Fecal nitrogen to estimate intake and digestibility in grazing ruminants

This study aimed at evaluating forage intake and digestibility in ruminants using fecal nitrogen content, as well as validating a non-linear model to estimate digestibility in ruminants. A total of 58 conventional metabolism trials, carried out with sheep fed 27 forages (offered pure or in mixture) used in Rio Grande do Sul (RS) during the period 1969–1989 was analyzed. OM intake and OM digestibility (OMD) results were regressed linearly against fecal N, and OMD was also estimated from fecal crude protein (N × 6.25) content by a non-linear regression model. Fecal nitrogen excretion estimated forage intake in sheep with an R² = 0.73, whereas a low R² value of 0.36 was observed for OMD estimates. The equation obtained using the non-linear model was OMD = 0.7326 ? 0.3598 exp [(?0.9052 CP (g/kg OM))/100]. The parameters a (0.7326) and b (0.3598) estimated by the equation for all forages were significant (P<0.00001) and there was no effect of type of forage (P=0.38). The mean prediction error (MSPE), was 0.2379, indicating that the equation fit well to the data. The difference between estimated and observed organic matter digestibility was mainly caused by random variation (0.9765). The results indicated that the equation using the non-linear model developed with all forages can be used with enough precision to estimate the OM digestibility of forage consumed by sheep in Rio Grande do Sul.     

The effect of replacing rice straw with dry wormwood (Artemisia sp.) on intake,digestibility, nitrogen balance and ruminal fermentation characteristics in sheep

This study examined the effect of substituting dry wormwood (Artemisia sp.) for rice straw in sheep diets on intake and apparent digestibility in vivo, nitrogen (N) balance and ruminal fermentation characteristics. Four Corriedale×Polwarth sheep (51.7 ± 1.3 kg) were individually housed in metabolism cages and fed diets (ad. libitum) with a 70:30 forage to concentrate ratio (DM basis), in which the basal rice straw was substituted with 0 (Control), 30 (LW), 50 (MW) or 100 (HW) g/kg of dry wormwood. The experimental design was a 4×4 latin square design in which 10 days of dietary adaptation was followed by 6 days of total feces and urine collection in each period. Rumen fluid was collected from a stomach tube at −0.5, 0.5, 1, 2, 4, and 8 h after the morning feed on day 6 of each collection period and analyzed for volatile fatty acids (VFA). The intakes of dry matter (DM), organic matter intake (OM), crude protein (CP), ether extract (EE), neutral detergent fibre (NDF) and acid detergent fibre (ADF) were higher (P<0.05) in sheep fed diets containing wormwood, than those fed the Control diet. Compared to the Control diet, CP digestibility was higher (P<0.05) in sheep fed MW and N intake, retained N, EE digestibility, urinary purine derivatives and microbial N yield were higher (P<0.05) in sheep fed diets, containing wormwood. Rumen pH was unaffected by treatment. Rumen NH₃-N and VFA concentrations were similar across treatments except that most values for diets containing wormwood were higher (P<0.05) than those for the control diet within the first 2 h of feeding. The non-glucogenic acid ratio was also similar across Control, LW and MW treatments, but it was generally lower in MW versus the Control treatment. In conclusion, substituting wormwood for rice straw in the sheep diets increased feed intake, rumen fermentation, in vivo digestibility, N retention and microbial N yield, particularly at the medium and high levels of wormwood inclusion.     

Influence of undegraded intake protein on intake,digestion, serum hormones and metabolites,and nitrogen balance in sheep

In Exp. 1, 20 ewes of mixed breeding were fed grass hay : straw mixtures, assigned to one of four supplemental treatments and evaluated during six collection periods. Supplemental treatments were control (no supplement), and low, medium, and high levels (5.2%, 22.1%, and 41.3% of DM, respectively) of undegraded intake protein (UIP). Supplements were formulated to be similar in degraded intake protein (DIP; 21%). Digestibilities of DM, OM, and CP were increased (P < 0.10) with protein supplementation and in medium and high compared with low UIP supplemented ewes. Digestibility of CP also was increased (P < 0.10) in ewes on high compared with medium treatments. Serum insulin was not influenced (P > 0.10) by UIP treatment, except in collection period four. In contrast, serum glucose and growth hormone were not influenced (P > 0.10) by UIP treatment. In Exp. 2, four wether lambs fed the same treatments as in Exp. 1, were used in two 4 × 4 Latin squares trials. In trial 1 lambs received a grass hay diet (6.7% CP) and in trial 2 lambs were fed 40 : 60 blend (6.6% CP) of grass hay and spring wheat straw. In both trials, N intake, urinary N, N digestion, apparent N absorption, and N retention were increased (P < 0.10) with protein supplementation. In addition, in trial 1, urinary N, N digestion, and apparent N absorption were increased (P < 0.10) in medium and high compared with low UIP and also in high compared with medium UIP treatments. In trial 2 of Exp. 2, total feed intake (g/kg BW), digestibility of DM and OM, BW, and fecal N were increased (P < 0.10) with protein supplementation. Organic matter digestion, BW, N intake, and N retention were increased by medium and high compared with low UIP. Fecal N, BW, N intake, and N retention were increased (P < 0.10) in high compared with medium UIP. These data indicate that increasing levels of UIP supplementation increases DM, OM, and CP (N) digestibility, serum urea N concentration, and N retention in sheep fed low quality forage.     

