Relationship between digesta transit time and apparent metabolisable energy value of wheat in chickens

1.?This study tested the hypotheses that: (a) apparent metabolisable energy (AME) values and whole tract transit time (WTTT) were related, and that (b) the relationship between AME and WTTT differed between male and female Ross broiler chickens.

2.?Enzyme products with xylanase activity were added to a basal diet to provide 4 dietary treatments comprising control (no enzyme), Avizyme 1300 (1 kg/tonne), Kemzyme W1 (1 kg/tonne), and Bio-Feed Wheat CT (200 g/tonne). The basal diet comprised (in g/kg), 800 wheat, 155 casein, 20 dicalcium phosphate, 11 limestone, 7 D,L-methionine, 2 vitamin and mineral premix, 3 sodium chloride and 2 choline chloride (60%).

3.?AME values for diets were determined in a 7-d energy balance study commencing when chickens were 21 d of age. WTTT was the time elapsed (in min), from time of administration by oral gavage of 200 mg ferric oxide in a gelatine capsule, to time of first observation of the distinctive red colouration in droppings.

4.?The mean AME value for the wheat was high (15·7 MJ/kg dry matter) and ranged from 14·4 to 16·3 MJ/kg dry matter for individual birds. Mean WTTT was 206 min and ranged from 105 to 429 min. AME and WTTT were unaffected by enzyme addition to the diet, and the interaction between diet and gender was not significant.

5.?There was a significant but weak positive relationship between AME and whole tract transit time, with AME increasing by 2·2 kJ/min. This relationship was unaffected by gender of the chicken.     

Comparison of two direct bioassays using 3-week-old broilers to measure the metabolisable energy of diets containing cereals high in fibre: differences between true and apparent metabolisable energy values

1. Nitrogen-corrected apparent and true metabolisable energy contents (AMEN and TMEN) of 12 diets, containing different amounts of maize, wheat, barley and rye, barley with beta-glucanase and maize with 0.05 g/kg guar gum were measured using 3-week-old male broilers. 2. The AMEN method involved: 4 d of dietary adaptation, 24 h of starvation, 54 h of ad libitum feeding, 24 h of starvation and daily total droppings collection. TMEN was measured after a 48 h starvation period followed by 2 d of tube-feeding two doses of 15 g of the diets and quantitatively collecting all the droppings after 48 h of starvation. The endogenous energy losses (EELN) were measured after tube-feeding 8 chickens with 30 g of glucose, also over 2 d. 3. The results show that a significant interaction exists between the nature of the diets and the method used to measure metabolisable energy. Differences between TMEN and AMEN values ranged from 1.03 to 1.98 MJ/kg dry matter. These differences were positively correlated with the total pentosan contents of the diet (r = 0.94), the natural logarithm of the viscosities of the water extracts (r = 0.87), the sum of the contents of total pentosans and total beta-glucan (r = 0.85), the calculated total non-starch polysaccharide contents (r = 0.79), the neutral detergent fibre contents (r = 0.76) and the total beta-glucan contents (r = 0.70). Furthermore, a significant interaction was found between diets and the method used to derive lipid digestibility. The differences between apparent and true lipid digestibility ranged from 0.05 percentage points for the wheat diet to 0.20 percentage points for the rye diet. 4. From the results of this trial, it appears that TMEN overestimates the energy value of high fibre diets.     

Inclusion of low metabolisable energy wheat in broiler diets and the incidence of the fatty liver and kidney syndrome

Chickens were fed a diet containing wheat of low metabolisable energy (ME) content (11.3 MJ kg-1 dry matter [DM]) or a diet containing a wheat of high-ME content (14.5 MJ kg-1 DM). The diets, although of identical ingredient composition differed in energy to protein ratio. Chicks fed the diet containing the low-ME wheat and with the low ratio had more severe biotin deficiency lesions but a much reduced incidence of the fatty liver and kidney syndrome.     

