Food intake adjustments of chicks: Short term reactions of genetic stocks to deficiencies in lysine,methionine or tryptophan

1. Growth, food intake, and food preference were measured in two experimental lines (White Rocks and White Leghorns) of chickens fed diets varying in content of lysine, methionine, or tryptophan. Diet A was balanced in all amino acids, while the remaining 6 diets were moderately ( ～ 30%) or slightly ( ～ 15%) deficient in either lysine, methionine, or tryptophan relative to NRC recommendations for broiler diets.

2. Body weight and food utilisation efficiency of White Leghorns at 10 d of age were not affected by diet, whereas the lower concentrations of lysine and methionine depressed these traits in White Rocks.

3. Tryptophan deficiency reduced food intake of White Leghorns, but not White Rocks.

4. With choice feeding of balanced and deficient diets from day 10 to 16, preferences between the diets were minimal for White Leghorns, whereas for White Rocks there was an almost immediate preference for the balanced diet, followed by lack of preference or preference for the deficient diet.

5. Apparently for some genetic stocks there is rapid adjustment to deficiencies in these amino acids with overconsumption, followed by compensation for preference of the balanced diet. The response, however, will vary depending on the deficient amino acid.     

Phytoavailability of lead altered by two Pelargonium cultivars grown on contrasting lead-spiked soils

Purpose

This study assesses the potential of two contrasted fragrant Pelargonium cultivars to induce pH and dissolved organic carbon (DOC) changes in the soil solution, Pb speciation, and their subsequent effects on rhizosphere phytoavailable Pb.

Materials and methods

Rooted plantlets were grown in special devices, floating on aerated nutrient solution in PVC tanks. This setup allows roots to be physically separated, through a mesh, from a 3-mm soil matrix layer that can be considered as rhizosphere soil. Two contrasted soils, each spiked with Pb-rich particles, emitted from a battery recycling industry, were used at total burdens of 500 and 1500 mg Pb kg^?1 in addition to a control unspiked soil. Soil solution pH, phytoavailable Pb, DOC, Pb adsorption, precipitation on roots, and Pb phases in soil and plant were investigated.

Results and discussion

Attar of Roses (Attar) cultivar acidified its rhizosphere by 0.4 pH units in both spiked soils. Concolor Lace (Concolor) was unable to change soil solution pH on soil-1 and increased it by 0.7 units on soil 2. Concentrations of Pb in soil solution from Attar plants were always higher than those of Concolor ones. DOC contents of both unspiked soil-1 and soil-2 without plants were not significantly different. In the case of spiked samples, DOC contents in the rhizosphere soil were increased by three and two times for Attar and Concolor, respectively, compared to the unspiked soil without plant. Both cultivars were able to increase DOC contents, independent of soil type and level of contamination. Accumulation of Pb in shoots and roots was higher in Attar as compared to Concolor due to enhanced available Pb as a result of pH and DOC modifications of the rhizosphere soil. Significant amounts of Pb were adsorbed on roots of both cultivars. X-ray elemental analysis of precipitates on roots revealed the association of Pb with P in cylinder-like structures. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that Pb was present, to a major extent in the inorganic form, mainly as PbSO₄ in the soil, whereas it was complexed with organic species within plant tissues. The conversion of Pb into organic species could decrease toxicity, may enhance plant tolerance, and could increase translocation.

Conclusions

Plant-induced changes were responsible for the modification of lead phases within the soil. Immobile forms present in the source leaded particles as well as in the soils were converted into soluble species, ultimately improving the phytoavailable or soil solubilized Pb.

     

How Uncontrolled Urban Expansion Increases the Contamination of the Titicaca Lake Basin (El Alto,La Paz,Bolivia)

Cities in developing countries encounter rapid waves of social transformation and economic development where the environment is mostly a neglected aspect. The Katari watershed encompasses mining areas, El Alto city (one of the fastest growing urban areas in South America and the biggest in the Altiplano) as well as agricultural areas. Its outlet is Cohana Bay, one of the most polluted areas of Lake Titicaca. Here we propose an integrative approach (hydrological, physicochemical, chemical and bacterial data) to understand the pollution problem of this developing area, in which a variety of anthropogenic activities takes place. Both mining and urban areas appear to be sources of metal pollution. Nutrient and bacterial contaminations are mainly related to urban and industrial discharges. These situations have impacts in the basin from the mining area down to Cohana Bay of Lake Titicaca. Pollutant concentration patterns are highly influenced by seasonal hydrology variations. The poor quality of surface waters in the basin represents a risk for human and animal populations, as well as for the quality of aquifers located underneath El Alto city.     

Food intake adjustments of chicks: Short term reactions to deficiencies in lysine,methionine and tryptophan

1. Two experiments were conducted to compare food intake responses of broiler chicks fed diets varying in lysine, methionine, and tryptophan. Diet D was formulated to create simultaneous deficiencies of lysine, methionine, and tryptophan. Diet A matched National Research Council (1984) recommendations for broilers, and diets B and C were, respectively, 2:1 and 1:2 mixes of diets A and D.

2. Short‐term food intake can provide information on the sequences of adaptation of chicks to a diet deficient in essential amino acids.

3. Chicks consumed 26% less of diet D than A during the first 24 h posthatch. When chicks fed diet A or D to 7 d of age were then fed one of 4 diets singly, within 24 h intake was lowest for chicks fed diet D. Within 48 h, food intake of diet C was more than that of diet D and less than that of diet A, while for diet B intake was more than of diet D but not different from diet A.

4. In the second experiment, chicks were fed diet A to 8 d and then diets A or D alone or given a choice of diets A and D from 8 to 20 d of age. Within 4 to 8 h, food intake of chicks fed diet D alone decreased markedly followed by partial recovery within 24 h. In a choice setting, consistent preference of Diet A over Diet D was observed within 7 h followed by stabilisation at about 65% diet A to 35% diet D.

5. Chicks fed diet D alone from 8 to 20 d of age, then placed in the same choice situation preferred diet A to D with a delay of less than one h and stabilisation at about 85%. Chicks provided a choice of diets A and D from 8 to 20 d, and then diet D alone reduced their food intake more quickly than those not given a choice initially.

6. Broiler chicks appear to react to amino acid deficiencies within a short period (hours) by adjusting their feed intake and/or selection. The response is influenced by age and prior experience.