Rumen Fluid Composition Research Articles

Metabolic-methane mitigation by combination of probiotic Escherichia coli strain Nissle 1917 and biochar in rumen fluid in vitro fermentation of dairy cow

In response to climate change, there have been various trials to reduce methane emissions from ruminant animals in the livestock industry, and one of the typical candidates is probiotics used as feed additives. We employed Escherichia coli Nissle 1917 (EcN) as a promising probiotic for the reduction of methane emissions and investigated the molecular mechanism of methane-reducing effects using CRISPR/Cas9. The anaerobic culture of EcN with biochar (BC) could significantly increase acetate and hydrogen production. Additionally, RNA-seq analysis revealed an upregulation in the expression of acetate synthesis genes, namely, pta, poxB, and ackA. Subsequently, treatment of rumen fluid with EcN significantly decreased methane and increased acetate and propionate production, as observed through the analysis of short-chain fatty acids, and these effects could accelerate with additional supplementation of BC. The observation of changes in the microbial composition of rumen fluid following treatment with EcN and BC was made through rumen metagenomic analysis and RT-qPCR. The results revealed an increase in acetogen and propionate producing bacteria abundance and a decrease in methanogen abundance. Based on these findings, the CRISPR/Cas9 system was employed to elucidate the molecular mechanism of the methane-reducing capability of EcN. Gene deletion was performed targeting the genes poxB, ackA, and pta as key factors in acetate pathway in E. coli. The knockout of poxB, ackA, and pta could lead to the elimination of the methane-reduction of EcN as well as acetate-producing abilities. Collectively, the methane reduction ability of EcN in rumen fluid is associated with its acetate production capability, and the addition of BC significantly enhances methane mitigation capability of EcN.

Effect of Total Mixed Ration on Growth Performance, Rumen Fermentation, Nutrient Digestion, and Rumen Microbiome in Angus Beef Cattle during the Growing and Fattening Phases

This study investigates the impact of varying concentrate levels in the diets of Angus beef cattle on their performance, nutrient digestion, and metabolism during the growth (7 to 12 months) and fattening (13 to 30 months) phases. Fifteen Angus steers were continuously fed and divided into low-concentrate (L) and high-concentrate (H) groups based on the fattening period and dietary formulations. Throughout each 9-week trial phase, a comprehensive range of parameters was systematically measured, including dry matter intake (DMI), average daily gain (ADG), gain-to-feed ratio (G/F), blood parameters, rumen fluid composition, and microbial diversity. In the fattening phases, an increase in concentrate levels resulted in a significant rise in the cattle’s DMI. Although there was a minor increase in ADG compared to the growing phases, this increase was not statistically significant. The efficiency of nitrogen (N) utilization in the cattle decreased, accompanied by a significant reduction in the apparent digestibility of nutrients. Ruminal fermentation produced more energy substances; however, there was a notable decrease in the abundance of fiber-decomposing microbes (such as the NK4A214_group, Ruminococcus, Papillibacter, and Acetitomaculum) and a significant increase in the abundance of starch-degrading microbes (including Bacteroidota and Prevotellaceae). Additionally, there was a significant reduction in the abundance of immune system-related functional pathways. This suggests that high-concentrate fattening does not necessarily lead to improved growth performance and may negatively affect metabolic health and nutrient digestion.

Effect of Preservation Temperature and Time on Fermentation Characteristics, Bacterial Diversity and Community Composition of Rumen Fluid Collected from High-Grain Feeding Sheep

