Structural equation models for slaughtering weight prediction for broilers.

The aim of this research was to determine the effect of gut health parameters on the flock's final weight of broilers and to calculate an accurate equation to estimate this weight with information available at 7, 14, and 21 days, in field conditions. Gut health parameters (gizzard erosion, coccidiosis, feed passage, and redness, gut tone, consistency of content, and presence of mucus for each part of the small intestine [duodenum, jejunum, and ileum], and color, consistency, and presence of gas for caeca content) were evaluated at 7 and 14 days. Other parameters evaluated for impact on flock final weight were body weight and mortality, both at 7, 14, and 21 days; stocking density; litter reuse; and downtime period. Structural equation model evaluation of the data showed that stocking density and litter reuse did not affect (P > 0.05) flock final weight, while downtime period, body weight (14 and 21 days), and mortality (14 and 21 days) directly affected (P ≤ 0.05) the flock final weight. Gut health parameters did not directly affect the flock's final weight; however, they affected body weight and mortality at 14 days, thus showing an indirect effect on the flock's final weight. It was also possible to determine two accurate equations to estimate the flock's final weight using information available at both 14 (R2 = 0.56) and 21 (R2 = 0.77) days.

Comparison of the efficiency between two sampling plans for aflatoxins analysis in maize.

Variance and performance of two sampling plans for aflatoxins quantification in maize were evaluated. Eight lots of maize were sampled using two plans: manual, using sampling spear for kernels; and automatic, using a continuous flow to collect milled maize. Total variance and sampling, preparation, and analysis variance were determined and compared between plans through multifactor analysis of variance. Four theoretical distribution models were used to compare aflatoxins quantification distributions in eight maize lots. The acceptance and rejection probabilities for a lot under certain aflatoxin concentration were determined using variance and the information on the selected distribution model to build the operational characteristic curves (OC). Sampling and total variance were lower at the automatic plan. The OC curve from the automatic plan reduced both consumer and producer risks in comparison to the manual plan. The automatic plan is more efficient than the manual one because it expresses more accurately the real aflatoxin contamination in maize.

Comparison of the efficiency between two sampling plans for aflatoxins analysis in maize

Variance and performance of two sampling plans for aflatoxins quantification in maize were evaluated. Eight lots of maize were sampled using two plans: manual, using sampling spear for kernels; and automatic, using a continuous flow to collect milled maize. Total variance and sampling, preparation, and analysis variance were determined and compared between plans through multifactor analysis of variance. Four theoretical distribution models were used to compare aflatoxins quantification distributions in eight maize lots. The acceptance and rejection probabilities for a lot under certain aflatoxin concentration were determined using variance and the information on the selected distribution model to build the operational characteristic curves (OC). Sampling and total variance were lower at the automatic plan. The OC curve from the automatic plan reduced both consumer and producer risks in comparison to the manual plan. The automatic plan is more efficient than the manual one because it expresses more accurately the real aflatoxin contamination in maize.

Dois planos de amostragem para análise de fumonisinas em milho / Two sampling plans for fumonisins analysis in maize

O objetivo deste trabalho foi avaliar a eficiência de dois planos de amostragem para análise de fumonisinas (B1+B2) em 11 lotes de milho. Empregaram-se o plano de amostragem manual em grãos inteiros, através do calador graneleiro e o plano de Amostragem Automático em Fluxo Contínuo em grãos moídos (AAFC). Para a comparação dos dois planos de amostragem, foram utilizadas duas medidas de dispersão: a variância e o coeficiente de variação. Em cada plano de amostragem, foram determinadas as variâncias associadas às três etapas do procedimento de detecção das fumonisinas (amostragem, preparação da amostra e análise) e os coeficientes de variação total. A correlação entre as médias de concentrações de fumonisinas e as variâncias de cada etapa do procedimento de detecção foi avaliada para cada plano amostral através da análise de regressão. Na AAFC de milho moído para análise de fumonisinas, obtiveram-se resultados inferiores (P<0,01) de variância na etapa de amostragem (0,0226mg kg-1)², assim como no coeficiente de variação total (6,37%), quando comparados com a variância da amostragem manual (0,0685mg kg-1)² e coeficiente de variação total do plano de amostragem manual em grãos inteiros (8,94%), apresentando, portanto, maior eficiência na detecção de fumonisinas em milho.

The aim of this research was to evaluate the efficiency of two sampling plans for fumonisins (B1+B2) analysis in 11 lots of maize. For sample collection the two systems used were a manual system in whole grains, using sampling spear, and an automatic system in milled grains, using the continuous flow sampling system (CFSS). For comparison purpose, two dispersion measurements were used: variance and coefficient of variation. For each sampling plan the variance associated to the three steps of fumonisins quantification (sampling, sample preparation, and analysis), and the total coefficient of variation were determined. The correlation between the average fumonisins concentration and the variances for each phase of the detection procedure was evaluated for each sampling plan using analysis of regression. At the automatic sampling plan in milled grains for fumonisins analysis in maize both sampling variance (0.0226mg kg-1)² and total coefficient of variation (6.37%) were lower (P<0.01) than in the manual sampling plan in whole grains whit (0.0685mg kg-1)² of variance and 8.94% of coefficient of variation, showing so better efficiency for fumonisin detection on maize.

Desempenho e plumagem de frangos de corte intoxicados por aflatoxinas / Performance and plumage of broiler chicken intoxicated by aflatoxins

O objetivo desta pesquisa foi estudar os efeitos das aflatoxinas sobre o desempenho e plumagem de frangos de corte. Foram utilizados 240 pintos machos, alimentados de 1 a 42 dias de idade com racão ad libitum sem aflatoxinas (grupo controle) e contaminada com 3mg de aflatoxinas/kg de racão (grupo tratado). As aves foram analisadas duas vezes ao dia em relacão ao seu desenvolvimento. O consumo de racão e peso dos animais foram avaliados ao final de cada fase de criacão (21, 35 e 42 dias). Ao final do experimento, realizaram-se as avaliacões patológicas, a pesagem das penas e a avaliacão dos seus aminoácidos. As aves do grupo tratado apresentaram sinais caracteristicos de intoxicacão por aflatoxinas, como desuniformidade da estatura, reducão no consumo de racão e ganho de peso e alteracões microscópicas e macroscópicas em órgãos e tecidos. Observou-se que o coracão e o fígado das aves intoxicadas apresentaram um incremento significativo no peso médio relativo, a massa de penas foi reduzida significativamente (33,8 por cento) e não houve alteracões na concentracão e na composicão dos aminoácidos, apesar do baixo desempenho dos animais intoxicados.