The aim of this experiment was to determine the chemical composition of six commonly utilized fodder trees and shrub species in Turkey, namely Glycrrhiza glabra L, Arbutus andrachne, Carpinus betilus, Juniperus communis, Quercus libari L and Pistica lentiscus and its relationship with gas production and estimated parameters when incubated with rumen fluid in vitro. There were significant (p<0.001) differences between leaves in terms of crude protein (CP), acid detergent fiber (ADF), total condensed tannin (TCT), bound condensed tannin (BCT) and soluble condensed tannin (SCT). Crude protein contents ranged from 5.74% (Juniperus communis) to 12.59% (Glycrrhiza glabra L). Acid detergent fiber contents ranged from 25.14% (Glycrrhiza glabra L) to 39.23% (Juniperus communis). Total condensed tannin (TCT) contents of leaves ranged from 4.34% (Quercus libari L) to 20.34% (Juniperus communis). Acid detergent fiber (ADF) and total condensed tannin contents of leaves were negatively correlated with gas productions and some estimated parameters. Potential gas productions (A) of Glycrrhiza glabra L, Arbutus andrachne, Quercus libari L and Pistica lentiscus were significantly (p<0.001) higher than those of Carpinus betilus and Juniperus communis whereas gas production rate (µ 24 ) of Pistica lentiscus was significantly (p<0.001) higher than the others. Time (h) to produce 50% of total gas pool size (T 50 ) of Juniperus communis was significantly (p<0.001) lower than that of Carpinus betilus whereas time (h) to produce 90% of total gas pool size (T 90 ) of Juniperus communis was significantly lower than the others except for Pistica lentiscus. The metabolizable energy (ME) contents of leaves ranged from 8.86 to 10.39 MJ kg -1 DM. The results obtained in this study suggested that browse species had a significant effect on chemical composition, gas production and estimated parameters of leaves. Leaves from Glycrrhiza glabra L with a considerable amount of CP had a high rank value in terms of ME. Therefore leaves from Glycrrhiza glabra L may have a high potential value for small ruminant animals in terms of rumen and whole digestibility. Leaves from other species studied require protein supplementation when they are the only feed consumed by ruminant animals.

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The aim of this study was to evaluate the chemical composition, in vitro DM degradability, ME and OMD of alfalfamaize silage mixtures in comparison to pure maize and alfalfa silages, and to test the existence of associative effects of ensiling alfalfa forage with whole-crop maize using the in vitro gas production technique. Ensiling alfalfa with whole-crop maize had a significant (p<0.001) effect on chemical composition, pH, in vitro DM degradability, OMD and estimated ME values of mixtures. DM content of the resultant silages significantly increased with increasing proportion of whole-crop maize in the mixtures, whereas the pH value, crude protein (CP), acid detergent fibre (ADF) and ash contents of mixtures decreased due to the dilution effect of whole-crop maize which was low in CP, ADF and ash. The pH values of all alfalfa-maize silage mixtures were at the desired level for quality silage. Gas production of alfalfa-maize silage mixtures at all incubation times except 12 h increased with increasing proportion of whole-crop maize. When alfalfa was mixed with whole-crop maize in the ratio 40:60, ME and OMD values were significantly (p<0.001) higher than other silages. Maximum gas production (A gas ) ranged from 65.7 to 78.1 with alfalfa silage showing the lowest maximum gas production. The results obtained in this study clearly showed that maximum gas production increased with increased percentage of whole-crop maize in the silage mixtures (r = 0.940, p<0.001). It was concluded that ensiling alfalfa with whole-crop maize improved the pH, OMD and ME values. However, trials with animals are required to see how these differences in silage mixtures affect animal performance.

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Dry matter (DM) degradation of wheat straw (WS), barley straw (BS), lucerne hay (LH) and maize silage (MS) was determined using two different techniques: (i) in vitro gas production and (ii) nylon bag degradability technique. In vitro gas production and in situ DM disappearance were measured after 3, 6, 12, 24, 48, 72 and 96 hours of incubation. In situ and in vitro DM degradation kinetics was described using the equation y = a + b (1 -e ct ). In all incubations there were significant (P < 0.001) correlations between gas production and in situ DM disappearance or estimated parameters ((a + b) gas and (a + b) is or (a + b) gas and EDMD is ) whereas there were no significant (P > 0.05) correlations between c gas and c is or b gas and b is . Gas production from the insoluble fraction (b) alone explained 98.3% of the variation of EDMD. The inclusion of gas production from the quickly soluble fraction (a) and rate constant (c) of gas production in the regression equation improved the accuracy of EDMD prediction. The correlations between the results of both methodologies seem to be sufficiently strong to predict degradability parameters from gas production parameters. It was concluded that the in vitro gas production technique has good potentiality to predict in situ DM disappearance and some DM degradation parameters.Keywords: in vitro gas production; in situ dry matter degradability; forage 61Czech J. Anim. Sci., 50, 2005 (2): 60-67 Original Paper et al., 1999Cone et al., 1999Cone et al., , 1998Cone et al., , 2002. However, the information available can be considered limited and results somewhat inconsistent. The aim of this study was (I) to determine fermentation kinetics using in vitro gas production and the in situ nylon bag technique and (II) to evaluate the correlations between the fermentation kinetics obtained by two different techniques. MATERIAL AND METHODS Forages and chemical analysisCommercially available and widely used four forages consisting of wheat straw, barley straw, lucerne hay and maize silage were used in this experiment. After drying forage samples were milled through a 1-mm sieve for chemical analysis. DM was determined by drying the samples at 105°C overnight and ashing the samples in a muffle furnace at 525°C for 8 h. Nitrogen (N) content was measured by the Kjeldahl method (AOAC, 1990). Crude protein was calculated as N × 6.25. Neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents were determined by the method of AOAC (1990). Starch content was determined by the method according to MacRea and Armstrong (1968). In vitro gas productionForage samples milled through a 1-mm sieve were incubated in vitro in rumen fluid in calibrated glass syringes following the procedures of Menke and Steingass (1988). Rumen fluid was obtained from three fistulated sheep fed twice daily with a diet containing lucerne hay (60%) and concentrate (40%). Digestion medium was prepared mixing 500 ml of distilled water, 0.1 ml micro-mineral solution, 200 ml buffer solution, 200 ml macro-mi...