Rumen Undegradable Protein Content Research Articles

PSXI-28 Nitrogen Footprint Assessment of Korean Native Beef Cattle Farms: Uncertainty Analysis and Mitigation Scenarios

Abstract Nitrogen (N) lost during beef cattle production accompanies various environmental impacts and has become an increasing concern among agricultural stakeholders. The objective of this study was to quantify the N footprint (NF) of Hanwoo beef cattle production in Korea at the farm gate through a life cycle assessment methodology. Field surveys were conducted on 106 farms across nine provinces to evaluate the NF of Hanwoo beef farms. N losses were calculated using emission factors using the refined Intergovernmental Panel on Climate Change (IPCC) guideline and expressed as NF [g N lost/kg of live body weight (LBW)]. Uncertainty and sensitivity analyses were deployed to evaluate the precision of the results and to quantify the variability of the input data. The NF was averaged 132.8 (±61.9) g N/kg LBW. Volatilization was the greatest contributing factor, followed by leaching and denitrification, each representing 68.4, 21.4, and 10.1 percent of the NF, respectively. The uncertainty of the output data was found to be 46.6 percent and was highly associated with emission factors uncertainties. We simulated four feasible mitigation scenarios that are cost effective and do not penalize productivity, and evaluated their capacity for reducing NF of meat: dietary modifications to decrease animal N excretion rates by adjusting the CP and rumen undegradable protein content for steers and fattening cows (A), microorganism additives to reduce volatilization from housing and manure storages through processing excess ammonium to synthesize microbial protein (B), using manure as land fertilizer instead of synthetic fertilizers to decrease denitrification from rice cultivation, and leaching and volatilization from all field types(C), and distributing straw-derived biochar (10 to 20 ton/ha) to the field after fertilizer application to reduce losses from crop production (D).Combining these scenarios demonstrated the potential to reduce NF by 12.3 percent. Overall, our study provides a national metric that can be used to communicate the N uses impact of Korean beef production. The analyses indicate that more precise results could be achieved with future endeavors toward developing country-specific emission factors. Integrating all four scenarios was shown to be the most effective approach to reducing the NF of beef production.

Use of Heating Methods and Xylose to Increase Rumen Undegradable Protein of Alternative Protein Sources: 1) Peanut Meal

Peanut meal has an excellent total protein content but also has low rumen undegradable protein (RUP). High-performance ruminants have high RUP requirements. We aimed to evaluate the effects of processing peanut meal with an autoclave and conventional and microwave ovens, with and without using xylose on its ruminal kinetics degradation parameters and intestinal digestibility (ID). In situ studies were conducted to determine dry matter (DM) and crude protein (CP) rumen degradation kinetics. In vitro studies were conducted to evaluate intestinal digestibility (ID). The control treatment had a greater fraction A for DM and CP than peanut meals processed with an autoclave or conventional oven. The control had greater kd for CP compared with the microwave. The addition of xylose decreased fraction A, the degradation rate of fraction B (kd) and RUP, and increased the protein B fraction of autoclaved peanut meal. We observed a decrease in effective degradability (ED) and increased RUP for processed treatments in all experiments compared with the control. Processing methods did not affect the protein ID of autoclaved peanut meal compared to the control. An interaction between xylose and heating time was observed, where increasing heating time linearly reduced the ID of xylose-untreated treatments. Overall, these results suggest that the tested methods effectively increased the RUP content of peanut meal.

Performance, nutrient use, and methanogenesis of Nellore cattle on a continuous grazing system of Urochloa brizantha and fed supplement types varying on protein and energy sources

