Microbial Crude Protein Synthesis Research Articles

Hydrogen-rich water 400ppb as a potential strategy for improving ruminant nutrition and mitigating methane emissions.

The objective of this study was to evaluate the effects of different concentrations of hydrogen-rich water (HRW) on in vitro rumen fermentation characteristics and the dynamics of bacterial communities. The experiment included four treatment groups: a control (CON) and hydrogen-rich water (HRW) at 200, 400, and 800 ppb. Each group was analyzed at 12-hour (h) and 48-hour (h) time points with five replicates, totaling 40 samples. The experimental results highlighted the HRW800ppb group as the top production in terms of gas production and CH4 content. In contrast, the HRW200ppb group exhibited significantly lower methane levels at both 12h and 48h (P < 0.05). Regarding rumen fermentation, the HRW400ppb group significantly increased the levels of ammonia nitrogen (NH3-N) and microbial crude protein (MCP) at 12h fermentation, but reduced the dry matter degradation rate (P < 0.05). After 48h, the HRW400ppb group had highest MCP content (P < 0.05), but no significant differences in NH3-N and dry matter degradation rate compared with the CON group (P > 0.05). Although HRW did not significantly benefit the synthesis of total volatile fatty acids (TVFA) and individual VFA, the HRW800ppb group significantly increased the ratio of acetate to propionate (P < 0.05). Based on CH4 emissions and MCP synthesis, we selected the HRW400ppb group for subsequent bacterial community analysis. Bacterial community analysis showed that at 12h, compared with the CON group, the Bacterial community analysis revealed that the HRW400ppb group had significant increases in the Simpson index, Firmicutes, Streptococcus, Schwartzia, Prevotellaceae_YAB2003_group, and Oribacterium, and decreases in Prevotella, Ruminobacter, Succinivibrio, unclassified_Succinivibrionaceae, and Prevotellaceae_UCG-003 (P < 0.05). At 48h, the Prevotellaceae_YAB2003_group and Oribacterium abundances continued to rise significantly, while Rikenellaceae_RC9_gut_group and Succiniclasticum abundances fell in the HRW400ppb group (P < 0.05). Correlation analysis indicated a negative link between CH4 and Streptococcus, and a positive correlation between the abundance of Rikenellaceae_RC9_gut_group and CH4. Collectively, these results indicate that HRW can modulate rumen fermentation and microbial community structure to reduce methane emissions without significantly affecting VFA synthesis, highlighting its potential as drinking water for enhancing ruminant nutrition and mitigating the environmental impact of livestock farming.

Predicting Microbial Protein Synthesis in Cattle: Evaluation of Extant Equations and Steps Needed to Improve Accuracy and Precision of Future Equations.

Predictions of microbial crude protein (MCP) synthesis for beef cattle generally rely on empirical regression equations, with intakes of energy and protein as key variables. Using a database from published literature, we developed new equations based on the intake of organic matter (OM) and intakes or concentrations of crude protein (CP) and neutral detergent fiber (NDF). We compared these new equations to several extant equations based on intakes of total digestible nutrients (TDN) and CP. Regression fit statistics were evaluated using both resampling and sampling from a simulated multivariate normal population. Newly developed equations yielded similar fit statistics to extant equations, but the root mean square error of prediction averaged 155 g (28.7% of the mean MCP of 540.7 g/d) across all equations, indicating considerable variation in predictions. A simple approach of calculating MCP as 10% of the TDN intake yielded MCP estimates and fit statistics that were similar to more complicated equations. Adding a classification code to account for unique dietary characteristics did not have significant effects. Because MCP synthesis is measured indirectly, most often using surgically altered animals, literature estimates are relatively few and highly variable. A random sample of individual studies from our literature database indicated a standard deviation for MCP synthesis that averaged 19.1% of the observed mean, likely contributing to imprecision in the MCP predictions. Research to develop additional MCP estimates across various diets and production situations is needed, with a focus on developing consistent and reliable methodologies for MCP measurements. The use of new meta-omics tools might improve the accuracy and precision of MCP predictions, but further research will be needed to assess the utility of such tools.

Nutritional, ruminal, and metabolic parameters of beef bulls fed high-energy diets as a function of dietary addition of a magnesium oxide blend associated or not with monensin

This study aimed to evaluate the impact of a magnesium oxide blend (MG) and monensin (MON) on the nutritional, ruminal, and metabolic parameters of finishing bulls fed high grain diet. Six ruminally cannulated bulls (542 ± 33.6 kg) were used in a 6 × 6 Latin square design with treatments arranged as a 2 × 3 factorial, with 6 periods of 23 days. The MG was included at 0, 2.5, or 5.0 g/kg of dry matter (DM) - MG0, MG2.5, and MG5.0, respectively, without or with MON (30 mg/kg of DM). During each experimental period, days 1–10 were designated for dietary additive adaptation. Days 11–20 (feeding period), were used to assess DM and nutrient intakes, digestibility, ruminal pH, volatile fatty acids (VFA) profile, and blood parameters. Days 21–23 (corn challenge period), included supplementing all treatments with 2 kg/day of ground corn, replacing 2 kg/day of forage, to observe responses in ruminal pH and DM intake (DMI) in the presence of increased fermentable carbohydrates in the rumen. The ruminal pH increased linearly (P = 0.01) with the MG level during the feeding period. In the corn challenge, bulls fed diets without MON and MG5.0, as well as those fed MON and MG2.5 or MG5.0 showed a marked increase in rumen pH value during the first day. In the feeding period, the DMI was greater (quadratic: P = 0.05) for MG2.5 compared to other tested doses. The DM and nutrient intakes were greater (quadratic: P ≤ 0.05) for the MG2.5 group. Bulls fed MON diets had 0.5 kg lower DM and nutrient intakes than those without MON (P ≤ 0.05). The ruminal and intestinal digestibility of diet compounds did not differ among treatments (P ≥ 0.08). The DM and organic matter (OM) apparent total-tract digestibility tended to be (quadratic: P = 0.06) and were greater (quadratic: P = 0.05) for the MG2.5 group. The microbial crude protein synthesis (MCP) was greater for bulls fed the MG2.5 diet (quadratic: P = 0.03). Bulls fed diets without MON had a lower valeric acid (MON × Time: P = 0.03) and those fed diets without MG had a lower iso-valeric acid (MG × Time: P = 0.03) molar proportion 12 hours post-feeding than 1 hour pre-feeding. Glucose levels increased linearly with MG doses (P < 0.001). In summary, a dosage of 5.0 g/kg of DM of MG promotes a superior response in ruminal pH, whereas beneficial effects on digestive parameters are achieved with 2.5 g/kg of DM. Furthermore, MON and MG showed no significant associative effects.

