Dans son rôle « géo-accumulateur », le sol peut constituer un réservoir de Polluants Organiques Persistants (PoP). Les animaux élevés en plein air comme les ruminants laitiers peuvent alors être exposés aux PoP via l’ingestion involontaire de sol, un bovin adulte pouvant ingérer jusqu’à 800 g de sol par jour. Cependant, le mécanisme de sorption des PoP sur les particules du sol se caractérise par la formation de liaisons fortes susceptibles d’atténuer leur biodisponibilité. Afin de préciser le transfert des PoP du sol vers le ruminant, nous avons développé différentes approches permettant d’évaluer la biodisponibilité de ces contaminants. La chèvre en lactation a été choisie comme modèle de ruminant laitier.Les travaux se sont focalisés sur deux familles de composés : les Hydrocarbures Aromatiques Polycycliques (HAP) qui sont des molécules sensibles au métabolisme, et les PolyChloroBiphenyles (PCB), peu sensibles au métabolisme. Pour les PCB, la biodisponibilité relative a été obtenue en comparant les coefficients de transfert ou « Carry-Over Rate » obtenus à la suite de l’ingestion de sol avec ceux trouvés dans la littérature impliquant des matrices alimentaires telles que le foin. Cette valeur, obtenue à l’équilibre, désigne la part fixe du contaminant atteignant le lait. La seconde expérience a été élaborée afin de calculer la biodisponibilité relative des HAP liés au sol. Cette démarche s’est basée sur la comparaison des pentes des courbes doses-réponses obtenues entre l’ingestion de la matrice sol ou de la matrice de référence (l’huile) et l’excrétion des métabolites de HAP hydroxylés majoritaires dans les urines. La dernière étude a consisté en une collecte de données de la littérature, dans le but de déterminer globalement le rôle de la matière organique (carbone organique) du sol sur la bioaccessibilité des HAP dans le tractus gastro-intestinal. Les résultats des études que nous avons menées démontrent que le sol a un impact limité sur la biodisponibilité orale de l’ensemble des PoP chez le ruminant. Cependant, la lipophilicité des PoP semble jouer un rôle dans la régulation de leur biodisponibilité. En effet, l’impact du sol sur la biodisponibilité du Phénanthrène est limité (molécule à trois cycles), tandis que la réduction de la biodisponibilité du Pyrène a été estimée à 50 % (molécule à quatre cycles).Du plus, la bioaccessibilité dans le tractus digestif (une des composantes de la biodisponibilité) a été estimée pour les HAP : elle varierait entre 0,2 et 46%, et serait guidée par la concentration des HAP et la teneur en carbone organique du sol. L’effet géosorbant du sol, qui explique son rôle de réservoir environnemental de PoP, paraît insuffisant dans les conditions du tractus digestif du ruminant laitier, pour éviter une contamination des produits animaux. Une attention particulière doit être portée au sol dans les scénarios d’évaluation du risque / Persistent Organic Pollutants (PoP) can be accumulated through the “memory effect of soil”. Ruminants can therefore be exposed to the PoP through involuntary ingestion of the contaminated soil. On pasture, soil ingested by ruminants can reach 800 g of soil per day. But PoP interact with the soil particles, leading to the formation of strong bonds which can decrease their bioavailability. Therefore, we developed several approaches in order to determine the bioavailability of soil-bound PoP. Indeed, more precision on the impact of soil on the bioavailability of the contaminants is essential to assess the transfer to the animal products. The investigations focused on two PoP families: the Polycyclic Aromatic Hydrocarbons (PAH) which are readily cleared and the PolyChloroBiphenyls (PCB) which are poorly metabolized. For the PCB, the relative bioavailability was estimated by comparing the values of the transfer coefficients or « Carry-Over Rates » obtained after soil ingestion, with that those obtained in the literature with other food matrices such as hay. The second study was conducted in order to calculate the bioavailability of soil-bound PAH. This experimental approach lay in comparing soil matrix with the reference matrix (oil) through the urinary excretion of the major hydroxylated PAH metabolites. The last investigation focused on the statistical combination of the results of several studies that address a set of related research on the role of organic matter (organic carbon) on the bioaccessibility of the PAH in the gastro-intestinal tract. The results of the studies performed show that soil has limited impact on the PoP