Assessing environmental consequences of using co-products in animal feed

Purpose

The livestock sector has a major impact on the environment. This environmental impact may be reduced by feeding agricultural co-products (e.g. beet tails) to livestock, as this transforms inedible products for humans into edible products, e.g. pork or beef. Nevertheless, co-products have different applications such as bioenergy production. Based on a framework we developed, we assessed environmental consequences of using co-products in diets of livestock, including the alternative application of that co-product.

Methods

We performed a consequential life cycle assessment, regarding greenhouse gas emissions (including emissions related to land use change) and land use, for two case studies. Case 1 includes increasing the use of wheat middlings in diets of dairy cattle at the expense of using it in diets of pigs. The decreased use of wheat middlings in diets of pigs was substituted with barley, the marginal product. Case 2 includes increasing the use of beet tails in diets of dairy cattle at the expense of using it to produce bioenergy. During the production of biogas, electricity, heat and digestate (that is used as organic fertilizer) were produced. The decrease of electricity and heat was substituted with fossil fuel, and digestate was substituted with artificial fertilizer.

Results and discussion

Using wheat middlings in diets of dairy cattle instead of using it in diets of pigs resulted in a reduction of 329 kg CO₂ eq per ton wheat middlings and a decrease of 169 m² land. Using beet tails in diets of dairy cattle instead of using it as a substrate for anaerobic digestion resulted in a decrease of 239 kg CO₂ eq per ton beet tails and a decrease of 154 m² land. Emissions regarding land use change contributed significantly in both cases but had a high uncertainty factor, ±170 ton CO₂ ha^?1. Excluding emissions from land use change resulted in a decrease of 9 kg CO₂ eq for case 1 ‘wheat middlings’ and an increase of 50 kg CO₂ eq for case 2 ‘beet tails’.

Conclusions

Assessing the use of co-products in the livestock sector is of importance because shifting its application can reduce the environmental impact of the livestock sector. A correct assessment of the environmental consequences of using co-products in animal feed should also include potential changes in impacts outside the livestock sector, such as the impact in the bioenergy sector.     

Role of antibiotic production by Erwinia herbicola Eh252 in biological control of Erwinia amylovora.

Erwinia herbicola Eh252 is a nonpathogenic epiphytic bacterium that reduces fire blight incidence when sprayed onto apple blossoms before inoculation with Erwinia amylovora, the causal agent of fire blight. Eh252 was found to produce on minimal medium an antibiotic that inhibited the growth of E. amylovora. This antibiotic was inactivated by histidine but not by Fe(II), was sensitive to proteolytic enzymes, and showed a narrow host range of activity. To determine the role of this antibiotic in the control of fire blight, two prototrophic Tn5-induced mutants, 10:12 and 17:12, that had lost their ability to inhibit E. amylovora on plates (Ant- mutants) were compared with the wild-type strain for their ability to suppress fire blight in immature pear fruits. The two mutants had single Tn5 insertions in the chromosome; although they grew in immature pear fruits at a rate similar to that of the wild-type strain, neither of these mutants suppressed fire blight as well as Eh252 did. The Tn5-containing fragment isolated from 10:12 was used to mutagenize Eh252 by marker exchange. Derivatives that acquired the Tn5-containing fragment by homologous recombination lost the ability to inhibit E. amylovora on minimal medium. Furthermore, the three Ant- derivatives tested were also affected in their ability to inhibit E. amylovora in immature pear fruits. The results obtained suggest that antibiotic production is a determinant of the biological control of E. amylovora by Eh252, but that another mechanism(s) is involved.     

Hydrolysis of intact and Cys-Phe-cleaved human atrial natriuretic peptide in vitro by human tissue kallikrein.

Atrial natriuretic peptide (ANP) is a 28-amino-acid hormone involved in the regulation of fluid balance. In circulation, the proteolytic inactivation of ANP has been demonstrated to involve both membrane metalloendopeptidase and an aprotonin-sensitive activity, probably corresponding to kallikrein [Vanneste, Y., Pauwels, S., Lambotte, L., Michel, A., Dimaline, R. & Deschodt-Lanckman, M. (1990) Biochem. J. 269, 801-806]. In the present study, we focused on the aprotinin-sensitive pathway of ANP metabolism. In order to identify the cleavage sites recognized by kallikrein within the sequence of the hormone, tissue kallikrein was purified to homogeneity from human urine and the degradation of human ANP by the enzyme preparation was studied. Our results demonstrate that both intact and Cys7-Phe8-cleaved ANP, the initial metabolite produced in circulation by the metallo-endopeptidase, are substrates in vitro for purified tissue kallikrein. However, the Cys-Phe-cleaved peptide was degraded approximately fourfold faster than the intact hormone by the purified enzyme. The first degradation step of ANP by tissue kallikrein involves two cleavages occurring at the bonds Arg3-Arg4 and Gly16-Ala17, generating an inactive, open-ring metabolite. Incubation of ANP for a longer period with the enzyme led to the generation of several additional degradation fragments. Ten peaks were separated by HPLC and characterized by amino acid analysis. The results allowed the identification of a total of eight peptide bonds susceptible to hydrolysis by tissue kallikrein in the sequence of ANP: Arg3-Arg4, Ser5-Ser6, Cys7-Phe8, Arg11-Met12, Gly16-Ala17, Gly20-Leu21, Ser25-Phe26 and Arg27-Tyr28. These results indicate that the aprotinin-sensitive activity involved in the metabolism of ANP in circulation could correspond to tissue kallikrein. However, clear identification of ANP as a novel physiological substrate of the enzyme will need further investigation.     

Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa

• Elevated atmospheric input of nitrogen (N) is currently affecting plant biodiversity and ecosystem functioning. The growth and survival of numerous plant species is known to respond strongly to N fertilisation. Yet, few studies have assessed the effects of N deposition on seed quality and reproductive performance, which is an important life‐history stage of plants.
• Here we address this knowledge gap by assessing the effects of atmospheric N deposition on seed quality of the ancient forest herb Anemone nemorosa using two complementary approaches.
• By taking advantage of the wide spatiotemporal variation in N deposition rates in pan‐European temperate and boreal forests over 2 years, we detected positive effects of N deposition on the N concentration (percentage N per unit seed mass, increased from 2.8% to 4.1%) and N content (total N mass per seed more than doubled) of A. nemorosa seeds. In a complementary experiment, we applied ammonium nitrate to aboveground plant tissues and the soil surface to determine whether dissolved N sources in precipitation could be incorporated into seeds. Although the addition of N to leaves and the soil surface had no effect, a concentrated N solution applied to petals during anthesis resulted in increased seed mass, seed N concentration and N content.
• Our results demonstrate that N deposition on the petals enhances bioaccumulation of N in the seeds of A. nemorosa. Enhanced atmospheric inputs of N can thus not only affect growth and population dynamics via root or canopy uptake, but can also influence seed quality and reproduction via intake through the inflorescences.

     

Respective roles of kallikrein and endopeptidase 24.11 in the metabolic pathway of atrial natriuretic peptide in the rat.

The metabolism of atrial natriuretic peptide (ANP) and Cys-105-Phe-106-cleaved ANP (ANP) was studied during constant infusion of 125I-labelled peptides in rats. Analysis of circulating radioactivity indicated rapid clearance of ANP and ANP', with mean half-lives of 0.42 and 1.04 min respectively. H.p.l.c. fractionation of plasma taken during the infusion of labelled ANP revealed the presence of three radioactive fragments, the major one co-eluting with 125I-ANP'. These fragments correspond to cleavage products previously found to be generated in vitro by the action of endopeptidase 24.11 (E-24.11). On evaluating the effects of peptidase inhibitors, a significant increase in the half-life of ANP was observed with phosphoramidon (t1/2 7.8 min) and aprotinin (t1/2 5.4 min). A maximal inhibition of ANP degradation was obtained when both inhibitors were given simultaneously (t1/2 15 min). In blood samples taken during infusion of 125I-ANP and phosphoramidon, the intact peptide accounted for more than 90% of total circulating radioactivity, and no cleavage product was present in detectable amounts. Phosphoramidon had no effect on the metabolism of infused ANP'. In contrast, when 125I-ANP' was infused together with aprotinin, the rate of degradation of the infused peptide was reduced by more than 80%. It is proposed that two different peptidase activities, E-24.11 and a kallikrein-like proteinase, are responsible for the cleavage of ANP in the circulation. The Cys-Phe-cleaved ANP would in turn be degraded by kallikrein and not by E-24.11.     

Antioxidant status of Fanconi anemia fibroblasts

Summary Several observations in the recent literature have indicated that Fanconi anemia (FA) cells may be primarily deficient in the detoxification of activated oxygen species. To evaluate the antioxidant status of FA fibroblasts, we measured Mn-containing superoxide dismutase (Mn-SOD), CuZn-containing superoxide dismutase (CuZn-SOD), catalase, and glutathione peroxidase activities, as well as cellular glutathione contents and total nonenzymatic antioxidant potential in Fa and control fibroblasts at multiple time point during a single passage. All parameters exhibited a characteristic pattern of changes during a period of 19 days following trypsinization. Unlike FA erythrocytes, which are known to be deficient in CuZn-SOD, FA fibroblasts exhibited normal CuZn-SOD activities. Also, the nonenzymatic antioxidant potential as well as glutathione levels were similar in FA and control fibroblasts. However, Mn-SOD, catalase, and glutathione peroxidase activities were consistently higher in FA fibroblasts. We hypothesize that the elevation of these enzyme activities might reflect a cellular prooxidant state in FA resulting from an increased formation of endogenous oxidizing molecular species that trigger enhanced synthesis of certain enzymatic antioxidant defenses.     

Mental training affects distribution of limited brain resources

The information processing capacity of the human mind is limited, as is evidenced by the so-called “attentional-blink” deficit: When two targets (T1 and T2) embedded in a rapid stream of events are presented in close temporal proximity, the second target is often not seen. This deficit is believed to result from competition between the two targets for limited attentional resources. Here we show, using performance in an attentional-blink task and scalp-recorded brain potentials, that meditation, or mental training, affects the distribution of limited brain resources. Three months of intensive mental training resulted in a smaller attentional blink and reduced brain-resource allocation to the first target, as reflected by a smaller T1-elicited P3b, a brain-potential index of resource allocation. Furthermore, those individuals that showed the largest decrease in brain-resource allocation to T1 generally showed the greatest reduction in attentional-blink size. These observations provide novel support for the view that the ability to accurately identify T2 depends upon the efficient deployment of resources to T1. The results also demonstrate that mental training can result in increased control over the distribution of limited brain resources. Our study supports the idea that plasticity in brain and mental function exists throughout life and illustrates the usefulness of systematic mental training in the study of the human mind.