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Background: Brucellosis produces losses in livestock raising in the Americas. This region reports prevalence variations associated with the implementation of control programs, thus requiring an analysis that permits the combination of results to reach conclusions, which may be conducted through meta-analysis. Aim. To estimate the combined prevalence of Brucellosis in Cattle and Buffaloes in Central America and the Caribbean, and South America in the 2010-2021 period, and to analyze the different time performances in all the regions and the species. Materials and methods: Several papers published in electronic databases, such as PubMed / PubMed Central, Science Direct, Scielo, Ebsco, and Google Scholar were selected. Original papers and postgraduate theses available were included, provided they offered information about cattle and buffaloes, using the serological techniques recommended by the World Animal Health Organization, and which provided the sample size and the number of positives. A meta-analysis was done to estimate the combined prevalence of the disease, and the effect on the subgroups was evaluated by meta-regression. Results: Overall, 65 that met the selection criteria were included, 56 related to cattle, and 11 to buffaloes. The combined prevalence was 3.0%; differences between cattle (2.7%) and buffaloes (5.2%) were observed. The differences between the periods studied accounted for 4.3% (2011-2016) and 2.0% (2017-2021), respectively. Conclusions: The combined prevalence of the disease was 3.0%, which was higher in buffaloes, which dropped in the last five years. No differences were observed between the two regions studied. [ABSTRACT FROM AUTHOR]

Introduction: Given its importance in evaluating the digestibility of ruminant foods for ruminants, the paper aimed to bring information on some general aspects of the in vitro gas production technique and refers to the uses that are given to it. Development: The origins of the technique date back to the work in 1979. Since then there have been changes in the way it is applied, maintaining the essence of measuring the gas production that occurs when the sample is inoculated with rumen fluid, feces or enzymes in a buffered mineral medium based on bicarbonates that releases an amount of gas proportional to the volatile fatty acids produced. The way in which the amount of gas is measured has changed till the now mainly used transducers that are coupled to computers. The technique has been used for multiple studies that were reviewed, as well as some works dedicated to its improvement based on difficulties that arose. Conclusions: It is concluded that the in vitro gas production technique is probably the most versatile tool for measuring digestibility; it presents didactic and accessible procedures; entails fewer costs and also represents a more compatible alternative for animal welfare legislation, by using voided feces as inoculum and that still needs more to be done in order to achieve better precision and accuracy, and the possible application in other fields of animal food evaluation. [ABSTRACT FROM AUTHOR]

Background: Forage and feedstuff technologies with additives contributed to more efficient nutrition of herbivores. Aim. To evaluate the microbial content of feces from covies fed with forages and feedstuffs containing various levels of oregano. Materials and methods: This paper comprised two studies, one on El Romeral Farm, Guachapala Canton, the University of Cuenca, located on S 2o45'54", W 78o42'58", 2 254 m above sea level; and another at Molihers food processing factory, in Ochoa Leon, on S 2o49'48", W 78o59'12", 2 600 m above sea level. The control (T1) consisted of feeds for covies (Molihers); the other treatment (T2) was based on Phytogenics, at a rate of 2 kg/ton. Treatment 3 (T3), used phytogenics (3 kg/ton); whereas treatment 4 (T4) contained phytogenics (5 kg/ton). all the treatments contained 13.5% protein. A completely randomized experimental design was used, along with one-way ANOVA. The microbiological composition of feces was measured. Results: The fecal bacterial burden was reduced (P <0.05) using oregano, in comparison to the control. Conclusions: The nutrition of covies using alfalfa and feeds containing phytogenic additives such as oregano at 3 and 4 kg/t doses of the feed proved effective, the bacterial and parasitic counts in the feces were reduced due to the organic principles in the oregano supplemented. [ABSTRACT FROM AUTHOR]

