P. 1999. Prediction of composition and ruminal degradability characteristics of barley straw by near infrared reflectance spectroscopy. Can. J. Anim. Sci. 79: 519-523. The usefulness of near infrared reflectance spectroscopy (NIRS) for the prediction of the nutritive value of straw was examined with 195 samples of barley straw. Excluding lignin, NIRS technique explained 84 to 94% of the variation in chemical components in the validation set. From 69 to 84% of the variation in ruminal degradability characteristics, excluding rate of degradation, was explained by NIRS. With the exception of neutral detergent fiber, accuracies of prediction were not improved when NIRS calibrations were based upon calibration sets containing straw only in contrast with when barley hay and barley silage were included with straw in the calibration set. We conclude that near infrared reflectance spectroscopy is a useful method for predicting chemical composition of straw and estimating its ruminal degradability characteristics.Key words: Barley, straw, near infrared reflectance spectroscopy, in situ, degradability Mathison, G. W., Hsu, H., Soofi-Siawash, R., Recinos-Diaz, G., Okine, E. K., Helm, J. et Juskiw, P. 1999. Prédiction de la composition et de la dégradabilité ruminale de la paille d'orge par spectrométrie de réflectance dans le proche infrarouge. Can. J. Anim. Sci. 79: 519-523. Nous avons observé sur 195 échantillons de paille l'utilité de la spectrométrie de réflectance dans le proche infrarouge (SPIR) pour la prédiction de la valeur nutritive de la paille d'orge. Sauf pour la lignine, la technique SPIR rendait compte de 94 % de la variation affectant les composants chimiques des échantillons de validation. En outre, elle expliquait de 69 à 84 % de la variation des paramètres de dégradabilité ruminale,sauf le taux de dégradation. À l'exception de la teneur en FDN, le degré de précision des prédictions n'était pas amélioré lorsque les calibrations SPIR étaient basées sur le jeu d'échantillonsde calibration ne contenant que de la paille seule plutôt qu'un mélange de paille et de foin et d'ensilage d'orge. La spectrométrie de réflectance dans le proche infrarouge se présente donc comme une méthode intéressante pour prédire la composition chimique de la paille et pour estimer ses paramètres de dégradabilité dans le rumen. Mots clés:Orge, paille, SPIR, spectrométrie de réflectance dans le proche infrarouge, in situ, dégradabilitéThe majority of wintering beef cow diets in Western Canada contain straw as a result of direct inclusion in rations or because cows obtain it by eating bedding. Methods for measurement of nutritive value of straw are important since it varies in its nutritive value (Mathison et al. 1999). The in situ procedure has been widely used to estimate the nutritive value of feeds for ruminant animals. von Keyserlingk and Mathison (1989) reported that up to 86 and 92% of the variation in voluntary dry matter (DM) intake and digestibility, respectively, could be explained by differences in in situ degradation chara...

P. 1999. Factors influencing composition and ruminal degradability of barley straw. Can. J. Anim. Sci. 79: 343-351. Chemical composition and in situ ruminal degradability characteristics for 25 and 40 genotypes of barley straw were measured for crops grown in 1994 and 1995, respectively. Straw from semidwarf genotypes contained more crude protein and less neutral detergent fiber (NDF) than that from genotypes with medium straw length and effective ruminal degradability was 9% higher (P < 0.01). Straw from two-row genotypes contained 19% more crude protein (4.4 vs. 3.7%) and 3% less NDF (75.2 vs. 77.6%) than that from six-row genotypes and effective ruminal degradability was 6% higher (P < 0.01) when genotypes with medium-length straw only were considered. Genotypes with smooth awns had higher rates of degradation but contained less of the slowly degraded fraction than straw with rough awns when straws of medium straw length were compared (P < 0.05). Straw from hulless genotypes contained more (P = 0.006) NDF than that from covered varieties. Both ambient and soil temperature were positively related (P < 0.05) to effective ruminal degradability of straw, possibly because of associated greater leafiness when temperatures were higher and there was more light. It was concluded that it is possible to select barley genotypes that have superior straw nutritive value for ruminant animals. (FDN) que celle des géno-types à paille de longueur moyenne et leur dégradabilité ruminale effective était de 9 % plus élevée (P < 0,01). La paille des géno-types à deux rangs renfermait 19 % de plus de protéines brutes (4,4 contre 3,7 %) et 3 % moins de FDN (75,2 contre 77,6 %) que celle des lignées à six rangs, avec une dégradabilité ruminale de 6 % plus forte (P < 0,01) lorsqu'on ne comparait que des géno-types à paille de longueur intermédiaire. Toujours dans le même groupe de longueur de paille, les orges à barbes lisses manifestaient des taux plus élevés de dégradation mais ils contenaient une moindre quantité de la fraction à dégradation lente que les orges à barbes rugueuses (P < 0,05). La paille des orges à grain nu contenait plus de FDN que celle des variétés à grain vêtu. On observait une corrélation positive (P < 0,05) entre la température de l'air et celle du sol, d'une part, et la dégradabilité ruminale effective de la paille,d'autre part, sans doute à cause du feuillage plus abondant lorsque les températures étaient plus hautes et qu'il y avait plus de lumière dans le couvert végétal. Il apparaît donc possible de sélectionner de meilleurs génotypes d'orge de valeur nutritive supérieure pour les ruminants.