bioavailability in ruminants. However, the lipophilicity of PoP seems to play a role in regulating their bioavailability. Indeed, soil impact is not significant for Phenanthrene (three-ring molecule), whereas the bioavailability of Pyrene is estimated at 50 % (four-ring molecule). The bioaccessibility in the gastro-intestinal tract is a component of the bioavailability; it was estimated for PAH at between 0.2 and 46%, and seems to be led by the concentration of PAH and the organic carbon content in soil. These results suggest that soil matrix deserves some special focus because its properties of geoaccumulation may increase the risk of transfer of PoP to the ruminant. The geosorbant property of soil, which explains its role as environmental reservoir of PoP, does not appear enough to avoid contamination of animal products, in the conditions of the lactating ruminant digestif tract. Particular attention should be paid to soil in the scenarios of risk assessment

Les infestations par les strongles gastro-intestinaux (SGI) constituent une cause majeure de morbidité et de mortalité chez les petits ruminants élevés au pâturage et entraînent donc des pertes de production. En raison de l'émergence de la résistance aux anthelminthiques et des préoccupations des consommateurs concernant les résidus chimiques dans les produits animaux, des stratégies alternatives de contrôle sont nécessaires. L'objectif n'est plus l'éradication totale de la population parasitaire, mais plutôt un meilleur contrôle de ces populations pour atteindre un équilibre favorable à la production animale entre l'hôte et les parasites. Une stratégie prometteuse pour le contrôle des SGI est l'amélioration de la réponse de l'hôte par le statut nutritionnel des animaux. Bien que les chèvres soient plus sensibles que les moutons aux infestations par les NGI, la plupart des programmes de recherche visant à caractériser les interactions hôtes-NGI est menée chez les ovins. Contrairement à l’idée que les résultats acquis chez le mouton seraient applicables aux chèvres du fait de leur proximité, de nombreuses études soulignent des différences significatives entre ces modèles. L’objectif de ce travail de thèse était d’étudier l’impact du statut nutritionnel en termes de quantité de protéines et d’énergie et de la qualité des protéines apportée par la ration sur les réponses (production vs réponse contre le parasitisme) de caprins Créole infestés expérimentalement par Haemonchus contortus. Nous avons montré que le statut nutritionnel permettait de réduire la sévérité et la durée de l’anémie régénérative et de la thrombopénie induite par H. contortus chez le caprin Créole. La ration enrichie en protéines était associée à de la résilience vis-à-vis de l’infestation plutôt que de la résistance. / Gastrointestinal nematode (GIN) infections are a major cause of morbidity and mortality in small ruminants at pasture and therefore lead to production losses. Due to the emergence of anthelmintic resistance and consumer concerns about chemical residues in animal products, alternative control strategies are needed. The objective is no longer the total eradication of the parasite population, but rather a better control of these populations to achieve a favorable balance between the host and the parasites to improve animal production. A promising strategy for NGI control is to improve the host response through the nutritional status of the animals. Although goats are more susceptible than sheep to NGI infestations, most research programs to characterize host-NGI interactions are conducted in sheep. In contrast with the idea that the results obtained in sheep will be applicable to goats because of their proximity, many studies highlight significant differences between these models. The objective of this research project was to study the impact of nutritional status in terms of protein and energy quantity and protein quality provided by the diet on the responses (production vs response against parasitism) of Creole goats experimentally infested by Haemonchus contortus. We have shown that nutritional status reduces the severity and duration of regenerative anemia and H. contortus-induced thrombocytopenia in Creole goats. The protein-enriched diet was associated with resilience to infection rather than resistance

11 pp. / This publication contains information about browse utilization by ruminant animals. It provides information about the rangelands in Arizona, the nutritional quality of browse, effects of drought and tannin and how to overcome them.

