Resumo: O objetivo deste trabalho foi avaliar os mecanismos de resistência aos antimicrobianos β-lactâmicos em 251 amostras de Staphylococcus coagulase-negativa (CoNS) isolados de cabras com mastite subclínica, bem como determinar a sensibilidade e a especificidade dos testes de nitrocefina e difusão em disco para detectar a resistência à penicilina, em comparação à reação em cadeia da polimerase (PCR). As amostras foram avaliadas quanto à presença dos genes blaZ e mecA, à produção de β-lactamase e à susceptibilidade à penicilina. Do total de isolados, 228 (91%) apresentaram o gene blaZ e, dentre estes, 144 (63%) foram positivos para β-lactamase. A resistência à penicilina foi observada em 125 isolados e, destes, 96,8% apresentaram o gene blaZ. A sensibilidade dos testes fenotípicos para detectar a produção de β-lactamase foi baixa, mas a sua especificidade foi alta; o coeficiente Kappa mostrou leve concordância entre os testes fenotípicos e a PCR. O gene mecA foi detectado em apenas 3% dos isolados, que foram identificados como pertencentes às espécies: S. capitis subsp. ureolyticus, S. caprae, S. warneri, S. sciuri, S. simulans e S. cohnii subsp. urealyticum. Staphylococcus coagulase-negativa são importantes agentes etiológicos da mastite caprina e apresentam genes blaZ e mecA de resistência aos antimicrobianos β-lactâmicos. A sensibilidade dos testes de nitrocefina e difusão em disco para detectar a resistência à penicilina é baixa em relação à da PCR.

Abstract: The objective of this work was to evaluate resistance mechanisms to β-lactam antimicrobials in 251 strains of coagulase-negative Staphylococcus (CoNS) isolated from subclinical goat mastitis, as well as to determine the sensitivity and specificity of the nitrocefin and disk diffusion methods to detect penicillin resistance, in comparison with the polymerase chain reaction (PCR). The isolates were evaluated for the presence of the blaZ and mecA genes, β-lactamase production, and susceptibility to penicillin. Of the total isolates, 228 (91%) carried the blaZ gene and, among these, 144 (63%) were positive for β-lactamase production. Resistance to penicillin was observed in 125 of the isolates, of which 96.8% carried the blaZ gene. The sensitivity of the phenotypic methods to detect β-lactamase production was low, but their specificity was high; the Kappa coefficient showed a poor agreement between the phenotypic methods and PCR. The mecA gene was detected in only 3% of the isolates, which were identified as belonging to the species: S. capitis subsp. ureolyticus, S. caprae, S. warneri, S. sciuri, S. simulans, and S. cohnii subsp. urealyticum. Coagulase-negative Staphylococcus are important mastitis-causing pathogens in goat and harbor the blaZ and mecA genes related to resistance to β-lactam antimicrobials. The sensitivity of the nitrocefin and disk diffusion methods to detect penicillin resistance is low in relation to that of PCR.

RESUMO Objetivou-se com este estudo identificar, por meio da análise de componentes principais e análise de agrupamento, as variáveis capazes de explicar a variabilidade na qualidade e na produção de leite de vacas Holandesas. Foram utilizados dados mensais de controle leiteiro, de três fazendas comerciais localizadas na região Agreste do estado de Pernambuco, Brasil, obtidos no período de 2007 a 2017. Foram analisadas 5.872 informações de produção e componentes do leite, e de escore de células somáticas (SCS), quanto à possibilidade de formação de grupos que pudessem ser destacados pela similaridade e verificar a capacidade discriminante dessas características nos grupos. Os métodos K-means e Ward.D2, baseados na análise da distância euclidiana e dos componentes principais (PCA), foram utilizados para indicar as fontes de variação que diferenciaram os grupos. Foi observado que os primeiros três componentes principais explicaram 79,69% da variabilidade dos dados. A variável que mais contribuiu no primeiro componente foi o teor de sólidos totais com 29,66%. No segundo componente, a lactose, se destacou com uma contribuição de 49,43%. Na análise de agrupamento, três clusters diferiram em relação a todas as características (p<0,001), o cluster 2, por exemplo, concentrou 43,15% (2.534) das informações, agrupando animais com um menor SCS e maior lactose e produção de leite. As variáveis sólidos totais, lactose e gordura foram as que mais contribuíram dentro dos três componentes selecionados. A ACP e agrupamento podem ser ferramentas úteis na obtenção de características efetivas, sendo três fatores considerados importantes para explicar a relação entre produção e qualidade do leite.

