Poultry science matters are discussed extensively every year during the International Poultry Scientific Forum (IPSF) in Atlanta, GA USA. The event is an excellent venue for sharing knowledge on both practical and in-depth science topics that are related to improving poultry production.
By Dr Simon M. Shane, Durham, NC, USA
The International Poultry Scientific Forum is held every year, prior to the International Poultry Exposition (IPE) in Atlanta, GA, USA. This year it attracted a multinational group of 1,200 attendees representing academia, industry and production. The program comprised 126 platform presentations and 135 scientific posters depicting advances in nutrition, physiology, product quality and safety and pathology.
International participation was the hallmark of the 2012 IPSF with presentations from the US, Canada, Brazil, Mexico, seven European nations, Thailand, India and Saudi Arabia. The scope of papers and the participation by researchers from universities and institutes confirms the close relationships which have been developed between professors and their students which transcend oceans.
The use of enzymes to enhance digestibility of a wide range of ingredients is now accepted as a routine industry practice. Improvement in feed conversion and hence reduction in cost is the major factor driving the adoption of enzyme supplementation. Environmental considerations, especially with respect to phosphorus, is significant in some areas where there is concern over eutrophication.
Scientists affiliated to Danisco Animal Nutrition and Massey University in New Zealand demonstrated the benefits of a combination of xylanase, amylase and a protease. Axtra XAP in diets incorporating maize, soybean meal and corn-derived dried distillers’ grains. Inclusion of the additive improved body weight of broilers at 42 days and feed conversion was enhanced especially in diets containing a wide range of ingredients.The same research team evaluated the effectiveness of carbohydrase and protease on ileal digestibility of energy, fat and protein in maize and wheat-based broiler diets.
Combination of xylanase and amylase were compared to an enzyme combination containing an additional protease marketed commercially as extra XAP. Starch digestibility was increased by both enzyme supplements compared to the control. The combination containing protease increased protein digestibility and both enzyme combinations enhanced digestion of fat.
The efficiency of an enzyme to degrade non-starch polysaccharide was investigated at the Nutreco Ingredient Research Centers in the Netherlands and Spain. It was demonstrated that supplementing diets with NSP enzymes could compensate for a reduction in the metabolisable energy content of the diet to optimise feed conversion and reduce costs.
Scientists affiliated with Novozymes in Denmark and colleagues at DSM Nutritional Products in the US reported on the efficiency of a commercial protease, Ronozyme ProAct in broilers. Their initial studies showed that the protease preparation could survive the acidic environment of the proventriculus and ventriculus which facilitated activity in the duodenum and ileum. It was clearly demonstrated that Ronozyme ProAct was compatible with phytase and xylanase enzymes, contributing to synergy in enhancing the digestibility of diets containing a full range of ingredients.
The occurrence of ascites in broilers with a high potential for growth, especially when reared at elevated altitudes, has been a problem for decades. Researchers at the Anthony University of Arkansas evaluated genetically susceptible, resistant and relaxed lines with respect to incidence of ascites. The focus of the studies was a correlation between the time of hatching and duration in the hatcher compartment before removal. Susceptible lines generally hatched earlier than resistant lines indicating the complexity of genetic and environmental interactions in the occurrence of ascites.
Studies conducted by the Anthony University group in conjunction with the University of Arkansas refuted the theory that hematocrit values were predictive for ascites. Studies conducted using simulated altitudes of 2,700 m and 3,700 m were conducted on broilers raised through six weeks of age. Lines which were resistant to ascites exhibited higher hematocrit levels than lines susceptible to ascites.
Since the broiler industry in Mexico endures a profound problem of ascites, there has been considerable research in this nation to reduce losses. The beneficial effect of growth modulation was demonstrated using feed restriction ranging from 92.5% to 97.5% of ad libitum intake. The study was undertaken at 2,700 m in Ecuador and restriction was imposed from 15 days of age onwards. The optimal level of restriction was determined to correspond to 95% of ad lib intake which allowed broilers to achieve 2.75 kg at 44 days with a feed conversion of 1.70. Total mortality was 3.2% of which 2% was attributed to ascites. The 95% reduction in feed intake yielded the lowest production cost based on broilers harvested.
It has been long known that furazolidone which induces cardiomyopathy will contribute to ascites. The condition was successfully reproduced by feeding 500 and 700 ppm furazolidone. Appropriate monitoring of serum enzymes including glutamic and oxaloacetic transaminases confirmed myodegeneration in live birds. This study is academic since furazolidone is no longer used in the broiler industries of industrialised nations.
Probiotics and prebiotics
There has been considerable interest in the use of prebiotics and probiotics or their combination as a replacement for antibiotic growth promoters. Studies conducted at the University of Manitoba investigated the effect of yeast derivatives, organic trace minerals and a combination of prebiotic and probiotic additives on the immune system. Stimulation of IgM levels was recorded at day 14 in chicks receiving a probiotic and prebiotic combination. It was presumed that this effect was due to modifying intestinal microflora.
The beneficial effect of combining a yeast-cell derived mannanoligosaccharide with a probiotic (Calsporin) was demonstrated in a replicate pen trial conducted by a contract research unit in the US. Broilers were fed a maize-soybean meal diet containing DDGS and meat meal. In both 42 and 47 day trials, body weight of broilers fed the combination showed higher weights than controls and corresponded to diets containing antibiotic growth promoters. A yeast cell wall derivative, Actigen produced by Alltech, was shown to be superior with respect to growth rate and feed conversion of broilers compared to non-medicated controls. There was no difference in live weight of broilers fed Actigen and birds receiving a combination of bacitracin and virginiamycin. The highest level of performance was obtained when Actigen was combined with antibiotics.
Studies conducted at the Scottish Agricultural Institute considered the effect of thermal stress during transport of broilers. Alternative ventilation systems installed on vehicles were evaluated to prevent heat stress and loss of moisture. By measuring flow rate of air, total metabolic heat production and the specific heat capacity of air it was determined that the effective ventilation rate for a fully loaded vehicle should be 0.6m3s-1 per tonne of live weight.
A prototype vehicle has been constructed to conform to this requirement and has demonstrated the capacity to reduce mortality and improve quality. Evaporative cooling of broilers is regarded as a necessity in areas with hot climates. Studies at the University of Arkansas evaluated overhead low pressure sprinklers in comparison to evaporative pad cooling systems. The use of sprinklers resulted in higher air temperature at lower relative humidity. There was no significant difference in the level of litter moisture after flocks were depleted. It was determined that the sprinkler system required less water than a conventional evaporative cooling installation.
Tunnel ventilation for broiler houses is now an accepted practice worldwide. Agricultural engineers at the University of Georgia have developed evaporative cooling systems and have defined the appropriate air velocity required for optimal bird comfort and growth. In a recent study, anemometers were arranged in a grid to characterise air flow patterns in houses. It was determined that average air speed in a broiler house could be determined by measuring velocity over the feed lines approximately 1.5 meters from the floor. During the past decade fan capacity has increased resulting in higher air speed which ranges from 180m/minute to 250m/minute. Due to higher velocity the area of cooling pads has been increased but this has resulted in “dead spots” near the front of the house. By reducing the opening of tunnel doors and curtains, greater uniformity of air distribution can be achieved.