Dual-energy X-ray absorptiometry: an effective approach for predicting broiler chicken body composition

ABSTRACT: Two trials were carried out to develop and validate linear regression equations for body composition prediction using Dual-energy X-ray absorptiometry (DEXA). In Trial 1, 300 Cobb500 male chickens raised from 1 to 42 d of age were scanned in DEXA to estimate total weight, fat mass, soft lean tissue (SLT) mass, bone mineral content (BMC), and fat percentage. DEXA estimates were compared to body ash, crude fat, SLT (sum of protein and water) and scale body weight. The dataset was split, with 70% used for prediction equations development and 30% for testing, and the 5k-fold cross-validation analysis was used to optimize the equations. The R2, mean absolute error (MAE), and root-mean-squared error (RMSE) were used as precision and accuracy indicators. A negative correlation (ρ = ˗0.27) was observed for ash content, while no correlation was observed for protein content (P > 0.05). Predictive linear equations were developed to assess broiler weight (R2 = 0.999, MAE = 25.12, RMSE = 38.99), fat mass (R2 = 0.981, MAE = 13.87, RMSE = 21.28), ash mass (R2 = 0.956, MAE = 3.98, RMSE = 5.61), SLT mass (R2 = 0.997, MAE = 35.73, RMSE = 52.45), water mass (R2 = 0.997, MAE = 29.56, RMSE = 43.94), protein mass (R2 = 0.989, MAE = 12.94, RMSE = 19.05), fat content (R2 = 0.855, MAE = 0.81, RMSE = 1.05), SLT content (R2 = 0.658, MAE = 1.01, RMSE = 1.28), and water content (R2 = 0.678, MAE = 0.99, RMSE = 1.27). All equations passed the test. In Trial 2, 395 Cobb500 male chickens were raised from 1 to 42 d of age and used for validation of prediction equations. The equations developed for weight, fat mass, ash mass, SLT mass, water mass, and protein mass were validated. In conclusion, DEXA was found to be an effective approach for measuring the body composition of broilers when using predictive equations validated in this study for estimate calibration

Myxomycetes occurring on Cecropia adenopus (Cecropiaceae) in fragments of Atlantic Rainforest Myxomycetes ocorrentes em Cecropia adenopus (Cecropiaceae) em fragmentos de Floresta Atlântica

Cecropia adenopus (Ambay pumpwood) is a frequent native species on the edges of woods and clearings and is considered a pioneer species in re-colonized areas. Despite its distribution from Mexico to Argentina, this substrate has never been examined in detail regarding the presence of Myxomycetes. In the present study, the myxobiota associated with leaf debris of C. adenopus was investigated in two Atlantic Rainforest conservation units located in the Brazilian state of Rio Grande do Norte. Five specimens and one plasmodium were obtained directly from the field and 87 were developed in 43.7% of 200 moist-chamber cultures set up separately with blades and petioles. Fifteen species were identified and illustrated. The two predominant groups were representatives of Trichiales and Physarales. Didymium columella-cavum was recorded for the second time in Brazil and in the world.<br>Cecropia adenopus (embaúba) é uma espécie nativa, frequente em bordas de matas e clareiras e tida como espécie pioneira em áreas recolonizadas. Apesar de ocorrer desde o México até a Argentina este substrato nunca tinha sido examinado com detalhe quanto à presença de Myxomycetes. No presente estudo, a mixobiota associada a folhas mortas de C. adenopus foi investigada em duas Unidades de Conservação da Floresta Atlântica, situadas no estado do Rio Grande do Norte. Cinco espécimes e um plasmódio foram obtidos diretamente no campo e 87 desenvolveram-se em 43,7% de 200 câmaras-úmidas, montadas com lâminas foliares e pecíolos separadamente. Quinze espécies de Myxomycetes foram identificadas e ilustradas. Os dois grupos predominantes pertencem às ordens Trichiales e Physarales. Didymium columella-cavum foi encontrado pela segunda vez no Brasil e no mundo