Contamination of cattle carcasses by Escherichia coli shiga like toxin with high antimicrobials resistence

During processing of cattle carcasses, contamination may occurs with the transfer of microbiota of animals feaces to carcasses. This contamination many times may be by Escherichia coli carriers of virulence factor as stx and eae genes being classified as Shiga like toxin. Shiga toxin-producing Escherichia coli (STEC) is recognized wordwide as human pathogen. A survey was performed to determine the sensibility profile to several antimicrobial drugs of STEC in carcasses obtained from an abattoir in Brazil between March 2008 and August at 2009. A total of 120 STEC were isolated. All isolates were confirmed as being E. coli by their biochemical analysis and submitted to polymerase chain reaction (PCR) for detection of stx, eae and ehly genes. No strains was isolated being carriers of ehly gene. The number of isolates carriers of eae gene were 48/120. The most frequent resistance was seen against cephalothin (84.0%), streptomycin (45.0%), nalidixic acid (42.0%) and tetracycline (20.0%). Multidrug resistance (MDR) to three or more antimicrobial agents was observed in 46 (38.3%) E. coli isolates. The findings of STEC and MRD show that cattle carcasses may be a reservoir of pathogenic bacterial for the consumer public. © 2011 Academic Journals.

Digestibilidade e Parâmetros Ruminais de Bovinos Consumindo Brachiaria Brizantha Cv. Marandu

This experiment aimed to evaluate nutrient intake, total and partial digestibility of dry matter (DM), organic matter (OM), crude protein (CP), neutral (NDF) and acid (ADF) detergent fiber and ruminal parameters, ammonia concentration and volatile fatty acids, in beef cattle fed palisade grass (Brachiaria brizantha cv. marandu) at two regrowth ages, 30 and 60 days, at two times of year (January and February). The intake of DM, OM and CP was influenced by forage age of regrowth with high values for 30 days; this was influenced by time of year, being observed in February the higher intake by animals. DM digestibility average was 60.7 and 59.4% for 30 and 60 days of forage regrowth, respectively, however, was observed effect of interaction between regrowth and time of year, the same comportment was observed for OM, averages were 63.9 and 63% for respective ages of regrowth. CP digestibility was higher for 30 days, 70.8%, than for 60 days of regrowth, 57%. The NDF and ADF digestibilities were influenced by the interaction between regrowth and time of year; their average for 60 days of regrowth in January were respectively 54.8 and 48.5%, being the lower values and, in February, the higher values: 64.9 and 60.4%. The ruminal average digestibility was 79.5, 86.2, 99.4 and 96.7% of the total degradable for DM, OM, NDF and ADF, respectively. Effects of regrowth and time of year there were not recorded. Two hours after the morning meal was observed the ammonia ruminal concentration peak. The acetate:propionate: butirate ruminal ratio observed was 74:18:8(%).

Use of bayesian inference to correlate in vitro embryo production and in vivo fertility in Zebu Bulls

The objective of this experiment was to test in vitro embryo production (IVP) as a tool to estimate fertility performance in zebu bulls using Bayesian inference statistics. Oocytes were matured and fertilized in vitro using sperm cells from three different Zebu bulls (V, T, and G). The three bulls presented similar results with regard to pronuclear formation and blastocyst formation rates. However, the cleavage rates were different between bulls. The estimated conception rates based on combined data of cleavage and blastocyst formation were very similar to the true conception rates observed for the same bulls after a fixed-time artificial insemination program. Moreover, even when we used cleavage rate data only or blastocyst formation data only, the estimated conception rates were still close to the true conception rates. We conclude that Bayesian inference is an effective statistical procedure to estimate in vivo bull fertility using data from IVP. © 2011 Mateus José Sudano et al.

