Protein-rich Feed Research Articles

System for the production of electricity, leaf protein and single cell protein from sugar cane tops and leaves

In this paper a system is discussed whereby fresh cane tops and leaves (CTL), an agricultural waste available abundantly in sugar cane growing countries, are utilized for the production of electricity from the fibrous fraction and leaf protein (LP) and single cell protein (SCP) from the juice fraction. Based on the yield and characteristics of these products determined in lab scale experiments, material balance, energy balance and some economic aspects of the system to handle 90T of fresh CTL per hour are worked out. The analyses reveal that, excluding the energy requirement for internal use, around 95 kWh of exportable electricity, 3.0 kg of LP and 10.8 kg of SCP may be produced from every tonne of CTL at a cost of 6.2, 6.8 and 17.5 US cents per unit quantity of product respectively. The potential of the 2 million tonnes of CTL available in Mauritius annually, if processed in this system, is 190 GWh of electricity (or half of the electricity generated) and 27 600 T of protein rich feed ingredients (or the total amount imported locally).

Utilisation of cane tops and leaves for energy and food — an integrated system

This paper deals with a system of better utilisation of cane tops and leaves (CTL), a biomass resource so far under-utilised in cane sugar growing countries. The possibility of producing three products, electricity, ethanol and leaf protein (LP), is considered. Based on laboratory scale experiments conducted with a view to verifying the technical feasibility, an integrated system for use of the several fractions of CTL is proposed. The material and energy balance of this system reveals that every tonne of CTL has the potential to produce around 100 kWh of electricity, 8·3 litres of ethanol and 3·0 kg of LP; their unit costs of production are 5·7, 27·0 and 6·8 US cents (1980) respectively. In Mauritius, such use of CTL (2 million tonnes annually) could bring about savings of around 25% and 75% in terms of foreign exchange in current import of energy and protein rich feed ingredients respectively.

The in vitro determination of the protein quality of rumen microorganisms of cows on urea-rich feed

The amino acid composition, essential amino acid index (EAA-I), pepsin-pancreatin in vitro digestibility and pepsin-pancreatin-digest-residue-index (PPDR-I) of the rumen bacterial and protozoal protein of cows fed urea and ammonium salts as their sole source of nitrogen (0-cows) or as a partial source (ULP-cows), and of cows on normal protein-rich feed (NorP-cows), were determined. The amino acid compositions of the rumen bacteria showed very slight changes even though the diets were very different. The amino acid compositions of the pure bacterial strains isolated from the rumina differed slightly. The amino acid compositions of the rumen protozoa of the ULP- and NorP-cows differed only with respect to isoleucine and tyrosine. Protozoa could be found only occasionally in the rumen of the 0-cow, there being only two species. Their nutritional significance was obviously very small. When the nutritional quality of the microbial protein was studied on the basis of its amino acid composition it was found that the EAA-I of bacteria did not differ significantly. Neither did the EAA-I of protozoa differ. The pepsin-pancreatin in vitro digestibility of protozoa was higher on all the feeds than that of bacteria. The rumen bacterial in vitro digestibility with 0-cows differed from that of the ULP-samples but not from that of the NorP-samples. The digestibility of single amino acids, With the exception of diaminopimelic acid, glycine and alanine, did not differ from the digestibility of the total amino acids. The much larger number of bacteria in the rumen of 0-cows compared with those of ULP- and NorP-cows compensates in this way for the lower digestibility of bacterial protein in 0-cows. The PPDR-I of both bacteria and protozoa were well correlated with the in vitro digestibility.

Studies on the sulfur metabolism of cows on protein-free and low-protein feed

The influence of purified, protein-free feed with urea and ammonium salts as nitrogen sources (0-feed) and of non-purified, urea-rich, low-protein feeds (ULP-feed) on the sulfur metabolism of cows has been studied by determining the contents of sulfur fractions in faeces, urine, milk, blood and rumen fluid. The sulfur of 0-feed was composed entirely of inorganic sulfate. During balance trials the N:S ratio in the feed varied from 6.1 to 9.5, and the sulfur content from 0.22 to 0.31 % of the dry matter. In every trial (seven with 0-feed and two with ULP-feed), of five or seven days duration, the cows were in high-positive sulfur balance. The 0-cows excreted a greater proportion of their total sulfur output via urine than the ULP-cows. The excretion of inorganic sulfate sulfur, as a proportion of the urinary and faecal sulfur, was greater for 0-cows than for ULP- or NorP-cows (cows on normal, protein-rich feed); the opposite was the case with regard to the excretion of ester sulfate sulfur and neutral sulfur. The sulfur contents of milk and blood showed only minor inter-feed differences. The sulfate content in the rumen fluid of the 0-cow rose rapidly after the commencement of feeding and then fell quite rapidly. We conclude tentatively that in the rumen of the 0-cow hydrogen sulfide is generated so quickly that the whole of it cannot be used for the synthesis of sulfur-containing compounds, a considerable proportion of it being lost in eructations or excreted as inorganic sulfates in the urine.