CABI Blogs: hand picked... and carefully sorted

Glycerol, a Byproduct of the Biodiesel Industry, in Livestock Feeds

The rapid growth of ethanol and biodiesel production in the United States and elsewhere has raised questions about possible uses for the byproducts of this industry. To date the use of ethanol byproducts, in particular distillers' dried grains with solubles, in animal feed has received much attention. The burgeoning biodiesel industry on the other hand, has resulted in glycerine, the principal byproduct, flooding the market. While glycerine is widely used in the soap, cosmetic and food industries, the biodiesel industry is producing more than the market can cope with. This has led to renewed efforts to find new uses for glycerine, e.g. as a boiler fuel source, as animal feed, for the production of propylene and ethylene glycol, and the possibility of glycerine replacing petrochemicals.

Although several studies have evaluated the use of glycerine in diets for poultry, pigs and ruminants [1-8], its high cost then meant it was not cost-effective to use as an animal feed. However, the current low cost of glycerine and its value as an energy source has prompted several research groups to evaluate the nutritive value of glycerine and its use in livestock diets.

Researchers at the University of Arkansas' Center of Excellence for Poultry Science examined the possibility of using glycerine as a dietary supplement in growing broiler chickens. In a short-term preliminary trial, Park Waldroup and his research team found that as much as 10% glycerine could be fed to to chickens up to 16 days of age without any detrimental effects on growth performance or meat quality. While 5% glycerine had no effect on body weight, feed intake, feed conversion or mortality, 10% glycerine affected feed flow rate (in the feeders used), reducing feed intake and consequently reduced body weight. Although the results suggest that glycerine can be used as an energy source in broiler diets, Waldroup cautioned that additional research was needed to evaluate the quality of the glycerine used and its effect on feed texture and pellet quality.

Researchers from Iowa State University and the US Department of Agriculture have been conducting studies on the feasibility of using glycerine in pig and poultry diets. In a metabolism study in which nursery and finishing pigs were fed 5, 10 and 20% glycerine, glycerine was readily used by pigs and found to have an energy value similar to corn. In a growth study, pigs fed on 5 and 10% glycerine from weaning to market weight showed the same growth performance as those fed on a conventional corn-soyameal diet. When 20% glycerine was used, flow rate problems were encountered leading the researchers to conclude that 10% inclusion was perhaps the upper limit. A metabolism trial conducted with hens fed on 0, 5, 10 or 15% glycerine showed no adverse effects on egg production, egg weight, or feed intake; the energy in the glycerine was also efficiently utilised. Although data from these trials on the effect of glycerine on meat quality have yet to be analysed, other studies suggest that the inclusion of glycerol can improve pig meat quality by reducing drip loss [5] and increase breast yield in broilers by improving protein deposition [9].

In a 6-month study that began this month at the University of Missouri-Columbia, Monty Kerley, professor of ruminant nutrition, is examining the effectiveness of glycerin (0, 5, 10 or 20%) as cattle feed using 60 calves from various breeds. In addition to monitoring feeding limits and growth patterns, glycerine metabolism in cattle will also be studied. Kerley sees the use of glycerine as cattle feed as a short-term option as he believes in time newer industrial applications for glycerine could price it out of the animal feed industry.

Thus glycerol appears to have promise as an energy source in animal diets. However, more studies are needed about the quality of glycerol from biodiesel production before its use can be recommended in animal feeds.

The CAB Abstracts database contains the abstracts of several papers on the use of glycerine in livestock diets.

