid indicates that different mechanisms may be involved.

RETRACTED ARTICLE: Antibiotic growth promoters virginiamycin and bacitracin methylene disalicylate alter the chicken intestinal metabolome

Although dietary antibiotic growth promoters have long been used to increase growth performance in commercial food animal production, the biochemical details associated with these effects remain poorly defined. A metabolomics approach was used to characterize and identify the biochemical compounds present in the intestine of broiler chickens fed a standard, unsupplemented diet or a diet supplemented with the antibiotic growth promoters, virginiamycin or bacitracin methylene disalicylate. Compared with unsupplemented controls, the levels of 218 biochemicals were altered (156 increased, 62 decreased) in chickens given the virginiamycin-supplemented diet, while 119 were altered (96 increased, 23 decreased) with the bacitracin-supplemented diet. When compared between antibiotic-supplemented groups, 79 chemicals were altered (43 increased, 36 decreased) in virginiamycin- vs. bacitracin-supplemented chickens. The changes in the levels of intestinal biochemicals provided a distinctive biochemical signature unique to each antibiotic-supplemented group. These biochemical signatures were characterized by increases in the levels of metabolites of amino acids (e.g. 5-hydroxylysine, 2-aminoadipate, 5-hydroxyindoleaceate, 7-hydroxyindole sulfate), fatty acids (e.g. oleate/vaccenate, eicosapentaenoate, 16-hydroxypalmitate, stearate), nucleosides (e.g. inosine, N6-methyladenosine), and vitamins (e.g. nicotinamide). These results provide the framework for future studies to identify natural chemical compounds to improve poultry growth performance without the use of in-feed antibiotics.

Direct analysis in real time-Mass spectrometry (DART-MS) in forensic and security applications.

Over the last decade, direct analysis in real time (DART) has emerged as a viable method for fast, easy, and reliable "ambient ionization" for forensic analysis. The ability of DART to generate ions from chemicals that might be present at the scene of a criminal activity, whether they are in the gas, liquid, or solid phase, with limited sample preparation has made the technology a useful analytical tool in numerous forensic applications. This review paper summarizes many of those applications, ranging from the analysis of trace evidence to security applications, with a focus on providing the forensic scientist with a resource for developing their own applications. The most common uses for DART in forensics are in studying seized drugs, drugs of abuse and their metabolites, bulk and detonated explosives, toxic chemicals, chemical warfare agents, inks and dyes, and commercial plant and animal products that have been adulterated for economic gain. This review is meant to complement recent reviews that have described the fundamentals of the ionization mechanism and the general use of DART. We describe a wide range of forensic applications beyond the field of analyzing drugs of abuse, which dominates the literature, including common experimental and data analysis methods. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 37:171-187, 2018.

Feet, heat and scallops: what is the cost of anthropogenic disturbance in bivalve aquaculture?

The effects of unnatural disturbances on the behaviour and energetics of animals are an important issue for conservation and commercial animal production. Biologging enables estimation of the energy costs of these disturbances, but not specifically the effect these costs have on growth; a key outcome measure for animal farming enterprises. We looked at how natural and anthropogenically induced activity and energy expenditure of king scallops Pecten maximus varies with temperature. These data were then used to model growth time of king scallops reared in an aquaculture facility under different temperatures and anthropogenic disturbance levels. The scallops exhibited a typical total metabolic rate (MR)–temperature curve, with a peak reached at a middling temperature. The percentage of their total MR associated with spinning and swimming, behavioural responses to disturbance, was considerable. Interestingly, as temperature increased, the activity MR associated with a given level of activity decreased; a hitherto unreported relationship in any species. The model results suggest there is a trade-off in the ambient temperature that should be set by hatcheries between the optimal for scallop growth if completely undisturbed versus mitigating against the energy costs elicited by anthropogenic disturbance. Furthermore, the model indicates that this trade-off is affected by scallop size. Aquaculture facilities typically have controls to limit the impact of human activities, yet the present data indicate that hatcheries may be advised to consider whether more controls could further decrease extraneous scallop behaviours, resulting in enhanced scallop yields and improved financial margins.