ABSTRACT Using multivariate analyses, this study attempted to identify important traits explaining the relationship between milk production and quality produced by Holstein cows. Monthly milk records from three commercial dairy farms located in the Agreste region of Pernambuco, Brazil, collected in the period from 2007 to 2017, were used. A total of 5,872 observations regarding milk production, milk components and somatic cell score (SCS) were analyzed using principal component analysis (PCA) and cluster analysis. According to the former analysis, the first three principal components explained 79.69% of the total variation. Total solids content contributed 29.66% of the variation in the first principal component, while lactose content contributed 49.43% of the variation in the second principal component. According to the latter analysis, three clusters differed for all characteristics (p<0.001) and cluster 2 concentrated 43.15% (2,534) of the information with lower SCS and higher lactose content and milk production. Total solids, lactose and fat were considered the most representative traits explaining the variability of the data set. The multivariate techniques used in this study proved useful in obtaining effective characteristics, with three factors considered important in explaining the relationship between Holstein cows’ milk production and quality.

ABSTRACT. The purpose of this study was to evaluate the monthly milk production and quality of buffaloes from two milk production systems in the Brazilian northeast using the multivariate analysis: principal component analysis (PCA). A total of 2,506 individual milk recordings were performed in two production systems, containing information on milk production (kg day-1), fat, protein, lactose and total solids counts and somatic cell count (SCC). There were positive correlations between the fat content and the contents of total solids (TS) and protein, and of TS and protein. From the PCA, two main components (PC1 and PC2) were identified, explaining 67.71% of the total variation. The fat, protein, lactose and ST level, represented by PC1, explain 46.18% of the total variance, and were an indicator of milk nutritional quality. The CP2, composed of milk production, SCC and production systems, explains 21.53% of the total variance, and was indicative of herd health. PCA results may be useful in dairy buffalo breeding programs, and a reduced number of variables are necessary to assess the nutritional quality of milk and herd health.

RESUMO Em rebanhos leiteiros, um dos objetivos mais importantes da seleção é a melhoria da produção e composição do leite. Vários estudos demonstraram que os genes candidatos da kappa-caseína (CSN3) e da β-lactoglobulina (β-LG) estão associados a produção de leite, qualidade do leite e características de saúde em animais leiteiros. Portanto, o objetivo deste estudo foi detectar polimorfismos nos genes CSN3 e β-LG e avaliar possíveis associaçoes desses polimorfismos com a produção de leite em até 305 dias (305MY) e a capacidade de transmissão prevista (PTA) de leite em bovinos da raça Girolando. No total, 138 touros e 729 vacas (n = 867) foram amostrados. A genotipagem foi realizada pelo método PCR-RFLP utilizando as enzimas HinfI e HaeIII para os genes CSN3 e β-LG, respectivamente. Os resultados estatísticos revelaram dois alelos A e B para ambos os genes. Os genotipos e alelos mais frequentes para os genes CSN3 e β-LG foram respectivamente: AA (0,7324) e A (0,8558) e AB (0,4827) e A (0,5017). O teste x2 revelou que os dois loci estavam em equilibrio de Hardy-Weinberg (p <0,001). Os efeitos de substituiçao alélica para as variantes nao foram significativos para as características 305 MY e PTA para 305MY (p> 0,05). Portanto, as variantes alélicas identificadas nos genes β-LG e CSN3 devem ser mais investigadas antes de serem incluidas nos programas de melhoramento desenhados para bovinos leiteiros Girolando objetivando melhorar as características do leite analisadas no presente estudo.

SUMMARY In dairy farm animals, one the most important goal of the selection is the improvement of milk yield and composition. Several studies have demonstrated that the candidate genes of the kappa-casein (CSN3) and β - lactoglobulin (β-LG) are associated with milk yield, milk quality and health traits in dairy animals. Therefore the aim of this study was to detect polymorphisms in CSN3 and β-LG genes and its association with milk yield in up to 305 days (305MY) and predicted transmission capacity (PTA) for 305MY in Girolando cattle. Totally, 138 bulls and 729 cows (n=867) were sampled. The genotypes of both genes were obtained by the PCR-RFLP method using HinfI and HaeIII enzymes for CSN3 and β-LG genes, respectively. Statistical results revealed two alleles A and B for both genes. The genotypes and alleles more frequents for CSN3 and β-LG genes were respectively: AA (0.7324) and A (0.8558), and AB (0.4827) and A (0.5017). The x2 test revealed that the two loci were at Hardy-Weinberg equilibrium (p<0.001). The allele substitution effects for the variants were not significant on 305MY and PTA for 305MY (p>0.05). The allele variants of β-LG and CSN3 might be more investigated before include them into future breeding schemes designed for Girolando dairy cattle with objective of improving milk traits as milk yield in up to 305 days (305MY) and predicted transmission capacity (PTA) for 305MY..