References
[1] Kijora C, 1996. Utilization of glycerol as a byproduct of "Biodiesel" production in animal nutrition. Landbauforshung Volkenrode 169:151-157.
[2] Kijora C, Bergner H, Kupsch RD, Hagemann L, 1995. Glycerol as a feed component in fattening pigs. Archiv fur Tierernahrung 47:345-360.
[3] Kijora C, Kupscy RD, Bergner H, Wenk C, Prabucki AL, 1997. Comparative investigation on the utilization of glycerol, free fatty acids, free fatty acids in combination with glycerol and vegetable oil in fattening of pigs. Journal of Animal Physiology and Animal Nutrition 77:127-138.
[4] Kuhn M, 1996. Use of technical rapeseed-glycerol from Biodiesel production in the fattening of pigs. Landbauforshung Volkenrode 169:163-167.
[5] Mourot J, Aumaitre A, Mounier A, Peiniau P, Francois AC, 1994. Nutritional and physiological effects of dietary glycerol in the growing pig. Consequences on fatty tissues and post mortem muscular parameters. Livestock Production Science 38:237-244.
[6] Schröder A, Südekum K-H, 1999. Glycerol as a by-product of biodiesel production in diets for ruminants. 10th International Rapeseed Congress, Canberra, Australia. 6 pp. http://www.regional.org.au/au/gcirc/1/241.htm Accessed 31 May 2007.
[7] Simon A, Bergner H, Schwabe M, 1996. Glycerol as a feed component for broiler chickens. Archiv fur Tierernahrung 49:103-112.
[8] Simon A, Schwabe M, Bergner H, 1997. Glycerol supplementation to broiler rations with low crude protein content. Archives in Animal Nutrition 50:271-282.
[9] Cerrate S, Yan F, Wang Z, Coto C, Sacakli P, Waldroup PW, 2006. Evaluation of glycerine from biodiesel production as a feed ingredient for broilers. International Journal of Poultry Science 5:1001-1007.

Suggested further reading
Niles D, 2006. Combating the glycerine glut. Biodiesel 3:38-44. http://www.biodieselmagazine.com/article.jsp?article_id=1123 Accessed 31 May 2007.
Van Heugten E, 2007. Byproducts from energy production for swine. Swine News May 2007. North Carolina State Swine Extension, p. 2-4. http://mark.asci.ncsu.edu/Swine_News/2007/sn_v3004%20(May).htm Accessed 31 May 2007.
Waldroup PW, 2007. Biofuels and broilers - competitors or cooperators? Proceedings of the 5th Mid-Atlantic Nutrition Conference 2007, Zimmermann NG, ed, University of Maryland, Maryland, USA. http://www.ddgs.umn.edu/articles-poultry/2007-Waldroup-%20Biofuels%20and%20broilers%20(MANC).pdf  Accessed 31 May 2007.

Not all doom and gloom (but not far off)...

A news item from Botanic Gardens Conservation International (BCGI)  has reported on the Plant a Billion Trees campaign started in January.  The aim was to have 1 billion trees planted by the end of this year.  This target has not only already been met but more that 13 million trees over the 1 billion have been pledged, with the figure rising all the time. 

Rice fields on former mangrove forest, Sulawesi.  Mongabay.com

The idea came out of the UN Climate Change Conference in Nairobi, and is a worldwide tree planting campaign, but the Plant for the Planet: Billion Tree Campaign encourages the planting of trees in four key areas, namely:
(i) degraded natural forests and wilderness areas;
(ii) farms and rural landscapes;
(iii) sustainably managed plantations; and
(iv) urban environments.                     
United Nations Environment Programme (UNEP)

It is argued that planting trees in cooler climates may not help to combat global warming but the UNEP states that “the loss of natural forests around the world contributes more to global emissions each year than the transport sector.  Curbing deforestation is a highly cost-effective way to reduce emissions.”

I thought I would highlight this bit of cheer because in just the last few days plenty of bad news has been reported e.g., digging up the Malaysian forest to bury dead people; and the shrinking of New Zealand’s forests for the second year in a row, where “a third of forests being clear-felled - about 12,900ha - are not being replanted”.  This month it was also confirmed by researchers publishing in Science that “tropical deforestation produces 20 per cent of all carbon emissions caused by humans and destroys long-term carbon sinks”.  However we are doing our bit in the UK, threatening the stability of an ancient forest, and many of the species that live within it, by expanding an airport to enable 10 million more people a year to fly to wherever they need to go.

The volume of depressing news may be as much an indication of the way the global media reports what’s going on in the world, but a search in CAB Abstracts for deforestation, restricted to the last 6 months, gives 221 results – telling, whichever way you look at it.

