Ruminal degradability and in vitro intestinal digestibility of sunflower meal and in vitro digestibility of olive by-products supplemented with urea or sunflower meal: Comparison between goats and sheep

The in vitro digestibility of two-stage dried olive cake (TSDOC) and olive leaves (OL) unsupplemented or supplemented with increasing amounts of urea (U) or sunflower meal (SM) (0, 1.5, 2 and 2.5 g/100 g organic matter (OM) of the by-product) was determined. Chemical and amino acid composition, in vitro digestibility, in situ rumen degradability of crude protein and amino acids, and in situ–in vitro intestinal digestibility of SM CP and amino acids was determined. The in sacco rumen degradability and in vitro intestinal availability of CP and individual amino acids were also determined. Results obtained in Granadina goats and Segureña wethers were compared. SM provides arginine, glycine and aspartic and glutamic acids. The addition of increasing amounts of U or SM improved (P<0.001) the IVDMD and IVOMD of both TSDOC and OL. There was no effect (P>0.05) of the rumen inoculum origin on in vitro TSDOC digestibility. In contrast, values for OL were higher (P<0.001) for goats versus sheep. In sacco ruminal CP degradability of SM was relatively high, and similar in sheep and goats (ED=0.78 and 0.75 for sheep and goats). Individual amino acid ruminal degradability had different values, being lowest for methionine, leucine, proline, tyrosine and cysteine. Values obtained for individual amino acids differed from those of CP. Apparent intestinal digestibility of undegraded protein (AIDUP) of SM was high (0.86 and 0.98, respectively, for sheep and goats). The intestinally absorbable protein (IADP) was low (18.9 and 24.0 for sheep and goats, respectively). Results indicate that goats and sheep have the same capacity for TSDOC digestion, but goats showed a better capacity than sheep for OL utilisation. Although the amino acids supply to the intestine from SM is not important it could be a good supplement for low degradable protein feedstuffs such as TSDOC and OL.     

Effect of the proportions of neutral detergent fibre and starch, and their degradation rates, on in vitro ruminal fermentation

Effects of proportions of neutral detergent fibre (aNDFom) and starch, as well as their degradation rates, on rumen fermentation were tested using an in vitro rumen simulation system (SIMCO). The in vitro system was designed to simulate selective particle retention and had an average fluid volume of 1150 ml with a liquid dilution rate of approximately 0.07 h⁻¹. Two types of hay (aNDFom sources) and two types of starch were each included at two different levels in the diet and were examined in an experiment following a 2×2×2 factorial arrangement of treatments (eight diet combinations). The hay was either late-cut timothy (Phleum pretense L.) or early cut meadow grass (Poa pratensis L.), with ruminal in situ aNDFom digestion rates of 0.03–0.04 and 0.07–0.08 h⁻¹, respectively. The two starch types were raw (R) and cooked (C) potato starch with previously determined in vitro ruminal digestion rates of 0.04 and 0.20 h⁻¹, respectively. The starch levels were 300 and 600 g/kg diet dry matter (DM) with the remaining being hay (282–682 g/kg DM) and peptone (14–111 g/kg DM). The aNDFom level varied among the diets with different starch levels and hay types. The peptone acted as a source of peptides and, together with ammonia salts from buffer, was used to balance the N contents of the diets. The feeding level for each of the eight vessels was 28 g DM/d. Two 10-day simulations were made with the system. The average pH was higher (P<0.05) for all treatments with raw potato starch (6.19) versus cooked starch (6.07). Protozoa scores, on a qualitative scale, declined faster at the higher starch level. The aNDFom digestibility was, as expected, higher (P<0.001) for meadow hay (0.57) than timothy (0.32), and was also higher (P<0.001) at the lower starch level (0.54) versus the higher (0.35). Microbial protein production efficiency (mg microbial N/g organic matter truly digested) was higher for the faster degrading aNDFom (P<0.01) and starch (P<0.05) sources, but was not affected by starch level. Cooked starch resulted in a lower acetate proportion (449 mmol/mol versus 591 mmol/mol VFA; P<0.001) but higher proportions of propionate (297 mmol/mol versus 236 mmol/mol VFA; P<0.001), and butyrate (169 mmol/mol versus 127 mmol/mol VFA; P<0.01). Butyrate increased with starch level (127 mmol/mol versus 169 mmol/mol VFA; P<0.01), and was also higher for meadow hay versus timothy (168 mmol/mol versus 128 mmol/mol VFA; P<0.01). Interactions between the treatments demonstrate that the response in VFA pattern to starch level is dependent on starch and aNDFom sources. Substrates such as starch and aNDFom are fermented differently depending on their rates of ruminal degradation.     

