SUM M ARYTen Polwarth × Texel lambs (26 ± 2·1 kg live weight (LW)), housed in metabolism cages and offered ryegrass (Lolium multiflorum) ad libitum, were used in a 5 × 5 Latin Square experiment to evaluate the effect of supplement type on digestion processes and on amino acid and energy supplies. Five of the 10 lambs were fitted with a rumen catheter and duodenal cannulae. Treatments included no supplement (control); 7 g/kg LW daily of cassava meal (Manihot esculenta, high-starch low-nitrogen (HS-LN)), cassava meal plus corn gluten meal (2:1, high-starch high-undegradable N (HS-UN)), cassava meal plus calcium caseinate (2·8:1, high-starch high-degradable N (HS-DN)) or corn gluten feed (low-starch high-degradable N (LS-DN)). Total intake of dry matter (DM), organic matter (OM) and N, as well as digestible OM intake were increased with HS-UN, HS-DN and LS-DN (P 4 0·050). Forage DM intake was reduced by HS-LN (P = 0·030). Apparent digestibility of DM and OM was increased by HS-LN and HS-DN (P 4 0·038). Digestibility of neutral detergent fibre (NDF) and OM true digestibility were similar for all treatments. Supplementation with HS-LN decreased duodenal flux of total N, amino acid N, ammonia N and feed residual N (P 4 0·023). None of the supplements affected rumen microbial protein entering the small intestine, whereas the efficiency of rumen microbial protein synthesis (EMPS) was reduced by HS-LN and HS-DN (P 4 0·036). Ruminal degradability of dietary N (RDN) was increased by HS-LN, HS-DN and LS-DN (P 4 0·050). In conclusion, supplementing lambs fed ryegrass with degradable or undegradable high-protein concentrate increased the amino acid supply without affecting the supply of digestible energy, regardless of either the starch content or the degree of ruminal degradability of the protein source. These results indicate that supplementation of ryegrass-based diets should include both starch and protein sources.

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The use of brown rice grain as corn grain replacer in dairy cow diets was investigated. The following treatments were evaluated: zero, 33, 63, and 100%. The experimental diets were iso in protein, energy and fiber levels. Eight multiparus Jersey cows were used. A replicated Latin square experimental design was applied. The inclusion of brown rice had no effect (P > 0.05) on dry mater intake and their constituents, apparent digestibility, production and milk composition, feed efficiency and blood chemistry profile. Therefore, the brown rice grain can be used replacing corn grains alternative feedstuff in dairy cow diets.

SUMMARYA set of independent assays were conducted to assess the effects of either pH or glucose concentration on forage degradation, bacterial adherence and on fibrolytic enzyme activityin vitro. For measuring degradation and bacterial adherence, ryegrass (Lolium multiflorum) and bermudagrass (Cynodon dactylon) samples were incubatedin vitrofor 24 h in the medium at different pH (5·5, 6·0, 6·5 or 7·0) or with different initial glucose concentrations (0, 1000, 2000 and 3000 mg/l). For fibrolytic enzyme activity evaluation, forage samples were incubatedin situand the extracted enzymes were incubatedin vitrounder the different pH and glucose treatment conditions. The amount of bacteria adhering to samples and the degradability of dry matter (DM) and neutral detergent fibre (NDF) were higher for ryegrass than for bermudagrass, were not affected by glucose concentration and were linearly and positively affected by increased pH. On average, carboxymethylcellulase (CMCase) and xylanase activities were higher for ryegrass than for bermudagrass in the pH assay, whereas the differences between forages were not significant in the glucose assay. For both forage species, the quadratic effect of pH or glucose concentration on CMCase and xylanase activities was significant. Maximum activity of both enzymes was observed at pH 6·0 or at glucose concentration of 2000 mg/l. In conclusion, forage degradation was affected negatively by decreased ruminal pH due to reduced bacterial adherence. In turn, the pH or glucose effect on fibrolytic enzyme activity was not related to their effects on bacterial adherence or forage degradation, indicating that forage degradation is more dependent on the degree of microbial colonization than on the specific activity of bacterial enzymes.

The aim was to evaluate how the fodder pre-dehydration time and its phenological stages influence on ruminal degradability and digestibility of ryegrass silage. The evaluated samples consisted of treatments: Vegetative: Cut and ensiled; cut + 4 hours pre-drying and ensiled and; cut + 7 hours pre-drying and ensiled; Pre-flowering: Silage cutting and ensiled and 4 hours pre-drying and ensiled; Flowering: cut and ensiled, no pre-drying, with four replications each treatment. Silage was storage for four months. It was carried out three in situ digestibility assays to determine the curve of ruminal degradability at different times (3, 6, 9, 12, 24, 48 and 72 hours), like in situ digestibility and other three assays of 24 hours and 48 hours to determinate in vitro digestibility of silage. The digestibility of ryegrass silage was influenced by both the pre-dehydration times and phenological stage, and the dehydration time of cut and silage had a high proportion of degradable components, with higher degradation rate by 24 hours of incubation. The in vitro digestibility of the ryegrass silage was greater than that in situ for up to 48 hours. The digestibility of the ensiled ryegrass biomass was influenced by the dehydration times, as well as the plant growth stage, regardless of the methodology used, being higher values for the treatment without previous drying of the vegetative stage.