Optimizing dietary rumen-degradable starch to rumen-degradable protein ratio improves lactation performance and nitrogen utilization efficiency in mid-lactating Holstein dairy cows.

The dietary rumen-degradable starch (RDS) to rumen-degradable protein (RDP) ratio, denoted as the RDS-to-RDP ratio (SPR), has been proven to enhance in vitro rumen fermentation. However, the effects of dietary SPR in vivo remain largely unexplored. This study was conducted to investigate the effect of dietary SPR on lactation performance, nutrient digestibility, rumen fermentation patterns, blood indicators, and nitrogen (N) partitioning in mid-lactating Holstein cows. Seventy-two Holstein dairy cows were randomly assigned to three groups (24 head/group), balanced for (mean ± standard deviation) days in milk (116 ± 21.5), parity (2.1 ± 0.8), milk production (42 ± 2.1 kg/d), and body weight (705 ± 52.5 kg). The cows were fed diets with low (2.1, control), medium (2.3), or high (2.5) SPR, formulated to be isoenergetic, isonitrogenous, and iso-starch. The study consisted of a one-week adaptation phase followed by an eight-week experimental period. The results indicated that the high SPR group had a lower dry matter intake compared to the other groups (p < 0.05). A quadratic increase in milk yield and feed efficiency was observed with increasing dietary SPR (p < 0.05), peaking in the medium SPR group. The medium SPR group exhibited a lower milk somatic cell count and a higher blood total antioxidant capacity compared to other groups (p < 0.05). With increasing dietary SPR, there was a quadratic improvement (p < 0.05) in the total tract apparent digestibility of crude protein, ether extract, starch, neutral detergent fiber, and acid detergent fiber. Although no treatment effect was observed in rumen pH, the rumen total volatile fatty acids concentration and microbial crude protein synthesis increased quadratically (p < 0.05) as dietary SPR increased. The molar proportion of propionate linearly increased (p = 0.01), while branched-chain volatile fatty acids linearly decreased (p = 0.01) with increasing dietary SPR. The low SPR group (control) exhibited higher concentration of milk urea N, rumen ammonia N, and blood urea N than other groups (p < 0.05). Despite a linear decrease (p < 0.05) in the proportion of urinary N to N intake, increasing dietary SPR led to a quadratic increase (p = 0.01) in N utilization efficiency and a quadratic decrease (p < 0.05) in the proportion of fecal N to N intake. In conclusion, optimizing dietary SPR has the potential to enhance lactation performance and N utilization efficiency. Based on our findings, a medium dietary SPR (with SPR = 2.3) is recommended for mid-lactating Holstein dairy cows. Nevertheless, further research on rumen microbial composition and metabolites is warranted to elucidate the underlying mechanisms of the observed effects.

Comparison of the effects of rumen-protected and unprotected L-leucine on fermentation parameters, bacterial composition, and amino acids metabolism in in vitro rumen batch cultures

This study was conducted to compare the effects of rumen-protected (RP-Leu) and unprotected L-leucine (RU-Leu) on the fermentation parameters, bacterial composition, and amino acid metabolism in vitro rumen batch incubation. The 5.00 g RP-Leu or RU-Leu products were incubated in situ in the rumen of four beef cattle (Bos taurus) and removed after 0, 2, 4, 6, 12, 16, and 24 h to determine the rumen protection rate. In in vitro incubation, both RP-Leu and RU-Leu were supplemented 1.5 mmol/bottle (L-leucine HCl), and incubated after 0, 2, 4, 6, 8, 12, and 16 h to measure gas production (GP), nutrient degradability, fermentation parameters, bacterial composition, and amino acids metabolism. Results from both in vitro and in situ experiments confirmed that the rumen protection rate was greater (p &amp;lt; 0.01) in RP-Leu than in RU-Leu, whereas the latter was slow (p &amp;lt; 0.05) degraded within incubation 8 h. Free leucine from RP-Leu and RU-Leu reached a peak at incubation 6 h (p &amp;lt; 0.01). RU-Leu supplementation increased (p &amp;lt; 0.05) gas production, microbial crude protein, branched-chain AAs, propionate and branched-chain VFAs concentrations, and Shannon and Sobs index in comparison to the control and RP-Leu supplementation. RU-Leu and RP-Leu supplementation decreased (p &amp;lt; 0.05) the relative abundance of Bacteroidota, which Firmicutes increased (p &amp;lt; 0.05). Correlation analysis indicated that there are 5 bacteria at the genus level that may be positively correlated with MCP and propionate (p &amp;lt; 0.05). Based on the result, we found that RP-Leu was more stable than RU-Leu in rumen fluid, but RU-Leu also does not exhibit rapid degradation by ruminal microbes for a short time. The RU-Leu was more beneficial in terms of regulating rumen fermentation pattern, microbial crude protein synthesis, and branched-chain VFAs production than RP-Leu in vitro rumen conditions.

