Changing the grazing session from morning to afternoon or including tannins in the diet was effective in decreasing the urinary nitrogen of dairy cows fed a total mixed ration and herbage

Our aim was to evaluate whether increasing soluble carbohydrates in the herbage by changing the time of the grazing session or including Acacia mearnsii tannin in the diet would affect intake, digestion, N partitioning, and productive performance of dairy cows fed a diet combining ryegrass herbage with partial total mixed ration (PMR). We hypothesized that both strategies could reduce the concentration of NH3-N in the rumen, reducing urinary N excretion. Nine Holstein cows were used in a triplicate 3 × 3 Latin square experiment with 3 experimental periods of 22 d. The cows were fed a fixed amount of PMR [60% of the predicted individual dry matter intake (DMI)], and an unrestricted amount of herbage in 1 grazing session of 5 h/d. The treatments were (1) morning grazing session and afternoon PMR meal (AM); (2) morning PMR meal and afternoon grazing session (PM); and (3) morning grazing session and afternoon PMR meal supplemented with 15.0 g of tannins/kg of PMR dry matter (TAN). Milk production was not affected by treatments. Although the protein concentration was lower for TAN than for PM, no differences were detected for the yield of any component between treatments. The concentration of individual or grouped fatty acids in milk fat was not affected by treatments, except for 16:1 cis-9 and Δ9-desaturase ratios 14:1/14:0 and 16:1/16:0, which were lower for TAN. Treatments did not affect total DMI, but PM tended to increase herbage DMI and reduce dry matter and crude protein digestibilities. Treatments did not affect cow eating and ruminating behavior except for the proportion of time spent eating PMR, which was higher for PM and TAN. Although no relevant effects of treatments on ruminal fermentation, purine derivatives excretion in urine, or N excretion in milk were detected, both PM and TAN decreased the total N excreted in urine by an average of 8% compared with AM. In conclusion, changing the grazing session from the morning to the afternoon and including tannins in the diet were effective in decreasing the excretion of urinary N but did not change the productive performance of dairy cows fed PMR and ryegrass herbage.Fil: Pozo, Claudio. Universidade Federal de Santa Maria; BrasilFil: Kozloski, Gilberto V.. Universidade Federal de Santa Maria; BrasilFil: Cuffia, Maira. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Repetto, José L.. Universidad de la República; UruguayFil: Cajarville, Cecilia. Universidad de la República; Urugua

The Role of Bacteria and Fungi on Forage Degradation \u3ci\u3ein Vitro\u3c/i\u3e

The study was conducted to evaluate the interactive role of bacteria and fungi on forage degradation in vitro. Samples of Cynodon spp. were incubated in a 48-h in vitro gas assay with incubation medium containing or not antimicrobial substances. Treatments were: antibiotic (Ab), antifungal (Af), negative control (i.e. without antimicrobials) or positive control (i.e. with both Ab and Af). Three replicate assays were conducted and, in each assay the gas volume was measured at 3, 6, 9, 12, 24, 36 and 48 h of incubation. Data of cumulative gas production in each flask in each assay was fitted to a one-pool logistic model which generated three kinetic parameters: total gas production, rate of gas production and lag time. For statistical analysis, data of triplicates in each run were averaged and each run was considered a replicate. All variables were significantly affected by treatments (P \u3c 0.05). Compared to negative control treatment, Ab decreased total gas production and the rate of gas production by 26 and 13 %, respectively, and increased the lag time by 5.5 hours. The inclusion of Af also decreased total gas production and the rate of gas production by 5 and 29%, respectively, whereas decreased the lag time by 1 hour. When both Ab and Af were included in the incubation medium, gas production was almost completely inhibited and no convergent data of fermentation parameters was generated. In conclusion, bacteria had a major role on forage degradation what, however, was increased by fungi activity. The mechanisms by which fungi interact with bacteria for degrading forage into the rumen needs to be elucidated

Evaluation of Internal Markers for Estimating Duodenal Digesta Flow in Ruminants: Acid Detergent Fibre and Lignin Disappearance at the Lower Gastrointestinal Tract