Effects of wheat variety and specific weight on dietary apparent metabolisable energy concentration and performance of broiler chicks

1. This study used 4 wheat cultivars (Brigadier, Chaucer, Consort, Reaper) from three locations (Crossnacreevy, C; Downpatrick, D; Limavady, L), which had given rise to differences in wheat specific weight (SW), to examine the relationships between apparent metabolisable energy (AME) concentration, broiler performance and wheat SW. 2. The diets contained (g/kg): wheat 744, casein 142, blended vegetable fat 50, dicalcium phosphate 22, potassium bicarbonate 10.8, sodium bicarbonate 7.5, arginine 5, methionine 2, binder 8, trace minerals/vitamins 7.2, titanium dioxide 1.5. The diets were heat-treated (80 degrees C for 2 min) prior to pelleting (3 mm die). 3. SW ranged from 63 to 77 kg/hectolitre (hl), averaging 66, 69 and 76 kg/hl at D, C and L, respectively. In vitro viscosity of the wheat samples ranged from 5.2 to 17.5 cps and thousand grain weight (TGW) from 33.4 to 47.3 g. Mean TGW was similar at C and D (38.7, 37.0 g) but higher at L (43.1 g). In vitro viscosity was similar at C and L (11.2, 10.2 cps) but somewhat higher at D (14.4 cps). Crude protein (6.25 N) ranged from 116 to 147 g/kg and tended to be higher at D. Starch, which ranged from 612 to 656 g/kg, was least at D (617 g/kg) and greatest at L (641 g/kg). 4. Crude protein, crude fibre and total non-starch polysaccharide (NSP) were negatively correlated with SW, the R2 being respectively 0.38 (P<0.05), 0.16 (NS) and 0.45 (P<0.05). TGW and starch concentration were positively correlated with SW (R2=0.70, 0.44, respectively). There was a weak (NS) negative relationship (R2=0.19) between in vitro viscosity and SW. For both TGW and in vitro viscosity, correlations improved when variety was taken into account (R2=0.95, 0.92, respectively). 5. There were no significant effects of variety on dry matter (DM) intake or live weight gain (LWG). Gain: food was significantly higher (P<0.05) for Consort than for the other three varieties and the metabolisable energy ratio (ME:GE) just failed to attain significance (P=0.062). Calculated wheat AME (MJ/kg DM) was significantly (P<0.05) higher for Consort than for the other three wheats. There was a good correlation (R2=0.49) for the total data set between gain:food and ME:GE. In vivo viscosity varied from 13.6 to 28.6 cps for individual treatments and was significantly affected by variety (P<0001). 6. Although there were no significant differences in DM intake or LWG due to site the values for L (SW 76) were 6 and 5% lower, respectively, than for D (SW 66). Gain:food was lower (P<0.05) for C (SW 69) than for D. ME:GE, wheat AME and ME:gain were not significantly different between sites. 7. There was a weak (R2=0.18) positive relationship between ME:GE and SW corresponding to a 2.5% increase in energy value for a 10 kg/hl increase in SW and no relationship between gain:food and SW. When variety was taken into the regression the slope was similar but R2 increased to 0.82. 8. ME:GE and wheat AME concentration were negatively correlated with wheat in vitro viscosity (R2=0.64, 0.55, respectively). 9. It was concluded that in vitro viscosity appears to provide a better basis than SW for prediction of the nutritive value of wheats of unknown variety. If the variety is known then SW could be used to predict energy value. However, the effect of quite a large change in SW (10 kg/hl) was relatively small.     

Influence of substitution method and of food intake on bioassays to determine metabolisable energy with chickens

1. Several different methods of assaying the metabolisable energy (ME) of ground maize and a maize and glucose mixture were studied. Over a 24‐h period fasted cockerels lost more energy and nitrogen in their excreta than those fed 15 g maize and 15 g glucose monohydrate.