-Siawash, R. 2004. Frequency of concentrate supplementation for cattle fed barley straw. 1. Effect on voluntary intake, ruminal straw disappearance, apparent digestibility and heat production. Can. J. Anim. Sci. 84: [455][456][457][458][459][460][461][462][463][464][465]. Five ruminally cannulated crossbred steers (474 ± 30 kg) were fed diets containing 70% barley straw and 30% concentrate in an unbalanced 5 × 5 Latin square design experiment to investigate the effects of frequency of feeding barley grain-based concentrates (daily, alternate days or every third day) with different dietary protein (7.9 and 11.5%) on voluntary intake of straw, ruminal disappearance of straw, apparent digestibility, and heat production. Neither frequency of feeding nor dietary protein concentration influenced voluntary intake of straw, nor did cattle eat differing amounts of straw on days when concentrate was fed in comparison with days when concentrate was not fed. Protein supplementation increased (P < 0.01) 24-h ruminal straw disappearance, but did not affect disappearances at other times. Concentrate feeding frequency had no influence on rate of ruminal disappearance of straw. Apparent digestibilities of dry matter, gross energy, acid detergent fibre (ADF) and crude protein were 5, 6, 8 and 33% higher (P < 0.05), respectively, in diets containing the high-protein concentrate, but were not affected by frequency of concentrate feeding. Heat production (kJ kg -0.75 ) tended to be reduced (P = 0.06) by 4% in steers fed concentrate on alternate days in comparison with steers fed concentrate daily. Dietary protein concentration had no influence on heat production even though digestible energy intake was 10% higher when the high protein concentrate diet was fed. It was concluded that concentrate can be fed every second day without any negative impact on intake and digestibility, with a possible benefit of a reduction in energy lost as heat. More research, however, is required to study the feasibility of feeding concentrate every third day.Key words: Cattle, straw, protein, feeding frequency, digestion, heat production Tellier, R. C., Mathison, G. W., Okine, E. K., McCartney, D. et Soofi-Siawash, R. 2004. Fréquence des apports de concentré pour les bovins nourris de paille d'orge. 1. Incidence sur l'indice de consommation, la disparition de la paille dans le rumen, la digestibilité apparente et la production de chaleur. Can. J. Anim. Sci. 84: 455-465. Cinq bouvillons hybrides (474 ± 30 kg) canulés au rumen ont reçu un régime composé à 70 % de paille d'orge et à 30 % de concentré dans le cadre d'une expérience en carré latin 5 × 5 non équilibré qui devait préciser les effets de la fréquence à laquelle un concentré d'orge à teneur variable en protéines (7,9 et 11,5 %) était servi (tous les jours, un jour sur deux ou aux trois jours) sur l'indice de consommation de la paille, la disparition de cette dernière dans le rumen, la digestibilité apparente et la production de chaleur. Ni la fréquence ni la concentration de protéines n'ont d'inf...