RESUMO Para investigar a relação entre contagens de células somáticas (CCS) e características atualmente selecionadas (produção de leite, gordura, proteína, lactose, sólidos totais e sólidos não gordurosos) em vacas leiteiras holandesas em clima semiárido brasileiro, foram coletados dados de 272 vacas de janeiro de 2007 a dezembro 2016. As fazendas foram localizadas na região Agreste do estado de Pernambuco, cujas características climáticas, de acordo com o Instituto Nacional de meteorologia-INMET, foram: temperatura média anual de 25,21°C; precipitação média anual de 562,07 mm e umidade relativa média anual de 75,61%. Foi analisado um total de 4.586 registros de contagens de células somáticas (CCS) no leite, produção de leite e componentes lácteos. A CCS foi transformada logaritmicamente em ECS ECS = log 2 ( CCS / 100 . 000 ) + 3 ) . Dez ECS foram obtidos para determinar seus efeitos sobre a produção e composição do leite. Os dados foram processados usando os comandos PROC GLM e PROC CORR do SAS. Os resultados mostraram correlações positivas entre ECS e gordura, proteína, sólidos totais e teores de sólidos não gordurosos, enquanto o ECS e o teor de lactose e o rendimento do leite foram correlacionados negativamente. A maior produção de leite (34,43 kg/vaca/dia) foi obtida para o menor ECS (0; 0 a 24 células x 1000/mL). A produção de leite e a lactose diminuíram quando os percentuais de proteína e gordura aumentaram, principalmente quando o ECS foi acima de cinco. O aumento da ECS influenciou negativamente a produção e a composição do leite em vacas de holandesas criadas no clima semiárido brasileiro.

SUMMARY This study aimed to investigate the relationship among somatic cell scores (SCS) and currently selected traits (milk yield, and fat, protein, lactose, total solids and no-fat-solids contents) in Holstein dairy cows in a semi-arid climate. The data were collected from available records of 272 Holstein cows from January 2007 to December 2016. Farms were located in Agreste region of Pernambuco whose climatic characteristics according to Instituto Nacional de Meteorologia-INMET were: average annual temperature of 25.21 °C; average annual precipitation 562.07 mm, and average annual relative humidity 75.61%.. A total of 4,586 records of somatic cell counts (SCC) in the milk, milk yield and milk components was analyzed. The SCC was transformed logarithmically into SCS SCS = log 2 ( SCC / 100 , 000 ) + 3 ) before statistical investigation. Ten SCS were obtained for determining their effects on milk yield and composition. Data were processed using PROC GLM and PROC CORR procedures in SAS. Results showed positive correlations among SCS and fat, protein, total solids and solids-non-fat contents, while the SCS and lactose content and milk yield were negatively correlated. The highest milk yield (34.43 kg/cow/day) was obtained for the lowest SCS (0; 0 to 24 cells x 1000/mL). The milk yield and lactose decreased while protein and fat contents increased when SCS increased mostly above score five (400 to 799 cells x 1000/mL). It was observed that the increase in SCS influenced negatively milk yield and composition in Holstein cows created in the semi-arid climate in Brazil.

Brazilian goats are generally kept in small herds and extensive rearing systems, mainly in the northeastern region of the country. Despite production improvement in recent years, the lack of pedigree control has affected genetic progress. This study aimed to validate a panel of 16 microsatellites for parentage testing in locally adapted and commercial goats breeds raised in Brazil, as well as to compare its efficiency with the panel recommended by the Brazilian Ministry of Agriculture, Livestock and Supplies (MAPA) in 2004. The number of alleles and expected heterozygosity (He) per marker ranged from four to 18, and from 0.051 to 0.831, respectively. Using all markers, 100% of parentage cases of the validation dataset were resolved with a strict confidence level of 95%. The 16 microsatellites panel showed adequate exclusion power (99.99%) and identity accuracy (99.99%). Suggestions for improvement of the marker panel endorsed by MAPA are provided.

This study estimated the genetic diversity and structure of 12 genetic groups (GG) of locally adapted and specialized pigs in the state of Pernambuco using 22 microsatellite markers. Nine locally adapted breeds (Baé, Caruncho, Canastra, Canastrão, Mamelado, Moura, Nilo, Piau and UDB (Undefined Breed)) and 3 specialized breeds (Duroc, Landrace and Large White), totaling 190 animals, were analyzed. The Analysis of Molecular Variance (AMOVA) showed that 3.2% of the total variation was due to differences between genetic groups, and 3.6% to differences between local and commercial pigs. One hundred and ninety eight alleles were identified and apart from the Large White breed, all GG presented Hardy-Weinberg Equilibrium deviations for some loci. The total and effective allele means were lower for Duroc (3.65 and 3.01) and higher for UDB (8.89 and 4.53) and Canastra (8.61 and 4.58). Using Nei's standard genetic distance and the UPGMA method, it was possible to observe that the Landrace breed was grouped with the local genetic groups Canastra, Moura, Canastrão, Baé and Caruncho. Due to the complex admixture pattern, the genetic variability of the 12 genetic groups can be analyzed by distributing the individuals into two populations as demonstrated by a Bayesian analysis, corroborating the results from AMOVA, which revealed a low level of genetic differentiation between the inferred populations.