Background: Forage and feedstuff technologies with additives contributed to more efficient nutrition of herbivores. Aim. To evaluate the productive performance and organoleptic quality of meat from covies fed forages and feedstuffs containing various levels of oregano. Methods: This paper consisted of two studies, one on El Romeral Farm, Guachapala Canton, the University of Cuenca, located on S 2o45'54", W 78o42'58", 2 254 m above sea level. Another study was developed in sheds belonging to Molihers food processing factory in Ochoa Leon, on S 2o49'48", W 78o59'12", 2 600 m above sea level. The control (T1) consisted of feeds for covies (Molihers); the other treatment (T2) relied on phytogenics at a rate of 2 kg/ton. Treatment 3 (T3) used phytogenics (3 kg/ton), whereas treatment 4 (T4) contained phytogenic products (5 kg/ton). All the treatments had 13.5% protein. A completely randomized experimental design was used, along with one-way ANOVA. The final weight was measured after 115 days. Results: No significant differences were found between the treatments for the final weight in the two trials. There were no differences in the organoleptic quality indexes, except for the color and crust for the Molihers in T3 and T4. Conclusions: The nutrition of covies using alfalfa and feeds containing phytogenic product additives such as oregano at 3 and 4 kg. t dose of the feed proved effective. The final weights were similar to the control animals, and the organoleptic characteristics of meat were not affected, due to the organic principles in the oregano supplemented. [ABSTRACT FROM AUTHOR]

Background: Chromatography permits chemical components' separation, identification, and quantification in complex mixtures. Chromatographic methods have various applications, which include the determination of an agrochemical solvent percentage and its utilization in the food-processing industry. High-Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC) are essential for agriculture. Both types are used in numerous research studies today thanks to their versatility, sensitivity, reproducibility, and quickness. Aim: To discuss the main results of studies that include GC and HPLC in agriculture. Materials and methods: The study relied on a compilation of recent papers, where these techniques play a critical role in this area of science. Results: The utilization of GC and HPLC in agriculture contributed to relevant results, from the analysis of fatty acids profile in the formulation of a diet for animal nutrition, to the determination and quantification of agrochemical residues in plants, the detection of contaminants in the diets, and drug residues that compromise the lives of animals. Conclusions: The use of chromatography is an essential methodology for biochemical, toxicological, structural, and agro-industrial studies. [ABSTRACT FROM AUTHOR]

Background: Some diet additives have become alternatives to achieve higher yields within the productively sustainable, organic, and ecological margins. Hence, nutrients and microorganisms can be added to the diet for fish immunity improvements, by using the nutrients in the feed, which lead to a positive animal performance. Accordingly, the aim of this paper was to gather information related to the utilization of additives as immunostimulant in tilapia (Oreochromis ssp.), and their physiological performance in the body. Development: Many of these immunostimulants are microorganisms or habitual nutrients in the diet, such as polysaccharides, proteins or lipids, which at high concentrations are capable of creating a stimulating effect, speeding disease resistance through specific or unspecific mechanisms of immunological response, thus becoming primary prophylactic agents. Conclusions: The use of additives as immunostimulants helps prevent the occurrence of common diseases in tilapia culture, by modulating the intestinal system in the different species of genus Oreochromis, thus enhancing the unspecific immune response, and, in turn, some processes like individual growth, feeding efficiency, and stress tolerance can be favored. [ABSTRACT FROM AUTHOR]

