Amount Of Rumen Degradable Protein Research Articles

Quantifying the ruminal degradation of nutrients in three cultivars of perennial ryegrass (Lolium perenne L.) sampled during early spring and summer

Context The Australian dairy industry is characterised by pasture-based feeding systems, where grazed pasture is commonly supplemented with cereal grain to increase milk production of dairy cows. Perennial ryegrass (PRG; Lolium perenne L.) is the most commonly used pasture species, with a wide range of cultivars available. However, the nutritive characteristics and the degradation of nutrients in individual PRG cultivars grown in different environments in Australia are unknown, and significant variation between cultivars may impact on supplementary nutrient requirements. Aims The objective of this experiment was to quantify the extent of ruminal degradation of nutrients in three contrasting PRG cultivars (Bealey NEA2, Trojan NEA2 and Victorian SE) harvested during early spring and summer from Gippsland, northern Victoria and south-west Victoria in Victoria, Australia. Methods Degradation parameters were determined by in situ incubation in the rumens of non-lactating, rumen-fistulated Holstein–Friesian cows for 72 h using a nylon bag technique. Key results During both seasons, Bealey NEA2 had the greatest effective degradability of crude protein and neutral detergent fibre compared with Trojan NEA2 and Victorian SE. Cultivars harvested during early spring had greater effective degradability of crude protein and neutral detergent fibre, and a greater amount of rumen degradable protein compared with cultivars harvested during summer. Cultivars harvested from Gippsland had greater crude protein and neutral detergent fibre effective degradability, as well as a greater amount of rumen degradable protein, whereas cultivars harvested from northern Victoria had a greater amount of undegraded dietary protein. Conclusions These results demonstrate that the ruminal degradation of PRG cultivars declines with increasing maturity, and that there are differences between cultivars and regions; however, differences between seasons are of a greater magnitude and are more important to consider when formulating optimal supplementary grain rations. Implications This research has positive implications for farmers who will be able to understand the degradation of nutrients in PRG, and the amounts of rumen degradable protein and undegraded dietary protein available from pasture during each season. Farmers will be able to use this information to formulate supplementary grain rations that complement the nutrients from pasture and optimise milk production.

Ruminal and intestinal protein degradability of various seaweed species measured in situ in dairy cows

The use of seaweeds in animal diets is not new. However, little is known about the feed value of seaweed, both in terms of chemical composition and protein digestibility, and regarding variation between species and season. In this study, eight seaweed species of the genus Acrosiphonia, Alaria, Laminaria, Mastocarpus, Palmaria, Pelvetia, Porphyra, and Ulva were sampled in spring (March) and autumn (October and November) 2014 at the coast of Bodø in Northern Norway, and were analysed for chemical composition, in situ rumen degradability and total tract crude protein (CP) digestibility. Ash content in dry matter (DM) was generally high (overall mean 190g/kg in DM) and varied considerably, between species (P<0.01) and between seasons (P=0.02). CP concentration in DM varied both between species (P<0.0001) and seasons (P<0.01). Highest CP in DM was found for Porphyra (350g/kg DM) and lowest for Pelvetia (90g/kg DM). Spring samples were higher in CP than autumn samples. The effective degradability estimated at 5% rumen passage rate (ED5) of CP varied between species (P<0.0001) but not between seasons (P=0.10). The highest ED5 of CP was found for Alaria (550g/kg CP) and lowest for Ulva (240g/kg CP). Digestible rumen escape protein (DEP) varied significantly between species (P<0.0001) but not between seasons (P=0.06); highest DEP was found for Ulva (530g/kg CP) and Porphyra (500g/kg CP). Based on our results, Acrosiphonia, Alaria, Laminaria, Mastocarpus and Palmaria can supply the rumen with high amounts of rumen degradable protein, while Porphyra and Ulva can be used as a source of digestible bypass protein. Pelvetia had a very low degradability and should not be used to feed dairy cows.