Most of published studies carried out for estimating organic matter (OM) rumen digestibility (OMRD) use research an-imals fitted with simple t-type cannulas and an external or internal marker for estimating the duodenal digesta flow. Compared to external, the internal markers have the advan-tage of occurring naturally in diet and, consequently, they flow intimately associated with digesta (Titgemeyer 1997). Porter and Singleton (1971a) reported from a study with sheep fitted with re-entrant duodenal cannula that lignin degradation takes place entirely in the stomach. Thus, in digestibility studies where total faeces output is measured, duodenal digesta flow may be estimated based on both faeces output and the ratio of lignin concentration in faeces and in duodenal digesta. However, sulphuric acid lignin (ADL) is present in low concentrations in duodenal digesta and the precision of duodenal flow estimates is usually compromised. This study evaluated the disappearance at the lower gastrointestinal tract and, consequently, the po-tential use of acid detergent fibre (ADF), in comparison with ADL, as an internal marker for estimating duodenal digesta flow in cattle

Evaluation of Acid Detergent Fibre, Sulphuric Acid Lignin and N-Alkanes as Markers for Estimating Ruminal Digestibility in Cattle

Most of the published studies on estimating organic matter (OM) rumen digestibility (OMRD) use research animals fitted with simple t-type cannulas and an external or inter-nal marker for estimating the duodenal digesta flow. Although there is not an ideal or standard marker, com-pared to external markers, internal markers have the advantage of occurring naturally in the diet and, conse-quently, they flow intimately associated with digesta (Titgemeyer 1997). In digestibility studies where total faec-es output is measured, duodenal digesta flow may be estimated based on both faeces output and the ratio of a marker concentration in faeces and in duodenal digesta. Sulphuric acid lignin (ADL) has been commonly used as an internal marker in this approach. However, its low concen-trations in duodenal digesta usually compromises estimate precision. The objective of this study was to evaluate acid detergent fibre (ADF) in comparison with ADL, as well as with n-alkanes, as a marker for estimating OMRD in cattle

Predicting Forage Intake by Sheep through the Pampa Corte Model or NRC

The aim of the present study was to evaluate the precision and accuracy of the Pampa Corte and National Research Council (2007; NRC) models for predicting forage intake (FI) by sheep. Individual data (n = 213) of observed FI, body weight and chemical composition of consumed diet were taken from fifteen indoor digestibility trials conducted with male sheep housed in metabolic cages and fed only forage ad libitum. The diets were composed of tropical grasses, temperate grasses and legumes. Individual observations of FI were averaged by treatment (n = 32) into each experiment which were then compared to FI values predicted by Pampa Corte model or NRC using concordance correlation coefficient (CCC) and regression analysis. The average value of observed FI was 847 (± 241) whereas those predicted by Pampa Corte model and NRC were, respectively, 826 (± 230) and 987 (± 208) g DM/day. Observed values of FI were linearly related (P \u3c 0.01) to those predicted through either Pampa Corte or NRC. However, the Pampa Corte resulted in higher CCC than NRC. Also, through the Pampa Corte model, the linear regression presented a slope not different from 1 and an intercept not different from 0. The NRC model, however, resulted in a slope of the linear regression lower than 1 despite the intercept was not different from 0. The Pampa Corte model was more precise and accurate in predicting FI by sheep fed only forage than NRC

Production Per Animal and Use of Intake Estimatives to Predicted Animal Productivity in \u3cem\u3ePennisetum Purpureum\u3c/em\u3e cv. Mott and \u3cem\u3eCynodon\u3c/em\u3e spp cv. Tifton 85 Pastures