Effect of substituting maize silage with fresh or ensiled sugar beets on nutrient digestibility, rumen fermentation and microbial synthesis, and enteric methane emission in dairy cows

This study aimed to 1) examine nutrient digestibility, rumen fermentation and microbial synthesis, and enteric methane emission when feeding diets high in sugar content provided as freshly stored or ensiled sugar beets to dairy cows, and 2) to evaluate the methane mitigation potential of ensiled sugar beets with different nutrient composition (sugar vs. alcohol) by use of an additive during ensiling. Four rumen, duodenal and ileal fistulated Danish Holstein dairy cows were used in a 4 × 4 Latin square design with 21-d periods. Maize silage was included in the control diet (CON) and was partially replaced in the experimental diets with either freshly stored sugar beets (SBF), ensiled beets with ensiling additive (SBE+), or ensiled beets without ensiling additive (SBE−) at 196 g/kg dietary dry matter (DM) content. Cows adapted to the diets for 11 d, after which rumen liquid and digesta were collected over 5 d, and gas exchange was measured in respiration chambers over the next 5 d. Dry matter intake (DMI), daily methane production, and methane per kg organic matter (OM) intake, rumen digested OM, and energy-corrected milk (ECM) yield were unaffected by diet. Methane per kg DMI (tendency) and per kg OM intake was lower for SBE– compared to SBF. Nutrient digestibility of DM, OM, starch, and neutral detergent fibre in different sections of the digestive tract were unaffected by diet. Molar proportion of acetate in rumen liquid decreased for ensiled sugar beet diets relative to CON, while molar proportions of propionate and acetate-to-propionate ratio remained unaffected. Molar proportion of butyrate was higher for SBE+ than CON. Microbial crude protein synthesis and microbial efficiency were unaffected by diet. Milk yield and ECM yield (tendency) were lower for SBE+ than CON. In conclusion, freshly stored sugar beets and sugar beets ensiled with or without additive, can replace maize silage in dairy cattle rations without adverse effects on DMI, rumen fermentation, and nutrient digestibility, and without altering most expressions of methane emissions, but methane per kg of OM intake was lower for beets ensiled without additive compared to freshly stored beets. The ECM yield, however, tends to be lowered for ensiled beets with additive.

134 Effect of Rumen Degradable Protein Intake on Performance, Carcass Quality, and Methane Emissions of Yearling Finishing Steers

Abstract The performance, economic, and environmental consequences of feeding rumen degradable protein (RDP) levels above and below calculated maximum energy-dependent microbial crude protein (MCP) synthesis potential are poorly understood. Yearling steers (n = 54; initial BW = 484.1 ± 26.03 kg) were assigned to one of two pens that each contained an automated head chamber system (GreenFeed; C-Lock Inc., Rapid City, SD) for individual measurement of enteric methane (CH4) emissions. Each steer was assigned to an individual feed bunk (Calan Gate; American Calan, Northwood, NH) and randomly assigned to one of three dietary treatments: low RDP intake (LRDPI; n = 8), neutral RDP intake (NRDPI; n = 8), or high RDP intake (HRDPI; n = 8) in a completely randomized design. Steers were transitioned to treatment diets utilizing a two-ration blend system for 20-day followed by an 80-day finishing period. Diets were formulated to provide cattle with similar metabolizable protein (MP) and net energy for gain (NEg) but different RDP supply. Diets were formulated to provide approximately 87% (LRDPI), 100% (NRDPI), or 113% (HRDPI) of calculated RDP requirements to maximize energy-allowable MCP-yield. Paired-day, unshrunk BW was collected on d 0, 50, and 80, and cattle were transported to a commercial abattoir for carcass data collection. Statistical analyses were conducted using Analysis of Variance in JMP Pro6.0 using the Fit Model procedure. Least-squares means differences were considered statistically significant if P &amp;lt; 0.05 and considered a tendency toward significant if 0.05 ≤ P &amp;lt; 0.15. Treatment rations provided approximately 94% (LRDPI), 106% (NRDPI), and 118% (HRDPI) of the RDP required to maximize energy-allowable MCP yield, respectively. Daily DMI was similar (P &amp;gt; 0.15) for HRDPI and NRDPI cattle, but LRDPI cattle tended (P = 0.06) to have less DMI than NRDPI cattle. Dietary treatment did not affect (P ≥ 0.32) ADG, feed conversion efficiency, ribeye area, marbling score or carcass yield grade. Yet, LRDPI cattle had lighter hot carcass weight (P &amp;lt; 0.05) and less subcutaneous fat thickness (P &amp;lt; 0.05) than NRDPI cattle, whereas HRDPI cattle were not different (P ≥ 0.15) from the other treatments. On average, LRDPI cattle tended to emit 7.0% more daily CH4 (g×d-1; P = 0.05) than both NRDPI and HRDPI. Moreover, the LRDPI treatment elicited a 14.7% and 18.1% increase in CH4-yield (g CH4×kg DMI-1; P &amp;lt; 0.01) and emission intensity (g CH4×kg ADG-1; P &amp;lt; 0.05) compared with the other treatments, respectively. These data indicate that limiting MCP-yield by restricting RDP intake may reduce subcutaneous fat thickness and carcass weight while increasing enteric CH4 emissions. These results reiterate the importance of meeting RDP requirements and suggest no performance or methane emission benefits of overfeeding RDP.