In situ ruminal degradation characteristics of by-product feedstuffs for beef cattle consuming low-quality forage1

Eight ruminally cannulated steers (BW = 753 +/- 48 kg) were used to evaluate in situ N, NDF, and DM degradation characteristics of by-product feeds and their application for beef cows consuming low-quality forage. Experimental feedstuffs included (DM basis) 1) extruded-expelled cottonseed meal (ECSM; 33% CP and 55% NDF), 2) extruded-expelled cottonseed meal with linters (ECSML; 25% CP and 41% NDF), 3) dried distillers grains with solubles (DGS; 33% CP and 36% NDF), 4) solvent-extracted cottonseed meal (CSM; 43% CP and 29% NDF), and 5) a blend of 76% wheat middlings with 18% CSM (WMCSM; 23% CP and 40% NDF). Steers were fed chopped prairie hay (4.8% CP, 69% NDF; DM basis) ad libitum and received 0.38 kg/100 kg of BW of WMCSM daily. In situ degradation kinetics of N, NDF, and DM components included the following fractions: A (immediately soluble), B (potentially degradable), and C (undegradable). Calculated rumen degradable protein (RDP) for ECSM was the greatest among all feedstuffs (83.8%; P < 0.01), which was composed of a large A fraction of N (41%). Similar RDP values were observed for DGS and ECSML (50.7 and 50.9%, respectively, P = 0.93). The B fraction N for ECSML was large (88.9%); however, most of this was unavailable for ruminal degradation. The amount of RDP in CSM and WMCSM was similar (78.2 and 73.5%, respectively; P = 0.12) though the A fraction of N was greater for WMCSM compared with CSM (P < 0.01). Degradability of NDF was greatest (P < 0.01) for DGS (67.4%) and was similar (P = 0.48) for WMCSM and CSM (54.5 and 57.0%, respectively). The least degradability of NDF was calculated for ECSM (29.3%; P < 0.01), attributed to greater lignin content (13.3%, DM). Degradability of DM was greatest (P < 0.01) for CSM and WMCSM (63.7 and 59.4%, respectively) and least (P < 0.01) for ECSM (36.5%) and ECSML (40.6%). Ruminal N degradation characteristics of ECSM were similar to more traditional supplements containing CSM and WMCSM. The RDP for ECSML and DGS N was less compared with other feedstuffs, indicating these feeds may need to be blended with other ingredients containing greater concentrations of degradable N, particularly in situations in which forage RDP is low.

Stochastic simulation of rumen degradable protein surplus in grazing dairy cows

In grazing systems, the quality of the pasture is an ever-changing scenario: weather, forage variety, level of fertilisation and age of the plant are some of many factors influencing the quality of the cows’ diet. Furthermore, accurate dry matter intake measurements are difficult to obtain under grazing conditions. As a result, the use of mathematical models to describe aspects of pasture digestion has been limited in practice. Stochastic modelling might overcome this limitation. In the current example, a static model of cow digestion (National Research Council (NRC), 2001. Nutrient Requirements of Dairy Cattle. National Academy Press, Washington, DC, USA) was coded into a software package for probabilistic simulation (GoldSim v. 9.2) using stochastic variables for pasture chemical composition and dry matter intake. Partitioning of crude protein (nitrogen) in the rumen of cows was simulated over a period of 7 weeks in early spring to estimate the potential losses of nitrogen due to high ruminal degradability of protein when different levels and types of supplementary feeds were offered. More than 98% of the simulations resulted in estimated excess of rumen degradable protein of up to 561 g N/d. By comparison, the magnitude of deficit was small (up to −42 g N/d) in the simulations with negative values for rumen degradable protein balance. Pasture crude protein concentration was the stochastic variable with the biggest influence on the amount of rumen degradable protein. Higher levels of supplementation (60 g DM supplements per 100 g DMI) resulted in estimated excess rumen degradable protein that was 0.3 of that obtained from simulations with lower levels of supplementation (35 g DM supplements per 100 g DMI). Stochastic simulation may be useful to explore the likelihood of responses to management scenarios designed to increase the efficiency of dietary nitrogen utilisation in pastoral systems characterised by uncertainty and variability.

