Rumen NH3 Concentrations Research Articles

Effect of drinking water salinity on lactating cows’ water and feed intake, milk yield, and rumen physiology

Use of desalinated seawater in arid and semiarid regions for domestic, industrial, and agricultural purposes is on the rise. Consequently, in those regions, drinking water offered to lactating cows has lower salinity and mineral concentrations than in the past. Although water with total dissolved solids)TDS) of up to 1 000 ppm is considered safe for drinking, lower salinity level may affect rumen physiology, feed and water intake, or milk yield. Therefore, we evaluated the effect of drinking water salinity in an electrical conductivity (EC) range of 400 to 1 000 micro Siemens (µS) / cm (TDS of 200 to 500 ppm) on lactating cows’ performance by artificially creating water EC > 400 µS/cm by adding NaCl. Following 2 weeks adaptation to individual feeders and troughs, four Israeli Holstein multiparous lactating cows were offered, in a Latin square design, drinking water with EC levels of 400, 600, 800 or 1 000 µS/cm, through addition of concentrated NaCl solutions (measured EC in troughs averaged 418, 624, 811, and 1 016 µS/cm and 209, 312, 406, and 508 TDS ppm, respectively), for four periods of 18 days each. Water EC in troughs was measured daily. Each period included 5 days for washout, 10 days for collecting data of feed and water intake, milk and milk component yields, and BW and 3 days for samplings of Milk, urine, feces, and rumen fluid. Rumen pH and temperature were recorded continually by inserting loggers into the reticulorumen. We analyzed the total tract apparent digestibility, rumen fluid volatile fatty acids and NH3, and mineral concentrations (Na, Cl, K, and N) in water, urine, feces, and milk. Drinking water salinity was positively correlated with DM intake and energy-corrected milk yield, the latter showing the greatest response between EC of 400 and 600 µS/cm. Digestibility of ash-free amylase-treated neutral detergent fiber was negatively correlated with water salinity. There was no significant effect of water EC on rumen volatile fatty acid or NH3 concentrations, or water intake. The results indicate possible effects of drinking water mineral concentrations on lactating cows’ milk yield and rumen physiology, warranting further investigation.

Digestion, nitrogen excretion and rumen microbial communities in beef cattle, and in vitro methane output, of fresh temperate grass with or without citrus pulp supplementation

The effects of supplementing grass with a high-energy, low-protein concentrate on intake, rumen fermentation, rumen microbial communities, apparent total tract digestibility and N-balance in beef cattle, and rumen fermentation and methane output in vitro, were studied. Sixteen Charolais steers (mean live weight (s.d.) 564 (24.3) kg)), were used in a completely randomised block design experiment, and offered either zero-grazed perennial ryegrass (Lolium perenne L.) ad libitum (GO), or the same grass with 2.25 kg citrus pulp dry matter (DM) daily (GCP). During the measurement phase, DM intake was restricted at 0.85 of their pre-determined intake. The same diets were incubated in an eight-vessel RUSITEC system. Supplementation decreased grass DM intake (6.59 vs. 7.54 kg/d) but increased total DM intake by 0.95 kg/d (P < 0.01). Rumen pH (P = 0.05) and NH3 concentration (P < 0.05) decreased, and total volatile fatty acid (VFA) concentrations (P < 0.01), molar proportions of propionate (P = 0.08) and butyrate (P < 0.05) increased for GCP compared to GO. Supplementation significantly altered the overall rumen microbial community structure compared to GO, driven principally by changes in relative abundance of Prevotella, Methoanobrevibacter and Lachnospiraceae genera. Plasma urea concentration was lower (P < 0.05) for GCP than GO. There was no effect (P > 0.10) of supplementation on apparent total tract digestibility of DM, OM and ADFom, but aNDFom digestibility tended to be lower (P = 0.07) and crude protein (N × 6.25) digestibility was lower (P < 0.01) for GCP compared to GO. Nitrogen intake (200 g/d) did not differ (P > 0.05) between treatments. Faeces N loss was 9 g/d greater (P < 0.01), and urine (P < 0.01) and total (P < 0.05) N losses were 22 and 13 g/d lower, respectively, for GCP compared to GO. In terms of N-balance (g/kg N intake), faecal N excretion was greater and urinary N excretion was lower (P < 0.01) resulting in a greater N use efficiency (P = 0.06) for GCP than GO. In vitro rumen NH3 concentrations were lower (P < 0.01) for GCP compared to GO, whereas in vitro rumen pH, lactic acid, VFA concentrations and molar proportions, and methane and total gas output did not differ (P > 0.05) between treatments. Supplementing grass with a low-protein, high-energy feed may be a strategy to reduce urinary and total N excretion in beef cattle grazing temperate grass pasture.