Effects of taurine on rumen fermentation, nutrient digestion, rumen bacterial community and metabolomics and nitrogen metabolism in beef steers.

The objectives of this study were to investigate the effects of taurine on rumen fermentation, rumen bacterial community and metabolomics, nitrogen metabolism and plasma biochemical parameters in beef steers. Six castrated Simmental steers (liveweight 402 ± 34 kg) and three levels of taurine (0, 20, 40 g d-1 ) were assigned in a replicated 3 × 3 Latin square design. Each experimental period included 15 days for adaptation and 5 days for sampling. Supplementing taurine did not affect the ruminal pH or concentrations of ammonia nitrogen and volatile fatty acids (P > 0.10), but linearly increased the ruminal concentrations of taurine (P < 0.001) and microbial crude protein (P=0.041). Supplementing taurine linearly increased the neutral detergent fiber digestibility (P=0.018), and tended to linearly increase dry matter digestibility (P=0.095), tended to increase the fecal nitrogen excretion (P=0.065) and increased the urinary taurine excretion (P < 0.001). Supplementing taurine quadratically increased the plasma concentration of triglycerides (P=0.017), tended to linearly decrease growth hormone (P=0.074), but did not affect other plasma parameters (P > 0.10). Supplementing taurine modified the rumen bacterial community and increased the ruminal concentration of taurine metabolite 2-hydroxyethoxysulfonic acid (P < 0.001). It was concluded that taurine improved ruminal microbial crude protein synthesis and increased fiber digestibility through modifying rumen bacterial community. It is necessary to clarify the ruminal hydrolysis of taurine in steers. © 2023 Society of Chemical Industry.

Effects of Different Dietary Protein Level on Growth Performance, Rumen Fermentation Characteristics and Plasma Metabolomics Profile of Growing Yak in the Cold Season.

This experiment was aimed to compare the effects of two diets with different protein content on the growth performance, immune indexes, rumen fermentation characteristics and plasma metabolomics of growing yak in the cold season. A total of 24, 2-year-old healthy yaks with similar body weight (142.9 ± 3.56 kg) were randomly allocated to two isoenergetic diets with different protein content (10 vs 14%) according to a non-paired experimental design, and the protein of the diets was increased by increasing soybean meal, rapeseed meal and cottonseed meal. The growth performance experiment lasted 56 days. Four days before the end of the growth experiment, the digestion trial was conducted, and the rumen fluid and plasma was collected for measurement. The results showed that the average daily feed intake (p < 0.001) and average daily gain (p = 0.006) of yak fed a high-protein diet was significantly greater, while the feed conversion ratio was lower (p = 0.021) than that of yaks fed a low-protein diet. Plasma aspartate aminotransferase (p = 0.002), alanine aminotransferase (p < 0.001), malondialdehyde (p = 0.001), tumor necrosis factor-α (p = 0.032) and interferon-γ (p = 0.017) of the high-protein group were significantly lesser, whereas superoxide dismutase (p = 0.004) and interleukin-2 (p = 0.007) was significantly greater than that of the low-protein group. The rumen microbial crude protein (p < 0.047) and crude protein digestibility (p = 0.015) of yak fed a high-protein diet was significantly greater than that of the low-protein group. The metabolomics results showed that yaks fed a high-protein diet were elevated in protein digestion and absorption, arginine and proline metabolism, tryptophan metabolism, purine metabolism, butanoate metabolism, taste transduction, pyrimidine metabolism, pantothenate and CoA biosynthesis, glutathione metabolism and renin secretion pathways. It is concluded that a high-protein diet in the cold season can promote rumen microbial crude protein synthesis, enhance antioxidant and immune function and promote growth performance of yaks.

Predicting microbial crude protein synthesis in cattle from intakes of dietary energy and crude protein.

Accurate predictions of microbial crude protein (MCP) synthesis are needed to predict metabolizable protein supply in ruminants. Since 1996, the National Academies of Sciences, Engineering, and Medicine series on beef cattle nutrient requirements has used the intake of total digestible nutrients (TDN) to predict ruminal MCP synthesis. Because various tabular energy values for feeds are highly correlated, our objective was to determine whether intakes of digestible energy (DE), metabolizable energy (ME), and net energy for maintenance (NEm) could be used as predictors of MCP synthesis in beef cattle. A published database of 285 treatment means from experiments that evaluated MCP synthesis was updated with 50 additional treatment mean observations. When intakes of TDN, fat-free TDN, DE, ME, NEm, dry matter, organic matter, crude protein (CP), ether extract, neutral detergent fiber, and starch were used in a stepwise regression analysis to predict MCP, only intakes of DE and CP met the P < 0.10 criterion for entry into the model. Mixed-model regression analyses were used to adjust for random intercept and slope effects of citations to evaluate intake of DE alone or in combination with CP intake as predictors of MCP synthesis, and the intakes of TDN, ME, and NEm as alternatives to DE intake. Similar precisions in predicting MCP synthesis were obtained with all measures of energy intake (CV = root mean square error [RMSE] as a percentage of the overall mean MCP varied from 9% to 9.67%), and adding CP intake to statistical models increased precision (CV ranged from 8.43% to 9.39%). Resampling analyses were used to evaluate observed vs. predicted values for the various energy intake models with or without CP intake, as well as the TDN-based equation used in the current beef cattle nutrient requirements calculations. The coefficient of determination, concordance correlation coefficient, and RMSE of prediction as a percentage of the mean averaged 0.595%, 0.730%, and 28.6% for the four measures of energy intake, with average values of 0.630%, 0.757%, and 27.4%, respectively, for equations that included CP intake. The TDN equation adopted by the 2016 beef cattle nutrient requirements system yielded similar results to newly developed equations but had a slightly greater mean bias. We concluded that any of the measures of energy intake we evaluated can be used to predict MCP synthesis by beef cattle and that adding CP intake improves model precision.

