From Mendel laws to whole genetic association study to decipher the swine mulefoot phenotype.

The swine mulefoot (SM) is a rare condition characterized by a non-cloven hoof due to the partial or total fusion of the phalanges. No comprehensive study has been conducted to identify associated markers with this phenotype until now. We aimed to characterize the association between SNP and the mulefoot phenotype using a Genome-Wide Association Study (GWAS). An experimental population was produced using a half-sib mating where the male had the mulefoot phenotype and the females (n = 6) had cloven hoofs. The cross resulted in 27 (47%) animals with the mulefoot characteristic and 30 (53%) normal animals, indicating the possible dominant gene action. Animals were further genotyped using the Illumina PorcineSNP50k BeadChip, and SNPs were tested for associations. Twenty-nine SNPs located on the SSC15, SSC4, and SSCX were associated with the mulefoot phenotype (p-value <5 × 10-5). Six markers were found in the intronic regions of VWC2L, CATIP, PDK3, PCYT1B, and POLA1 genes. The marker rs81277626, on SSC15:116,886,110 bp, is located in the Von Willebrand Factor C Domain (VWC2L), a possible functional candidate gene. The VWC2L is part of a biological process involved with the bone morphogenetic protein (BMP) signaling pathway, previously associated with syndactyly in other species. In conclusion, the identified markers suggest the involvement of the VWC2L gene in the SM phenotype in this population.

Correction of INRAPORC® prediction errors for a commercial pig system / Correção de erros de predição do INRAPORC ® para um sistema comercial de suínos

ABSTRACT: INRAPORC® is a mechanistic, dynamic, and deterministic model system that is used in commercial pig production. However, its use is limited as it requires performance information for animals under ad libitum (AL) feed management, which is not provided at all stages of production. Verification of the INRAPORC® calibrations were conducted in this investigation using data from a small group of animals fed with AL in a laboratory situation, to simulate the mean kinetics of a larger commercial population and generate the correction equations for the predicted body weight (BW), and backfat thickness (BT). Analyses were performed by comparing the predicted and observed data, and by submitting them to prediction calibration curve tests (b0 = 0, and b1 = 1). The obtained curves presented a systematic, fixed effect error (+2.37 mm) for BT. The predicted BW and BT values were corrected using the values of the systematic errors obtained. As a result, 100% of the BW averages observed were contained in the confidence intervals (CI) of the INRAPORC® predicted averages, without the need for corrections, and 78.5% of the actual BT averages were contained in the CI of the averages predicted by the system, after corrections. The INRAPORC® calibrations, based on a small population of animals in laboratory conditions could thus be utilized to make predictions for commercial pig production systems and for value correction procedures for the BW and BT of pig populations that have systematic errors in their prediction validations.

RESUMO: O INRAPORC® é um sistema de modelos mecanicista, dinâmico e determinista. Seu uso em sistemas comerciais de produção de suínos é restrito, pois necessita de informações de desempenho de animais sob manejo alimentar à vontade (AV), uma vez que este manejo não é utilizado em todas as fases de produção. Por isso é interessante verificar se a calibração do INRAPORC® baseada em um pequeno grupo de animais AV em situação laboratorial é capaz de simular a cinética média de uma população comercial maior e de subsidiar equações de correção de dados preditos de peso vivo (PV) e espessura de toucinho (ET). As análises foram realizadas comparando os dados preditos e observados sob o teste da curva de calibração da predição (b0=0 e b1=1), as curvas obtidas apresentaram erro sistemático de efeito fixo para a ET de +2,37mm. Os valores preditos de PV e ET foram corrigidos utilizando os valores dos erros sistemáticos obtidos. Como resultado, 100% das médias observadas de PV, estavam contidas nos intervalos de confiança (IC) das médias preditas pelo INRAPORC®, sem necessidade de correções e 78,5% das médias reais de ET estavam contidas nos IC das médias preditas pelo sistema, após as correções. A calibração do INRAPORC® baseada em uma pequena população de animais em situação laboratorial pode ser aplicada para predições de um sistema comercial de criação de suínos, bem como a aplicação do procedimento de correção dos dados preditos de PV e ET nas populações suínas que apresentem erros sistemáticos nas validações preditivas do sistema.