Effects of feed intake on enteric methane emissions from sheep fed fresh white clover (Trifolium repens) and perennial ryegrass (Lolium perenne) forages

Published analyses of enteric methane (CH₄) emissions from sheep and cattle show an inverse relationship between feed intake and CH₄ yield (g CH₄/kg dry matter (DM) intake), which suggests opportunities for reducing CH₄ emissions from feed eaten and per unit of animal production. Most relationships between feed intake and CH₄ yield have been based on animals fed conserved feeds, especially silages and grains. Our research is a series of experiments with fresh white clover (Trifolium repens) and perennial ryegrass (Lolium perenne; ryegrass) forages fed to sheep at a range of feed intake levels. This study was comprised of four experiments where good quality freshly harvested white clover or ryegrass were fed to sheep over a three-fold range in DM intake, and CH₄ emissions were measured in respiration chambers for two consecutive days in each experiment. Measurements were made from 16 sheep in Experiment 1 (fed at 1.6 × metabolizable energy requirements for maintenance; ME_m), 28 sheep in Experiment 2 (at 0.8 and 2.0 × ME_m), eight sheep and two measurement periods in Experiment 3 (at 1.6 × ME_m), and 30 sheep in Experiment 4 (fed at 0.8, 1.2, 1.6, 2.0 and 2.5 × ME_m). Prior to each experiment, sheep had a 10 d acclimatization period to diets. Apparent digestibility was measured over 7 d from sheep in Experiments 1, 3 and 4, along with collection of rumen digesta for volatile fatty acid (VFA) determination. Although CH₄ yields differed when sheep were fed white clover or ryegrass at similar intakes, the differences were inconsistent and mean values similar across all experiments. This, and a similar structure of all experiments, enabled combined analysis of data from all four experiments using the restricted maximum likelihood (REML) procedure to estimate effects of feed intake level on digestibility, digestible nutrient intake, gas emissions, and VFA concentrations in the rumen. The REML analysis showed that when DM intake increased from 0.40 to 1.60 kg/d, the predicted responses were an increase in CH₄ production (g/d) of 187% (12.4–35.6 g/d; P<0.001), and a decline in CH₄ yield of 21% (25.6–20.2 g/kg DM intake; P<0.001). High feed intake levels were associated with increased molar proportions (mM of total VFA) of propionate from 0.17 to 0.21 (P=0.038). Single and multiple regressions were completed on the data from all experiments, with organic matter (OM) intake predicting 0.87 of the variation in CH₄ production, and molar proportion of propionate predicting 0.60 of the variation in CH₄ yield. Increasing feed intakes by 1 kg/d of DM reduced CH₄ yield by 4.5 g/kg DM intake. Plant chemical composition was weakly related to CH₄ yield. High intakes of fresh forages will lower CH₄ yield from fermentation, but effects of feed composition on CH₄ emissions were minor. The interaction between effects of feed intake and rumen function requires further investigation to understand relationships with CH₄ emissions.     

Intake and digestion by lambs of dwarf elephant grass (Pennisetum purpureum Schum. cv. Mott) hay or hay supplemented with urea and different levels of cracked corn grain

This study was carried out to evaluate intake, digestibility, ruminal fermentation, nitrogen (N) retention and ruminal microbial protein synthesis in lambs fed dwarf elephant grass (Pennisetum purpureum Schum. cv. Mott) hay or hay supplemented with urea and 0, 5, 10 or 15 g/kg of live weight (LW) of cracked corn grain. Ten lambs (mean LW of 28 ± 0.9 kg), housed in metabolic cages, were used in a double 5 × 5 Latin Square experiment. Except fibre intake and digestibility, which was higher, the intake and digestibility of the others feed components, as well as ruminal microbial protein synthesis and N retention were lower in non-supplemented lambs. Corn supplementation increased total dry matter (DM) (P<0.05), organic matter (OM), non-structural carbohydrate (NSC) and energy intake (P<0.01) but decreased total neutral detergent fibre (aNDFom) (P<0.01) intake, as well as OM and aNDFom intake from the hay (P<0.01). Apparent DM, OM and energy digestibility, as well as OM true digestibility (OMTD) increased (P<0.01), and aNDFom digestibility decreased linearly (P<0.01) as corn supplementation increased. Total N intake was not influenced but, apparent and true N digestibility, as well as urinary N excretion decreased (P<0.01), and ruminal microbial N entering the small intestine increased linearly (P<0.01) as corn supplementation increased. However, the efficiency of ruminal microbial protein synthesis was similar for all treatments. Mean ruminal pH values and ammonia N concentrations decreased linearly (P<0.01) with level of corn supplementation. Ammonia N and amino acid, as well as peptide concentrations in ruminal fluid were quadratically related (P<0.01) with the time after feeding. Corn supplementation had a linear additive effect on total dry matter and digestible energy intake, as well as on N retention, but a linear negative effect on hay intake and on fibre digestibility. However, decreased forage digestibility by animals was probably neither related to lower ruminal pH, which values were always higher than 7.0, nor related to ruminal sugar concentrations, which were similar for all treatments.     