Supplementation of grazing cattle may improve forage utilization, methane emission and efficiency of nutrients use. This study aimed to evaluate the effect of different supllementation strategies on performance, metabolic parameters and methane emission in Nellore cattle reared on well-managed marandu palisadegrass (Urochloa brizantha cv Marandu) pastures. Three supplementation strategies consisted of protein and energy sources from traditional ingredients compared to a novel feedstuff: TS) Traditional supplement (protein-energy) composed of ground corn and soybean meal; ES) energy supplement composed of ground corn; and DS) Distiller's coproduct supplement (protein-energy) composed of ground corn and dried distiller grain (DDG). All supplements were offered at 0.3% of body weight (BW). Sixty-nine growing Nellore bulls [251 kg of body weight (BW) ± 13.0 kg] were randomly distributed according to initial BW in nine paddocks (twenty-three animals per treatment, three paddocks per treatment) to evaluate liveweight gain. From these, eighteen bulls (381.83 kg BW ± 16.15 kg) were selected for methane emission measurements (six animals per treatment) using sulfur hexafluoride tracer gas technique. Six rumen cannulated steers (289.5 kg BW ± 19.6 kg) across six paddocks (two per treatment) were used in an incomplete double Latin square design (3 treatments x 4 periods) to evaluate metabolic parameters. Statistical analyses were done using the Mixed Procedure in SAS and adopting significance level at 5%. It was hypothesized that the use of DS or ES, could increase the N use efficiency because of a higher rumen undegradable protein content, and more energy available for microbial synthesis in the rumen, respectively. Overall, there were no differences on animal performance, intake, nutrients digestibility, ruminal parameters, and microbial protein synthesis among treatments indicating that any of the supplemental sources could be utilized. Although, animals in DS had lower urine N excretion. The ES supplement increased methane yield (g/DMI) and the methane conversion factor Ym (% of gross energy intake) when compared to other treatments, but not methane production, which was similar among all treatments.

252 Effects of Increasing Urea in Corn Silage Diets and Duration of Ensiling on the Rumen Undegradable Protein Content of Corn Silage

Abstract Two experiments were conducted to evaluate the effects of increasing urea in a corn silage cattle diet and ensiling time (ET) impact on rumen undegradable crude protein (RUP) content of corn silage. In Exp. 1, ten ruminally- and duodenally cannulated heifers (body weight 265 ± 16 kg) were utilized in a 4 × 4 Latin square design and treatments were urea included at 0, 0.5, 1, or 1.5% of dietary dry matter (DM). In Exp. 2, corn silage samples were collected during feedout at 32-d intervals from the time of ensiling (d 0) to 160 d post-ensiling followed by separation in water to forage and grain components. Forage and grain samples were ruminally incubated in two steers to calculate RUP content of corn silage. In Exp. 1, DM intake increased linearly from 5.7 to 6.8 kg/d as urea inclusion increased (P < 0.001). Apparent total tract digestibility of DM and organic matter increased linearly from 55.8% to 60.8%, and 60.1% to 64.9%, respectively (P < 0.001). Total tract digestibility of neutral and acid detergent fiber increased linearly with increasing urea inclusion (P ≤ 0.004). In Exp. 2, the RUP content of the corn grain component decreased from 43.7% of CP at day 0 to 15.8% and 10.0% of CP after 32 and 96 d of ensiling, respectively (quadratic, P < 0.01). The RUP content of the forage averaged 19.3% of CP across ET ranging from 21.5 to 17.8% of CP (P ≥ 0.28). Estimated from the individual components, the RUP content of whole corn silage decreased from 32% to 17.1% of CP after 160 d in storage, a portion of which is digestible. Urea supplementation improved digestibility of corn silage diets and RUP content of corn silage decreased with storage time, primarily driven by changes in the corn grain component.

55 Rumen undegradable protein content of native range and sub irrigated meadow forages

Abstract The in situ mobile bag procedure was used to compare rumen undegradable protein (RUP) content and RUP digestibility of Nebraska Sandhills range and meadow diet samples. Meadow samples (n = 12) were from June, July and August of 2 years while range samples (n = 19) were from June, July, September and December of 6 years. Samples were collected using esophageally fistulated cows (samples from 2 cows composited per time point), freeze-dried, and ground through a 2 mm screen. For each sample, 1.25 g was weighed into 8 replicate 8×10 cm Dacron bags with 50-µm pore size. Rumen incubation time was based on estimated digestibility and passage rate. Following rumen incubation, analysis of neutral detergent insoluble N (NDIN) on one-half of the bags was used to calculate RUP content. Remaining bags were treated with pepsin/HCl solution (37 °C) and stirred for three hours before duodenal incubation. Analysis of NDIN after recovery from feces determined RUP digestibility. Data were analyzed using month as a fixed effect and year and experiment as random effects. In meadow samples, CP (15.0% of DM) was consistent across June, July, and August (P = 0.72). Range samples tended to differ in CP content (P = 0.11), with June, July and September being similar (8.15% of DM) while December was 6.01%. In meadow samples, RUP averaged 21.9% of CP while range samples averaged 26.7% of CP, with no differences due to month (P ≥ 0.32). Because CP content was changing in range samples, RUP as a % of DM tended (P = 0.14) to decrease in December (1.66) compared to June, July, and Sept (2.25). In meadow samples, RUP digestibility (%) declined from 74.7% in June to 61.4% in July and Aug (P = 0.07). RUP digestibility (%) averaged 43.9% for all range samples (P = 0.66).