Chromatin modifying agents in the in vitro production of bovine embryos

The low efficiency observed in cloning by nuclear transfer is related to an aberrant gene expression following errors in epigenetic reprogramming. Recent studies have focused on further understanding of the modifications that take place in the chromatin of embryos during the preimplantation period, through the use of chromatin modifying agents. The goal of these studies is to identify the factors involved in nuclear reprogramming and to adjust in vitro manipulations in order to better mimic in vivo conditions. Therefore, proper knowledge of epigenetic reprogramming is necessary to prevent possible epigenetic errors and to improve efficiency and the use of in vitro fertilization and cloning technologies in cattle and other species. Copyright © 2011 Fabio Morato Monteiro et al.

Treatments to optimize the use of artificial insemination and reproductive efficiency in beef cattle under tropical environments

Bos indicus cattle, the preferred genetic group in tropical climates, are characterized by having a lower reproductive efficiency than Bos taurus. The reasons for the poorer reproductive efficiency of the Bos indicus cows include longer lengths of gestation and postpartum anestrus, a short length of estrous behavior with a high incidence of estrus occurring during the dark hours, and puberty at older age and at a higher percentage of body weight relative to mature body weight. Moreover, geography, environment, economics, and social traditions are factors contributing for a lower use of reproductive biotechnologies in tropical environments. Hormonal protocols have been developed to resolve some of the reproductive challenges of the Bos indicus cattle and allow artificial insemination, which is the main strategy to hasten genetic improvement in commercial beef ranches. Most of these treatments use exogenous sources of progesterone associated with strategies to improve the final maturation of the dominant follicle, such as temporary weaning and exogenous gonadotropins. These treatments have caused large impacts on reproductive performance of beef cattle reared under tropical areas. Copyright © 2011 O. G. Sá Filho and J. L. M. Vasconcelos.

Indicadores na estimativa do fluxo de digesta em bovinos de corte

single and double marker methods were compared in seven Nellore steers with average body weight 250 kg, and previously canullated in the rumen and duodenum. The animals were fitted with continuous-infusion pump that administered CoEDTA solutions intraruminally. In addition, a capsule containing Cr 2O 3, and other, containing external n-alkanes C 32, C 36 were inserted into the rumen of each steer. Internal markers indigestible neutral-detergent fiber and acid-detergent fiber (iNDF and iADF after 144 h in situ incubation) and internal n-alkanes C 31, C 33, C 35 were components of the diet. Steers were fed with palisade grass (Brachiaria brizantha cv. marandu) in two age of regrowth, 30 and 60 days. The duodenal flow experimental design was a factorial 2×2×12 while omasal experimental design was a factorial 2×2×4. Markers iNDF, CoEDTA and the combination Co+iNDF were efficacious to estimate duodenal dry matter flow whereas iNDF, iADF and the Co+iADF combination were all efficacious to predict omasal dry matter flow. In conclusion, the double marker method for estimation of omasal and duodenal dry matter flow was the most appropriate considering the ruminal fiber digestibility.