Supplementation of isonitrogenous oil seed cakes in cactus (Opuntia ficus-indica)–tef straw (Eragrostis tef) based feeding of Tigray Highland sheep

The experiment was conducted at Maichew Agricultural Technical Vocational Education and Training College, Ethiopia. Twenty four male yearling Tigray Highland sheep with mean body weight (BW) of 21 ± 2.6 kg (mean ± S.D.) were used to investigate the effect of different protein sources on feed intake, nutrient digestibility, BW change and carcass parameters in a study comprising of 90 days feeding trial, followed by 7 days of digestibility trial and evaluation of carcass parameters. Six individually fed animals were used per treatment in a randomized complete block design. The treatments consisted of ad libitum feeding of tef (Eragrostis tef) straw plus 172 g dry matter (DM) of cactus (Opuntia ficus-indica) pear (T1, control) and supplementation with 145 g DM cotton seed cake (CSC) (T2), 195 g DM noug seed cake (NSC) (T3) or 149 g DM peanut cake (PNC) (T4) per head per day. The quantity of the supplements was set to supply 62.5 g crude protein (CP). Tef straw DM intake was depressed (P<0.01) as the result of NSC supplementation. Sheep supplemented with CSC and PNC had higher (P<0.001) total DM intake than the control and NSC supplemented ones. Supplementation with NSC and PNC also resulted in higher (P<0.01) apparent digestibility of DM and OM compared to the control treatment. Supplementation with CSC and PNC resulted in better daily BW gain (P<0.001), feed conversion efficiency (FCE) and dressed carcass weight (P<0.01) compared to the non-supplemented diet. Dressing percentage on slaughter weight base was higher (P<0.01) in supplemented sheep than in the non-supplemented ones. Supplementation with PNC also promoted higher (P<0.05) rib-eye muscle area than in the non-supplemented ones. It was concluded that supplementation with 145 g DM CSC and 149 g DM PNC resulted in better feed intake, BW gain and carcass traits in cactus–tef straw based feeding of sheep.     

Digestibility,nitrogen balance,and blood metabolites in llama (Lama glama) and alpaca (lama pacos) fed barley or barley alfalfa diets

To determine the effect of barley diets on digestibility, nitrogen balance, and blood metabolites, mature gelded llamas and alpacas (n = 8; 4 llamas, 36 ± 4 months, 90 ± 10.7 kg; 4 alpacas, 24–36 months, 50 ± 4 kg) were randomly fed 100% barley (B) and 20% alfalfa/80% barley (BA) hay. Animals were housed in metabolism crates and diets were fed for a 7 days adjustment period followed by a 5 days collection period. Feed, feed refusal, feces and urine were collected, dried and N content determined by combustion analysis. Blood samples were collected on day 12 at 30 min intervals over a 6 h period. Plasma was harvested and analyzed for electrolytes (Na, K, Cl, Ca, Ca²⁺, P, Mg), metabolites glucose, non-esterified fatty acids (NEFAs), urea N, creatinine, albumin, total protein (TPP), osmolality (Osm). Plasma glucose, urea N, albumin, osmolality, electrolyte and metabolite levels were similar between species, and were unaffected by diet. On a metabolic weight basis, only diet was significant for N intake, urinary and fecal N, and total N excreted. Dry matter intake was not significantly different; however, BA consumption was greater than B, (B) 1272 g N/day and (BA) 1636 g N/day for llamas, and for alpacas (B) 835 g N/day and (BA) 1034 g N/day, respectively. Nitrogen intake followed the same pattern, (B) 21.4 g N/day and (BA) 33.9 g N/day, respectively for llamas, and (B) 13.6 g N/day and (BA) 20.6 g N/day, respectively for alpacas (diet, P < 0.002). Diet affects were significant for urine N excretion (P < 0.02), (B) 11.2 g/day and (BA) 18.2 g/day for llamas, and (B) 6.8 and (BA) 10.8 g N/day for alpacas. Fecal N excretion was different for diet (P < 0.03), with fecal excreted N of 9.0 g N/day and 11.9 g N/day for B and BA in llamas, and 5.9 g N/day and 9.1 g N/day for B and BA respectively in for alpacas, respectively. Nitrogen retention, DM digestibility and N digestibility were unaffected by diet or species. However, the llamas in this study displayed an increase in nitrogen intake of 64.6% between the B and BA diets with a 381% increase in N retention. Alpacas increased their N intake by 57.4% when they consumed the BA forage, which only increased N retention by 22.2%. These species differences indicate that alpacas have a lower N requirement to meet metabolic needs than llamas, which are likely related to the smaller body size of the alpaca. When examining the biological value of N from the respective diets, alpacas and llamas had a value of 56.2% when consuming barley. The BA diet had a higher biological value of 65.0% in llamas compared to 57.4% in alpacas. Therefore, on the basis of this study, extrapolations between llamas and alpacas with respect to nitrogen requirement and balance are not valid.     