2. Discrepancies in ME values of maize were found between 1) Hill's method (substitution for glucose) and 2) Sibbald's method (the difference between energy ingested and excreted, corrected for endogenous losses by a comparison with fasted controls). These discrepancies were attributed to differences in endogenous energy losses between fed and fasted birds and interactions between the test substance and reference diet.

3. No significant differences could be detected when substitution for glucose was compared to substitution for the entire diet in three experiments.

4. Significant differences in the ME of maize because of the composition of the basal diet were found (semi‐purified: practical; 17·20:14·56 kJ/g; and 50 g/kg added fat: 100 g/kg added fat; 15·94:16·69 kJ/g).

5. Food intakes equal to 70, 60 or 30% of ad libitum did not affect the ME of maize when the substitution for glucose method was used.

6. It is concluded that basal diets for ME determinations should be carefully selected because of possible interactions between dietary components. When ME is determined by feeding small amounts of the test material, endogenous losses may be over‐estimated because the control birds are in a different physiological state (fasted).

     

Comparisons of the starch equivalent (SE) and metabolisable energy (ME) systems in feeding cattle

Rations were formulated for dairy cows and for growing and fattening cattle by the starch equivalent (SE) and the new metabolisable energy (ME) system, to show in quantitative terms the differences that are recognised between the two systems. For a low-yielding cow, rations formulated by both systems are very similar, but for a high-yielding cow the SE system greatly underestimates energy requirement: at a production of 40 kg (8.8 gal) milk daily an extra 2 kg (4.4 lb) of a barley-soyabean concentrate is needed daily to meet the energy requirement according to the ME system. For a particular rate of gain in young newly weaned animals and in older animals gaining weight at a moderate rate on a high roughage diet, the energy level recommended by the ME system is lower than that by the SE system. The difference corresponds in each case to about 0.5 kg of a barley-soyabean concentrate daily. For older animals gaining weight rapidly on a high concentrate diet the ME system requires slightly more energy for a given weight gain, than the SE system.     

Strategies to improve the nutritive value of rice bran in poultry diets. II. Changes in oil digestibility,metabolisable energy and attempts to increase the digestibility of the oil fraction in the diets of chickens and ducklings

1. In experiment 1, the effects of age on oil digestibility and apparent metabolisable energy (AME) were measured in chickens and ducklings between 3 and 28 d of age on a diet with 400 g rice bran/kg. In experiment 2, a biosurfactant and a food lipase were added to diets of chickens containing 200 and 400 g rice bran/kg. In experiment 3, chicken diets containing 0 or 400 g rice bran/kg were supplemented with a food lipase (2 concentrations) or a food enzyme or their combination. 2. In experiment 1, oil metabolisability and AME increased substantially as chickens aged. Oil metabolisability was much higher in ducklings, when comparisons were made with chickens of similar age. 3. In experiment 2, lipase or biosurfactant gave no improvement in bird performance. Growth rate and food conversion ratio were, respectively, 23% and 10% better on diets with 200 compared to 400 g rice bran/kg. 4. In experiment 3, there was a significant growth response to lipase plus the enzyme mixture on the diet with 200 g rice bran/kg. On the diet with 400 g rice bran/kg, growth improvement was seen with the enzyme mixture only. 5. In experiment 3, enzyme addition did not increase oil metabolisability or AME. At 4 to 8 d of age AME was higher on the diet without rice bran but oil metabolisability was the same as on the diet with rice bran. At 19 to 23 d of age AME was similar but oil metabolisability was higher on the diet with rice bran than without. Droppings' dry matter was higher on diets without than with rice bran (32.4 vs 27.1%). 6. The response to lipase and the combination of this and a food enzyme suggest that there may be benefit in examining this interaction further although they had no effect on oil metabolisability or on AME. It is concluded that a stable AME for rice bran cannot be provided for chickens until at least 21 d of age.     