This study aimed to explore the dynamic variations in fermentation characteristics, bacterial diversity and community composition at two preservation temperatures as preservation time extended. Six rumen fluid samples collected from high-grain feeding sheep were stored at −20 °C or −80 °C for 0 day, 7 days, 14 days, 30 days, 60 days, 120 days, and 240 days. The results showed that the current preservation temperature did not alter the fermentation characteristics, bacterial diversity and community composition (p > 0.05). The concentrations of ammonia, microbial crude protein, acetate, propionate, butyrate, valerate, and total volatile fatty acids were higher when stored at 60 days (p < 0.05). Preservation time had no influence on bacterial richness and evenness (p > 0.05), whilst the relative abundances of Bacteroidota and Prevotella were numerically higher when stored at 30 days, and the opposite results were observed regarding Firmicutes. Both principal co-ordinates analysis (PCoA) and non-metric multidimensional scaling (NMDS) showed clusters among treatments in terms of preservation time and preservation temperature. Analysis of similarities (ANOSIM) also revealed similarities between treatments (p > 0.05). This study indicates that most fermentation characteristics in rumen fluid were altered after a 60-day preservation, whilst the preservation time for rumen bacterial community profile alteration was 30 days. It is recommended to finish the sample determination of rumen fluid within 30 days. This study may assist decision-making regarding the practicable time for rumen fluid determination, as well as viable preservation conditions for inoculum used for in vitro fermentation testing.

Effects of supplementing a yeast culture in a pelleted total mixed ration on fiber degradation, fermentation parameters, and the bacterial community in the rumen of sheep

Feeding animals with pelleted total mixed ration (TMR) is a widespread practice as it reduces feed losses during storage, feeding and the animal’s sorting. Supplementation of yeast culture can promote rumen fiber degradation, which may occur through stabilizing rumen pH. There are few studies, however, evaluating the optimal supplementation level of yeast culture in pelleted TMR in which rumen pH has been continuously measured. This study aimed to determine the optimal level of a commercial yeast culture product (of which the number of viable CFU was not measured) mixed and pelleted with the TMR, on fiber degradation in situ, rumen pH dynamics, rumen fermentation variables, and the bacterial community composition of rumen fluid. Under a partial Latin square design, a total of twelve wethers equipped with permanent rumen fistulas were randomly assigned to four treatments of yeast culture at 0, 0.5, 1.0, or 2.0% dietary dry matter. After a 28 d period comprising 21 d for adaptation and 7 d for measurements, each group of three wethers was randomly reassigned to another treatment. Thus, each yeast supplementation level was fed to a total of six animals. In situ dry matter (DMD) and neutral detergent fiber (NDFD) disappearance of corn stover, mean rumen pH, total volatile fatty acids concentration, acetate, propionate, and n-butyrate molar percentages, and the acetate to propionate ratio were influenced (P ≤ 0.05) by dietary treatments. Quadratic (P ≤ 0.03) responses to increasing yeast culture supplementation level were observed for mean rumen pH, daily duration of pH below a 5.8 threshold considered inhibitory for fibrolysis, and the molar percentages of propionate, n-butyrate, and the acetate to propionate ratio. The highest in situ DMD and NDFD occurred when yeast was supplemented at 1%. Increasing yeast culture supplementation level tended to quadratically increase the abundance of fibrolytic bacterial genera NK4A214 and FD2005, which peaked at 1% yeast culture in the diet DM. The molar percentage of n-butyrate was positively correlated with the relative abundance of Rikenellaceae_RC9 and NK4A214. In our study, supplementation of pelleted TMR with 1% yeast culture provided as residual yeast medium components, was optimal for fiber degradation of forage fed to ruminants. Members of genera NK4A214 and FD2005 may contribute extra n-butyrate.

