Effect of barley variety and dietary barley content on digestive function in beef steers fed grass hay-based diets

. 2000. Canola screenings as a fiber source in barley-based feedlot diets: effects on rumen fermentation and performance of steers. Can. J. Anim. Sci. 80: [161][162][163][164][165][166][167][168]. Two experiments were conducted to determine the feeding value of canola screenings in combination with barley grain for beef steers. Four dietary treatments were used. These included canola screenings:barley grain ratios of 100:0; 75:25, 50:50, and 25:75 (as-fed basis). In a metabolic trial, the effects of dietary treatment on ruminal fermentation parameters were determined in a 4 × 4 Latin square design experiment using four ruminally fistulated steers. In a production trial, 66 individually fed steers were used in an 83-d finishing trial to determine the performance and carcass characteristics of feedlot cattle fed different levels of canola screenings. A barley grain/barley silage-based control diet was also fed for comparison purposes. Ruminal pH decreased (P < 0.05) while total volatile fatty acid concentrations increased (P < 0.05) as the level of barley grain in the diet increased. Ruminal NH 3 -N followed a pattern (P < 0.05) similar to that of pH. Inclusion level of canola screenings had no effect on DM intake. However, ADG and feed efficiency increased (P < 0.05) as the level of barley grain in the diet increased. Increasing the level of barley grain in the finishing diet decreased (P < 0.05) lean meat yield and increased (P < 0.05) carcass fat. It was concluded that canola screenings can be included as a source of fiber in barley-based diets. However, levels in excess of 500 g kg -1 reduced the performance of feedlot steers. Performance and cost of gain with 250 and 500 g kg -1 canola screenings in barley-based finishing diets were comparable with those fed an 800 g kg -1 barley grain and 200 g kg -1 barley silage diet. Formulation of finishing diets for beef cattle to attain desired levels of productivity can involve numerous feed ingredients. Some factors influencing choice of dietary ingredients include cost, availability, animal acceptability and desired level of performance. Current finishing rations for western Canadian beef cattle are formulated with limited roughage levels (50 to 150 g kg -1 DM basis). The use of low roughage diets allows for the formulation of energydense diets and improves the ability to mix and deliver large quantities of feed. In finishing diets, roughages are primari-

Section: Metabolism Trialsupporting

confidence: 93%

Canola screenings as a fiber source in barley-based feedlot diets: effects on rumen fermentation and performance of steers

Pylot¹,

McKinnon²,

McAllister³

et al. 2000

“…The duodenal flow measurements, however, did not support this hypothesis, as ruminal OM and NDF digestibilities were not statistically different between the two diets. The observed higher ruminal ammonia concentration in the heifers fed the barley diet was a result of increased N intake with this diet and greater ruminal degradability of soybean meal compared to corn gluten meal (Reynal and Broiderick 2003) and of barley grain vs. corn grain CP (Reynolds et al 1993;Feng et al 1995). The increased concentrations of total VFA and acetate with the barley diet indicate a more intensive microbial fermentation compared with the corn-based diet, and agrees with existing literature (Martin-Orue et al 2000b;Khorasani et al 2001;Hristov et al 2002).…”

Section: Discussionsupporting

confidence: 79%

“…Composition of the diets may have also influenced MN flow. Compared to corn, barley increased MCP production in some studies (Feng et al 1995), but not in others (Casper et al 1999). Excretion of allantoin and uric acid in the urine did not indicate a significant effect of grain type on MCP measured using the urinary PD method.…”

Section: Discussionmentioning

confidence: 92%

Comparison of purines and nitrogen-15 as microbial flow markers in beef heifers fed barley- or corn-based diets

