Evaluation of the contribution of the placentomal fusion during gestation in cattle

The placenta of mammals is a structure formed by the juxtaposition of the fetal membranes and the maternal tissues. The main function of the placenta is to regulate the physiological interchange between the fetus and the mother as well as to operate as an important endocrine organ during the gestation. The placentomal fusions were characterized throughout gestation of cattle using macroscopic, histological and flow cytometry analyses. Analyzing the cell cycle phases with a flow cytometry, a balance between the G2M phase and apoptosis was observed, suggesting that the placentomal fusions do not interfere in the placentary maturation process, which is a pre-requirement for the fetal-maternal disconnection and the release of fetal membrane. (C) 2011 Elsevier B.V. All rights reserved.

Aflatoxins and cyclopiazonic acid in feed and milk from dairy farms in Sao Paulo, Brazil

The occurrence of aflatoxins (AF) B(1), B(2), G(1), G(2) and cyclopiazonic acid (CPA) in feeds, and AFM(1) and CPA in milk was determined in dairy farms located in the northeastern region of Sao Paulo state, Brazil, between October 2005 and February 2006. AF and CPA determinations were performed by HPLC. AFB(1) was found in 42% of feed at levels or 1.0-26.4 mu g kg(-1) (mean: 7.1 +/- 7.2 mu g kg(-1)). The concentrations of AFM(1) in raw milk varied between 0.010 and 0.645 mu g l(-1) (mean: 0.104 +/- 0.138 mu g l(-1)). Only one sample was above the tolerance limit adopted in Brazil (0.50 mu g l(-1)) for AFM(1) in milk. Regarding CPA in feed, six (12%) samples showed concentrations of 12.5-1533 mu g kg(-1) (mean: 57.6 +/- 48.7 mu g kg(-1)). CPA was detected in only three milk samples (6%) at levels of 6.4, 8.8 and 9.1 mu g l(-1). Concentrations of aflatoxins and CPA in feed and milk were relatively low, although the high frequency of both mycotoxins indicates the necessity to continuously monitor dairy farms to prevent contamination of feed ingredients.

Antimicrobial susceptibility of coagulase-negative Staphylococci isolated from mastitic cattle in Brazil

Um total de 109 cepas de Staphylococci coagulase-negativa foi isolado de leite de vacas com mastite clínica e subclínica, em 35 fazendas, situadas em nove estados brasileiros, no período de fevereiro a maio de 2005. Os isolados foram investigados em relação a susceptibilidade in vitro a diversos agentes antimicrobianos. A resistência à penicilina foi a observação mais freqüente (93,5%), seguida por sulfonamida (88,9%), novobiocina (88,6%) e ampicilina (85,3%). Todas as cepas examinadas mostraram resistência a pelo menos uma das drogas antimicrobianas testadas. Cepas apresentando resistência múltipla foram extremamente comuns, com 10,0% dos microrganismos isolados apresentando resistência a todas as drogas antimicrobianas. Os resultados obtidos indicaram que as cepas de Staphylococci coagulase-negativas, isoladas no Brasil, apresentaram um alto grau de resistência a antimicrobianos. Estes resultados são, provavelmente, uma conseqüência da pressão devida ao uso intensivo de drogas antimicrobianas.

Occurrence of Staphylococcus aureus in raw milk produced in dairy farms in São Paulo state, Brazil

The objective of the present study was to evaluate the occurrence of Staphylococcus aureus in milk produced in 37 farms located in the regions of Ribeirão Preto and São Carlos, state of São Paulo, Brazil. Two-hundred and eight samples of milk from individual cows showing subclinical mastitis, and 37 samples of bulk tank milk were analyzed. S. aureus strains were detected in 18 (7.3%) milk samples: 14 (6.7%) from samples of individual cows, and 4 (10.8%) from bulk tank milk. Two individual milk samples (14.3%) and two bulk milk samples contained enterotoxigenic S. aureus. PFGE analysis revealed the genetic heterogeneity of the strains isolated from raw milk, which presented to 13 S. aureus patterns. Results confirmed the potential transmission of staphylococcal food poisoning to consumers via milk of cows affected by subclinical mastitis, mainly when raw milk is ingested.