The in vitro protein degradability of legume and sudan grass forage types and ensiled mixtures

This study examined the in vitro crude protein (CP) degradability of wilted, dried for hay and ensiled Medicago sativa, Trifolium pratense and Sorghum sudanense, as well as of ensiled legume-sudan grass mixtures. The rumen degradable protein (RDP) was estimated using the latest Cornell net carbohydrate and protein system (CNCPS v6.5) and with the Streptomyces griseus protease assay (48 h of incubation). Sudan grass forages were the lowest in moderately degradable CP and the highest in CP fraction C, while red clover showed the least values for the soluble true protein like alfalfa forages for slowly degradable protein bound in neutral detergent fibre (NDF). Ensiling of legume-sudan grass mixtures decreases N-NH3 content by 12.2 and 5.1% in comparison with alfalfa and red clover silages, respectively. The RDP values for sudan grass (fresh, wilted, hay) were lower by 7.2 to 7.9% or 10.4 to 15.7% (CNCPS or S. griseus procedure) and up to 0.8 or 5.3 to 9.7% in comparison with alfalfa and red clover, respectively. The reduction of protein degradability in ensiled legume-sudan grass mixtures was 5.5 or 6.1% and 1.5 or 3% compared to alfalfa and red clover silages, respectively. Due to higher rumen undegradable protein content, the sudan grass and legume-sudan grass mixtures may be efficiently used to improve the protein utilization in ruminant nutrition.

Supplementation with different non-fiber carbohydrate sources in dairy cow diets with high or low rumen-undegradable protein content

ABSTRACT The objective for this study was to evaluate the supplementation with different non-fibrous carbohydrate (NFC) sources for grazing dairy cows in diets with high or low concentrations of rumen undegradable protein (RUP). Twelve multiparous cows averaging 30kg/d of milk production and 45±23 days in milk in a 4x4 Latin square design with 2 × 2 factorial arrangement were used. The difference in NFC content of the diets was achieved using ground corn (GC) or dried citrus pulp (DCP). Dietary RUP was altered by the partial replacement of soybean meal (LRUP) by roasted whole soybean and corn gluten meal (HRUP). Greater dry matter intake (DMI) was observed in DCP treatments compared to GC treatments (19.2 and 17.7kg/day of DM, respectively). Milk fat concentration was lower for LRUP treatments (3.4%) when compared to HRUP (3.6%). The milk protein concentration was greater for GC treatments (2.9%) in relation to DCP treatments (2.8%). Lower milk ureic nitrogen was observed when DCP diets were fed compared to those with GC (17.8 and 21.2mg/dL, respectively). The use of DCP as CNF source increased dry matter intake as well as milk fat concentration, although no differences in milk production were observed for RUP level.

PSII-1 Evaluation of RUP content and digestibility of feeds from organic and conventional sources

Abstract The purpose of this study was to evaluate and compare 17 different feeds for in situ rumen undegradable protein content (RUPc) and digestibility (RUPd) with the main objective being a comparison of organic and conventional sources of feeds. Two steers fitted with rumen cannulas and two heifers with duodenal cannulas were utilized for this study. Feeds used were procured from both conventional and USDA certified organic sources. Conventional feeds included field peas (FP), fish meal (FM), soybean meal (SBM), and dehydrated alfalfa (DA). Organic feeds included field peas (FPO), fish meal (FMO), soybean meal (SBMO), and dehydrated alfalfa (DAO). Each sample was weighed into both 5×10 cm and 10×20 cm dacron bags. Bags were evenly distributed between steers and ruminally incubated for 16 hours, replicated over two days. The 5×10 cm bags were treated with pepsin/HCl solution, inserted into the duodenum of the heifers, and retrieved from the feces to measure RUPd. Bags were washed, oven dried overnight, and residues composited to determine RUPc and RUPd. No digestibility data were gathered from FM or FMO due to lack of residue from digestion. Statistical analysis was performed using the Glimmix procedure of SAS, with sample as the experimental unit. The RUPc of DAO was not different (P = 1.0) from DA; SBMO was 32.7% greater (P < 0.01) than SBM; FMO was 30.2% greater (P < 0.01) than FM; FPO were not different (P = 0.46) than FP. The RUPd of DAO was 26.3% greater (P < 0.01) than DA; no differences were observed between SBMO and SBM or FPO and FP (P > 0.98). These data indicate that there may be some differences in rumen undegradable protein content and digestibility between conventional and certified organic feeds when measured in situ.

