This research was conducted to determine the potential of hulless winter barley (Hordeum vulgare L.) as an improved feed crop in the mid-Atlantic region. Winter barley is an excellent crop in rotation with soybean (Glycine max L.); however, production of winter barley during the past few years has decreased mainly due to low market prices, even though the mid-Atlantic region is a feed grain deficient area. Therefore, value added traits need to be developed in order for barley production to continue in the region. In the first part of this study, the objectives were to: (i) evaluate the agronomic performance and potential of six experimental hulless winter barley lines compared with two commercial hulled cultivars; (ii) determine and compare fiber, b-glucan, protein, and fat concentrations, and true metabolizable energy, corrected for nitrogen (TMEn) among these genotypes; and (iii) evaluate the genetic potential of winter hulless barley accessions from the world collection for use as parents in hulless breeding programs. Six hulless lines all derived from the cross VA75-42-45/SC793556//CI2457 were acquired from Clemson University in South Carolina. The six lines were evaluated for yield, test weight, heading date, plant height, and lodging. These hulless lines along with two hulled cultivars were planted in replicated yield plots in four states with a total of eight locations, and were managed according to standard recommended practices. Grain from each of the hulless lines and hulled checks, along with that of Trical 498 triticale (X Triticosecale) and Jackson wheat (Triticum aestivum L.) were analyzed for fiber, b-glucan, fat, protein, and ash concentration, and TMEn value. Eight hundred and seven winter or facultative habit hulless barley lines were obtained from the USDA-ARS National Small Grains Collection in Aberdeen, ID. These lines were screened for reaction type to races 8 and 30 of barley leaf rust (Puccinia hordei) and to a composite population of powdery mildew (Blumeria graminis f. sp. hordei). These accessions also were planted in observation rows to evaluate heading date, plant height, lodging, and seed threshability. The hulless lines yielded 23% less, but had 13% higher test weights than the hulled check cultivars. There was no difference between hulled and hulless barley in heading date and plant height. Hulless lines had a higher protein and lower fiber concentration than hulled barley. They also had higher b-glucan and fat concentrations than triticale or wheat. TMEn was similar between hulled and hulless barley, triticale, and wheat. Approximately 100 hulless barley lines from the world collection were selected for potential use as parents among 800 accessions tested, based on evaluations of lodging, plant height, threshability, and seed color. In the second part of the study the objectives were to determine the effects of (i) hulled and hulless barley, and (ii) b-glucanase on the performance of broilers fed different diets from 21 to 42 days of age. Diets comprised of 30% hulless or hulled barley, and a standard corn (Zea mays)/soybean meal diet with and without b-glucanase enzyme were evaluated to determine the effects of barley on gut viscosity, carcass weight, gain, percent shell, and feed efficiency in 21 to 42 day old broilers. In the first year, diets comprised of hulless lines SC890573 and SC860972, and the hulled cultivar Callao were compared to a standard check diet. In the second year SC860972 was replaced with SC880248 due to the inability to secure a sufficient amount of seed. Each year one hulled and two hulless barley diets were compared to a standard diet. Each diet was fed with and without enzyme, for a total of eight diets. Broilers 21 days of age were fed the diets until day 42 when they were processed. There was a significant decrease (P<0.05) in gut viscosity of birds fed diets with enzyme compared to birds fed diets without enzyme; however, gut viscosity did not affect weight gain or percent shell. Barley substituted at the 30% level did not have a significant effect on broiler performance, nor did the addition of enzyme. Absence of enzyme effect was attributed to bird age, since older birds are able to hydrolyze b-glucan more effectively than juveniles. The potential of hulless barley as an improved feed source for the poultry and swine industry is great for the mid-Atlantic region. Increases in grain yield are currently being realized through focused breeding efforts, and hulless lines exhibit positive nutritional components that combine favorable attributes of both wheat and hulled barley. Barley substituted at the 30% level in the diets of broilers did not cause any detrimental effects. Addition of hulless barley may potentially lead to a reduction in cost per pound of gain of broilers, and provide an alternative crop for mid-Atlantic region grain producers and feeders. / Ph. D.