A 2 × 3 factorially designed experiment with 216 bull calves (288 ± 43 kg) was conducted in which tempered and dry barley grains were lightly rolled (most of kernels cracked, few broken), medium rolled, or crushed (almost all kernels broken) and included in a feedlot diet containing 90% concentrate and 10% barley silage on a dry matter (DM) basis. In the tempering process 6% water was added to the control barley, which initially contained 13% moisture, and the damp grain was allowed to stand overnight at room temperature before rolling. Tempering had no influence on rate or efficiency of gain of the bulls during the 134-d trial or on carcass characteristics. Cattle fed slightly rolled, medium rolled, and crushed barley (kernel thicknesses of 2.70, 2.56 and 2.31 mm) gained 1.55, 1.57 and 1.61 kg d−1, respectively, with no difference detected between treatments. Corresponding DM intakes were 8.04, 7.79 and 7.54 kg d−1 (P < 0.05). Dry matter intake to gain ratios were 5.20, 4.96 and 4.68 (P < 0.05). Carcasses of bulls fed crushed barley had more (P < 0.05) grade fat than bulls fed slightly rolled barley. It was concluded that there was no advantage in tempering barley which initially contained 13% moisture. Efficiency of gain was improved as the degree of processing of barley was increased. Key words: Bulls, barley, tempering, processing, gain, feed efficiency

. Degradability of alfalfa saponins in the digestive tract of sheep and their rate of accumulation in rumen fluid. Can. J. Anim. Sci. 79: 315-319. Two experiments were conducted to examine the fate of alfalfa saponins in the digestive tract of sheep. In the first experiment 14.4 or 28.8 g saponins were administered intraruminally daily, which provided 62 and 78% of the total saponin entering the rumen. Degradabilities of the saponins in the total digestive tract were 96.0 and 97.9% (P = 0.13), respectively, but no attempt was made to determine how closely the products of degradation were related to the original molecules. In the second experiment, the rate of release of saponins from alfalfa into rumen fluid was measured in the presence and absence of viable bacteria. When no viable bacteria were present 74% of the saponins in the alfalfa appeared in rumen fluid after 8 h of incubation and this amount was unchanged at 24 h. Rate of release did not follow first order kinetics, rather an amount equivalent to approximately 8% of the original saponin concentration accumulated in the fluid each hour over the 8-h period. After 4 h, saponin concentrations in rumen fluid were decreased in the presence of viable bacteria indicating microbial metabolism was occurring. Final accumulation of saponins in the rumen fluid after 24 h incubation was 62% of that originally present in alfalfa samples when viable bacteria were present. It was concluded that saponins were rapidly released into rumen fluid and extensively degraded in the digestive tract. The implications of these observations on ruminant bloat are discussed.Key words: Alfalfa, saponins, digestibility, bloat, rumen fluid, bacteria Mathison, G. W., Soofi-Siawash, R., Klita, P. T., Okine, E. K. et Sedgwick, G. 1999. Dégradabilité des saponines de la luzerne dans l'appareil digestif du mouton et leur taux d'accumulation dans le liquide ruminal. Can. J. Anim. Sci. 79: 315-319. Deux expériences ont été réalisées pour suivre le sort des saponines de la luzerne dans le système digestif du mouton. Dans la 1 re , les animaux recevaient quotidiennement 14,4 ou 28,8 g de saponines par voie intraruminale, correspondant, dans l'ordre, à 62 et à 78 % de l'apport total de saponines dans le rumen. Les taux de dégradabilité des saponines dans le tractus digestif étaient, respectivement, de 96,0 et 97,9 % (P = 0,13), mais on n'a pas cherché à déterminer le degré de parenté des produits de dégradation avec les molécules d'origine. Dans la 2 e expérience, nous mesurions le taux de relargage des saponines de la luzerne dans le liquide ruminal en présence et en l'absence de bactéries actives. En l'absence des bactéries, 74 % des saponines de la luzerne apparaissaient dans le liquide au bout de 8 h d'incubation, la poursuite de l'incubation jusqu'à 24 h n'apportant aucun changement ultérieur de la proportion. La courbe de relargage ne suivait pas une cinétique du premier ordre, mais on observait plutôt l'accumulation dans le liquide de l'équivalent d'approximativement 8 % de la concentratio...