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Diet composition can be estimated in free–ranging animals by the use of n–alkane and longchain fatty alcohol concentrations in feces. However, this technique involves relatively laborious and costly analytical techniques. Two spectroscopy techniques were investigated as a way of determining whether dietary differences are likely, thus indicating whether the more expensive and labor–intensive techniques for more detailed analysis are justified. Fourier–transform infrared spectroscopy (FTIR) and front–face fluorescence emission spectroscopy (χexcitation = 380 nm, χemission = 600 to 760 nm) were used to analyze fecal samples collected from 2 different breeds of cattle and sheep (4 groups in total, n = 6 per group) grazing moorland plants in 2 grazing sessions. These fecal samples were also analyzed for alkane and alcohol concentrations. Fourier–transform infrared spectra, particularly in the alkane regions, demonstrated clear separation between animal species. Fluorescence emission spectra showed similar separation; fluorophores were most likely chlorophylls and their derivatives. Multivariate analysis of all 3 data sets showed similar variation within and between groups of cattle and sheep, indicating differences in diet selection particularly between species, but also between breed and grazing session. Both spectroscopy methods showed utility in suggesting differences in diet composition that would be worth investigating using more detailed chemical analyses, Of the 2 techniques, the FTIR spectroscopy gave the better comparative results, being able to detect differences in sampling months that were detected with alkanes and alcohols that the fluorescence emission spectroscopy did not detect. [ABSTRACT FROM AUTHOR]

The experiment investigated the digestion of lipids from different forage silages in beef steers. Six Hereford × Friesian steers prepared with rumen and duodenal cannulas were given ad libitum access to a high-sugar grass silage, control grass silage, red clover silage, or mixtures of the red clover and each of the grass silages (50:50, DM basis). The experiment was conducted as an incomplete 5 × 5 Latin square, with an additional randomly repeated sequence. Total fatty acid and C18:3n-3 concentrations were greater (P < 0.05) for the high-sugar grass silage than the control grass silage or the red clover silage. Dry matter and total fatty acid intake were less (P < 0.05) for steers fed the control grass silage than for steers fed the other diets. Duodenal flow of C18:3n-3 was greater (P < 0.05), and flows of C 18:0 and total C 18:1 trans were less (P < 0.05), for the red clover silage compared with the 2 grass silage diets, with the mixtures intermediate. These results were supported by a reduction (P < 0.05) in biohydrogenation of C18:3n-3 for the red clover silage, with the mixtures again being intermediate. Flows of total branched- and odd-chain fatty acids were greater (P < 0.05) for the high-sugar grass silage diet, possibly as a result of greater microbial flow, because these fatty acids are associated with bacterial lipid. Duodenal flows of the chlorophyll metabolite, phytanic acid, were greater (P < 0.05) for animals fed the high-sugar grass silage treatments compared with the other treatments. These results confirm the potential for modifying the fatty acid composition of ruminant products by feeding red clover silage. [ABSTRACT FROM AUTHOR]

Two experiments were carried out to determine the effects of feeding grass silages differing in their water-soluble carbohydrate content, with or without red clover silage, on the efficiency of nutrient use. High-sugar grass, control grass, and red clover were ensiled in laboratory silos for use in an in vitro experiment (Exp. 1). For an in vivo experiment (Exp. 2), the same forage types were baled and ensiled. All silages were well preserved; within experiments the grass silages had similar composition, except for greater (P < 0.05) water-soluble carbohydrate concentrations in the high-sugar than the control grass silage. In Exp. 1, high-sugar grass, control grass, and red clover silages were fed alone or as mixtures (30:70, 50:50, or 70:30 on a DM basis, respectively) of each grass with the red clover silage to a simulated rumen culture system. There were no significant differences in microbial N flow or efficiency of microbial protein synthesis between individual forages. However, the corresponding values for the 70:30 ratio of high-sugar grass:red clover silage were greater (P < 0.05) than for the red clover silage. The value for the efficiency of N use (g of microbial N/g of feed N) was greater (0.86; P < 0.05) for high-sugar grass silage than the control grass silage. In addition, the high-sugar grass:red clover silage mixtures all gave greater (P < 0.05) values for the efficiency of N use than red clover silage alone; this difference was not achieved with the control grass mixture. Experiment 2 was an incomplete Latin square design conducted with 6 Hereford × Friesian steers (163 ± 5.9 kg of BW) with rumen and duodenal cannulas fed the following 5 silage diets: high-sugar grass silage; control grass silage; high-sugar grass and red clover silage (50:50 DM basis); control grass and red clover silage (50:50 DM basis); and red clover silage. Rumen NH3-N concentration was lowest (P < 0.05) with the high-sugar grass silage. Microbial N flows to the duodenum and efficiency of microbial protein synthesis were greater (P < 0.05) for steers fed the high-sugar grass silage than for control grass and red clover silages, and mixing red clover with grass silages increased (P < 0.05) these values compared with red clover silage alone. In both experiments, the efficiency of incorporation of silage N into microbial N was more than 20% greater (P < 0.05) for high-sugar grass than for control grass silage. These data suggest that grass silage with high-sugar content provides a forage-based strategy for balancing N and energy supply and improving the efficiency of use of grass silage N in the rumen. [ABSTRACT FROM AUTHOR]

