In situ ruminal degradation of amino acids and in vitro protein digestibility of undegraded CP of dried distillers’ grains with solubles from European ethanol plants

Predicting ruminal degradability and chemical composition of corn silage using near-infrared spectroscopy and multivariate regression

The aim of this study was to develop and validate regression models to predict the chemical composition and ruminal degradation parameters of corn silage by near-infrared spectroscopy (NIR). Ninety-four samples were used to develop and validate the models to predict corn silage composition. A subset of 23 samples was used to develop and validate models to predict ruminal degradation parameters of corn silage. Wet chemistry methods were used to determine the composition values and ruminal degradation parameters of the corn silage samples. The dried and ground samples had their NIR spectra scanned using a poliSPECNIR 900-1700 model NIR sprectrophotometer (ITPhotonics S.r.l, Breganze, IT.). The models were developed using regression by partial least squares (PLS), and the ordered predictor selection (OPS) method was used. In general, the regression models obtained to predict the corn silage composition (P>0.05), except the model for organic matter (OM), adequately estimated the studied properties. It was not possible to develop prediction models for the potentially degradable fraction in the rumen of OM and crude protein and the degradation rate of OM. The regression models that could be obtained to predict the ruminal degradation parameters showed correlation coefficient of calibration between 0.530 and 0.985. The regression models developed to predict CS composition accurately estimated the CS composition, except the model for OM. The NIR has potential to be used by nutritionists as a rapid prediction tool for ruminal degradation parameters in the field.

Linkage of in situ ruminal degradation of crude protein with ruminal degradation of amino acids and phytate from different soybean meals in dairy cows

The objectives of this study were to determine the range in ruminal degradability of crude protein (CP) and intestinal digestibility of rumen undegradable protein in commercial soybean meal (SBM) and to investigate the range in in situ ruminal AA and phytate (InsP6) degradation and their relationship to CP degradation. An in situ study was conducted using 3 lactating Jersey cows with permanent rumen cannulas. Seventeen SBM variants from Europe, Brazil, Argentina, North America, and India were tested for ruminal CP and AA degradation, and in vitro intestinal digestibility of rumen undegradable protein. Nine variants were used to investigate the ruminal degradation of InsP6. The estimated rapidly degradable fraction (a) of CP showed an average value of 4.5% (range: 0.0%-9.0%), the slowly degradable fraction (b) averaged 95% (91%-100%), and the potential degradation was complete for all 17 SBM variants. The degradation of fraction b started after a mean lag phase of 1.7 h (1.1-2.0 h) at an average rate (c) of 10% per hour, but with a high range from 4.5% to 14% per hour. Differences in the degradation parameters induced a considerable range in CP effective degradation at a rumen passage rate of 6% per hour (CPED6) from 38% to 67%; hence, the concentration of rumen undegradable protein varied widely from 33% to 62%. The range in AA degradation between the SBM variants was high, with Ser showing the widest range, from 28% to 96%, and similar for the other AA. The regression equations showed close relationships between CP and AA degradation after 16 h of in situ incubation. However, the slopes of the linear regressions were significantly different between AA, suggesting that degradation among individual AA differs upon a change in CP degradation. The concentrations of InsP6 and myo-inositol pentakisphosphate in bag residues in the in situ study decreased constantly with longer ruminal incubation times. The ruminal degradation parameters of InsP6 ranged from 11% to 37% for fraction a, 63% to 89% for fraction b, and from 7.7% to 21% per hour for degradation rate c, with average values of 21%, 79%, and 16% per hour, respectively. The calculated InsP6 effective degradation at a rumen passage rate of 6% per hour (InsP6ED6) varied from 61% to 84% among the SBM variants. Significant correlations were detected between InsP6ED6 and CPED6 and between InsP6ED6 and chemical protein fractions A, B1, B2, B3, and C. Linear regression equations were developed to predict ruminal InsP6 degradation using CPED6 and chemical protein fractions B3 and C chosen by a stepwise selection procedure. We concluded that a high range in CP, AA, and InsP6 degradation exists among commercial SBM, suggesting that general degradability values may not be precise enough for diet formulation for dairy cows. Degradation of CP in SBM may be used to predict rumen degradation of AA and InsP6 using linear regression equations. Degradation of CP and InsP6 could also be predicted from the chemical protein fractions.