The influence of addition of gallic acid, tannic acid, or quebracho tannins to alfalfa hay on in vitro rumen fermentation and microbial protein synthesis

Tannins may reduce rumen degradability of protein, increase the proportion of feed protein reaching the lower digestive tract for enzymatic digestion and thereby increase the efficiency of protein utilization. The objective was to assess the effects of different types and levels of tannins on rumen in vitro gas production and its kinetics, in vitro true degradability (IVTD) and rumen degradability of protein (IVRDP), and microbial protein synthesis by incubating alfalfa (Medicago sativa L.) hay in buffered rumen fluid. Alfalfa was incubated in buffered rumen fluid with and without the addition of different levels of gallic acid (GA), quebracho tannin (QT), or tannic acid (TA). Tannins at the lower inclusion levels had minimal effects on fermentation products compared to the higher levels. Addition of QT and TA reduced ammonium-N (NH₄⁺-N) concentration. Addition of QT at 20, 40, and 60 g/kg DM decreased NH₄⁺-N by 2, 7, and 12% compared with control whereas addition of TA reduced NH₄⁺-N by 5, 6, and 12% when added at 20, 40 and 60 g/kg DM, respectively. In experiment 2, addition of QT at 50, 100, and 150 g/kg DM, resulted in reduction of NH₄⁺-N by 12, 30, and 51%, respectively, compared with the control. Addition of TA at 50, 100, and 150 g/kd DM reduced NH₄⁺-N by 14, 26, and 47% compared with control. Inclusion of QT at 50, 100, 150 DM reduced IVRDP by 13, 30, and 36% compared with control whereas at these levels of inclusion, TA resulted in reduction of IVRDP by 14, 25, and 48%. Rate of gas production decreased (P<0.001), while asymptotic gas production increased (P<0.0001) with increasing level of GA and TA. Quebracho tannin decreased (P<0.0001) both the rate and asymptotic of gas production. Gallic acid had a positive effect on fermentation as indicated by increased gas production and total short chain fatty acids (SCFA) production. Quebracho tannin decreased 24 h gas production, IVTD, and total SCFA production. Acetate to propionate ratio increased with the addition of GA and but decreased when QT was added. Addition of tannins did not markedly increase total purines but numerical values tended to be higher in the presence of tannins compared with the control. Efficiency of microbial growth was lower in the presence of GA and unaltered by TA, but higher in the presence of QT compared with the control. The effect of tannins on rumen fermentation and protein degradation varied with type and level of tannins. In vivo studies will be conducted to validate the in vitro results.     

Effects of exogenous fibrolytic enzymes on ruminal fermentation and digestibility of total mixed rations fed to lambs

This experiment was designed to study effects of exogenous fibrolytic enzymes on digestibility and ruminal fermentation of total mixed rations (TMR) with different forage:concentrate (F:C) ratios. The experimental design was a 6×6 Latin square with six ruminally cannulated Ramboulliet lambs (58 ± 7.4 kg body weight) used in a 3×2 factorial arrangement of treatments using three forage:concentrate (F:C) ratios (400:600, 500:500, 600:400 kg/kg) and two (0 or 2 g) levels of fibrolytic enzymes/kg TMR dry matter (DM). Exogenous fibrolytic enzymes increased the soluble fraction of DM (P<0.01) and ruminal in situ disappearance rate of DM and neutral detergent fibre (aNDF; P<0.001). However, there were no differences among treatments in DM and aNDF in vivo digestibility due to enzyme addition to the diet. Feed intake and N balance were also not affected by enzymes, and ruminal fermentation patterns were unchanged. Exogenous fibrolytic enzymes improved ruminal disappearance rates of DM and aNDF, but had no impact on lamb performance or ruminal fermentation.     

Chemical composition and in vitro fermentation of tannin-rich tree fruits

Dry and mature tree fruits are a potential source of protein for goats in the semi-arid areas of southern Africa, but their chemical composition and feeding value is largely unknown. This study presents the chemical composition and in vitro fermentation of indehiscent whole fruits and separated seed and hull fractions from Acacia nilotica, Acacia erubescens, Acacia sieberiana, Acacia erioloba, Piliostigma thonningii and Dichrostachys cinerea trees. Results indicate that the N contents of whole fruits ranged between 13.5 g/kg DM (A. nilotica) and 27.1 g/kg DM (A. erubescens). Seeds had a higher N content than hulls for all tree species. A. nilotica, D. cinerea and P. thonningii fruits had high levels of extractable phenolics (758, 458 and 299 g/kg DM, respectively). Soluble phenolics (SPh) and ytterbium precipitable phenolics (YbPh) levels were negatively correlated to in vitro gas production but positively correlated to in vitro organic matter degradability (iOMD). Partition factors for whole fruits at 48 h ranged between 3.6 mg/ml for A. erioloba and 7.8 mg/ml for A. nilotica. Seeds of A. erioloba, A. erubescens and P. thonningii were consistently fermented more efficiently throughout the incubation period compared to their whole fruits or hulls. Estimating in vitro degradability of phenolic-rich substrates through filtration procedures can give erroneous results due to the loss of soluble phenolics, which are not necessarily degradable. The feeding value of fruits from D. cinerea and A. nilotica tree species may be reduced due to the presence of high levels of phenolics.     