Effects of total nonstructural carbohydrates and nitrogen balance on voluntary intake of goats and digestibility of gamagrass hay harvested at sunrise and sunset

We evaluated differences in composition of Iuka gamagrass (Tripsacum dactyloides L.) hay harvested at 06:00 (AM harvest) or 18:00 h (PM harvest), and measured how protein supplementation and time of harvest interact to affect the voluntary intake, digestibility, and N balance of goats. Boer cross wethers (n = 28; 24 kg) were randomly assigned to be fed supplement (310 g/kg of crude protein (CP), fed at 110 g/kg of dry matter (DM) intake, 14 goats) or no supplement (14 goats). Within supplemented or not supplemented groups, goats were randomly assigned to a crossover design of AM harvest (seven goats) or PM harvest (seven goats), and housed individually in metabolism crates with free access to water and mineral blocks. They were fed twice daily, with supplement offered 30 min prior to the morning feedings. After a 7-d adaptation, voluntary intake (goats were offered 1100 g/kg of previous day's intake) was measured for 14 d, followed by a 4-d adjustment phase to equalize DM offered between periods, and finally a 5-d digestion and balance phase. After Period 1, goats were switched to their new hay harvest times, and the protocol was repeated. Compared to the AM harvest, the PM harvest had higher (P<0.03) proportions of total nonstructural carbohydrates (TNC, 70.8 g/kg DM versus 59.0 g/kg DM), monosaccharides (37.0 g/kg DM versus 28.6 g/kg DM), di- and polysaccharides (18.5 g/kg DM versus 15.4 g/kg DM) and less neutral detergent fiber (NDF, 700 g/kg versus 710 g/kg). Crude protein (79 g/kg DM) and starch (15.2 g/kg DM) were similar for the PM and AM harvest. Dry matter digestibility was higher (P<0.03) for the PM versus AM harvests (555 g/kg DM versus 531 g/kg DM) and for supplemented versus not supplemented (563 g/kg DM versus 522 g/kg DM). Voluntary gamagrass DM intake (550 g/d versus 548 g/d) and calculated total digestible DM intake (327 g/d versus 313 g/d) were similar for the PM and AM harvest. However, total digestible DM intake during the digestion and balance phase was higher (P<0.01) for the PM versus AM harvest (317 g/d versus 299 g/d). Time of harvest did not affect N intake, digestion, or calculated retention. Compared to no supplementation, the supplement improved (P<0.01) N digestion (6.1 g/d versus 3.7 g/d) and retention (2.2 g/d versus 1.1 g/d). The PM harvest increased DM digested, largely TNC and digestible DM intake by goats due to increased TNC and not because of a 2% increase in DM intake. Providing a protein supplement had very limited effects on intake and digestibility of gamagrass.     

Effects of sodium bicarbonate and yeast on nutrient intake,digestibility, and ruminal fermentation of light-weight lambs fed finishing diets

This study was conducted to determine the effects of adding yeast culture and sodium bicarbonate to the finishing diets for lambs on intake, digestibility, rumina1 parameters and nitrogen retention. Twenty Pelibuey male lambs, weighing an average of 23 kg, were assigned to one of four treatment groups according to a completely randomized design with a 2 × 2 factorial arrangement. Treatments were: (1) no additive (NA); (2) 0.12% yeast culture (YC); (3) 0.5% sodium bicarbonate (SB); and (4) 0.12% YC and 0.5% SB. During the 7-day collection period, SB increased DM intake (P < 0.05), while YC had no effect (P > 0.05) on intake. Intake of non-fibrous carbohydrates (NFC) was increased (P < 0.05) with SB in the ration, but not by supplementing YC (P > 0.05). The YC had no effect (P > 0.05) on dry matter (DM), neutral detergent fiber (NDF) or non-fibrous carbohydrates digestibility. A higher intake of NFC with the SB treatments was associated with a lower (P < 0.05) digestibility. SB increased excretion of NDF (P < 0.05), which reduced its digestibility (P < 0.05) by more than 9 percentage units. Lambs consuming diets with SB had 27% more N retained, in contrast with those fed the basal diet without additives. Rumen pH was greater than the minimum considered to cause acidosis (≤pH 5.5). The SB reduced (P < 0.05) percent molar acetate and increased (P < 0.05) percent molar propionate, which is in contrast to what has been normally observed with dairy cattle research. A lower acetate to propionate ratio with the SB rations may be a result of a lower digestibility and a higher intake of NDF, which may have increased the rate of passage of fiber particles through the gastrointestinal tract.     