334 Evaluation of sources of RUP fed to Holstein steers in a simulated organic beef production system

Abstract This study evaluated rumen undegradable protein (RUP) sources on performance of lightweight Holstein steers fed diets that simulated the requirements for organic beef production. Holstein steers (n = 59; initial BW = 213kg) were fed individually for 214 d. Diets contained 30% alfalfa haylage, 5% supplement to meet mineral requirements, and differing proportions of dry rolled corn and a protein source to supply RUP. Steers were assigned randomly to dietary treatments: a protein-deficient control (CON), field peas (FP), field peas and fish meal (FPFM), soybean meal (SBM), and a soybean meal treated to increase RUP (Soypass; SP). Diets were reformulated by phase as MP requirements decreased. Experimental design was completely randomized with experimental unit being steer. A tendency (P = 0.09) for a difference in ADG in the first phase was observed, with steers fed any RUP source having greater ADG than CON. No difference (P ≥ 0.22) was detected for ADG in subsequent phases as RUP sources were displaced with corn. Intakes were not different (P ≥ 0.26) among treatments during the first and last phase, but during phase two and three calves fed SP had greater DMI (P ≤ 0.03) compared with FP or FPFM, with the CON and SBM groups being intermediate. In the first phase, calves in the CON group had significantly (P < 0.01) lower G:F compared to treatments with RUP, which were not different from one another. No differences (P ≥ 0.31) were observed between treatments for G:F during the final three phases. These data suggest that supplementing RUP improved ADG and G:F, but source of RUP did not impact performance of lightweight Holstein steers when inclusions were varied to account for differences in RUP content of each protein source. These animals compensated for a deficiency in MP early in the feeding period.

Protein fractions as influenced by cultivars, stage of maturity and cutting dates in alfalfa (Medicago sativa L.)

This study was undertaken to determine the relationship between CNCPS (Cornell Net Carbohydrate and Protein System) protein fractions and in vitro RUP (Rumen Undegradable Protein) concentration and the variability of protein fractions among alfalfa cultivars grown in Serbia. Two cultivars of alfalfa (Medicago sativa L.) – Serbian cv K 28 and American cv G + 13R + CZ were sampled at three stages of maturity. Comparing the two cultivars of alfalfa (K 28 vs. G + 13R + CZ) means, there were significant differences in all protein fractions. Two investigated alfalfa cultivars differed significantly (p less than 0.01) in RUP content, cv G + 13R + CZ was higher in RUP than cv K 28. Stage of maturity had an effect on proportions of the protein fractions. From a nutritional and breeding point of view, cultivar such as G + 13R + CZ is desirable because it combine higher CP (Crude Protein) values with lower protein degradability than cv K 28.

Corn silage rumen undegradable protein content and response of growing calves to rumen undegradable protein supplement.