Effects of feeding supplemental palmitic acid (C16:0) on performance and milk fatty acid profile of lactating dairy cows under summer heat

The objective was to determine performance and milk fatty acid changes of high producing dairy cows in early lactation, under summer heat, by adding a supplemental rumen inert fat in the form of a saturated free fatty acid (856 g/kg C16:0/kg of total fatty acids) to the total mixed ration (TMR). Early lactation multiparous Holstein cows in two similar pens of 99 and 115 cows were used in a 2 × 2 Latin Square design experiment with 35 d periods during a period when daily high and low temperatures averaged 34.3 and 15.9 °C, the relative humidity averaged 51% and there were no rain events. The TMR was the same for both groups, consisting of approximately 435 g/kg forage and 565 g/kg concentrate, except that the vitamin/mineral premix had no added fat (control, C) or added fat (C16:0) at a level designed to deliver approximately 450 g/cow/d of supplemental fat if cows consumed 26.5 kg/d of dry matter (DM). The two TMR averaged 905 g/kg organic matter (OM), 318 g/kg neutral detergent fiber (aNDF), and 186 g/kg crude protein (CP). The ‘C’ TMR had 58 g/kg total fatty acids with an estimated net energy for lactation (NE_l) of 7.3 MJ/kg (DM), while the C16:0 TMR had 72 g/kg total fatty acids and 7.5 MJ/kg NE_l (DM). Whole tract digestibility of DM, OM, aNDF and CP tended (P<0.10) to increase, and that of fatty acids increased substantially (P<0.01), with C16:0 feeding, whereas, DM intake was not affected. Milk fat content decreased (P<0.01) with C16:0 feeding (37.5 versus 36.0 g/kg), whereas, true protein content tended (P=0.09) to increase. There was a tendency (P=0.07) for increased milk yield (36.69 versus 38.04 kg/d), while milk protein yield increased (P=0.03) with C16:0 supplementation (1.08 versus 1.13 kg/d). Milk fat yield was unaffected by treatment. Concentrations of short and medium chain milk fatty acids (C6:0–C15:0), decreased, or tended to decrease, with C16:0 addition (C13:0 and C15:0, P<0.10; all others, P≤0.05). The concentration of C16:0 increased (P<0.001) in milk triglycerides from cows fed C16:0 (27.10 versus 31.57 g/kg), the longer chain saturated fatty acids C17:0 and C18:0 decreased (P≤0.05) and other long chain unsaturated fatty acids were unaffected. Benefits of C16:0 feeding on cow productivity must be balanced against negative effects on the nutritive value of the milk (i.e., increased C16:0 in milk fatty acids) produced for human consumption. However, relatively low amounts of supplemental C16:0 (27.10 versus 31.57 g/kg in milk triglycerides for C and C16:0 supplemented cows, respectively) were actually secreted in milk, in spite of them being essentially fully digested in the digestive tract. Strategies to divide cows into production groups based on milk yield and/or milk fat proportions could further limit C16:0 secretion in milk. Supplemental dietary C16:0 may have positive effects on milk production that outweigh the negative health effects of the increased C16:0 content in the milk fat.     

Relationships between kernel vitreousness and dry matter degradability for diverse corn germplasm: II. Ruminal and post-ruminal degradabilities

Correlations between kernel vitreousness and ruminal in situ (RDMD) and total tract dry matter (TDMD; sum of ruminal in situ and post-ruminal in vitro measurements) degradabilities were determined for 33 diverse corn germplasm sources. These included a wide range of endosperm characteristics from opaque 2 (o2) types to densely packed flint types, and a number of intermediates. Harvests were done at two growth stages; 1/2 milk-line (ML) and black-layer (BL). Kernels from middle portion of ears were oven dried at 40 °C for 72 h and ground through a Wiley mill (6 mm screen) for measurement of in situ RDMD after 0 and 14 h of incubation using two steers (1.5 g/bag × 8 replicates per time point per steer in 5 cm × 5 cm bags of 50 μm pore size). Residue from the 14 h bags proceeded to an 8 h in vitro enzymatic post-ruminal digestion after which the residue was oven dried at 62 °C for 48 h and dry matter content determined. Inbred by harvest-stage interactions were observed for 0-h disappearance and TDMD. Vitreousness had strong negative correlations with degradability measurements, particularly for more mature (BL) samples (−0.728, −0.770 and −0.603) versus ML (−0.569, −0.541 and −0.338) for 0 h disappearance, RDMD and TDMD, respectively. Vitreousness was highly correlated with corn degradability, especially at a black-layer stage of harvest, in this diverse corn germplasm.     