Intake,digestion and selection of roughage with different staple lengths by sheep and goats

The diet selection, ingestive and digestive responses of goats and sheep offered a single forage, which was prepared with three staple lengths: long (L), medium (M) and short (S) (mean particle size (mm): 13.29, 7.26 and 0.69, respectively) were studied in three experiments. The sheep (Scottish Blackface wethers) increased their dry matter intake (sheep DMI: 60.1, 61.1 and 66.2 g DM/(kg W^0.75) per day for L, M and S) and reduced mean retention time (MRT) of the undigested residues (sheep MRT: 54.6, 52.9 and 45.9 h for L, M and S) and digestive efficiency (sheep DM digestibility: 0.524, 0.522 and 0.493 for L, M and S) with the reduction in forage particle size. The respective responses of goats (feral crosses) were not modified with forage staple length (goat DMI: 68.1, 65.9 and 67.3 g DM/(kg W^0.75) per day for L, M and S); (goat MRT: 38.7, 39.3 and 41.1 h for L, M and S); (goat DM digestibility: 0.495, 0.475 and 0.480 for L, M and S). However, both species had similar intakes of digestible dry matter (DDMI) on all staple lengths (mean DDMI: 32.0 and 32.6 g DDM/(kg W^0.75) per day for sheep and goats). On the longer staple lengths (L and M) goats masticated the fibre into smaller particles than did sheep and had (P<0.01) a greater proportion of small particles in their boli (mean: 0.45 and 0.30 for goats and sheep). The selection of components within the forage offered was different for the two species. Goats consumed forage of lower nitrogen (N) (P<0.01) and in vitro organic matter digestibility (OMD) (P<0.05) and higher neutral detergent fibre (NDF) (P<0.01) contents than sheep. This was associated with the residues from sheep having a coarser texture than those of goats. When the forages of different staple lengths were offered in pairs to the animals, there was no evidence for selection of forage types by either species. It would appear that the greater ability of goats to chew efficiently provides a reason for the different responses to staple length in intake, digestibility and MRT by the two species.     

Rumen enzyme profile and fermentation characteristics in sheep as affected by treatment with sodium lauryl sulfate as defaunating agent and presence of ciliate protozoa

The efficiency of sodium lauryl sulfate as a defaunating agent and effect of rumen protozoa on nutrient utilization, fermentation characteristics and enzyme profile were evaluated in adult sheep maintained on a mixed ration containing 65:35% Pala (Ziziphus numularia) leaf: concentrate. Twenty-one adult Malpura sheep divided into three equal groups (DF, RF and F) were either defaunated by oral administration of sodium lauryl sulfate at the rate of 8 g/100 kg body weight (DF), or defaunated and again refaunated (RF), or maintained faunated (F). Daily dry matter intake was similar in defaunated, refaunated and faunated sheep. However, digestibility of cell wall and cell wall contents (NDF, ADF and cellulose) were lower (P < 0.01) in defaunated than refaunated and faunated sheep. Irrespective of the presence or absence of rumen protozoa, daily intake of DCP and DE were similar in the three experimental groups. Even with similar DM, DCP and DE intake, N-retention, blood glucose level, ruminal concentration of total VFA and total-N were higher (P < 0.01), while rumen pH and NH₃-N concentration were lower (P < 0.01) in defaunated sheep. Ruminal activity of amylase, xylanase, protease and urease enzymes were not influenced by presence or absence of ciliate protozoa. However, carboxymethyl cellulase enzyme activity was lower (P < 0.01) in the rumen of defaunated sheep. The total and differential counts of rumen protozoa were similar in refaunated and faunated sheep indicating lack of residual toxic effect of sodium lauryl sulfate. It is concluded that absence of ciliate protozoa increased ruminal TVFA, total-N with lower NH₃-N concentration and fibre digestibility in sheep. Moreover, sodium lauryl sulfate was fully effective for complete removal of rumen ciliate protozoa and successfully defaunated the sheep.     

Nutritional characterization of Mucuna pruriens: 3. Effect of replacing soybean meal with Mucuna on intake,digestibility, N balance and microbial protein synthesis in sheep

Mucuna pruriens seeds have relatively high crude protein (CP) concentrations, but little is known about their potential to replace commonly used CP supplements in ruminant rations. The aim of this experiment was to determine effects of replacing soybean meal (SB) with Mucuna on the performance of lambs. Forty Rambouillet lambs (33.2 ± 5.73 kg) fed a basal diet of maize grain, cottonseed hulls and urea were randomly assigned to one of four supplements formulated by substituting 0 (SB), 330 (Lo), 670 (Med) or 1000 g/kg (Hi) of soybean meal with rolled Mucuna seeds. Lambs were housed individually in metabolic crates and allowed ad libitum access to isocaloric (metabolizable energy=11.7 MJ/kg dry matter, DM) and isonitrogenous (CP = 146 g/kg, DM) diets for 14 d of adaptation and 7 d of total fecal collection. Fecal egg counts and coccidian oocyst scores were determined on d 14. Dry matter intake (1.7 kg/d versus 1.5 kg/d; P<0.05), CP digestibility (774 g/kg versus 714 g/kg DM; P<0.05) and N retention (28.0 g/d versus 20.4 g/d; P<0.01) were higher and amylase-pretreated neutral detergent fiber digestibility (617 g/kg versus 686 g/kg DM) was lower (P<0.05) in sheep fed SB versus Mucuna diets. However, supplementary protein source did not affect rumen pH, blood urea N or glucose concentration, or fecal egg counts. Increasing the level of Mucuna supplementation increased (P<0.05) level and efficiency of microbial protein synthesis, ruminal fluid acidity, total volatile fatty acid concentration, decreased (P<0.05) coccidian oocyst scores, and tended (P<0.10) to increase N retention. Therefore, SB is a better supplement than Mucuna to support performance of lambs. Nevertheless, Mucuna seeds are a promising CP supplement for situations where cost or availability precludes use of SB in ruminant rations.     