Melamine contamination is spreading to meat and fish supplies

Melamine contamination of pet food in North America is more than two months old story now, but the end of crisis is still nowhere in sight. Thousands of dogs and cats that have eaten contaminated foods have suffered kidney problems or died, although there are somewhat conflicting reports as to the actual numbers of pets that were affected (see my previous blog). The US Food and Drug Administration (FDA) has identified melamine and melamine-related compounds in a consignment of wheat gluten and rice protein concentrate imported from China and used to make many brands of pet food as the main culprit.  Chinese suppliers are suspected of intentionally adding melamine to make it appear that their products were higher in protein content, which translates to a higher price. Melamine has no nutritional value but is about two-thirds nitrogen by weight, and nitrogen levels are often used as crude indicators of protein content in food commodities. It has been know for a long time that feed manufacturers may intentionally add melamine to animal feeds as a paper by Cattaneo & Ceriani (1988) demonstrated. The abstract of this paper can be seen in Animal Science database.

The FDA's findings triggered one of the largest pet food recalls in U.S. history. Since 16 March, 18 companies have recalled more than 5,600 pet food products. The recalls, however, do not seem to have come to an end. The latest addition to the recall list includes the dry dog food Nutra Nuggets, manufactured by Diamond Pet Foods of Meta, Missouri, which have tested positive for melamine and caused kidney problems in at least four dogs in California.

Climate change clock ticking for wild relatives

International Biodiversity Day is here, and CGIAR brings us news that climate change threatens the wild relatives of cultivated potatoes and peanuts. The CGIAR study warns that 61% of wild peanut and 12% of wild potato species could be made extinct over the next half century. This poses a problem for plant breeders and GM crop producers alike. Wild relatives are a vital source of genetic diversity for crop improvement and if that pool of resources is diminished, genes which confer resistance to pathogens for example, are lost.

Andy Jarvis of CGIAR explains "The vulnerability of a wild plant to climate change can depend on its ability to adapt by, for example, extending its range as warming in its native regions becomes too hot to handle. One reason wild peanut plants appear to be so vulnerable to climate change is they are largely found in flat lands and would have to migrate a long way to reach cooler climates, a predicament exacerbated by the fact that peanuts bury their seeds underground, a meter or less from the parent plant. That limits the speed at which seeds can move into more favorable climates. By contrast, plants in mountainous locations could theoretically survive by extending their range slightly up a slope, even by only a few meters, to find cooler weather."

International Day for Biological Diversity

Today, May 22nd 2007, is “International Day for Biological Diversity”.

As designated by the Secretariat of the Convention on Biological Diversity, the theme of the day, this year, is to raise awareness of the link between Biodiversity and Climate Change. If you visit here, the Secretariat has provided resources (posters and videos) in six different languages, covering most of the global population, to help draw attention to this year’s theme.

According to a statement on the Secretariat website “climate change is already forcing biodiversity to adapt either through shifting habitat, changing life cycles, or the development of new physical traits. The recently extinct Golden Toad (Bufo periglenes) and Gastric Brooding Frog (Rheobatrachus silus) have already been labelled as the first victims of climate change.”

Given the importance of the climate change biodiversity link, the Secretariat concludes with four key aims that we should undertake on a global scale:

1. Conserve biodiversity that is especially sensitive to climate change.

2. Preserve habitats so as to facilitate the long-term adaptation of biodiversity.

3. Improve our understanding of climate change biodiversity linkages.

4. Fully integrate biodiversity considerations into mitigation and adaptation plans.   

Hunting both animals and plants

Many people are aware of the negative effects of hunting on the species that are being hunted, especially on large-bodied, slow-reproducing forest vertebrates, but have you ever considered the knock-on effects on the plant community in those same ecosystems? The latest issue of Biotropica (vol. 39, no. 3) features a special section on the ‘Pervasive consequences of hunting for tropical forests’, which looks at the consequences of hunting on seed dispersal and plant species composition.

Hunting levels have been increasing, especially over the last 50 years when the importance of hunting for subsistence has been increasingly outweighed by hunting for the market. Drs Carlos Peres and Erwin Palacios report that "The total extent of partially defaunated, but otherwise "pristine" tropical forests, is often severely underestimated. For example, subsistence hunters have access to most areas of lowland Amazonia, affecting even the core of many relatively remote nature and indigenous reserves". Several factors are contributing to the overexploitation of forest game. Dr Joseph Wright and his colleagues write "The weak economies of many tropical countries fail to provide sufficient jobs for their growing populations, while land-use change, improved infrastructure, and new technology facilitate commercial hunting." Land-use change, often resulting in fragmentation, brings hunters and their markets closer to previously remote forests, while improved infrastructure, for example building of roads for timber and mineral extraction, provides access to forest interiors and to distant urban markets. All of this leads to an increase in the return for time spent hunting.

