Prediction of rabbit caecal fermentation characteristics from faeces by in vitro gas production technique: roughages

To find equations able to estimate the fermentation characteristics of the caecum from that of faeces, caecal content and faeces of 10 hybrid Hyla rabbits were used as inocula for an in vitro gas production trial. About 1 g of 12 roughages, 11 hays (ryegrass, alfalfa, sulla, oat, vetch, sulla-lolium, vetch-oat, sulla-oat, clover, ryegrass-clover, sulla-vetch-oat) and a wheat straw, was weighed, in triplicate per inoculum, in 120-ml flasks; 75 ml of anaerobic medium and 4 ml of reducing solution were added and the flasks were placed at 39 degrees C. Caecal content and faeces were diluted respectively 1:2 (CI) and 1:8 (FI) with anaerobic medium and were introduced into their respective flasks (10 ml). Gas production was recorded 20 times at 2-24 h intervals throughout fermentation (120 h). The fermentation characteristics (i.e. degraded organic matter, OMd; potential gas production, A; maximum fermentation rate, R(max); volatile fatty acid, VFA; ammonia, NH(3)) were studied by inocula and substrates. The two inocula did not differ in OMd but CI produced significantly higher gas (A, 213.1 vs. 199.4 ml/g, respectively, for CI and FI, p < 0.01) in less time (R(max), 3.08 vs. 2.24 ml/h, respectively, for CI and FI, p < 0.01). CI also produced higher levels of total VFA (57.86 vs. 46.70 mmol/g OM, respectively, for CI and FI, p < 0.01) and showed a higher branched chain proportion (0.023 vs. 0.018, respectively, for CI and FI, p < 0.01). For some parameters (as OMd pH and propionate) the equations for the estimation of caecal fermentation characteristics from that of faeces were accurate (R(2) > 0.8828) and reliable (CV < 10.78%) suggesting that faeces can be successfully used for the estimation of these parameters.     

Use of faeces as an alternative inoculum to caecal content to study in vitro feed digestibility in domesticated ostriches (Struthio camelus var. domesticus)

1. In order to find an alternative source of inoculum to caecal content for studying the in vitro feed digestibility in domesticated ostriches (Struthio camelus var. domesticus), caecal content and faeces of 4 male birds were used as inocula for an in vitro gas production trial. 2. About 1 g of each of 5 substrates (maize silage, CS; alfalfa hay, AH; barley, BG; soybean meal, SM; beet pulp, BP) was weighed, in quadruplicate per inoculum, in 120 ml flasks; 75 ml of anaerobic medium and 4 ml of reducing solution were added and flasks were kept at 39 degrees C. Caecal content and faeces were diluted respectively 1 : 2 (CI) and 1 : 4 (FI) with an anaerobic medium and were injected into the respective flasks (10 ml). 3. Gas production was recorded 22 times up to 120 h of incubation and fermentation characteristics (for instance, degraded organic matter, OMd; potential gas production, A; maximum fermentation rate, Rmax; time at which it is reached, Tmax; pH; volatile fatty acid, VFA; ammonia) were studied for each inoculum and substrate. 4. CI and FI showed significant differences in Tmax (16.37 vs 18.47 h, respectively), propionic (16.47 vs 12.07 mmoles/l) and butyric acid (6.50 vs 7.98 mmoles/l) and ammonia concentration (17.18 vs 19.95 mmoles/l). The substrates, according to their chemical composition, showed different fermentation characteristics. However, the regression equations able to estimate some fermentation characteristics of the caecum from those of faeces were statistically significant and showed R2-values ranging from 0.87 to 0.99. 5. The differences in fermentation pathways of the two inocula did not appear to influence the rate and extent of OM digestion. Faecal fermentation predicted rates and extent of OM digestion by caecal fermentation in ostriches; consequently, the faeces could be considered as an alternative to caecal content to study feed digestibility in the species, although there is a need to undertake further research.     