In Vitro Rumen Fermentation and Post-Ruminal Digestibility of Sorghum-Soybean Forage as Affected by Ensiling Length, Storage Temperature, and Its Interactions with Crude Protein Levels

The study aimed to evaluate the effects of ensiling length, storage temperature, and its interaction with crude protein (CP) levels in sorghum−soybean forage mixtures on in vitro rumen fermentation and post-ruminal digestibility of nutrients. The dietary treatments consisted of fresh forages (d 0) and silages of sorghum and soybean stored indoors or outdoors for 75 and 180 d with additional ingredients to make two dietary CP levels, 90 and 130 g/kg dry matter (DM) and a forage-to-concentrate ratio of 80 to 20. An in vitro procedure was conducted using the ANKOM RF technique to study rumen fermentation. The dietary treatments were incubated in duplicate for 8 and 24 h in three runs. After each incubation time, in vitro rumen fermentation parameters were measured, and the protozoa population was counted using a microscope. Post-ruminal digestibility was determined using the pepsin and pancreatic solubility procedure. Cumulative gas production (GP) increased quadratically with ensiling length (8 h, p < 0.01; 24 h, p = 0.02), and the GP differed between CP levels at both incubation times (p < 0.01). However, total short-chain fatty acid (SCFA) concentrations in rumen inoculum increased quadratically with ensiling length (p < 0.01; for both incubation times), and interaction between ensiling length and CP levels was observed in proportions of acetate and propionate after 24 h of incubation (p < 0.01; for both incubation times). Similarly, an interaction between ensiling length and CP levels was found in the proportion of valerate after 24 h of incubation (p < 0.01). There was a quadratic response to ensiling length in the NH4−N concentration after 8 h (p < 0.01) and 24 h (p < 0.05), and the CP level also differed (p < 0.01) at both incubation times. The ciliate protozoa count after 24 h was higher in low CP diets than in high CP diets (p = 0.04). The amount of CP in the undegraded substrate at both incubation times differed between CP levels (p < 0.01; for both incubation times). An interaction effect between ensiling length and storage temperature after 8 h (p = 0.02) and 24 h (p < 0.01) was observed for intestinal CP digestibility. The effect of CP levels on intestinal CP digestibility differed after 8 h (p < 0.01) and 24 h (p < 0.01). In conclusion, increasing ensiling length beyond 75 d reduced CP digestibility, and additional CP inclusion did not ameliorate this.

Diets for Dairy Cows with Different Proportions of Crude Protein Originating from Red Clover Silage versus Soybean Meal: Ruminal Degradation and Intestinal Digestibility of Amino Acids

The purpose was to assess the effect of exchanging crude protein (CP) of soybean meal (SBM) with red clover silage (RCS) in total mixed rations (TMR) on ruminal degradation and intestinal digestibility (ID) of essential amino acids (EAA). Four TMR and their individual feed components were studied. The TMR were composed of forage and concentrates (75:25), with proportions of RCS in TMR of 0.15, 0.30, 0.45, and 0.60 on a dry matter basis, resulting in diet groups RCS15, RCS30, RCS45, and RCS60, respectively. The ruminal degradation of EAA was determined using the nylon bag technique. For this, samples of TMR and their individual feed components were ruminally incubated for 16 h. The feed residues of TMR obtained after 16 h of incubation were used for the determination of ID of EAA using the mobile-bag technique. Increasing RCS and reducing SBM proportions linearly increased (p < 0.01) the in situ ruminal degradation of individual EAA from 75.5% to 83.5%. The degradation of EAA followed the trend of CP degradation among TMR, except for Cys that was lower (p < 0.05) than that of CP in RCS60 (79.7% vs. 86.3%). The degradation of EAA in individual feed ingredients not always corresponded to the degradation of CP and was feed dependent. Increasing the proportions of RCS in the TMR linearly reduced (p < 0.001) the ID of EAA (except for Ile) from 78.2% to 67.3%. However, the ID of EAA did not always reflect the ID of CP, and in general, the differences between the ID of CP and EAA increased as RCS increased in the TMR. The ID values of most of the EAA were similar (p > 0.05) to ID of CP in RCS15 and RCS30, while they mostly differed (p < 0.05) in RCS45 and RCS60, and being higher for EAA than CP (except for Cys that was lower than CP, p < 0.05). Similar trends were observed for intestinal absorbable AA, resulting in higher values (p < 0.05) of intestinal absorbable for all EAA than of CP in diet RCS60. In conclusion, increasing levels of RCS in TMR reduced the extent of EAA flow into the small intestine, the ID of EAA, and consequently the intestinal absorbable EAA. Therefore, accurate determination of metabolizable AA must be considered for optimal diet formulation when including high proportions of RCS in diets of high-producing dairy cows.

Growth Performance and Carcass Traits Responses to Dried Distillers' Grain with Solubles Feeding of Growing Awassi Ram Lambs

Simple Summary

Corn grain is considered to be the most important crop in the world. Corn dried distiller grains with solubles is a by-product of ethanol production. It is included at 0, 125, or 25 g/kg in lambs’ diets. This inclusion reduced the cost of diet, indicating the good possibility of using it in small ruminant diets.