The experiment investigated the digestion of lipids from different forage silages in beef steers. Six Hereford × Friesian steers prepared with rumen and duodenal cannulas were given ad libitum access to a high-sugar grass silage, control grass silage, red clover silage, or mixtures of the red clover and each of the grass silages (50:50, DM basis). The experiment was conducted as an incomplete 5 × 5 Latin square, with an additional randomly repeated sequence. Total fatty acid and C18:3n-3 concentrations were greater (P < 0.05) for the high-sugar grass silage than the control grass silage or the red clover silage. Dry matter and total fatty acid intake were less (P < 0.05) for steers fed the control grass silage than for steers fed the other diets. Duodenal flow of C18:3n-3 was greater (P < 0.05), and flows of C 18:0 and total C 18:1 trans were less (P < 0.05), for the red clover silage compared with the 2 grass silage diets, with the mixtures intermediate. These results were supported by a reduction (P < 0.05) in biohydrogenation of C18:3n-3 for the red clover silage, with the mixtures again being intermediate. Flows of total branched- and odd-chain fatty acids were greater (P < 0.05) for the high-sugar grass silage diet, possibly as a result of greater microbial flow, because these fatty acids are associated with bacterial lipid. Duodenal flows of the chlorophyll metabolite, phytanic acid, were greater (P < 0.05) for animals fed the high-sugar grass silage treatments compared with the other treatments. These results confirm the potential for modifying the fatty acid composition of ruminant products by feeding red clover silage. [ABSTRACT FROM AUTHOR]

Two experiments were carried out to determine the effects of feeding grass silages differing in their water-soluble carbohydrate content, with or without red clover silage, on the efficiency of nutrient use. High-sugar grass, control grass, and red clover were ensiled in laboratory silos for use in an in vitro experiment (Exp. 1). For an in vivo experiment (Exp. 2), the same forage types were baled and ensiled. All silages were well preserved; within experiments the grass silages had similar composition, except for greater (P < 0.05) water-soluble carbohydrate concentrations in the high-sugar than the control grass silage. In Exp. 1, high-sugar grass, control grass, and red clover silages were fed alone or as mixtures (30:70, 50:50, or 70:30 on a DM basis, respectively) of each grass with the red clover silage to a simulated rumen culture system. There were no significant differences in microbial N flow or efficiency of microbial protein synthesis between individual forages. However, the corresponding values for the 70:30 ratio of high-sugar grass:red clover silage were greater (P < 0.05) than for the red clover silage. The value for the efficiency of N use (g of microbial N/g of feed N) was greater (0.86; P < 0.05) for high-sugar grass silage than the control grass silage. In addition, the high-sugar grass:red clover silage mixtures all gave greater (P < 0.05) values for the efficiency of N use than red clover silage alone; this difference was not achieved with the control grass mixture. Experiment 2 was an incomplete Latin square design conducted with 6 Hereford × Friesian steers (163 ± 5.9 kg of BW) with rumen and duodenal cannulas fed the following 5 silage diets: high-sugar grass silage; control grass silage; high-sugar grass and red clover silage (50:50 DM basis); control grass and red clover silage (50:50 DM basis); and red clover silage. Rumen NH3-N concentration was lowest (P < 0.05) with the high-sugar grass silage. Microbial N flows to the duodenum and efficiency of microbial protein synthesis were greater (P < 0.05) for steers fed the high-sugar grass silage than for control grass and red clover silages, and mixing red clover with grass silages increased (P < 0.05) these values compared with red clover silage alone. In both experiments, the efficiency of incorporation of silage N into microbial N was more than 20% greater (P < 0.05) for high-sugar grass than for control grass silage. These data suggest that grass silage with high-sugar content provides a forage-based strategy for balancing N and energy supply and improving the efficiency of use of grass silage N in the rumen. [ABSTRACT FROM AUTHOR]