Effects of dietary energy and nitrogen supplements on rumen fermentation and protozoa population in buffalo and zebu cattle

The effects were assessed of two energy sources in concentrate (ground grain corn vs. citrus pulp) and two nitrogen sources (soybean meal vs. urea) on rumen metabolism in four buffaloes and four zebu cattle (Nellore) with rumen cannula and fed in a 4 × 4 Latin square design with feeds containing 60% sugar cane. Energy supplements had no effect on the rumen ammonia concentration in cattle, but ground grain corn promoted higher ammonia level than citrus pulp in buffalo. Urea produced higher ammonia level than soybean meal in both animal species. On average, the buffaloes maintained a lower rumen ammonia concentration (11.7 mg/dL) than the cattle (14.5 mg/dL). Buffaloes had lower production of acetic acid than cattle (58.7 vs. 61.6 mol/100 mol) and higher of propionic acid (27.4 vs. 23.6 mol/100 mol). There was no difference in the butyric acid production between the buffaloes (13.6 mol/100 mol) and cattle (14.8 mol/100 mol) and neither in the total volatile fatty acids concentration (82.5 vs. 83.6 mM, respectively). The energy or nitrogen sources had no effect on rumen protozoa count in either animal species. The zebu cattle had higher rumen protozoa population (8.8 × 10(5)/mL) than the buffaloes (6.1 × 10(5)/mL). The rumen protozoa population differed between the animal species, except for Dasytricha and Charonina. The buffaloes had a lower Entodinium population than the cattle (61.0 vs 84.9%, respectively) and a greater percentage of species belonging to the Diplodiniinae subfamily than the cattle (28.6 vs. 1.4%, respectively). In cattle, ground corn is a better energy source than citrus pulp for use by Entodinium and Diplodiniinae. In the buffaloes, the Entodinium are favored by urea and Diplodiniinae species by soybean meal.

Tuberculose bovina no Estado da Paraíba: estudo retrospectivo

O objetivo do presente trabalho foi determinar a frequência de propriedades positivas (focos) e de animais positivos para a tuberculose bovina no Estado da Paraíba. Foram utilizados dados da Agência de Defesa Agropecuária do Estado, coletados de suas 23 microrregiões, durante o período de janeiro de 2008 a julho de 2009. Durante esse período, foram examinadas 10.963 propriedades e 54.472 bovinos foram submetidos ao teste de tuberculinização. Para o diagnóstico foi utilizada, como prova de triagem, a tuberculinização cervical simples para gado de leite e a tuberculinização na prega caudal para gado de corte; como prova confirmatória foi utilizada a tuberculinização cervical comparativa. Uma propriedade foi considerada foco quando apresentou pelo menos um animal soropositivo. Das propriedades investigadas, 62 (0,57%) apresentaram pelo menos um animal positivo e dos animais analisados, 136 (0,25%) foram positivos. Houve diferença significativa (p<0,001) na proporção de fêmeas (0,32%) e machos (0,04%) positivos. A despeito da baixa freqüência de focos de brucelose e de animais soropositivos, é necessária a condução de medidas que incluem a conscientização dos produtores, fiscalização nas barreiras sanitárias e levantamentos periódicos da situação epidemiológica desta doença, principalmente nas microrregiões com maior frequência da infecção, com o objetivo de evitar, ou pelo menos minimizar, a disseminação do agente.

