畅想将来家禽饲料应该如何设计Mapping the future of poultry diet design

bonderic

A gathering of top feed specialists yields insight into the future direction of poultry diet design.


For anyone in Europe wanting to find future directions in poultry diet design, the place to look this year was the city of Strasbourg on the border between France and Germany. It hosted a gathering of top feed specialists from all parts of the continent and further afield to discuss the latest indications from research and practice.
The occasion was the 16th European Symposium on Poultry Nutrition. This international conference is held every two years under the auspices of the European Federation of the World's Poultry Science Association or WPSA, always in a different country. In 2007, the honor of arranging the program fell to the members of WPSA France.
They chose European and North American guest speakers with expertise on the processing of feeds as well as on dietary composition to meet estimated requirements. Among the subjects in the feed-processing area were the control of bacterial contamination of feedstuffs and the improvement in nutritive value obtainable from attending to particle size.
As this latter paper from Norway's Professor Birger Svihus confirmed, the hot topic of the moment has to be the influence of diet factors on so-called gut health. An example from broilers has been the demonstration that grinding feeds too finely, so that their particles are excessively small, is both wasteful on energy and counterproductive for the bird by interfering with the proper development of the gizzard.
It was put into perspective at the meeting when Feed International spoke to Jackie Linden, who is editor of our associated journal Poultry International. She emphasized that nutritional manipulation to optimize gut health had become a European quest across all monogastric feeding in the aftermath of the Europe-wide ban on including antibiotic growth promoter (AGP) supplements in feeds.
"The prohibition continues to shape ideas on nutrition, almost two years after it was introduced," she remarked. "By general consent again among the people attending the symposium in Strasbourg, we should not expect one single replacement or so-called magic bullet' to fill the gap left by the AGP removal. The way forward probably involves employing a series of different strategies according to particular conditions and objectives."
So while the poultry nutritionists of Europe still must take account of the fundamentals ranging from the growth rate and final value of broiler chickens to the egg output of laying hens, their focus now also extends to the maintenance of bird well-being by attending to the interaction between the feed and the bird's digestive tract. This orientation already has produced a wealth of new knowledge about the physical form of the gut and the microbiota that are its inhabitants.
Early establishment of microfloraJust how far the know-how has advanced in recent years was underlined by a Strasbourg presentation by Dr Richard Ducatelle of the University of Ghent in Belgium. The knowledge is considerable, he commented, although we are just now learning.. An example from his group's research has found that short-chain fatty acids inhibit mucosal invasion by Salmonella and increase the resistance of epithelial cells to invasion by Campylobacter. Butyrate seems to be particularly important. It follows that dietary changes which stimulate butyrate production in the lower digestive tract (or possibly feeding a coated formulation) could play a role in reducing food-borne illness. Early establishment of an adult microflora should be the aim, according to Dr Ducatelle.
Grinding feeds too finely, so that their particles are excessively small, is both wasteful on energy and counterproductive for the bird.Nutritional manipulation to optimize gut health had become a European quest across all monogastric feeding in the aftermath of the Europe-wide ban on including antibiotic growth promoter (AGP) supplements in feeds. "However," Poultry International's editor continued, "it would be wrong to think that the concentration on bird health begins and ends with the gut. We have heard a number of examples during the symposium in which diet was linked more widely to health status.
"Perhaps the most intriguing in this respect related to the feeding of broiler breeders. Feed companies sometimes forget these birds are a part of the poultry universe as if their numbers are too small to make a viable market, but on average there is one broiler breeder bird for every 100 broiler chickens in commercial production. Our own annual Executive Guide to World Poultry Trends tells us that over 48 billion broilers were produced worldwide last year, so you can see the breeding flock behind them must have consumed a considerable amount of feed.
"The aim of the latest nutritional research on breeders described at this meeting has been to try to transfer nutrient factors from hen to chick. It recognizes that the chick soon after hatching eats very little and therefore must rely on extracting sustenance from the yolk sac. With this in mind, transfer should probably work better for fat-soluble nutrients as they will need to enter the fatty yolk.
"The people doing the research say they hope both vitamins and minerals can be transferred from maternal nutrition as an aid to progeny performance. They target in particular the vitamins D and E together with selenium, zinc and manganese. In theory, these should be of benefit to the chick's immune system."
Feeding for behavior controlAt another level, the Strasbourg presentations raised the possibility of feeding for the control of behavior. Behavioral aspects impact directly on performance and profitability.
The clearest illustration of this came in a paper from the University of Wageningen in the Netherlands, where Marinus van Krimpen and colleagues have been investigating the Behavioral vice of feather-pecking that affects egg layers. There is general agreement that the vice is important economically because pecked birds tend to have inferior laying performance and also are unsuitable for normal processing when culled.
"The causes of feather-pecking still need to be fully explained, but it seems to be misplaced natural behavior," Jackie Linden commented. "Birds will quite normally investigate their surroundings by pecking at any object within range. They peck at the feathers of other members of the group if there is nothing else to occupy them. This is probably why fewer reports of feather pecking involve free-range birds than those in caged housing. Pullets and layers kept outside usually have other diversions.
"Experts also think there is a genetic effect. The egg markets of the world are divided clearly between white- and brown-shelled eggs. It is the brown-feathered layers that are more susceptible to serious incidents of feather-pecking.
"Of course if you work in a brown-egg market you are going to have brown layers, you do not have the choice of switching to the use of a white-feathered breed so that fewer birds will be pecked. But it is clear that feed composition can help to reduce the incidence of the vice. The Dutch team here have suggested that the principal aim in altering the layer diet should be to extend the feeding time. A hen will be less inclined to peck feathers if it is still eating.
"It becomes a question of bulk. They talked about using coarsely ground NSPs [non-starch polysaccharides] for this purpose, reporting moderate success from the manipulation. A good source of digestible fiber appears to assist by providing greater satiety or gut-fill. There may be a way to re-arrange formulation to accommodate a change of this type without sacrificing nutritional content. That will be one of the challenges to be resolved by further research."


