Genetic parameters for traditional and novel ultrasound carcass traits in Nellore cattle.

The objective of this study was to contribute to genetic improvement for carcass quality in Nellore cattle by estimating genetic parameters for carcass characteristics measured by traditional and novel ultrasound adjusted for body weight. Records of 19,910 Nellore breed animals born between 2001 and 2015 as part of a genetic improvement program were evaluated for this purpose. The (co)variance components and genetic parameters for yearling weight (YW), slaughter conformation at yearling age (SCY), ribeye area (REA), REA adjusted for 100 kg of body weight (REA100), REA adjusted for 450 kg of body weight (REA450), subcutaneous fat thickness over the loin (SFTL) and the rump (SFTR), intramuscular fat (IF), and height × width ratio of the sirloin steak (RATIO) were estimated using the restricted maximum likelihood (REML) method and the three-trait animal model. The estimated heritability values were 0.39 (YW), 0.33 (SCY), 0.31 (REA), 0.42 (REA100), 0.38 (REA450), 0.31 (RATIO), 0.17 (SFTL), 0.27 (SFTR), and 0.41 (MAR). The genetic correlations between REA and YW (0.43) and SCY and YW (0.78), respectively, suggested that selecting for REA or SCY could result in an increase in body weight. Because of its moderate and negative correlation with YW, REA100 was ineffective as a muscling indicator (- 0.38). The indicators REA450 and RATIO had a - 0.12 and 0.11 low correlation with YW, respectively. Thus, it is concluded that REA450 and RATIO were the best indicators of muscling, with heritability of medium magnitude, making the selection viable, as well as having a low correlation with body weight.

Activation of C-C motif chemokine receptor 2 modulates testicular macrophages number, steroidogenesis, and spermatogenesis progression.

The monocyte chemoattractant protein 1 (MCP-1) belongs to the CC chemokine family and acts in the recruitment of C-C motif chemokine receptor 2 (CCR2)-positive immune cell types to inflammation sites. In testis, the MCP-1/CCR2 axis has been associated with the macrophage population's functional regulation, which presents significant functions supporting germ cell development. In this context, herein, we aimed to investigate the role of the chemokine receptor CCR2 in mice testicular environment and its impact on male sperm production. Using adult transgenic mice strain that had the CCR2 gene replaced by a red fluorescent protein gene, we showed a stage-dependent expression of CCR2 in type B spermatogonia and early primary spermatocytes. Several parameters related to sperm production were reduced in the absence of CCR2 protein, such as Sertoli cell efficiency, meiotic index, and overall yield of spermatogenesis. Daily sperm production decreased by almost 40%, and several damages in the seminiferous tubules were observed. Significant reduction in the expression of important genes related to the Sertoli cell function (Cnx43, Vim, Ocln, Spna2) and meiosis initiation (Stra8, Pcna, Prdm9, Msh5) occurred in comparison to controls. Also, the number of macrophages significantly decreased in the absence of CCR2 protein, along with a disturbance in Leydig cell steroidogenic activity. In summary, our results show that the non-activation of the MCP-1/CCR2 axis disturbs the testicular homeostasis, interfering in macrophage population, meiosis initiation, blood-testis barrier function, and androgen synthesis, leading to the malfunction of seminiferous tubules, decreased testosterone levels, defective sperm production, and lower fertility index.

Burden of early, advanced and metastatic breast cancer in The Netherlands.

BACKGROUND: The aim of this study was to estimate the total economic and health related burden of breast cancer in the Netherlands. METHODS: Data on incidence, prevalence, mortality and survival were extracted from the Dutch National Cancer Registry and were used to calculate the economic and health related burden of breast cancer for overall, DCIS (stage 0), early- (stage I), locally advanced- (stage II-III) and metastatic- (stage IV) breast cancer by age groups and by year (if applicable). RESULTS: The overall incidence of breast cancer increased from 103.4 up to 153.2 per 100,000 women between 1990 and 2014. The increase was driven by DCIS and early breast cancer as the incidence of locally advanced and metastatic breast cancer remained stable. Between 1990 and 2014, ten-year overall survival rates increased from 87% to 93% for early breast cancer, 41% to 62% for locally advanced- and from 6% to 9% for metastatic disease. Annually, breast cancer in the Netherlands is responsible for approximately 3100 deaths, 26,000 life years lost, 65,000 Disability Adjusted Life Years (DALYs) and an economic burden of €1.27 billion. CONCLUSIONS: This study provides a comprehensive assessment of the burden of breast cancer and subsequent trends over time in the Netherlands.