Effects of plant extracts from Stryphnodendron adstringens (mart.) coville,Lafoensia pacari a. st.-hil,copaifera spp., and Pterodon emarginatus Vogel on in vitro rumen fermentation

The effects of doses CTL (0 mg), 30, 300 and 3000 mg/L of extracts from Stryphnodendron adstringens (Mart.) Coville (SA), Lafoensia pacari A. St.-Hil (LP), Copaifera spp. (CO) and Pterodon emarginatus Vogel (PE) on ruminal fermentation were investigated in eight experiments conducted in randomized complete block designs. The in vitro system contained four fermentation vessels. Each treatment was allocated in one vessel in each run. Incubation was run four and five times with diets 50:50 and 10:90 (roughage to concentrate ratio) respectively. Incubation vessel was the experimental unit, and each incubation run was a block. All plant extracts negatively affected DM degradation at 3000 mg/L. In diet 50:50, SA-3000 increased the molar proportion of propionate (p < 0.05), yet it decreased the concentration of fermentation products (p < 0.05); LP-300 reduced ruminal ammonia nitrogen (NH₃-N; 98 vs. 120 mg/dl for LP-300 and average of CTL and LP-30, respectively) and isobutyrate (p < 0.05); CO-300 reduced (p < 0.05) NH₃-N (98 vs. 123 mg/dl for CO-300 and average of CTL and CO-30, respectively); and P. emarginatus had no positive effects on rumen fermentation (p > 0.05). In diet 10:90, SA-300 reduced (p < 0.001) NH₃-N and total volatile fatty acids (VFA); LP-30 increased (p < 0.05) total VFA (85 vs. 63 mM for LP-30 and CTL, respectively), molar proportions of acetate and propionate, and had lower C₂:C₃ than CTL (3.6 vs. 4.3, respectively); CO-300 decreased acetate and increased propionate, reducing C₂:C₃ (p < 0.001; 2.8 vs. 3.6 for CO-300 and average of other doses, respectively); PE-30 and PE-300 reduced NH₃-N by 14% and increased total VFA by 29% compared with CTL (p < 0.05). Further in vivo investigations may consider L. pacari (LP-30), Copaifera spp. (CO-300) oleoresin and P. emarginatus oleoresin (PE-30 and PE-300) in diets with high inclusion of concentrate.     

Influence of amount and frequency of protein supplementation to steers consuming low-quality,cool-season forage: intake,nutrient digestibility,and ruminal fermentation

This experiment evaluated the influence of protein supplementation frequency (SF) and amount offered on intake, nutrient digestibility, and ruminal fermentation by rumen-fistulated beef steers consuming low-quality [2.9% crude protein (CP); dry matter (DM) basis], cool-season forage. Seven Angus × Hereford steers (300 ± 27 kg) fitted with ruminal cannulas were randomly assigned to 1 of 7 treatments in an incomplete 7 × 4 Latin square. Treatments, in a 2 × 3 factorial design plus a non-supplemented control (CON), consisted of 2 levels of supplemental soybean meal, 100% (F) or 50% (H) of the estimated rumen-degradable protein requirement, provided daily (D), once every 5 d (5D), or once every 10 d (10D). Experimental periods were 30 d and dry matter intake (DMI) was measured from days 19 to 28. On days 21 (all supplements provided) and 30 (only daily supplements provided; day immediately prior to supplementation for 5D and 10D treatments) ruminal fluid was collected for ruminal pH, ammonia-N (NH₃), volatile fatty acids (VFA), and determination of ruminal fermentation variables. Forage and total DM, organic matter (OM), and nitrogen (N) intake increased with supplementation (P ≤ 0.04). However, a linear effect of SF × amount of supplement interaction was observed for forage and total DM, OM, and N intake (P ≤ 0.04), with each variable decreasing as SF decreased, but the decrease being greater with F vs. H. Apparent total tract DM, OM, and neutral detergent fiber digestibility was not affected by supplementation or amount of supplement provided (P ≥ 0.10). In contrast, N digestibility increased with supplementation and for F vs. H (P < 0.01). Digestibility of DM, OM, and N increased linearly as SF decreased (P ≤ 0.03). When all supplements were provided, ruminal NH₃, total VFA, and molar proportions of all individual VFA increased with supplementation (P ≤ 0.04), whereas acetate:propionate ratio decreased (P < 0.01). When only daily supplements were provided, none of the aforementioned fermentation parameters were affected (P ≥ 0.09). In summary, reducing the amount of supplemental CP provided to ruminants consuming low-quality forages, when supplementation intervals are >5 d, can be a management tool to maintain acceptable levels of DMI, nutrient digestibility, and ruminal fermentation while reducing supplementation cost.     