Background: The final antisepsis of nipples is performed with aqueous solutions containing Propolina® to prevent mastitis. The aim of this paper was to determine the antimicrobial activity of different concentrations of Propolina® against mastitis-causing microorganisms. Materials and Methods The microorganisms were isolated from the milk of cows having three mastitis crossings. The antimicrobial activity of aqueous Propolina® solutions between 2.5 and 60.0 mg.ml-1 was tested against isolated bacteria and Gram-negative Escherichia coli strain ATCC 25922 by spraying the solution in plate wells containing agar. A one-way ANOVA was used to determine the effect of the propoline dose on the bacterial species associated with mastitis; the Duncan’s multiple rank-sum test was used for dose comparisons. Results: The Gram-positive bacteria were identified: Staphylococcus aureus, coagulase-negative Staphylococcus sp. and Corynebacterium sp., which were sensitive to the Propolina® solutions, while Gram negative Escherichia coli strain ATCC 25922 showed no sensitivity. The 60, 30, and 20 mg.ml-1 concentrations were more effective against Staphylococcus aureus and coagulase-negative Staphylococcus spp. Conclusions: Staphylococcus aureus, coagulase-negative Staphylococcus sp., and Corynebacterium sp. were isolated and identified, as causing subclinical mastitis. The Propolina® solutions were highly effective against Gram positive bacteria Staphylococcus aureus and coagulase-negative Staphylococcus sp., which were sensitive to the 20, 30, and 60 mg.ml-1, and 30 and 60 mg.ml-1 concentrations of Propolina®, respectively. [ABSTRACT FROM AUTHOR]

Background: Fetal programming was a term used first in humans, then it spread thanks to different research done on domestic animals to determine the effects on the progenies of nutrition during the early, intermediate, and final stages of gestation, and their short-term repercussions on the productive, reproductive, and immunological parameters, such as birth and weaning weights. Aim: To present this concept and analyze birth and weaning weights as reference information for buffalo progenies. Development: This paper deals with the concept of fetal programming and its impact on raising; the weight-related data collected upon buffalo calving were shown. Conclusions: The scientific evidence demonstrated the relevance of the nutritional state of the cows during fertilization and gestation, as well as the low weaning weights of the progenies. It means that a change of mindset is necessary in livestock raising, by considering this scenario as a starting point to produce offspring with the proper weight required for further production and reproduction. [ABSTRACT FROM AUTHOR]

Background. One of the reasons to study infectious diseases is to increase their control and eradication. Mathematical models could be a powerful tool to achieve that end, which allows for optimization of limited resources, and conduct more effective measures; these models are made to predict and increase understanding of the studied phenomenon. The aim of this paper is to conduct simulations using the stochastic model known as Susceptible, Infected, Recovered (SIR), and introduce them in the curricula of students, epizootiological analyses, and decision-making. Methods. Virtually the entrance of ten migrating birds with respiratory processes was simulated on bird rearing farms averaging 5000 free-range poultry from different types. The R0 was determined depending on the incidence. Results. Simulation was run with a low communicability index (1.8 %), that is, 1.8 out of every 100 birds get sick, after interacting with other 5 birds each, at random, for 10 days. In the absence of intervention, there would be a spike of sick animals at 20 days, surpassing 3000 birds. A basic reproductive number greater than the unit (R0=1.14) was observed, thus qualifying as an epidemic outbreak. Conclusions. A number of simulations were made using the stochastic model with a sustainable analytical tool based on an R-free program. The need to integrate the epizootiology, epidemiology, and mathematic was demonstrated, suggesting that appropriate training should be provided by competent professionals. [ABSTRACT FROM AUTHOR]

Background: Technical efficiency (TE) refers to the ability of obtaining the highest possible amount of products, depending on production and technology factors. Aim: The aim of this paper was to review the effect of factors like labor, geographical location, and farm size on the TE of dairy systems. Development: Document review was conducted to study factors such as labor, geographical location, and farm dimensions, and the influence of these factors on technical efficiency (TE) in dairy systems. An evolution in the increase of total cows and the number of TE in dairy systems has been reported, regarding the existing relation with location, labor, and herd size. Studies of farm size and total cows showed a positive relation with ET, which suggested that large dairy farms have higher TE than smaller farms; however, the size-efficiency ratio does not look very strong. Conclusions: The relation of technical efficiency with labor, technical training, and rural extension in differential mode, were observed. However, no significantly sustained relation was observed between farm dimensions and technical efficiency in several countries and by different kinds of farmers, showing a negative relation with efficiency and farm size in some. This might also reflect the additional complexity of allocating more resources and accomplishing technical efficiency at different scales. [ABSTRACT FROM AUTHOR]

