Meeting Report: Batch-to-Batch Variability in Estrogenic Activity in Commercial Animal Diets—Importance and Approaches for Laboratory Animal Research

We report information from two workshops sponsored by the National Institutes of Health that were held to a) assess whether dietary estrogens could significantly impact end points in experimental animals, and b) involve program participants and feed manufacturers to address the problems associated with measuring and eliminating batch-to-batch variability in rodent diets that may lead to conflicting findings in animal experiments within and between laboratories. Data were presented at the workshops showing that there is significant batch-to-batch variability in estrogenic content of commercial animal diets, and that this variability results in differences in experimental outcomes. A combination of methods were proposed to determine levels of total estrogenic activity and levels of specific estrogenic constituents in soy-containing, casein-containing, and other soy-free rodent diets. Workshop participants recommended that researchers pay greater attention to the type of diet being used in animal studies and choose a diet whose estrogenic activity (or lack thereof) is appropriate for the experimental model and end points of interest. Information about levels of specific phytoestrogens, as well as estrogenic activity caused by other contaminants and measured by bioassay, should be disclosed in scientific publications. This will require laboratory animal diet manufacturers to provide investigators with information regarding the phytoestrogen content and other estrogenic compounds in commercial diets used in animal research

Avaliação de Períodos de Coleta Total de Fezes para Determinar a Digestibilidade Aparente dos Nutrientes em Eqüinos Valuation of Fecal Total Collection Period to Determinate the Apparent Digestibility of Nutrients in Equine

Foram conduzidos dois ensaios de digestão, objetivando comparar os valores de digestibilidade dos nutrientes da cana-de-açúcar e cana-de-açúcar mais milho, em diferentes dias de coleta de fezes. Foram utilizados cinco e quatro cavalos adultos sem raça definida no primeiro e segundo ensaios, respectivamente, com idade média de seis anos. Os animais foram distribuídos aleatoriamente em blocos casualizados, em que cada cavalo constituiu o bloco, e os dias de coleta de fezes, os tratamentos. No primeiro ensaio, foi avaliada a digestibilidade da cana-de-açúcar em seis dias de coleta de fezes (2, 3, 4, 5, 6 e 7 dias), e no segundo ensaio, estimou-se a digestibilidade da cana-de-açúcar e milho em cinco dias de coletas de fezes (2, 3, 4, 5 e 6 dias). Não foram verificadas diferenças (P>0,05) entre os dias de coleta de fezes para estimar a digestibilidade dos nutrientes da cana-de-açúcar e cana-de-açúcar mais milho, porém, verificou-se aumento (P<0,05) na digestibilidade da PB da cana-de-açúcar com milho, na coleta de dois dias. Os períodos de coleta total de fezes de dois a sete dias, para ensaios de digestão com eqüinos alimentados apenas com volumosos, e de três a seis dias, para eqüinos submetidos a dietas mistas, mostraram-se bastante precisos. Dessa forma, sugere-se um período de cinco dias como forma de padronização de metodologia em ensaios de digestão com eqüinos.<br>ABSTRACT - Two digestion assays were carried out, with the objective to compare digestibility of sugar cane and sugar cane plus corn nutrients, in different fecal collection days. Five and four adult horses, without a defined breed and averaging 6 years of age, were utilized in assay 1 and 2, respectively. A randomized block design was used, with each horse considered as block and the days of fecal collection as treatments. In assay 1, the digestibility of sugar cane in six days of the fecal collection (days 2, 3, 4, 5, 6 and 7) was evaluated; and in assay 2, the digestibitlity of sugar cane plus corn over five days of fecal collection ( days 2, 3, 4, 5 and 6) was estimated. There were no significance (P>0.05) between days of fecal collection to estimate digestibility of sugar cane and sugar cane plus corn nutrients. However, an increase (P<0.05) in the digestibility of the CP of the sugar cane plus corn, on the second day of collection was observed. The utilization of three to six and two to seven days of total fecal collection in digestion assays which equines, feed with a mixed diet or solely roughage, respectively, was very precise, and a standard five day, period is recomended

Malnutrition Alters the Innate Immune Response and Increases Early Visceralization following Leishmania donovani Infection

Malnutrition is a risk factor for the development of visceral leishmaniasis. However, the immunological basis for this susceptibility is unknown. We have developed a mouse model to study the effect of malnutrition on innate immunity and early visceralization following Leishmania donovani infection. Three deficient diets were studied, including 6, 3, or 1% protein; these diets were also deficient in iron, zinc, and calories. The control diet contained 17% protein, was zinc and iron sufficient, and was provided ab libitum. Three days after infection with L. donovani promastigotes, the total extradermal (lymph nodes, liver, and spleen) and skin parasite burdens were equivalent in the malnourished (3% protein) and control mice, but in the malnourished group, a greater percentage (39.8 and 4.0%, respectively; P = 0.009) of the extradermal parasite burden was contained in the spleen and liver. The comparable levels of parasites in the footpads in the two diet groups and the higher lymph node parasite burdens in the well-nourished mice indicated that the higher visceral parasite burdens in the malnourished mice were not due to a deficit in local parasite killing but to a failure of lymph node barrier function. Lymph node cells from the malnourished, infected mice produced increased levels of prostaglandin E(2) (PGE(2)) and decreased levels of interleukin-10. Inducible nitric oxide synthase activity was significantly lower in the spleen and liver of the malnourished mice. Thus, malnutrition causes a failure of lymph node barrier function after L. donovani infection, which may be related to excessive production of PGE(2) and decreased levels of IL-10 and nitric oxide