Molecular diversity of the equine caecal microbiota and its correlation to postprandial fermentation metabolites: A preliminary approach

Abstract

In this work we address the short-term postprandial dynamic changes in the equine caecal microbial composition and the microbial fermentation metabolites in the caecum. Samples were collected every half hour for 8.5 hours postfeeding from two horses on two consecutive days. The caecal content of volatile fatty acids (VFAs), lactate, and ammonia (NH₃N), as well as microbiota composition and pH were analyzed. Mixed Sangers sequences generated from universal polymerase chain reaction (PCR)-amplified 16S rRNA gene were used to analyze the microbiota composition. Three main phylogroups were identified and classified as Clostridium cluster XIVa, Clostridium cluster III, and lactic acid bacteria. Furthermore, we found that the composition of the caecal microbiota was closely associated with the VFA profile. Our main findings were that short-term microbial fluctuations occur in healthy hindgut fermenting horses as a response to feed intake.     

Evaluation of a single‐flow continuous culture fermenter system for determination of ruminal fermentation and enteric methane production

A 4‐unit, single‐flow continuous culture fermenter system was developed to assess in vitro nutrient digestibility, volatile fatty acid (VFA) concentration and daily enteric methane (CH₄) production of ruminant diets. The objective was to develop a closed‐vessel system that maintained protozoal populations and provided accurate predictions of total CH₄ production. A diet of 50% orchardgrass (Dactylis glomerata L.) and 50% alfalfa (Medicago sativa L.) was fed during 4, 10‐day periods (7‐day adaptation and 3‐day collection). Fermenters were fed 82 g of dry matter (DM)/day in four equal feedings. pH and temperature were taken every 2 min, and CH₄ concentration was measured every 10 min. Samples for DM and protozoal counts were taken daily, and daily effluent samples were collected for determination of DM, VFA and NH₃‐N concentrations. There was no effect (p > 0.17) of adaptation versus collection days on vessel and effluent DM, temperature or pH. Initial protozoal counts decreased (p < 0.01), but recovered to initial counts by the collection period. Total VFA, acetate, propionate and isobutyrate concentrations did not differ (p ≥ 0.13) among periods or days of the collection period. There was no difference (p ≥ 0.37) among days or periods in total daily CH₄ production and CH₄ production per g of OM, NDF, digestible OM or digestible NDF fed. Data collected throughout 4 experimental periods demonstrated that the system was able to reach a steady state in fermentation well within the 7‐day adaptation period and even typically variable data (i.e., CH₄ production) were stable within and across periods. While further research is needed to determine the relationship between this system and in vivo data, this continuous culture fermenter system provides a valid comparison of in vitro ruminal fermentation and enteric CH₄ production of ruminant diets that can then be further validated with in vivo studies.     

Reducing methane production by supplementation of Terminalia chebula RETZ. containing tannins and saponins

This study investigates the effects of Terminalia chebula Retz. meal supplementation on rumen fermentation and methane (CH₄) production by using an in vitro gas technique. The experimental design was a completely randomized design (CRD) and the dietary treatments were T. chebula supplementation at 0, 4, 8, 12, 16 and 20 mg with 0.5 g of roughage and concentrate ratio at 60:40. The results revealed that cumulative gas production (96 h of incubation) were higher (P < 0.01) with T. chebula supplementation at 12, 16 and 20 mg than other treatments. However, in vitro dry matter degradability (IVDMD) and in vitro organic matter digestibility (IVOMD) were not significantly different among treatments (P > 0.05). The NH₃‐N concentrations tended to quadratically increase with increasing levels of T. chebula in the diet. In addition, total volatile fatty acids (VFA) and propionate concentrations were increased (P < 0.01), while acetate concentration, acetate‐to‐propionate ratio, CH₄ production and protozoal populations were decreased (P < 0.01) when supplemented with T. chebula at 8, 12 and 16 mg, respectively. Based on this study, it could be concluded that supplementation of T. chebula at 12 mg could improve rumen fermentation by reducing CH₄ production and protozoa populations, thus improving in vitro gas production and VFA profiles.     