The effect of different doses of rye extrudate on the digestibility of the diet feeds and biochemical parameters of rumen fluid and blood in replacement heifers

The article presents the results of identifying the effect of feeding different doses of winter rye grain extrudate on the digestibility of diet feeds and the biochemical composition of rumen fluid and blood of replacement heifers. The research was carried out at the Sokolovo dairy complex (Perm Krai). The objects of the study were replacement heifers of Holstein blackand-white breed aged 12-15 months. The concentrate part in the diet of heifers of the experimental groups consisted from winter rye grain extrudate: in the first group by 12.5 %, in the second – by 25.0 %, in the third – by 50.0 %. As the result of the research, it was revealed that the replacement heifers of the first, second and third experimental groups showed great results compared to the heifers of the control group in the digestibility of the dry matter of the diet feed by 0.63 %, 0.99 and 1.77 % (p<0.01), respectively. The ammonia content was in the rumen fluid of the first experimental group of heifers three hours after feeding by 0.62 mg% (2.97 %) p<0.05, in the second experimental group by 1.22 mg% (4.77 %) p><0.05, in the third –> ˂ 0.05, in the second experimental group by 1.22 mg% (4.77 %) p˂0.05, in the third – by 1.70 mg% (9.42 %) p˂0.01 less, compared to the control. The level of urea in the blood of heifers of the experimental groups was lower, compared with the control, in the first ‒ by 0.34 mmol/l (by 6.65 %), in the second by 0.46 mmol/l (9.21 %) and in the third – by 0.58 mmol/l (14.90 %) p˂0.05.

Effect of a feed additive containing yeast cell walls, clove and coriander essential oils and Hibiscus sabdariffa administered to mid-lactating dairy cows on productive performance, rumen fluid composition and metabolic conditions

Thirty-six multiparous Holstein mid-lactating cows were housed in 6 pens (6 cows/pen) and allocated in two groups (3 pens/group), receiving a control total mixed ration (CTR), or the same diet supplemented with a feed additive (TRT). Between 15 and 35 days from enrolment (DFE) the dry matter intake (DMI) of each pen, and the individual milk yield (MY), rumination time (RT), the compositions of milk and rumen fluid and the metabolic profile of plasma were monitored regularly. At 35 DFE, cows started a 1-week wash-up period prior to the changeover. Data were analysed with a mixed model using repeated measures. Cows receiving the additive had higher DMI and MY (p < .01), a longer RT between 22 and 29 DFE (p < .05), a higher total VFA concentration and a lower pH in the rumen fluid (p < .01 and p = .04, respectively). At 15 DFE, TRT cows had a higher concentration of lactose in their milk, and lower concentrations of BHB, ceruloplasmin and haptoglobin, paired with higher concentrations of albumin, paraoxonase and aspartate aminotransferase in their plasma (p < .01). These outcomes suggest a positive effect of the additive on increasing DMI and MY, possibly reflecting that it had a combined action on the rumen and the liver. Highlights The additive increased feed intake, rumination time and milk yield. It improved rumen fermentations and liver activity, and mitigated ketogenesis and inflammatory conditions. Beneficial actions of the active components on rumen and liver functions could be hypothesised.

Evaluation of the therapeutic efficacy of rumen transfaunation.

Transfaunation is supposed to stimulate normal rumen function and has been used as an ancillary treatment for indigestion. Although it is widely recommended, there are little research data on the efficacy and the necessary volume.The objective of the prospective clinical trial was the evaluation of the therapeutic efficacy of two different transfaunation volumes which can be obtained under practical conditions.Forty‐five cattle suffering from indigestion were included in the study. A scoring system for the classification of rumen fluid was used. Scores were given in accordance with the importance of the parameter as an indication of microbial dysfunction. Animals with disturbed rumen fluid composition and activity were randomly assigned into 3 groups. Group 1 received 1 L of rumen fluid, group 2 received 5 L of rumen fluid and group 3 (control group) received 5 L of body temperature water. Rumen fluid analysis was repeated on days 1 and 4 after transfaunation. The feed intake of the animals was recorded.After the transfaunation of 1 L and 5 L, the rumen fluid score improved significantly from day 0 to days 1 and 4. Rumen fluid samples in the control group showed no significant improvement from day 0 to day 1.No significant differences were observed between the two treatment groups. But significant differences between the improvement of group 1 and the control group on days 1 and 4 and significant differences between group 2 and the control group on day 1 were detected. Small volumes of rumen fluid are easily obtainable by stomach tubes fitted with suction pumps. In summary, the transfaunation of as little as 1 L of rumen fluid caused significant improvement in the activity of rumen flora in cows suffering from indigestion.

