TLR4 Single Nucleotide Polymorphisms (SNPs) Associated with Salmonella Shedding in Pigs

Toll-like receptor 4 (TLR4) is a key factor in the innate immune recognition of lipopolysaccharide (LPS) from Gram-negative bacteria. Previous studies from our group identified differences in the expression profile of TLR4 and genes affected by the TLR4 signaling pathway among pigs that shed varying levels of Salmonella, a Gram-negative bacterium. Therefore, genetic variation in this gene may be involved with the host’s immune response to bacterial infections. The current study screened for single nucleotide polymorphisms (SNPs) in the TLR4 gene and tested their association with Salmonella fecal shedding

Use of postpartum body condition score to identify the most fertile beef cows raised in extensive operations

The assessment of postpartum body condition score in beef cattle may be a useful tool to recommend technologies to improve reproductive efficiency based on nutrition and reproductive management. The variability and repeatability of body condition scores between 60-90 d postpartum were investigated in order to verify the possibility that such assessments could indicate the inheritance of fertility in beef cows. In three consecutive years a total of 3721 cows predominantly Hereford purebreds and crossbreds, kept on natural pastures in seven farms in the southern region of Rio Grande do Sul, Brazil, were evaluated. More than 60% of these cows had intermediate to superior body condition score (scale of five classes), varying significantly among farms and years studied. A low repeatability of scores in the same animal in two or three consecutive years was found, refuting the possibility of direct selection for higher fertility as a function of body condition score. Although the scoring system does not define fertility phenotypes, it allows the identification of the one in every 200 cows with the characteristic of being pregnant and maintaining high body condition scores during three consecutive years, which may serve as base animals for future genome association studies employing single nucleotide polymorphisms

In vitro culture of parasitic stages of Haemonchus contortus = Cultivo in vitro de estádios parasitários de Haemonchus contortus

Haemonchus contortus is a constraint to sheep production. Seeking to reduce the use of hosts and produce parasitic stages in large-scale, a 42-day in vitro culture protocol of H. contortus third-stage larvae was optimized using Dulbecco’s modified Eagle’s medium (DMEM). In cell-free culture, larvae were maintained at 39.6°C, in acidic media (pH 6.1) for 3 or 6 days with Δ4-dafachronic acid followed by DMEM pH 7.4 supplemented or not with Fildes’ reagent. In DMEM pH 7.4 at 37°C, supplementation with Caco-2 cells was compared to Fildes. On Day 14, fourth-stage larvae (L4) development rates in acidic media supplemented (86.8-88.4%) or not (74.4-77.8%) with Fildes and in Caco-2 cell co-culture (92.6%) were similar, and superior to DMEM pH 7.4 with Fildes (0.0%). On Day 21, Caco-2 cell co-culture resulted in higher larvae differentiation (25.0%) and lower degeneration (13.9%) compared to acidic media (1.5-8.1% and 48.6-69.9%, respectively). This is the first report of prolonged in vitro culture of H. contortus larvae using commercial media in co-culture with Caco-2 cells. Although no progression to the adult stage, Caco-2 cell co-culture resulted in morphological differentiation of H. contortus L4 and larval viability for up to 28 days

Identification of novel loci associated with gastrointestinal parasite resistance in a Red Maasai x Dorper backcross population

Gastrointestinal (GI) parasitic infection is the main health constraint for small ruminant production, causing loss of weight and/or death. Red Maasai sheep have adapted to a tropical environment where extreme parasite exposure is a constant, especially with highly pathogenic Haemonchus contortus. This breed has been reported to be resistant to gastrointestinal parasite infection, hence it is considered an invaluable resource to study associations between host genetics and resistance. The aim of this study was to identify polymorphisms strongly associated with host resistance in a double backcross population derived from Red Maasai and Dorper sheep using a SNP-based GWAS analysis. The animals that were genotyped represented the most resistant and susceptible individuals based on the tails of phenotypic distribution (10% each) for average faecal egg counts (AVFEC). AVFEC, packed cell volume (AVPCV), and live weight (AVLWT) were adjusted for fixed effects and co-variables, and an association analysis was run using EMMAX. Revised significance levels were calculated using 100,000 permutation tests. The top five significant SNP markers with - log10 p-values >3.794 were observed on five different chromosomes for AVFEC, and BLUPPf90/PostGSf90 results confirmed EMMAX significant regions for this trait. One of these regions included a cluster of significant SNP on chromosome (Chr) 6 not in linkage disequilibrium to each other. This genomic location contains annotated genes involved in cytokine signalling, haemostasis and mucus biosynthesis. Only one association detected on Chr 7 was significant for both AVPCV and AVLWT. The results generated here reveal candidate immune variants for genes involved in differential response to infection and provide additional SNP marker information that has potential to aid selection of resistance to gastrointestinal parasites in sheep of a similar genetic background to the double backcross population

