Correção de medida ultrassonográfica de carcaça em coelhos usando modelo linear misto com covariáveis / Correction ultrasonographic measurement of carcass in rabbits using mixed linear Model with covariates

Objetivou-se avaliar a correção da medida ultrassonográfica da área do músculo Longissimus dorsi, em coelhos da raça Nova Zelândia, pela análise de covariância usando modelos mistos. Foram realizadas análises em delineamento em blocos completos ao acaso, com cinco tratamentos (operadores) e seis blocos (animais), considerando na análise: a inexistência de covariáveis; a covariável comprimento de olho de lombo; a covariável profundidade de olho de lombo; e as duas covariáveis juntas. Como os animais são uma amostra aleatória, o efeito de bloco foi considerado como aleatório. Consideraram-se as covariáveis como medidas com efeito fixo sem erro, independentemente do tratamento e do comportamento linear. As estatísticas de critério de decisão CV%, R ² e R ¯ ² evidenciaram relação direta entre si e podem ser consideradas para avaliar a precisão experimental em ensaios com avaliação de carcaças. Os valores das estatísticas AIC, BIC e AICC apresentam coerência com a interpretação dos critérios de decisão e indicam que o modelo com duas covariáveis proporciona resultados acurados. A inclusão das covariáveis complementa o controle de local com melhoria na precisão do experimento. A utilização das medidas ultrassonográficas de profundidade e comprimento corrige a média da área do músculo Longissimus dorsi avaliado por diferentes operadores.(AU)

The objective of this study was to evaluate the correction ultrasonographic measurement of area the Longissimus dorsi muscle in New Zealand rabbits by covariance analysis using mixed linear models. The analyzes were performed in randomized block design with 5 treatments (operators) and 6 blocks (animals), considering in the analysis: absence of covariates; rib eye length as covariate; rib eye depth as covariate; the two covariates together. As the animals are a random sample, the block effect was considered to be random. The covariates were considered as measures of fixed effect without error, independent of treatment and linear comportment. The decision criterion statistics CV%, R², and R ¯ ²showed a direct relationship between them and can be taken into consideration to evaluate the experimental accuracy in tests with carcass evaluation. The AIC, BIC, and AICC statistics are consistent with the interpretation of the decision criteria and indicate that the two covariates in model provides accurate results. The inclusion of covariates complements the local control to improve the accuracy of the experiment. The use of ultrasound measurements of depth and length corrects the mean area of the Longissimus dorsi muscle evaluated by different operators.(AU)

Effects of cottonseed oil and ferrous sulfate on the performance and expression of antioxidant enzymes in broilers.

Aiming to reduce feed costs, cottonseed oil (CSO) has been used as an alternative component in diets for broilers. However, this oil contains gossypol, an antinutritional agent that impacts the use of mineral elements, inhibits glucose uptake, and has a direct inhibitory action on intestinal enzymes. Nevertheless, toxic effects of gossypol can be prevented by the addition of iron salts, such as ferrous sulfate (FS), to the diet. This work was conducted to evaluate performance and gene expression of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in the intestines of 21- and 42-day-old broilers fed 0, 2, 4, or 6% concentrations of CSO, with or without FS. All CSO diets led to weight gain (WG) at 21 D. At 42 D, an increase in WG and a decrease in feed conversion (FCR) in the diets containing FS were observed. In 21-day-old birds supplemented with 4% CSO and FS, an increase in GPx gene expression was observed when compared to the 6% level. Animals (42 day old) supplemented with 6% CSO and FS presented greater expression of SOD gene when compared to 2% CSO and FS. In addition, a higher GPx expression in broilers supplemented with 6% CSO and FS compared to 6% CSO without FS was achieved. In conclusion, including CSO in the diets of broiler favors WG in animals at 21 D of age, independent of the presence or absence of FS; and including 4% CSO and FS in the diet of these animals alters the expression of the GPx gene in the intestine, so it is not necessary to add FS at 21 D. On the other hand, in 42-day-old broilers, the addition of FS is indicated, due to increases WG, decreased FCR and at the 6% CSO level without FS increase in the expression of the SOD and GPx genes.