Nutrient analysis of liquid organic fertilizer from agricultural waste and rumen liquid

Organic fertilizers are able to bind the ability of soil to absorb water, increase resistance to erosion, improve biodiversity, and increase soil fertility, but will not increase residuals on crop yields so it is safe for the environment and human health. Agricultural waste is a by-product of agriculture that is not utilized or thrown away so that it has no sale value like vegetable waste, rotten fruit, coconut fiber, agricultural waste, fisheries and household waste, which can directly cause environmental pollution, sources disease, and interfering with environmental cleanliness. Rumen cow is a slaughterhouse waste that is not utilized properly, even though the rumen still contains nutrients, microbes and undigested food that can be recycled. The objective of this study was to find out the ratio of the composition of rumen fluid and agricultural waste to the liquid organic fertilizer nutrient content. The analysis method used was 3x3 technique of rumen fluid for each control, namely PI 15% rumen fluid, PII 30% rumen fluid and PIII 45% rumen fluid. The results of the nutrient analysis of organic liquid fertilizer towards agricultural waste and rumen liquid showed that the highest nitrogen in PII is 1.85%, PIII was 1.29% and Pi was 0.68%. The highest phosphorus (P) content in PII was 2.52%, PIII was 2.47% and PI was 1.87% and the highest potassium (K) content was in PII (2.90), PIII was 2.72 and PI was 2.14. According to the results obtained, nutrient analysis of liquid organic fertilizer is in accordance with the quality standards of liquid organic fertilizer regulated in the Agriculture Regulation No. 28/Regulation of the Minister of Agriculture/OT.140/2/200 which stated that liquid organic fertilizer for its N-total content, Phosphorus and Potassium is greater of 2%.

Changes of ruminal pH, rumination activity and feeding behaviour during early lactation as affected by different energy and fibre concentrations of roughage in pluriparous dairy cows

ABSTRACTThe aim of this study was to assess differences of ruminal pH and rumination activity between the prepartal and postpartal period of cows and to investigate changes of feeding behaviour and ruminal fermentation depending on postpartal rations with slight differences in roughage energy and fibre concentration. Therefore, 11 rumen-cannulated German Holstein cows were used from 3 weeks antepartum until 16 weeks postpartum. During the dry period, all cows received the same diet. After calving cows were assigned to two groups receiving partial mixed rations with different energy concentrations (6.1 MJ NEL/kg DM [moderate], with 18% straw on dry matter [DM] basis, group MR) or 6.5 MJ NEL/kg DM [high], with 6% straw on DM basis, group HR). In both groups, concentrates were supplied on average at 45% of total DM intake. Circadian measurements of ruminal pH, ruminal temperature and rumination activity were conducted weekly during the transition period and bi-weekly after week 4 postpartum. Throughout the postpartal period, feed intake behaviour was measured, and twice during the experiment, rumen fluid composition and net-acid-base excretion in urine were determined. Mean ruminal pH, feeding behaviour, rumination activity and rumen fluid composition did not differ between the groups, whereas group HR exhibited higher diurnal variations of pH and had a lower rumen temperature than group MR postpartum. However, these differences also occurred during the prepartal period when groups received equal rations. It was observed that ruminal pH values and the risk for subacute ruminal acidosis (SARA) were increased during postpartal period, whereby the circadian pH values showed high cow-individual variations. Overall, differences of energy and fibre concentrations in roughage did not affect the observed variables, whereby it should be noted that the number of cows was quite low in this study. Our results suggest that the ruminal pH characteristics are rather cow individual, indicating that cows presumably differ in their susceptibility to develop SARA.

