Comparison of factor-analytic and reduced rank models for test-day milk yield in Gyr dairy cattle (Bos indicus)

We analyzed 46,161 monthly test-day records of milk production from 7453 first lactations of crossbred dairy Gyr (Bos indicus) x Holstein cows. The following seven models were compared: standard multivariate model (M10), three reduced rank models fitting the first 2, 3, or 4 genetic principal components, and three models considering a 2-, 3-, or 4-factor structure for the genetic covariance matrix. Full rank residual covariance matrices were considered for all models. The model fitting the first two principal components (PC2) was the best according to the model selection criteria. Similar phenotypic, genetic, and residual variances were obtained with models M10 and PC2. The heritability estimates ranged from 0.14 to 0.21 and from 0.13 to 0.21 for models M10 and PC2, respectively. The genetic correlations obtained with model PC2 were slightly higher than those estimated with model M10. PC2 markedly reduced the number of parameters estimated and the time spent to reach convergence. We concluded that two principal components are sufficient to model the structure of genetic covariances between test-day milk yields. © FUNPEC-RP.

Validity and feasibility of qualitative behavior assessment for the evaluation of Nellore cattle temperament

The aims of this study were to assess the validity and the feasibility of the qualitative behavior assessment (QBA) method as indicator of Nellore cattle temperament under field conditions, evaluating its associations with four other traditional methods and weight gain. The temperament and live weight of 2229 Nellore cattle was assessed at approximately 550 days of age. Five measurements of cattle temperament were recorded: flight speed test (FS, in m/s), visual scores of movement in the crush (MOV), crush score (CS), temperament score (TS), and the qualitative behavior assessment method (QBA), by using a list of 12 behavioral based adjectives as descriptors of temperament. Average daily weight gain (ADG) was calculated for each animal. For statistical analysis of QBA data, the Principal Component Analysis was used. A temperament index (TI) was defined for each animal using the scores for the first principal component. Pearson's correlation coefficients were estimated between TI with FS and ADG. A mixed model ANOVA was used to analyze the TI variation as a function of TS, CS, and MOV. The score plot for the first and second principal components was used to classify the cattle in four groups (from very bad to very good temperament). The first principal component explained 49.50% of the variation in the data set, with higher positive loadings for the adjectives 'agitated' and 'active', and higher negative loadings for 'calm' and 'relaxed'. TI was significantly correlated with FS (r=0.49; P<0.01) and ADG (r=-0.10; P<0.01). The means of ADG, FS, and the temperament scores (CS, TS, MOV) differed significantly (P<0.01) among the four groups, from very bad to very good temperament. The QBA method could discriminate different behavioral profiles of Nellore cattle and were in agreement with other traditional methods used as indicators of cattle temperament. Additional studies are needed to assess the inter- and intra-observers reliability and to study its association with physiological parameters. © 2013 Elsevier B.V.

Resistance of beef cattle of two genetic groups to ectoparasites and gastrointestinal nematodes in the state of São Paulo, Brazil