The digestion of dietary protein bound by condensed tannins in the gastro-intestinal tract of sheep

The digestion of dietary protein bound by condensed tannins (CTs) in ruminants was investigated by determining the extent of dissociation of insoluble ¹²⁵I-BSA + CT complexes administered to abomasally and intestinally fistulated sheep. The extent of dissociation was registered as the true digestibility of iodinated bovine serum albumin (¹²⁵I-BSA). The true digestibility of ¹²⁵I-BSA originally bound to Leucaena pallida CT (0.721) was lower (P<0.05) than that of ¹²⁵I-BSA originally bound to L. leucocephala CT (0.880) between the abomasum and terminal ileum. These results indicate that differences in the ability of CT to inhibit ¹²⁵I-BSA digestion in vivo matched the relative abilities of the same CT to bind BSA in vitro, indicating that the in vitro BSA-binding assay for ranking CT behaviour was biologically relevant in vivo. Furthermore, the true digestibility of CT-bound ¹²⁵I-BSA between the mouth and faeces permitted the prediction of the quantitative contribution that CT-bound dietary proteins make to improved nitrogen supply to the small intestines.     

Effect of feeding Leucaena leucocephala leaves and twigs on energy utilization by goats

Fifteen intact male goats of Jamunapari breeds, 12–15 months old weighing 22.0 kg were divided into three groups of five animals in each in a completely randomized design to determine the effect of feeding Leucaena leucocephala leaves and twigs (LLLT) on heat production (HP) and energy balance (EB). Animals in treatment I (Control) was supplied with a conventional ration consisting of a concentrate mixture and vegetative parts of Zea mays and in treatments II and III received similar rations except that LLLT provided about 0.40 and 0.50 parts crude protein (CP) of total protein in ration, respectively by replacing 0.50 and 1.00 parts each of the solvent extracted groundnut cake and wheat bran in the concentrate mixture, respectively. The dry matter (DM) supplemented through LLLT was 0, 121 and 224 g in treatments I, II and III, respectively and it corresponds to 0, 0.19 and 0.34 parts of total DM intake. Supplementation of increasing amount of LLLT did not affect (P=0.303) DM intake but digestibility of DM decreased (P=0.002) linearly. The digestible energy (DE) intake was not affected (P=0.161) due to supplementation of LLLT. Urinary energy (UE) loss per kg metabolic body size per day and as proportion of gross energy (GE) or DE intake increased (P<0.001) linearly with increased LLLT supplementation. Average methane production varied from 15.2 to 17.3 L/d. Methane energy loss per kg metabolic body size per day decreased (P=0.024) linearly with increased supplementation of LLLT, however, as proportion of GE or DE did not show any effect of treatment. Metabolizable energy (ME) intake per kg metabolic body size per day was unaffected (P=0.113) by the treatments which corresponded to 1.63, 1.35 and 1.38 times of maintenance in treatments I, II and III, respectively indicated that animals were in well-fed condition. Heat production (HP) and energy balance (EB) were not affected by the supplementation treatment. It is concluded that supplementation of 224 g of LLLT in the diet of goats, which provided DM at a proportion of 0.34 or CP at a proportion of 0.59, did not affect HP and EB.     

Effects of formaldehyde treated mustard cake and molasses supplementation on nutrient utilization, microbial protein supply and feed efficiency in growing kids

Twenty healthy growing male kids (Sannen × Beetal and Alpine × Beetal) of 2–3 months of age, weighing 12 ± 0.61 kg, were randomly assigned to one to four dietary treatments in a 2 × 2 factorial design. Two types of isonitrogenous and isocaloric concentrate mixtures were fed to kids in four treatments being: untreated mustard cake, untreated mustard cake with molasses, formaldehyde treated mustard cake and formaldehyde treated mustard cake with molasses. Both concentrate mixtures were similar in composition with the only difference in RDP and UDP due to replacement of untreated mustard cake by formaldehyde (FA) treated mustard cake. Kids were fed concentrate and forage (berseem hay:wheat straw = 2:1) in a 50:50 ratio. A metabolism experiment of 7 days duration was conducted before the end of the experiment. Kids were housed in individual pens and fed experimental diets for 120 days. No differences occurred in digestibility of DM, OM, CP and NDF_om, but ether extract digestion in kids fed FA treated mustard cake was higher (P<0.05). Supplementation of molasses increased apparent nutrient digestibility, without influencing digestion of CP and NDF_om. Intake of DM, CP and ME did not differ among treatments. The CP content of the diet actually consumed that was supplemented with molasses was lower (P<0.01), with a higher (P<0.01) ME content, without influence of FA treatment on nutritive level of the diet consumed. N balance was higher (P<0.01) in kids fed FA treated MC and supplemental molasses. Microbial protein yield, calculated from purine derivatives excreted in urine, was similar among treatments. The DM intake in the growth experiment was higher by feeding both FA treated MC and molasses. Average daily gain was influenced by feeding FA treated MC, without any effect of supplemental molasses on growth rate of the kids. The higher DM intake and improved growth rate in kids fed FA treated MC resulted better feed efficiency. Higher UDP intake improved growth performance in kids and supplementation of molasses, with or without ruminal escape CP, has no added advantage.     