Oil palm frond supplementation can change fatty acid composition of rumen fluid, muscle tissue and blood cholesterol level in crossbred male sheep

Oil palm frond supplementation can change fatty acid composition of rumen fluid, muscle tissue and blood cholesterol level in crossbred male sheep

The Effect of Concentrate Supplementation on Voluntary Intake, Digestibility and Composition of Rumen Fluid of Goats Fed on Rye (Secale cereale L.) Silage

The Effect of Concentrate Supplementation on Voluntary Intake, Digestibility and Composition of Rumen Fluid of Goats Fed on Rye (Secale cereale L.) Silage

Effects of niacin supplementation (40 weeks) and two dietary levels of concentrate on performance, blood and fatty acid profiles of dairy cattle

The present study was conducted to investigate the effects of 24 g niacin (nicotinic acid (NA)) supplementation over 40 weeks with two forage-to-concentrate ratios (60% concentrate vs. 30% in the total diet) on performance variables of energy metabolism such as plasma concentrations of non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), glucose and nicotinamide (NAM), and the fatty acid profile in rumen fluid. In a 2 x 2 factorial design, 64 German Holstein cows were divided postpartum into four dietary groups: i) 60% concentrate supplemented with 24 g NA (Group 60 + NA); ii) 60% concentrate without NA (Group 60−); iii) 30% concentrate with 24 g NA (Group 30 + NA) and iv) 30% concentrate without NA (Group 30−). The experiment started on the day of calving and continued for 40 weeks. Niacin supplementation did not affect milk yield or composition. The plasma niacin content increased in the supplemented groups, especially Group 30 + NA. Niacin supplementation led to decreased plasma glucose concentrations. The interaction of concentrate x niacin enhanced the molar proportion of propionic acid in rumen fluid in Group 60 + NA. Total short-chain fatty acid (SCFA) concentrations were increased by level of concentrate, niacin supplementation and the interaction, concentrate x niacin. Plasma levels of NEFA and BHB remained unaffected. In sum, concentrate level, niacin supplementation and the interaction of concentrate x niacin increased plasma NAM concentration, whereas plasma glucose concentration was decreased by niacin supplementation. Keywords: Milk performance, nicotinic acid, plasma metabolites, rumen fluid composition

Effect of feeding according to energy balance on performance, nutrient excretion, and feeding behavior of early lactation dairy cows

The objectives of this study were to evaluate 2 feeding strategies for early lactation cows on performance and efficiency of nutrient utilization. Fifty-eight Holsteins cows were blocked by parity and production during the pretreatment period and then randomly assigned at 21 d postpartum to a control diet [n=29; 16.2% crude protein, 1.64Mcal of net energy for lactation (NEL), 22% starch, and 19% forage neutral detergent fiber (NDF)] or a diet with caloric density manipulated weekly (precision diet; n=29; 16.2% crude protein; 1.59 to 1.68 NEL; 18 to 26% starch; and 16 to 22% forage NDF) to promote a calculated positive energy balance of 5Mcal/day. Diets were fed as total mixed rations and precision cows had their diets adjusted individually once a week, by feeding additional grain supplementation from 0 to 25% of daily dry matter (DM) offered, according to the energy balance of the preceding week. Energy balance was calculated daily and then averaged weekly. The study lasted from wk 3 to 19 postpartum, and nutrient digestibility, rumen fluid composition, urinary output, estimates of microbial protein synthesis, and feeding behavior were evaluated between wk 9 and 13 postpartum. Compared with controls, precision cows had similar DM intake (24.3kg/d), but NEL intake tended to be greater primarily between wk 4 and 8 postpartum. Yields of milk (45.2 vs. 41.9kg/d), milk components, 3.5% fat-corrected milk (44.0 vs. 40.8kg/d), and energy-corrected milk (43.4 vs. 40.2) were all greater for precision than control cows, resulting in greater energy-corrected milk production per kilogram of diet DM consumed (1.79 vs. 1.72). Precision cows produced more milk calories per kilogram of metabolic weight (0.227 vs. 0.213Mcal of NEL/kg), although the amount of consumed calories partitioned into milk (82.3%) and measures of energy status did not differ between treatments throughout the study. Glucose concentrations were greater throughout the day in precision cows compared with controls at 6 wk, but not 13 wk postpartum. Apparent digestibility of nutrients, composition of rumen fluid, mean and low rumen pH, and estimated rumen microbial N synthesis remained mostly unaltered by treatments. Although precision cows produced more milk true protein, measures of efficiency of dietary N use were not influenced by treatment. On wk 13 postpartum, precision cows consumed a diet with longer NDF particles, which resulted in a tendency for greater intake of NDF >8mm because of less sorting against the long particles than control cows. Meal pattern differed with treatment, and precision cows consumed feed more sparsely throughout the day, spent more time ruminating lying, and had similar meal duration (mean of 36.3min/meal) compared with control cows, but smaller meal size (3.33 vs. 3.64kg/meal). Results from the current study indicate that allocating dietary resources according to the individual needs of cows based on energy balance improves lactation performance compared with feeding a single total mixed ration, despite similar average nutrient intake between treatments. Improvements in performance are likely related to allocation of calories based on the needs of the cow and on shifts of feeding behavior that might favor intake of smaller meals.