Achados clínico patológicos durante um surto de disenteria de inverno em bovinos no Rio Grande do Sul

Descreve-se um surto de disenteria de inverno que afetou 10 vacas leiteiras de uma propriedade localizada em Viamão, Rio Grande do Sul. O quadro clínico caracterizou-se por uma diarréia inicialmente líquida esverdeada com estrias de sangue e muco, evoluindo, em alguns animais, para uma diarréia de coloração marrom escura à sanguinolenta, que persistiu, em média, cinco dias. Drástica diminuição na produção de leite e no consumo de alimentos, além de graus variados de depressão também foram observados. Apenas um dos 10 animais afetados morreu. Durante a necropsia, observaram-se mucosas pálidas, conteúdo sanguinolento com presença de grande quantidade de coágulos, principalmente no cólon espiral e petéquias na mucosa do cólon. Os principais achados histológicos foram encontradas no cólon espiral, onde havia criptas dilatadas, sem epitélio de revestimento ou revestidas por epitélio pavimentoso e/ou cuboidal, por vezes com núcleos grandes e nucléolos proeminentes. Algumas criptas eram preenchidas por debris necróticos e polimorfonucleares. Na imuno-histoquímica com anticorpo monoclonal para coronavírus bovino (8F2) em cortes do cólon espiral, havia marcações positivas no citoplasma de enterócitos das criptas, nos debris necróticos destas e em macrófagos na lâmina própria.

Situação epidemiológica da brucelose bovina no Distrito Federal

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Distrito Federal (DF). No total foram amostrados 2.019 animais, provenientes de 278 propriedades. Em cada propriedade visitada aplicou-se um questionário epidemiológico para verificar o tipo de exploração e as práticas de criação e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo utilizado foi o da triagem com o teste do antígeno acidificado tamponado e a confirmação dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo quando pelo menos um animal foi reagente às duas provas sorológicas. A prevalência no DF foi de 2,5% [1,0-5,1%] para propriedades e de 0,16% [0,04-0,28%] para animais. Em razão dos resultados encontrados, que permitem pensar em estratégias de erradicação, recomenda-se que o DF intensifique o diagnóstico de brucelose, tanto na forma de testes sorológicos sistemáticos como pela introdução de mecanismos de detecção rápida em laticínios, em ambos os casos a fim de aumentar o número de propriedades certificadas como livres da doença e melhorar a sensibilidade do sistema de vigilância ativa.

Productive performance and milk protein fraction composition of dairy cows supplemented with sodium monensin

The objective of this work was to evaluate the levels of sodium monensin on lactating cows and their effects on productive performance and milk protein fraction composition. It was used 12 Holstein cows, distributed in four balanced 3 &#215; 3 Latin squares, and fed three diets: one control without monensin, and two diets with monensin at the levels of 24 or 48 mg/kg DM added to the concentrate. Milk production was daily measured throughout the entire experimental period. The samples used for analysis of milk composition were collected on two alternated days from the two daily milking. Non-protein nitrogen, total nitrogen and non-casein nitrogen contents were directly evaluated in the milk, and casein, whey protein and true protein contents were indirectly determined. The use of monensin in the rations reduced dry matter and nutrient intake, especially when diet with 48 mg/kg of dry matter was given. The ration with 24 mg/kg of DM increased milk production, with or without correction, and also fat and lactose yield, and it improved productive efficiency. The levels of monensin in the ratios did not influence contents of milk crude protein, non-protein nitrogen, non-casein nitrogen, true protein, casein, casein/true protein ratio, whey protein, and of all those fractions expressed as percentage of crude protein. The utilization of monensin in the ratio at the dose of 24 mg/kg of DM influences positively the productive performance of lactating cows, and it does not influence the composition of milk protein fractions.