Background: Crop-cattle farms in the lower basin of Guayas River are different in terms of their chances to maintain animals throughout the year. The aim of this paper is to evaluate forage balance of crop-cattle farms in the lower basin of the river. Method: This research included 76 farms in the lower Basin of Rio Guayas, Ecuador. A number of 12 variables were selected; the input variables were used to classify the farms into four types through k-mean cluster analysis. The annual percentage of nutritional needs met on the farm was considered as well. The output variables produced the central trend and dispersion statistics, which were related to the types achieved. A simple correlation analysis was performed between the input and output variables using the Spearman coefficient. Results: Most cases were observed in the low typology (36), along with the lowest percentage of the cattle raising area, stocking rate, and days on the farm. The mid-low and mid-high typologies produced similar values as to stocking rate and the days the animals were under such conditions; the high typology kept the animals for more days, with adequate stocking rates and positive forage balance. Conclusions: The forage balance was positive in the high typology, with better utilization of resources produced and introduced for animal nutrition, and more days on the farm. [ABSTRACT FROM AUTHOR]

Background: Worldwide, goats have always been linked to man, mainly due to the quality of their production of meat, milk, and wool. The aim of this paper is to present the general characteristics of household systems for goat production in the municipality of Camagüey, Cuba. Methods: A survey was applied to 46 household farmers in urban and suburban areas of the city of Camagüey, Cuba. Descriptive statistics was used in the study, along with hierarchical clustering for system classification. Results: All the farmers are over 20 years of age, predominantly males with secondary education, on average. Overall, 54.3% of them does not own or is leasing land, and 47.8% works independently from any organizations; the rest belongs to a few cooperatives. The farmers have access to little input and investment funds, and their labor is framed within their households, without salaries; their main way of sustenance is not goat breeding. The herds comprised between 1 and 54 goats, of which 27.5% are milking females. The systems were classified into three types, considering the total of goats, grazing hours, milking goats, years of experience, educational level, and family members engaged in the activity. The first group showed a higher educational level, longer grazing time, and a larger number of animals; the second averaged 5 hours of grazing and eighth grade of education. The indicators in these two groups were higher than in the third group. Conclusions: Household goat production systems were characterized in the municipality of Camagüey, which will contribute to more strategic work projects that promote local sustainable development. [ABSTRACT FROM AUTHOR]

Background: Honey bees are threatened by acaride Varroa destructor, which among other factors, causes what is known today in the world as Colony Collapse Disorder. The aim of this review is to publish updated information of Varroasis in Apis mellifera, as well as to study some defense mechanisms of bees during their co-evolution with the parasite. Methods: The databases of Sciencedirect, Google-scholar, Scopus, and NCBI were reviewed under the following key words: Varroa destructor, biological cycle, bees, Apis, Africanized bees, apiculture, and Apis mellifera. Special emphasis was paid to papers published within the last five years. Results: The features of the acaride and its biological cycle, its effects on bee colonies, and the factors that favor the presence of the parasite were described. Moreover, mechanisms like hygienic behavior, grooming, and suppression of acaride reproduction. The impact of Varroasis worldwide was updated. Conclusions: Certain bee populations manage to live with acaride varroa, because their defense mechanisms allow for infestation rates at permissible ranges. The current trend is to include these mechanisms in breeding programs. [ABSTRACT FROM AUTHOR]