The overall objective of this study was to evaluate the effects of feeding hulless barley and supplementing a xylanase enzyme on production performance and nutrient utilization of lactating dairy cows. In study 1, we evaluated production performance, milk fatty acid composition, and nutrient digestibility in high-producing dairy cows consuming diets containing corn and hulless barley in different proportions as the grain source. We hypothesized that a plausible reduction in production performance would be explained by an altered rumen function, which would be reflected in a reduction of the proportion of de novo fatty acids in milk fat. The inclusion of hulless barley grain as the energy source in diets for lactating dairy cows resulted in similar production performance and nutrient utilization as corn grain. We concluded that hulless barley is as good as corn grain as an energy source and increasing NDF concentration in hulless barley-based diet is not necessary. In study 2, we evaluated production performance, nutrient digestibility, and milk fatty acid composition of high-producing dairy cows consuming diets containing hulled or hulless barley as the grain source. We hypothesized that rumen function is altered when cows are fed low-forage diets containing barley grains, and this altered rumen function would be reflected in lower production performance and a reduction of fatty acids synthesis in the mammary gland. Contrary to our expectations, feeding hulled barley or hulless barely based diets with different forage to concentrate ratios to lactating dairy cows resulted in similar production performance and nutrient utilization. We concluded that both hulled or hulless barley grains are good energy sources for sustaining high milk production and there is no need to increase NDF concentration in diet when using barley grain as the grain source. In study 3, we evaluated the effects of supplementing a xylanase enzyme on production performance and nutrient digestibility of lactating dairy cows fed diets containing corn or sorghum silage as the forage source. We hypothesized that supplementing a xylanase enzyme product in diets containing corn or sorghum silage increases NDF digestibility, and production performance of lactating dairy cows would also be improved due to enhanced fiber digestion. Supplementation of xylanase for 19 d did not affect cow performance and nutrient utilization. Supplementation of xylanase may require a longer period of time to show any response in production performance and nutrient digestibility. We concluded that supplementing xylanase to cows fed corn or sorghum silage-based diets did not improve fiber digestion. But for feeding hulled or hulless barley grains to lactating dairy cows, increased NDF concentration in diets is not necessary and hulless barley is good as corn grain for feeding lactating dairy cows as the grain source. / Ph. D. / The overall objective of this study was to evaluate the effects of feeding hulless barley and supplementing a xylanase enzyme on production performance and nutrient utilization of lactating dairy cows. Barley starch is fermented faster than corn starch and can possibly reduce ruminal pH. Reduced ruminal pH can compromise cow production performance and cause some health problems. In study 1, we evaluated production performance, milk fatty acid composition, and nutrient digestibility in high-producing dairy cows consuming diets containing corn or hulless barley as the grain source. We hypothesized that a plausible reduction in production performance and milk fat percentage would be reduced by feeding hulless barley as the grain source in the diet. According to our results, the inclusion of hulless barley grain as the energy source in diets for lactating dairy cows resulted in similar production performance and nutrient utilization as corn grain. We concluded that hulless barley is as good as corn grain as an energy source and increasing fiber concentration in hulless barley-based diet is not necessary. In study 2, we evaluated production performance, nutrient digestibility, and milk fatty acid composition of high-producing dairy cows consuming diets containing hulled or hulless barley as the grain source. We hypothesized that rumen function is altered when cows are fed low-forage diets containing barley grains, and this altered rumen function would be reflected in lower production performance and a reduction of milk fat percentage. Contrary to our expectations, we did not observe any differences in cow production performance among all treatments. We concluded that both hulled or hulless barley grains are good energy sources for sustaining high milk production and there is no need to increase fiber concentration in diet when using barley grain as the grain source. In study 3, we evaluated the effects of supplementing a xylanase enzyme on production performance and nutrient digestibility of lactating dairy cows fed diets containing corn or sorghum silage as the forage source. We hypothesized that supplementing a xylanase enzyme product in diets containing corn or sorghum silage increases fiber digestibility, and production performance of lactating dairy cows would also be improved due to enhanced fiber digestion. Supplementation of xylanase for 19 d did not affect cow production performance and nutrient digestion. The effects of supplementation xylanase may require a longer period time to detect. We concluded that supplementing xylanase to cows fed corn or sorghum silage-based diets did not improve fiber digestion. For feeding hulled or hulless barley grains to lactating dairy cows, increased fiber concentration in diets is not necessary and hulless barley is good as corn grain for feeding lactating dairy cows as the grain source.