How FTAI and FTET impact reproductive efficiency of Brazilian dairy herds

Background: Throughout dairy cows evolution, milk production was always the key point to select the superior animal. Currently, several evidences has shown that high milk production have intensively contributed to the decline of dairy cattle fertility. Beyond milk production, dairy cows have their reproductive performance impaired by another factors, heat stress and repeat-breeding. Methods like fixed time artificial insemination and embryo transfer were developed to minimize the effects of these factors, and improve dairy herds profitability. This review aims to show some key-point experiments conducted to improve the efficiency of the self-appointed protocols for artificial insemination and embryo transfer in Brazil, overcoming several reproductive problems. Our goal is to develop cheap and easy self-appointed programs that facilitate animal handling and maximize their reproductive outcomes all over the year. Review: Failure in estrus detection is the mainly limiting factor for the use of artificial insemination in high-production dairy herd. An excellent alternative to overcome the need of estrus detection is fixed time artificial insemination. Many protocols with and without the use of estradiol have been developed to that end. Among the protocols for fixed time artificial insemination without estradiol, DoubleOvsynch has been extensively used recently in American dairy herds. In Brazil, similar pregnancy rate was obtained compared to progesterone-estradiol based protocols for fixed time artificial insemination. Particularities of progesterone-estradiol based protocols as (1) new progesterone device or devices previously used for eight days; (2) different doses of eCG; and (3) the use of estradiol cypionate for fixed time artificial insemination have been studied in Brazil. The use of self-appointed artificial insemination also enabled the reduction of the interval calving-conception compared to cows inseminated following the standing estrus. Regarding the low fertility of repeat breeders and the effect of heat stress at early pregnancy, other methods like embryo transfer became important tools to enhance reproductive efficiency of Brazilian dairy herds. Protocols were also developed to allow fixed time embryo transfer, eliminating the need of estrus detection and improving the reproductive efficiency of lactating recipients. As well as described for fixed time artificial insemination treatments, there is a large variety of hormone combination for fixed time embryo transfer (with and without estradiol). An experiment conducted in Brazil demonstrated that protocols for fixed time embryo transfer without estradiol can be as good as with estradiol to synchronize high-producing Holstein recipients, essentially during summer. Particularities related to embryos cryopreservation, synchronization of the estrus cycle of donors and recipients and the site of embryo release into the uterine horn were also investigated. Greater conception rates were achieved when fresh embryos were transferred compared to frozen-thawed ones. Also, the tight synchronization between donor and recipient (same day of estrus) resulted more pregnancies than when recipients were one day later or in advantage in relation to donors. Moreover, the site of embryo release into the uterine horn (ipsilateral to the corpus luteum) had no effect on pregnancy rates after in vivo produced embryo transfer. Conclusion: Both fixed time artificial insemination and fixed time embryo transfer are important tools to improve reproductive efficiency of high-producing dairy cows. These biotechnologies help bypassing some of the greatest challenges of dairy cattle reproduction: the difficulties of estrus detection, and the low fertility associated to heat stress and repeat breeding.

Implementation of DNA markers to produce genomically - Enhanced EPDs in nellore cattle

Background: The sequencing and publication of the cattle genome and the identification of single nucleotide polymorphism (SNP) molecular markers have provided new tools for animal genetic evaluation and genomic-enhanced selection. These new tools aim to increase the accuracy and scope of selection while decreasing generation interval. The objective of this study was to evaluate the enhancement of accuracy caused by the use of genomic information (Clarifide® - Pfizer) on genetic evaluation of Brazilian Nellore cattle. Review: The application of genome-wide association studies (GWAS) is recognized as one of the most practical approaches to modern genetic improvement. Genomic selection is perhaps most suited to the improvement of traits with low heritability in zebu cattle. The primary interest in livestock genomics has been to estimate the effects of all the markers on the chip, conduct cross-validation to determine accuracy, and apply the resulting information in GWAS either alone [9] or in combination with bull test and pedigree-based genetic evaluation data. The cost of SNP50K genotyping however limits the commercial application of GWAS based on all the SNPs on the chip. However, reasonable predictability and accuracy can be achieved in GWAS by using an assay that contains an optimally selected predictive subset of markers, as opposed to all the SNPs on the chip. The best way to integrate genomic information into genetic improvement programs is to have it included in traditional genetic evaluations. This approach combines traditional expected progeny differences based on phenotype and pedigree with the genomic breeding values based on the markers. Including the different sources of information into a multiple trait genetic evaluation model, for within breed dairy cattle selection, is working with excellent results. However, given the wide genetic diversity of zebu breeds, the high-density panel used for genomic selection in dairy cattle (Ilumina Bovine SNP50 array) appears insufficient for across-breed genomic predictions and selection in beef cattle. Today there is only one breed-specific targeted SNP panel and genomic predictions developed using animals across the entire population of the Nellore breed (www.pfizersaudeanimal.com), which enables genomically - enhanced selection. Genomic profiles are a way to enhance our current selection tools to achieve more accurate predictions for younger animals. Material and Methods: We analyzed the age at first calving (AFC), accumulated productivity (ACP), stayability (STAY) and heifer pregnancy at 30 months (HP30) in Nellore cattle fitting two different animal models; 1) a traditional single trait model, and 2) a two-trait model where the genomic breeding value or molecular value prediction (MVP) was included as a correlated trait. All mixed model analyses were performed using the statistical software ASREML 3.0. Results: Genetic correlation estimates between AFC, ACP, STAY, HP30 and respective MVPs ranged from 0.29 to 0.46. Results also showed an increase of 56%, 36%, 62% and 19% in estimated accuracy of AFC, ACP, STAY and HP30 when MVP information was included in the animal model. Conclusion: Depending upon the trait, integration of MVP information into genetic evaluation resulted in increased accuracy of 19% to 62% as compared to accuracy from traditional genetic evaluation. GE-EPD will be an effective tool to enable faster genetic improvement through more dependable selection of young animals.