This paper describes for the first time the generation of the K88ab-GnRH hybrid fimbriae, the fusion of N. meningitidis P64k protein (P64k-GnRH), and its evaluation as vaccine candidates to control fertility in mammals. Twenty hybrid male pigs were randomly distributed in four groups: placebos and immunized with K88ab-GnRH, P64k- GnRH and a GnRH analogue (GnRHm1), linked to a tetanus toxoid (TT) T-helper epitope (positive control), respectively. The pigs were immunized at 9-10 weeks of age, using a two-dose scheme, and were sacrificed sixteen weeks later. K88ab-GnRH, P64k-GnRH, and GnRHm1-TT induced higher, similar, and lower testosterone levels in the serum, compared to the placebo, respectively. In the K88ab-GnRH group, the pigs underwent a reduction in testicle size and weight (P  0.01), and the weight of epididymes compared to the placebo; none of them was able to ejaculate. In the P64k-GnRH group, the pigs had a reduction in testicle weight (P  0.05), and only one of them was able to ejaculate. The testicles of the pigs immunized with K88ab-GnRH and P64k-GnRH showed structural and functional damage; spermatogenesis was also affected. The accessory sexual glands of the P64k-GnRH group were normal, in contrast to K88ab-GnRH, where interstitial fibrosis was observed. The damage caused by K88ab-GnRH and P64k-GnRH in the target organs evaluated were in all cases lower than the affectations caused by the GnRHm1-TT peptide. [ABSTRACT FROM AUTHOR]

The aim of this paper was to evaluate the effects of a strategy of changes to manage the bio-economic efficiency of a Murrah Buffalo production system in the province of Camagüey, Cuba, located 210 north and 770 west, 217 meters above sea level. The climate is tropical humid (Aw) plain. The mean annual precipitations average 1 180 mm (71 % between May and October), and temperature is between 24 and 29° C. The local soil is carbonated brown, brown without carbonates, and reddish-brown fersiallitic. The system comprises 5 100 ha and has 536 workers/year. A strategy to introduce management changes in agro-technology, food, reproduction, replacement, health, salary policies, and training was implemented as part of an innovation package with a systemic and participatory approach. The evaluation lasted eight years, and it was critical to increase dairy production in more than 200 000 kg/year in 2012, in comparison to 2004, with improvements in natality and reduction of operational expenses of the system. It was concluded that the strategy had a determining effect on the system's indicators. [ABSTRACT FROM AUTHOR]

The aim of this paper was to compare the effects of two superovulation protocols: synchronization of the follicular wave (SFW), and natural estrus (NE) induction of embryos produced for transference in Holstein cows. Twenty cows were chosen as donors, with body condition (BC) of 2.75-3.5; 40-60 months old; 1-2 previous services per gestation, and without reproductive problems. Two superovulation protocols were applied: SFW and NE. SFW was not observed to produce more embryos than the NE in the blastocyst and morula stages. [ABSTRACT FROM AUTHOR]

The aim of this paper was to evaluate the reproductive behavior of female Zebú and 5/8 Zebu x 3/8 Simmental on a genetic farm in the central region of Cuba. The research was made between 2010 and 2014. The individual records of 255 cows; 200 Zebus (106 White and 94 Bermeja) and 55 crossbreds (5/8 Zebu x 3/8 Simmental) were included. The calving-first insemination interval (CFI) and calving-gestation interval (CGI), inter-calving period (ICP), and service per gestation (S/G) were calculated. Besides, the effects of genotype, parity, quarter and year of calving were evaluated using the above indicators. The descriptive stratigraphy was calculated, and a general linear model was used to determine the effects of each variation source. The three genotypes showed low reproductive efficiency, though slightly more favorable for 5/8 Zebu x 3/8 Simmental. The calving year, genotype, and parity influenced (P < 0.05) the CFI, CGI, and ICP. The calving quarter only influenced (P < 0.05) the CGI. The gestation service was not influenced by any factor. It was concluded that the three genotypes studied underwent high deterioration of reproductive indicators, influenced by the genotype, quarter, calving year, and parity. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to make a contribution to environmental arrangement of the livestock potential in the municipality of Jimaguayú, Camagüey, Cuba. The indicators, restrictions, categories and conflicts of livestock potential in the region were identified and located on a map. Additionally, the policies, guidelines, regulations, and standards for proper environmental management in each livestock raising area were determined. The study concluded that the potential of livestock raising depends on the environmental use recommended as principal in eight of the seventeen secondary environmental areas that make up the region; one of them was considered for secondary use. In terms of categories, the municipality comprises 126.9 km2 with inexistent livestock potential, including several settlements and water reservoirs; 115.7 km2 showed a poor potential; 316.3 km2 had a mid-potential; and 225.4 km2 was high. The previous contributed to proper environmental arrangement of livestock potential in the municipality of Jimaguayú, Camagüey. In accordance with it, restrictions, indicators, categories and conflicts observed in the sector were determined to make recommendations for development in the secondary environmental areas with some potential. This study was also useful to set up policies, as well as general and specific guidelines. [ABSTRACT FROM AUTHOR]