Plant Age and Growing Season Nutritional Content Relationships of Three Artemisia tridentata Subspecies

The effect of plant age on growing season chemical compositions and rumen fermentation characteristics was determined for three subspecies of big sagebrush: basin (Artemisia tridentata [Nutt.] subsp. tridentata), mountain (A. tridentata subsp. vaseyana [Rybd.] Beetle), and Wyoming (A. tridentata subsp. wyomingensis [Beetle and Young]). In vitro dry matter (IVDMD) and organic matter (IVOMD) disappearance, ammonia nitrogen (NH₃N), and volatile fatty acid (VFA) content were determined at the end of two fermentation periods (24 h and 48 h) by combining rumen inocula with age-classified vegetative samples from each sagebrush subspecies. An additional one-way analysis of variance was performed to investigate potential differences among subspecies in IVDMD, IVOMD, total VFA, and NH₃N following a 48-h fermentation period. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) components were also compared among sagebrush subspecies. Age class responses were variable across the spectrum of sagebrush subspecies and response variables. Where plant age effects were indicated, the small numeric differences probably have little biological or ecological significance. Mountain sagebrush was lower in IVOMD and total VFA concentrations (P < 0.0001) than basin and Wyoming. NH₃N concentration and CP were higher (P < 0.0001) in basin sagebrush than the other two subspecies, while Wyoming sagebrush was higher in NDF, ADF, and ADL than basin and mountain subspecies (P < 0.0001). NH₃N concentration for all three subspecies was lower than the minimum level (20 mg · 100 mL^?1) required for uninhibited rumen activity. Overall, this research questions the contention that older sagebrush plants offer less nutritional value than younger ones, at least for growing season conditions. The results also provide information that can be utilized in designing supplementation strategies for domestic animals on diets with characteristically high utilization of big sagebrush.     

Effects of supplementing low‐quality roughages with tree foliages on digestibility,nitrogen utilization and rumen characteristics in sheep: a meta‐analysis

Thirty‐six published studies containing 219 treatment means and 1069 sheep were included in the dataset for meta‐analysis to elucidate responses of foliage supplementation on digestibility, nitrogen balance and rumen parameters. Major predictive variables were percentages of foliages in diets (FL), crude protein (CP) in foliages (FCP), NDF in foliages (FNDF), NDF in basal forages (BNDF), CP in basal forages (BCP), CP in total diets (DCP) and foliage CP intake (FCPI). Organic matter digestibility increased linearly (p = 0.10) with increasing FL, but responded quadratically to DCP (p = 0.021) and BCP (p < 0.001), with maximal OM digestibility occurred at 14.6% of CP in diets (R² = 0.12). The digestibility of CP was affected by FL (p = 0.01), FCPI (p < 0.026), FCP (p < 0.001), FNDF (p < 0.001) and DCP (p < 0.032) positively and quadratically, and maximal response was at 14.1% DCP (p < 0.001), 51% FL (p < 0.001), 29% FCP (p < 0.001) and FCPI of 122 g/day (p < 0.001). The digestibility of NDF increased quadratically (p = 0.09) with increasing FL, peaking at 16% foliage levels, decreased quadratically (p = 0.001) with increasing FNDF and decreased linearly (p = 0.048) with increasing FCPI. Digestible OM and CP intakes were the highest at 37.2% and 42.1% FL, respectively. Fecal N excretion increased linearly with increasing FL (p < 0.001) and DCP (p < 0.001, R² = 0.66). However, FCPI (p = 0.082), FCP (p = 0.003) and BCP (p < 0.001) affected fecal N excretion positively and quadratically. Urinary N excretion increased linearly (p < 0.001) with increasing FL (R² = 0.45), FCPI (R² = 0.79), FCP (R² = 0.51), BCP (R² = 0.72) and DCP (R² = 0.77). Rumen NH₃ concentration was affected positively and quadratically (p = 0.023) by FL with a peak rumen NH₃ level of 160 mg/l at 17.3% FL. However, rumen NH₃ concentration (mg/l) increased linearly with increasing FCP (p = 0.001), FCPI (p = 0.01) and DCP (p < 0.001). In conclusion, catalytic foliage supplementation at low levels, preferably, at 16% may enhance nutrient utilization, while foliage levels up to 42% may result greater performance of sheep fed on low‐quality roughages.     

Effects of illite supplementation on in vitro and in vivo rumen fermentation,microbial population and methane emission of Hanwoo steers fed high concentrate diets

This study was conducted to evaluate the effects of feeding supplemental illite to Hanwoo steers on methane (CH₄) emission and rumen fermentation parameters. An in vitro ruminal fermentation technique was conducted using a commercial concentrate as substrate and illite was added at different concentrations as treatments: 0%, 0.5%, 1.0%, and 2.0% illite. Total volatile fatty acids (VFA) were different (P < 0.05) at 24 h of incubation where the highest total VFA was observed at 1.0% of illite. Conversely, lowest CH₄ production (P < 0.01) was found at 1.0% of illite. In the in vivo experiment, two diets were provided, without illite and with addition of 1% illite. An automated head chamber (GreenFeed) system was used to measure enteric CH₄ production. Cattle received illite supplemented feed increased (P < 0.05) total VFA concentrations in the rumen compared with those fed control. Feeding illite numerically decreased CH₄ production (g/day) and yield (g/kg dry matter intake). Rumen microbial population analysis indicated that the population of total bacteria, protozoa and methanogens were lower (P < 0.05) for illite compared with the control. Accordingly, overall results suggested that feeding a diet supplemented with 1% illite can have positive effects on feed fermentation in the rumen and enteric CH₄ mitigation in beef cattle.     