A intensificação do sistema de produção da carne ovina é influenciada por algumas técnicas de manejo como a castração e o sistema de confinamento, tendo como objetivo produto de melhor qualidade sensorial e nutricional desejada pelo consumidor e maior rentabilidade para o produtor. Portanto, objetivou-se com este trabalho avaliar desempenho, características de carcaça e da carne, qualidade sensorial e perfil de ácidos graxos da carne de cordeiros não castrados e castrados abatidos em diferentes períodos de confinamento. Foram utilizados 48 machos Dorper x Santa Inês com 32,3 ± 5,04 kg de peso corporal e 104 dias de idade no início do experimento. Os animais foram alojados dois por baia de acordo com o peso inicial (bloco) e após 14 dias de adaptação ao local foram alimentados com uma dieta com 75% grão de milho inteiro, 20% de pelete protéico mineral e 5% de feno de capim coast cross. Os animais foram desmamados aos 90 dias de idade e após a adaptação vinte e quatro animais foram castrados com o burdizzo aos 113 dias de idade. A alimentação e as sobras foram pesadas diariamente para determinações de matéria seca e eficiência alimentar. Os animais foram pesados no início do experimento e a cada 14 dias. Foram perdidas duas parcelas experimentais. Os animais foram abatidos após 36 ou 78 dias de confinamento (metade de cada sexo) para determinação das características da carcaça e da carne e foram colhidas amostras do m. Longissimus dorsi para análise do perfil de ácidos graxos e análise sensorial com painel treinado. Em vista dos resultados obtidos para cordeiros jovens desse tipo de cruzamento e alimentados com esta dieta, os animais não castrados tiveram melhor desempenho, características de carcaça e de carne que os castrados, já na qualidade sensorial poucos resultados foram significativos enquanto que no perfil de ácidos graxos houve efeitos e interações entre a condição sexual e o tempo de confinamento, indicando que animais castrados abatidos aos 36 dias tiveram um carne mais magra, com maior porcentagem de n-3 e relação AGP:AGS. / The intensification of the production system of sheep meat is influenced by some management techniques such as castration and confinement system, aiming to produce better sensory and nutritional quality desired by consumers and more profitable for the producer. Therefore, the aim of this study was to evaluate performance, carcass characteristics and meat sensory quality and fatty acid profile of lamb meat from non-castrated and castrated slaughtered at different periods of confinement. We used 48 male Dorper x St. Agnes with 32.3 ± 5.04 kg body weight and 104 days old at the start of the experiment. The animals were housed two per cage according to the initial weight (block) and after 14 days of adaptation to site were fed a diet containing 75% whole grain corn, 20% protein pellet mineral and 5% grass hay Coast cross. The animals were weaned at 90 days of age and after adjustment twenty-four animals were castrated with burdizzo to 113 days of age. The food and leftovers were weighed daily for determinations of dry matter and feed efficiency. The animals were weighed at baseline and every 14 days. We lost two experimental plots. The animals were killed after 36 or 78 days of confinement (half of each sex) to determine the characteristics of the carcass and meat and samples were taken from m. Longissimus for analysis of fatty acid profile and sensory evaluation with trained panel. In view of the results obtained for young lambs this type of intersection and fed this diet, the animals were not castrated best performance, carcass characteristics and meat castrated, have sensory quality were few significant results while in acid profile acids were effects and interactions between the sexual condition and the time of confinement, indicating that castrated animals slaughtered at 36 days had a more lean meat, with higher n-3 and relationship AGP: AGS.