Ruminal Degradation of Taurine and Its Effects on Rumen Fermentation In Vitro

Taurine accounts for approximately 0.1% of an animal’s body. It cannot be used for protein synthesis but plays a wide range of important roles in the animal body. Taurine does not exist in plants, while mammals can only synthesize 30–40% of the taurine they need. Supplementing taurine to beef cattle may be necessary to improve their nutrient utilization and health status. However, no data are available regarding the metabolism of taurine in the rumen. Two in vitro trials were conducted to investigate the ruminal degradability of taurine and its effects on rumen fermentation. In Trial 1, Tilley and Terry’s in vitro rumen fermentation technique was used for incubation. As treatments, two levels of taurine, i.e., 0 and 10 mg, were added into plastic tubes containing 0.4000 g of feed mixture with a calibrated volume of 50 mL. Three adult cattle fitted with rumen cannulas were used as the donors for rumen fluid. The incubation was carried out at 39 °C for 48 h. The results showed that the taurine degradability increased with incubation time (p &lt; 0.001) while its 2 h-degradability reached 99%. Taurine decreased the 48 h-dry matter degradability (DMD) (p = 0.008) and increased the 24 h- and 48 h-pH (p = 0.005; p = 0.018), respectively. In Trial 2, the Hohenheim gas test was used for incubation. Four levels of taurine, i.e., 0, 5, 10 and 20 mg, were added into glass syringes containing 0.2000 g feed mixture with a calibrated volume of 100 mL as treatments. The rumen fluid donors were the same as in Trial 1. The incubation was carried out at 39 °C for 48 h. The results showed that taurine increased the 48 h-pH (p &lt; 0.001) linearly, decreased the cumulative gas production (p &lt; 0.001) and the total volatile fatty acids (VFA) concentration (p = 0.014), and quadratically affected the ammonia–nitrogen (p &lt; 0.001) and microbial crude protein (MCP) concentrations (p &lt; 0.001). It was concluded that taurine was highly degradable in rumen fermentation. Taurine inhibits ruminal fermentation by decreasing DMD, VFA and gas production while improving MCP synthesis on a dose-dependent basis.

The Effect of Forage Source and Concentrated Liquid Feedstuff Supplementation on Improving the Synchronization of Ruminant Dietary Energy and Nitrogen Release In Vitro

This study aimed to investigate the effect of supplementation with a mixture of molasses and condensed molasses fermentation solubles (M-CMS) in different synchronization diets formulated with different forage sources in an attempt to improve the fermentation efficiency of diets by M-CMS. In the first experiment, three levels of M-CMS (N: 0%; L: 1.75%; and H: 3.50%) were supplied to diets with or without corn silage to evaluate the supplementation effect on the diet with a synchrony index (SI) of 0.80. In the second experiment, diets containing different corn silage levels (60 or 30% of the forage source) were used to evaluate the effects of M-CMS supplementation on higher SI (at 0.88). The in vitro digestibility, fermentation products, microbial crude protein (MCP), and gas kinetic parameters were determined after 48 h of fermentation. The results demonstrated that M-CMS supplementation improved MCP synthesis in both diets with low and high SI, but did not enhance digestibility. M-CMS supplementation was beneficial to the fermentation stability and extent. It also affected the gas kinetic parameters of the fast- and slow-degradation fractions during fermentation. M-CMS supplementation improved MCP synthesis in diets containing less corn silage. The forage source and degradation rate of individual ingredients should be considered simultaneously to enhance the rumen fermentation efficiency. M-CMS provided a practical choice to further improve MCP synthesis and fermentation stability, even in a diet with high SI.

Excreção de creatinina e derivados de purina e síntese microbiana em cordeiros alimentados com farinha de vagem de Samanea saman

ABSTRACT Evaluated the levels of rain tree (Samanea saman) pod meal (RTPM) (0, 10, 15, 20 and 25%) replacing maize in the dry matter of the diet on intake of DM, CP and ME, creatinine and total purine derivatives excretion in urine and microbial protein synthesis in lambs. Twenty-five uncastrated Bergamasca lambs were used, with an initial body weight of 24±5kg and an average age of 120 days. The experimental design was completely randomized, with five treatments and five replications. The trial lasted 84 days and the 24h and spot urine collections were performed in the last day of the experiment. The intake was not affected (P&gt;0.05), the urine volume and daily creatinine excretion were influenced (P&lt;0.05) by RTPM replacing maize, observing increasing linear effect and cubic variation (P&lt;0.05), respectively. The cubic and quadratic components were significant (P&lt;0.05) for the excretion of total purine derivatives, absorbed purines, and microbial synthesis. The cubic variation, with peaks at 5% and 18% replacement for urinary excretion of creatinine and purine derivatives, indicates that the levels used of RTPM affected the renal activity of lambs. Substitution of maize by RTPM up to 10% enhances efficiency of rumen microbial crude protein synthesis.