Performance and energy metabolism in restrictively fed weanling pigs are not affected by feeding either fermented cereals or their end‐products

To study the effects of feeding fermented cereals or just fermentation end‐products on performance and energy metabolism, 18 restrictedly fed groups of eight pigs each were assigned to one of three dietary treatments: (i) a liquid control diet (C) containing 40% of a mixture of barley and wheat; or (ii) a liquid diet (F) containing 40% fermented barley and wheat; or (iii) a liquid diet as C with the addition of some important fermentation end‐products (FP; organic acids and ethanol) in concentrations similar to those in the fermented F‐diet. Energy and nitrogen balances, heat production, and performance traits were measured during two consecutive periods (days 1–5 and days 6–14). There was a considerable increase in average dry matter intake that tended (p = 0.06) to be higher in the FP‐group than in the other groups. Apparent fecal digestibility of dry matter, ash, nitrogen and energy during period 2 were not affected (p > 0.1). Averaged over both periods, none of the energy metabolism parameters were affected by the diets (p > 0.1). However, there were diet × period interactions for metabolizable energy‐intake (p = 0.07), energy retention (p < 0.05), the respiratory quotient (RQ; p < 0.01) and activity‐related heat production (H_ACT, p = 0.05). Additionally, there were some differences between the diets in the average hourly patterns in RQ and H_ACT. In conclusion, restricted feeding of either 40% fermented cereals nor their fermentation end‐products affected performance and energy metabolism traits in weanling pigs. Nevertheless, lower postprandial activity‐related heat production by pigs given the fermented cereals suggest a stimulating effect of fermented cereals on short term satiety that was not seen in pigs given fermentation end‐products only.     

Effects of thermal energy on extrusion characteristics,digestibility and palatability of a dry pet food for cats

The influence of specific thermal energy (STE) applications on extruder preconditioner was evaluated in a dry food for cats. In the first study, six STE applications were tested with mass temperatures of 45°C, 55°C, 65°C, 75°C, 85°C and 95°C. The extrusion parameters, starch gelatinization and kibble formation were evaluated. Diets were given to cats to evaluate digestibility, faecal characteristics and palatability. In the second experiment, three treatments were compared: low STE—a preconditioner temperature of 45°C (_LSTE); high STE—a preconditioner temperature of 95°C (_HSTE); high STE (preconditioner temperature of 95°C) combined with an increase in the mass flow rate to obtain a motor amperage similar to that of the _LSTE (_HSTE_flow). Data were analysed by polynomial contrasts (Experiment 1) or Tukey's test (Experiment 2; p < 0.05). An increase in STE reduced motor amperage, mass pressure and specific mechanical energy (SME) implementation (p < 0.001) and increased total specific energy (TSE) and mass temperature (p < 0.01). The increase in STE induced greater kibble expansion and starch gelatinization (p < 0.001). No changes in apparent nutrient digestibility or faeces characteristics were observed (p > 0.05). Lower STE and starch gelatinization induced higher butyrate and total volatile fatty acid (VFA) contents in faeces (p < 0.01). Cats showed greatest preference for the formulation with the highest STE (p < 0.01). In the second experiment, when the motor amperage was increased in the _HSTE_flow treatment to a value similar to that of the _LSTE, the mass flow rate increased 40%, and the electric energy consumption remained unchanged (p < 0.001), with gains observed for efficiency and cost. In conclusion, STE application is important for sufficient TSE implementation, enhancing kibble expansion, starch gelatinization, cat preferences for food, extruder productivity and reducing SME application. Foods with lower starch gelatinization lead to increased VFA in faeces, with possible implications for gut health.     