The amount of rumen undegradable protein (RUP) in corn silage and the extent to which it is digested in the small intestine are uncertain. Three studies were conducted to determine RUP content of corn silage, and the effects of supplementing increasing concentrations of RUP on the growing performance of calves fed a corn silage diet. Experiments 1 and 2 used in situ methods to evaluate the RUP content of corn silage. In experiment 1, corn silages harvested at 37% or 42% dry matter (DM) were compared. In experiment 2, dry-rolled corn (89.4% DM) was reconstituted to 75%, 70%, 65%, and 50% DM and ensiled in mini-silos (2,265 cm3) for 30, 90, 180, or 270 d to simulate the corn grain within corn silage, dry-rolled corn is more mature than corn grain harvested in corn silage. Experiment 3 used 60 steers (275 kg initial body weight, SD = 18) in an 83-d growing study to evaluate the effects of supplementing 0.4%, 1.7%, 3.0%, 4.2%, or 5.5% RUP (% of diet DM) on performance. In experiment 1, RUP as a % of DM was not different between the two corn silages (P ≥ 0.12), averaging 0.59% for samples refluxed in a neutral detergent solution (NDS) and 1.8% for samples not refluxed in NDS. Dry matter digestibility (DMD) also did not differ (P ≥ 0.19), averaging 67.4%. In experiment 2, as moisture content of the corn grain increased, DMD increased linearly (P < 0.01) and RUP content decreased linearly (P < 0.01). The DMD increased quadratically (P = 0.02), whereas RUP content decreased linearly (P < 0.01) as days of ensiling increased. In experiment 3, there were no differences in DM intake (DMI; P ≥ 0.33) among treatments for period 1 (d 1 to 37). However, average daily gain (ADG) and gain-to-feed ratio (G:F) both linearly increased (P < 0.01) as RUP supplement inclusion increased. There were no differences in DMI (P ≥ 0.16), ADG (P ≥ 0.11), or G:F (P ≥ 0.64) in period 2 (d 38 to 83). For the overall growing period (d 1 to 83), a linear increase was observed for ending body weight (P = 0.01), ADG (P < 0.01), and G:F (P < 0.01) as RUP supplement inclusion increased from 0.4% to 5.5% of diet DM. The RUP content of corn silage is lower than previously reported. Data collected suggest the crude protein within corn silage is 13% RUP, and approximately 1/2 is digestible. The moisture content of corn silage at the time of harvest and the amount of time corn silage is stored continually impact protein availability. Supplementing growing calves fed corn silage with RUP will improve performance.

Detect molecular spectral features of newly developed Vicia faba varieties and protein metabolic characteristics in ruminant system using advanced synchrotron radiation based infrared microspectroscopy: A preliminary study.

Recently, advanced synchrotron radiation-based Fourier transform infrared microspectroscopy (SR-IMS) has been developed as a rapid, direct, non-destructive and bioanalytical technique. To date, there has been very little application of this technique to study the molecular structure make-up in pulse seeds. Thus, the objectives of this study were to detect the interactive association between protein molecular structure and nutrient availability of newly developed Vicia faba varieties. Two different varieties of faba beans (CDC Snowdrop = low-tannin variety; vs. FB9-4 = high-tannin variety) were selected for this study. The molecular spectra data were collected by using SR-IMS. The ratio of both amide I to II area and height were higher (P < 0.01), while the ratio of α-helix to β-sheet was lower (P < 0.05) in CDC Snowdrop compared to FB9-4. The crude protein (CP) content and the predicted truly digestible nutrients as well as the bioenergy values did not vary between two varieties. The CDC Snowdrop had exhibited a higher (P < 0.01) rapidly degradable CP fraction (75.99 vs. 71.45% on CP) and a lower (P < 0.01) moderately degradable CP fraction (19.43 vs. 22.85% on CP), resulting in a higher (P < 0.01) rumen degradable protein and a lower (P < 0.01) rumen undegradable protein content than that of FB9-4 variety. However, the total supply of digestible rumen undegraded feed protein was higher (P < 0.05) in FB9-4 than CDC Snowdrop. Strong positive correlations were found between the ratio of α-helix to β-sheet and CP contents (R = 0.86, P < 0.01) as well as the truly digestible CP contents (R = 0.83, P < 0.01); respectively. In conclusion, the results of this study reveal that the protein are metabolized differently between different type of faba bean varieties and the advanced SR-IMS molecular spectroscopy can be used to rapidly delineate protein molecular structure motifs along with their nutritive value in ruminant livestock system.

Effects of rumen-undegradable protein on intake, performance, and mammary gland development in prepubertal and pubertal dairy heifers