Protein Level for Alfalfa and Corn Silage-Based Diets: II. Nitrogen Balance and Manure Characteristics

This N balance study was completed with 48 multiparous Holstein cows (body weight [BW]=653kg; days in milk=89) blocked by calving date and assigned to a 2×2 factorial arrangement of dietary treatments. The total mixed ration included alfalfa silage (AS) or corn silage (CS) as the primary forage source (41 and 14% vs. 14 and 41% of diet dry matter (DM), respectively) and were formulated for recommended (RP) or excessive (HP) amounts of rumen degradable protein (RDP) and rumen undegradable protein (RUP) according to the guidelines of the National Research Council (NRC). Crude protein (CP) averaged 16.5, 18.0, 16.4, and 17.3% for the AS-RP; AS-HP; CS-RP; and CS-HP diet, respectively (DM basis). Regardless of primary forage source, the reduction in dietary CP to the NRC guidelines tended to improve milk yield (43.4 vs. 41.0kg/d) but did not alter 3.5% fat-corrected milk (37.0kg/d) or milk true protein yield (1167g/d). In this trial, cows fed the CS-based diets consumed less DM than those fed the AS-based diets in part because of rumen acidosis. The adverse effect of low rumen pH was accompanied by an increase in urinary N (UN) as a percentage of N intake, but did not alter milk yield. Notwithstanding partial confounding, fecal N (FN) was 49g/d lower (213 vs. 164g/d), UN was unchanged (229g/d), but milk N tended to be higher (194 vs. 206g/d) when cows were fed the CS-based diets compared with AS-based diets. Compared with the HP diets, cows fed the RP diets had similar FN (189g/d) and milk N (200g/d), but UN and urine urea N were reduced by 41g/d (249 vs. 208g/d) and 40g/d (210 vs. 171g/d), respectively. Fecal N concentration was higher for CS-based diets, but urinary N concentration was higher for AS-based diets. The reduction in dietary CP did not influence these concentrations but lowered urine volume. The metabolic relationships between energy and protein in determining the fate of excess dietary N (primarily in the form of excess RUP in this trial) was illustrated by a 17% increase in the UN to FN ratio for cows fed AS-HP compared with the AS-RP diet and a 42% increase in the UN to FN ratio for CS-HP compared with CS-RP diet, when cows’ energy status was compromised because of rumen acidosis. In this trial, UN ranged from 150 to 320g/d, and was best predicted as UN (g/d)=0.0283×BW (kg)×milk urea N (mg/dL). The NRC protein guidelines should not be exceeded to avoid unnecessary losses of manure N and, in particular, urine urea N.

Protein Level for Alfalfa and Corn Silage-Based Diets: I. Lactational Response and Milk Urea Nitrogen

