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Total tract digestibility and nitrogen retention of three diets containing different levels of fibre [200, 260 and 320 g/kg neutral detergent fibre (NDF) in dry matter] were determined in three breeds of growing pig at an initial age of approximately 3.5 months. The breeds were local (Mong Cai, MC), F1 crossbred (MC x Yorkshire) and exotic (Landrace x Yorkshire, LY), allocated at random within breed (block) to double 3 x 3 Latin squares. The main fibrous ingredients of the experimental diets were rice bran, cassava residue meal and non-dehulled groundnut cake meal. Digestibility of organic matter (OM), crude protein (CP), NDF, crude fibre, gross energy (GE) and ether extract (EE) decreased as the level of dietary NDF increased (p < 0.001). The r(2) values for the relationship between NDF level and digestibility of OM, CP, GE and EE were 83%, 83%, 80% and 82% respectively. On average, an increase in NDF content of 1% unit resulted in a decrease in OM, CP, GE and EE digestibility of 0.67%, 0.75%, 0.50% and 0.42% units respectively. Digestibility of energy and nutrients was the highest for MC and the lowest for LY (p < 0.01), with intermediate values for F1. There was a negative effect of NDF level on nitrogen (N) retained as a proportion of intake (p < 0.05). Nitrogen retention and utilization were significantly higher (p < 0.001) for LY than for MC and F1 pigs.

The objective of the present work was to assess the influence of partial replacement of oats with dried unmolassed sugar beet pulp (SBP) and/or maize oil on nutrient utilisation in horses fed a traditional hay and concentrate diet. The total tract digestibility of nutrients, urinary excretion and plasma parameters were studied in a 4 x 4 Latin-square design experiment with purebred Arabian geldings. Horses fed the SBP diets responded with a reduced (P<0.05) apparent digestibility of crude protein and feeding of maize oil resulted in an increased (P<0.05) apparent digestibility of crude fat. The apparent energy digestibility was unaffected by the replacement of oats with SBP, but increased (P<0.05) when maize oil replaced part of the oats. The urinary excretion of nitrogen increased (P<0.05) when maize oil replaced oats and the excretion of energy was higher (P<0.05) on the diets where oats were replaced by maize oil and SBP. There was a significant (P<0.05) effect across treatments of postprandial blood sampling time on plasma glucose and insulin concentrations. Also, plasma concentrations of glucose and insulin tended to be higher on the oats than on the SBP diets. In conclusion, the limited effects on the digestibility of nutrients and energy suggest that it should be possible to partially replace oats with maize oil and/or SBP in diets for horses without any impairing effects on the overall nutrient utilisation. However, the dietary-induced changes in the urinary excretion of energy and on plasma glucose and insulin levels, indicate a possible influence of dietary carbohydrate composition on nutrient utilisation at the organ level, which requires further study.

1. In Expt 1 three male goat kids of the Swedish Landrace breed were bottle-fed on isoenergetic liquid diets composed of goat's milk alone or substituted with 200, 400, 600 and 800 ml of a nitrogen-free liquid diet/l. The goat kids were 3 weeks old at the start of the experiment and weighed on average 5.3 (SD 0.22) kg. The experiment lasted for 45 d divided into nine 5 d periods. The goat kids were kept individually in metabolism cages, and faeces and urine were collected daily. 2. In Expt 1 there was a significant (P less than 0.001) relation between N intake and N retention, with an estimated (extrapolation) basal N excretion of 211 mg N/kg metabolic live weight (W0.75). While the creatinine excretion remained fairly constant (19.9 mg/W0.75), there was a tendency for both the allantoin and uric acid excretions to change with N intakes. Hypoxanthine showed no consistent excretion pattern, and xanthine could not be detected. 3. In Expt 2 three male goat kids of the Swedish Landrace breed were used to study the effect of level of intake on N and purine metabolism. The first experimental period (period 1) started at 2 weeks of age (5.5 kg live weight) and the second experimental period (period 2) at 9 weeks of age (9.8 kg live weight). The goat kids were bottle-fed on goat milk at intended intakes of 400, 600, 800 and 1000 kJ gross energy/kg W0.75. Each treatment was given for 7 d with adaptation for 3 d and collections for 4 d. 4. In Expt 2 there were significant (P less than 0.001) increases in both live weight and N retention when level of intake was increased. With increasing N intakes both total N and urea-N excretions increased significantly (P less than 0.05). The proportions of urea-N and ammonia-N were fairly constant within periods, and were on average respectively 0.81 and 0.059 in period 1 and 0.84 and 0.068 in period 2. There was no significant effect of treatment on the urinary excretion of allantoin, hypoxanthine, xanthine and creatinine. In period 2 uric acid excretion was significantly (P less than 0.01) affected by the treatments. 5. From the presented findings it is concluded that the endogenous urinary excretion of purine derivatives in a young growing ruminant was only marginally affected by large variations in protein supply, and also by the level of intake of milk.

