Levels Of Various Nutrients Research Articles

Multiple-Generation Bioassay for Investigating Western Spruce Budworm (Lepidoptera: Tortricidae) Nutritional Ecology

A three-generation bioassay was developed to determine the response curves of the western spruce budworm, Choristoneura occidentalis Freeman, to compounds that occur in the foliage of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, one of its principal hosts. Insects from a nondiapausing laboratory colony of C. occidentalis were reared on artificial diets containing defined levels of various nutrients and allelochemicals. An experimental base diet (nutritionally similar to Douglas-fir foliage in concentrations of nitrogen, sugars, and minerals) was modified to test responses. Insects spent their entire larval period, for three consecutive generations, feeding on the treatment diets. Responses measured include survival rates for all life stages, pupal masses, and larval development times and growth rates. Data on survival and fecundity (predicted from female pupal masses) were used to estimate population growth over three generations for the levels of the compound(s) tested. The tremendous variation in the survival and reproduction of C. occidentalis among 29 replications of the bioassay on the experimental base diet emphasizes the importance of replicating whole experiments for this type of bioassay. The great variability that occurred in these feeding studies underscores the critical importance of using large sample sizes and proper controls on each experiment to ensure that conclusions made from feeding bioassays are reliable. Average performance on the base diet was: 68% of the first instars survived to the late larval stage, 57% of the initial cohort survived to the pupal stage, 40% of the cohort survived to the moth stage, 45% of the egg masses produced had viable eggs, mean fresh pupal mass was 97 mg for females and 66 mg for males, mean larval development time was 44 d for females and 40 d for males, and larval growth rate was 2.3 mg/d for females and 1.7 mg/d for males.

Multiple-criteria decision-making techniques and their role in livestock ration formulation

The livestock ration formulation problem is postulated within the framework of multiple-criteria decision-making techniques. This exercise is motivated by the fact that the ordinary least-cost approach can, and does, generate solutions that either cannot be implemented or supply nutritionally undesirable levels of various nutrients. This originates from using cost as the criterion for selecting the ingredients of the diet. But in fact, diet formulation problems involve several criteria and should, therefore, be solved using techniques designed for modelling such problems. This paper is an attempt at introducing these techniques to agricultural systems modellers and then demonstrating their use in livestock ration formulation. The multiple-criteria decision-making techniques covered include goal programming and its variants such as weighted and lexicographic approaches and multiple-objective programming.

Effect of nutrients on the toxicity of pesticides carbofuran and hexachlorocyclohexane to blue‐green alga Nostoc muscorum

AbstractThe effects of various levels of nutrients like potassium phosphate (dibasic), calcium nitrate, and calcium chloride individually and in combinations were studied on the toxicity of the commonly used pesticides carbofuran and hexachlorocyclohexane (HCH) in growth medium to the N2‐fixing blue‐green alga Nostoc muscorum. It was observed that all these chemicals had some effects on toxicity. The toxicity of both carbofuran and HCH was reduced to some extent in the presence of higher concentrations of the nutrients when compared to normal levels of the chemicals in the medium. The higher doses of nutrients in combinations antagonized the effect of individual treatment and enhanced the toxicity of pesticides.

INFLUENCE OF FORM OF NITROGEN AND pH ON GROWTH AND NUTRIENT LEVELS IN THE LEAVES AND ROOTS OF THE LOWBUSH BLUEBERRY

In a water culture study with lowbush blueberry (Vaccinium angustifolium Ait.), growth was significantly better at pH 4.5 than at pH 6.0 (22.9 g new growth per plant compared with 9.6 g) and with NH4-N than with NO3-N (21.9 g compared with 10.7 g). The absence of a significant pH × form of N interaction suggested that the effects of pH and form of N were independent. Form of N and pH also affected the levels of various nutrients in the leaves and roots.

Zinc and Potassium Effects on Bone Formation, Feathering and Growth of Poults

ABSTRACT IN STUDIES with poults, utilizing a washed Drackett protein-sucrose basal diet calculated to be adequate in known nutrients, a mixture of unidentified growth factor supplements was found to markedly improve growth and to be protective against a non-rachitic hock disorder of undetermined etiology (Supplee et al., 1956; Supplee, 1957). The ash of this mixture as well as the ash of corn distillers’ dried solubles was found to promote approximately one-half as great a growth response as the supplement mixture but failed to improve the hock condition. Tests of higher levels of various nutrients, including minerals, had not improved either growth or hock condition. O’Dell and Savage (1957) obtained an increase in growth with chicks upon adding 0.5% KCl and 0.01% ZnCO3 to a Drackett protein-cerelose diet containing 0.116% added potassium and 6.6 ppm. added zinc. The effects of KCl and ZnCO3 added singly were less clear. As the potassium content . . .