A emissão de gases de efeito estufa (GEE) é uma das principais causas do aquecimento global, sendo uma problemática mundial das últimas décadas. O dióxido de carbono (CO2), o metano (CH4) e oxido nitroso (N2O) são os principais GEE e os ruminantes são uns dos maiores contribuintes com a produção desses gases no mundo, devido ao processo digestivo de fermentação entérica. Na busca de estratégias para diminuir as emissões de metano e melhorar a produtividade animal, aditivos alimentares têm sido utilizados nas dietas dos animais. Assim, o objetivo deste trabalho foi avaliar a inclusão de aditivos alimentares sobre a produção de metano determinada pela técnica do gás traçador SF6, assim como, o consumo de matéria seca, a dinâmica ruminal e a contagem total e diferencial de protozoários do rúmen. Seis vacas não-gestantes e não-lactantes, com peso vivo médio de 784 ± 87 kg e canuladas no rúmen, foram distribuídas a uma das três dietas experimentais, seguindo-se delineamento experimental em quadrado latino 3x3 replicado (n= 18 unidades experimentais), sendo os tratamentos: 1) Controle (CON): Dieta basal sem inclusão de aditivo; 2) Monensina (MON): Dieta com adição de 300 mg de monensina sódica por animal por dia; 3) Tanino (TAN): Dieta com adição de 68 g de extrato de tanino condensado de Acácia-negra (Acacia mearnsii) por animal por dia. Os alimentos foram fornecidos duas vezes ao dia, na forma de ração completa. Cada período experimental foi constituído por 21 dias, sendo 10 dias de adaptação às respectivas dietas. A partir do dia 16 até o dia 21 foram coletados os dados de consumo de matéria seca e de produção de metano, sendo este último determinado a cada 24 horas, pela técnica do gás traçador de SF6. No dia 21, coletou-se conteúdo ruminal para determinação de protozoários. Quanto à dinâmica ruminal, foi realizado o esvaziamento ruminal nos dias 10 (3 horas após alimentação matinal) e 11 (imediatamente antes da alimentação matinal) de cada período experimental. Os resultados foram analisados através do procedimento MIXED onde o modelo incluiu o efeito de tratamento como fator fixo e os efeitos de animal dentro de quadrado, quadrado e período como fatores aleatórios. Não houve diferenças significativas (P>0,05) entre os tratamentos para as variáveis do consumo de matéria seca, como também, para os parâmetros de dinâmica ruminal (P>0,05) (matéria seca do conteúdo ruminal, massa líquida, massa sólida, massa total, assim como taxa de desaparecimento). A emissão de metano (expressa em g/d, g/kg PV, g/kg PV0,75 ou Mcal/Ani/d) com o tratamento com monensina foi menor em relação ao tratamento controle. Para a contagem total e diferencial de protozoários foi verificado efeito de aditivo para a subfamília Diplodiniinae, sendo que, o tratamento com monensina diminuiu em 27,5% a contagem desta subfamília em relação ao tratamento com tanino. Referente ao gênero Isotricha, foi observado que os tratamentos com monensina ou com tanino diminuíram em 31 e 30% respectivamente, este gênero em relação ao tratamento controle. A adição de monensina (17 mg/kg de MSI) revela-se uma alternativa para reduzir as perdas energéticas geradas na produção de metano, assim como também na redução de protozoários, que albergam microrganismos metanogênicos. Em relação ao tanino (0,4% na dieta) acredita-se que com doses mais elevadas na dieta possa resultar numa redução da emissão de metano / The emission of greenhouse gases (GHG) is a major cause of global warming, being a worldwide concern in recent decades. Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are the main greenhouse gases and ruminants are one of the major contributors to the production of these gases around the world, due to the enteric fermentation process. In the search for strategies to reduce methane emissions and to improve animal productivity, food additives have been used in animal diets lately. Thus, the aim of this trial was to assess the inclusion of food additives on methane emissions in cattle, using the sulfur hexafluoride (SF6) tracer technique, as well as on dry matter intake, rumen dynamics and total and differential counts of ruminal protozoa. Six non-pregnant and non-lactating rumen-cannulated cows (784 ± 87 kg) were assigned to a replicated 3x3 Latin square (18 experimental units). Treatments were: 1) Control (CON) basal diet with no additive inclusion; 2) Monensin (MON) addition of 300 mg of sodium monensin per animal per day, 3) Tannin (TAN) addition of 68 g of concentrated extract of condensed tannin (Acacia mearnsii) per animal per day. The animals were fed total mixed ration twice daily. Each experimental period consisted of 21 days the first 10 days were used for diet adaptation. From day 16 up to 21, data about dry matter intake and methane production were collected, the latter done every 24 hours using the sulfur hexafluoride (SF6) tracer technique. On the day 21, ruminal content was sampled for protozoa