Prenatal depression, fetal neurobehavior, and infant temperament: Novel insights on early neurodevelopment from a socioeconomically disadvantaged Indian cohort.

This article extends the research focusing on the early origins of psychopathology into the prenatal period, by exploring the association between maternal prenatal depression and offspring (fetal and infant) neurobehavior. The sample is recruited from a rural population in South India where women in the third trimester of pregnancy were assessed for depression and the heart rate responses of their fetuses to extrinsically applied vibroacoustic stimuli were studied. At 2 months postbirth, infant temperament and cortisol responsivity to immunization were assessed. The association between maternal prenatal depression and fetal responsivity to vibroacoustic stimulation, and infant responsivity to immunization, was U shaped with higher levels of responsivity noted in the offspring of mothers with very high and very low depression scores, and lower levels noted in the offspring of mothers with moderate depression scores. Maternal prenatal depression was not associated with infant temperament. The findings highlight the importance of environmental influences in the developmental origins of neurobehavior, suggesting that such differences, not evident at baseline, may emerge upon exposure to stressors. The study also emphasizes the need for further investigation in low- and middle-income contexts by providing preliminary evidence of the differing patterns of association observed between high- and low-income populations.

Biofilm formation on different pH conditions by Streptococcus agalactiae isolated from bovine mastitic milk.

Streptococcus agalactiae is among the most relevant aetiologic agent of bovine clinical and subclinical mastitis, a major problem for the dairy industry. In Brazil, clonal diversity, capsular typing and multidrug resistance profiles of S. agalactiae related to human and bovine infections need further investigation. Presently, S. agalactiae isolates of bovine subclinical mastitis, from Brazilian Northeastern region, were submitted to capsular and pulsed-field gel electrophoresis (PFGE)-typing, antimicrobial susceptibility and assays of biofilm formation at different time incubation and pH levels. Sixteen bovine isolates were characterized by polymerase chain reaction assay as S. agalactiae capsular type II (CTII) and classified by PFGE in A1/A2 (n = 06), B1/B2 (n = 06), C (n = 03) and D (n = 01) patterns. Bovine S. agalactiae CTII strains were classified as 25% multidrug-resistant (MDR) with susceptibility to penicillin, linezolid and vancomycin. Biofilm formation on abiotic surface was strain- and time-dependent with significantly higher rates at pH 6·5. In conclusion, S. agalactiae capsular type II isolates recovered from bovine subclinical mastitis produced different pH-dependent biofilm levels. Our findings suggest that biofilm production is modulated by environmental factors and provides S. agalactiae advantageous in colonizing mammary gland during mastitis development, including MDR strains. SIGNIFICANCE AND IMPACT OF THE STUDY: Streptococcus agalactiae is among the most relevant aetiologic agent of bovine clinical and subclinical mastitis, a major problem for the dairy industry. The disease may cause significant economic loss due to decreased production and milk quality and increased use of medicaments. Presently, data demonstrated that biofilm formation favours the establishment of infectious process in health mammary tissue by S. agalactiae and emphasizes that an acidic pH promotes adhesion by biofilm-forming bacterial strains. S. agalactiae strains (25%) showed resistance to tetracycline, azithromycin, erythromycin and clindamycin, and consequently were classified as multidrug-resistant strains.

Insights into the genetic structure of the rabbitfish Chimaera monstrosa (Holocephali) across the Atlantic-Mediterranean transition zone.