Influence of high dose of phytase and an emulsifier on performance,apparent metabolisable energy and nitrogen retention in broilers fed on diets containing soy oil or tallow

1. The effects of high dose of microbial phytase and an emulsifier on the performance, apparent metabolisable energy (AME) and nitrogen (N) retention in broilers fed on diets containing different fat sources were examined in a 5-week trial. Two fat sources (soy oil and tallow), two inclusion levels of E. coli phytase (500 or 1000 phytase units (FTU)/kg diet) and two inclusion levels of lysolecithin emulsifier (0 or 3.5 g/kg of diet) were evaluated in a 2 × 2 × 2 factorial arrangement of treatments.

2. Throughout the 5-week trial, soy oil supplementation improved weight gain and feed per gain compared with tallow, but had no effect on feed intake.

3. The high dose of phytase increased the weight gain and feed intake and lowered the feed per gain during d 1–21, but had no effect on performance parameters over the whole trial period.

4. An effect of emulsifier was observed for feed intake during d 1–21 and over the whole trial period. Addition of emulsifier increased feed intake compared with diets without emulsifier.

5. During weeks 1, 2, 3 and 5, birds fed on soy oil–based diets had higher nitrogen-corrected AME (AME_N) compared with those fed on tallow-based diets. During weeks 2, 3 and 5, the effect of phytase was significant for AME_N, with the high dose increasing the AME_N. During week 2, AME_N was increased with emulsifier addition.

6. During weeks 1, 2, 3 and 5, birds fed on soy oil–based diets had higher fat retention compared with those fed on tallow-based diets. The high dose of phytase improved the retention of fat during week 5 and the addition of emulsifier resulted in higher fat retention during week 1.

7. During weeks 2, 3 and 5, an interaction between fat source × phytase × emulsifier was observed for N retention. In soy oil–based diets, emulsifier plus 1000 FTU/kg phytase increased N retention compared with other groups, while in tallow-based diets, emulsifier addition increased N retention in diets with 500 FTU/kg, but not in 1000 FTU/kg diet.

8. Overall, the present data suggest that the dietary fat source influenced performance, AME_N and fat retention in broiler chickens. There is opportunity to improve bird performance during d 1–21, AME_N and fat retention with higher doses of microbial phytase. Addition of the emulsifier increased the AME_N during week 2 and tract retention of fat during week 1, but this effect was not translated into improvements in performance.

     

Influence of method of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy, digestive tract measurements and gut morphology of broilers

1. The aim of the present study was to examine the influence of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy (AME), digesta viscosity, and digestive tract measurements of broilers fed on wheat-based diets. The influence of the method of whole wheat inclusion (pre- or post-pelleting) was also compared. A 3 x 2 factorial arrangement of treatments was used with three diet forms (648 g/kg ground wheat [GW], GW replaced by 200 g/kg of whole wheat before [WW1] or after cold-pelleting [WW2]) and two xylanase levels (0 and 1000 XU/kg diet). 2. Birds given diets containing whole wheat had improved weight gains, feed efficiency and AME compared to those fed on diets containing ground wheat. The relative gizzard weight of birds fed WW2 diets was higher than in those fed GW and WW1 diets. Pre-pelleting inclusion of whole wheat had no effect on relative gizzard weight. Post-pelleting inclusion of whole wheat resulted in greater improvements in feed efficiency and AME than the pre-pelleting treatment. 3. Xylanase supplementation significantly improved weight gain, feed efficiency and AME, irrespective of the wheat form used. Viscosity of the digesta in the duodenum, jejunum and ileum were reduced by xylanase addition. Xylanase supplementation reduced the relative weight of the pancreas. 4. Neither xylanase supplementation nor whole wheat inclusion influenced the relative weight and length of the small intestine. 5. Xylanase supplementation increased ileal villus height. A significant interaction between diet form and xylanase was observed for ileal crypt depth. Xylanase supplementation had no effect on crypt depth in birds fed on diets containing GW, but increased the crypt depth in WW2 diets. No significant effects of diet form and xylanase supplementation were observed for the thickness of the tunica muscularis layer of gizzard or villus height, crypt depth, goblet cell numbers or epithelial thickness in the ileum. 6. Improved performance observed with post-pelleting inclusion of whole wheat was associated with increased size of the gizzard and improved AME. The gizzard development hypothesis, however, will not explain the improvements observed with pre-pelleting inclusion of whole wheat, suggesting the involvement of other factors.     