Herbs are natural option for animal nutrition
How effective are herbs in replacing antibiotic growth promoters? That's a question that has garnered a great deal more attention as the industry continues to search for and evaluate natural alternatives for AGPs.
Professor Caspar Wenk, Federal Institute of Technology, Zurich, Switzerland, discussed the use of botanicals with participants of a symposium sponsored by DOSTOFARM GMBH held earlier this year.
Professor Wenk began by explaining what is meant by an herb. A herbaceous plant by definition is any plant which does not get a wooden stem. Along with herbs, interest in botanicals often leads to an examination of essential oils, which he pointed out differ from fat oils, such as sunflower oil, by the fact that they completely evaporate. They are sometime referred to as dry oils. Herbs and essential oils have gained attention in recent years as the animal nutrition industry has moved away from the use of antibiotic growth promoters.
He noted that herbs are feed additives, and not drugs which have only one defined substance and mode of action. Herbs are seen as natural' feed additives, have been generally proven effective, are non-toxic and well-accepted by the public. In addition, he said, there is about 3,000 years of experience in their use in China and worldwide.
But there are some drawbacks. Herbs can be variable in their composition, there is additional concern over mycotoxins, and there can be unanticipated interactions with other substances, for example.
Beneficial at times of stress
Like other feed additives, Professor Wenk noted the use of herbs is most beneficial and most effective at times of stress, including the presence of unfavorable environmental conditions, compromised health and/or low nutrient content of the diet. He also noted that unlike drugs, herbs as feed additives may have more than one mode of action. For example, certain herbs may increase feed consumption through taste while at the same impact fiber in the diet. Because herbs typically have more than one mode of action, their use often has many purposes, including improved feed intake and flavor, endocrine stimulation, anti-microbial activity, anti-viral activity, anthelmintic activity, coccidiostatic activity, immune stimulation, anti-inflammation, anti-oxidative activity and pigments
Professor Wenk gave examples of research into the use of specific herbs and the impact on animal health. For example, the addition of oregano has been shown to have antimicrobial properties against disease.
Nutritionists with the Ontario Ministry of Agriculture, Food and Rural Affairs, point out that herbal remedies as treatment for infectious diseases have a history dating thousands of years ago. Some herbs are thought to promote growth by preventing or limiting pathogenic bacteria in the digestive system, just like a conventional antimicrobial. Scientific and technological advancements eventually replaced those natural remedies with man-made products, as scientists learned more and more from the compounds found in herbs. Now, it seems, the tide has turned.
Improved feed efficiency
In Greece, researchers completed a series of experiments with the essential oils from oregano in the hopes of preventing and controlling post-weaning diarrhea in pigs. Results showed significant improvements in diarrhea score and live weight, with increases of 7-8 percent in daily gain and feed intake. A separate study, in pigs from weaning through to slaughter, found that pigs fed the oregano essential oils weighed 6-9 kg more than the untreated controls, showed a higher daily weight gain (6.5-10.5 percent) and improved feed efficiency (12-17 percent).
In 2005, researchers (Demir, E., Sarica, S., Özcan, M. A., Suicmez, M.) at the Department of Animal Science, Faculty of Agriculture, Gaziosmanpasa University, Tokat, Turkey, reported on a study involving the use of natural feed additives as alternative to an antibiotic growth promoter in broiler diets.
The researchers reported that differences in body weight gain, feed intake and feed efficiency of broilers fed diets supplemented with antibiotic growth promoter and five herbal natural feed additives were not significant from 0 to 42 d of age. In addition, some blood parameters and the concentration of E. coli in caecum were not significantly affected (P>0.05) by the dietary treatments.

bonderic

看来近年来，欧洲的动物营养学家对中草药提取物作为AGPs的替代物的研究也是大为感兴趣，从本次会议的内容来看，也是当今营养饲料学研究的一个热点。

monica

里面还有好多细节性的内容，比如关注禽的消化道，关注体内微生物区系等，仔细读读还是很有收获的，感谢楼主。