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Inclusion of forage legumes in diet may improve tropical ruminant systems productivity and sustainability. However, it is not well stablished which chemical components more impact their nutritional value. The relationship between chemical composition and in vitro fermentation of tropical forage legume was evaluated with the objective of obtaining indicators of their nutritional value. Samples of Crotalaria spectabilis, Cajanus cajan, Macrotyloma axillare, Mucuna aterrina, Stylosantis sp. and Canavalia ensiformis, cut from plants at growth age between 47 to 110 days, were analysed. Total gas production showed negative correlation (P<0.05) with total N (R=-0.51), acid detergent fibre (ADF, R=-0.62) and acid detergent lignin (ADL, R=-0.65), and positive correlation with non-fibre carbohydrates (NFC, R=0.70). Gas production rate was negatively related (P<0.05) to NDF (R=-0.73), ADF (R=-0.62) and ADL (R=-0.74). Ammonia concentration in the incubation medium was positively related (P<0.05) to total (R=0.74) and soluble (R=0.56) N, and negatively related to NFC (R=-0.81). The level of bacterial adhesion on residue of incubation was negatively related (P<0.05) to cell wall components, mainly to ADL (R=-0.57). The inclusion of polyehtylene glycol increased both gas volume and gas production rate whereas decreased ammonia concentration (P<0.05). In conclusion, even at low concentrations tannins impact the in vitro fermentation of tropical legumes. However, among the analyzed chemical components, the ADL was the best indicator of the nutritional value of the tropical forage legumes.Index terms: Gas production, lignin, nutritional value, phenolic compounds, tannins. RESUMOA inclusão de leguminosas na dieta tem o potencial de melhorar a produtividade e sustentabilidade dos sistemas de produção de ruminantes em regiões tropicais. Contudo, não está bem estabelecido quais componentes químicos são os mais determinantes do seu valor nutricional. Este estudo avaliou a relação entre componentes químicos e a digestão in vitro de leguminosas forrageiras tropicais, com o objetivo de obter indicadores de seu potencial nutricional. Foram incluídas amostras de Crotalaria spectabilis, Cajanus cajan, Macrotyloma axillare, Mucuna aterrina, Stylosantis sp. e Canavalia ensiformis cortadas de plantas com idades de crescimento entre 47 a 110 dias. O volume de gases apresentou correlação negativa (P<0,05) com os teores de N (R=-0,51), fibra em detergente ácido (FDA, R=-0.62) e lignina em detergente ácido (LDA, R=-0,65), e positiva com o teor de carboidratos não fibrosos (CNF, R=0,70) das leguminosas. A taxa de produção de gases foi negativamente relacionada (P<0.05) com os teores de FDN (R=-0.73), FDA (R=-0.62) e LDA (R=-0.74). A concentração de amônia no meio foi positivamente correlacionada (P<0.05) com o teor de N total (R=0.74) e N solúvel (R=0.56) e, negativamente, correlacionada com o teor de CNF (R=-0.81). O grau de aderência bacteriana no resíduo de incubação foi negativamente relacionada (P<0.05) com os componentes da parede cel...

SUMMARY The present study aiming to determine the nutritional quality of oat (Avena sativa L.) IPR 126 in order to produce forage for ruminants. Four periods between harvests were used: 14, 21, 28 and 35 days, distributed in randomized blocks with four replicates for each treatment. The variables evaluated were: the concentration of dry matter (DM), neutral detergent insoluble fiber (NDF), crude potein (CP), lignin, dry matter (DM), ash, ether extract (EE) and in vitro digestibility of dry matter obtained by measurement of gas production. The profile of gas production was adjusted to the logistic bicompartimental mathematical model. The variables and the parameters of the adjusted gas production curves were analyzed as repeated measurements through the PROC MIXED of SAS (version 9.0) and the restricted maximum likelihood (REML) as the method of estimation of parameters. Regression analysis was performed for the variables: DM, CP, EE, NDF, ash, and for the parameter k2 of the bicompartimental model. DM and NDF concentrations increased linearly, CP, ash, and the estimations of the parameter k2 reduced linearly and the EE concentration showed a cubic behavior in function of the age of harvest. Lignin and other parameters of the Schofield model were not influenced by the age of harvest. The harvest interval influenced some chemical components and degradation rate of fiber carbohydrates, but do not interfere in lignin concentration. The forage with 21 days of cutting interval has the high nutritional value.