Is Capitalism to Blame? Animal Lives in the Marketplace

Abstract Increasing efficient production of commercial animal products has resulted in decreased quality of life and shorter life spans for animals being farmed and bred. Should this animal welfareproblem be blamed on farmers or consumers? Or should we blame the capitalist system? I argue that those elements that make the market economy successful also result in poor outcomes for animals in the system. Understanding the way in which capitalism is the problem allows us to think clearly about what reforms are necessary to improve the lives of nonhuman animals.

The Use of Probiotics in Animal Nutrition

This paper reviewed issues regarding the use of probiotics (feed additive) in animal feeding. Probiotics are increasingly used in commercial animal production operations to advantageously alter gastrointestinal flora, thereby improving animal health and productivity. The major outcomes from using probiotics include improvement in growth, reduction in mortality, and improvement in feed conversion efficiency. Although it is not well defined, the mechanisms of probiotics activity to achieve their role include alteration in intestinal flora, enhancement of growth of nonpathogenic bacteria, forming lactic acid and hydrogen peroxide, suppression of growth of intestinal pathogens, and enhancement of digestion and utilization of nutrients. Different probiotics contain different microorganisms which may behave differently, as probiotics are not single entities. It has been indicated that multi-strain preparation is highly efficient in animal feeding. Finally, the efficacy of probiotics have been found to be variable depending on survival rate and stabilities of strains, doses, frequency of administration, interactions with some medicines, health and nutritional status of the animal and the effect of age, stress and genetics of animals.

Attitudes of Canadian citizens toward farm animal welfare: A qualitative study

As part of a larger project to determine if there are animal-welfare-related values shared by some commercial food–animal producers and non-producers in Canada, open-ended, semi-structured interviews were conducted to elicit opinions about animal welfare among 24 urban and rural residents not involved in commercial animal production. All participants possessed a self-described interest in food animal well-being and were therefore assumed to represent the views of Canadian non-producers most apt to engage in efforts to shape the animal welfare policies of governments and businesses. Participants described animal welfare in moral or ethical terms, expressed virtually unanimous support for animals having access to “natural” living conditions, and (somewhat less often) linked animal welfare to positive affective states. Maintaining reasonable health and biological functioning was seen as important but was not to take precedence over the benefits of natural living. Participants favoured small family farms and unanimously objected to confinement housing. Participants did, however, offer qualified support for intensive practices and were unanimous in not assigning blame to producers, whom they regarded sympathetically. Predictably perhaps, given our sample, most were critical of industries preoccupied with profits and of consumers who unthinkingly seek cheap food. Recommended ways of improving welfare included instilling in consumers a greater appreciation for the intrinsic value of humanely reared animals, and better education of children regarding the connection between animals and food. Disagreements arose over the welfare implications of organic production and approaches to animal advocacy. Differing demographic backgrounds, experiential involvement with food animals and knowledge of food animal production practices may have influenced the nature or specificity of welfare concerns. Many participants admitted a lack of knowledge about contemporary production practices and some expressed an interest in obtaining additional knowledge. These findings contribute to a broader effort to identify shared values among different stakeholder groups as a basis for formulating widely acceptable, farm animal care and handling polices.