The objective of this study was to evaluate the influence of different amounts of rumen-undegradable protein (RUP) on intake, N balance, performance, mammary gland development, carcass traits, and hormonal status of Holstein heifers at different physiological stages (PS). Sixteen prepubertal (PRE) heifers (initial BW = 106 ± 7.6 kg; age = 4.3 ± 0.46 mo) and 16 pubertal (PUB) heifers (initial BW = 224 ± 7.9 kg; age = 12.6 ± 0.45 mo) were used in an experiment over a period of 84 d. Four diets with increasing RUP contents (38, 44, 51, and 57% of dietary crude protein) and heifers at 2 PS (PRE or PUB) were used in a 4 × 2 factorial arrangement of treatments in a completely randomized design. Throughout the experiment, 2 digestibility trials were performed over 5 consecutive days (starting at d 36 and 78) involving feed and ort sampling and spot collections of feces and urine. At d 0 and 83, body ultrasound images were obtained for real-time carcass trait evaluation. The mammary gland was ultrasonically scanned at d 0 and every 3 wk during the experiment. Blood samples were taken at d 0 and 84 to determine serum concentrations of progesterone, estrogen, insulin-like growth factor I (IGF-I), and insulin. No interaction between PS and the level of RUP was found for any trait. Apparent digestibility of dry matter, organic matter, and neutral detergent fiber corrected for ash and protein was not affected by RUP level but was lower for PRE compared with PUB heifers. Sorting against neutral detergent fiber corrected for ash and protein (tendency only) and for crude protein was greater for PUB than PRE heifers. Pubertal heifers had greater average daily gain (905 vs. 505 g/d) and N retention (25.9 vs. 12.5 g/d) than PRE heifers. In addition, average daily gain and N retention were greatest at 51% RUP of dietary protein. Mammary ultrasonography indicated no effects of RUP amounts on mammary gland composition, whereas PRE heifers had greater pixel values than PUB, indicating higher contents of fat rather than protein in the mammary glands of PRE heifers. Serum progesterone and IGF-I concentration was affected only by PS, and PRE heifers had greater values of progesterone and IGF-I concentrations than PUB heifers. Serum insulin concentration was unaffected by PS but tended to be higher at 51% of RUP. In conclusion, an RUP level of 51% increases body weight, average daily gain, feed efficiency, and N retention in heifers regardless of the PS. In addition, PRE heifers have a lower sorting ability and reduced intake, total-tract digestibility, and N retention. They also have higher amounts of fat in their mammary glands, even at moderate growth rates.

Effects of replacing soybean meal with canola meal differing in rumen-undegradable protein content on ruminal fermentation and gas production kinetics using 2 in vitro systems

Previous research indicated that there were significant differences in rumen-undegradable protein (RUP) among canola meals (CM), which could influence the nutritional value of CM. The objectives of this study were to (1) evaluate the effects of feeding CM with different RUP contents on ruminal fermentation, nutrient digestion, and microbial growth using a dual-flow continuous culture system (experiment 1) and (2) evaluate ruminal gas production kinetics, in vitro organic matter (OM) digestibility, and methane (CH4) production of soybean meal (SBM) and CM with low or high RUP in the diet or as a sole ingredient using a gas production system (experiments 2 and 3). In experiment 1, diets were randomly assigned to 6 fermentors in a replicated 3 × 3 Latin square. The only ingredient that differed among diets was the protein supplement. The treatments were (1) solvent-extracted SBM, (2) low-RUP solvent-extracted CM (38% RUP as a percentage of crude protein), and (3) high-RUP solvent-extracted CM (50% RUP). Diets were prepared as 3 concentrate mixtures that were combined with 25% orchardgrass hay and 15% wheat straw (dry matter basis). Experiments 2 and 3 had the same design with 24 bottles incubated 3 times for 48 h each. During the 48-h incubation, the cumulative pressure was recorded to determine gas production kinetics, in vitro OM digestibility, and CH4 production. In experiment 1, N flow (g/d), efficiency of N use, efficiency of bacterial N synthesis, total volatile fatty acids (mM), and molar proportion of acetate, propionate, and isobutyrate were not affected by treatments. There were tendencies for a decrease in ruminal NH3-N and an increase in molar proportion of butyrate for the SBM diet compared with both CM diets. The molar proportion of valerate was greater in both CM diets, whereas the molar proportion of isovalerate and total branched-chain volatile fatty acids was lower for the CM diets compared with the SBM diet. In experiments 2 and 3, the SBM diet had a greater gas pool size than both CM diets. The SBM diet increased in vitro OM digestibility; however, it also tended to increase CH4 production (mM and g/kg of DM) compared with both CM diets. Based on the results of this study, CM with RUP varying from 38 to 50% of crude protein does not affect ruminal fermentation, nutrient digestion, and microbial growth when CM is included at up to 34% of the diet.