The potential of Commelina benghalensis as a forage for ruminants

To evaluate the potential of Commelina benghalensis as a forage for ruminants, effects of plant maturity on chemical composition, rumen degradability as well as its increased dietary inclusion level on intake, digestibility and N balance in sheep fed Sorghum almum were investigated with forage obtained from the wild, re-established and harvested at 6, 10 and 14 weeks of growth. Composite herbage samples were analyzed for dry matter (DM), chemical components, total extractable phenolics (TEP) and amino acid content. In sacco rumen degradability measurements used six individually confined wethers (8 ± 0.5 months of age; 21 ± 2.6 kg live-weight (LW)) fitted with rumen cannulae and fed a ration of 3:1 fresh S. almum and Medicago sativa hay (about 1:2 on a DM basis). In sacco bags containing 5 g each of dry herbage were inserted into the rumen and withdrawn sequentially after 0, 12, 24, 36 and 48 h. Metabolizable energy (ME) was estimated from 24 h in vitro gas production. In the digestibility study, 12 wethers fitted with rumen canula were housed in metabolic crates and allotted to four treatment diets (i. e., D0, D10, D20 and D30) constituted from fresh S. almum and pre-wilted C. benghalensis in a randomized complete block design. The control diet (D0) was 3 kg fresh S. almum (≈535.5 g DM/wether/d about 30 g/kg LW), whereas D10, D20 and D30 were D0 +300, 600 or 900 g of wilted C. benghalensis (≈34, 68 or about 102 g DM/wether/d), respectively. The study lasted for 21 d. Dry matter, fibre and TEP content increased (P<0.001) with maturity of the forage, whereas those of CP and EE decreased (P<0.0001) over the same period. Amino acids (AA) also declined with maturity (P<0.05). Rumen degradability of DM and OM were unaffected, but DM intake increased linearly (P<0.0001) at a decreasing rate (Q: P<0.05) and DM digestibility (DMD) and N intake increased linearly (P<0.01 and P<0.0001, respectively) as level of C. benghalensis in the diet increased. Results indicate that advancing maturity affected chemical composition, but not rumen degradability, of C. benghalensis and also demonstrated that inclusion of C. benghalensis in S. almum diet improved intake, digestibility and N intake, suggesting its potential use as a feed supplement.     

Nutritional characterization of some tropical urban market crop wastes

Market crop wastes of banana (Musa acuminata) leaves and pseudo-stem sheaths, sweet potato (Ipomoea batatas) vines and Solanum aethiopicum (traditionally known as nakati) were collected from three major markets in Kampala (Uganda). The wastes were evaluated for chemical composition during the dry and wet seasons, rumen degradation using three cannulated indigenous mature ewes, and digestibility using 12 indigenous intact growing male goats, 4–6 months old and weighing 15.8 kg (S.D. 2.1). The goats in the digestibility study were kept in metabolism cages and fed the wastes as sole diets, either fresh or wilted.

Mean dry matter (DM) content was 97, 121, 197 and 216 g/kg for pseudo-stem sheaths, nakati, sweet potato vines and banana leaves, respectively. Crude protein (CP) was 34, 109, 112 and 114 g/kg DM for pseudo-stem sheaths, banana leaves, sweet potato vines and nakati, respectively. The chemical composition was similar among seasons and markets for the banana based wastes. However, for sweet potato vines and nakati, the wet season wastes had significantly higher CP and lower NDFom and ADFom. Chemical composition was different (P<0.05) among the markets for nakati. Effective degradability differed (P<0.05) between the wastes, averaging 0.43 (banana leaves), 0.47 (pseudo-stem sheaths) and 0.56 (nakati) to 0.69 g/g DM incubated (sweet potato vines). DM intake, N retention and digestibility were not significantly affected by wilting. Average DM intake was 176, 270 and 559 g/day; CP intake was 26, 30 and 63 g/day, while metabolizable energy (ME) intake was 1.3, 1.7 and 5.1 MJ/day for nakati, banana leaves and sweet potato vines, respectively. N retention (as a fraction of N intake) was −0.51 (banana leaves), 0.62 (nakati) and 0.39 (sweet potato vines). The organic matter (OM) and CP digestibilities of banana leaves were low, averaging 0.52 and 0.49, respectively. The high moisture content of nakati wastes resulted in low intake, whereas banana leaves had a low degradation rate and a low N retention. Market sweet potato vine wastes were sufficient to provide the CP and ME required by growing goats under tropical conditions.     

True phosphorus digestibility and the endogenous phosphorus outputs associated with brown rice for weanling pigs measured by the simple linear regression analysis technique