Hristov¹,

McAllister²,

Ouellet³

et al. 2005

. 2005. Comparison of purines and nitrogen-15 as microbial flow markers in beef heifers fed barley-or corn-based diets. Can. J. Anim. Sci. 85: 211-222. The objective of this study was to estimate the contribution of microbial purine bases to duodenal purines and to purine derivatives [allantoin and uric acid (PD)] excreted in the urine. Additionally, microbial protein (MCP) flow estimated using duodenal flow of purine bases was compared to estimates using 15 N as a microbial marker. Four beef heifers were fed two diets, barley silage/barley grain/soybean meal (diet B) or corn silage/corn grain/corn gluten meal (diet C), in a cross-over design study. ( 15 NH 4 ) 2 SO 4 was infused in the rumen for 8 d to label ruminal microorganisms and their purine bases. Rumen contents, duodenal digesta, urine, and feces were sampled during the last 2 d of tracer infusion and for 48 h after the infusion ceased. The animals consumed more (P < 0.01) dry matter (DM), organic matter (OM), N, and neutral detergent fiber (NDF) with diet B than with diet C. Total tract digestibilities of DM, OM, and NDF were also higher (P < 0.01) with diet B. Ruminal ammonia (P < 0.01), volatile fatty acids (P < 0.05), and acetate (P < 0.01) concentrations and xylanase activity (P < 0.05) were higher with diet B compared with diet C. Flow of MCP to the duodenum was estimated from duodenal samples using purines or 15 N as microbial markers, or from urinary PD excretion. The effects of diet or method of measurement on MCP flow were not significant. However, when the urinary PD method was excluded from the analysis, MCP flow was greater (by 26%; P = 0.01) when estimated using 15 N vs. the purine-based method. The difference was mainly due to underestimation of the proportion of microbial N in the liquid duodenal digesta with the purine method. Feed purines contributed from 3.5 (liquid digesta phase) to 19.7% (solid digesta phase) of the total purine flow at the duodenum. 15 Nenrichment of urinary PD was 1.08 of the enrichment of duodenal purines, suggesting that feed purines contributed little N to urinary allantoin and uric acid in cattle. a été infusé dans le rumen pendant huit jours afin de marquer les microorganismes du rumen et leurs bases puriques. Les auteurs ont prélevé des échantillons du contenu du rumen, des digests du duodénum, de l'urine et des fèces au cours des deux derniers jours de l'infusion et 48 heures après celle-ci. Les animaux ont consommé plus (P < 0,01) de matière sèche (MS), de matière organique (MO), d'azote (N) et de fibres au détergent neutre (FDN) avec la ration B qu'avec la ration C. La digestibilité de la MS, de la MO, du N et des FDN dans l'ensemble du système digestif était aussi plus élevée (P < 0,01) avec la ration B. La concentration d'ammoniaque (P < 0,01), d'acides gras volatils (P < 0,05) et d'acétate (P < 0,01) dans le rumen ainsi que l'activité de la xylanase (P < 0,05) dans le fluide du rumen étaient plus élevées avec la ration B qu'avec la ration C. On a estimé le MCP dans le duodénum à partir d'échantillons d...

“…One hundred grams of grass hay chopped to 19 mm and labeled with Yb were mixed with digesta contents and put back into the rumen via the cannula. The hay was labeled with Yb by soaking it in 100 mL of a solution containing 3.89 g of Yb(NO 3 ) 3 .5H 2 O and allowing the hay to dry overnight at room temperature (Feng et al 1998).…”

Section: Passage Ratesmentioning

confidence: 99%

Effects of barley silage particle size and concentrate level on rumen kinetic parameters and fermentation patterns in steers

Soita

Christensen²,

McKinnon³

2003

. 2003. Effects of barley silage particle size and concentrate level on rumen kinetic parameters and fermentation patterns in steers. Can. J. Anim. Sci. 83: 533-539. Four Hereford steers (471 ± 31 kg) fitted with ruminal cannulae were used in a 4 × 4 Latin square design to evaluate the effects and possible interactions between silage particle size and concentrate level on digestion and ruminal fermentation parameters. Diets were designed with two forage to concentrate ratios [low forage, 20:80, high forage, 50:50 on a dry matter (DM) basis], combined with two theoretical chop lengths of barley silage; short (SBS) = 4.7 mm and long (LBS) =18.8 mm. Results showed that steers fed diets with SBS consumed more DM than those fed LBS. An interaction (P < 0.05) between particle size and concentrate level was noted for molar proportion of acetate. At the higher concentrate level, feeding SBS diets reduced the molar proportion of acetate but increased the molar proportion of propionate. An interaction (P < 0.05) between particle size and concentrate level was noted for ruminal pH. When compared to LBS, the daily mean rumen pH was lower (P < 0.05) for steers fed SBS with 80 % concentrate but not for those fed the 50% concentrate diet. Ruminal ammonia concentration was higher (P < 0.05) for those steers fed the 50% concentrate diets than for those fed the 80% concentrate diets. With high concentrate levels, SBS greatly reduced (P < 0.05) ammonia concentration. Passage rates for particulate matter and the retention time were decreased (P < 0.05) when SBS was fed. Feeding SBS reduced (P < 0.05) total tract digestibility of dry matter, crude protein (CP) and neutral detergent fiber (NDF) (65.5 vs. 68.5%, 66.5 vs. 73.4% and 39.4 vs. 45.9%), respectively. These results suggest that barley silage with a theoretical cut length of 18.8 mm can promote higher rumen pH, ammonia nitrogen, and reduced particulate passage rates. These changes in rumen fermentation parameters should favor optimum rumen function and digestion when high concentrate diets are fed. . Les résultats indiquent que les bouvillons nourris d'une ration SBS consomment plus de matière sèche. Les auteurs ont remarqué une interaction (P < 0,05) entre la taille des particules et la quantité de concentré au niveau de la proportion molaire d'acé-tate. Quand il y a plus de concentré, les petites particules diminuent la proportion molaire d'acétate et augmentent celle de propionate. Ils ont aussi noté une interaction (P < 0,05) entre la taille des particules et la quantité de concentré pour le pH dans le rumen. Ainsi, les petites particules d'ensilage réduisent la moyenne quotidienne du pH dans le rumen (P < 0,05) des bouvillons nourris avec la ration renfermant 80 % de concentré, mais pas dans celui des bouvillons recevant la ration à 50 % de concentré. Le rumen des animaux à qui on avait servi la ration renfermant 50 % de concentré contenait plus d'ammoniac (P <0,05) que celui des bouvillons recevant 80 % de concentré. Quand la ration renferme beaucoup de concentré, des p...