Feeding pellets inoculated with Bacillus amyloliquefaciens strain H57 improves production parameters in young Merino wethers

The objective of the study was to determine if feeding the probiotic Bacillus amyloliquefaciens strain H57 (‘H57′) to young Merino wethers can improve their feed intake, productivity, energy metabolism and rumen fermentation parameters. Thirty-six Merino wethers were housed in individual pens and fed ad libitum a high-fibre pelleted diet (Control group, n = 18), or the same pelleted diet inoculated with H57 (H57 group, n = 18) for a four-week Treatment period. This was followed by a two-week Carry-over period when all wethers were fed the pelleted diet without H57. Intake of pellets was measured daily (dry matter intake, DMI), live weight (LW) and body condition score (BCS) were measured weekly, and the LW gain (LWG) and feed conversion ratio (FCR) were calculated from the DMI and LWG. During the six-week experimental period, samples of blood and rumen fluid were collected four times and analysed for blood enzymes, metabolites, hormones and rumen fermentation parameters. In the Treatment period, the H57 group had 25% larger final LW than the Control group (6.0 vs 4.8 kg, P = 0.045) and had a greater BCS (2.94 vs 2.44, P = 0.014) and DMI of pellets (1429 vs 1337 g/day, P = 0.033), resulting in a better FCR (6.8:1.0 vs 8.4:1.0, P = 0.049). The increases in final LW and BCS were most marked in the initial two weeks of the Treatment period, but persisted over the remaining two weeks and continued, albeit to a smaller extent, during the Carry-over period. Blood metabolites, enzymes and hormones did not differ between the two groups and were within the expected reference ranges for sheep. Rumen NH3 concentrations were elevated (P = 0.033) in the H57 group throughout the experiment, but overall the volatile fatty acid (VFA) concentrations were not different. B. amyloliquefaciens was present in H57 pellets throughout the Treatment period, and consequently was detected in the rumen fluid and faeces of the H57 group. In conclusion, young Merino wethers fed high-fibre pellets inoculated with H57 for four weeks grew faster, converted the pellets into final LW more efficiently and had a higher BCS than peers fed the same pellets without H57. This can be important when feeding high-fibre pellets to transition young Merino wethers onto a finishing diet. The mechanisms behind these responses remain to be elucidated.

Roles of tree and shrub legume leaves as protein sources for cattle raised by small farmers in Bangkalan Regency

Inclusion of tree or shrub legume leaves in the ration of beef cattle improved quality and the main indicators are the increase in crude protein content and digestibility. The present study was done from March to September 2023 involving 30 farmers in Bangkalan regency who raised madura cattle and the information gathered were type and number of feeds offered daily. Tree and shrub legume leaves such as Gliricidia, Moringa, Indigofera, and jackfruit are the most common protein sources used to supplement field grass or straws. Samples of forage were taken and the following rations were formulated to simulate cattle feed: A (grass only); B (60% grass + 40% gliricidia); C (60% grass + 40% moringa); D (60% grass + 40% Indigofera); E (60% grass + 40% jackfruit) leaves. Parameters measured using an in vitro gas production technique showed that supplementation with tree and shrub legume leaves on field grass basal diet improved dry matter digestibility (DMD) and organic matter (OMD) values and this was closely related to improvements of rumen NH3 concentration which also contributed to efficiency of microbial protein synthesis (ESPM) value improvement. It can be concluded that tree and shrub legume leaves have shown important roles in improving the quality of field grass based diet for Madura cattle.

PENGARUH SUPLEMENTASI SILASE CAMPURAN SORGHUM- Clitoria ternatea PADA BERBAGAI LEVEL KONSENTRAT MENGANDUNG ZnSO4 DAN Zn-Cu ISOLEUSINAT TERHADAP FERMENTASI RUMEN KAMBING KACANG (Effects of supplemented mixed silage of sorghum-clitoria ternatea with.....)

The purpose of this study was to determine the effect ofsupplemented mixed silage of sorghum-Clitoriaternatea with different levels of concentrate containing ZnSO4 and Zn-Cu Isoleusinate on rumen fermentation of kacang goats. Twelve buck kacang goats aged 12-14 months with initial body weight ranged 11-19 kg andthe average was 14,40 kg while 14,93% coefficient of variation was used in this reseach. Methode used was experiment methode with block randomized design as research design consist of four treatments and three replication. The treatmenten were T1 = mixed silage of sorghum-Clitoriaternatea providing, T1, T2 and T3 was T1 supplemen by concentrate with level of 10, 20 and 30 % containing of 150 mg ZnSO4 and 2% Zn-Cu Isoleusinat respectively. Parameter measured was rumen pH value, NH3 and total of VFA concentration. The data obtained was analyzed by analysis of variance (ANOVA) and followed by Least Significant Different test. The results of statistical analysis showed that supplementation with various levels of concentrates containing 150 mg ZnSO4 and 2% Zn-Cu Isoleucine had no significant effect (P&gt; 0.05) on rumen pH and NH3 concentration, while significantly efect (P &lt;0.05) on VFA totalt. It can be concluded that supplementation with various concentrates containing ZnSO4 and Zn-Cu Isoleucicate produced relatively the same pH and NH3 and VFA tended to increase, with the best concentration of concentrate supplementation at 30%.

KARAKTERISTIK FERMENTABILITAS DALAM RUMEN PADA PELEPAH SAWIT FERMENTASI YANG DISUPLEMENTASI TEPUNG KULIT JENGKOL

Palm fronds are one of by-product plantation that ware potential used as animal feed. But the weaknesses were low digestibility and low nutrition. The processing of palm fronds with fermentation technology which combined with the addition of jengkol peel was one of method to improving the nutrition quality. The purpose of this study was to measure the digestibility and characteristics of rumen fluid in fermented palm oil fronds supplemented with jengkol peel powder. This study was designed in completely randomized with four treatments supplementation of jengkol peel powder at 0, 2, 4, and 6% and four groups as replications. Parameters analyzed were pH value, NH3 concentration, total VFA production, dry matter and organic matter digestibility. The data were analyzed using ANOVA and different among treatments means examined by Duncan Multiple Range Test. The result showed that the addition of jengkol peel powder at 2-6% to fermented palm fronds decreased (P<0.05) in-vitro dry matter and organic matter digestibility, rumen pH value, VFA Production and NH3 concentration. From this study it can be concluded that supplementation of jengkol peel powder on fermented oil palm fronds can reduce the digestibility of dry matter and organic matter in vitro, affecting the characteristics of rumen fluid (pH, VFA and NH3), but is still at optimal conditions for normal fermentation in rumen.

413 Effect of chitosan inclusion and dietary crude protein level on rumen fermentation in beef heifers fed a total mixed ration

Abstract Chitosan (N-acetyl-D-glucosamine polymer) is a natural biopolymer, which is the second most abundant organic compound on earth, found in lower plants and some arthropods and crustaceans. Studies with ruminants have shown that supplementing with chitosan can alter ruminal fermentation, including higher propionate concentration and lower acetate to propionate ratio, improving the energy efficiency within the rumen though data on nitrogen metabolism is lacking. Therefore, the objective of this study was to evaluate the effects of chitosan with different dietary crude protein (CP) inclusion on rumen fermentation in beef heifers. Eight ruminally cannulated Belgian Blue x Holstein Friesian heifers (752 ± 52Kg BW) were allocated one of four dietary treatments in a 2 x 2 factorial Latin Square design (n = 8). Diets were offered as total mixed ration (TMR) consisting of grass silage plus concentrate. Diets were offered once daily ad libitum. Dietary treatments were as follows: high CP (16%) +/- chitosan (10g kg-1 DMI) supplementation (HP+) or (HP-) and low CP (12%) +/- chitosan supplementation (LP+) or (LP-). Experimental periods were 25d in duration (14 d dietary adaptation and 10 d sampling). Rumen fluid was collected via cannula every 2 h post feeding for analysis of ruminal pH, ammonia (NH3) and volatile fatty acids (VFA) over a 48-hour period. Data was analysed using Proc Mixed procedure in SAS. Significant differences were considered when P &amp;lt; 0.05. Dietary treatment had no effect on ruminal pH (P &amp;gt; 0.05). Chitosan supplementation had no effect on ruminal NH3 and VFA concentrations (P &amp;gt; 0.05), whereas, animals offered 16% CP had higher concentrations of ruminal NH3 (P &amp;lt; 0.001). In conclusion, supplementing a TMR diet fed to beef heifers with chitosan had no effect on rumen fermentation. However, reducing dietary CP concentration fed to beef animals resulted in lower rumen NH3 concentrations.

Diurnal Concentration of Urinary Nitrogen and Rumen Ammonia Are Modified by Timing and Mass of Herbage Allocation.

Simple SummaryLow nitrogen use efficiency in grazing dairy cows leads to high urinary N excretion, which contributes to greenhouse gases emission. This problem has been associated with high N and low energy intake, increasing rumen ammonia (NH3) concentration, and thereby, increasing urinary N excretion. Under this situation, it is important to discover nutritional and grazing management strategies that allow reduced urine N excretion in the pasture. This study evaluated whether changes in time of herbage allocation and herbage mass modify the diurnal pattern of urinary nitrogen (N) concentration and ruminal NH3 of lactating dairy cows. We found that the combination of time of herbage allocation and herbage mass modified rumen NH3 production and urinary N concentration. Results suggest that maintaining cows in the holding pen at the milking parlor for two hours after morning and afternoon milking could allow collection of urine from cows in the slurry pit during peak N concentration, returning cows to the pasture at a time of day when urinary N concentration is decreased.The objective of this work was to evaluate whether changes in time of herbage allocation and herbage mass (HM) (low (L) or medium (M)) modify the diurnal pattern of urinary nitrogen (N) concentration and ruminal ammonia (NH3) of lactating dairy cows. Four Holstein-Friesian cows fitted with rumen cannula were randomly allocated to one of four treatments: 1) low herbage mass in the morning (L-AM) (Access to new herbage allocation after morning milking with a herbage mass (HM) of 2000 kg DM/ha); 2) low herbage mass in the afternoon (L-PM) (Access to new herbage allocation after afternoon milking with a HM of 2000 kg DM/ha); 3) medium herbage mass in the morning (M-AM) (Access to new herbage allocation after morning milking with a HM of 3000 kg DM/ha); and 4) medium herbage mass in the afternoon (M-PM) (Access to new herbage allocation after afternoon milking with a HM of 3000 kg DM/ha). A four by four Latin Square design with four treatments, four cows, and four experimental periods was used to evaluate treatment effects. Rumen NH3 concentration was greater for L-AM compared to L-PM and M-PM at 13:00 and 16:00 h. Urine urea and N concentrations were lower for M-AM compared to L-AM. Urine N concentration was greater for L-AM than other treatments at 10:00 hours and greater for M-PM compared to M-AM at 16:00 hours. Results suggest that maintaining the cows in the holding pen at the milking parlor for two hours after morning grass silage supplementation for L-AM and for two hours after afternoon grass silage supplementation for M-PM, could allow collection of urine from cows at the holding pen and storage of urine in the slurry pit during the time of peak N concentration, returning cows to the pasture at a time of day when urinary N concentration is decreased.

THE EFFECT OF GIVING CONCENTRATES CONTAINING KELOR LEAF FLOURS WITH DIFFERENT LEVELS ON NITROGEN UTILISATION OF LOCAL GOAT

The study aimed to determine the effect of the use of feed concentrates containing Moringa leaf flour on protein consumption, protein digestibility and rumen ammonia concentration. Data were analyzed using a randomized block design (RBD) with 4 treatments and 3 replications, and continued with the Duncan test. The treatments in this study include: K1: Concentrate without the use of Moringa leaf flour; Concentrate with the addition of 10% Moringa leaf flour; K3: Concentrate with the use of Moringa leaf flour 20%; and K4: Concentrate with the use of 30% Moringa leaf flour. The variables determined were Rough Protein Consumption and Digestion and rumen NH3 Concentration. The results showed that protein (g / tail / day) consumption and crude protein digestibility (%) were highest in the treatment of K4: 36.37 and 72.01, then followed by K3: 35.81 da. 71.93; K2: 35.06 and 69.85 and K1: 31.99 and 59.91. The highest rumen NH3 (mM) concentration is also occupied by K4: 19.77 followed; K3: 18.24; K2: 16.48 and K1: 11.16. The results of statistical analysis showed that the treatment had no significant effect (p&gt; 0.05) on consumption and had a significant effect (p&lt;0.05) on the digestibility coefficient of crude protein and rumen NH3. It was concluded that the use of Moringa leaf flour as a constituent component to the level of 30% can be used for animal feed to increase consumption and nutrient digestibility of livestock as well as the provision of rumen NH3.

Investigating the effects of sex of growing Nellore cattle and crude protein intake on the utilization of recycled N for microbial protein synthesis in the rumen by using intravenous 15N15N-urea infusion

The aim of this study was to investigate the effect of sex and levels of dietary crude protein (CP) on the recovery of 15N in microbial protein as well as to evaluate nitrogen balance compounds and variables related to urea renal handling in Nellore cattle. Four Nellore bulls and four Nellore heifers, fitted with rumen cannulas, were distributed in a two 4×4 Latin square design. The four experimental diets differed in levels of CP: 90.0, 110.0, 130.0, and 150.0g/kg on a dry matter basis. Continuous intravenous infusion of 15N15N-urea solution was provided at a rate of 0.30mmol urea/h followed by determination of 15N in ruminal bacteria, ammonia (NH3), and feces to determine the incorporation of recycled N in rumen bacteria. The increased dietary CP revealed a linear increase (P<0.05) in total digestible nutrients (TDN), total digestibility of CP and neutral detergent fiber (NDF), retained nitrogen, urinary excretion of urea-N, amount of filtered and absorbed urea (g/day), and plasmatic concentrations of urea-N. Fecal excretion of N presented a linear increase (P<0.05) in relation to dietary CP. Rumen NH3 concentration increased in a linear fashion (P<0.05), and rumen 15N-NH3 contents and fecal 15N contents decreased in a linear fashion (P<0.05) with increasing dietary CP. The regressions NH3=23.6183×e(0.0104×NI) and 15N-NH3=−0.00062×NI+0.1219 were obtained in order to calculate rumen NH3 concentrations (mg/l) and 15N-NH3 (atom percent excess), respectively, as a function of N intake (NI, g/day). The contents of total-N and 15N did not differ between liquid-associated bacteria (LAB) and particle-associated bacteria (PAB). There was no effect of sex (P>0.05) on the percentage of infused 15N that was recovered from feces and bacteria. There was no effect of dietary CP level on the percentage of 15N infused in plasma that was recovered from feces. However, there was a decreasing linear effect of the level of dietary CP (P<0.05) on the percentage of 15N infused in the jugular vein recovered from bacteria. We concluded that microbial protein synthesis was not affected by sex. The LAB and PAB had the same total-N content and recovery of infused 15N-urea. The greater recovery of infused intravenous 15N-urea on microbial protein synthesis in a low CP diet suggests greater urea recycling in association with this diet.

Effect of replacing organic grass-clover silage from primary growth with regrowth on N digestion in dairy cows

Clover proportions, and thereby chemical composition of herbage, differ between primary growth (PG) and regrowth (RG) in organic managed grass-clover fields. The characteristics of PG and RG silages suggest different supplementary feeding strategies to sustain an efficient milk production in dairy cows. Silage made of the RG generally offers more crude protein (CP) in the diet than silage made of the PG because of an increasing proportion of clover later in the season. Additionally, grass and clover have different amino acid (AA) profiles. His has been suggested to be the first limiting AA in grass silage, while Met has been suggested to be the primarily limiting AA in red clover silage. Eight rumen cannulated Norwegian Red cows were used in two replicated 4×4 Latin squares with 21-days periods. Organic PG and RG silages were fed ad libitum in four diets with RG replacing PG silage in ratios of 0, 0.33, 0.67 and 1 on dry matter (DM) basis. Changing RG silage proportions from 0 to 1 increased daily CP intake from 2.90 to 3.08kg and rumen NH3-concentrations from 4.9 to 8.4mmol/L, but did not promote a better protein supply. Neither total ruminal outflow of AA nor the AA profile in the small intestine differed between dietary treatments. Met and His were probably the most limiting AA for a higher milk production. Limitations by His may be more related to diets based on PG, while production by cows fed diets based on more RG herbage were more likely limited by Met.

The effect on intake digestibility and microbial protein production of adding urea to rice straw for cattle and buffalo calves

Four cattle calves (Boss indicus) of average weight 120kg and four swamp buffaloes calves of average weight 220kg were fed four rice straw diets in a Latin square design. The rice straw were sprayed with 0%, 0.5%, 1% and 2% of urea and given ad libitum. Each period was 15 days during the last 5 days of which urine and faeces were collected. Urine samples were analysed for excretion of purine derivatives (PD) to measure microbial protein production.There was no significant effect on intake of rice straw which was 3.1, 3.4, 3.1 and 3.1 kgDM/day for cattle and 4.5, 4.5, 4.5 and 4.6kgDM/day for buffalo. Rumen NH3 concentrations were 39, 60, 70 and 96mg/l for cattle and 51, 81, 102 and 132mg/l for buffalo with significant difference. However the PD excretion in the urine was not significantly changed being 0.28, 0.19, 0.18 and 0.23mmol/kgW0.75 for cattle and as expected lower for buffaloes being 0.13, 0.11, 0.12 and 0.11mmol/kgW0.75. The dry matter digestibilities for cattle were 57.1, 60.3, 58.3 and 60.7 while for buffalo the digestibilities were 60.7, 57.4, 59.6 and 60.2.The results suggest that the rice straw containing 6% protein and digestibility between 57% and 60% provided sufficient crude protein for microbial needs.

Effects of supplementation of Bacillus subtilis natto Na and N1 strains on rumen development in dairy calves

Effects of Bacillus subtilis natto Na and N1 strains on ruminal development of papillae in dairy calves were investigated. Twenty four Holstein bull calves (7 ± 1.1 d) were randomly divided into three treatments of eight calves. The natto cultures Na and N1 were mixed with milk before weaning, or mixed with the concentrate portion of the diets after weaning. All calves were weaned when starter intake reach 20 g/kg of body weight. At weaning four calves were randomly selected from each group and slaughtered, and the remaining calves were fed the basal diet for additional 44 d and then slaughtered. Rumen fluid and ventral rumen tissue samples were collected from all calves. Results show that oral supplementation of B. subtilis natto Na or N1 reduced concentrations of short chain fatty acids in the rumen at weaning and 44 d after weaning (P<0.05). B. subtilis natto N1 reduced rumen pH and molar proportion of butyrate in both experimental periods (P<0.05), while B. subtilis natto Na decreased the molar proportion of acetate and ammonia levels at weaning (P<0.05) and depressed rumen NH3 concentration 44 d post weaning (P<0.05). The number and surface area of papillae per cm 2 rumen wall for Na and N1 groups tended to be higher than the control at weaning (P<0.10) and 44 d after weaning (P<0.01). Furthermore, rumen papillae were flattened and tongue-shaped without narrow stalks, clumping or parakeratosis in the calves treated with natto culture. This study demonstrates that oral administration of B. subtilis natto Na and N1 increased rate of rumen development in dairy calves.

The potential of sulla in pasture-based systems

A feed evaluation trial compared lamb growth, rumen function and protein synthesis from either pasture (perennial ryegrass (Lolium perenne)/white clover (Trifolium repens)-dominant), lucerne (Medicago sativa), sulla (Hedysarum coronarium, which contains condensed tannins (CT)) or a lucerne:sulla mixture. The 8 week trial involved 32 weaned ram lambs allocated to either pasture (80% ryegrass and 20% white clover), lucerne, sulla, or a 50:50 lucerne:sulla mixture (DM basis; 8 per diet). Measurements included feed intake, liveweight (LW) gain, rumen ammonia (NH3) and volatile fatty acid (VFA) concentrations. A sub-group of 16 lambs (4 from each treatment) were given a continuous infusion of 35S-cysteine and 35S-sulphate to measure the effect of diet on cysteine irreversible loss and absolute whole body protein synthesis (WBPS). Lambs fed pasture had the slowest (P<0.05) daily gains (116 g/day) and absolute WBPS (93 g/day) compared with lambs fed sulla (308 g LW and 152 g WBPS/day) or lucerne:sulla (281 g LW and 180 g WBPS/day). Lambs fed sulla had lower rumen NH3 concentrations (13.6 mmol/L), acetate:propionate ratios (2.6) and minor VFA concentrations (2.1%) suggesting less rumen proteolysis than lambs fed the other diets. Lamb performance was improved by feeding sulla or lucerne compared to pasture, and the lucerne:sulla mixture resulted in better performance than the average of the 2 species fed alone.

Methane-suppressing effect of myristic acid in sheep as affected by dietary calcium and forage proportion

The efficiency of myristic acid (14 : 0) as a feed additive to suppress CH4 emissions of ruminants was evaluated under different dietary conditions. Six sheep were subjected to a 6 x 6 Latin square arrangement. A supplement of non-esterified 14 : 0 (50 g/kg DM) was added to two basal diets differing in their forage:concentrate values (1 : 1.5 and 1 : 0.5), which were adjusted to dietary Ca contents of 4.2 and 9.0 g/kg DM, respectively. Comparisons were made with the unsupplemented basal diets (4.2 g Ca/kg DM). The 14 : 0 supplementation decreased (P<0.001) total tract CH4 release depending on basal diet type (interaction, P<0.001) and dietary Ca level (P<0.05, post hoc test). In the concentrate-based diet, 14 : 0 suppressed CH4 emission by 58 and 47 % with 4.2 and 9.0 g Ca/kg DM, respectively. The 14 : 0 effect was lower (22 %) in the forage-based diet and became insignificant with additional Ca. Myristic acid inhibited (P<0.05) rumen archaea without significantly altering proportions of individual methanogen orders. Ciliate protozoa concentration was decreased (P<0.05, post hoc test) by 14 : 0 only in combination with 9.0 g Ca/kg DM. Rumen fluid NH3 concentration and acetate:propionate were decreased (P<0.05) and water consumption was lower (P<0.01) with 14 : 0. The use of 14 : 0 had no clear effects on total tract organic matter and fibre digestion; this further illustrates that the suppressed methanogenesis resulted from direct effects against methanogens. The present study demonstrated that 14 : 0 is a potent CH4 inhibitor but, to be effective in CH4 mitigation feeding strategies, interactions with other diet ingredients have to be considered.

Provision of certain carbohydrate-based supplements to pasture-fed sheep, as well as time of harvesting of the pasture, influences pH, ammonia concentration and microbial protein synthesis in the rumen

A series of experiments was conducted to test the hypothesis that ‘synchronising’ the availability of carbohydrate and nitrogen (N) in the rumen of sheep, either by the feeding of carbohydrate-based supplements in relation to pasture intake or by provision of pasture with a higher ratio of these 2 nutrients, would benefit microbial protein synthesis (MPS). The response variables were rumen pH and ammonia (NH3), and urine allantoin was measured as an indicator of MPS. The animals used were adult castrate male sheep fitted with a rumen cannula. In experiment 1, rumen NH3 and pH were found to be at a maximum and minimum, respectively, 1–2 h after feeding kikuyu (Pennisetum clandestinum) grass and 3–4 h after feeding biennial ryegrass (Lolium multiflorum) with rumen N degradability (at 18 h in sacco) being 55 and 75%, respectively. In experiment 2, the infusion of sucrose at 4 h post-ingestion of ryegrass pasture (the anticipated time of peak rumen NH3 concentration) lowered peak NH3 concentration by 40 mg/dL (from 187 to 147 mg/dL) and raised urine allantoin excretion from 6.0 to 9.0 mmol/sheep.day compared with infusion of sucrose at –1, +1 or +7 h. When sucrose was infused, 1 h after being fed kikuyu (synchronous) at the expected time of peak rumen NH3 concentration, the NH3 peak (from 152 to 110 mg/dL) and rumen pH were reduced and urinary allantoin excretion raised (from 6.6 to 7.6 mmol/sheep.day) compared with sheep given sucrose 7 h after ingestion of kikuyu grass (asynchronous). In experiment 3, the feeding of fine-rolled barley grain at, or 2 h before, feeding kikuyu grass, to ‘synchronise’ the availability of rumen-fermentable carbohydrates (RFC) in the grain with the availability of N released from the grass, substantially reduced rumen NH3 and pH, and increased urine allantoin levels (from 10.1 to 11.8 mmol/sheep.day) compared with feeding barley at 4 or 6 h before feeding grass. In experiment 4, sheep were fed kikuyu or ryegrass cut in the early morning (AM) or late afternoon (PM), with the nutrient content varying only in water-soluble carbohydrates (64 v. 114 g/kg DM for ryegrass and 41 v. 80 g/kg DM for kikuyu, respectively) and percentage of dry matter. Sheep fed PM-ryegrass had a significantly lower rumen pH compared with sheep fed AM-ryegrass but there was no difference in rumen NH3 concentrations. Urinary allantoin secretion was substantially higher in the PM group than the AM group (8.7 v. 3.9 mmol/sheep.day). When sheep were fed PM-kikuyu the pH fell to lower values than for the AM-kikuyu (6.4 v. 6.8) and there was again no effect on rumen NH3 levels. Urine allantoin levels were higher (P = 0.006) (6.2 v. 5.6 mmol/ sheep.day) in PM-fed sheep. The results of these studies support the hypothesis that there are benefits in synchronising the availability of RFC with N in the rumen on MPS but this is not always associated with significant changes in rumen pH and NH3. The implications of these results are discussed in relation to the situation in which synchronisation of RFC and N may potentially benefit dairy cattle.

Effects of wet corn gluten feed and intake level on diet digestibility and rumen passage rate in steers (2001)

Including 40% wet corn gluten feed (WCGF) in the diet increased total tract digestion of organic matter and neutral detergent fiber (P<0.01), reduced total volatile fatty acid concentration (P<0.01), increased rumen NH3 concentration (P<0.01), increased rumen pH, and tended (P<0.06) to increase total tract digestion of starch. Furthermore, WCGF increased rumen passage rate of solid digesta (P<0.01) compared to diets containing no WCGF. Limit feeding reduced total tract digestion of organic matter and neutral detergent fiber (P<0.01), decreased total volatile fatty acid concentration (P<0.01), increased rumen NH3 concentration (P<.01), increased rumen pH at 0 and 12 hours after feeding, reduced rumen pH at 4 hours after feeding, and increased rumen liquid passage rate (P<0.02).

The influence of ammonia, biogenic amines and γ-aminobutyric acid on grass silage intake in sheep

We investigated whether biogenic amines alone, or a combination of NH3, amines and gamma-aminobutyric acid (GABA) influenced grass-silage intake, intake behaviour and rumen liquid content in sheep. Three diets were studied: a grass silage preserved with formic acid (4 litres/tonne) (FAS), FAS with 4.9 g amines/kg DM added (FAS+A), and FAS supplemented with a combination of N-components at the following concentrations: 2.7 g amines, 3.0 g NH3 and 5.0 g GABA/kg DM (FAS+C). The diets were offered ad libitum, once daily to six rumen-cannulated Texel wethers in a crossover design. Daily DM intake (DMI; g DM/d) tended to be influenced by diet (P = 0.08). The DMI of FAS+A was similar to that of FAS alone, whereas that of FAS+C tended to be higher. The mean rate of ingestion (g DM/min) over all feeding bouts tended to be the lowest for FAS+A (P = 0.06). No differences were found among the diets concerning intake behaviour during the principal meal. Average intake rate of the small meals tended to be the lowest for FAS+A (P = 0.06). Although rumen NH3 concentration was higher (P < 0.05) after the principal meal, rumen pH, osmolality, rumen pool size and liquid content were not significantly altered by adding amines or the mixture of N-components to FAS. We conclude that biogenic amines or N-containing products of protein fermentation in concentrations normally found in poor-quality silages do not reduce the intake of well-preserved formic acid-treated silage. A direct effect on chemostatic regulation of intake was not observed, but a slight negative effect on silage palatability cannot be excluded.

Rumen digestion and urinary excretion of purine derivatives in response to urea supplementation of sodium-treated straw fed to sheep

The present study examined the effect of urea-N supplementation of a N-deficient diet on digestion and metabolism in the rumen. Five Rasa Aragonesa ewes, each fitted with a rumen cannula, were offered alkali-treated barley straw ad lib. alone or supplemented continuously via the cannula with four levels of urea-N (3, 6, 9 and 12 g/d). Rumen NH3 concentrations increased in response to urea infusion (6-128 mg/l; P < 0.001). At the highest level of rumen NH3 concentration there was a significant increase, compared with the unsupplemented treatment, in dry matter (DM) intake (846-1206 g/d; P < 0.001) and apparent digestibility of DM (0.38-0.43), organic matter (0.38-0.45) and neutral-detergent fibre (0.41-0.49; P < 0.01). Rumen outflow rates of particulate matter and potential DM disappearances, assessed using nylon bags, were not affected by the experimental treatments, although fractional rate of DM disappearance increased significantly with increasing levels of urea infusion (2.4-4.6 per h). Urinary excretion of total purine derivatives increased with N supplementation, although the response was exclusively due to an increase in allantoin excretion (26.9-66.4 mg/kg live weight (W)0.75 per d; P < 0.001). Xanthine, hypoxanthine and uric acid excretion rates were constant, averaging 1.8 (SE 0.17); 5.4 (SE 0.21) and 7.2 (SE 0.36) mg/kg W0.75 per d respectively. The maintenance of a minimum rumen NH3 concentration (approximately 50 mg/l) was necessary to avoid significant reductions in DM intake and fermentation rate. Higher levels, however, may further increase microbial N flow at the duodenum, as suggested by the response in urinary allantoin excretion over the range of rumen NH3 concentrations.

The Influence of Different Protein Supply and Feeding Level on pH, Ammonia Concentration and Microbial Protein Synthesis in the Rumen of Cows

Abstract Rumen ammonia concentration and pH was measured every second hour throughout 24 hours in an experiment including 33 periods with 2–5 rumen and duodenal cannulated cows. The calculated microbial non ammonia nitrogen synthesis was related to the mean NH3 concentration the hours with an NH3 concentration below 2, 5, 10, 15 and 20 mg NH3-N per 100 ml rumen fluid and the calculated protein balance in the rumen (PBV). The results showed no influence on rumen NH3 concentration of feeding the same ration composition on two levels, although the pH was significantly depressed by the higher feeding level. There was good agreement between the calculated PBV and the measured mean NH3-concentration in the rumen. The microbial protein synthesis per kg totally digested carbohydrates was not influenced by the PBV or NH3 concentration within the observed range in the experiments. The results further showed, that there is a significant variation in the microbial protein synthesis which can neither be described to t...