Influence of age, chemical composition and rate of inclusion on the apparent metabolisable energy of fats fed to broiler chicks

1. Vegetable oil (VO) and tallow (T) were evaluated at rates of 25, 50, 75, 100 and 125g/kg in a basal diet with broiler chicks aged 1.5, 3.5, 5.5 and 7.5 weeks of age using a total collection period of 72 h. 2. Apparent metabolisable energy, corrected to zero nitrogen retention (AMEN, MJ/kg) and apparent fat availability (AFA, g/kg) of the experimental diets were employed to estimate the dietary energy values of fats, by linear and quadratic regression. 3. AME of fats, determined from AFA, had smaller standard errors than those determined from AMEN. 4. There was a marked increase in the AME of fats from 1.5 to 3.5 weeks of age; thereafter, the improvement was less pronounced. 5. Rate of improvement in fat AME with age was greater with T than VO.     

A note on the effect of temperature on true and apparent metabolisable energy values of a layer diet

The effect of ambient temperature on the true (TME) and apparent metabolisable energy (AME) values of a layer diet was examined using White Leghorn cockerels.

The TME value found at the cool temperature (5 to 15 °C) was significantly higher than those found at hot (25 to 35 °G) and control (22 °C) temperatures. AME values were not significantly affected.     

A comparison of average daily gain,apparent digestibilities,energy balance,rumen fermentation parameters,and serum metabolites between yaks(Bos grunniens) and Qaidam cattle(Bos taurus) consuming diets differing in energy level

Yaks (Bos grunniens),indigenous to the harsh Qinghai-Tibetan Plateau,are well adapted to the severe conditions,and graze natural pasture without supplements all year round.Qaidam cattle (Bos taurus),introduced to the Qinghai-Tibetan Plateau 1,700 years ago,are raised at a lower altitude than yaks,provided with shelter at night and offered supplements in winter.Based on their different backgrounds,we hypothesized that yaks have lower energy requirements for maintenance than cattle.To test this hy...     

Apparent metabolisable energy and amino acid digestibility of microalgae Spirulina platensis as an ingredient in broiler chicken diets

ABSTRACT

1. This work investigates the apparent metabolisable energy (AME), its nitrogen-corrected form (AMEn) and amino acid (AA) digestibility coefficients of the microalgae Spirulina platensis as an ingredient in broiler chicken diets.

2. One group of birds was fed with a basal control diet (BD), and another was fed with a test diet composed of the BD with the addition of the microalgae at a proportion of 200 g/kg. AME and AMEn were assessed by total excreta collection and indigestibility analysis using acid-insoluble ash (AIA) as a marker.

3. The microalgae comprised 888.0 g/kg dry matter (DM), 18.42 MJ/kg gross energy, 514.7 g/kg crude protein, 9.9 g/kg ether extract, 10.6 g/kg crude fibre, 94.4 g/kg ash, 3.1 g/kg Ca and 11.0 g/kg P.

4. The values obtained for AME (13.48 MJ/kg DM) and AMEn (11.72 MJ/kg DM) were higher (p < 0.01) than those obtained using the AIA method (9.39–8.29 MJ/kg DM). The microalgae ileal digestibility coefficients were 0.80 ± 0.04 and 0.78 ± 0.04 for essential and non-essential AA, respectively.

5. Overall, the metabolisable energy content and digestibility of AA for S. platensis indicated that the microalgae are potentially an alternative nutrient source for broilers. The AIA method underestimated AME and AMEn in comparison to the total excreta collection method.     