Effects of temperature, heating time and particle size on values of rumen undegradable protein of roasted soybean

Roasted soybeans are commonly used in diets for dairy cows, but the processing conditions of roasted soybean and their effects on rumen undegradable protein (RUP) have not been fully understood. In this study, the effect of the processing of roasted soybean on RUP was examined through a factorial arrangement of treatments. The effects of roasting temperature (115 oC, 130 oC and 145 oC), time of roasting (5, 10 and 15 min) and particle size of soybean (whole, coarse and fine) on the protein fractions of roasted soybean were analysed with the Cornell Net Carbohydrate and Protein System (CNCPS) and protein dispersibility index (PDI) methods. The whole, coarsely ground and finely ground soybean had mean particle sizes of 5.30 mm, 1.15 mm and 1.05 mm. The proportion of soluble protein was reduced with increasing temperature and time of roasting. The true protein with intermediate rates of degradation decreased with escalating temperatures, but increased when the time was raised and the particle size reduced. Also, the true protein level with slow rates of degradation was raised with increasing temperature and heating time, but reduced when decreasing the particle size. The undegradable true protein level, on the other hand, was increased by decreasing the particle size. The results of CNCPS and PDI revealed that the recommended method would be to use soybeans with a particle size of 1.15 mm, and to roast them at 115 oC for 10 minutes. Furthermore, the results showed that different methods of processing used in soybean roasting could strongly affect RUP content. Keywords: Processing, roasted soybean grain, rumen undegradable protein

에너지 및 반추위 미분해단백질 수준을 달리한 사료급여가 비유중기 유우에 미치는 영향

Sources of energy and rumen undegradable protein (RUP) have been used to meet nutrient requirements for high producing dairy cows. However studies for manipulation the levels of energy and RUP in diets have been mainly achieved using dairy cows at early-lactation period. The objective of this study thus, was to investigate the effects of different energy and rumen undegradable protein (RUP) levels on dry matter intake and milk yield in Holstein cows at mid-lactation period. Basal diet was prepared as TMR to meet nutrient requirements for dairy cows at mid-lactation according to NRC recommendation. Cows of control group (Con) were fed only basal diets while ground corn (0.5 kg/d), heat-treated soybean meal (0.5 kg/d), and their mixture (0.25 kg of each supplements/d) were added to diets for cows of treatment groups (T1, T2, and T3 respectively) to modulate the level of energy and RUP contents in diets. Addition of energy or RUP source in basal TMR did not affect in total DMI while TMR intake tended to be higher in Con compared to T3. Cows fed T3 diets tended to show increased milk yield and MUN content than those of Con. Cows for T2 as well as T3 had lower ADG (P<0.05) compared with those of Con. We concluded that the addition of RUP source in diets for dairy cows on mid-lactation period might cause the decrement of DMI and ADG.

The effect of cultivar on the changes in protein quality during wilting and ensiling of red clover (Trifolium pratense L.)

SUMMARYRed clover (Trifolium pratense L.) silage usually contains lower contents of non-protein nitrogen (NPN) compared with other forage legumes. This is often attributed to the polyphenol oxidase (PPO) activity in red clover, although in most field studies the PPO activity was not measured. Therefore, a laboratory ensiling experiment with three red clover cultivars and one white clover cultivar as control grown in two management systems (with and without mechanical stress) over 2 consecutive years was conducted. Fresh, wilted and ensiled clover herbage was sampled at four cutting dates per year to determine the crude protein (CP) fractions according to the Cornell Net Carbohydrate and Protein System. The specific PPO activity was measured photometrically in fresh clover leaves. The content of CP fraction A (NPN) increased from fresh over wilted to ensiled clover herbage at the expense of the content of CP fraction B (true protein), irrespective of species, cultivar and year. The most important source of variation for all CP fractions and the calculated rumen-undegradable protein contents was generally the herbage condition, except for CP fraction C (unavailable protein). White clover silage consisted of higher contents of CP fraction A and lower contents of CP fraction B3 in CP compared with red clover silage. As a result, the calculated rumen-undegradable protein content of white clover silage was lower than that of all red clover cultivars. In conclusion, the extent of proteolysis during ensiling among the silages made from the herbage of different red clover cultivars was primarily influenced by the stage of maturity at harvesting and the degree of wilting at ensiling. The variation in specific PPO activity could not be related to the extent of proteolysis.