Effect of wilting and lactic acid bacteria inoculant on in situ and in vitro determined protein value of grass silages

The objective of this study was to evaluate the effect of dry matter (DM) concentration and the use of lactic acid bacteria (LAB) inoculant on the protein value of grass silages. Grass samples containing 170 g DM/kg fresh material were wilted to different DM concentrations (310, 390, 420, 470, 530, 580, 600 g/kg fresh material) before ensiling. Half of the grass material at respective DM was treated with LAB, the other half remained untreated (control, CON). Ruminal degradation of organic matter (OM) and crude protein (CP) was determined using the in situ technique. For this, silage samples were incubated for 2, 4, 8, 16, 24, 48 and 72 h. Rumen undegraded CP (RUCP) was derived from in situ CP degradation. Microbial CP (MCP) synthesis was assumed to be 181 g per kg fermented OM. Post-ruminal CP (prCP) was defined as the sum of RUCP and MCP. Effective prCP in situ (prCPkin situ) was calculated for passage rates (k) of 0.02, 0.04 and 0.06/h. In addition, the modified Hohenheim gas test (modHGT) was used to determine effective prCP in vitro (prCPkin vitro) for the same passage rates. The DM linearly increased prCPk in situ in CON (P < 0.001) and LAB (P < 0.001). This was caused by both increased RUCP in the range of 580–600 g DM (P < 0.001) and increased MCP (P < 0.001) due to higher amount of water-soluble carbohydrates in the more intensively wilted silages. The use of LAB increased RUCP (P < 0.001) but decreased the calculated MCP content (P < 0.001). Therefore, these effects compensated each other leading to only slightly lower prCPk in situ for LAB (P < 0.05). The positive effect of DM on prCPkin situ was confirmed in vitro (P < 0.001) showing no effect of the inoculant. Based on both methods prCPk increased to a small extent with 2.3 – 4.9 g/kg OM (P < 0.001), when DM increases by 100 g/kg fresh material, depending on the assumed passage rate. Therefore, wilting and LAB addition to grass have the potential to improve protein value of grass silage. Both methods delivered similar estimates for effective prCP. But modHGT appeared to be superior to the in situ technique by being more sensitive, not requiring separate estimation of MCP and the assumption of a certain efficiency value, and by having lower operating expenses. The results of this study show the potential of the modHGT, however further studies are required to standardize and validate this technique and to evaluate the effect of wilting grass on animal performance.

Profiles of Odd- and Branched-Chain Fatty Acids and Their Correlations With Rumen Fermentation Parameters, Microbial Protein Synthesis, and Bacterial Populations Based on Pure Carbohydrate Incubation in vitro.

The objectives of this study were to evaluate changes in profiles of odd- and branched-chain fatty acids (OBCFA), including pentadecanoic acid (C15:0), 13-methyltetradecanoic acid (iso-C15:0), 12-methyltetradecanoic acid (anteiso-C15:0), 14-methylpentadecanoic acid (iso-C16:0), heptadecanoic acid (C17:0), 15-methylhexadecanoic acid (iso-C17:0), and 14-methylhexadecanoic acid (anteiso-C17:0) during in vitro fermentation of pure carbohydrates mixtures in the buffer-rumen fluid. The second objective was to correlate the changes in the OBCFA profile to the corresponding changes in ruminal fermentation parameters, microbial crude protein (MCP) synthesis, and bacterial populations. Five pure carbohydrates mixtures containing different cellulose: starch (C:S) ratios, i.e., 0:100, 25:75, 50:50, 75:25, and 100:0, were incubated for 6, 12, 18, and 24 h in vitro. The results showed that there was significant interaction (P < 0.05) between C:S and incubation time for changes in all OBCFA profiles, except iso-C17:0. The highest concentration of total OBCFA (3.94 mg/g dry matter; DM) was observed in the residues after 24 h of fermentation when the C:S was 0:100, while the lowest concentration of OBCFA (1.65 mg/g DM) was produced after 6 h of incubation when the C:S was 50:50. The correlation analysis revealed that the concentration of iso-C16:0 might be a potential marker for the estimation of total volatile fatty acids (ρ = 0.78) and MCP synthesis (ρ = 0.82) in the rumen. Compared to starch degrading bacteria, cellulolytic bacteria had stronger correlations with OBCFA concentrations, and the strongest correlation was found between the population of Ruminococcus flavefaciens with C15:0 concentration (ρ = 0.70). Notably, this is the first paper reporting relationship between OBCFA with rumen fermentation products and microbial protein synthesis based on fermentation of pure carbohydrates mixtures in vitro, and thus avoid confounding interference from dietary protein and fat presence in the in vivo studies. However, more in-depth experiments are needed to substantiate the current findings.

Metabolizable Protein: 1. Predicting Equations to Estimate Microbial Crude Protein Synthesis in Small Ruminants.