Productive performance and composition of milk protein fraction in dairy cows supplemented with fat sources

The objective of this study was to evaluate the use of fat sources in rations for lactating cows on the productive performance and composition of milk protein fraction. Twelve Holstein cows were used, grouped in three balanced 4 &#215; 4 Latin squares, fed with the following rations: control; refined soybean oil; whole raw soybean; and calcium salts of unsaturated fatty acid (Megalac-E). Dry matter and nutrient intake, and daily milk production were evaluated. The samples used to analyze milk composition were collected in two alternate days and were obtained from two daily milking. Milk composition and total nitrogen, non-protein nitrogen and non-casein nitrogen ratios were analyzed. The casein, serum protein and true protein ratios were obtained by difference. Dry matter and nutrient intakes were lower when cows received the diet containing calcium salts of fatty acids, in relation to the control diet. Among the diets with fat sources, the one with whole raw soybean and calcium salts decreased milk production. There was no effect of fat sources added to the diet on crude protein, non-protein nitrogen, non-casein nitrogen, true protein, casein, casein/milk true protein ratio and serum protein. Similarly, the experimental diets did not influence the protein fractions when expressed in percentage of milk crude protein. The utilization of fat sources in diets changes milk production and composition of lactating cows, but does not influence the composition of milk protein fractions.

Genome wide scan for quantitative trait loci affecting tick resistance in cattle (Bos taurus x Bos indicus)

Background : In tropical countries, losses caused by bovine tick Rhipicephalus (Boophilus) microplus infestation have a tremendous economic impact on cattle production systems. Genetic variation between Bos taurus and Bos indicus to tick resistance and molecular biology tools might allow for the identification of molecular markers linked to resistance traits that could be used as an auxiliary tool in selection programs. The objective of this work was to identify QTL associated with tick resistance/susceptibility in a bovine F2 population derived from the Gyr (Bos indicus) x Holstein (Bos taurus) cross. Results: Through a whole genome scan with microsatellite markers, we were able to map six genomic regions associated with bovine tick resistance. For most QTL, we have found that depending on the tick evaluation season (dry and rainy) different sets of genes could be involved in the resistance mechanism. We identified dry season specific QTL on BTA 2 and 10, rainy season specific QTL on BTA 5, 11 and 27. We also found a highly significant genome wide QTL for both dry and rainy seasons in the central region of BTA 23. Conclusions: The experimental F2 population derived from Gyr x Holstein cross successfully allowed the identification of six highly significant QTL associated with tick resistance in cattle. QTL located on BTA 23 might be related with the bovine histocompatibility complex. Further investigation of these QTL will help to isolate candidate genes involved with tick resistance in cattle.

Predictive values of aspartate aminotransferase and gamma-glutamyl transferase for the hepatic accumulation of copper in cattle and buffalo

Ten cattle and 10 buffalo were divided into 2 groups (control [n = 8] and experimental [n = 12]) that received daily administration of copper. Three hepatic biopsies and blood samples were performed on days 0, 45, and 105. The concentration of hepatic copper was determined by spectrophotometric atomic absorption, and the activities of aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) were analyzed. Regression analyses were done to verify the possible existing relationship between enzymatic activity and concentration of hepatic copper. Sensitivity, specificity, accuracy, and positive and negative predictive values were determined. The serum activities of AST and GGT had coefficients of determination that were excellent predictive indicators of hepatic copper accumulation in cattle, while only GGT serum activity was predictive of hepatic copper accumulation in buffalo. Elevated serum GGT activity may be indicative of increased concentrations of hepatic copper even in cattle and buffalo that appear to be clinically healthy. Thus, prophylactic measures can be implemented to prevent the onset of a hemolytic crisis that is characteristic of copper intoxication.

Molecular and geographic analyses of vampire bat-transmitted cattle rabies in central Brazil

Background: Vampire bats are important rabies virus vectors, causing critical problems in both the livestock industry and public health sector in Latin America. In order to assess the epidemiological characteristics of vampire bat-transmitted rabies, the authors conducted phylogenetic and geographical analyses using sequence data of a large number of cattle rabies isolates collected from a wide geographical area in Brazil. Methods: Partial nucleoprotein genes of rabies viruses isolated from 666 cattle and 18 vampire bats between 1987 and 2006 were sequenced and used for phylogenetic analysis. The genetic variants were plotted on topographical maps of Brazil. Results: In this study, 593 samples consisting of 24 genetic variants were analyzed. Regional localization of variants was observed, with the distribution of several variants found to be delimited by mountain ranges which served as geographic boundaries. The geographical distributions of vampire-bat and cattle isolates that were classified as the identical phylogenetic group were found to overlap with high certainty. Most of the samples analyzed in this study were isolated from adjacent areas linked by rivers. Conclusion: This study revealed the existence of several dozen regional variants associated with vampire bats in Brazil, with the distribution patterns of these variants found to be affected by mountain ranges and rivers. These results suggest that epidemiological characteristics of vampire bat-related rabies appear to be associated with the topographical and geographical characteristics of areas where cattle are maintained, and the factors affecting vampire bat ecology.