determination. Regarding the rumen dynamics, the rumen was emptied on days 10 (3 hours post-morning feeding) and 11 (right before morning feeding) of each experimental period. The results were analyzed by MIXED procedure; the model included the effect of treatment as fixed factor and the effects of period, square and animal within square as random factors. There were no significant differences (P>0.05) among treatments for dry mater intake variables, nor for ruminal dynamics parameters (ruminal content dry matter, liquid mass, solid mass, total mass or disappearance rate). Methane emission (expressed in g/day, g/kg LW, g/kg LW0.75 or Mcal/Ani/day) was lower for the group receiving monensin compared to the control group. For total and differential counts of protozoa, the additives affected the Diplodiniinae subfamily, i.e. monensin decreased the count of this subfamily by 27.5%, compared to tannin. Regarding the Isotricha genus, treatments with monensin or tannin decreased it by 31 and 30% respectively, compared to the control treatment. The addition of monensin (17 mg/kg DMI) revealed to be an alternative to reduce the energy lost by methane production, as well as to decrease the protozoa, which host methanogen microorganisms. Regarding tannin (0.4% in the diet), it is believed that higher doses in the diet can lead to a reduction in methane emission

Protein is an important fraction within bovine milk. This milk protein is not only vital for calf growth and development, but also includes bioactive proteins and peptides that have been shown to enhance the health of animals and humans. Research efforts are focusing on factors, such as nutrition, that can influence the quantity and profile of proteins within the bovine milk proteome. The research outlined herein investigated the impact of diet on the bovine milk proteome. The first experiment examined whether dietary inclusion of grape marc (GM), a condensed tannin (CT) containing by-product from the viticulture industry, could alter the bovine milk proteome through altered nitrogen (N) metabolism. In this experiment, 10 lactating Holstein cows were fed either 2.0 kg dry matter (DM)/ cow/ day of beet pulp: soy hulls in a 50% mixture (control), or 1.5 kg DM/ cow/ day of GM as part of a balanced dairy cow ration for a 28-d trial. Milk samples were obtained for analysis of the high- and low-abundance protein fractions. Skimmed milk samples collected for high-abundance protein analysis were measured using high performance liquid chromatography (HPLC), and liquid-chromatography tandem mass spectrometry (LC-MS/MS) was used to identify proteins in the low-abundance protein enriched fraction. Skimmed milk samples collected for low-abundance milk protein analysis were fractionated and enriched to remove higher abundance proteins. Enriched milk samples were then digested and labeled with isobaric tandem mass tags (TMT) prior to protein identification using LC-MS/MS analysis. There were no changes in the high-abundance protein fraction in response to diet; however, 16 of 127 low-abundance proteins were identified at different relative-abundances due to diet (P ≤ 0.05). While there were no alterations in the metabolic or N status of animals due to GM supplementation, the 12% change in the low-abundance milk protein fraction highlighted the potential for dietary alteration of the bovine milk proteome. A second experiment evaluated the inclusion of alternative forage crops (AFC) as a means to alter the bovine milk proteome. In this experiment, both the skimmed milk and milk fat globule membrane (MFGM) protein fractions were included in analysis. Milk samples were collected from 16 lactating Jersey cattle included in a 21-d grazing experiment, where cows were offered one of two diets. The control group (CON, n=8) grazed a grass-legume pasture mixture containing orchardgrass (Dactylis glomerata), timothy (Phleum pratense), Kentucky bluegrass (Poa pratensis), and white clover (Trifolium repens). The treatment group (AFC, n=8) grazed a similar base pasture that was strip-tilled with oat (Avena sativa), buckwheat (Fagopyrum esculentum), and chickling vetch (Lathyrus sativus) so that the AFC species comprised 10% of the AFC group’s pasture DM intake (DMI). Milk samples were collected for HPLC analysis of the high abundance milk proteins, and LC-MS/MS analysis of the low abundance protein enriched skim milk fraction and MFGM-associated protein fraction. Cows that grazed pastures containing AFC had higher αs1-CAS content (P = 0.005), and higher relative-abundances of 7 low-abundance proteins within the skim milk and MFGM fractions (P ≤ 0.05). While it is plausible that the inclusion of AFC in pasture increased nutrient availability to the mammary gland, the specific mechanisms that could have caused the shifts observed remain unclear. Further investigation is necessary to fully understand the role of diet and the milk protein profile.