This study was designed to evaluate lactational responses of cows fed corn silage (CS) or alfalfa silage (AS) as primary forage source when the diet was balanced for recommended (RP) or excessive (HP) amounts of rumen degradable protein (RDP) and undegradable protein (RUP) according to the recommendations of the National Research Council (NRC). A second objective was to evaluate different sources of variations in milk urea N (MUN). The total mixed rations included 55% forage on a dry matter (DM) basis as either 14% CS and 41% AS or 14% AS and 41% CS. Diets were offered to 48 multiparous Holstein cows (body weight = 652kg) that were assigned randomly to treatments arranged as a 2×2 factorial in 12 complete blocks based on calving date. Data collected during wk 4 to 12 of lactation were adjusted to those obtained from a pretreatment diet fed during wk 1 to 3. Crude protein (CP) averaged 16.5, 18.0, 16.2, and 17.1% of DM in the AS-RP; AS-HP; CS-RP; and CS-HP diets, respectively. Overall DM intake (DMI) was 1.5kg/d lower than predicted by NRC (24.6 vs. 26.1kg/d), but 3.5% fat-corrected milk (FCM) was higher than expected (46.1 vs. 45.0kg/d). The responses to a reduction in dietary protein were independent of primary forage source, except for milk true protein (TP) percentage. Primary forage source did not influence DMI, 3.5% FCM, TP yield, or MUN. However, compared with the AS-based diets, cows fed CS-based diets produced more milk (49.0 vs. 46.4kg/d), less fat (3.07% vs. 3.54% and 1500 vs. 1651g/d), and tended to gain more body weight. There were no benefits to feeding diets above NRC protein recommendations, regardless of forage source. Reducing CP from 17.5 to 16.4% of diet DM did not alter milk yield (47.7kg/d) or milk TP yield (1293g/d), but lowered N intake by 65g/d (700 vs. 635g/d) and lowered MUN by 1unit (12.7 vs. 11.7mg/dL). A positive correlation between MUN and production efficiency (3.5% FCM/DMI) on wk 3 of lactation suggested that body protein mobilization might impact MUN in early lactation. The correlation between MUN and DMI tended to be negative in wk 3, but was positive in wk 6 to 12 of lactation. The same was true for the correlation between MUN and somatic cell score. Regression analysis of the postpeak lactation data of this study indicated that the expected MUN was essentially 12mg/dL when NRC-predicted RDP and RUP balances were 0g/d, with a linear deviation of 0.1 and 0.03mg/dL per 10g of change in RDP and RUP balance, respectively.

Effect of amount of rumen degradable protein on the utilization of wheat straw by Dohne Merino wethers

AbstractA 5 ✕ 5 Latin square was conducted with ruminally and duodenally cannulated Dohne Merino wethers consuming wheat straw to determine the effect of different rumen degradable protein (RDP) levels on forage intake, fermentation characteristics, nutrient flow and digestion. The wethers had ad libitum access to water and wheat straw (32 g crude protein (CP) per kg dry matter (DM); 742 g neutral-detergent fibre (NDF) per kg DM) that was offered twice daily, immediately after intraruminal infusion of the supplements at 07:00 and 19:00 h. The supplemental RDP (calcium caseinate; 900 g CP per kg DM) levels were: 0, 40, 80, 120 and 160 g/day. Each period consisted of 14 days of adaptation and 6 days of sampling. Forage and total organic matter (OM) intakes increased in a linear manner (P &lt; 0•01) with increasing supplemental RDP levels. Digestible organic matter intake (DOMI) displayed a quadratic increase with elevated amounts of RDP (P &lt; 0•01). The effects of treatments on rumen and total tract digestion, as well as fluid dilution rate were minimal. Microbial nitrogen (MN) flow to the duodenum and microbial efficiency increased quadratically (P &lt; 0•04) with increased RDP supplementation. Rumen ammonia nitrogen (NH3-N) concentrations increased linearly (P &lt; 0•01) and total volatile fatty acids (VFA) tended to increase linearly (P = 0•07). In conclusion, RDP supplementation to Dohne Merino wethers consuming wheat straw generally enhanced rumen fermentation and forage intake. A total RDP intake (sources: calcium caseinate and wheat straw) of 3•30 g/kg M0•75 or 0•12 of DOM maximized DOMI.

The effects of excess rumen degradable protein in ewes on ovulation rate, fertilization and embryo survival in vivo and during in vitro culture.

In a review of the effects of protein nutrition on reproduction in dairy cattle, Ferguson and Chalupa (1989) expressed concern at the low conception rates to first insemination in high-producing dairy cows and suggested that a contributory factor may be an excess of rumen-degradable protein leading to toxic effects of ammonia and its metabolites on gametes and/or the embryo. More recently Elrod and Butler (1993) have provided data suggesting that degradable protein intakes which were 50% above the requirements for maximum microbial protein synthesis reduced embryo survival in dairy heifers. The objective of the present study was to investigate the effect in ewes of varying the amount of rumen degradable protein during the pre-ovulatory progesterone priming phase and the first four days thereafter on ovulation, fertilization, early in vivo and subsequent in vitro ovum development.