Rapeseed (Brassica napus), barley grain, ryegrass (Lolium perenne) and barley straw were labelled with 15N as an internal marker. The dilution of 15N was used to estimate microbial N (RMN15N) in the feed residues in nylon bags incubated in the rumen for 5, 12 and 24 h. For comparative purposes, diaminopimelic acid (DAP) content of the residues was also determined and rumen microbial N (RMNDAP-N) in the feed residues calculated using DAP as a bacterial marker. The influence of two bag pore sizes (20 microns and 40 microns) with different sample sizes (1 g and 5 g respectively) was also studied. For all feeds, the average disappearance of 15N was faster than that of total N, the difference between N and 15N disappearance being marked with barley, ryegrass and barley straw. The disappearance of microbially corrected dry matter (DM; correction calculated from the 15N values) was, accordingly, always faster than the uncorrected DM disappearance. Except for the bag pore/sample size effect for N disappearance, significant (P less than 0.01-0.001) feed, pore/sample size and incubation-time effects were always found for the disappearance values. Errors (%) resulting from the microbial contamination (calculated from the 15N values) in N-loss measurement with rapeseed, barley, ryegrass and barley straw, at 5, 12 and 24 h in 20 microns bags were respectively: -1.8, -3.9, -0.9; -3.8, -22.4, -3.8; -7.2, -4.1, -2.9; -164.5, -146.3, -204.6. In 40 microns bags the corresponding errors were respectively: -4.4, -1.2, -0.7; -26.1, -10.5, -3.9; -13.2, -6.4, -5.5; -221.2, -310.1, -1284.6.(ABSTRACT TRUNCATED AT 250 WORDS)

The objective of this study was to investigate the effect of CP intake from 2 grass silage-only diets, differing in CP concentration, fed at similar DM1 on the equine colon ecosystem after an abrupt feed change between the diets. Four adult right ventral colon-fistulated geldings were fed one silage-only diet high in CP (HP, 873 g of CP/d) and one diet providing recommended intakes (RP, 615 g of CP/d). An adaptation period of 15 d on either the HP or the RP diet was followed by 2 experimental periods when the diets were fed for 22 d each in a crossover design. Colon samples were taken before and at 4, 12, and 24 h, and at 7, 14, and 22 d after the feed change. During the first 24 h after the abrupt feed change, the concentrations of total anaerobic bacteria and lactobacilli were greater on the HP than the RP diet (7.1 vs. 6.7 log[sub10] cfu/mL, P = 0.021, 6.0 vs. 5.5 log[sub10] cfu/mL, P= 0.021, respectively). During the first 24 h post feed change, VFA concentrations did not differ between the diets. From 7 to 22 d, total VFA concentrations were greater on the HP diet than on the RP diet (51.8 vs. 45.1 mmol/L, P = 0.034), and colon pH was lower on the HP diet than on the RP diet (6.9 vs. 7.2, P = 0.035). After an adaptation period of 22 d, N, ammonia, and urea concentrations and osmolality of the colon fluid did not differ between diets. Fecal pH and colon and fecal DM were unchanged throughout the experiment. The results suggest that, in horses fed at the maintenance level of energy intake, a feed change between silages with different CP content may alter the colon bacterial counts within the first 24 h. Moreover, during the subsequent 3 wk, pH decreased slightly and VFA concentrations increased, but no other major alterations occurred in the composition and activities of the colon ecosystem or fecal DM. [ABSTRACT FROM AUTHOR]

Digestibility and nitrogen (N) balance studies were carried out on the leaves of short-term (ST ) and long-term (LT ) varieties of cassava, preserved by sun-drying and grinding into a meal or by ensiling. The cassava leaf meal and ensiled leaves (471 and 373 g/kg total diet dry matter, respectively ) were mixed with palm syrup and palm oil, to give the experimental diets CLM and CLS, respectively. Four Mong Cai (MC) (17·2 (s.e. 2·61) kg) and four Landrace × Yorkshire ( L×Y ) (41·5 (s.e. 2·12) kg) male castrate pigs were used. The experiment was designed as a 2 × 2 × 2 factorial, with breed, cassava variety and processing method as factors. The hydrogen cyanide (HCN) levels of the fresh cassava leaves of ST (545 mg/kg dry matter (DM)) and LT (408 mg/kg DM) varieties were reduced by proportionately 0·63 and 0·33, respectively, after sun-drying and by 0·78 and 0·77, respectively, after ensiling. Intake was higher for DM, crude protein (CP) and organic matter (OM) ( P <0·001) and neutral- and aciddetergent fibre (NDF and ADF) and crude fibre (CF) (P detergent <0·01) in CLM than in CLS. There was a breed by processing method interaction for CF intake (P <0·05). The coefficient of total tract apparent digestibility (CTTAD) was higher in CLS than in CLM for DM, CP, OM and CF (P <0·001) and NDF and ADF (P <0·01). The MC pigs digested ADF (P <0·01) and CF (P<0·001) more effectively than L×Y pigs but there was no difference (P >0·05) in the digestibility of other nutrients or DM. There was a breed by cassava variety interaction for ADF digestibility and breed by processing method for CF digestibility (P <0·01). Daily N intake and faecal N were higher (P <0·001) in CLM than in CLS. Urinary N was lower in CLS than in CLM ( P <0·05) and in L×Y than in MC pigs ( P <0·001). N utilization (N retained per unit intake) was higher for CLS than CLM ( P <0·001) and in L×Y than in MC pigs ( P <0·001). It is concluded that ensiling is a more effective method than sun-drying for reducing HCN in cassava leaves after 60 days re-growth, and also results in higher digestibility of DM and dietary components than sun-drying. However, the bulkiness of the silage limits intake. The MC pigs digested dietary fibre more efficiently than the L×Y pigs, whereas the L×Y pigs utilized N more efficiently than the MC pigs. [ABSTRACT FROM AUTHOR]