In vivo and in situ digestibilities and nitrogen balance of Buddleia skutchii as a sole component and mixed with Pennisetum clandestinum in sheep diets

The objective of this work was to evaluate the intake (I) of all Buddleia skutchii foliage (BSF), collected from three different sites (places: A, B and C) in feeding sheep (phase 1), and in combination with Pennisetum clandestinum (Pc) (phase 2). Trials of feed intake, in vivo dry matter digestibility (IVDMD), and digestibilities of crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and nitrogen balance were carried out during phase 1. Diet was given to nine Creole male lambs of 23(±3) kg body weight (BW), located in individual metabolism crates. During phase 2, four treatments were evaluated (T1 = 100% Pc, T2 = 20% BSF + 80% Pc, T3 = 40% BSF + 60% Pc and T4 = 60% BSF + 40% Pc) in a 4 × 4 Latin square design, using four ruminal cannulated Creole male rams of 50 ± 2 kg BW and remained in individual metabolism crates. In vivo digestibility (DM, CP and gross energy (GE)) and kinetics of in situ disappearance of DM were evaluated. The results in phase 1 indicated that BSF from Site B had relatively higher CP (14.9%), ADF (50.6%) content and nitrogen retention (1.93 g d⁻¹). On the other hand, the lambs showed intake levels of 376.29 g d⁻¹ DM, 56.21 g d⁻¹ CP, 206.24 g d⁻¹ ADF and 1418.21 kcal gross energy (P > 0.05); and digestibilities of 54.23% DM, 47.17% CP and 39.31% NDF. Therefore, BSF from Site B was selected for the second phase of this work as the best result. We observed that the nutrition quality of the diets was higher as a result of increasing BSF concentration in the diet. When sheep were fed on 40% BSF–60% Pc, DM intake levels of 900.6 g d⁻¹, and DM, CP and GE digestibility of 70.0, 52.82 and 55.1%, respectively, were observed. There were not significant differences among diets, and in situ disappearance, K_d and K_p, but the diet with 60% of BSF presented higher ruminal digestibility (42.3%). The results allowed to validate the local knowledge on BSF as a promising forage species, and showed that BSF should be incorporated in a sheep production system.     

Clinical profile of sheep fed non-conventional feeds containing phenols and condensed tannins

A study was carried out to investigate the effects of feeding low quality non-conventional feeds (NCF) containing phenols and condensed tannins on the clinical profiles of sheep. Thirty-two Omani sheep were fed one of four diets with two base roughages, urea-treated palm frond (UTPF) and Rhodesgrass hay (RGH) and two concentrates, commercial concentrate (CC) and a by-products concentrate (BC) for 120 days. Haematological, serum biochemical and urine analyses were used to assess sheep health. Non-conventional feeds (urea-treated palm frond and by-products concentrate) contained higher levels of polyphenols and condensed tannins than conventional feeds (Rhodesgrass hay and commercial cubes). Feeds based on urea-treated palm frond had lower dry matter, crude protein, acid detergent fibre, neutral detergent fibre, gross energy (P < 0.001) and ash (P < 0.05) digestibility coefficients than those based on Rhodesgrass hay. Animals fed NCF had lower feed intake (P < 0.001) and lower body gain (P < 0.001) than those fed conventional ones. They also produced larger volumes of faeces (P < 0.01) which contained higher levels of nitrogen (P < 0.001) and had lower viscosity values of intestinal content (P < 0.001). Rumen liquor of NCF-fed animals had higher pH and lower ammonia–nitrogen levels (P < 0.01). Animals fed urea-treated palm frond plus by-products concentrate had lower lymphocyte (P < 0.01), monocyte (P < 0.05) and eosinophil (P < 0.05) counts by the end of the trial than those fed Rhodesgrass hay based diets. The urea-treated palm frond and by-products concentrate fed animals had lower blood urea nitrogen (BUN) levels (P < 0.05), higher (P < 0.01) alanine aminotransferase (ALT) and lower serum iron (P < 0.001) than those fed Rhodesgrass hay based diets. There was a trend of increasing blood, leukocytes and specific gravity in the urine of NCF-fed animals. This experiment implies that feeding low quality non-conventional feeds containing antinutritional factors for relatively long periods might produce subtle negative effects on the physiology and chemistry of the digestive system and blood parameters which might negatively affect sheep health and make them more susceptible to diseases.     