Correlações entre características morfogênicas e estruturais em pastos de capim-braquiária

The analysis of both morphogenetic and structural characteristics of pasture allows us to understand the response patterns of the plant to the environment. Thus, this study was conducted to evaluate the associations between the morphogenetic and structural characteristics of Brachiaria decumbens under continuous grazing by cattle. The development of individual tillers in pastures was evaluated under two grazing management strategies during three seasons (winter, spring and summer). Pearson correlations between variables were estimated. The lengths of leaf and stem, number of tillers and leaves per tiller, rates of leaf appearance and elongation of leaf and stem of B. decumbens were positively correlated. There was a negative relationship between appearance and lifespan of leaves (r = -0.89). However, positive correlations between leaf appearance rate and number of tillers (r = 0.64) and between length of stem and leaf senescence rate (r = 0.63) were determined. The B. decumbens modifies its morphogenesis to better adapt to climate and grazing management.

Acidosis ruminal en bovinos lecheros: Implicaciones sobre la producción y la salud animal

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Use of cooled bull semen as a strategy to increase the pregnancy rate in fixed-time artificial insemination programs-case report

Semen cryopreservation is still considered suboptimal due to lower fertility when compared to fresh semen. The reasons for the loss of fertility are various and related to irreversible damage caused to the cells during the freeze-thaw process. An alternative to conventional cryopreservation represents the use of chilled bull semen, preventing the damage associated with freezing, thereby guaranteeing greater sperm viability. The aim of this study was to describe the use of cooled bull semen as a strategy to increase the pregnancy for Fixed-Time Artificial Insemination (FTAI) of Nellore (Bos indicus) cows. One ejaculate of a select Nellore bull obtained by electroejaculation was used; the semen sample was fractioned into two aliquots: one diluted in Botu-Bov® extender containing 6.4% glycerol for cryopreservation (BB-F, frozen group) and one diluted in the same extender, free from cryoprotectants and used for cooling (BB-C, cooled semen group). The samples in the BB-C group were chilled to 5°C using an isothermic box and maintained for 24 h prior to use. A total of 349 lactating Nellore cows (70-90 days after birth) were synchronized by the insertion of a progesterone releasing device (1.0 g) and estradiol benzoate (2.0 mg i.m.) on a random day of the estrous cycle (Day 0); FTAI was performed 44-48 h after the removal of the device. The pregnancy rates were 45.71 and 61.49% (P<0.05), respectively, for the cryopreserved or chilled bovine semen groups. In conclusion, the use of bull semen cooled for 24 h represents an alternative to conventionally cryopreserved semen, as determined by the increase the pregnancy per artificial insemination in bovine herds. © 2012 Science Publication.

Mastigação simulada e digestão ácido-enzimática de sementes de leguminosas forrageiras tropicais