In vitro fermentation characteristics of different carbohydrate sources in two dog breeds (German shepherd and Neapolitan mastiff)

Few studies have been published on the normal intestinal biota of canines unlike the wealth of information regarding livestock animal species. The in vitro gas production technique (IVGPT) including measurements of accumulating gas during fermentation and end‐product determinations allows obtaining a complete picture of microbial activity kinetics. The aim of this study was to study the in vitro fermentation characteristics of different carbohydrate sources using inocula from two dog breeds (German Shepherd and Neapolitan mastiff). Faeces sampled from rectum of two GS and NM adult dogs, fed the same dry food, were used as inocula. The samples, diluted and filtered, were incubated at 39 °C under anaerobic condition with nine substrates different for carbohydrate composition (rice, corn, potato, spelt, pure cellulose, beet pulp, wheat bran, inulin and fructo‐oligosaccharide). Gas production was recorded 17 times using a manual pressure transducer. After 48 h, the fermentation was stopped and fermenting liquor was analysed for pH and volatile fatty acids (VFA). Organic matter digestibility (OMD) was calculated as difference after burning the residuals. OMD, gas production and end‐products were significantly correlated with chemical composition of substrates, in particular carbohydrate fractions (total dietary fibre and starch), confirming the effectiveness of the IVGPT in evaluating dog feeds. Concerning the comparison between breeds significant differences (p < 0.01) were found for OMD, gas production, fermentation kinetic parameters and end‐products, suggesting a different pathway of fermentation and consequently, a different anaerobic population.     

Effect of oak (Quercus persica) acorn level on apparent digestibility,ruminal fermentation,nitrogen balance and urinary purine derivatives in pregnant goats

The aim of this experiment was to investigate the effect of dietary oak (Quercus persica) acorn (OA) level on dry matter intake (DMI), apparent nutrient digestibility, nitrogen (N) utilization, ruminal fermentation, protozoa population and urinary purine derivatives (PD) during the last 60 days of goat pregnancy. Twenty‐four multiparous pregnant goats (41.7 ± 2.3 kg BW) were assigned to one of three experimental diets consisted of control diet (C, without OA) and diets containing 20 (OA₂₀) or 40 g/100 g of OA (OA₄₀) on a DM basis in a completely randomized block design. Goats fed OA₄₀ had lower DMI (p < .01), DM (p < .01), OM (p < .01) and NDF (p < .05) digestibility, ruminal NH₃‐N concentration (p < .01), N intake (p < .01) and N retention (p < .01). Crude protein digestibility and ruminal acetate and total volatile fatty acid (VFA) concentration were lower in animals fed OA‐contained diets (p < .01), whereas ruminal propionate concentration was higher in goats fed the C diet (p < .01). Animals fed OA₄₀ had higher faecal N excretion and lower urinary N excretion (p < .01). Urinary PD was lower in goats fed diets containing OA in relation to those fed the C diet (p < .01). Total protozoa population decreased linearly with increasing OA level in the diet (p < .05). These results suggest that feeding OA, especially high level, has negative impacts on DMI, nutrient digestibility, VFA concentration, N retention and urinary PD excretion that may have adverse effects on metabolism and performance of pregnant goats.     

Nutritive value of sorghum silage for sheep

This study compared ensiled sorghum (ES) from two varieties (first and second cuts) with corn silage (CS) for chemical analysis, total-tract nutrient digestibility, ruminal variables and blood biochemistry metabolites in sheep. Five experimental silages representing first cut ES var. Pegah (PS1), second cut ES var. Pegah (PS2), first cut ES var. Speedfeed (SS1), second cut ES var. Speedfeed (SS2) and CS were assessed for chemical analysis, silage fermentation and anti-quality compounds. Diets consisted of lucerne hay, silage and a premix (at the ratio of 53.5:46:0.5 on a dry matter [DM] basis). Feed consumption, total-tract nutrient digestibility, microbial nitrogen supply (MNS), ruminal variables and blood biochemistry metabolites were determined in a Latin square design of five periods with five male sheep. Compared to sorghum, CS had lower (p < 0.01) concentrations of ash, water-soluble carbohydrates and crude protein, but higher starch, lignin (sa), non-structural carbohydrates and apparent nutrient digestibility. The measurements of pH, lactic acid, NH₃-N and volatile fatty acids (VFA) confirmed that all silages were well-preserved. The anti-quality compound levels in the silages were below the safe limits for ruminants. No differences were observed in feed consumption (p > 0.05) and total-tract digestibility of DM and nutrients (p > 0.05). Rumen pH, NH₃-N, VFA concentrations and acetate to propionate ratio showed no difference among treatments (p > 0.05). Sheep fed on sorghum silage showed a decrease (p < 0.01) in total protozoa, and particularly in the Entodiniae population. There were no differences in cellulolytic bacteria counts (p > 0.05) among treatments. Urinary N, MNS and blood biochemistry metabolites showed no difference among treatments (p > 0.05). Silages from both cuts of sorghum had comparable total-tract nutrient digestibility to CS, therefore, these varieties could be used as a more drought resilient silage source in the feeding of sheep.     

