A 2 × 2 factorial experiment was conducted to investigate the interaction between high and low dietary crude protein (CP) (200 v. 150 g/kg) and sugar-beet pulp (SBP) (200 v. 0 g/kg) on nutrient digestibility, nitrogen (N) excretion, intestinal fermentation and manure ammonia and odour emissions from 24 boars (n = 6, 74.0 kg live weight). The diets were formulated to contain similar concentrations of digestible energy (13.6 MJ/kg) and lysine (10.0 g/kg). Pigs offered SBP-containing diets had a reduced (P < 0.05) digestibility of dry matter, ash, N, gross energy and an increased (P < 0.001) digestibility of neutral-detergent fibre compared with pigs offered diets containing no SBP. There was an interaction between CP and SBP on urinary N excretion and the urine : faeces N ratio. Pigs offered the 200 g/kg CP SBP-based diet had reduced urine : faeces N ratio (P < 0.05) and urinary N excretion (P < 0.05) compared with those offered the 200 g/kg CP diet without SBP. However, there was no effect of SBP in pigs offered 150 g/kg CP diets. Manure ammonia emissions were reduced by 33% from 0 to 240 h (P < 0.01); however, odour emissions were increased by 41% (P < 0.05) when pigs were offered SBP diets. Decreasing dietary CP to 150 g/kg reduced total N excretion (P < 0.001) and ammonia emissions from 0 to 240 h (P < 0.05). There was an interaction between dietary CP and SBP on branched-chain fatty acids (P < 0.001) in caecal digesta. Pigs offered the 200 g/kg CP SBP-containing diet reduced branched-chain fatty acids in the caecum compared with pigs offered the 200 g/kg CP diet containing no SBP. However, there was no effect of SBP in the 150 g/kg CP diet. In conclusion, pigs offered SBP-containing diets had a reduced manure ammonia emissions and increased odour emissions compared with diets containing no SBP. Pigs offered the 200 g/kg CP SBP-containing diet had a reduced urine : faeces N ratio and urinary N excretion compared with those offered the 200 g/kg CP diet containing no SBP.

Feeding behaviour of six sows receiving a diet with a high inclusion (500 g/kg) of sugar-beet pulp (SBP) was compared with that of six sows receiving a conventional cereal-based diet (control). The feeding rate was determined for both the rate of consumption of the daily food allowance (SBP or control diet) and of a test portion (of control diet) offered at different intervals after the daily food allowance. SBP sows consumed their daily food allowance more slowly than control sows, SBP sows also consumed the test portion more slowly than control sows, when this was offered immediately after the daily food allowance. Prolonging the time taken to eat the control diet, by presenting it in meal form, did not change the feeding rate of the test diet. Offering the test portion 2 h after the daily food allowance, increased the feeding rate of the test portion for both control and SBP sows, with a smaller but still significant treatment difference. Gastric distension appeared to be a major factor in regulating intake when feeding a diet containing SBP. The extent to which feeding rate could be used as an index of feeding motivation and the welfare consequences of using bulky diets for sows are discussed.

Forty days after mating, 16 pregnant sows were randomly allocated to two diets containing either sugar-beet pulp (SBP) or wheat straw (WS) each offered at two levels (1·0 or 1·5 × maintenance energy requirement (M), where M = 460 kJ digestible energy (DE) per kg0·75 per day). Diets were iso-nitrogenous, and contained similar levels of DE together with 260 g non-starch polysaccharides (NSP) per kg dry matter (DM) largely derived from either the SBP or the WS. A 7-day NSP and DM balance was made between day 60 and 100 of gestation. During lactation sows had ad libitum access to a conventional sow diet which contained neither SBP or WS.

Outputs of both fresh and dry faeces from sows given diet WS were significantly greater than the outputs from sows given the corresponding SBP diets (P <0·05), and outputs were significantly greater at the higher feeding level for both diets (P < 0·05). There was a tendency for higher urinary outputs from sows given diet WS, but these were variable and not significantly different from those from sows given diet SBP. The apparent digestibility and retention of DM was significantly greater for the SBP diet than for diet WS but were not significantly affected by feeding level. The apparent digestibilities of the total NSP and each of the individual constituent monomers were significantly higher for diet SBP than for diet WS (P < 0·001), but were independent of feeding level (P> 0·05). Xylose was the most poorly digested NSP constituent from both diets. Apparent digestibility coefficients for the remaining NSP constituents in diet SBP were > 0·8 and were > 0·52 in diet WS, with the uronic acids and mannose being the most highly digested NSP fractions from diets SBP and WS respectively.