Abstract

This study considers the impact of dried distillers’ grain with solubles (DDGS) in diets of lambs. Randomly; 27 lambs were distributed to one of three diets. Diets were: a control diet (CON; n = 9), a 125 (DDGS125; n = 9) or a 250 g/kg DDGS (DDGS250; n = 9) of dietary dry matter (DM). The lambs were fed using these diets for 91 days. To assess carcass traits; five lambs were randomly selected at the end of the study. No significant differences were detected in intake and digestibility of DM; crude protein and fiber. Average daily gain did not differ among diets. Carcass characteristics did not differ among diets. With the exception of shear force and redness, which were greater in DDGS250 than in DDGS125 and CON diets, meat quality parameters were unaffected. Eye muscle area decreased in DDGS125 than in DDGS250 and CON diet. These results demonstrate that the feeding of lambs on DDGS at 125 or 250 g/kg DM did not have any impact on growth. These diets only had a simple effect on the characteristics of carcass and meat quality. These results suggest that it would be suitable to introduce these feeds into sheep nutrition in the future.

Replacing maize silage plus soybean meal with red clover silage plus wheat in diets for lactating dairy cows

The objectives of this study were to evaluate the effects of replacing maize silage plus soybean meal with red clover silage (RCS) plus wheat on feed intake, diet digestibility, N partitioning, urinary excretion of purine derivatives, and milk production in dairy cows. Forty-four lactating German Holstein cows were used in a 4 × 4 Latin square design with 21-d periods composed of a 13-d adaptation phase followed by an 8-d sampling phase. Experimental diets offered as total mixed ration consisted of a constant forage-to-concentrate ratio (75:25) with targeted proportions of RCS-to-maize silage of 15:60 (RCS15), 30:45 (RCS30), 45:30 (RCS45), and 60:15 (RCS60) on a dry matter (DM) basis. Increasing the proportion of RCS plus wheat in the diet decreased linearly the intake of DM from 22.4 to 19.8 kg/d, and of organic matter from 21.1 to 18.1 kg/d. The apparent total tract digestibility (ATTD) of DM and organic matter did not differ across diets and averaged 68.4 and 70.5%, respectively. However, ATTD of N decreased linearly from 68.5 to 63.2%, whereas ATTD of neutral detergent fiber and acid detergent fiber increased linearly from 50.4 to 59.6% and from 48.4 to 57.7%, respectively, when increasing the proportion of RCS plus wheat. Fecal N excretion increased from 31.6 (RCS15) to 37.2% (RCS60) of N intake, whereas urinary N excretion was the lowest (32.8% of N intake) with RCS45. Hence, N efficiency (milk N/N intake) decreased linearly with incremental levels of RCS plus wheat, being the lowest when feeding RCS60 (25.4%), probably due to increased nonprotein N proportion in total dietary N. Urinary excretion of purine derivatives decreased linearly from 378 to 339 mmol/d, which suggests that increasing levels of RCS plus wheat reduced the microbial crude protein flow at the duodenum. Milk yield and milk protein concentration declined linearly from 35.9 to 30.2 kg/d and from 3.20 to 3.01%, respectively, when increasing the proportion of RCS plus wheat. In conclusion, caution should be taken before introducing high levels of RCS plus wheat in diets of high-yielding dairy cows. However, RCS plus wheat can be included up to 30% of the dairy cow diet (DM basis) without a reduction in lactation performance.

In vitro microbial protein synthesis, ruminal degradation and post-ruminal digestibility of crude protein of dairy rations containing Quebracho tannin extract

This study evaluated the effects of Quebracho tannin extract (QTE) on in vitro ruminal fermentation, chemical composition of rumen microbes, ruminal degradation and intestinal digestibility of crude protein (iCPd). Three treatments were tested, the control (basal diet without QTE), the basal diet with 15 g QTE/kg dry matter (DM) and the basal diet with 30 g QTE/kg DM. The basal diet contained (g/kg DM): 339 grass silage, 317 maize silage and 344 concentrate. In vitro gas production kinetic was determined using the Hohenheim gas test (Experiment 1). The Ankom RF technique, a batch system with automatic gas pressure recordings, was used to determine in vitro production of short-chain fatty acids (SCFA) and ammonia-nitrogen concentration (NH₃ -N), as well as nitrogen and purine bases content in liquid-associated microbes (LAM) and in a residue of undegraded feed and solid-associated microbes (Feed+SAM) (Experiment 2). Ruminal degradation and iCPd were determined using the nylon bag technique and the mobile nylon bag technique, respectively (Experiment 3). Gas production (Experiment 1), total SCFA and NH₃ -N (Experiment 2) decreased with increasing QTE levels. Microbial mass and composition of LAM were not affected by QTE, but total mass of Feed+SAM linearly increased, likely due to decreased substrate degradation with increasing QTE levels. The total amount of N in microbial mass and undegraded feed after the in vitro incubation increased with increasing QTE levels, suggesting a potential greater N flow from the rumen to the duodenum. In contrast to in vivo studies with the same QTE, no effects were detected on ruminal effective degradability and iCPd, when using the nylon bag techniques. Based on the in vitro procedures, QTE increased the supply of N post-rumen; however, some evidence of a decreased fibre degradation were also observed. Therefore, the benefit of adding QTE to diets of cattle is still questionable.

