By combining an appropriate barley cultivar, tailored NSP-degrading enzymes and intermittent feeding, Muhammad Ahmad’s PhD research demonstrates how Norwegian barley can be utilized to a much greater extent in broiler nutrition.
In his doctoral research, Muhammad Ahmad investigated how barley cultivar, enzyme supplementation and feeding regimen affected growth performance, nutrient digestion and gut health in broiler chickens. The findings showed that a combination of low-viscosity barley, NSPase supplementation, and intermittent feeding produced the most favorable outcomes for both feed utilization and bird health.
Barley is Norway’s most widely cultivated cereal crop and is an important ingredient in feed for both cattle and pigs. In broiler production, however, its use has been limited. The main reason is that barley contains soluble dietary fibers, known as non-starch polysaccharides (NSP), which can increase intestinal digesta viscosity and thereby impair nutrient utilization and gut health. These non-starch polysaccharides can be partially broken down by fiber-degrading enzymes known as NSPases.
However, studies have reported inconsistent effects when NSPases are added to barley-based diets. Ahmad suggested that these differences may be related to variations between barley cultivars and to the way broiler chickens are fed. Under continuous feeding, chickens do not make much use of their crop, which may mean that the enzymes begin breaking down the non-starch polysaccharides later in the digestive system.
These challenges formed the basis of Ahmad’s investigations.
Significant variation among barley cultivars
In the first part of the study, Ahmad evaluated seven modern spring barley cultivars from 12 different environments. The analyses revealed substantial differences among cultivars with respect to protein content, starch content and viscosity-related characteristics.
Two cultivars were of particular interest. When the two cultivars were subjected to digestion in the laboratory, one exhibited very low viscosity, whereas the other resulted in very high viscosity. These cultivars were subsequently selected for broiler feeding trials.
Broilers adapt to intermittent feeding
A central question in the PhD project was whether feeding strategy could influence digestive processes. In the experiments, some birds were given continuous access to feed, while others were exposed to an intermittent feeding regimen with defined feeding periods separated by fasting intervals.
The results showed that broilers rapidly adapted to intermittent feeding. They consumed feed more intensively during feeding periods and exhibited substantially greater crop fill (the amount of feed held in the crop) than birds with continuous access to feed.
The increased crop fill prolonged feed retention time in the upper gastrointestinal tract. Ahmad also observed that the supplemented NSPase enzymes started to work already in the crop.
A combination of strategies yields the best results
In the third and most comprehensive study of the dissertation, the effects of barley cultivar, NSPase supplementation and feeding regimen were evaluated simultaneously. Barley made up more than half of the feed.
Birds fed the high-viscosity barley cultivar showed increased water intake, wetter excreta, greater litter caking and poorer feed utilization. Ahmad also observed a higher abundance of a bacterial species associated with necrotic enteritis, an intestinal disease that affects poultry.
Enzyme supplementation reduced digesta viscosity, enhanced growth performance and lowered the prevalence of undesirable bacteria. Although the addition of NSPase enzymes markedly improved these outcomes for both barley types, the results with high-viscosity barley were still not as good as those with low-viscosity barley.
The best results were achieved through the combination of all three strategies. Low-viscosity barley, NSPase supplementation and intermittent feeding acted additively, improving protein digestibility, feed conversion and gut health.
Potential to reduce reliance on imported feed ingredients
The dissertation demonstrates that the challenges associated with the use of barley in poultry production are not necessarily inherent to the raw material itself, but rather to the way it is utilized. Increased incorporation of Norwegian barley in broiler diets could reduce dependence on imported feed ingredients and contribute to a more self-sufficient food production system.
Dissertation defense
Muhammad Ahmad will defend his PhD thesis on 6 October, entitled: “Optimising barley for broilers through variety selection, NSPase supplementation and intermittent feeding”.
Professor Birger Svihus (NMBU) served as principal supervisor. Co-supervisors were Dr. Adam Smith (Novonesis AS, Hungerford, United Kingdom) and Dr. Siri Kulberg Sjurseth (Nortura SA, Oslo, Norway).