Consequences for the Bovine Embryo of Being Derived from a Spermatozoon Subjected to Post-Ejaculatory Aging and Heat Shock: Development to the Blastocyst Stage and Sex Ratio

The objective was to determine whether aging of sperm caused by incubation at normothermic (38.5 C) or heat shock (40 C) temperatures for 4 h prior to oocyte insemination affects sperm motility, fertilizing ability, competence of the resultant embryo to develop to the blastocyst stage and blastocyst sex ratio. In the first experiment, the percent of sperm that were motile was reduced by aging (P<0.001) and the reduction in motility was greater for sperm at 40 C compared to sperm at 38.5 C (P<0.01). In the second experiment, oocytes were inseminated with aged sperm. A smaller percent of oocytes fertilized with sperm aged at either temperature cleaved by Day 3 after insemination than oocytes fertilized with fresh sperm (P<0.05). There was no effect of sperm aging on the percent of oocytes or cleaved embryos that developed to the blastocyst stage. Aging of sperm before fertilization at 38.5 C reduced the percent of blastocysts that were male (P=0.08). In the third experiment, incubation of sperm at 38.5 C or 40 C for 4 h did not reduce fertilizing ability of sperm as determined by pronuclear formation at 18 h post insemination. In conclusion, aging of sperm reduced cleavage rate and the percent of blastocysts that were males but had no effect on the developmental capacity of the. embryo. The effect of aging on cleavage rate may represent reduced motility and errors occurring after fertilization and pronuclear formation. Aging at a temperature characteristic of maternal hyperthermia had little additional effect except that polyspermy was reduced. Results indicate that embryo competence for development to the blastocyst stage is independent of sperm damage as a result of aging for 4 h at normothermic or hyperthermic temperatures.

Recoleta uterina como estratégia para aumentar a taxa de embriões em fêmeas bovinas de corte e leite

Embryo recovery rate in superovulated cows after uterine flushing is lower than the ovulation rate, which contributes to the relative inefficiency of the conventional cervical recovery procedure. A simple and easy alternative to improve embryo recovery rate is the uterine re-flushing procedure. To evaluate the effect of re-flushing and the influence of breed and operator on bovine embryo recovery rate, 38 Nelore and 19 Jersey females were stimulated using FSH, with embryos being collected by one of two trained operators. At the end of flushing, the catheter was sealed and maintained into the uterine body, filled with flushing medium, while females were released to a paddock for 30 to 50 min, to be submitted to the re-flushing procedure by the same operator. A total of 599 structures were recovered out of 57 procedures, from which 423 (70.6%) were obtained in the first flushing and 176 (29.4%) after re-flushing. Mean recovery rates of 7.4 and 3.1 structures were obtained after the first and second flushing, respectively, for a total of 10.5 structures per cow. Structures were obtained in 73.6% ( 42 out of 57) of the re-flushing procedures. No breed effect was observed on total ova or embryo recovery, with 10.9 total ova collected from Jersey and 10.3 from Nelore females. Likewise, the embryo recovery rate obtained following uterine flushing or re-flushing did not differ either between Jersey (8.1 and 2.7) and Nelore (7.0 and 3.2) animals, or between operators A (7.5 and 3.3) and B (7.3 and 2.9), respectively. In conclusion, the uterine re-flushing procedure significantly increased the rate of embryo recovery in Jersey and Nelore females, with no operator influence being observed.