Microbial crude protein (MCP) produced in rumen could be estimated by a variety of protocols of experimental sampling and analysis. However, a model to estimate this value is necessary when protein requirements are calculated for small ruminants. This model could be useful to calculate rumen degradable protein (RDP) requirements from metabolizable protein (MP). Then, our objective was to investigate if there is a difference in MCP efficiency between sheep and goats, and to fit equations to predict ruminal MCP production from dietary energy intake. The database consisted of 19 studies with goats (n = 176) and sheep (n = 316), and the variables MCP synthesis (g/day), total digestible nutrients (TDN), and organic matter (OM) intakes (g/day), and OM digestibility (g/kg DM) were registered for both species. The database was used for two different purposes, where 70% of the values were sorted to fit equations, and 30% for validation. A meta-analytical procedure was carried out using the MIXED procedure of SAS, specie was considered as the fixed dummy effect, and the intercept and slope nested in the study were considered random effects. No effect of specie was observed for the estimation of MCP from TDN, digestible Organic Matter (dOM), or metabolizable energy (ME) intakes (P > 0.05), considering an equation with or without an intercept. Therefore, single models including both species at the same fitting were validated. The following equations MCP (g/day) = 12.7311 + 59.2956 × TDN intake (AIC = 3,004.6); MCP (g/day) = 15.7764 + 62.2612 × dOM intake (AIC = 2,755.1); and MCP (g/day) = 12.7311 + 15.3000 × ME intake (AIC = 3,007.3) presented lower values for the mean square error of prediction (MSEP) and its decomposition, and similar values for the concordance correlation coefficient (CCC) and for the residual mean square error (RMSE) when compared with equations fitted without an intercept. The intercept and slope pooled test was significant for equations without an intercept (P < 0.05), indicating that observed and predicted data differed. In contrast, predicted and observed data for complete equations were similar (P > 0.05).

Effects of including physically effective fiber from sugarcane in whole corn grain diets on the ingestive, digestive, and ruminal parameters of growing beef bulls

The objective of this study was to evaluate the inclusion of physically effective fiber (peNDF) from sugarcane in feedlot diets containing whole corn grain on ingestive, digestive, and ruminal parameters. Five rumen-cannulated Nellore bulls (BW = 393 ± 9 kg) distributed in an incomplete 5 × 5 Latin square received diets containing 5% (D5), 15% (D15), 25% (D25), or 35% (D35) sugarcane. All diets included a mineral-protein supplement. Omasal digesta collection and fecal spot collection were carried out to estimate ruminal and total digestibility. The ruminal contents were emptied to calculate ingestion (ki), passage (kp), and digestion (kd) rates. The linear, quadratic, and cubic effects of including sugarcane (i.e., different peNDF contents) were evaluated using orthogonal contrasts. The intake of total digestible nutrients (TDN, P = 0.06), dry matter (DM, P = 0.03), and organic matter (OM, P = 0.03) showed a quadratic pattern, with the highest estimated values occurring between 6.14 and 10.2% of peNDF. Ruminal digestibility [%, (P = 0.01) and kg/d, (P = < 0.01)] and total digestibility (kg/d, P = 0.03) of OM, ki (P = < 0.01), kp (P = 0.01) and kd (P = < 0.01) rates of OM, ki (P = 0.07), kp (P = 0.01), and kd (P = 0.05) rates of neutral detergent fiber (NDF) and microbial crude protein synthesis (MPS) (P = < 0.01) were also maximized, with inclusion levels between 6.14 and 10.2% of peNDF, although the efficiency of MPS tended to increase linearly (P = 0.08). The total concentration of volatile fatty acids (VFA) decreased linearly (P = 0.03), while the rumen ammonia pool [concentration (mmol/L) x volume of rumen liquid (L)] increased linearly (P = < 0.01). Ruminal pH responded linearly with the addition of sugarcane to the diet. We conclude that feedlot animals might benefit from diets containing between 6.14 and 10.2% of peNDF when whole corn grain diets are used.

The effects of rumen nitrogen balance on nutrient intake, nitrogen partitioning, and microbial protein synthesis in lactating dairy cows offered different dietary protein sources

The aim was to study the effects of rumen N balance (RNB), dietary protein source, and their interaction on feed intake, N partitioning, and rumen microbial crude protein (MCP) synthesis in lactating dairy cows. Twenty-four lactating Holstein cows were included in a replicated 4 × 4 Latin square experimental design comprising four 20-d periods, each with 12 d of adaptation to the experimental diets and 8 d of sampling. The dietary treatments followed a 2 × 2 factorial arrangement (i.e., 4 treatments) with 2 main protein sources [faba bean grain (FB) and SoyPass (SP; Beweka Kraftfutterwerk GmbH, Heilbronn, Germany)] offered at 2 dietary RNB levels each [0 g/kg of dry matter, DM (RNB0) and -3.2 g/kg of DM (RNB-)]. The RNB was calculated as the difference between dietary crude protein (CP) intake and the rumen outflow of undegraded feed CP and MCP and divided by 6.25. Composition of concentrate mixtures was adjusted to create diets with desired RNB levels. Each of these protein sources supplied ≥35% of total dietary CP. Both diets for each protein source were isoenergetic but differed in CP concentrations. The DM intake (kg/d) was lower for RNB- than for RNB0 in diets containing FB, whereas no differences were seen between the RNB levels for SP diets. The RNB- decreased N intake and urinary N excretion but increased milk N use efficiency in both FB and SP diets, with greater differences between the RNB levels for FB diets than for SP diets. Similarly, duodenal MCP synthesis (g/kg of digestible organic matter intake) estimated from purine derivatives in the urine was lower for RNB- than for RNB0 in FB diets but similar between the RNB levels in diets containing SP. Low RNB of approximately -65 g/d (approximately -3.2 g/kg of DM) in diets reduced feed intake, N balance, and performance in high-yielding dairy cows with possibly more pronounced effects in diets containing rapidly degradable protein sources.

