published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

The nutritional and chemical characteristics of five earthworm species: Lumbricus terrestris; Allolobophora longa; Eisenia foetida; Dendrobaena veneta and Dendrodrilus subrubicundus were assessed on the basis of crude protein and amino acid composition, lipid and fatty acid composition, and ash and mineral composition. Analyses indicated that all the earthworm species evaluated possessed a high quality protein and lipid fraction suitable for use in fish feeds which was somewhat similar in composition to that of fish meal. During experimental feeding trials (50-84 days in duration) each earthworm species was nutritionally evaluated, on the basis of fish growth performance, feed utilization efficiency and gross carcass composition, as a complete feed (frozen slices of whole worm) for rainbow trout· (Salmo gairdneri) A dried 'earthw9rm meal' derived from each of the species E.foetida, D.veneta and D.subrubicundus was similarly evaluated as a potential replacement for fish meal in trout diets. Fish fed frozen slices of earthworm, with the exception of fish fed E.foetida, achieved growth rates and feed utilization efficiency comparable to. fish fed a control, fish meal based ration. Fish fed solely on frozen slices of E.foetida achieved little or no growth over the experimental period. The possible reasons for the reduced palatability of frozen E.foetida to the fish are discussed, pre-treatment processes applied and a significant improvement in the palatability of frozen E.foetida was achieved by blanching. High dietary inclusion levels of earthworm meal (replacing ~ 50% of the fish meal protein) resulted in depressed feed intake and growth of the fish. At reduced levels of inclusion, dried E.foetida meal (constituting 5-30% of a production salmonid diet) and dried D.subrubicundus meal (constituting 7-36% o~ a semi-synthetic trout diet) adequately replaced the dietary fish meal component without loss in fish growth and feed utilization efficiency. The possible uptake of potentially toxic trace elemeots (Fe, Zn, Mn, Pb, Cu, Cr, Ni, Co and Cd) into the fish carcass through the ingestion of contaminated earthworm diets was also investigated and the levels of certain elements, in particular Pb, were observed to increase in the carcass of fish fed high levels of earthworm in the diet. However, in no instance did the results indicate any harmful or toxic effect of including earthworms in the diets of rainbow trout.

The effects of different dietary lipids on the growth, nutrition and tissue lipid profiles of rainbow trout raised to market size on a commercially available ration were examined. Rainbow trout of 80 g mean initial weight were fed pellets prepared according to Oregon Moist Pellet specifications for 20 weeks. Salmon oil (0MP-1), soybean oil (OMP-2), linseed oil (OMP-3), chicken fat (OMP-4), pork lard (OMP-5) and beef tallow (OMP-6) were used for the 6% lipid component of the diets. No differences in feed conversion or growth rate were observed across diet groups. Trout nutrition was monitored by three blood parameters -- red blood cell (RBC) fragility (hemolysis), packed cell volume (PCV) (hematocrit), and percent hemoglobin. The OMP-1 diet appeared to have caused oxidative stress in trout as measured by hemolysis, while hematocrit and percent hemoglobin values were uniform across diet groups. Tissue levels of total n-3 fatty acids were highest in the OMP-3 group and decreased in the order OMP-1 > OMP-2 = OMP-4 = OMP-5 = OMP-6. However, unaltered linolenic acid (18:3 n-3) comprised almost 50% of the n-3 fatty acid content of OMP-3 trout tissue lipid. The level of total 20:5 n-3 plus 22:6 n-3 (18%), was 33% higher in tissue from OMP-1 trout than tissue from all other diet groups which held fairly constant at 12% across OMP groups 3-6. The lowest tissue level of total 20:5 n-3 plus 22:6 n-3 was found in the OMP-2 trout, 10%. Trout raised on the OMP-1 diet also retained higher tissue stores of 20 and 22 carbon monoenes than trout fed OMP diets 2-6, but less than dietary levels. In contrast, trout fed OMP diets 2-6 retained higher tissue levels of these same fatty acids than dietary levels. The diet ratio of polyunsaturated fatty acids (PUFA)/22:1 appeared to influence whether 22:1 was conserved or oxidized. The most favorable balance of trout tissue monoenes, n-6 fatty acids and total 20:5 n-3 plus 22:6 n-6 for human health was found in trout fed the OMP-6 diet. / Graduation date: 1988