Virus Threatens Scotland's Red Squirrels

The first case of a red squirrel in Scotland dying as a result of the squirrelpox virus has sadly been reported by Scottish Natural Heritage. The red squirrel (Sciurus vulgaris) is one of the most threatened species of mammal in the UK, and Scotland supports 75% of the UK's remaining red squirrel population.

Squirrelpox virus was first detected in Scotland in invasive populations of non-native grey squirrel (Sciurus carolinensis) in May 2005. The competing grey squirrels carry the virus, showing no signs of disease, but when transmitted to the native red squirrel the virus is invariably fatal. Targeted grey squirrel control has helped prevent the progression of the disease to Scottish red squirrels until now.

Squirrelpox virus is known to be one of the significant factors in the catastrophic decline of red squirrels in the UK. The virus has caused the deaths of hundreds of red squirrels in England and, in February, a red squirrel died for the first time in Wales from the virus. Whilst searching CAB Abstracts for information, it was worrying to read that the rate of red squirrel replacement by grey squirrels is some twenty times faster in those areas where grey squirrels carry the virus^1,2.

In February 2006, a conference on Red squirrel conservation in Scotland resulted in the preparation of The Scottish Red Squirrel Action Plan 2006-2011 which makes a number of recommendations for the long-term conservation of the species, including development of a vaccine against squirrelpox virus. Let's hope the plan works.

To search CAB Abstracts comprehensively for squirrelpox virus, note the following variations of the virus name: squirrel parapoxvirus, squirrel poxvirus
(The virus was originally classified as a parapoxvirus but recent phylogenetic analyses suggests that this is incorrect^3,4).

1. Squirrel poxvirus: landscape scale strategies for managing disease. Gurnell, J., Rushton, S. P., Lurz, P.W.W., Sainsbury, A.W., Nettleton, P., Shirley, M.D.F., Bruemmer, C., Geddes, N. Biological Conservation, 2006, Vol. 131, No. 2, pp. 287-295.2.
2. Disease threats posed by alien species; the role of a poxvirus in the decline of the native red squirrel in Britain. Rushton, S.P., Lurz, P.W., Gurnell, J., Nettleton, P., Bruemmer, C., Shirley, M. D., Sainsbury, A. W. Epidemiology and Infection, 2006, Vol. 134, No.3, pp. 521-533.
3. A novel poxvirus lethal to red squirrels (Sciurus vulgaris). Thomas, K., Tompkins, D.M., Sainsbury, A.W., Wood, A.R., Dalziel, R., Nettleton, P.F., McInnes, C.J. Journal of General Virology, 2003, Vol. 84, No. 12, pp. 3337-3341.
4. Genomic characterization of a novel poxvirus contributing to the decline of the red squirrel (Sciurus vulgaris) in the UK. McInnes, C. J. , Wood, A. R. , Thomas, K. , Sainsbury, A. W. , Gurnell, J. , Dein, F. J. , Nettleton, P. F. Journal of General Virology, 2006, Vol. 87, No. 8, pp. 2115-2125.

The art of...boiling broccoli

Anyone out there still boiling your broccoli - stop now! Research from the University of Warwick says that this treatment seriously reduces the cancer fighting glucosinolate content- up to 77% if you do it for half an hour. They also suggest that freezing is not the best way to store these vegetables as it also reduces glucosinolate levels.

My reaction to this bit of news was - yes interesting about glucosinolate content after cooking and also interesting that storage in the freezer appears not to be good for glucosinolate content either especially as some vitamins are preserved by freezing, but - half an hour? Who does that these days? The broccoli would be falling apart! A straw poll round the office shows 10 minutes would be more usual. According to the research however, this still inflicts substantial losses of glucosinolates- up to 50%.

What cooking method is best to maximise one’s glucosinolate intake then? Well the researchers say steaming and frying for a few minutes are OK and this in agreement with some previous research (see search below). However a paper by Conway et al.¹ suggests brassicas like broccoli and cabbage are actually better eaten raw because myrosinase, the enzyme needed to convert the glucosinolates into cancer fighting isothiocyanates is then more active - heating inactivates it.

