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A series of investigations were undertaken in vitro and in vivo to investigate the nutritive value of cottonseed (WCS), the rumen microbial degradation of oilseeds and legume seeds, and the effects of gossypol on the rumen microbial (bacterial, protozoal and fungal) fermentation, and on the growth of animal cells in culture. An HPLC (High Performance Liquid Chromatography) method for the analysis of gossypol in WCS and in rumen liquor of sheep fed with WCS was also studied. Six oilseeds namely WCS (Gossypium sp.), mustard seed (Brassica sp.) (cv. Albatross), linseed (Linum sp.) (cv. Antares) and three cultivars of rape seeds (Brassica spp.) (cv. Bienvenu, cv. Libravo and cv. Samourai) were incubated with rumen contents in consecutive batch culture (CBC) and examined for their microbial dry matter (DM) degradation. For comparison, another selection of legume seeds namely narbon seed (Vicia narbonensis), mungbean seed (Phaseolus aureus) (cv. Satin), two cultivars of cowpeas (Vigna unguiculata) (cv. Banjo and cv. Caloona), and lablab seed (Lablab purpureus) (cv. Highworth) were also examined for their DM degradation. The oilseeds tended to show lower DM losses, gas production and volatile fatty acids (VFA) concentration than the legume seeds. It is uncertain whether the presence of fat, fractions within fibre such as xylose and lignin, and/or antinutrients such as gossypol in WCS and glucosinolates in rape seeds might contribute to the low fermentation. Although legume seeds are known to contain many antinutrients such as tannins, lectins, protease inhibitors and cyanogenic glycosides, they appeared more readily fermentable than the oilseeds. The overall results suggest that gossypol would affect the numbers of rumen protozoa and fungi, but gossypol was not the only factor and probably not even a major factor influencing the nutritive value of whole cottonseed. In particular much more detailed analysis on the plant cell wall structures such as the proportions of different sugars, and the amounts of lignin-carbohydrate complexes present would need to be performed to determine whether such factors might limit the degradability and fermentability of whole cottonseed. There is also possibility that antinutrients other than gossypol such as pigments tannins and flavanoids may also affect the rumen ecosystem.

Experiments were conducted to investigate the comparative effects of the nitrogen sources, poultry waste, urea or casein/fish meal on the microbial fermentation of carbohydrates in vitro and on in vivo glucose metabolism in sheep. In vitro studies An artificial rumen designed by Czerkawski and Breckenridge (1969) was used in the present study. A series of short term incubations were carried out in which starch or cellulose was incubated with casein, urea, poultry waste or casein + urea. These food combinations were isonitrogenous and had identical dry matter contents. An additional treatment containing grass cubes, hay and poultry waste was also studied. Control incubations were carried out in parallel with all treatment incubations. Nutrients used in control incubations were grass cubes and hay. The duration of each incubation was 61/2h. Fermentation parameters studied were, rate of gas production, pH, and concentrations of volatile fatty acids and ammonia. The fermentation of poultry waste with either of the carbohydrate sources gave rise to a higher volume of gas production than either casein or urea. Urea resulted in a reduction in the volume of gas in the incubation vessels and caused a much larger increase in pH of the incubation medium than did poultry waste. Using mixtures based on starch, the total gas produced in the medium containing poultry waste after 60 and 390 min. of incubation was 44% and 100% greater respectively than that produced from the medium containing casein. Similarly when poultry waste was fermented with cellulose, the total gas production after 60 and 390 min. was 59% and 108% greater respectively than that produced from the fermentation of cellulose + casein. The differences in gas production between urea and poultry waste or urea and casein were not quantified since urea resulted in a reduction in the volume of gas produced. From the starch and cellulose based diets, VFA production in the presence of poultry waste was greater than that from either casein or urea. At the end of incubation, production of VFA from the fermentation of starch + poultry waste was 1.5 or 3.5 times greater than that from starch + casein or starch + urea respectively. Similarly, for a mixture containing cellulose, VFA production in the presence of poultry waste was 2.3 or 6 times higher than that derived from casein or urea respectively. With both starch and cellulose, poultry waste maintained much lower concentrations of ammonia and much lower levels of pH than did urea but considerably higher than those observed with casein. Incubation of grass cubes and hay with poultry waste resulted in greater production of gas and VFA than that obtained from the controls (grass cubes and hay). In vivo studies The primed-continuous infusion technique of Steele et al. (1956) was used to study the comparative effects of poultry waste, urea or fish meal on glucose metabolism with 3 sheep using a 3 x 3 Latin square design. The animals were frequently fed during the experimental period and were maintained on medium quality high roughage diets. Although there were no significant changes in blood glucose level in sheep receiving different nitrogen supplements, the urea and poultry waste containing diets showed a tendency to give lower values than did the fish meal diet. Similarly overall mean insulin concentrations tended to be higher for the fish meal diet than those for the poultry waste or urea diet. Plasma levels of free fatty acid showed small differences between diets which were not significant. Irreversible loss of glucose, glucose pool size, glucose space were estimated. In three out of nine infusions plateau specific activity of glucose was achieved. Consequently, these parameters were calculated for two animals only on each of the dietary treatments. When a plateau glucose specific activity was not attained, the animals exhibited irregular feeding behaviour after about 3h. of infusion and blood analysis showed that they had unusually high levels of cortisol. Plasma glucose concentrations of these animals throughout the infusion period, varied considerably. It appears that uneven feeding behaviour resulted in large fluctuations in the plasma glucose concentrations and specific activity. The results of the in vitro study indicated that poultry waste is more efficient in promoting the utilization of both starch and cellulose than either urea or casein. Poultry waste also caused an improvement in the overall digestion of natural roughage feeds. It was not possible to draw firm conclusion on the results of in vivo experiments because, of the variable data. No significant differences were observed in the concentrations of plasma glucose, insulin, urea or free fatty acids between dietary treatments of fish meal, urea or poultry waste.

Typescript, etc. / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries