Ruminal Nitrogen Degradability Research Articles

Effects of soil type on density of trees and nutritive value of tree leaves in selected communal areas of South Africa

This study aimed to describe the distribution and nutritive value of woody species growing in clay-loamy and red-brown sand from selected localities of North West, South Africa. Three 2.2 km transects, radiating from homesteads, which served as replicates, were established at each of four selected grazing areas. Nine 10 × 10 m homogenous vegetation units (HVU), 20 m apart, were marked in each transect. Woody plant density, height and canopy cover (CC), were recorded, and chemical properties and degradability via in vitro ruminal fermentation of harvested leaves were measured. Raisin bush (Grewia flava), Buffalo thorn (Ziziphus mucronata) and Camel thorn (Vachellia erioloba) were the common species across both soil types. Soil type influenced (P <0.05) plant density, CC, total tree equivalent (TTE) and plant height. Areas with red-brown sandy soil had higher (P <0.05) total plant density (827.7 plant/ha), CC (9.6%) and TTE (2886.4 TTE/ha) than those with clay-loamy soil. Vachellia erioloba leaves in clay-loamy soil had the highest (P <0.05) crude protein content (151.2 g/kg DM). Leaves of Searsia lancea species that were harvested from both the clay-loamy and red-brown sandy soils had the highest (P <0.05) amounts of condensed tannins (0.915 AU550/200 mg and 0.917 AU550/200 mg, respectively). Searsia lancea leaves had the lowest (P <0.05) in vitro ruminal nitrogen degradability values in both soil types. The leaves of Z. mucronata and G. flava leaves have potential as protein supplements for ruminants owing to their higher crude protein content and in vitro ruminal N degradability.
 Keywords: canopy cover, feeding value, plant height, semi-arid, species diversity, tree equivalent

Silage additives to reduce protein degradation during ensiling and evaluation of in vitro ruminal nitrogen degradability

AbstractDespite the high degradability of their proteins, grass and legume silages represent an important option to reach more sustainable livestock systems. To improve the nitrogen use efficiency of these crops, this study assessed the potential of several additives (chestnut tannins, oak tannins, zeolite, erythritol by‐product solution and wood molasses) to reduce proteolysis in the silo and in vitro nitrogen degradability. Ryegrass (Lolium multiflorum) and red clover (Trifolium pratense) were ensiled in varying proportions in laboratory‐scale silos made of vacuum‐packed plastic bags. Dry‐matter content, chemical composition, pH, ammonia and volatile fatty acids content were analysed after 34 days of ensiling. Ruminal nitrogen degradability was assessed in vitro (Aufrère & Cartailler, ). We observed that the proportion of ammonia in silage was reduced by the addition of oak tannin (−12%) and zeolite (−16%). The addition of zeolite lowered in vitro organic matter digestibility. Rapidly degradable nitrogen (1‐hr degradability) was reduced in vitro by both tannins (−6.8% for chestnut and −6.6% for oak) and zeolite (−5.8%), but total degradable nitrogen (24‐hr degradability) was only reduced by oak (−6.5%) and chestnut tannins (−7.3%). It suggests that tannins protected proteins from plant and bacterial enzymes by forming a complex that better resists silage fermentations and in vitro protease action. The reduction effects on proteolysis in the silo and on in vitro ruminal nitrogen degradability are limited individually but could be cumulative. Erythritol by‐product solution and wood molasses had no effect on silo or in vitro proteolysis.

Optical chlorophyll measurements as predictors of total nitrogen, nitrogen fractions and in vitro ruminal nitrogen degradability in tropical grass forages

This study evaluated whether the FieldScout CM 1000 NDVI and Yara N–Tester models can produce accurate and reliable estimates of nitrogen (N), buffer-soluble nitrogen (BSN), buffer-insoluble nitrogen (BISN), non-protein nitrogen (NPN) and in vitro ruminal nitrogen degradability after 3, 12 and 24 h incubation (ND3, ND12 and ND24) in three tropical grasses: Brachiaria hybrid, Megathyrsus maximus and Paspalum atratum. Correlation between the Yara N-Tester and N, BISN and in vitro ruminal N degradability of the Brachiaria hybrid and M. maximus were high (r 0.67–0.83). The Yara N-Tester accounted for 81% and 86% (p 0.000) of N variability in the Brachiaria hybrid and M. maximus, respectively. The Yara N-Tester prediction models explained 72% and 70% (p 0.000) BISN variability in the Brachiaria hybrid and M. maximus, respectively. In vitro ND24 of the Brachiaria hybrid (R 2 0.75) and M. maximus (R 2 0.75) was also best predicted with the Yara N-Tester. Model validation showed generally low (≤0.90) concordance correlation coefficients except for Yara N-Tester N and ND24 in M. maximus. Random error was the main source of error. We conclude that the accuracy of the Yara N-Tester prediction models was superior to that of the FieldScout CM 1000 NDVI models, and that the Yara N-Tester can produce accurate and reliable estimates of Brachiaria hybrid and M. maximus N and M. maximus ND24.

Change in Nitrogen Fractions and Ruminal Nitrogen Degradability of Orchardgrass Ensiled at Various Moisture Contents and the Subsequent Effects on Nitrogen Utilization by Sheep

The effect of various moisture contents of fresh forage on the change in nitrogen (N) fractions, in vitro ruminal N degradability, and the subsequent N utilization of silage in sheep were evaluated. Orchardgrass (Dactylis glomerata L.) with high (HM, 76%), medium (MM, 65%) and low (LM, 40%) moisture contents were ensiled into silos of 120 L capacity for 120 days. A nitrogen balance trial was conducted using a 4×4 Latin square design consisting of four dietary treatments (i.e. fresh forage, HM, MM and LM silages) and four wethers. With respect to N fractions, fraction 1 (buffer solution soluble N), fraction 2 (buffer solution insoluble N- neutral detergent insoluble N), fraction 3 (neutral detergent insoluble N-acid detergent insoluble N), and fraction 4 (acid detergent insoluble N) were determined. The proportion of fraction 1 in silages tended to decrease, while the in vitro ruminal degradability of insoluble N increased (p<0.05) with lower moisture contents at ensiling. Consequently, nitrogen utilization in sheep tended to improve as the moisture content of ensiled grass was decreased, with a negative correlation (p<0.01) between urinary N and the in vitro ruminal degradability of insoluble N. The averaged N retentions for HM, MM, and LM silage treatments were 59, 73 and 79% of that for fresh forage, respectively. (Asian-Aust. J. Anim. Sci. 2005. Vol 18, No. 9 : 1267-1272)

Grain Processing, Forage-to-Concentrate Ratio, and Forage Length Effects on Ruminal Nitrogen Degradation and Flows of Amino Acids to the Duodenum

The objectives of this study were to evaluate effects of dietary factors that alter ruminal fermentability on rumen N degradation, microbial protein synthesis, duodenal flows, and digestibility of amino acids (AA) in the intestines and the total tract. The experiment was a double 4×4 quasi-Latin square with a 23 factorial arrangement of treatments. The dietary factors were extent of barley grain processing, coarse (processing index; PI = 75.5%) or flat (PI = 60.2%); forage-to-concentrate (F:C) ratio, low (35:65) or high (55:45) on a DM basis; and forage particle length (FPL), long (7.59mm) or short (6.08mm). Eight lactating cows with ruminal and duodenal cannulas were offered ad libitum access to a total mixed diet. There were no significant interactions between dietary treatments for ruminal N degradation or its duodenal flow and digestibility in the intestines. Passage of microbial protein to the duodenum was improved with increased F:C ratio of the diet but was not affected by grain processing or FPL. Ruminal digestibility of N was increased with increased F:C ratio (49 vs. 60%) and with reduced FPL (59 vs. 50%). Increased grain processing improved N digestibility both in the intestine (15%) and in the total tract (8%). Reduction in the FPL of the diets reduced intestinal N digestion by 14% without affecting the N digestion in the total tract. Increased extent of grain processing tended to enhance duodenal flows of AA. In contrast, reducing FPL lowered flows of dietary AA to the duodenum because of lowered flows of feed plus endogenous N. Increased F:C ratio of the diet did not change the flow of total AA, but there was a reduced flow of dietary AA and increased flow of microbial AA. Flows of several individual AA were increased by feeding flatly rolled barley with limited effects of F:C ratio or FPL. An interaction between grain processing and FPL was detected for flows of some AA. Diets formulated with flatly rolled barley plus long FPL increased Arg, Thr, Asp, Glu, Ser, Tyr, and nonessential AA (NEAA) by more than 24%, compared with other combinations of grain processing and FPL. Digestibility of essential AA (EAA) in the intestine (68%) was higher than that of NEAA (63%), but digestion of total AA (65%) was similar to that of total N (66%). Digestibilities of individual AA in the intestine ranged from 46 to 77% and were generally improved with increased grain processing. However, effects of F:C ratio or FPL on digestion of AA were limited. These results indicate that manipulation of dairy cow diets can improve ruminal N degradation, microbial protein synthesis, flows of AA to the duodenum, and intestinal digestibility of AA. Combining dietary factors can be more beneficial than changing individual dietary factors for improving the delivery of AA to the small intestine.

Change in Nitrogen Fractions and Ruminal Nitrogen Degradability of Orchardgrass and Alfalfa during the Ensiling Process and the Subsequent Effects on Nitrogen Utilization by Sheep

In order to determine the extent of change in nitrogen fractions and in vitro ruminal degradability of forage protein during ensilage and the influence on nitrogen utilization by sheep, orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago saliva L.) were ensiled in separate 120 L silos for 5, 21 and 56 days. With respect to nitrogen fractions, fraction 1 (buffer solution soluble nitrogen), fraction 2 (buffer solution insoluble nitrogen-neutral detergent insoluble nitrogen), fraction 3 (neutral detergent insoluble nitrogen-acid detergent insoluble nitrogen), and fraction 4 (acid detergent insoluble nitrogen) were determined. Fractions I and 2 accounted for more than 80% of total nitrogen in orchardgrass and 90% of that in alfalfa. The proportion of fraction 1 in orchardgrass increased from 33.0% at day 0 to 52.0% after day 56 of ensiling. In the case of alfalfa silage it was 41.7% and 62.9%, respectively. Seventy percent of this increase occurred within the first 5 days of ensiling. A similar change of in vitro ruminal degradability of total nitrogen was also observed in both forages. Nitrogen retention in sheep tended to decrease as the length of ensiling increased, with a significantly positive correlation between urinary nitrogen and fraction 1, and in vitro ruminal degradability of total nitrogen.

Effects of Spontaneous Heating on Estimates of Ruminal Nitrogen Degradation in Bermudagrass Hays from Two Harvests

Estimates of rumen degradable or escape N are an important component of current nutritional models for feeding livestock, but attempts to estimate these fractions for bermudagrass [Cynodon dactylon (L.) Pers.] have been limited, and the relationship between concentrations of these fractions and spontaneous heating during bale storage has not been evaluated. The objectives of this study were to (i) assess the relationship between rumen escape or degradable N and spontaneous heating in bermudagrass hays harvested from the same site during 1998 and 1999 and (ii) correlate estimates of rumen escape and degradable N with other measures of forage nutritive value that are evaluated commonly. A preparation of Streptomyces griseus protease was utilized in an in vitro laboratory procedure to quantify rumen degradable N in hays that heated spontaneously during storage in small haystacks. Maximum temperatures in these bales ranged from 37.1 to 69.8°C over 2 yr. Rumen escape N for 40 hays ranged from 407 to 613 g kg−1 N and increased linearly (P &lt; 0.05) with all indices of spontaneous heating in both 1998 and 1999; however, r2 statistics were highest for bales made in 1998 (r2 ≥ 0.588). Similar results were observed when ruminal escape N was expressed as a proportion of plant DM. Rumen degradable N expressed as a proportion of plant DM was related to indices of heating (P &lt; 0.0001) when harvest years were evaluated together, but the slopes were not significant (P &gt; 0.05) for specific harvest years.

Estimation of intestinal digestibility of undegraded sunflower meal protein from nylon bag measurements. A mathematical model.

Ruminal nitrogen degradation and intestinal digestibility (ID) of the undegraded nitrogen of three sunflower meals were determined on three wethers fitted with rumen cannulae and T-type duodenal cannulae using nylon bags. Meals were obtained from semi-dehulled seeds by conventional hexane extraction (samples SD1 and SD2) or from whole seeds by a discontinuous procedure of pressing and hexane extraction (sample W), which causes a superior thermal effect. Therefore, effective degradability of nitrogen for the W sample (0.537) was lower (P < 0.001) than for conventional meals. Between the latter, SD2 had a lower value (P = 0.019) than SD1 (0.776 and 0.812, respectively). ID decreased in all meals (P < 0.001) as the ruminal incubation time (t) increased. This evolution could be described accurately by an exponential curve as ID = s + he(-kit). A method is proposed for estimating the proportion of undegraded ruminal nitrogen digested in the intestines (Di) from 1) the above equation, 2) the undegradable (r) and the insoluble and potentially degradable (b) nitrogen contents of the feed and the degradation rate of the last fraction (k(d)), and 3) the rumen outflow rate of particles (k(p)). The Di value is shown to be: [equation: see text] The percentages of nitrogen from digested feed in the intestines obtained with this method were 15.1, 17.2 and 39.0 for SD1, SD2 and W, respectively. Resulting effective ID values of undegraded nitrogen were 0.804, 0.767 and 0.844. Undigested nitrogen after ruminal and intestinal incubations decreased in linear and quadratic form in all meals as ruminal incubation time increased.

Effect of whole cottonseed on energy partitioning and nitrogen balance in sheep

AbstractEnergy and nitrogen balance partitioning was studied in sheep given whole cottonseed (WCS), vetch hay and commercial concentrates. Sheep were offered diets containing 0 (CON) and 250 g/kg WCS at maintenance (LF) and twice maintenance (HF) levels. Digested energy, metabolizable energy (ME) and heat production (HP) were measured in a balance trial combined with indirect calorimetry. Dietary ingredients were also incubated in sacco in sheep rumens. Feeding WCS resulted in decreased energy digestibility at HF (0·718 v. 0·751) but not at LF. Loss of energy as methane expressed as a proportion of gross energy intake for CON and WCS respectively was 0·078 and 0·057 at LF and 0·061 and 0·051 at HF. In both diets, HP was similar at LF. In contrast HP amounted to 0·657 of the ME for CON and only 0·61 for WCS at HF.Apparent nitrogen digestibility was not affected by WCS consumption. Urinary nitrogen was similar for both diets at LF, but at HF it was higher in the WCS diet. Thus at HF, retained nitrogen was 045 and 0·12 of apparently digested nitrogen for CON and WCS respectively.Ruminal degradation of organic matter was proportionately 0·87 and 0·77 of apparent digested organic matter in the total tract for the CON diet, at LF and HF respectively and 0·80 and 0·73 for the WCS diet, at LF and HF respectively. In the four groups ruminal nitrogen degradation was equal to apparent whole-tract nitrogen digestion. It was concluded that feeding WCS may decrease metabolic HP in ruminants. Utilization of WCS could be improved by taking measures to decrease urinary nitrogen losses.

Effect of maturity stage of Italian rye grass and lucerne on ruminal nitrogen degradability

Effect of maturity stage of Italian rye grass and lucerne on ruminal nitrogen degradability

Ruminal Nitrogen Degradability and Escape of Wet and Dry Distillers Grains and Wet and Dry Corn Gluten Feeds

Solubility and rate and extent of ruminal digestion of nitrogen in wet distillers grains, dry distillers grains, wet corn gluten feed, and dry corn gluten feed were evaluated in the laboratory, in situ, and in vivo. Distillers grains protein was the most insoluble in modified Burrough's mineral mix, corn gluten feed protein the least insoluble, and soybean meal protein intermediate. In the in situ trial (trial 1), nitrogen of wet and dry distillers grains and nitrogen of wet and dry corn gluten feed disappeared at similar rates, respectively. However, nitrogen disappearance rates were greater for wet and dry distillers grains. In the rumen escape trial (trial 2), wet distillers grains, dry distillers grains, wet corn gluten feed, and dry corn gluten feed were fed as supplemental protein sources and a urea control served to estimate endogenous nitrogen flow. Non-ammonia-nonbacterial nitrogen reaching the duodenum was lowest for steers fed the urea treatment (20.9 g/day). Rates were higher for wet distillers grains (64.1 g/day) and dried distillers grains (74.7 g/day) treatments compared to wet corn gluten feed (41.3 g/day) and dry corn gluten feed (32.7 g/day) treatments. Percentage protein apparently escaping rumen fermentation was greater for steers fed wet distillers grains (47%) or dried distillers grains (54%) than for those fed wet corn gluten feed (26%) or dry corn gluten feed (14%).