A comparison of the genetic structure of Chimaera monstrosa populations from the Atlantic Ocean and the Mediterranean Sea was carried out using mitochondrial DNA analysis. Results indicate high and significant pairwise ΦST values with no shared haplotypes between the two areas. Furthermore, migration rate estimates suggested absence of gene flow between the two basins. These findings, coupled with the species vertical distribution, suggest that the shallow depth of the Strait of Gibraltar may act as a barrier limiting the dispersal capabilities of these populations, which likely became separated at the end of the middle Pleistocene.

Meta-analysis of the concordance of histological grade of breast cancer between core needle biopsy and surgical excision specimen.

BACKGROUND: With the increasing use of neoadjuvant chemotherapy and minimally invasive ablative therapy in breast cancer, pretreatment assessment of tumour grade on core needle biopsy (CNB) is increasingly needed. However, grading on CNB is possibly less accurate than grading based on the surgical excision specimen. A systematic review and meta-analysis of the literature was conducted to derive a reliable estimate of the agreement in tumour grading between CNB and subsequent surgical excision. METHODS: Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) criteria, Embase, PubMed and the Cochrane Library were searched. Pooled proportions of agreement in grading between CNB and the excision specimen, Cohen's κ and percentages of overestimation and underestimation were calculated. Random-effects models were applied because of substantial heterogeneity, assessed by I2 test. Determinants of the level of agreement in grading were explored with meta-regression. RESULTS: Thirty-four articles were included in the systematic review (6029 patients) and 33 in the meta-analysis (4980 patients). Pooled agreement and κ were 71·1 (95 per cent c.i. 68·8 to 73·3) per cent and 0·54 (0·50 to 0·58) respectively. Underestimation and overestimation occurred in 19·1 (17·1 to 21·3) and 9·3 (7·7 to 11·4) per cent respectively. Meta-regression showed associations between agreement of histological type (positive association) and proportion of patients with oestrogen receptor-positive disease (negative association) and grade agreement. CONCLUSION: Grading on CNB corresponds moderately with grading based on excision specimens, with underestimation in about one in five patients. Incorrect CNB tumour grading has limited clinical implications, as multiple factors influence decision-making for adjuvant systemic therapy.

Inbreeding depression in Zebu cattle traits.

The productivity of herds may be negatively affected by inbreeding depression, and it is important to know how intense is this effect on the livestock performance. We performed a comprehensive analysis involving five Zebu breeds reared in Brazil to estimate inbreeding depression in productive and reproductive traits. Inbreeding depression was estimated for 13 traits by including the individual inbreeding rate as a linear covariate in the standard genetic evaluation models. For all breeds and for almost all traits (no effect was observed on gestation length), the performance of the animals was compromised by an increase in inbreeding. The average inbreeding depression was -0.222% and -0.859% per 1% of inbreeding for linear regression coefficients scaled on the percentage of mean (ßm ) and standard deviation (ßσ ), respectively. The means for ßm (and ßσ ) were -0.269% (-1.202%) for weight/growth traits and -0.174% (-0.546%) for reproductive traits. Hence, inbreeding depression is more pronounced in weight/growth traits than in reproductive traits. These findings highlight the need for the management of inbreeding in the respective breeding programmes of the breeds studied here.

Foetal exposure to maternal depression predicts cortisol responses in infants: findings from rural South India.

BACKGROUND: Maternal depression during pregnancy is associated with an increased risk of adverse child outcomes. One potential mechanism is the influence of antenatal depression on the foetal hypothalamic-pituitary-adrenal axis. This can be observed as disturbances in baseline cortisol secretion during childhood. The influence of antenatal depression on infant cortisol reactivity to a stressor may provide further insight into this association. In addition, the dose-response relationship between foetal exposure to antenatal depression and infant cortisol reactivity is unclear. METHODS: A consecutive sample of 133 pregnant women in their third trimester was recruited from an antenatal clinic in Karnataka, South India. Women were assessed for depression before and after birth on the Edinburgh Postnatal Depression Scale (EPDS) and the Kessler 10 Scale. Salivary cortisol response to immunization was measured in 58 infants at 2 months of age. We aimed (i) to investigate the association between antenatal depression and infant cortisol reactivity to immunization and (ii) to explore whether the relationship is dose-dependent. RESULTS: Exposure to antenatal depression independently predicted elevated infant cortisol responses to immunization (ß = 0.53, P = 0.04). The association was found to be U-shaped, for antenatal depression measured on the EPDS, with the infants exposed to the highest and lowest levels of maternal antenatal EPDS scores during intra-uterine life showing elevated cortisol responses to immunization (R(2) = 0.20, P = 0.02). Infants exposed to moderate levels of maternal antenatal depression showed the lowest cortisol response to immunization. CONCLUSIONS: These findings suggest that the association between antenatal depression and infant cortisol reactivity is dose-dependent and U-shaped, implying that infants exposed to both low and high levels of maternal depression showed greater reactivity. The study provides the first evidence of such an association from a low-income setting.