Quantifying atmospheric stability conditions at a swine facility and an adjacent corn field in Iowa, USA

Atmospheric stability conditions in the atmospheric surface layer control the distance and direction of transport of air contaminants. Near confined animal facilities, transport processes significantly impact air quality as these sites typically act as point sources of dust and odor constituents; however, little information is available on atmospheric stability effects. This study was conducted to assess year-round temporal patterns of atmospheric stability at a swine production facility and an adjacent commercial corn field (CF) in the US Midwest. Two towers of 10 and 20 m heights for continuous micrometeorological measurements were deployed within a CF and between swine buildings (BSB), respectively. Each tower was equipped with an eddy-covariance system at 6.8 m height, infrared thermometers, and six cup anemometers with thermocouples installed at log-distributed heights. Overall results from gradient Richardson number and Monin–Obukhov (z/L) calculations revealed a greater prevalence of unstable conditions for BSB compared with CF. During the 13-month measurement period, unstable cases (z/L ranging from −1 to −0.01) occurred 1.4 times more frequently for BSB than CF (52 vs. 39%, respectively), while stable cases (0.011–0.2) were 1.8 times more frequent for CF than BSB (24 vs. 14%, respectively). These patterns were partly associated with higher surface radiometric temperatures for BSB. Relatively greater diurnal heat capture at BSB (ground and roof surfaces) and a cooling effect in CF through active canopy transpiration during the daytime explain these z/L and radiometric temperature results. Prevalent diurnal atmospheric instability at BSB suggests enhanced ascendant vertical transport of air pollutants perhaps causing greater mixing/dilution with the atmospheric layer and/or their facilitated transport over greater distances when sorbed onto particles. This enhanced understanding of the spatio-temporal patterns of atmospheric stability can be subsequently applied in further studies for identifying effective odor mitigation strategies near commercial animal production facilities.

Nitrofurans' residues in food of animal origin

Nitrofurans are synthetic broad-spectrum antimicobial agents that are often used in commercial animal production because of their excellent antibacterial and pharmacokinetic properties. However, nitrofurans and their metabolites have been shown to have potentially carcinogenic and mutagenic characteristics which has led to a ban on the use of nitrofurans in preventive and therapeutic treatment of animals used for food production. Metabolites of nitrofurans that can be determined after their application are: a metabolite of furazolidone, furaltadone metabolite, a metabolite of nitrofurantoin and nitrofurazone metabolite. The presence of residues of nitrofuran antibiotics in meat, fish and shrimps, and milk and eggs originating from countries outside the European Union is monitored and recorded by the RASFF system of the European Union. Furthermore, since nitrofurans are used in some countries as prophylactic agents and growth promoters, it is necessary to carry out constant control of various types of food of animal origin, in order to reduce to the minimum potential carcinogenic and mutagenic effects of these supstances for the health of consumers. In Bosnia and Herzegovina, there is no permanent control of nitrofurans in food of animal origin. The provisions of the ?Regulation on the maximum allowable amounts of veterinary drugs and pesticides in products of animal origin", published in the Official Gazette of Bosnia and Herzegovina state the prohibiting of the use of certain veterinary drugs in animals intended for human consumption, including nitrofurans. The European Union has established the minimum required limit (MRLP) for performance which is 1 ?g/kg of nitrofurans for edible tissues of animal origin. Taking all this into account, methods for nitrofurans detection should be accreditated and validated, both for screening and confirmatory methods, and further research into the presence of nitrofurans in food of animal origin in Bosnia and Herzegovina should be performed.