Hagberg falling number and the nutritional value of wheat in broiler chicken diets

1. Three experiments were performed to study the effect of Hagberg falling number in wheat on performance, nutrient digestibility and AMEN in broilers. In two experiments, one hard and one soft wheat variety were used to study the interaction between falling number and hardness of wheat with regard to nutritional value. In these experiments, wheat batches with high falling number when harvested under dry conditions were used in broiler diets. 2. Wheat with reduced falling numbers (high, medium and low) was obtained by controlled germination. In the third experiment, wheat with reduced falling numbers were obtained by delayed harvesting times. 3. In each experiment, a total of 4 cereal batches with different falling numbers from each wheat variety were used to produce corresponding experimental diets with wheat as the major ingredient. Each diet was fed to broiler chickens ad libitum from d 1 to d 17 of age. 4. There was no consistent effect of falling number on performance. Low falling number did not improve feed utilisation or AMEN compared to the original wheat, despite a higher AMEN associated with higher starch digestibility. This phenomenon was not observed after reduction of falling number by delayed harvesting. Apparently, natural reduction of falling number resulted in enhanced degradation of arabinoxylans compared to controlled germination.     

Effects of beta-glucanase-producing Lactobacillus strains on growth, dry matter and crude protein digestibilities and apparent metabolisable energy in broiler chickens

The effects of beta-glucanase expressed by transformed Lactobacillus strains on growth performance, apparent digestibilities of dry matter and crude protein, and apparent metabolisable energy were studied. Two hundred and forty 1-d-old chicks (Avian-43) were randomly divided into three dietary treatment groups and fed with the following diets: (i) basal diet (control) (BD); (ii) basal diet with parental Lactobacillus strains (BDP) and (iii) basal diet with transformed Lactobacillus strains (BDT). At 21 d of age, the body weight, body weight gain and feed conversion ratio of the BDT-fed chickens were significantly improved. At 14 and 21 d of age, the proportions of dry matter in the duodenum, jejunum, ileum, caeca and excreta of chickens given the BDT diet were significantly higher than those of chickens given the BD and BDP diets. Apparent metabolisable energy, digestibilities of crude protein and dry matter were also significantly improved (by 3.5, 5.6 and 3.5%, respectively) by the BDT diet. These results showed that the transformed Lactobacillus strains improved digestibility as well as enhanced the growth performance of chickens.     

Linear model of nitrogen balance and examination of the nature of true metabolisable energy and its nitrogen corrected form

1. The nature of nitrogen (N) corrected true metabolisable energy (TMEN) was derived using a linear model of N balance, constructed from the relationship between excreted and ingested N. 2. TME was described in terms of a regression line, formed from 'fed' points relating energy voided to energy ingested (GE), as GE- (afed + bGE)+afast. On assignment of theoretical excreta and ingested energy components, a deviation from conceptual metabolisable energy (MEc), equal to the difference between afed and afast, was established and attributed to metabolic urinary energy (UmE). 3. The N balance model is based on the form of relationship between N excreted and N ingested (Nl) that exhibits a linear deviation at 'initial' rates of N ingestion. The model postulates the following: The deviation is the result of a sparing effect of ingested N on the N component of UmE, viz. metabolic urinary N (UmN); The magnitude of UmN, through 'initial' values of fed N, is described by an intercept component, a a slope quantity, -(bnr-bna) Nl, where bNna and bnr are respectively the slopes of N excretion through 'initial' and 'subsequent' rates of ingested food N; The magnitude of the deviation from zero nitrogen balance (ZNB) through 'initial' and 'subsequent' rates of ingested N is the sum of the previous terms and aNm -(1-bNr) Nl, where aNm is the intercept component representing maintenance losses of N at fasting and (1- bNr) NI is the quantity of fed N retained to replace maintenance N loss. 4. Application of the appropriate energetic forms of UmN and aNm, viz. Et aNp -Et (bNr-bNna) NI and EuaNm, to the expression for obtaining TME, demonstrated that TME exceeded MEc by the quantities Et (bNr-bNna) NI and EtaNp, for test food intakes resulting in 'initial' and 'subsequent' rates of food N, respectively. 5. Application of appropriate energetic components of the model to simulate correction of TME to ZNB, demonstrated TMEZNB to be a biased quantity, deviating from MEc by the amount -Eu (1-bnr) NI or expressed as an excreta energy slope component, bEu(1-bNrNI/GE)GE where Eu is an appropriate energy coefficient. An alternative perspective is that ZNB correction removes the energetic form of UmN as a source of bias, but introduces one related to EuaNm. Its nature may be perceived by regarding TME as a function of a regression line relating energy excreted (EE) to energy ingested that has been corrected for UmN energetic bias and is pivoting on a fulcrum vertically aligned with the position of ZNB on the GE (x) axis. The regression line rotates anti-clockwise in response to ZNB correction by an amount equal to the magnitude of EuaNm measured on the EE (y) axis from the point of interception. 6. The study identified processes that may be employed to remove bias and improve precision of TME.     