Acute murine-betacoronavirus infection impairs testicular steroidogenesis and the quality of sperm production.

Although several testicular alterations promoted by coronavirus infection have been demonstrated, the extent, causes, and players of testicular pathogenesis are not totally understood. The present study aimed to investigate the short-term effects on male fertility of intranasally administered murine hepatitis virus strain 3 (MHV-3), a member of the genus Betacoronavirus, which causes a severe systemic acute infection. This mouse model might be used as a in vivo prototype for investigating the impact of betacoronavirus on the endocrine and exocrine testicular functions with the advantage to be performed in a biosafety level 2 condition. Herein, we performed virological, histopathological, and molecular studies regarding the testicular spermatogenesis and the spermatic quality analyses in an MHV-3-infected C57BL/6 mice. The main outcomes showed that MHV-3 infects mouse testis and induces a testicular inflammatory state, impairing the steroidogenic pathway. The infection led to several alterations in the testicular parenchyma, such as: seminiferous epithelium sloughing, retention of residual bodies, germ cell apoptosis, alterations in intercellular junction proteins, and worse spermatogenic parameters. Moreover, the levels of plasmatic testosterone as well as the quality of sperm production reduced. Therefore, the present data suggest that the viral/inflammatory impairment of the steroidogenic pathway and the consequent imbalance of androgen levels is critical in testicular pathology, disturbing the SC barrier function and the germ cell differentiation. Our study is important for comprehending the effects of beta coronavirus infections on testis function in order to develop treatments that could prevent virus-mediated male infertility.

Genetic evaluation of Alpine goats using different milk control intervals.

The objective of this study was to compare the results of genetic evaluations by using different milk control intervals to reduce the cost of milk yield controls without harming the quality of genetic evaluation of the animals. We analyzed test day milk yield data from the Goat Sector of Universidade Federal de Viçosa. After editing and checking for errors in the database, there were 20,710 records of test day milk yield for the 667 first lactations of Alpine goats, constituting the complete file, with 7-day control intervals. Information on specific weeks was excluded from the complete file to create files with data on control intervals of 15, 21, and 28 days. The RENPED program was used to recode the pedigree and data files and correct pedigree errors; the WOMBAT program was used for genetic evaluations of the 4 files. The following comparison criteria of analysis results were used: logarithm of the function of the restricted maximum likelihood, length of the analyses in seconds, Pearson and Spearman correlations, and common elimination percentage among the areas below the regression curve of the genetic values of the animals. Overall, it is recommended that a 7-day interval among milk controls should be used in breeding programs and farms with a high technical level. Intervals of 14 and 21 days can achieve satisfactory results combined with a lower data collection cost for farms with an average-to-low technical level, less effective size, and genetic variability that depend on external genetic material for genetic improvement.

Early diagnosis of typhoid fever by nested PCR for flagellin gene of Salmonella enterica serotype Typhi.