Why did people get into the habit of boiling their green vegetables for so long anyway? Apart from perhaps being uninterested in their food or too busy, that is. This paper by Niti Sharma et al.² is giving the clue - bitter taste. Glucosinolates taste bitter and boiling reduces the bitterness. You can’t win. Plant breeders and food scientists are getting headaches over the problem of reducing bitter taste but keeping the phytochemicals. For a review on consumers and the bitter taste in vegetables see Drewnowski et al.³

If you do still want to boil your greens to death, perhaps you should drink the cooking water too or use it to make something else, then you’ll get the leached glucosinolates back. My grandmother was right to press that ‘cabbage water’ on me. maybe she got her advice from this BMJ paper from 1941.⁴

¹ Disposition of glucosinolates and sulforaphane in humans after ingestion of steamed and fresh broccoli
Conaway, C. C. , Getahun, S. M. , Liebes, L. L. , Pusateri, D. J. , Topham, D. K. W. , Botero-Omary, M. , Chung, F. L. / Nutrition and Cancer, 2000, Vol. 38, No. 2, pp. 168-178, 38 ref.

²Effect of maturity and boiling on glucosinolate content of cruciferous vegetables
Niti Sharma , Swati Bansal / Indian Journal of Nutrition and Dietetics, 2004, Vol. 41, No. 10, pp. 421-425, 17 ref.

³Bitter taste, phytonutrients, and the consumer: a review
Drewnowski, A. , Gomez-Carneros, C. / American Journal of Clinical Nutrition, 2000, Vol. 72, No. 6, pp. 1424-1435, 137 ref.

⁴ The Preparation and Cooking of Green Vegetables.' BRITISH MED. J, 1941 pp. 26-7.

Search CAB Direct (subscribers only) Glucosinolates and cooking

Taking the sting out of nettles

A colleague has just told me that it's 'Be Nice to Nettles Week' - I know it may seem strange to celebrate the merits of such a commonplace plant but the humble nettle has many uses. I have sampled nettle soup and Cornish Yarg wrapped in nettles reputedly to encourage the cheese to ripen (although this also makes the cheese look very attractive). The leaves have a vast number of medicinal uses (once you've got beyond the sting!) whilst fibres from mature stems can be woven into cloth. Nettles are also a good source of natural dyes - green from the shoots and leaves and yellow from the roots.

A quick delve into CAB Abstracts revealed a huge 1080 records on Urtica dioica (an easy Latin name to remember as it really does 'urt when you get stung!) with papers ranging from the use of nettles in medicinal teas and in pig feeds through to increasing biodiversity in your garden.

'Be Nice to Nettles Week' runs from 16-27 May and includes a series of events which start tomorrow.

Disturbing Soil Has Disturbing Effects on Forest Carbon

Forests are seen as a major plank in trying to reduce carbon emissions to mitigate climate change. According to the rules of the Kyoto Protocol and of the United Nations Framework Convention on Climate Change, forestry can generate a sink for greenhouse gases that can contribute to meeting the national commitments to emissions reductions. However, as Robert Jandl of the Austrian Federal Office and Research Center for Forests and his colleagues point out, such as wetlands and peatlands may even be a source of greenhouse gases when they are afforested. How forests are managed also has important effects on how much carbon is absorbed.

Writing in CAB Reviews, Jandl and colleagues described how as part of the IUFRO Task Force on Carbon Sequestration they analysed the effects of harvesting, rotation length, thinning, fertilizer application and tree-species selection on carbon sequestration. All of these have an impact on the forest productivity and consequently on carbon sequestration in the ecosystem. In terms of carbon sequestration and its accounting in national greenhouse-gas budgets, ecosystem stability is highly rated. “Forests that are robust against disturbances up to a certain degree of severity are better suited for political commitments than stands of maximum productivity with a high risk of damages,” say Jandl and his colleagues. “Optimized forest management with regard to soil C sequestration should aim to secure a high productivity of the forest on the input side, and avoid soil disturbances as much as possible on the output side.”

The paper "Carbon sequestration and forest management" by Robert Jandl, Lars Vesterdal, Mats Olsson, Oliver Bens, Franz Badeck and Joachim Rock appears in CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources, 2007, 2, No. 017.

Read the full review