Jasna Stekar

Rumen degradation characteristics and fibre composition of various morphological parts of different maize hybrids and possible consequences for breeding

Abstract The rumen dry matter degradability (DMD) of different morphological parts of eight maize hybrids was studied to assess the suitability of nylon bag technique for selecting hybrids for maize silage production. DMD was measured by incubating samples in nylon bags in three rumen fistulated sheep for 6, 12, 18, 24, 48 or 72 h. The data were fitted to the equation p = a + b(1 − e−ct) and effective dry matter degradabilities (EDMD) were calculated using a theoretical rumen outflow rate of k = 0.05 h−1. DMD of all morphological parts varied significantly (P 0.05). Using multiple regression analysis, 0.99 of the variability in EDMD of stover was explained by the concentration of detergent fibres, particularly by the acid detergent fibre (ADF). It was concluded that nylon bag degradability or concentration of fibre components may be used to assess differences in nutritive value between maize hybrids.

Simultaneous determination of iodine and selenium in biological samples by radiochemical neutron activation analysis

SummaryRegarding the favourably sensitive nuclear characteristics of iodine and of selenium but the very different half lives of their induced nuclides 128I and 75Se, a radiochemical neutron activation analysis method for simultaneous determination of these elements in a single sample was developed. It is based on the double irradiation LICSIR technique — Long Irradiation for Se (40h), Cooling (a week or more), Short Irradiation for iodine (1–15 min) with following Radiochemistry. After the second short irradiation, the sample is ignited in an oxygen flask and iodine and selenium are sequentially and selectively extracted as elemental iodine and 5-nitro-2,1,3 benzoselena diazole chelate. With the described method biological samples were analysed and the reliability of the results was checked by the analyses of different standard reference materials. Good agreement with certified values and high radiochemical purity of the spectra show the applicability of the radiochemical separation developed.

Determination of trace amounts of selenium in poultry feedstuffs by gas chromatography

In view of the importance of establishing reliable selenium concentration levels in different kinds of feedstuffs, the purpose of this work was to develop optimum experimental conditions for the isolation and GC determination of selenium as its chelate with 4-nitro-1,2-diaminobenzene. It was shown that ignition of the sample in an oxygen flask followed by reduction of Se(VI) to Se(IV) and the formation of 5-nitro-2,1,3-benzoselenadiazole chelate in HCl medium is a relatively rapid procedure giving a low blank value and allowing the determination of selenium in commercial feedstuffs and similar biological samples. The method was validated by the analysis of suitable certified or standard reference materials.

Differential Effects of Cooked Common Bean (Phaseolus vulgaris) and Lentil (Lens esculenta puyensis) Feeding on Protein and Nucleic Acid Contents in Intestines, Liver and Muscles in Rats

Aim: Our aim was to investigate the influence of legume feeding on the protein and nucleic acid content of intestinal tissues and muscles. Methods: Growing male Wistar rats were fed ad libitum on balanced diets containing cooked common bean or lentil as the unique protein source (180 g·kg–1 dry matter) for 20 days. The control group was pair-fed with an iso-energetic, iso-nitrogenous balanced casein diet. Results: Intestinal tissues were heavier in the legume-fed groups and higher relative mass (g per 100 g body mass) of protein, RNA and DNA were found in these tissues as compared to those of the control groups. In liver protein and RNA masses were significantly lower in the bean group than in the control group but the DNA content was not different in the legume and in the control groups. In gastrocnemius and soleus muscles, there was no significant effect of legume feeding on the fresh mass and on the protein and RNA contents, but the DNA content of the m. gastrocnemius was significantly lower in both legume groups than in their control group. The ribosomal capacity of intestines, liver and muscles was not significantly affected by legume feeding. Conclusion: Legume feeding had a trophic effect on both proximal and distal intestinal tissues; dietary fiber appears to be the main cause of this effect.

Differential Effects of Cooked Beans and Cooked Lentils on Protein Metabolism in Intestine and Muscle in Growing Rats

Aims: The effect of diets based on cooked beans or lentils on protein metabolism in intestines and muscles was studied in rats. Method: The cooked seeds were used as the unique protein source in balanced diets (containing 229 and 190 g of crude protein per kg dry matter) fed to young growing rats for 20 days. Their effects were compared with those of the control casein diet in pair-fed rats. Protein synthesis rates in small and large intestines and in gastrocnemius and soleus muscles were determined in vivo, in a fed state, by the flooding dose method, using 13C-valine. Results: In the small and large intestine tissues of the legume fed groups, protein, RNA relative masses (mg·100 g BM–1) and protein synthesis rates (FSR and ASR) were higher than in the control rats (p < 0.05). In gastrocnemius and soleus muscles,protein and RNA contents (in mg) and protein synthesis rates were significantly (p < 0.05) lower in the legume-fed groups than in the control rats. Conclusion: The chronic intake of cooked legumes increased protein synthesis rates in intestinal tissues and decreased them in muscles. This effect was greater for beans than for lentils in the large intestine and in gastrocnemius muscle.