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The effects of different water-soaking treatments on removal of water-soluble carbohydrates (WSC), WSC constituents and protein from four UK hays were determined. Hays were soaked in water for up to 16 hours at mean temperatures of 8°C, 16°C, in hot tap water (initially 49°C) or agitated and rinsed in clean water at 16°C. Initial hay WSC contents ranged from 154 to 216 g/kg dry matter. Losses of WSC from hays after 16 hours soaking at 8°C, 16°C, 16°C plus agitation and 49°C averaged 28, 46, 49 and 44 per cent, respectively. Corresponding percentage losses of fructan were 16, 37, 39 and 33. Percentage losses of sucrose averaged 55 (8°C), 86 (16°C), 91 (16°C+agitation) and 82 (initial temperature 49°C), those of glucose were 60, 85, 75 and 75, and of fructose were 41, 52, 54 and 46. Hay crude protein contents were not significantly changed by any of the soaking treatments. Soaking at 8°C generally resulted in reduced losses of WSC compared to when soaked at the higher temperatures. Thus, in cold weather using warmer water to soak hays may effect greater WSC loss, although very prolonged soaking at warm temperatures might encourage the proliferation of unwanted micro-organisms in the soak liquor.

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The aim of this study was to determine the amounts of water-soluble carbohydrate (WSC), WSC constituents and protein leached from a range of U.K. hays soaked according to common practice. Initial hay WSC content ranged from 123 to 230 g/kg dry matter (DM). Soaking the hays for up to 16 hours in water at a mean temperature of 8°C resulted in a mean loss of 27 per cent (range 6 to 54 per cent) of hay WSC. The mean percentage losses of WSC constituents were 24 per cent (range 14 to 31) for fructan, 41 per cent (range 21 to 70) for fructose, 45 per cent (range 28 to 100) for sucrose and 56 per cent (range 29 to 100) for glucose. The mean crude protein content of the initial hays was 58.7 g/kg DM (range 30 to 86 g/kg DM) and this value was not affected significantly by soaking. Despite a mean WSC loss of 27 per cent, the WSC contents of seven of the hays remained above the suggested upper limit for laminitic animals of 100 g/kg DM.

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Welsh-cross pony geldings (about 300 kg live weight) were used in a 4x4 Latin square experiment to determine the rate of passage and apparent digestibility of unchopped big-bale grass silage (BBL), chopped big-bale grass silage (BBS), unchopped grass hay (HL) and chopped grass hay (HS) offered at approximately 15 g/kg live weight per d. On day 1 of collection weeks, ponies were fed 85 g ytterbium chloride hexahydrate-marked feed 1.5 h after the morning meal. Total faecal collections commenced 8 h later and continued for 168 h. Apparent digestibilities of feed DM, organic matter (OM), crude protein (CP, Nx6.25), acid-detergent fibre (ADF) and neutral-detergent fibre (NDF) were also determined. Faecal excretion data were subjected to the models of Pond et al. (1988) and digesta mean retention time (MRT) calculated from these models and using the algebraic method of Thielmans et al. (1978). Silage had significantly (P<0.05) higher digestibilities of DM, OM, CP, ADF and NDF than hay; however, chop length had no effect. All the models of Pond et al. (1988) accurately described (R(2)>0.8) the pattern of faecal marker excretion. MRT of BBL (29.0 h)>BBS(27 h)>HS and HL (26 h). Compartmental analysis using the G3 model of Pond et al. (1988) showed BBL and HS diets had longer MRT in the time-dependent compartment, whereas BBS and HL had longer MRT in the time-independent compartment. Results from this experiment indicate that BBL and BBS are readily accepted and digested by ponies. While Yb is a successful external marker for determining total tract MRT and for modelling faecal excretion curves in horses, the results did not allow any definite conclusions to be drawn on digesta MRT within the different compartments of the equid gut.