Investigating Contemporary Evolution via Size-Selective Harvest

[ILLUSTRATION OMITTED] Evolution is commonly taught as a slow process that changes gene frequencies over long time periods. These genotypes are changed through natural selection on phenotypes with the fittest individuals spreading more genes into the environment than less-fit phenotypes. What is now well known to science, but still under- emphasized in textbooks and classroom lessons, is that humans can be one of the strongest selection agents on an organism's phenotype through several different pathways. Humans have perhaps the longest history of affecting organism phenotypes through size-selective harvest, or collection of the largest organism. This activity was designed to supplement traditional evolution units and allow students to discover that evolution can occur in relatively short time-periods and be directed by human action. After completing this activity, students will be able to: * predict the consequences of selective harvesting * understand how evolution and natural selection affect genotypes and phenotypes * design and critique experimental design * collect and analyze data * make conclusions based on research results. Students are likely most familiar with size-selective harvest in trophy hunting of large mammals, such as deer. However, marine fisheries are probably the most common arena for size-selective harvest based upon common industry practices. For centuries, fishermen have used large nets pulled through schools of fish to maximize their catch-per-unit effort. In modern times, large commercial fishing fleets use sophisticated technology, including global positioning satellites and sonar, in conjunction with traditional knowledge about behavior and biology to locate the largest concentrations of fish. Nets are still used to haul in the fish and require fish to be of a certain size to be captured. Even with smaller mesh sizes, some fish will escape, but this is less so in the modern era of commercial fisheries. Fish often mature at a genetically-determined size and/or age, which in turn is structured by environmental conditions. These types of traits are called Life History Traits. Growth is highly correlated with age, and older individuals are usually larger. Generally speaking, the larger the mother, the more offspring she will have with each reproductive event. If she is sufficiently large, her offspring will also be larger. These larger offspring often have higher survival rates than small offspring. Darwinian fitness is related to the proportion of the parents' genes in the next generation; fitness is generically the number of offspring you have that live to reproduce. Larger female fish have higher fitness than smaller female fish. Darwin (2004) used changes seen with selective breeding of animals as evidence of natural selection. Selective breeding is common in today's commercial agriculture and food animal production, but is seldom discussed with relevancy to evolutionary processes. Humans can also inadvertently affect the evolution of species. Using the marine fisheries example, fish that escape fishing nets to reproduce are often smaller and thus pass on genes that allow maturity at smaller sizes. If the harvest is strong enough, or repeated over many generations, this selection can result in fish being smaller at maturity (Figure 1). This has fitness consequences and reduces biomass in commercial harvests (Conover & Munch, 2002; Hutchings, 2005). Contemporary evolution is defined as heritable trait evolution observed in contemporary time (i.e., less then a few hundred years) (Stockwell et al., 2003). [FIGURE 1 OMITTED] A simple laboratory exercise using inexpensive and nonperishable materials can demonstrate contemporary evolution. The following activity will allow students to discover how humans can interfere with the natural selection of organisms and do so in relatively little time. …

Characterising Forages for Ruminant Feeding

Forages are the most important feed resource for ruminants worldwide, whether fed as pastures, forage crops or conserved hay, silage or haylage. There is large variability in the quality of forages so measurement and prediction of feeding value and nutritive value are essential for high levels of production. Within a commercial animal production system, methods of prediction must be inexpensive and rapid. At least 50% of the variation in feeding value of forages is due to variation in voluntary feed intake. Identification of the factors that constrain voluntary feed intake allows these differences to be managed and exploited in forage selection. Constraints to intake have been predicted using combinations of metabolic and physical factors within the animal while simple measurements such as the energy required to shear the plant material are related to constraints to intake with some plant material. Animals respond to both pre- and post-ingestive feedback signals from forages. Pre-ingestive signals may play a role in intake with signals including taste, odour and texture together with learned aversions to nutrients or toxins (post-ingestive feedback signals). The challenge to forage evaluation is identification of the factors which are most important contributors to these feedback signals. Empirical models incorporating chemical composition are also widely used. The models tend to be useful within the ranges of the datasets used in their development but none can claim to have universal application. Mechanistic models are becoming increasingly complex and sophisticated and incorporate both feed characteristics and use of biochemical pathways within the animal. Improvement in utilisation through the deliberate selection of pasture plants for high feeding value appears to have potential and has been poorly exploited. Use of Near Infrared Reflectance Spectroscopy is a simple method that offers significant potential for the preliminary screening of plants with genetic differences in feeding value. Near Infrared Reflectance Spectroscopy will only be as reliable as the calibration sets from which the equations are generated. (Asian-Aust. J. Anim. Sci. 2003. Vol. 16, No. 1 : 116-123)