Les réponses nutritionnelles et zootechniques des ruminants aux variations de régime sont largement conditionnées par leurs effets au niveau du rumen. L'objectif de ce travail était d'apporter de nouvelles perspectives pour progresser dans la démarche de modélisation de cet organe, qui a débuté dans les années 1970. Pour l'aborder, nous avons privilégié une approche par modélisation systémique à différents niveaux organisationnels: de l'organe, aux flux de nutriments et jusqu'aux mécanismes de régulation cellulaire. La première partie du travail était consacrée à une étude comparative des modèles actuels. Peu de validations comparées des modèles avaient été entreprises jusqu'à présent. Les résultats rendent compte des principes communs appliqués mais aussi des spécificités de chacun des modèles. Leur plus grande faiblesse réside dans leur incapacité à prédire de façon satisfaisante les équilibres des produits terminaux des fermentations (acides gras volatils, gaz et matières microbiennes). Pour progresser dans ce domaine, nous avons exploré deux voies. La première concerne la représentation de la digestion de l'amidon, substrat glucidique expliquant la majeure partie des variations de la vitesse de digestibilité ruminale des rations. Nous avons développé un modèle de prédiction des flux d'amidon pour mieux quantifier et expliquer les variations observées. Cette étude a été réalisée à partir de bases de données quantitatives portant sur ces flux mesurés in sacco et in vivo. Les résultats obtenus expliquent assez précisément les variations observées intra-essai. Par contre, les variations inter-essais demeurent importantes et difficiles à apprécier. La seconde voie est basée sur l'application des lois de la thermodynamique au métabolisme microbien. L'objectif est d'améliorer la prédiction des produits terminaux des fermentations. Cette approche originale des aspects fermentaires a comporté un volet modélisation et un volet expérimental. Les résultats permettent de dégager certaines propriétés comme résultant des principes de la thermodynamique et nous confortent dans l'intérêt de cette approche. Ce travail de thèse contribue aux avancées en matière de modélisation du rumen, notamment pour la modélisation des flux d'amidon. Il propose aussi de nouveaux champs de recherche encore peu explorés.

Barley grain is an important source of energy and protein for ruminant animals. However, feeding must be carefully managed to avoid maladies caused by the rapid breakdown of barley starch in the rumen. The development of slower degrading barley for ruminants may alleviate health problems associated with barley grain consumption. Selection for hard endosperm may result in slower starch degradation and improved feed quality. The objectives of this study were to: examine the effect of grain hardness, variety and environment on dry matter disappearance rate (DMDR); identify accurate and efficient hardness selection tools; and study environmental effects, inheritance and heritability of hardness.<p>To study grain hardness and genetic and environmental effects on DMDR, two genotypes grown at multiple locations in 2004 were analyzed for Single Kernel Characterization System (SKCS) hardness, by scanning electron microscopy (SEM), and for in situ DMDR. Genotype by environment interaction influenced DMDR, while neither SKCS hardness nor SEM analysis accurately differentiated DMDR between genotypes. <p>Eight genotypes were grown at multiple locations during 2003 and 2004 to study grain hardness measurement methodology, and genetic and environmental effects on hardness. Genotypes were analyzed for SKCS hardness, milling energy, endosperm light reflectance, feed particle size, protein and beta-glucan. Hardness measurements ranked genotypes similarly across environments. Feed particle size was correlated with milling energy but not other hardness measurements. Hardness measurements appeared to be influenced by protein and beta-glucan.<p>To examine the inheritance and heritability of barley grain hardness, 245 double haploid (DH) genotypes and parents, grown in 2003 and 2004, were analyzed for SKCS hardness, milling energy, protein, beta-glucan, with 100 evaluated for light reflectance. The population exhibited normal distributions for SKCS hardness, milling energy, protein and beta-glucan, suggesting quantitative inheritance for these traits with no apparent epistatic gene interaction. Narrow-sense heritability was 0.75 for SKCS hardness and 0.41 for protein. Light reflectance was not normally distributed, suggesting complementary gene interaction. Broad-sense heritability was 0.53.<p>Barley grain hardness is highly heritable and an efficient tool in making selections in a breeding program. However, breeding for high beta-glucan and protein may be better selection criteria for indirect selection of DMDR.

Barley grain is an important source of energy and protein for ruminant animals. However, feeding must be carefully managed to avoid maladies caused by the rapid breakdown of barley starch in the rumen. The development of slower degrading barley for ruminants may alleviate health problems associated with barley grain consumption. Selection for hard endosperm may result in slower starch degradation and improved feed quality. The objectives of this study were to: examine the effect of grain hardness, variety and environment on dry matter disappearance rate (DMDR); identify accurate and efficient hardness selection tools; and study environmental effects, inheritance and heritability of hardness.<p>To study grain hardness and genetic and environmental effects on DMDR, two genotypes grown at multiple locations in 2004 were analyzed for Single Kernel Characterization System (SKCS) hardness, by scanning electron microscopy (SEM), and for in situ DMDR. Genotype by environment interaction influenced DMDR, while neither SKCS hardness nor SEM analysis accurately differentiated DMDR between genotypes. <p>Eight genotypes were grown at multiple locations during 2003 and 2004 to study grain hardness measurement methodology, and genetic and environmental effects on hardness. Genotypes were analyzed for SKCS hardness, milling energy, endosperm light reflectance, feed particle size, protein and beta-glucan. Hardness measurements ranked genotypes similarly across environments. Feed particle size was correlated with milling energy but not other hardness measurements. Hardness measurements appeared to be influenced by protein and beta-glucan.<p>To examine the inheritance and heritability of barley grain hardness, 245 double haploid (DH) genotypes and parents, grown in 2003 and 2004, were analyzed for SKCS hardness, milling energy, protein, beta-glucan, with 100 evaluated for light reflectance. The population exhibited normal distributions for SKCS hardness, milling energy, protein and beta-glucan, suggesting quantitative inheritance for these traits with no apparent epistatic gene interaction. Narrow-sense heritability was 0.75 for SKCS hardness and 0.41 for protein. Light reflectance was not normally distributed, suggesting complementary gene interaction. Broad-sense heritability was 0.53.<p>Barley grain hardness is highly heritable and an efficient tool in making selections in a breeding program. However, breeding for high beta-glucan and protein may be better selection criteria for indirect selection of DMDR.

At present, the United States generates biofuels (ethanol) from corn grain. Unfortunately, low crop yields and limited growth regions result in limited availability. Furthermore, the use of staple food crops for ethanol production has generated a highly controversial food vs. fuel debate. Because of its high abundance and relatively low cost, lignocellulosic biomass is a promising alternative feedstock for biofuel production; however, structural features of lignocellulose limit accessibility of enzymes or microorganisms. These structural barriers include high lignin content, acetyl groups on hemicellulose, high cellulose crystallinity, cellulose degree of polymerization, and small pore volume. To overcome these barriers, a variety of pretreatment processes (chemical and mechanical) have been developed. Oxidative-lime pretreatment (OLP) is highly effective at reducing lignin content and removing acetyl groups from hemicellulose. Combining OLP with a mechanical treatment process greatly enhances the enzymatic digestibility of lignocellulose. Recommended OLP conditions were determined for Dacotah (120 °C, 6.89-bar O2, 240 min) and Alamo (110 °C, 6-89-bar O2, 240 min) switchgrass. Using recommended conditions, 72-h glucan digestibilities (g glucan hydrolyzed/100 g glucan in raw biomass; 15 filter paper units/g raw glucan) of 85.2 and 88.5 were achieved for Dacotah and Alamo, respectively. Adding ball milling to OLP further enhanced glucan digestibility to 91.1 (Dacotah) and 90.0 (Alamo). In previous studies, shock treatment achieved promising results, but was often inconsistent. This work refined shock treatment with a focus on using consistent procedures and performance analysis. The combination of OLP and shock treatment enhanced the 72-h glucan digestibility of several promising biomass feedstocks: bagasse (74.0), corn stover (92.0), poplar wood (94.0), sorghum (71.8), and switchgrass (89.0). Highly digestible lignocellulose can also be used as ruminant animal feed. Shock treatment plus OLP increased the total digestible nutrients (TDNN; g nutrients digested/100 g organic matter) of corn stover from 51.9 (untreated) to 72.6. Adding in pre-washed corn stover solubles to produce a combined feed (17.8 percent corn stover solubles and 82.2 percent shock OLP corn stover) increased TDNN to 74.9. Mixing in enough solubilized protein to match the crude protein content of corn grain further improved TDNN to 75.5, only 12.6 less than corn grain.