Twenty-eight Suffolk-cross male castrated lambs aged 7 to 8 months, initial live weight 36 (s.e. 149) kg were given four diets which contained unground pelleted molassed sugar-beet pulp and rolled barley (940 g/kg, fresh weight basis) in the following proportions either A, 0·8 to 0·2 or B, 0·5 to 0·5, with 60 g soya-bean meal per kg. Diets A and B were offered with or without a yeast culture product Yea-Sacc. Diets zvere offered twice daily to appetite with 100 g hay per head. Yeast culture had no effect on any measurement made (P > 0·05). Lambs given diet B consumed more dry matter (DM), grew faster and had superior food conversion efficiencies (all P < 0·01). Rumen fluid taken 3 h after feeding contained higher concentrations of ammonia (F < 0·01), total volatile fatty acids (F < 0·001) and acetic acid (F < 0·001) in samples from lambs given diet A. Rumen fluid samples collected before the 10·00 h meal, produced more gas from diet A than diet B after 6 and 24 h in vitro incubation (F < 0·001) suggesting the presence of more undigested food. When ground diets were incubated, more gas was produced from diet A after 6h (F < 0·05) but not after 24 h fP > 0·05). It is suggested that diet B supported faster growth of the lambs as a result of faster rate of digestion, higher DM intake and superior food conversion.

Twelve Large White × Landrace boars, initial mean live weight (kg) 5·51 (s.e. 0·8) were offered cereal-based diets containing 0 (diet C) or 150 g sugar-beet pulp per kg (containing no molasses or other additive) (diet 15SB) and the indigestible marker titanium dioxide from 21 to 57 days of age. The daily intakes, live-weight gains and food conversion ratios of the piglets were monitored from day 28. The apparent digestibilities of nitrogen (N), gross energy (GE) and non-starch polysaccharides (NSP) were measured on days 32 and 56. There were no significant differences either in voluntary intakes, or in the daily live-weight gains and food conversion ratios between the two diets. Likewise, there were no significant differences in the apparent digestibility of N and GE of the two diets. However, the capacity at 56 days of age to digest N from diet 15SB was greater than at 32 days of age. The apparent digestibility of total NSP at both 32 and 56 days of age was significantly greater for diet 15SB (averaging 0·75) than for diet C (averaging 0·54) (P < 0·001). The major NSP components of diet 15SB were arabinose, glucose and uronic acids, but the predominant NSP constituents of diet C were arabinose, xylose and glucose. The apparent digestibilities of arabinose (P < 0·05), mannose (P < 0·05), glucose (P < 0·05) and uronic acids (P < 0·001) were significantly greater from diet 15SB than from diet C. The apparent digestibility of NSP components from both diets tended to increase with age of piglet. These results are discussed in relation to the early establishment of an efficient gut microflora and indicate that the fermentative capacity of very young pigs may be higher than previously thought.

Experiments involving both digestion and growth trials were undertaken to compare the responses of pigs to two increments of digested energy resulting either from gut fermentation or from digestion by endogenous enzymes in the small intestine. Unmolassed sugar-beet pulp (SBP) and maize starch (MS) were selected as model materials for these two systems. A control diet was formulated to fulfil the needs of pigs for all essential nutrients apart from energy. This diet was offered according to a scale set at about twice the maintenance energy requirement. The two SBP diets contained 150 and 300 g SBP per kg (SBP15 and SBP30) and the two MS diets 100 and 200 g MS per kg (MS10 and MS20). Sixty observations were made with 10 female and 20 male growing pigs to provide information on digestion. The results showed that the energy in SBP and MS had an apparent digestibility of 0·74 and 0·98 respectively (s.e.d. 0025). The neutral-detergent fibre fraction of SBP had a digestibility of 0·81 (s.e. 0·055). Forty pigs (20 male and 20 female) were involved in the growth trial. The responses of pigs to increments of different digestible energy (DE) were measured in terms of daily carcass-weight gain. The results gave values of 435, 478, 527, 511 and 567 (s.e.d. 17·3) g/day for the control, SBP15, SBP30, MS 10 and MS20 treatments respectively. These results suggest that the apparent DE of SBP is used for carcass growth with an efficiency of 0·57 (s.e. 0·012) relative to the DE from MS.