Effect of quantifying peptide release on ruminal protein degradation determined using the inhibitor in vitro system

The aim of this work was to compare use of an o-phthaldialdehyde (OPA) colorimetric assay (OPA-C), which responds to both free AA and peptides, with an OPA fluorimetric assay (OPA-F), which is insensitive to peptides, to quantify rates of ruminal protein degradation in the inhibitor in vitro system using Michaelis-Menten saturation kinetics. Four protein concentrates (expeller-extracted soybean meal, ESBM; 2 solvent-extracted soybean meals, SSBM1 and SSBM2; and casein) were incubated in a ruminal in vitro system treated with hydrazine and chloramphenicol to inhibit microbial uptake of protein degradation products. Proteins were weighed to give a range of N concentrations (from 0.15 to 3mg of N/mL of inoculum) and incubated with 10mL of ruminal inoculum and 5mL of buffer; fermentations were stopped after 2h by adding trichloroacetic acid (TCA). Proteins were analyzed for buffer-soluble N and buffer extracts were treated with TCA to determine N degraded at t=0 (FD0). The TCA supernatants were analyzed for ammonia (phenol-hypochlorite assay), total AA (TAA; OPA-F), and TAA plus oligopeptides (OPA-C) by flow injection analysis. Velocity of protein degradation was computed from extent of release of 1) ammonia plus free TAA or 2) ammonia plus free TAA and peptides. Rate of degradation (kd) was quantified using nonlinear regression of the integrated Michaelis-Menten equation. The parameters Km (Michaelis constant) and kd (Vmax/Km), where Vmax=maximum velocity, were estimated directly; kd values were adjusted (Akd) for the fraction FD0 using the equation Akd=kd − FD0/2. The OPA-C assay yielded faster degradation rates due to the contribution of peptides to the fraction degraded (overall mean=0.280/h by OPA-C and 0.219/h by OPA-F). Degradation rates for SSBM samples (0.231/h and 0.181/h) and ESBM (0.086/h) obtained by the OPA-C assay were more rapid than rates reported by the National Research Council (NRC). Both assays indicated that the 2 SSBM differed in rumen-undegradable protein (RUP) content; the more slowly degraded SSBM had RUP content (35% by OPA-C) similar to that reported by the NRC. The RUP content of ESBM (42% by OPA-C) was lower than the NRC value. Preliminary studies with 4 additional protein concentrates confirmed that accounting for peptide formation increased degradation rate; however, a trend for an interaction between assay and protein source suggested that peptide release made a smaller contribution to rate for more slowly degraded proteins. The OPA-C assay is a simple and reliable method to quantify formation of small peptides.

Response to Increased Rumen Undegradable Protein Intake by Lactating Dairy Cows

A dataset was constructed from literature published between 1988 and 2000 to determine whether increased intake of rumen undegradable protein (RUP) was related to increased milk and milk component production. The dataset represented 436 treatment means from 77 published reports. Nutrient intakes were calculated using tabular values for nutrient contents of individual feeds. There was no relationship between RUP content of diets and milk production, unless RUP content of feeds was adjusted to reflect differences in DMI. Increased intake of RUP was associated with increased yield of milk, 4% fat-corrected milk (FCM), and energy-corrected milk (ECM). Using new systems to adjust intake of rumen undegradable intake protein for diet and DMI effects resulted in marginal improvement to the relationships when compared with the use of tabular values for the RUP content of feeds. Within the dataset, a 526-g increase in RUP intake at constant DMI was required to produce a 1-kg increase in milk. Further improvement in predicting milk production response to undegradable protein intake will require investigation of other factors such as amino acid flow, specific attributes of feeds, and/or stage of lactation.

Development of a System to Predict Feed Protein Flow to the Small Intestine of Cattle

A data set constructed from research trials published between 1979 and 1998 was used to derive equations to adjust published tabular values for the rumen-undegradable protein (RUP) content of feeds to better predict the passage of nonammonia nonmicrobial N (NANMN) to the small intestine of lactating dairy cows. Both linear and nonlinear forms of equations were considered for making adjustments. Iterative processes were used to estimate equation parameters. A logistic equation was developed and considered to be the most optimal for adjustment of published tabular RUP contents of feeds. The equation is a function of dietary dry matter intake (DMI) and includes terms for tabular RUP and nonprotein N contents of individual feeds. The equation has a standard error of prediction of 69.29g of NANMN/ d per cow and a root mean square prediction error of 104.63g of NANMN/d per cow. Independent evaluation of the equation indicated that the concept of variable RUP content for feeds based on DMI is correct. Further refinements may be needed as other data become available to quantify the effects of additional factors on the RUP value of feeds.