The objectives of this study were to determine true phosphorus (P) digestibility, degradability of phytate-P complex and the endogenous P outputs associated with brown rice feeding in weanling pigs by using the simple linear regression analysis technique. Six barrows with an average initial body weight of 12.5 kg were fitted with a T-cannula and fed six diets according to a 6 × 6 Latin-square design. Six maize starch-based diets, containing six levels of P at 0.80, 1.36, 1.93, 2.49, 3.04, and 3.61 g/kg per kg dry-matter (DM) intake (DMI), were formulated with brown rice. Each experimental period lasted 10 days. After a 7-day adaptation, all faecal samples were collected on days 8 and 9. Ileal digesta samples were collected for a total of 24 h on day 10. The apparent ileal and faecal P digestibility values of brown rice were affected ( P < 0.01) by the P contents in the assay diets. The apparent ileal and faecal P digestibility values increased from − 48.0 to 36.7% and from − 35.6 to 40.0%, respectively, as P content increased from 0.80 to 3.61 g/kg DMI. Linear relationships ( P < 0.05), expressed as g/kg DMI, between the apparent ileal and faecal digestible P and dietary levels of P, suggested that true P digestibility and the endogenous P outputs associated with brown rice feeding could be determined by using the simple regression analysis technique. There were no differences ( P>0.05) in true P digestibility values (57.7 ± 5.4 v. 58.2 ± 5.9%), phytate P degradability (76.4 ± 6.7 v. 79.0 ± 4.4%) and the endogenous P outputs (0.812 ± 0..096 v. 0.725 ± 0.083 g/kg DMI) between the ileal and the faecal levels. The endogenous faecal P output represented 14 and 25% of the National Research Council (1998) recommended daily total and available P requirements in the weanling pig, respectively. About 58% of the total P in brown rice could be digested and absorbed by the weanling pig. Our results suggest that the large intestine of the weanling pigs does not play a significant role in the digestion of P in brown rice. Diet formulation on the basis of total or apparent P digestibility with brown rice may lead to P overfeeding and excessive P excretion in pigs.     

The effects of in vivo and in vitro non-enzymatic glycosylation and glycoxidation on physico-chemical properties of haemoglobin in control and diabetic patients

The erythrocyte deformability, which is related to erythrocyte internal viscosity, was suggested to depend upon the physico-chemical properties of haemoglobin. In the present study we employed ESR spectroscopy in order to explore further the extent to which the in vivo or in vitro glycation and/or glycoxidation might affect haemoglobin structure and conformation. We revealed that under both in vivo and in vitro conditions the attachment of glucose induced a mobilization of thiol groups in the selected domains of haemoglobin molecules (the increased h₊₁/h₀ parameter of maleimide spin label, MSL; 0.377 ± 0.021 in diabetics vs 0.338 ± 0.017 in controls, n = 12, P < 0.0001). The relative rotational correlation time (τ_c) of two spin labels, TEMPONE and TEMPAMINE, respectively, in erythrocyte insides (5.22 ± 0.42 in diabetics, n = 21 vs 4.79 ± 0.38, n = 16 in controls, P < 0.005) and in the solutions of in vitro glycated haemoglobin, were increased. Neither oxidation nor crosslinking of thiol groups was evidenced in glycated and/or oxidized haemoglobin. In addition, erythrocyte deformability was found to be reduced in type 2 diabetic patients (6.71 ± 1.08, n = 28 vs 7.31 ± 0.96, n = 21, P < 0.015). In conclusion, these observations suggest that: the attachment of glucose to haemoglobin might have decreased the mobility of the Lys-adjacent Cys residues, thus leading to the increased h₊₁/h₀ parameter of MSL. Such structural changes in haemoglobin owing to non-enzymatic glycosylation may contribute to the increased viscosity of haemoglobin solutions (r = 0.497, P < 0.0035) and the enhanced internal viscosity of diabetic erythrocytes (r = 0.503, P < 0.003). We argue that such changes in haemoglobin, and consequently in red blood cells, might contribute to the handicapped oxygen release under tissue hypoxia in the diabetic state.     

Effects of Acacia nilotica, A. polyacantha and Leucaena leucocephala leaf meal supplementation on performance of Small East African goats fed native pasture hay basal forages

Optimal utilisation of tannin-rich browse tree fodders including Acacia spp. foliages as crude protein (CP) supplements to ruminants in the tropics is limited by less available information on their feed nutritive potential. Two studies were conducted to: (1) determine rate and extent of ruminal dry matter (DM) degradability (DMD) and (2) investigate effect of sun-dried Acacia nilotica (NLM), A. polyacantha (PLM) and Leucaena leucocephala leaf meal (LLM) supplementation on growth performance of 20 growing (7–9 months old) Small East African male goats (14.6 ± 0.68 kg) fed on native pasture hay (NPH) basal diet for 84 days in a completely randomised design experiment in north-western Tanzania. The goats were randomised into four treatment groups consisting of five animals each. Three supplement diets: 115.3 g NLM (T₂), 125.9 g PLM (T₃) and 124.1 g LLM (T₄), which was used as a positive control, were supplemented at 20% of the expected DM intake (DMI; i.e., 3% body weight) to the three animal groups fed on NPH (basal diet) compared to the animals in a control group that were fed on NPH without browse supplementation (T₁).