BACKGROUND & OBJECTIVES: Typhoid fever caused by Salmonella Typhi continues to be a major health problem in spite of the use of antibiotics and the development of newer antibacterial drugs. Inability to make an early laboratory diagnosis and resort to empirical therapy, often lead to increased morbidity and mortality in cases of typhoid fever. This study was aimed to optimize a nested PCR for early diagnosis of typhoid fever and using it as a diagnostic tool in culture negative cases of suspected typhoid fever. METHODS: Eighty patients with clinical diagnosis of typhoid fever and 40 controls were included in the study. The blood samples collected were subjected to culture, Widal and nested PCR targeting the flagellin gene of S. Typhi. RESULTS: The sensitivity of PCR on blood was found to be 100 per cent whereas the specificity was 76.9 per cent. The positive predictive value (PPV) of PCR was calculated to be 76.9 per cent with an accuracy of 86 per cent. None of the 40 control samples gave a positive PCR. INTERPRETATION & CONCLUSIONS: Due to its high sensitivity and specificity nested PCR can be used as a useful tool to diagnose clinically suspected, culture negative cases of typhoid fever.

Annotated list of demersal fishes occurring at Sedlo Seamount, Azores north-east central Atlantic Ocean.

Several fish surveys were carried out in recent years at Sedlo Seamount, Azores, north-eastern central Atlantic Ocean. An objective of the surveys was to determine the species composition of the demersal fish species living in the area. Four types of sampling gears (bottom trawl and three types of longline) were used at Sedlo Seamount resulting in very different species composition by gear and a very complete coverage of the fish fauna of the area. A list of fishes caught with these sampling methods is presented, along with other specific auxiliary information. Altogether 78 species from 43 families were listed for Sedlo Seamount, and as far as is known, 15 species were recorded for the first time for Azorean waters.

Genetic and environmental factors that influence production and quality of milk of Alpine and Saanen goats.

Data from 1279 lactations of 783 Alpine and Saanen goats of the herd of our university in Minas Gerais, Brazil, were used to study environmental effects on and to estimate genetic parameters for milk production until 270 days of lactation (MP270) and for production and percentages of fat (PFAT and %FAT), protein (PPROT and %PROT), lactose (PLACT and %LACT), and total dry extract (PEXTR and %EXTR). Environmental effects were estimated by a statistical model that included contemporary group effect, type of kidding, genetic grouping, and kidding order. A multi-trait animal model with animal and permanent environment random effects was used to estimate genetic parameters and the significant environmental effects (fixed). Contemporary group influenced all traits; genetic grouping did not influence %LACT; type of kidding did not influence PFAT, %PROT or %LACT, and kidding order did not influence %FAT or %EXTR. Heritability and repeatability estimates were, respectively, 0.19 and 0.37 (MP270); 0.10 and 0.20 (PFAT); 0.12 and 0.24 (PPROT); 0.15 and 0.27 (PLACT); 0.13 and 0.24 (PEXTR); 0.21 and 0.34 (%FAT); 0.39 and 0.44 (%PROT); 0.17 and 0.29 (%LACT); 0.31 and 0.47 (%EXTR). Estimates of genetic correlations among MP270 and production of milk constituents were positive and high, but correlations between MP270 and %FAT, MP270 and %PROT, MP270 and %ESTR were moderate and negative. These heritability estimates show that satisfactory genetic gains can be obtained by selection, especially for milk constituents.

Genetic parameters for performance, feed efficiency, and carcass traits in Senepol heifers.