A comparative study between mature ostriches (Struthio camelus) and adult cockerels with respect to true and apparent metabolisable energy values for maize,barley, oats and triticale

1. In three successive trials with cockerels and mature ostrich males the apparent and true metabolisable energy values, corrected for nitrogen retention (AME_n and TME_n) were determined by a balance method for malting barley, oats, triticale and yellow maize. All these ingredients were used as sole dietary components with the exception of triticale for ostriches which was diluted with 440 g/kg lucerne meal. The balance trial lasted for 5 d after an adaption period of 7 d for ostriches, and 3 d after an adaption period of one day for cockerels.

2. AME_n values for cockerels of malting barley, oats, triticale and maize were 11.6, 10.48, 11.44 and 14.42 MJ/kg respectively. Significantly higher values of 14.21, 12.65, 12.60 and 14.89 MJ/kg were determined for malting barley, oats, triticale and maize for ostriches.

3. TME_n values determined by regression yielded values in ostriches of 13.92, 12.27, 13.21 and 15.22 MJ/kg for malting barley, oats, triticale and maize respectively. The corresponding TME_n values in cockerels were 11.33, 10.63, 11.82 and 14.07 MJ/kg.

4. The ostrich is capable of utilising fibre more efficiently than poultry. The higher energy values observed for the various ingredients also indicated that the non‐starch polysaccharides such as ß‐glucans and arabinoxylans in the more fibrous energy sources had little if any effect on the available energy of these ingredients as found with poultry.

5. The potential of ostriches to utilise the more fibrous energy sources like barley, oats and triticale allows for their economical use in diet formulation. This possibility may result in markedly lower food costs for ostriches.     

Comparative apparent metabolisable energy values of high, medium and low tannin varieties of sorghum in cockerel, guinea fowl and quail

1. Nitrogen-corrected apparent metabolisable energy values (AMEN) of three varieties of sorghum (white-low tannin, brown-medium tannin and red-high tannin) were measured in three species of poultry (cockerel, guinea fowl and Japanese quail) by a practical diet replacement (total collection) method. 2. Each variety of sorghum was tested at two concentrations (200 and 400 g/kg of reference diet) in 6 replications with one cockerel or guinea fowl or two quails per replication. The duration of the trial included a 10 d preliminary feeding period (on conventional grower diet) followed by a 12 d adaptation period (on reference and test diets) and a 3 d balance period (with recording of feed intake and excreta output). 3. The calculated AMEN values of different sorghum varieties were: white--12.9, 12.8 and 12.7; brown--12.7, 12.3 and 12.6; and red--11.4, 11.1 and 11.6 MJ/kg for cockerels, guinea fowls and quails, respectively. The mean AMEN value of red sorghum (11.3 MJ/kg) was significantly lower than those of brown (12.5 MJ/kg) or white sorghum (12.8 MJ/kg). A negative correlation was observed between tannin concentration and AMEN. 4. There was no significant difference in the AMEN values of white, brown and red sorghum varieties to the different poultry species. AMEN values of sorghum for the cockerel could, therefore, be used in practical feed formulation for guinea fowl and quail.