NPH had significantly the lowest (P < 0.05) CP of 45.5 g kg⁻¹ DM compared to NLM, PLM and LLM (159, 195 and 187 g kg⁻¹ DM, respectively). NPH had higher (P < 0.05) fibre fractions; lower ruminal DM degradability characteristics and ME than NLM, PLM and LLM. Supplementation of the animals with browse resulted to (P < 0.05) higher average daily weight gains (ADG) of 157.1 g day⁻¹ in T₄ than the animals fed on T₂ (114.3 g day⁻¹) and T₃ (42.9 g day⁻¹), and even to those fed on T₁ (control), which lost weight (−71.4 g day⁻¹). Improved weight gains were mainly due to corrected feed nitrogen (N) or CP due to supplementation of the animals with browse fodder. Too low CP of the NPH would not meet the normal requirements of CP (80 g CP kg⁻¹ DM) for optimal rumen microbial function in ruminants. Higher ADG due to LLM (T₄) and NLM (T₂) supplementation suggest optimised weight gains due to browse supplementation (20% of expected DMI); while lower weight gains from supplementation with PLM (T₃) indicate the possible utilisation of A. polyacantha leaves to overcome weight losses especially during dry seasons.     

Conversion of Japanese red cedar (Cryptomeria japonica) into a feed for ruminants by white-rot basidiomycetes

The potential of five white-rot fungi to convert Japanese red cedar (Cryptomeria japonica) into feed for ruminants was determined. Pleurotus ostreatus (ATCC 66376), Pholiota nameko (IFO 30373), Dichomitus squalens (CBS 432.34), Lentinula edodes (IFO 6654) and Ceriporiopsis subvermispora (ATCC 90467) were inoculated into chips of cedar sapwood. L. edodes was cultured at 25 °C, and the other fungi at 28 °C, for 4, 8, 12, or 20 weeks. The in vitro organic matter (OM) digestibility (IVOMD) in cedar wood cultured without fungus were between 0.047 and 0.068, while it was elevated to 0.446 by culturing with C. subvermispora and to 0.281 by culturing with L. edodes for 20 weeks. In contrast, the IVOMD were 0.200, or lower, in cedar wood cultured with P. ostreatus, P. nameko, or D. squalens. The in vitro gas production (IVGP) in cedar wood cultured with P. ostreatus, P. nameko, or D. squalens was 37 ml/g OM, or lower, while that in cedar not inoculated with fungus was between 4 and 17 ml/g OM. In contrast, the IVGP in cedar wood cultured with C. subvermispora for 20 weeks increased to 107 ml/g OM, and that in cedar wood cultured with L. edodes increased to 58 ml/g OM. Lignin degradability in cedar wood cultured with C. subvermispora and L. edodes for 20 weeks were 0.578 and 0.288, respectively. These changes in IVOMD and IVGP demonstrate that a selective white-rot fungus, C. subvermispora has the ability to convert cedar wood into feed for ruminants, although further increase is required before the cultured cedar wood would have widespread feed potential.     

Ecdysterone induced sexual reproduction in Opalina sudafricana parasitic in Bufo regularis

Ecdysterone induced sexual reproduction in Opalina sudafricana parasitic in Bufo regularis. International Journal for Parasitology 3: 863–868. Ecdysterone injections (0·5 mg/ml) induced sexual reproduction in Opalina sudafricana parasitic in male or female Bufo regularis after 12 days. Hypophysectomy or gonadectomy did not prevent the hormone from producing its effect on the parasites. Ecdysterone did not induce sexual reproduction in the parasites in vitro. Urine of toads injected with ecdysterone induced the opalinids to encyst in vitro.     

Effects of Brosimum alicastrum and Lysiloma latisiliquum mixtures on voluntary intake, nutrient digestibility and nitrogen balance in sheep fed tropical pastures

Effects of supplementing tree foliage mixtures on voluntary intake, apparent digestibility and N balance was evaluated using Pelibuey sheep fed low quality diets. Five treatments were examined in a 5 × 5 Latin square design, which consisted of a basal diet of grass (Sorghum halepense) hay supplemented with Brosimum alicastrum (B) and Lysiloma latisiliquum (L) at the following rates (g DM/kg diet): B264, L0; B198, L66; B132, L132; B66, L198 and B0, L264. Additionally, an in situ degradability evaluation was completed with two ruminally cannulated cows. Neutral detergent fibre (NDF), acid detergent insoluble N (ADIN), lignin(sa) and total phenols (TP) were higher (P<0.01) in L. latisiliquum versus B. alicastrum. Daily intake (g/kg LW^0.75/day) of DM (from 98 to 73) and OM (from 88 to 66) decreased quadratically (P<0.01), whereas CP (from 8.0 to 5.6) and ME (from 7.7 to 5.2, MJ/sheep/day) reduced linearly (P<0.01), as L. latisiliquum increased in the diet. Apparent digestibility of DM (from 0.486 to 0.445), OM (from 0.511 to 0.458) and CP (from 0.417 to 0.198) decreased linearly (P<0.01) and was associated with a low ruminal in situ CP degradability of L. latisiliquum. The decrease in N intake and digestibility induced lower (P<0.01) N retention (from 2.7 to 0.1 g/sheep/day). Although the incremental substitution of B. alicastrum with L. latisiliquum negatively affected intake, rumen degradation, digestibility and N balance, results indicate that this foliage mixture, but with no more than 132 g DM/kg diet of L. latisiliquum, could be used as a supplementation strategy to sheep fed low quality forage without negative effects on voluntary intake.     