Dairy production is a very important activity in southern Brazil, being an essential source of income to small household farms. Milk production from pastures is an alternative to reduce costs in dairy systems. Some C4 grasses, such as dwarf elephant grass (DEG) and Tifton 85, have presented high animal production per animal and per area. Although studies evaluating milk production from these pastures are rare in south Brazil, in vitro studies have demonstrated that the nutritional value of these forages is higher than production registered in grazing. So, it is possible that, in spite of a high intrinsic nutritional value, limitation on cows’ productivity is linked to the food’s capacity of conversion to milk and/or management conditions that limit forage intake. Leaf mass in pastures is a factor that determinates forage intake, as cows prefer leaf to other parts of plants. In this context, adequate animal performance may be possible if offered enough leaf biomass at pasture. The aim of this experiment was to evaluate the potential of milk production with these two forage species

Calculating herbage utilization and intake by dairy cows under subtropical conditions using conventional field measurement techniques or the HerbValo method

This study aimed to evaluate the HerbValo method in comparison to conventional field measurement techniques as a tool for estimating the herbage utilization and dry matter (DM) intake by grazing dairy cows under subtropical conditions. It was carried out during 18 months in a commercial farm of Southern Brazil. The herbage utilization was estimated monthly in two to four randomly selected paddocks (total n = 40) using the rising-plate meter or the double-sampling technique. In parallel, the herbage utilization was estimated by the HerbValo method, which is based on simple descriptions of the herd, supplements, pasture and grazing management. Values of herbage utilization estimated by field techniques were linearly (P < 0.01) related to those estimated by HerbValo, with no effect of pasture type (tropical vs. temperate) on the origin or on the slope of the regression (slope = 0.97; origin = -0.1; R 2 = 0.81; rsd = 0.17 t DM/ha). At cow × day level, values of herbage intake estimated by field techniques were also linearly related to those estimated by HerbValo (P < 0.01; R 2 = 0.82; rsd = 1.30 kg DM/cow/day). A negative linear relationship (P < 0.01) between herbage and supplement intake was obtained for both field (slope = -1.06; R 2 = 0.72; rsd = 1.64) and HerbValo (slope = -0.92; R 2 = 0.82; rsd = 1.08) approaches. Herbage utilization and intake by a dairy herd in a subtropical grazing-based system can be reliably estimated by the HerbValo method with the advantage of not requiring direct field pasture measurements.Fil: Wlodarski, Letícia. Universidade Federal de Santa Maria; BrasilFil: Delagarde, Rémy. Institut National de la Recherche Agronomique; FranciaFil: Pozo, Claudio Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Formosa. Provincia de Formosa. Centro de Investigaciones y Transferencia de Formosa. Universidad Nacional de Formosa. Centro de Investigaciones y Transferencia de Formosa; ArgentinaFil: Ribeiro Filho, Henrique M. N.. Universidade Federal de Santa Catarina; BrasilFil: Temp, Larissa B.. Universidade Federal de Santa Maria; BrasilFil: Moraes, Matheus L.. Universidade Federal de Santa Maria; BrasilFil: Santos, Mateus G.. Universidade Federal de Santa Maria; BrasilFil: Kozloski, Gilberto V.. Universidade Federal de Santa Maria; Brasi

Inclusion of exogenous enzymes in feedlot cattle diets: Impacts on physiology, rumen fermentation, digestibility and fatty acid profile in rumen and meat

The objective of this study was to evaluate if the inclusion of a blend composed of exogenous enzymes (amylase, protease, cellulase, xylanase and beta glucanase) in the individual and combined form in the feedlot steers diet has benefits on the physiology, rumen fermentation, digestibility and fatty acid profile in rumen and meat. The experiment used 24 animals, divided into 4 treatments, described as: T1-CON, T2-BLEND (0.5 g mixture of enzyme), T3-AMIL (0.5 g alpha-amylase), T4-BLEND+AMIL (0.5 g enzyme blend+ 0.5 g amylase). The concentration of mineral matter was higher in the meat of cattle of T4-BLEND+AMIL. A higher proportion of monounsaturated fatty acids was observed in the T3-AMIL group when compared to the others. The percentage of polyunsaturated fatty acids was higher in the T2-BLEND and T4-BLEND+AMIL compared to the T1-CON. The combination of exogenous enzymes in the diet positively modulate nutritional biomarkers, in addition to benefits in the lipid and oxidative profile meat