Influence of protein fermentation and carbohydrate source on in vitro methane production

Incubations were carried out with batch cultures of ruminal micro‐organisms from sheep to analyse the influence of the N source on in vitro CH₄ production. The two substrates were mixtures of maize starch and cellulose in proportions of 75:25 and 25:75 (STAR and CEL substrates, respectively), and the three nitrogen (N) sources were ammonia (NH₄Cl), casein (CA) and isolated soya bean protein (SP). Five isonitrogenous treatments were made by replacing non‐protein‐N (NPN) with CA or SP at levels of 0 (NPN), 50 (CA50 and SP50, respectively) and 100% (CA100 and SP100) of total N. All N treatments were applied at a rate of 35 mg of N/g of substrate organic matter and incubations lasted 16.5 h. With both proteins, N source × substrate interactions (p = 0.065 to 0.002) were detected for CH₄ production and CH₄/total VFA ratio. The increases in CH₄ production observed by replacing the NPN with protein‐N were higher (p < 0.05) for STAR than for CEL substrate, but the opposite was observed for the increases in volatile fatty acid (VFA) production. As a consequence, replacing the NPN by increased levels of CA or SP led to linear increases (p < 0.05) in CH₄/total VFA ratio with STAR, whereas CH₄/total VFA ratio tended (p < 0.10) to be decreased with CEL substrate. Increasing the amount of both proteins decreased linearly (p < 0.05) ammonia‐N concentrations, which may indicate an incorporation of amino acids and peptides into microbial protein without being first deaminated into ammonia‐N. In incubations with the tested N sources as the only substrate, the fermentation of 1 mg of CA or SP produced 1.24 and 0.60 μmol of CH₄ respectively. The results indicate the generation of CH₄ from protein fermentation, and that the response of CH₄ production to protein‐N supply may differ with the basal substrate.     

Dietary dragon fruit (Hylocereus undatus) peel powder improved in vitro rumen fermentation and gas production kinetics

Plant phytophenols especially condensed tannins (CT) and saponins (SP) have been demonstrated to impact on rumen fermentation. Dragon fruit (Hylocereus undatus) peel powder (DFPP) contains both CT and SP. The current study aimed to investigate the influence of DFPP and varying levels of concentrate and roughage ratios on gas production kinetics, nutrient degradability, and methane production “using in vitro gas production technique.” The dietary treatments were arranged according to a 3?×?5 Factorial arrangement in a completely randomized design. The two experimental factors consisted of the roughage to concentrate (R:C) ratio (100:0, 70:30, and 30:70) and the levels of DFPP supplementation (0, 1, 2, 3, and 4% of the substrate) on DM basis. The results revealed that the R:C ratio at 30:70 had the highest cumulative gas production when compared to other ratios (P?<?0.01). The in vitro true dry matter degradability at 12 and 24 h was affected by R:C ratio (P?<?0.01). Furthermore, volatile fatty acids (VFA) and propionate (C3) were significantly increased by the levels of DFPP, while acetate (C2) and C2:C3 ratios were decreased (P?<?0.05). The rumen protozoal population was significantly decreased by DFPP supplementation (P?<?0.05). Rumen methane production was significantly impacted by R:C ratios and decreased when the level of DFPP increased (P?<?0.01), while NH₃-N and ruminal pH were not influenced by the DFPP supplement. It could be summarized that supplementation of DFPP resulted in improved rumen fermentation kinetics and could be used as a dietary source to mitigate rumen methane production, hence reducing greenhouse gas production.