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An in sacco mobile bag technique was used to determine the rate and extent of disappearance of unmolassed sugar-beet pulp, soyabean hulls, hay cubes and an oat hull-naked oats mixture (67:33, w/w) in the foregut and total digestive tract of ponies. Ponies were administered naso-gastrically polyester mesh bags containing 350 mg feed, in a Latin square design. Bags were collected at the ileo-caecal junction (small intestine bag, SIB) and in the faeces (faecal bag, FB) and their residues analysed for proximate constituents and NSP composition and content. DM disappearances from individual bags were fitted to degradation profiles (Ørskov & McDonald, 1979) and effective degradability values determined. Significant differences (P<0.05) in DM, organic matter and crude protein losses from SIB were noted between feeds with hay cubes and oat hulls-naked oats > sugar-beet pulp and soyabean hulls. Acid-detergent fibre, neutral-detergent fibre and NSP disappearances were small and varied little between feeds. In contrast, FB losses showed significant (P<0.05) differences for all constituents measured with sugar-beet pulp > soyabean hulls > hay cubes > oat hulls-naked oats. Crude protein losses from sugar-beet pulp and soyabean hulls in FB were significantly higher (P<0.05) than from SIB. FB degradation curves showed degradation to be affected by bag residence time with sugar-beet pulp > soyabean hulls and the effective degradability showed that significantly more (P<0.05) sugar-beet pulp was lost at 40.0 and 60.0 h than for the other three feeds. These results show that sugar-beet pulp and soyabean hulls are rapidly degraded by ponies and could be used as alternatives to hay in equid rations. However, the foregut availability of crude protein from sugar-beet pulp is poor, so a readily digestible source of crude protein should be offered to animals with high protein demands when diets are based on sugar-beet pulp.

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Pigs (25-45 kg) were fed on either cereal or semi-purified basal diets supplemented with either high or low levels of sugar-beet pulp or wood cellulose (Solka-floc). The apparent digestibility and retention of N and apparent digestibility and metabolizability of energy (GE) and the apparent digestibility of non-starch polysaccharides (NSP) and their constituent monomers were measured during weeks 2, 4 and 6 of the trial. N and GE were less well-digested, retained or metabolized from cereal basal diets than from the corresponding semi-purified diets during all three periods. NSP from sugar-beet pulp was highly digestible, unlike that from Solka-floc which was relatively poorly digested. These differences of NSP digestibility were seen more clearly when incorporated in semi-purified diets. There was no significant increase in the digestibility or retention of N, or digestibility or metabolizability of GE, or in the digestibility of sugar-beet pulp NSP with increasing time-period on the diets. In contrast, the digestibility of Solka-floc NSP tended to increase with the time-period. The digestibility of NSP from the semi-purified diet with the high level of Solka-floc inclusion was much lower than that for the low level of inclusion, indicating that microbial activity had been reduced. In conclusion, adaptation to the diets in terms of N and GE balance may be complete after 1 week, but 3-5 weeks may be necessary before stability of measurements of the digestibility of resistant NSP monomers can be obtained.

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The anaerobic fungus Neocallimastix sp. strain R1 was grown for up to 5 days on a medium containing autoclaved Italian ryegrass hay as the carbon source. Culture supernatants and digested cell walls were harvested at 12-h intervals. Supernatants were analyzed for the fermentation products formate and acetate, and residual cell walls were analyzed for dry-matter and neutral-sugar losses. Fungal growth was accompanied by the digestion of plant cell walls and the accumulation of fermentation products in culture media. Dry-matter losses were accounted for by removal of four major neutral sugars (arabinose, galactose, glucose, and xylose) from the plant cell walls. First-order reaction kinetics could be used to describe the loss of each sugar. All cell wall sugars, including arabinose and galactose, which are not fermented by Neocallimastix sp. strain R1 were removed simultaneously. Although the rates of removal of individual sugars were similar, there were significant differences in their extents of removal: the extent of removal of arabinose exceeded that of the other three sugars, and xylose was the least digestible. This study provides the first account of simultaneous (nonpreferential) removal of neutral sugars from plant cell walls by an anaerobic fungus. Although in vitro techniques were used, these results indicate a potentially significant role for the anaerobic fungi as fiber digesters in the rumen.