Improving feed efficiency is a key breeding goal in the beef cattle industry. In this study, we estimated the genetic parameters for feed efficiency and carcass traits in Senepol cattle raised in tropical regions. Various indicators of feed efficiency [gain to feed ratio (G:F), feed conversion ratio (FCR), residual weight gain (RG), residual intake and body weight gain (RIG), and residual feed intake (RFI)] as well as growth [final BW, average daily gain (ADG), and DM intake (DMI)], and carcass [rib-eye area (REA), backfat thickness (BF), intramuscular fat score, and carcass conformation score] traits were included in the study. After data editing, records from 1 393 heifers obtained between 2009 and 2018 were used for the analyses. We fitted an animal model that included contemporary group (animals from the same farm that were evaluated in the same test season) as the fixed effect, and a linear effect of animal age at the beginning of the test as a covariate; in addition to random direct additive genetic and residual effects. The (co)variance components were estimated by Bayesian inference in uni- and bivariate analyses. Our results showed that feed efficiency indicators derived from residual variables such as RG, RIG, and RFI can be improved through genetic selection (h2 = 0.14 ± 0.06, 0.13 ± 0.06, and 0.20 ± 0.08, respectively). Variables calculated as ratios such as G:F and FCR were more influenced by environmental factors (h2 = 0.08 ± 0.05 and 0.09 ± 0.05), and were, therefore, less suitable for use in breeding programs. The traits with the greatest and impact on genetic progress in feed efficiency were ADG, REA, and BF. The traits with the greatest and least impact on growth and carcass traits were RG and RFI, respectively. Selection for feed efficiency will result in distinct overall effects on the growth and carcass traits of Senepol heifers. Direct selection for lower RFI may reduce DMI and increase carcass fatness at the finishing stage, but it might also result in reduced growth and muscle deposition. Residual BW gain is associated with the highest weight gain and zero impact on REA and BF, however, it is linked to higher feed consumption. Thus, the most suitable feed efficiency indicator was RIG, as it promoted the greatest decrease in feed intake concomitant with faster growth, with a similar impact on carcass traits when compared to the other feed efficiency indicators.

Water requirements of beef production can be reduced by genetic selection.

Growing concerns regarding sustainability in agriculture include the availability of drinking water, which is putting pressure on livestock production, especially the beef sector, for more efficient practices. Thus, genetic parameters were estimated for traits related to water intake and water use efficiency in Senepol cattle. Senepol females (n = 925) and males (n = 191) were evaluated in performance tests carried out from 2014 to 2019. Daily dry matter intake (DMI) and water intake (WI) were recorded by electronic feed and water bunks (Intergado Ltd.). Other traits assessed included average daily gain (ADG); mid-test metabolic BW (BW0.75); residual water intake based on ADG (RWIADG), estimated as the residual of the linear regression equation of WI on ADG and BW0.75; residual water intake based on DMI (RWIDMI), estimated as the residual of the linear regression equation of WI on DMI and BW0.75 (RWIDMI); water conversion ratio (= WI/ADG); gross water efficiency (GWE = ADG/WI); residual feed intake estimated as the residual of the linear regression equation of DMI on ADG and BW0.75 (RFI); feed conversion ratio (= DMI/ADG) and gross feed efficiency. Genetic (co)variances were estimated with bivariate analyses. The heritabilities for WI, RWIADG and RWIDMI were 0.38, 0.36 and 0.33, respectively. Water conversion ratio, RWIADG and RWIDMI showed positive genetic and phenotypic correlations with WI, whereas GWE was negatively correlated with WI, suggesting that traits related to water use efficiency may be useful to identify cattle with reduced WI. Water intake showed positive genetic (r = 0.79) and phenotypic (r = 0.60) correlations with DMI, suggesting the use of WI to estimate DMI in future studies. Both RWIADG and RWIDMI were genetically correlated with RFI (0.67 and 0.57, respectively) and ADG (0.49 and 0.44, respectively), showing that RWI is positively associated with feed efficiency, but has an antagonistic relationship with growth. This antagonism, however, may be managed using selection indexes. Genetic improvement of water use efficiency in Senepol cattle is possible through selection and may reduce the water requirements of beef production systems.

Analog model for quantum gravity effects: phonons in random fluids.

We describe an analog model for quantum gravity effects in condensed matter physics. The situation discussed is that of phonons propagating in a fluid with a random velocity wave equation. We consider that there are random fluctuations in the reciprocal of the bulk modulus of the system and study free phonons in the presence of Gaussian colored noise with zero mean. We show that, in this model, after performing the random averages over the noise function a free conventional scalar quantum field theory describing free phonons becomes a self-interacting model.

Simple screening tests for detection of carbapenemases in clinical isolates of nonfermentative Gram-negative bacteria.