In situ ruminal degradation characteristics of dry matter and crude protein from dried corn, high-protein corn, and wheat distillers grains

Background

The continuing growth of the ethanol industry has generated large amounts of various distillers grains co-products. These are characterized by a wide variation in chemical composition and ruminal degradability. Therefore, their precise formulation in the ruminant diet requires the systematic evaluation of their degradation profiles in the rumen.

Methods

Three distillers grains plus soluble co-products (DDGS) namely, corn DDGS, high-protein corn DDGS (HP-DDGS), and wheat DDGS, were subjected to an in situ trial to determine the degradation kinetics of the dry matter (DM) and crude protein (CP). Soybean meal (SBM), a feed with highly degradable protein in the rumen, was included as the fourth feed. The four feeds were incubated in duplicate at each time point in the rumen of three ruminally cannulated Hanwoo cattle for 1, 2, 4, 6, 8, 12, 24, and 48 h.

Results

Wheat DDGS had the highest filterable and soluble A fraction of its DM (37.2 %), but the lowest degradable B (49.5 %; P < 0.001) and an undegradable C fraction (13.3 %; P < 0.001). The filterable and soluble A fraction of CP was greatest with wheat DDGS, intermediate with corn DDGS, and lowest with HP-DDGS and SBM; however, the undegradable C fraction of CP was the greatest with HP-DDGS (41.2 %), intermediate with corn DDGS (2.7 %), and lowest with wheat DDGS and SMB (average 4.3 %). The degradation rate of degradable B fraction (% h⁻¹) was ranked from highest to lowest as follows for 1) DM: SBM (13.3), wheat DDGS (9.1), and corn DDGS and HP-DDGS (average 5.2); 2) CP: SBM (17.6), wheat DDGS (11.6), and corn DDGS and HP-DDGS (average 4.4). The in situ effective degradability of CP, assuming a passage rate of 0.06 h⁻¹, was the highest (P < 0.001) for SBM (73.9 %) and wheat DDGS (71.2 %), intermediate for corn DDGS (42.5 %), and the lowest for HP-DDGS (28.6 %), which suggests that corn DDGS and HP-DDGS are a good source of undegraded intake protein for ruminants.

Conclusions

This study provided a comparative estimate of ruminal DM and CP degradation characteristics for three DDGS co-products and SBM, which might be useful for their inclusion in the diet according to the ruminally undegraded to degraded intake protein ratio.

Estimation of utilisable crude protein at the duodenum of dried distillers' grains with solubles using a modified gas test

The objective of this study was to characterise the variation of utilisable crude protein at the duodenum (uCP) of dried distillers' grains with solubles (DDGS) for ruminants using a modified gas test and to predict the uCP in DDGS based on chemical composition. Thirteen samples originating from wheat, maize, barley or blends of different substrates were studied. The in vitro uCP was estimated using the modified Hohenheim gas test (moHGT). Samples were incubated in rumen fluid for 8 h, 24 h and 48 h followed by ammonia distillation. The obtained values were compared to reference values of uCP (based on the contents of crude protein (CP), in situ undegraded CP and metabolisable energy). The reference and in vitro values of uCP were calculated according to passage rates of 2, 5 and 8%/h (i.e., uCP2, uCP5 and uCP8, respectively). The in vitro uCP8 ranged from 214 to 320 g/kg DM and reference values from 158 to 302 g/kg DM. The in vitro uCP2 was on average lower (by 7 g/kg DM) and in vitro uCP8 was higher (by 56 g/kg DM) than their respective reference values. The in vitro uCP5 and uCP8 were correlated with reference values and the correlations were improved with increasing passage rates. When the differences of uCP content between in vitro and reference values were related to CP fractions, they increased with increasing content of CP fraction A and decreasing content of CP fraction B3 for uCP8. The prediction of uCP values from chemical composition was not reliable. It was concluded that uCP can be predicted on the basis of the moHGT method and CP fractions. The accuracy of prediction improved upon the inclusion of CP fractions and neutral-detergent insoluble nitrogen. The present study revealed a significant variation in the uCP content of DDGS, which should be considered when formulating rations for dairy cows.