Effects of replacing corn with cactus pear (Opuntia ficus indica Mill) on the performance of Santa Inês lambs

The objective of this study was to evaluate the performance and nutrient digestibility of feedlot Santa Inês sheep fed with increasing levels (0, 25, 50, 75, 100% dry matter basis) of cactus pear (Opuntia ficus indica, Mill) as a replacement for corn. Forty-five male (non-castrated) Santa Inês sheep, averaging 27.50 ± 0.48 kg body weight (BW) at the beginning of the study, were used in this trial. A completely randomized block design with nine replicates per treatment was used. The intakes of DM, OM, CP, EE, TC, NFC, TDN and ME were quadratic, while the intakes of mineral matter (MM) and NDF increased linearly with increased levels of cactus pear in the diet. The voluntary intake of water decreased with increased levels of cactus pear in the diet. Increased levels of cactus pear in the diet increased the apparent digestibility of DM, OM, CP, NDF, and TC linearly, but did not influence the digestibility of EE or NFC. Daily weight gain (DWG) and feed efficiency decreased linearly with increased levels of cactus pear in the diet. The replacement of corn by cactus pear does not affect the conversion of the feed. Overall, increased levels of cactus pear in the diet of these sheep favours a high digestibility of nutrients, improves the quality of forage, reduces the voluntary intake of water, and thus represents an important source of fodder and water reserves for use in semiarid regions.     

Effect of feeding different levels of wilted cassava foliage (Manihot esculenta,Crantz) on the performance of growing goats

The effects of feeding different levels of wilted cassava foliage (Manihot esculenta, Crantz) on growth and diet digestibility were studied using local male growing goats with an average body weight of 14.5 kg. Thirty-two animals were randomly allocated to four groups of eight animals in a growth experiment, and four animals were assigned to a 4 × 4 Latin Square design to study digestibility. The four diets in both the growth and the digestibility studies were Gamba grass (Andropogon gayanus) as a sole diet offered ad libitum (control) or supplemented with wilted cassava foliage (WCF) at 20%, 30% and 40% of an expected daily DM intake of 3% of BW. Dry matter (DM) intake was significantly lower in the control group and increased with the level of WCF in the diet, while the DM intake of Gamba grass was not significantly changed. Total DM intake and DM intakes from Gamba grass were 472, 546, 584 and 616 g/d and 472, 457, 457 and 470 g/d for the control and treatments with 20%, 30% and 40% of WCF in the diet, respectively. The inclusion of WCF in the diet increased the apparent digestibility of DM, organic matter, N, Neutral detergent Fibre and Acid Detergent Fibre, and resulted in a higher N-retention. The average daily gains of animals fed diets with WCF were significantly higher than in the control group. The highest gain was recorded in goats with 40% of WCF in the diet (55.0 g/d) and lowest for the control (28.9 g/d). In conclusion, supplementing a basal diet of Gamba grass (Andropogon gayanus) with WCF improved DM intake, digestibility, N-retention and weight gain. The inclusion level of WCF in the diet can be up to 30%–40% of diet DM (21%–24% of total DM intake).     

Effects of fibre level and dietary mannanoligosaccharides on digestibility,caecal volatile fatty acids and performances of growing rabbits

The current experiment with 3 trials aimed to study the effect of two levels of dietary fibre – high fibre (HF; 323 g aNDFom/kg) and low fibre (LF; 248 g aNDFom/kg) – and the effect of mannanoligosaccharides (MOS) addition (1 g/kg) to the LF diet (LFM) on the performances and health status of growing rabbits, digestibility and caecal fermentative characteristics. In the growth trial 132 rabbits of both sexes were used (11 cages with 4 rabbits per treatment) from weaning (32 days of age) to slaughter (67 days of age). Rabbits fed HF diet showed a significantly higher weight gain and live weight at 67 days than rabbits fed LF diet (2032 g vs. 1935 g) (P<0.05). Feed and digestible energy intake increased with dietary fibre level (P<0.05). During the growing period rabbits fed HF diet had a feed intake 26% higher than those fed LF diet. Feed efficiency ratio was worse in HF animals (0.334 vs. 0.385; P<0.05). Addition of MOS to LF diet did not affect growth performance parameters (P>0.05). Mortality and morbidity rate were not affected by treatments. In the digestibility 24 rabbits from 46 to 51 days of age trial were used. The HF diet resulted in a significant (P<0.05) decrease in digestibility of dry matter, organic matter and protein while the aNDFom digestibility was not significantly different between diets (P>0.05). Supplementation with MOS had no effects on digestibility (P>0.05). In the 3rd trial the caecal traits were measured in 30 rabbits with 46 days of age that received the experimental diets in the previous 14 days. Caecal production of total volatile fatty acids (VFA), acetate and propionate were significantly higher (P>0.05) on rabbits fed HF diets than on rabbits fed LF diets. The total VFA concentration increased 64% (from 5.01 to 8.20 mmol/100 ml) and acetate increased 73% (from 3.73 to 6.44 mmol/100 ml). Butyrate production was not different between diets (P>0.05). Fibre level did not affect proportions of VFA and caecal contents and caecal weights. Addition of MOS to LF diet did not affect any caecal trait (P>0.05). It was concluded that the reduction of dietary fibre level increases feed digestibility but worsens rabbit growth performances. Supplementation of low fibre diet with 1 g MOS/kg is not enough to reduce its negative effects on growth performances.     