     

ORIGINAL ARTICLE: Effects of ambient temperature and soybean meal supplementation on intake and digestion of two sheep breeds differing in mature size

The aim of this study was to compare the intake and digestive physiology of mature ewes of two breeds ? Ile‐de‐France (mature weight: 75–80 kg) and Churra‐da‐Terra‐Quente (CTQ; mature weight: 45–50 kg) ? and evaluate the effects of ambient temperature and protein supplementation in the comparison. The temperature (25 °C vs. 11 °C) and soybean meal supplementation (150 g/kg of ingested hay on dry matter basis vs. unsupplemented control) were evaluated in 48 adult ewes of two breeds fed hay ad libitum and at a restricted level of intake. The intake, digestibility, rumen pH and NH₃–N, rumen outflow rates, faeces particle size and thyroid hormones levels were measured. These hormones can be related with gastrointestinal motility, thus explaining rumen outflow rate patterns. Dry matter intake per kg of body weight was higher in CTQ ewes (p < 0.05). This breed also exhibited lower organic matter and neutral detergent fibre digestibility (p < 0.001) and higher solid (p < 0.001) and liquid (p < 0.01) rumen outflow rates irrespective of intake level, supplementation or temperature. Rumen pH remained above 6.6 in all treatments. NH₃–N rumen content was similar (p > 0.05) when breeds were fed only hay. There was no breed effect (p > 0.05) on faeces particle size. Triiodothyronine was not affected (p > 0.05) by breed and thyroxine was higher (p < 0.10) in the CTQ breed but only at the lower temperatures (breed × temperature, p < 0.05). Ile‐de‐France sheep showed a lack of adaptation to lower temperatures. This study suggests that the native CTQ breed fulfils its metabolic needs by having a higher intake and inherits faster flow through the gastrointestinal tract, as a result, its digestive ability is diminished.     

Effects of defaunation and dietary coconut oil distillate on fermentation,digesta kinetics and methane production of Brahman heifers

A 2 × 2 factorial experiment was conducted to assess the effects of presence or absence of rumen protozoa and of dietary coconut oil distillate (COD) supplementation on rumen fermentation characteristics, digesta kinetics and methane production in Brahman heifers. Twelve Brahman heifers were selected to defaunate, with 6 being subsequently refaunated. After defaunation and refaunation, heifers were randomly allocated to COD supplement or no supplement treatments while fed an oaten chaff‐based diet. Methane production (MP; 94.17 v 104.72 g CH₄/d) and methane yield [MY; 19.45 v 21.64 g CH₄/kg dry matter intake (DMI)] were reduced in defaunated heifers compared with refaunated heifers when measured at 5 weeks after refaunation treatment (p < 0.01). Supplement of COD similarly reduced MP and MY (89.36 v 109.53 g/d and 18.46 v 22.63 g/kg DMI, respectively; p < 0.01), and there were no significant interactions of defaunation and COD effects on rumen fermentation or methane emissions. Concentration of total volatile fatty acid (VFA) and molar proportions of acetate, propionate and butyrate was not affected by defaunation or by COD. Microbial crude protein (MCP; g/d) outflow was increased by defaunation (p < 0.01) in the absence of COD but was unaffected by defaunation in COD‐supplemented heifers. There was a tendency towards a greater average daily gain (ADG) in defaunated heifers (p = 0.09), but COD did not increase ADG (p > 0.05). The results confirmed that defaunation and COD independently reduced enteric MP even though the reduced emissions were achieved without altering rumen fermentation VFA levels or gut digesta kinetics.     

Yeast mixture of liquid beer and cassava pulp with rice straw for the growth of dairy heifers

This study was conducted to determine the effects of mixtures of liquid brewer’s yeast (LBY) and cassava pulp (CVP) with rice straw (RS) on feed intake, digestibility, rumen fermentation, and growth of dairy heifers. Sixteen Holstein crossbred heifers (13.8?±?1.6 months old, 210?±?23 kg body weight (BW)) were randomly allocated to four feeding treatments with four replications, which were 0:0:100 (RS), 0:70:30 (0%LBY), 20:50:30 (20%LBY), and 50:20:30 (50%LBY), respectively, for LBY/CVP/RS on a fresh matter basis. The heifers were offered conventional concentrate at 1.5% initial body weight daily and fed the treatment diets ad libitum. Average daily gain and feed intake were not significantly different among the treatments. The heifers fed 50%LBY had the highest crude protein (CP) intake and DM, OM, and CP digestibility (P?<?0.05). The ruminal pH did not differ significantly among treatments, while NH₃-N was the highest (P?<?0.05) in 50%LBY. Total volatile fatty acid (VFA) concentrations and the molar proportion of each VFA were not significantly different among the treatments. Blood urea nitrogen concentrations of 50%LBY were the highest among the treatments (P?<?0.05). The results indicated that 50%LBY improved CP digestibility.