A replicated 3 x 3 latin square design (3 periods and 6 rumen fistulated steers) was utilized to investigate the effect of dietary concentrate levels (30, 60 and 90%) on the in situ disappearance of dry matter (ISDMD) and neutral detergent fiber (NDF) and kinetics of fiber digestion of alfalfa hay, wheat straw and steam processed and flaked milo (SPFM). Concentrate levels of 30 and 60% did not affect (P > .05) ISDMD or NDF disappearance from any of the substrates. However, ISDMD and NDF disappearance of all substrates were depressed (P < .05) by the 90% concentrate diet. The degradation of the potentially digestible fiber in these substrates followed first order kinetics at all concentrate levels. Fiber digestion kinetics were not affected (P > .05) by dietary concentrate levels of 30 or 60%. Incubation of substrates in animals receiving the 90% concentrate diet resulted in lower potential extent of digestion (P > .05) and decreased rate of degradation (P > .05) for all substrates. However, digestion was not complete even after incubations of 168-h, and thus, it is possible that the potential extent of digestion was underestimated. For all substrates lag time of digestion appeared to increase in the 90% concentrate diet. However, influx of NDF-like material into the bag during incubation makes the validity of the lag times obtained in situ questionable. Ruminal pH was depressed in animals consuming the 90% concentrate diet and could be at least one of the factors responsible for the decreased (P > .05) fiber digestibility in this diet. Mean ruminal pH of 6.5 (30 and 60% concentrate diets) did not depress (P > .05) fiber digestibility while a mean pH of 6.2 resulted in a lower (P > .05) fiber digestibility in the rumen.

A series of studies was conducted using SEM in conjunction with chemical analysis, in situ and in vitro digestion techniques, to characterize the anatomical components from barley, corn, sorghum and wheat grains which constitute "fiber" and investigate their susceptibility to rumen microbial digestion. Fractured grains were used to identify anatomical features and cell types prior to and after extraction or digestion. Certain anatomical features, including pericarp tissue, aleurone cells, endosperm cell walls, corneous and floury endosperm tissue and lemma and palea from barley, were easily identifiable in fractured and ground grains, and in neutral detergent extracted or digested residues. In situ and in vitro incubation conditions were varied to assess the effect of concentrate and/or reduction of pH on the disappearance of identifiable grain fractions. In situ incubations were conducted using steers adapted to 0-, 30- and 90% concentrate diets. In vitro inoculum buffered at pH 7 or 6 was provided by a steer fed 0- or 90% concentrate. Tissues resistant to rumen microbial digestion during extended (144-h) in situ incubations and shorter term (12- to 48-h) in vitro incubations were primarily those identified in NDF, and included pericarp, lemma and palea, and small amounts of corneous endosperm. Remaining tissues identified included barley lemma, palea and pericarp; corn pericarp, tip cap and small amounts of corneous endosperm; sorghum pericarp and corneous endosperm with matrix and protein bodies; and wheat pericarp. In vitro disappearance of isolated NDF after 48-h ranged from 43% for barley to 89% for corn. Labile structures included embryonic tissue and portions of endosperm cell walls, protein matrix and residual starch. Resistant tissues included pericarp, aleurone cell walls, tip cap and portions of the corneous endosperm. Relative rankings of NDF digestibility under all conditions studied were similar (corn > sorghum > wheat > barley) whether determined using isolated NDF or calculated from TIVDMD residues. Neither concentrate level fed to the host animal nor pH of the in vitro incubation flask affected rankings among grains, although increasing concentrate level and/or reducing pH appeared to reduce in vitro NDF disappearance. Evaluation of electron micrographs of fractured grains suggested that similar anatomical structures in the various grains differed in their resistance to microbial digestion. For example, pericarp from barley and wheat appeared to be more resistant than that from corn or sorghum. Endosperm of barley was less resistant than that of sorghum.

The occurrence and concentration of substances like glycosides, alkaloids, certain amino acids, and, especially, phenolics in vegetation has been seen as a defense against environmental perturbations. Whether this phenomenon is associated with the disruptive effect of man, herbivore predation or the invasion of arthropods and microorganisms remains to be ascertained by ecologists. However, contemporary research shows that most so-called secondary metabolites in plants render them less sensitive to adverse factors in the natural environment. Likewise, herbivores that adapted to chemical defense in plants were rewarded with wider food source and might have been able to more efficiently exploit rapidly changing foraging environments. This study focuses on relationships between goats, their ruminal microbes and tannin-rich plants in a central Arizona chaparral vegetation type dominated by shrub live oak (Quercus turbinella). The study tested hypotheses involving goat dietary selection, estimated through microhistological analysis of feces; phenolic profile of shrub live oak, expressed as condensed and hydrolyzable tannins, protein binding capacity of oak leaves extract, expressed as bovine serum albumin (BSA) precipitation; and apparent dry matter digestibility of mature and immature oak leaves by goat ruminal microbes measured at 6, 12, 24 and 48 hours. Findings of this research indicated that goats prefer leaf and shoot ends of shrubs, mainly shrub live oak, despite the constant high concentration of tannins in that plant. Hydrolyzable tannins in oak are synthesized during summer/fall and late spring, and the synthesis of condensed tannins is mostly restricted to winter and early spring. Precipitation of BSA by extract of oak leaves, apparently associated with hydrolyzable tannins, did not discourage oak consumption by goats. The digestibility of younger and older oak leaves was more influenced by time of incubation than level of phenolics in plant tissue. This research emphasizes the adaptability of goats to ecological zones where presence of toxins and digestion reducing compounds in plants adversely affects survival and fitness of non-adapted herbivores.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.