Red clover and fish oil have been shown to alter ruminal lipid metabolism increasing PUFA and conjugated linoleic acid (CLA), respectively, in ruminant products. This study investigated the additive effect of these two feeds on C18 PUFA metabolism in beef steers. Eight Hereford × Friesian steers prepared with rumen and duodenal cannulae were offered either grass or red clover silage at 90% ad libitum with one of three levels of fish oil 0, 1, 2, or 3 % DMI. The experimental design consisted of four 2 × 2 Latin squares within each oil level with an extra period. Flows of fatty acids at the duodenum were assessed using the dual phase-indigestible-marker technique. DMI was significantly (P < 0.001) higher for red clover silage (5.98) than grass silage (5.09 kg/d). Oil level had no effect on DMI with the exception of red clover at 3% oil which was significantly (P < 0.01) lower. C18:2 n-6 and C18:3 n-3 intakes averaged 13.2 and 25.1 for grass silage and 17.9 and 36.2 g/d for red clover silage, respectively. Biohydrogenation of C18:2 n-6 and C18:3 n-3 were significantly lower (P < 0.001) on red clover silage than grass silage with oil level increasing the extent of biohydrogenation in both diets (P < 0.05; 0.81 and 0.85 to 0.91 and 0.92 for grass silage and 0.76 and 0.73 to 0.87 and 0.83 for red clover silage at 0 and 3 % oil, respectively). C18:1 trans was significantly increased by oil level for both diets (4.6 to 15.0 and 9.4 to 22.5 for grass and red clover silage at 0 and 3 % oil, respectively). Oil level increased the proportion of C18:1 trans 11 in the duodenal digesta in both diets from 0.47 and 0.31 with no oil to 0.52 and 0.51 at 3 % oil for grass silage and red clover silage, respectively. CLA was also significantly increased on both diets by oil level (0.21 and 0.27 to 0.48 and 0.57 g/d for grass and red clover silage at 0 and 3 % oil, respectively). The results of this study show that red clover and fish oil have the potential to beneficially alter the fatty acid profile of ruminant products. [ABSTRACT FROM AUTHOR]

Polyphenol oxidase (PPO) oxidizes endogenous phenols to quinones, which react with nucleophilic sites of other compounds such as proteins. In red clover (Trifolium pratense L.) , this complexing reaction has been shown to reduce both plant mediated proteolysis and lipolysis. This experiment investigated the role of red clover PPO on lipolysis in the presence and absence of rumen microorganisms. Triplicate macerated shoot samples of two red clover lines, a wild type with a basal level of PPO activity (High PPO) and a mutant with reduced PPO activity (Low PPO), were incubated in anaerobic buffer, with and without strained rumen liquor inoculum (I+ and I-), at 39°C, and sampled at six time (0, 1, 2, 4, 6 and 24 h). At each time point the samples were destructively harvested and lipolysis measured as percentage loss of membrane lipid. Lipolysis data was analysed using a general analysis of variance with repeated measurements (Genstat 8®). The table shows the reducing effect of PPO on lipolysis (High vs Low) but also the elevated level of lipolysis when micro-organisms are present (I+ vs I-). If the PPO effect was solely due to the deactivation of plant lipases this difference should be neutralized through the addition of microbial lipases. The retention of the PPO effect in the I+ treatments suggests that PPO exerts some form of protection on the membrane lipids in a manner similar to the complexing of protein. The lipid in forages is mainly in the form of polar membrane lipids, and polar lipid - phenol complexes could form due to the highly electrophilic nature of the PPO-produced quinones. [ABSTRACT FROM AUTHOR]

Diet composition can be estimated in free–ranging animals by the use of n–alkane and longchain fatty alcohol concentrations in feces. However, this technique involves relatively laborious and costly analytical techniques. Two spectroscopy techniques were investigated as a way of determining whether dietary differences are likely, thus indicating whether the more expensive and labor–intensive techniques for more detailed analysis are justified. Fourier–transform infrared spectroscopy (FTIR) and front–face fluorescence emission spectroscopy (χexcitation = 380 nm, χemission = 600 to 760 nm) were used to analyze fecal samples collected from 2 different breeds of cattle and sheep (4 groups in total, n = 6 per group) grazing moorland plants in 2 grazing sessions. These fecal samples were also analyzed for alkane and alcohol concentrations. Fourier–transform infrared spectra, particularly in the alkane regions, demonstrated clear separation between animal species. Fluorescence emission spectra showed similar separation; fluorophores were most likely chlorophylls and their derivatives. Multivariate analysis of all 3 data sets showed similar variation within and between groups of cattle and sheep, indicating differences in diet selection particularly between species, but also between breed and grazing session. Both spectroscopy methods showed utility in suggesting differences in diet composition that would be worth investigating using more detailed chemical analyses, Of the 2 techniques, the FTIR spectroscopy gave the better comparative results, being able to detect differences in sampling months that were detected with alkanes and alcohols that the fluorescence emission spectroscopy did not detect. [ABSTRACT FROM AUTHOR]