Effects of diets of differing fiber contents on digestibility,passage rate of digesta and heat production in lesser mouse deer (Tragulus javanicus)

The effects of different levels of dietary fiber on feed intake, digestibility, mean retention times of solute and particle and heat production were studied in twelve male lesser mouse deer (Tragulus javanicus). The animals were randomly assigned into four groups of three mouse deer each and fed on individual basis. Four diets, namely A, B, C and D were prepared in pellet forms. Each diet contained ～14% crude protein and ～18 kJ/g gross energy. The crude fiber contents of diet A, B, C and D were 4.2, 11.3, 16.8 and 22.5%, respectively. The results showed that the crude fiber intake of mouse deer was 1.4 ± 0.04, 3.8 ± 0.4, 5.8 ± 0.7 and 6.0 ± 0.6 g/kg W^0.75/d fed diet A, B, C and D, respectively. Mouse deer fed diet D had significantly lower DM intake than those fed lower levels of fiber. The digestibility values of DM decreased gradually with increasing levels of fiber in the diet. The mean retention times (MRTs) of particles (～1.5 mm) in the reticulorumen were in the range of (19.0–22.9 h), with the shortest time for mouse deer fed diet D. However mouse deer fed diet C and D showed significant shorter solute MRT in the reticulorumen (17.1–18.5 h) when compared to mouse deer fed lower fiber diets (21.4–21.9 h). The selectivity factor in the reticulorumen was in the range of 1.04–1.18, indicating the mouse deer to be a ‘moose-type’ ruminant. Fiber levels had no significant effect on water intake of mouse deer. Heat production tended to decrease with increasing levels of fiber (448.3–435.7 kJ/kg W^0.75/d) but differences among the mouse deer fed the four diets were not significant.     

Effect of elemental nano-selenium on feed digestibility,rumen fermentation,and purine derivatives in sheep

The objective of this experiment was to study the effect of elemental nano-selenium (NS) on feed digestibility, rumen fermentation, and urinary purine derivatives in sheep. Eight male ruminally cannulated sheep (42.5 ± 3.2 kg of body weight, BW) were used in a replicated 4×4 Latin square experiment in four 20 day periods. Depending on treatment designation, sheep were fed the basal diet supplemented with 0 (control), 0.3, 3 and 6 g of nano-Se/kg dry matter (DM). Ruminal pH (range of 6.68–6.80) and ammonia N concentration (range of 9.95–12.49 mg/100 mL) was decreased (P<0.01), and total VFA concentration (range of 73.63–77.72 mM) was increased linearly (P<0.01) and quadratically (P<0.01) with increasing nano-Se supplementation. The ratio of acetate to propionate was linearly (P<0.01) and quadratically (P<0.01) decreased due to the increasing of propionate concentration. In situ ruminal neutral detergent fiber (aNDF) degradation of Leymus chinensis and crude protein (CP) of soybean meal were linearly (P<0.01) and quadratically (P<0.01) improved by feeding nano-Se. Similarly, nutrients digestibility in the total tract and urinary excretion of purine derivatives were also quadratically (P<0.01) changed by increasing nano-Se supplementation. The present results indicated that nano-Se supplementation in basal diet improved rumen fermentation and feed utilization. Nano-Se could also stimulate rumen microbial activity, digestive microorganisms or enzyme activity. The optimum dose of nano-Se was about 3.0 g/kg dietary DM in sheep.     

Effects of urea and aqueous ammonia treatment on the composition and nutritive value of maize residues

Two trials were conducted to investigate changes in chemical composition and nutritive value of maize residues treated with urea and aqueous ammonia. In Experiment I, maize stalks, husks and cobs were chopped into pieces of approximately 1 cm length. Aqueous NH₃ (3%) and feed grade urea equivalent to 3% NH₃ were sprayed into 100 g duplicate samples on DM basis, thoroughly mixed, stored in plastic containers and kept for 3 week at ambient temperature (25–27 °C). Proximate composition and in vitro dry matter digestibility of test materials were determined. In Experiment II, 100 kg batches of the maize residues were chopped and treated as in Experiment I but stored in 205 l drums lined with black polythene sheet. Feed intake and nutrient digestibility of treated materials were evaluated with 18 mature WAD sheep averaging 19.8 kg BW. Treatment improved (P < 0.05) intake and digestion coefficients for N, DM, NDF, ADF and OM but there were no differences (P > 0.05) between aqueous NH₃ and urea treatments. Feed grade urea or the equivalent weight of fertilizer grade urea can be used to improve the nutritional value of maize residues for small ruminant feeding during off season periods.