The resistance to infestations by ectoparasites and infections by gastrointestinal nematodes was studied in 45 animals (males and females) of two genetic groups: purebred Nelore (NI, n=28) and Three-Cross (1/2 Angus+1/4 Canchim+1/4 Nelore - TC, n=17). The animals were monitored for 24months, during which they were left to graze in tropical pastures without receiving treatment for parasites. Each month the animals were examined for infestations by external parasites, to count the numbers of cattle ticks Rhipicephalus microplus with diameter greater than 4.5mm present on the left side, horn flies (Haematobia irritans) present in the lumbar region and botfly larvae (Dermatobia hominis) present on the entire body. The H. irritans counts were performed with the aid of digital photographs. At the time of examination, fecal samples were collected to count the eggs per gram (EPG) and to perform coprocultures, and peripheral blood samples were drawn to determine the packed cell volume (PCV) and to count the eosinophils. For statistical analysis, the count data were transformed into log10 (n+1), where n is the number of parasites. For PCV, significant effects (P<0.05) were found for collection month (CO), genetic group (GG) and gender (SX), with means and respective standard errors of 41.5±0.65% for the NI animals, 39.3±0.83% for the TC, 41.5±0.72% for the females and 39.3±0.77% for the males. Regarding the eosinophil counts, only the effect of sex was significant (P<0.01), with means and respective standard errors of 926.0±46.2/μL, for males and 1088.0±43.8/μL of blood, for females. The NI animals presented lower mean counts for all the external parasites compared to the TC animals (P<0.01). For ticks, the transformed means followed by standard errors for the NI and TC animals were 0.06±0.01 and 0.34±0.02, while for horn flies these were 0.92±0.05 and 1.36±0.06 and for botfly larvae they were 0.05±0.03 and 0.45±0.05, respectively. The average EPG values were only influenced by CO (P<0.01). The coprocultures revealed the presence of the following endoparasites: Haemonchus spp., Cooperia spp., Oesophagostomum spp. and Trichostrongylus spp., the last in smaller proportion. There were no significant differences between the genetic groups for the endoparasite loads, except for Cooperia spp., which were present in greater number (P<0.05) in the NI group. The results obtained in this experiment confirm previous findings of greater susceptibility of the Nelore breed to Cooperia spp. and high resistance to ectoparasites. © 2013 Elsevier B.V.

Carcass characteristics of feedlot lambs fed crude glycerin contaminated with high concentrations of crude fat

Thirty non-castrated male lambs with 20. ±. 2.3. kg average body weight (BW) were randomly assigned to five treatments consisted of different dietary concentrations of crude glycerin (CG; 0, 3, 6, 9 and 12% on DM basis) to evaluate the effects on performance, carcass and meat quality traits. A quadratic effect was observed for performance (P= 0.04), final BW (P<. 0.01) and hot carcass weight (P<. 0.01). No effects of CG were observed (P>. 0.05) on carcass pH neither on shear-force, cooking loss and ether extract content in longissimus. The inclusion of CG tended to reduce the Zn content in meat (P= 0.09). The data suggests that CG (36.2% of glycerol and 46.5% of crude fat) may be used in diets of finishing lambs with concentrations up to 3% without negative effects on performance and main carcass traits. Moreover, inclusion of CG seems to not affect quality and safety of meat for human consumption. © 2013 Elsevier Ltd.

Inclusão de cana-de-açúcar triturada em biodigestores abastecidos com dejetos de bovinos de corte confinados

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Genetic relationship between reproductive traits in Nellore cattle

Pós-graduação em Genética e Melhoramento Animal - FCAV

Estudo de fatores genéticos e de ambiente para reatividade na raça Nelore

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desempenho e características da carcaça e da carne de bovinos de diferentes grupos genéticos

Pós-graduação em Zootecnia - FCAV

Desempenho, características de carcaça e da qualidade da carne de bovinos de corte terminados em confinamento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modelos de análise de dados de provas de ganho em peso de bovinos da raça Nelore

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Marcadores moleculares associados à qualidade de carne em bovinos Nelore

Pós-graduação em Genética e Melhoramento Animal - FCAV

Fatores associados à injúria muscular em bovinos abatidos e suas relações com enzimas séricas e qualidade da carcaça

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ocorrência de Escherichia coli O157:H7 em bovinos abatidos em estabelecimento habilitado à exportação na cidade de Barretos – SP, Brasil

Pós-graduação em Microbiologia Agropecuária - FCAV

Comportamento ingestivo de bovinos Nelore confinados adaptados com diferentes protocolos à dieta de alto concentrado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Técnica dos isótopos estáveis para determinar o turnover de carbono nas fezes, no sangue e plasma de bovinos jovens confinados

Pós-graduação em Zootecnia - FMVZ