Fine tuning a nutritional strategy by incorporating dietary fibre (DF) in pig diets can help to improve gut health. Fermentation of DF, especially the soluble fraction, in pig intestines yields short-chain fatty acids (SCFA) and lactic acid, which have been found to improve gut health by favouring the growth of health-promoting bacteria such as <i>Lactobacilli</i> and <i>Bifidobacteria</i>, at the expense of pathogenic ones like <i>Clostridium</i> or <i>Salmonella</i>, which may enhance the health of host species. The presence of fermentable fibre in the pig diet can also contribute to reducing nitrogen (N) excretion, which can have a positive impact on the environmental footprint, one of the main concerns of a modern commercial pork production.<p> The overall objective of this thesis project was to evaluate the fermentation characteristics of a selection of feedstuffs in the pig intestines and their potential impact on the gut environment and nitrogen excretion. The evaluation was performed by executing two projects using both <i>in vitro</i> and in <i>vivo studies</i>.<p> The first project focused on the fermentation characteristics of hulless barley in comparison to hulled barley and oats and their effects on the gut environment, especially the production of fermentation metabolites. The rate of fibre fermentation in the intestines was first studied by means of an in vitro gas production technique. The results demonstrated that hulless barleys have higher fermentability and produce higher amounts of SCFA than hulled barley and oats. An experiment carried out on pigs confirmed that the fermentation of the soluble fibre fraction of hulless barley in the gut leads to increased production of SCFA and lactic acid, which in turn contribute to the growth of potentially beneficial microbiota and decrease potentially harmful bacteria, an indicator of improved gut health. This finding shows that gut health parameters may be modulated. Thus gut health could potentially be improved through feed formulation by a judicious selection of feed ingredients with specific fibre fractions, not only by the addition of isolated fibres, which is commonly recommended at present.<p> The second project was executed to study the effect of some feedstuffs differing in their DF and protein content on fermentation characteristics and N excretion in pigs. The feedstuffs included wheat bran, wood cellulose, peas, pea hulls, pea inner fibre, sugar beet pulp, flax seed meal and corn distiller's dried grains with solubles. The results showed that peas and pea fibre-based diets produced higher amounts of SCFA and reduced N excreted, compared to others. In a parallel <i>in vitro</i> study, fermentation characteristics and bacterial protein synthesis was also studied using the same feed ingredients. The findings of the <i>in vitro</i> study corraborated the results of the <i>in vivo</i> experiment. These studies showed that peas and pea fibres have the potential to be used in pig diets in order to gain gut health-benefits and reduce N excretion.<p> From this thesis, it can be concluded that sources and type of dietary fibre have a significant effect on the production of fermentation metabolites in the pig intestine and on N excretion. Among the feed ingredients studied, hulless barley and pea fibres seem to have the greatest potential to be included in pig diets as a source of fermentable fibre to modulate the gut environment, which in turn, extend possibly health-promoting properties and reduce N excretion from pigs. However, further research is needed to understand the specific health benefits of these fibre sources and to quantify the specific fibre components required to achieve these benefits.

Fine tuning a nutritional strategy by incorporating dietary fibre (DF) in pig diets can help to improve gut health. Fermentation of DF, especially the soluble fraction, in pig intestines yields short-chain fatty acids (SCFA) and lactic acid, which have been found to improve gut health by favouring the growth of health-promoting bacteria such as <i>Lactobacilli</i> and <i>Bifidobacteria</i>, at the expense of pathogenic ones like <i>Clostridium</i> or <i>Salmonella</i>, which may enhance the health of host species. The presence of fermentable fibre in the pig diet can also contribute to reducing nitrogen (N) excretion, which can have a positive impact on the environmental footprint, one of the main concerns of a modern commercial pork production.<p> The overall objective of this thesis project was to evaluate the fermentation characteristics of a selection of feedstuffs in the pig intestines and their potential impact on the gut environment and nitrogen excretion. The evaluation was performed by executing two projects using both <i>in vitro</i> and in <i>vivo studies</i>.<p> The first project focused on the fermentation characteristics of hulless barley in comparison to hulled barley and oats and their effects on the gut environment, especially the production of fermentation metabolites. The rate of fibre fermentation in the intestines was first studied by means of an in vitro gas production technique. The results demonstrated that hulless barleys have higher fermentability and produce higher amounts of SCFA than hulled barley and oats. An experiment carried out on pigs confirmed that the fermentation of the soluble fibre fraction of hulless barley in the gut leads to increased production of SCFA and lactic acid, which in turn contribute to the growth of potentially beneficial microbiota and decrease potentially harmful bacteria, an indicator of improved gut health. This finding shows that gut health parameters may be modulated. Thus gut health could potentially be improved through feed formulation by a judicious selection of feed ingredients with specific fibre fractions, not only by the addition of isolated fibres, which is commonly recommended at present.<p> The second project was executed to study the effect of some feedstuffs differing in their DF and protein content on fermentation characteristics and N excretion in pigs. The feedstuffs included wheat bran, wood cellulose, peas, pea hulls, pea inner fibre, sugar beet pulp, flax seed meal and corn distiller's dried grains with solubles. The results showed that peas and pea fibre-based diets produced higher amounts of SCFA and reduced N excreted, compared to others. In a parallel <i>in vitro</i> study, fermentation characteristics and bacterial protein synthesis was also studied using the same feed ingredients. The findings of the <i>in vitro</i> study corraborated the results of the <i>in vivo</i> experiment. These studies showed that peas and pea fibres have the potential to be used in pig diets in order to gain gut health-benefits and reduce N excretion.<p> From this thesis, it can be concluded that sources and type of dietary fibre have a significant effect on the production of fermentation metabolites in the pig intestine and on N excretion. Among the feed ingredients studied, hulless barley and pea fibres seem to have the greatest potential to be included in pig diets as a source of fermentable fibre to modulate the gut environment, which in turn, extend possibly health-promoting properties and reduce N excretion from pigs. However, further research is needed to understand the specific health benefits of these fibre sources and to quantify the specific fibre components required to achieve these benefits.