Methods for the diagnosis of phosphorus deficiency in ruminants

No presente experimento foram comparados níveis de fósforo inorgânico nas fezes, plasma, saliva e líquido do rúmen e a incorporação de 32P pelos eritrócitos, para diagnóstico da deficiência de fósforo em bovinos. Foram utilizados dez animais, mantidos em dieta semipurificada, que receberam, ou não, suplementação de fósforo. Os resultados mostraram que a deficiência de fósforo deprimiu o nível desse elemento no plasma, rúmen e fezes. Dada a grande variação nos resultados do fósforo na saliva, esse parâmetro mostrou não ser adequado para indicar o "status" desse elemento. A incorporação de 32P pelos eritrócitos não apresentou diferenças significativas entre os dois grupos. In the present experiment levels of inorganic phosphorus in feces, plasma, saliva and rumen fluid, and 32P incorporation by erythrocytes were compared as means for phosphorus deficiency diagnosis in cattle. Ten animals receiving a semipurified diet were divided into two groups, receiving or not phosphorus supplementation. In the experiment a variety of methods were used for phosphorus deficiency diagnosis in cattle. The results show that P deficiency depress the level of inorganic phosphorus in plasma, rumen and feces. The uptake of 32P by erythrocytes has some value in the detection of such deficiency.

A new approach for in vitro bioassay to measure tannin biological effects based on a gas production technique

The aim of this paper was to study a method based on gas production technique to measure the biological effects of tannins on rumen fermentation. Six feeds were used as fermentation substrates in a semi-automated gas method: feed A - aroeira (Astronium urundeuva); feed B - jurema preta (Mimosa hostilis), feed C - sorghum grains (Sorghum bicolor); feed D - Tifton-85 (Cynodon sp.); and two others prepared mixing 450 g sorghum leaves, 450 g concentrate (maize and soybean meal) and 100 g either of acacia (Acacia mearnsii) tannin extract (feed E) or quebracho (Schinopsis lorentzii) tannin extract (feed F) per kg (w:w). Three assays were carried out to standardize the bioassay for tannins. The first assay compared two binding agents (polyethylene glycol - PEG - and polyvinyl polypirrolidone - PVPP) to attenuate the tannin effects. The complex formed by PEG and tannins showed to be more stable than PVPP and tannins. Then, in the second assay, PEG was used as binding agent, and this assay was done to evaluate levels of PEG (0, 500, 750, 1000 and 1250 mg/g DM) to minimize the tannin effect. All the tested levels of PEG produced a response to evaluate tannin effects but the best response was for dose of 1000 mg/g DM. Using this dose of PEG, the final assay was carried out to test three compounds (tannic acid, quebracho extract and acacia extract) to establish a curve of biological equivalent effect of tannins. For this, five levels of each compound were added to I g of a standard feed (Lucerne hay). The equivalent effect showed not to be directly related to the chemical analysis for tannins. It was shown that different sources of tannins had different activities or reactivities. The curves of biological equivalence can provide information about tannin reactivity and its use seems to be important as an additional factor for chemical analysis. (C) 2007 Elsevier B.V. All rights reserved