Investigation of indirect selection criteria and DNA markers for clean wool colour in sheep

In Experiment 1, progeny test data for 53 Corriedale sires and 1492 offspring were used to estimate heritabilities for and phenotypic and genetic correlations between yellow predictive colour (YPC), greasy (GFW) and clean fleece weight (CFW), Yield, mean fibre diameter (MFD), and Visual Score. Results showed a low heritability for YPC (0.28±0.06), and positive genetic correlations of YPC with CFW or MFD. Direct selection against YPC was expected to decrease CFW and to decrease MFD. Although reductions in MFD are economically beneficial, reductions in CFW would translate in large net losses in wool income. Visual Score and YPC were strongly genetically correlated, however using Visual Score as an indirect selection criterium for YPC would be expected to produce even greater correlated responses in CFW, resulting in bigger economic losses, than when YPC was used. The same flock was used for Experiment 2, where 440 offspring from 19 Corriedale sires were included in the analyses of heritability for and phenotypic and genetic correlations between wool colour traits: clean wool colour (CWC), brightness (Y), YPC, and Visual Score; wool production traits: GFW, CFW, Yield, MFD; suint traits: suint percentage and potassium (K) and sodium (Na) concentrations in suint, and physiological traits: potassium and sodium concentrations in plasma, red blood cells, and skin. The main objective of this study was to find suitable indirect selection criteria for clean wool colour. The heritability of CWC was estimated at 0.27±0.13. Clean wool colour showed strong positive genetic correlations with CFW and MFD, thus direct selection against CWC was also expected to reduce CFW and MFD. A high genetic correlation between YPC and CWC was observed, indicating that YPC could be a suitable indirect selection criterium for CWC. However, the heritability for YPC in this experiment was lower than that observed in Experiment I and direct selection against CWC was predicted to produce faster genetic improvements in CWC than that expected under indirect selection. Brightness, skin K, Visual Score, YPC and suint K were amongst the best indirect selection criteria for clean wool colour. However, selection using these traits was expected to reduce CWC from 58% to 49% of that estimated for direct selection. Suint traits were highly genetically correlated to YPC. Suint K, but not suint percentage, was found to have a high genetic correlation with CWe. Plasma K was strongly genetically correlated to YPC and suint K, which suggests that plasma is the pool of potassium that is excreted through the sweat glands. Skin K was considered an unreliable predictor of suint K. A selection index was calculated, with CFW, MFD and CWC being both selection criteria and breeding objective traits. The index estimated was I₁ = +1.21CFW +0.11MFD +0.42CWC. A second selection index having CFW, MFD and CWC as breeding objective traits and CFW, MFD and YPC as the selection criteria was derived as I₂ = +1.22CFW +0.14MFD +0.19YPC. The high relative economic value (REV's) of CFW compared to the other traits fitted in these indices caused positive expected correlated responses for all traits, therefore undesirable genetic gains were predicted for CWC. A third index having CFW, MFD and CWC as both selection criteria and breeding objective traits, where CFW was restricted to nil genetic change, was estimated at: I₃ = +0.23CFW -0.04MFD -0.01CWC. This index was expected to cause a negligible genetic gain for CWC (-0.04 Y-Z units/year). The results showed that the most effective way to genetically improve CWC was through direct selection, however, the premiums for CWC in the Corrledale breed at the time of this study were not sufficient to justify the expected reductions in CFW. The best practical recommendation would be to use the selection index (I₃) with CFW restriction in order to improve clean wool colour without having economic losses. In Experiment 3 an Australian Merino flock was screened for low (resistant) and high (susceptible) YPC breeding values in order to compare extreme individuals using the differential display of mRNA technique. One differentially expressed cDNA band was visualised only in the resistant group and another was present only in the susceptible group. These bands showed no identity with the DNA sequences of public databases, however they showed short homologies with a number of database sequences. The use of these candidate genes as DNA markers need to be confirmed against sheep with a wide range of susceptibility to wool yellowing to verify the results. The fact that the candidate genes for YPC resistance and susceptibility were present in 4 and 3 individuals out of 5, respectively, indicates that there would be some animals that will not have their genotypes identified and more studies are needed to establish more reliable markers and screening criteria