Avaliação de modelos para predição da energia metabolizável do milho para aves / Evaluation of models to predict metabolizable energy of corn for chickens

O estudo foi realizado com o objetivo de avaliar modelos de predição do valor de energia metabolizável aparente corrigida (EMAn) do milho para aves. Foi organizado um banco de dados contendo informações de experimentos, publicados na literatura nacional entre os anos de 1994 a 2007. Foram utilizados dados de composição química, valores de energia bruta e EMAn de 97 amostras de milho, provenientes de estudos em que os valores de EMAn foram determinados pelo método tradicional de coleta total de excretas com pintos de linhagem de corte. Avaliaram-se cinco modelos, sendo quatro deles sugeridos para estimar a EMAn do milho e um para estimar EMAn de alimentos energéticos. Os modelos estudados foram: EMAnC1 = 36,21*PB + 85,37*EE + 37,26*ENN; EMAnC2 = 37,50*PB + 85,37*EE + 38,21*ENN; EMAnC3 = 4021,8 - 227,5*MM; EMAnC4 = 4337,27 - 57,17*FDN; e EMAnC5 = 4371,18 - 26,48*PB + 30,65*EE - 126,93*MM - 52,26*FB - 25,14*FDN + 24,40*FDA. Os valores de EMAn estimados pelos modelos foram comparados com os valores observados utilizando-se a análise de regressão. Em todos os modelos avaliados, houve rejeição (P<0,001) da hipótese de nulidade, demonstrando diferenças entre os valores de EMAn observados e calculados. No desdobramento do quadrado médio do erro de predição (MSD) em seus componentes, constatou-se que os dados simulados pelos modelos EMAnC1, EMAnC3 e EMAnC5 apresentam desvios de magnitude e padrão de flutuação em relação aos dados observados. Por outro lado, verificou-se que as estimativas realizadas com os modelos EMAnC2 e EMAnC4 tiveram predomínio do componente que expressa o vício de predição, indicando o viés constante observado na relação entre os valores observados e preditos. Concluiu-se que nenhum dos cinco modelos estudados permitiu estimar com precisão e acurácia os valores de energia metabolizável aparente corrigida do milho para aves.

A study was realized to validate models to predict apparent metabolizable energy (AMEn) of corn used in chickens diets. Data set with informations of experiments published in national literature among 1994 to 2007 was organized. Chemical composition, gross energy and AMEn of 97 corn samples were including in data set. Studies which AMEn was determined by the traditional method of excreta collection with growing chickens were selected. Five models were evaluates, being four recommended for application in corn and one for application in energetic feedstuffs. The models studied were AMEnC1=36.21*CP + 85.37*EE + 37.26*NNE; AMEnC2 =37.5*CP + 85.37*EE + 38.21*NNE; AMEnC3 =4021.8 - 227.5*ASH; AMEnC4 =4337.27 - 57.17*NDF; e AMEnC5 =4371.18 - 26.48*CP + 30.65*EE - 126.93*ASH - 52.26*CF - 25.14*NDF + 24.40*ADF. The values of AMEn obtained for the models were compared with the observed values using regression analysis. In all the evaluated models there is rejection of the nullity hypothesis, showing differences between estimated and calculated AMEn values. Decomposition of mean squared deviation (MSD) has been demonstrated that calculated values from models AMEnC1, AMEnC3 and AMEnC5 showed that its models failed to simulate the magnitude and pattern of fluctuation. On the other hand, the estimates made with models AMEnC2 e AMEnC4 showed predominance of component bias of prediction that indicates the models failed to simulate the variability of the data around the mean. Energy values predicted using differents models were compared with calculated values by regression analysis. In conclusion any of five models studied allow estimating precisely the apparent metabolizable energy of corn to chickens.

Effects of bermuda grass (Cynodon dactylon cv. Coast cross) and rice hulls on growth performance of 30 day-old weaned rabbits

Several studies have demonstrated that rabbits can be maintained on diets containing high levels of Crude Fiber (CF) when compared to other monogastric animals. In the present study, we examined the effects of rice hulls and of bermuda grass (cv. Coast cross) on the growing performance of 30 day-old weaned rabbits. Rabbits were fed one of 5 diets containing rice hulls and/or bermuda grass as fiber source at the following proportions (BG/RH) 0/17.5, 15/11, 0/29, 14.7/19.1 and 48.5/0 for diets A, B, C, D and E, respectively. Body weight gain and voluntary feed intake were measured at 30, 44, 58 and 72 days. The time necessary to attain 2 kg of live body weight was not affected by the diets. However, daily weight gain differed significantly during the first two weeks after weaning among dietary groups. Diets C and D caused a lower body weight gain, probably because of the high level of Acid Detergent Fiber (ADF) in the diet (24 and 23). Voluntary feed intake increased with age in all treatments, but food intake was lower in treatments C and D when compared to animals receiving treatments B and E. The present results demonstrate that when rice hulls are used as fiber source, fiber must be given as ADF and not as CF because the difference between ADF and CF is enormous. Rice hull-containing diets balanced with CF give an inappropriate amount of components that seem to affect the growth performance of young animals.