Effect of Sulfur and Urea Fortification of Fresh Cassava Root in Fermented Total Mixed Ration on the Improvement Milk Quality of Tropical Lactating Cows.

The aim of the present research was to determine the influence of sulfur and urea combined with fresh cassava root in fermented total mixed ration (FTMR) on digestibility, fermentation in the rumen, blood metabolite, milk yield, and milk quality in tropical lactating dairy cows. Four mid-lactation Thai Holstein–Friesian crossbred cows were studied. Pre-experiment milk yield was 12.7 ± 0.30 kg/day, and the body weight was 495 ± 40.0 kg. Animals were evaluated in a 2 × 2 factorial in a 4 × 4 Latin square design to receive diets followed by: factor A, which was a dose of sulfur inclusion at 1.0% and 2.0%, and factor B, which was level of urea inclusion at 1.25% and 2.5% DM in FTMR. The hydrogen cyanide (HCN) concentrations reduced 99.3% to 99.4% compared with fresh cassava root when FTMR was supplemented with 1.0% and 2.0% sulfur, respectively. Intake of crude protein was increased based on urea level addition (p < 0.05). Blood thiocyanate concentration was increased by 21.6% when sulfur was supplemented at 2.0% compared to 1.0% (p < 0.05). There was no difference in protozoal concentration, whereas bacterial populations at 4 h after feeding were significantly greater by 6.1% with the FTMR supplemented with 2.0% sulfur and 2.5% urea (p < 0.01). Allantoin concentrations, excretion, absorption, and microbial crude protein showed significant interactions between sulfur levels and urea levels in cows fed diets supplemented with 2.0% sulfur and 2.5% urea (p < 0.05). The molar ratios of the volatile fatty acid (VFA) profile were affected by dietary FTMR (p < 0.01). Furthermore, propionic acid increased by 4.6% when diets were supplemented by 2.5% sulfur (p < 0.01). Milk fat and total solids increased when feed was supplemented with 2.0% sulfur and 2.5% urea (p < 0.05). The diets supplemented with 2.0% sulfur levels resulted in greater concentrations of milk thiocyanate (p < 0.05). The somatic cell count was significantly reduced throughout the experiment with increasing sulfur supplementation (p < 0.05). Animals fed diets supplemented with 2.0% sulfur exhibited a decreased somatic cell count by 18.3% compared with those fed diets supplemented with 1.0% sulfur. Thus, inclusion of 2.0% sulfur with 2.5% urea in FTMR containing fresh cassava root improved digestibility, ruminal fermentation, microbial crude protein synthesis, and milk qualities in dairy cows.

Dietary phase-feeding as feedlot strategy for Santa Ines lambs: performance, N retention and meat quality

• Diets with 130 g/kg of CP optimize the N utilization for production for Santa Ines lamb. • The results suggest that no benefits are obtained in performance and meat quality when phase feeding is applied, or when more than 130 g of CP/kg DM is provided to Santa Ines sheep. We executed two studies to investigate the possibility of reducing crude protein (CP) content throughout feedlot of growing lambs, when they are changing their body composition, and passing from most protein retention to fat deposition for finishing. A performance trial (EXP 1) with 40 Santa Ines crossbred sheep (initial body weight (BW) of 15.6±1.6 kg) were carried out in a completely randomized design, with four treatments and 10 repetitions. The EXP 1 lasted a total of 85 days, with 15 for adaptation and 70 for data collection. The investigated diets were formulated with two CP contents, in which 150 g of CP/kg DM (High CP (HCP)) diets represented the adequate nutritional requirement for growing lambs, or 130 g of CP/kg DM (Low CP (LCP diets)), which represented the reduced content. We also evaluated the feedlot phases, in which the initial phase-feeding (IPF) comprised day 1 to 35, and the final phase-feeding (FPF) comprised day 36 to 70. The combination of these factors resulted in the following treatments (T): T1 - Animals fed with the lower CP content during all the feedlot period, 130 in IPF and 130 g of CP/kg DM in FPF (T1: LCP-LCP); T2-Animals were fed with increasing content of CP along feedlot (T2: LCP-HCP); T3- Animals were fed with decreasing content of CP during the phases (T3: HCP-LCP); T4 - Animals were fed with the greater CP content during all feedlot period (T4: HCP-HCP). We carried out a second study to investigate the ruminal fermentation parameters (EXP 2). Four adult Santa Ines sheep (average BW of 60.6±10.6 kg), fistulated in rumen, were distributed in four 2 × 2 Latin squares. The same CP contents from EXP 1 were evaluated: LCP diets (130 g of CP/kg DM) and HCP diets (150 g of CP/kg DM). There was effect (P> 0.05) of CP contents in FPF on CP intake and urinary N excretion, being higher for the animals fed with HCP diets. The phase-feeding did not affect the microbial CP synthesis and microbial efficiency (P> 0.05), and also did not affect (P > 0.05) meat quality. The animals fed with LCP or HCP diets in both IPF and FPF presented a similar ADG (P = 0.65 and P > 0.15, respectively) and final BW (FBW, P = 0.66 and P= 0.24, respectively). Sheep fed with HCP diets had higher concentrations of ruminal ammoniacal N (N-NH 3 , P < 0.01), but demonstrated similar (P > 0.05) volatile fatty acids (VFA) production. Our results demonstrate that no benefits on rumen fermentation, performance and meat quality were found when more than LCP diets was provided during the feedlot, nor when phase-feeding was applied to crossbred Santa Ines lambs.