This study aimed to evaluate the effect of simulated chewing in the laboratory on the survival of seeds of four tropical forage legumes (butterfly pea, Clitorea ternatea; estilosantes, Stylosanthes capitata/S. macrocephala 'Campo Grande; archer, Macrotyloma axillare and perennial soybean, Neonotonia wightii) submitted to different periods of acid enzymatic digestion in vitro. Three trials were conducted to observe the percentage of destroyed seeds by the mastication; to compare the germination of the seeds (intact seeds, simulated mastication, scarification with sandpaper, mastication and scarification with sandpaper). And, finally the seeds were incubated at 39oC with hydrochloric acid and pepsin for: 0, 2, 4, 8, 12 and 24 hours. The percentages of not destroyed seeds in mastication (archer, 91,5; perennial soybean, 88.0; butterfly pea, 82.1, and estilo, 81.1), associated with the beneficial effects of scarification on germination (64.7, 60.0, 92.0 e 87.3%, respectively) and the effects of time of acid-enzymatic digestion (75% higher if they stay 24 hours in HCl + pepsin) associated to the hard and not permeable coats of legume seeds, allow a high potential for resistance, and to pass intact through the digestive tract of cattle, being able to germinate when defecated in the pastures. However, estilo should not be included in the feeding of cattle for this purpose, because it do not resists the acid-enzyme digestion.

How bioinformatics enables livestock applied sciences in the genomic era

This review paper presents the three main approaches currently used in livestock genomic sciences where the bioinfomatics plays a critical role. They are named as Genomic Selection (GS), Genome Wide Association Study (GWAS) and Signatures of Selection (SS). The subsides for the construction of this article were generated in a current project (started in 2011), so called Zebu Genome Consortium (ZGC), which joins researchers from different institutions and countries, aiming to scientifically explore genomic information of Bos taurus indicus cattle breeds and deliver useful information to breeders and academic community, specially from the tropical regions of the world. © 2012 Springer-Verlag.

Infecção pelo vírus da diarreia viral bovina em vacas gestantes abatidas no Estado de São Paulo-Brasil

The most important pathogens in the bovine livestock nowadays in the virus of the viral diarrhea mainly for triggered clinical manifestations related to the reproductive sphere. The infection in pregnant females, may result in abortions, embryonic resorptions, fetal mummification, birth of weak and malformation of the cattle. Moreover, their birth with persistently infected and immunotolerant virus, which the source of infection and dissemination of their disease. Nowadays, the complexity of the diagnosis and consequently its pathogenesis are tilted in the genotypic differences agent. So, this study aimed to verify the occurrence of the BVDV-1 (SINGER) and BVDV-2 (VS-253) genotypes in cows and their respective fetuses, slaughtered in an abattoir in the State of Sao Paulo. Through blood serum, using virus neutralization technique. All in all, 52,51% (115/219) of the cows which were tested reacted, but no fetus (0/219) reacted, to its virus neutralization. Through this cross-examination we observed that 42% (92/219) of cows reacted for both BVDV-1 and BVDV-2. Furthermore 4,10% (9/219) of them reacted only to the genotype BVDV-1 and 6,39% (14/219) responded only to the genotype 2 of BVDV. Therefore it was noticed that both strains are widespread in the regions studied, which justifies the use of different antigens to avoid false-negative diagnosis. Finally antibodies showed no fetus or fetal abnormalities, it is already developed and can be considered immunocompetent, independent child born to a reagent.

Extrato de própolis no controle de helmintoses em bezerros

The use of conventional anthelmintic has been a growing concern among consumers who have become more and stricter toward drug residues in products of animal origin. Thus, this research aimed to evaluate the anthelmintic effect of alcoholic extract of propolis, at 30% of concentration, in naturally infected calves. Twelve calves weighting 60 kg and aging 90 days old were used. The treatments were performed by direct oral administration of 10 mL of EAP. The calves received the extract at every 8 h intervals, for five consecutive days. The results were evaluated comprising the detection of light and heavy eggs counted per gram of feces (EPG), immediately before and after treatment, calculating the percentage of reduction. For the statistical analysis, the results were evaluated by Wilcoxon unilateral test of signed points at 5% probability. Trichostrongylus sp. and Strongyloides sp. were found. After treatment, 83% of animals showed an average decrease of 48.48% per counting of EPG. Therefore, propolis may represent an important adjunctive therapy to control helminthiasis in cattle. It was particularly important in ecological organic and biological-dynamic systems of production, whose use of chemicals is prohibitive and limiting factor for certification.