ESTUDO DAS CORRELAÇÕES ENTRE COLORAÇÃO DA LÃ LAVADA (Y-Z) E CARACTERÍSTICAS DA SUARDA

Amostras de lã de várias regiões do velo (lombo, paleta, costilhar e quarto) de borregas Ideal e Corriedale foram analisadas com o objetivo de observar dentro de qual metodologia de análise da suarda as características apresentavam melhores coeficientes de correlação com coloração da lã. Os métodos testados foram: extração da cera em primeiro lugar (método Cera + Suor) e extração do suor em primeiro (método Suor + Cera). Os coeficientes de correlação entre as variáveis pH, cor, absorbância e percentagem de suor e porcentagem de cera com brilho e grau de amarelamento da lã mostraram-se superiores no método Cera + Suor (P < 0,01) nas duas raças. Os coeficientes para a raça Corriedale apresentaram valores inferiores aos obtidos com a raça Ideal. As características de pH, cor e absorbância de suor mostraram uma correlação mais estreita com o grau de amarelamento do que a porcentagem do suor em si (r = 0,62; 0,50; 0,61 vs. 0,36, no método Cera + Suor, para a raça Ideal). A porcentagem de cera apresentou um coeficiente de correlação médio com o grau de amarelamento, significativo somente para Ideal, e de valor negativo. Através da análise de regressão múltipla observou-se que a cor e absorbância do suor e a relação cera/suor determinaram 36% das modificações ocorridas em Y-Z

CARACTERÍSTICAS DA SUARDA E COLORAÇÃO DA LÃ LAVADA EM DIFERENTES REGIÕES DO VELO EM FUNÇÃO DO MEIO AMBIENTE

RESUMO Amostras de lã de quatro regiões do velo (lombo, paleta, quarto e costilhar) de 20 borregas Ideal foram analisadas quanto às percentagens de cera e suor, características do suor (pH, cor e absorbância) e coloração e brilho da lã. Os animais foram mantidos inicialmente a campo (tempo = antes) e posteriormente, por um período de três meses, foram criados sob confinamento em cabanha (tempo = depois). Os resultados demonstraram que as regiões do velo diferem entre si nas características mensuradas, tanto no tempo antes como depois. A amostra do lombo apresentou porcentagem de cera (P < 0,08) superiores às da paleta. A porcentagem de suor não diferiu significativamente (P > 0,05) entre as mesmas. O pH do suor foi significativamente mais ácido (P < 0,001) na região do lombo enquanto os animais permaneciam a campo. A coloração da lã lavada diferiu novamente entre o lombo (mais branca) e a paleta, sendo que o costilhar e o quarto mostraram colorações intermediárias. Não se observou perdas de cera quando os animais permaneceram a campo. A produção de suor diferenciou entre os tempos, contudo, o lombo normalmente tendeu a produzir menos suor (P > 0,05)

EFEITO DA ALIMENTAÇÃO COM CAROTENÓIDES NA COLORAÇÃO DA LÃ LAVADA, l - BORREGAS CORRIEDALE

RESUMO Quarenta borregas corriedale mantidas sob condições de cabanha, receberam alimentação diferenciada por um período de três meses. Após o término do mesmo foram retiradas amostras de lã do costilhar, para posterior análises laboratoriais da suarda e coloração da lã. Os tratamentos consistiram de dietas baseadas em: feno de Rhodes (chloris grayana) + grão de sorgo e feno de alfafa (Medicago sativa) + sorgo em grão, sendo as mesmas isoprotéicas e isocalóricas (11% PB e 65% NDT). Para as características que se diferenciaram significativamente entre os tratamentos alimentares a cor do suor foi mais amarela para o grupo da alfafa e o brilho e coloração da amostra da lã limpa foi mais amarelada (Y-Z = -0,006 vs -0,702 do grupo do milho) para o mesmo tratamento. Contudo, visualmente as amostras foram classificadas como brancas (intervalo de -3,00 e 0,00 para Y-Z). Concluiu-se que o feno de alfafa (carotenóide contido: luteína) pode apresentar, em Corriedale, um aumento no amarelamento normal da lã, tendendo a lãs creme

EFEITO DA METODOLOGIA DE ANÁLISE DA SUARDA NAS CARACTERÍSTICAS DO SUOR, PORCENTAGEM DE CERA E COR DA LÃ LAVADA (Y-Z)

Foram analisadas amostras de lã de várias regiões do velo de borregas pertencentes a duas raças (Ideal e Corriedale) seguindo duas seqüências diferentes para as determinações de porcentagem de cera e suor, cor e pH do suor e coloração da lã. No primeiro método extraiu-se inicialmente a cera e depois o suor (Cera + Suor) e no segundo método a ordem inversa (Suor + Cera). As raças diferenciaram-se quanto à tendência dos valores nas características de cor e porcentagem de suor. Diferenças significativas (P < 0,001) foram observadas na porcentagem de cera, sendo que o método de análise que iniciava pela extração da mesma apresentou valores mais elevados, nas duas raças, para esta característica. A porcentagem de suor foi superior (P < 0,005) para o método Suor + Cera apenas para a raça Corriedale. O brilho da amostra diferiu novamente apenas para esta raça, mostrando lãs mais brilhosas para o método Suor + Cera e também uma tendência (P > 0,05) a apresentar um grau de amarelamento inferior. As características mostraram correições médias entre os dois métodos