BACKGROUND & OBJECTIVE: The production of carbapenemases is an important mechanism responsible for the carbapenem resistance. A simple and inexpensive testing method for screening of carbapenemase producers is essential. A prospective study was undertaken to detect metallo-beta-lactamases (MBLs) and AmpC beta-lactamases in nonfermentative Gram negative bacteria and to evaluate the various methods for detection of carbapenemases and MBLs. METHODS: A total of 100 Acinetobacter spp. (78 A. baumannii and 22 A. lwoffii) and 140 Pseudomonas spp. (103 P. aeruginosa and 37 other Pseudomonas spp.) were screened for meropenem resistance by Kirby-Bauer disc diffusion method. Modified Hodge test, EDTA disk synergy (EDS) test and AmpC disk test were used for the detection of carbapenemases, MBLs and AmpC beta-lactamases, respectively. RESULTS: Forty six (59.0%) A. baumannii, 7 (31.8%) A. lwoffii, 32 (31.1%) P. aeruginosa and 7 (18.9%) Pseudomonas spp. were resistant to meropenem. Among the 32 meropenem resistant P. aeruginosa, 15 (46.9%) were AmpC beta-lactamase producers, 16 (50.0%) MBL producers by EDS test, but only 9 (28.1%) found positive for carbapenemases by modified Hodge test. Among the 46 meropenem resistant A. baumannii, 31 (67.4%) were AmpC beta-lactamase producers, 3 (6.5%) MBL producers, but only 1 (14.3%) was positive for carbapenemases by modified Hodge test. One P. aeruginosa was positive for carbapenemase by modified Hodge test, but was negative for MBL and AmpC beta-lactamase. INTERPRETATION & CONCLUSION: MBL production is an important mechanism of carbapenem resistance among Pseudomonas species but not among Acinetobacter species. EDS is more sensitive for detection of MBLs than modifi ed Hodge test. Both EDTA-meropenem and EDTA-ceftazidime combination must be used to detect all the MBL producers. Carbapenemases other than MBL may also be responsible for carbapenem resistance. AmpC beta-lactamase is also a contributory factor for carbapenem resistance among the isolates in the hospital.

Crossbreeding applied to systems of beef cattle production to improve performance traits and carcass quality.

Crossbreeding represents an important technique to improve growth, beef quality and adaptability in beef production systems in tropical countries. The aim of this study was to evaluate sire and dam breed effects on performance and carcass traits of crossbred cattle produced in a tropical environment. Heifers and steers were evaluated during the pre-weaning, the post-weaning (n = 173) and the finishing phase (n = 123). Animals were produced by mating Nellore (N_N), Angus × Nellore (A_N) and Caracu × Nellore (C_N) dams with Braford, Charbray and Caracu sires. After weaning, animals were raised grazing on Marandu grass for 12 months; thereafter they were housed in individual pens and finished in a feedlot, receiving a total mixed ration. Ultrasound carcass evaluations were performed to determine ribeye area (R_A), backfat thickness (B_T) and rump fat thickness (R_T). A_N progeny were heavier at birth than N_N (P < 0.05), and Braford progeny had greater birth BW than Caracu (P < 0.05). Greater weaning BW was observed in the A_N and C_N offspring compared to N_N (P < 0.01). Greater average daily gain during the post-weaning period was verified in the N_N progeny compared to C_N (P < 0.05). No dam or sire breed effects were observed for BW at the end of the post-weaning period (P > 0.05). Progeny of N_N cows had greater B_T (P < 0.05) and R_T (P < 0.01) at the end of the post-weaning period in relation to C_N. Greater R_A was observed in the Caracu progeny than in the Braford (P < 0.05), which showed greater R_T than the Charbray progeny at the end of the post-weaning period (P < 0.05). No dam or sire breed effects were verified for final BW at the feedlot or for feed efficiency traits (P > 0.05). A_N progeny were superior in final B_T compared to C_N (P < 0.01), and Braford progeny had greater R_T at the end of finishing than Charbray (P = 0.05). The use of crossbred dams allows an increase in productivity until weaning, but this is not maintained in the post-weaning and finishing periods. The use of Braford sires produces similar growth performance in the different stages of the production system to those seen with Charbray and Caracu sires but generates animals with higher fat thickness at the end of finishing, which may improve carcass quality and commercial value.