No abstract

No abstract

The effect of increasing concentrations of short-chain fatty acids [SCFA; mixture of the Na+ salts of acetic acid (62.5%), propionic acid (25.0%) and of butyric acid (12.5%)] on Na+ transport of sheep rumen epithelium was studied in vitro. The conventional Ussing chamber method was used for measuring Na+ transport rates (22Na+), short-circuit current (Isc) and tissue conductance (GT) of isolated rumen epithelium. SCFA in the buffer solution on the mucosal side caused a linear increase of Jnet Na+ from 1.14, to 1.22, 1.78 and 2.50 microeq/cm2/h in hay-fed sheep at 0, 15, 40 and 80 mmol/l SCFA, respectively. In a second study, the effect of higher SCFA concentrations [0 (control), 80, 100 and 120 mmol/l] was investigated with epithelia from two groups of sheep. One group was subjected to hay ad libitum, whereas the other received concentrate feed (800 g/day in equal portions at 7.00 am and 3.00 pm) and hay ad libitum. Epithelia from concentrate-fed sheep again showed a significant (p < 0.05) and linear increase in Jnet Na+ at 80, 100 and 120 mmol/l. However, in hay-fed sheep, the difference in increase among 80, 100 and 120 mmol/l SCFA was not significant, indicating that, above 80 mmol/l SCFA Jms and Jnet exhibit saturation. Moreover, Na+ fluxes (Jms and Jnet) were generally higher in concentrate-fed than in hay-fed sheep at all SCFA concentrations and significant differences were observed at 100 and 120 mmol/l SCFA. The obtained results confirm the effect of SCFA on Na+ transport and are in agreement with studies regarding feeding regimes and electrolyte transport in the rumen. The important new observation is the increase of Na+ transport in concentrate-fed sheep even at high concentrations of SCFA (100 and 120 mmol/l). The enhanced activity of the Na+/H+ exchanger at these SCFA concentrations supports the assumption that the capacity for regulating the intracellular pH by extrusion of protons is increased, suggesting an adaptation in concentrate-fed sheep. This adaptation could prevent possible disturbances of epithelial functions (transport and barrier) under conditions of increased SCFA absorption.

The aim of the present study was to extract lignin from sugarcane bagasse followed by its structural characterization, oxidation, and evaluation of antioxidant activities. Lignin was extracted in a process involving different concentrations (1, 5, and 10 %) of NaOH solutions. The chemical composition of untreated and treated bagasse samples was analyzed which clearly showed that the delignification was found to be maximum with 10 % NaOH. The scanning electron microscopy (SEM) images of untreated and treated samples of bagasse were taken to study the physical changes occurred in the bagasse during different treatments. Lignin extracted was purified with acidified water and oxidized with 10 % H 2 O 2 . Both lignin and oxidized lignin were structurally characterized using Fourier-transformed infrared (FTIR), 1 H, and 13 C NMR spectra. The antioxidant potential of lignin and its oxidized derivative was evaluated by radical scavenging activity using DPPH method. Lignin was found to have higher antioxidant activity than oxidized lignin. This was attributed to a higher number of phenolic groups in lignin than in oxidized lignin. Both lignin and its oxidized derivative were observed to have higher antioxidant activity than 3,5-di-tert-butyl-4-hydroxytoluene (BHT) and lower than 3-tert-butyl-4-hydroxyanisole (BHA). It was concluded that sugarcane bagasse lignin and its oxidized derivative could be used as potential antioxidant of food oils and fats.

The present in vitro experiment was conducted to study the effect of two concentrations of short chain fatty acids [SCFA: 0 (control), 40 and 100 mmol/l in the buffer solution on mucosal side] on calcium ion (Ca2+) transport across the isolated rumen epithelium of two groups of sheep. One group was subjected to hay ad libitum, whereas the other to concentrate feed (800 g per day in equal portion at 7.00 and 15.00 hours and hay ad lib). The conventional Ussing chamber method was used for measuring the Ca2+ transport rates (45Ca), short-circuit current (Isc) and tissue conductance (GT) of isolated rumen epithelium. The SCFA significantly increased Isc of the epithelia of concentrate-fed sheep. In both hay- and concentrate-fed animals, 45Ca flux rates showed an almost linear increase in net flux rate () with rising concentrations of SCFA, as a result of a combined effect of a large increase in mucosal-to-serosal flux rates () and an almost linear, but small, decrease in serosal-to-mucosal flux rate (). In concentrate-fed sheep and were significantly higher in tissues incubated with SCFA compared with hay-fed animals. The well-known adaptable morphological and functional changes in the rumen epithelium attributable to concentrate feeding obviously include Ca2+ transport; such feeding therefore may be considered as a possible prophylactic measure in the prevention of milk fever.