The goal of this paper was to assess the behavior of chemical composition indicators (dry matter, ash, gross protein, phosphorous, and potassium) of two new sugar cane varieties, based on plant fractions and re-shoot age. Chemical analyses were made to several plant fractions (whole, nodes, stem) at different re-shoot ages (six, eight, and eleven months). Forage variety My5514 was used as control. Multifactorial variance analyses were also made. The results demonstrated that the chemical composition indicators of ash, gross protein, phosphorous, and potassium in sugar cane, depended on the age of re-shoot, variety, and plant fraction. Dry matter also depended on the re-shoot age and plant fraction. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to make a contribution to the environmental arrangement of the livestock potential in the municipality of Jimaguayú, Camagüey, Cuba. The indicators restrictions, categories, and conflicts of the livestock potential in the region were identified and located on a map. Additionally, the policies, guidelines, regulations and standards for proper environmental management in each livestock area were determined. The study concluded that the potential of livestock activity consists in environmentally recommended use in the main eight of the seventeen secondary environmental areas that make up the region. One of them was considered for secondary use. In terms of categories, the municipality comprises 126.9 km2 with inexistent livestock potential, including several settlements and water reservoirs; 115.7 km2 were identified as poor potential; 316.3 km2 had a mid-potential; and 225.4 km2 was high. The previous contributed to the environmental arrangement of the livestock potential in the municipality of Jimaguayú, Camagüey. Accordingly, the restrictions, indicators, categories, and conflicts observed in the sector were determined, to be used as recommendations for development in the secondary environmental areas with some potential, as well as to set up policies, and general and specific guidelines. [ABSTRACT FROM AUTHOR]

The aim of this paper was to determine the size of the pre-ovulation follicle in the corpus luteum, and in blood progesterone on the sixth and twelfth days after ovulation, in Holstein, Brown, Swiss and Criolla breeds grazing on Ecuadoran Highlands. The size of the pre ovulation follicle and corpus luteum, and the levels of blood progesterone were determined on days sixth and twelfth, in nine heifers from each breed. Assessment of ovarian structures was made by ultrasound scanning. The concentration of blood progesterone was determined by electrochemiluminescence. The pre ovulation follicle in Criolla heifers was larger (14.6 ± 0.41 mm) than in Holstein (12.7 ±0.47 mm), and in Brown Swiss (12.7 ± 0.65 mm). Progesterone concentration on days six and twelve after ovulation of Criolla heifers (11.0 ± 1.68 ng/ml, and 18.4 ± 2.04 ng/ml, respectively) was higher than for Holstein and Brown Swiss. The linear association values were high and significant (P < 0.05), in the pre ovulation follicle, corpus luteum and progesterone, in Holstein and Brown Swiss. It was demonstrated that for every additional millimeter above the Criolla mean on the sixth day, 1.67 ng/ml more of progesterone was generated in Criolla heifers (P < 0.05) than in the rest. It was concluded that the Criolla heifers had higher progesterone levels than Holstein and Brown Swiss on the sixth and twelfth days, thus producing better conditions in the uterus and lower early embryo losses. [ABSTRACT FROM AUTHOR]