Effect of the level of dry matter and protein and degradation rate of starch on in vitro ruminal fermentation

Effects of starch type, feeding level and level of a mixed N source upon rumen fermentation were examined using an in vitro rumen simulation system (i.e., SIMCO) with a fluid volume of 1100 ml and liquid dilution rate of approximately 0.07/h. Two sources of starch, two feeding levels and two levels of N were examined in an experiment following a 2 × 2 × 2 factorial arrangement of treatments. The starch sources were raw slowly degrading (R), and cooked fast degrading (C), potato starch and constituted 450 g/kg diet dry matter (DM). The remaining was supplied in the form of a grass hay mixture. The feeding levels were 20 (DM20) and 40 (DM40) g DM/d and the diet N level was either low (N1) or high (N2), using peptone and ammonia salt additions in the buffer. Two simulations of 10 days each were completed. The amount of bicarbonate in buffer was varied according to feeding level, and pH (average 6.3) did not differ between treatments. An increased degradation rate of starch (R vs. C) depressed neutral detergent fibre (aNDFom) digestibility (0.46 vs. 0.36) and organic matter true digestibility (OMTD; 0.73 vs. 0.68), but there were no other treatment effects on digestibility. The VFA production efficiency (average 0.47 g VFA/g OMTD) was not affected by the main treatments, although an interaction between starch type and feeding level occurred. A decline in protozoa rating over the 10 day simulations was more apparent at the lower feeding level (DM20), indicating poor growth conditions for protozoa. Higher microbial efficiency (11.0 vs. 8.9 mg microbial N/g OMTD) and a higher proportion of propionate (272 vs. 207 mmol/mol VFA) occurred at DM20 compared to DM40. Increased degradation rate of starch (i.e., R vs. C) resulted in an improved microbial N efficiency (8.8 vs. 11.2 mg/g OMTD) and an increase in the proportion of propionate (226 vs. 253 mmol/mol VFA) at the expense of acetate (610 vs. 591 mmol/mol VFA). Increasing the level of N (i.e., N1 vs. N2) improved the microbial N efficiency (9.2 vs. 10.7 mg/g OMTD) and increased the proportion of propionate (230 vs. 249 mmol/mol VFA) and butyrate (100 vs. 119 mmol/mol VFA) at the expense of acetate (629 vs. 572 mmol/mol VFA). Interactions between starch type and N level upon VFA patterns were apparent. Results support earlier findings in that carbohydrate degradation rate is an important factor determining microbial growth rates and VFA distribution.     

Effect of rate of substitution of processed, urea-treated whole-crop wheat for grass silage on the intake, milk production and diet digestibility in dairy cows and ruminal metabolism in vitro

The effect of rate of substitution of processed, urea-treated whole-crop wheat (pWCW) for grass silage on intake, performance and whole-tract digestibility was evaluated using 44 dairy cows. Cows received 10.5 kg of concentrates per day and one of the following forage mixtures (dry matter (DM) basis): grass silage alone (W-0); 0.75 grass silage, 0.25 pWCW (W-25); 0.5 grass silage, 0.5 pWCW (W-50) or 0.25 grass silage, 0.75 pWCW (W-75). Forage DM intake increased linearly with inclusion rate of pWCW from 9.7 kg DM per day in cows fed W-0 to 14.6 kg DM per day in W-75. By contrast, milk and protein yield (kg/day) were higher (P < 0.05) in cows receiving W-25 compared with W-0, but there was no effect (P>0.05) of treatment on fat yield (kg/day). From week 11 of the experiment onwards, body condition score increased with rate of inclusion of pWCW (P < 0.05). Whole-tract apparent digestibility of organic matter (OM) and fibre (kg/kg), decreased linearly with rate of inclusion of pWCW. Assuming a constant digestibility of starch in the other diet components, the apparent digestibility of starch in pWCW was 0.95 kg/kg and was not affected by rate of inclusion (P>0.05). Four continuous culture vessels were used to determine the effect of rate of inclusion of pWCW on ruminal metabolism in four periods, each of 14 d duration with sampling conducted on days 9 to 14. Vessel ammonia concentration increased linearly (P < 0.05) with rate of inclusion of pWCW whilst mean pH tended (P = 0.06) to decrease. The ratio of acetate to propionate increased from 2.5 in vessels receiving W-0 to 3.2 in those receiving W-75 (P < 0.001). There was no effect (P>0.05) of treatment on digestibility (g/g) of OM, fibre or starch or microbial protein flow (g/day). It is concluded that forage DM intake increased linearly with rate of inclusion of pWCW, but there was no further improvement in milk yield from inclusion rates above 0.25 of the forage DM, with body condition score increasing instead. Increasing the inclusion rate of pWCW resulted in a more ketogenic volatile fatty acid profile but did not affect the efficiency of microbial protein synthesis when determined in vitro.