The aims of this paper were to classify cattle farms by Multivariate statistics, and to characterize the groups of cattle farms of two parishes in Chunchi canton, Chimborazo province, Ecuador, for rural extension work. The factors achieved in the reduction of dimensions (8) were used to make hierarchical clustering analysis based on the Ward's method, with an Euclidean distance cut of 15. Four groups were made and named after the appearance frequency. The groups were characterized by means of central tendency and frequency distribution. Group 4 was superior in terms of surface area, but all the farms studied may be regarded as small, according to the classification of the National Institute of Statistics and Census (INEC). Number of trees was lower in group 2, suggesting interest in intensification based on space. Group 4 had more cows, thus recurring to concentrated feeds more often. Group 1 reported the need for more training. It was concluded that groups 1 and 3 required greater support from the rural extension system; group 4 showed traits of numerical superiority of the variables. Accordingly, an efficiency study of the groups identified is suggested. [ABSTRACT FROM AUTHOR]

The aim of this paper is to assess economic and biologic feasibility of different feed categories in swine prefattening and fattening. Equally important is to quantify the contribution of nutrients, digestible energy, and raw proteins based on conventional raw materials (corn and soybean), as well as non-conventional ones (parted rice, fat and sun flower meal). A composition analysis was made, and rations for pigs were simulated in the above-mentioned stages. According to the standard supplies, the protein levels found in the single-type feed were either excessive or deficient at times, in relation to the animal requirements. The costs of production were subsequently increased, and nutritional unbalances were observed, making feed rations costlier than the feeds made for the stages under the study, using non-conventional raw materials. [ABSTRACT FROM AUTHOR]

Cupric sulfate has been used as growth promoter in swine productions for a long time instead of the ecological risks involved. The paper had the objective of evaluating the effect of cooper as inductor of antibiotic-resistance in enterotoxigenic Escherichia coli. The reference strains A-1 (O149: K91: K88ac) and E68-I (O141: K85: K88ab) were cultivated on Mueller-Hinton Agar plates following the gradient concentration technique with ranges increased weekly from 5 till 50 mg/mL of CuSO4. Both bacteria were streaked during three weeks in parallel to controls cultured in pure medium without the inductor. At the end of the experiment the sensibility of bought groups to Gentamicin, Kanamycin, Tetracycline, Chloramphenicol, Carbenicilin and Nalidix Acid was measured. The variants treated with cooper exhibited halos referred as resistant to the antibiotics evaluated instead all the controls were sensitive. The results demonstrated the capability of cooper to develop bacterial antibiotic-resistance in vitro, another trait to be considered by producers when salts of this metal are used as growth promoters, because together with its ecological damage a lose in the effectiveness of antimicrobials employed in human and veterinary chemotherapy is developed. [ABSTRACT FROM AUTHOR]

Cupric sulfate has been used as growth promoter in swine productions for a long time instead of the ecological risks involved. The aim of this paper was evaluating the in vitro behavior of enterotoxigenic Escherichia coli to increasing concentrations of copper. Six strains and two of references were used A-1 (O149: K91: K88ac) and E68-I (O141: K85: K88ab), and four isolated from calves with colibacilosis. This strain were cultivated on Mueller-Hinton Agar plates following the gradient concentration technique with ranges increased weekly from 5 till 50 mg/mL of CuSO4. The experiment lasted three weeks. All strains developed a high metal tolerance, although there was a better fit in the initial contacts in two of the wild strains. Tolerance in A-1 case may be determined by biofilm formation; this phenomenon is an important virulence factor in bacterial infectious processes and it's another trait to be considered by producers when salts of this metal are used as growth promoters. [ABSTRACT FROM AUTHOR]