A metabolomics approach to uncover the effects of grain diets on rumen health in dairy cows

Dairy cows fed high-grain diets during early lactation have a high incidence of metabolic disorders. However, the precise mechanism(s) of how grain feeding causes disease is not clear. In an effort to understand how this diet transition alters the rumen environment and potentially leads to certain metabolic disorders in dairy cattle, we undertook a comprehensive, quantitative metabolomic analysis of rumen fluid samples from dairy cows fed 4 different diets. Using a combination of proton nuclear magnetic resonance spectroscopy, gas chromatography-mass spectrometry, and direct flow injection tandem mass spectroscopy, we identified and quantified 93 metabolites in rumen samples taken from 8 dairy cows fed graded amounts of barley grain (i.e., 0, 15, 30, and 45% of diet dry matter). We also studied temporal changes in the rumen by studying metabolite concentration differences between the first day and the last day of each diet phase following the diet adaptation period. Multivariate analysis showed that rumen metabolites arising from the diet containing 45% barley grain were clearly different from those containing 0, 15, and 30% barley grain. Likewise, a clear separation of the metabolic composition of the ruminal fluid was evident at the beginning and at the end of each diet phase—contrary to the belief that 11d are suitable for the adaptation of cows to high-grain diets. High-grain diets (>30%) resulted in increased rumen fluid concentrations of several toxic, inflammatory, and unnatural compounds including putrescine, methylamines, ethanolamine, and short-chain fatty acids. Perturbations in several amino acids (phenylalanine, ornithine, lysine, leucine, arginine, valine, and phenylacetylglycine) were also evident. The present study confirms and greatly extends earlier observations on dietary effects on rumen fluid composition and shows that the use of multiple metabolomic platforms permits a far more detailed understanding of metabolic causes and effects. These results may improve our understanding of diet-related rumen metabolism and the influence of grain on the overall health of dairy cattle.

Effect of tanniniferous Terminalia chebula extract on rumen biohydrogenation, ∆9-desaturase activity, CLA content and fatty acid composition in longissimus dorsi muscle of kids

Conjugated linoleic acid, a fatty acid found in milk fat and ruminant meat is one of the functional food components. Modifying fatty acid composition so as to increase CLA and other beneficial PUFA/MUFA level and reducing SFA levels might be a key to enhance the neutraceutical and therapeutic value of ruminant-derived food products. In the present experiment, the effect of supplementation of polyphenol rich Terminalia chebula plant extract at different concentrations (1.06g/kg and 3.18g/kg of body weight in T1 and T2 groups, respectively) was investigated on fatty acid composition of rumen fluid, plasma, intramuscular fat and Δ9-desaturase activity in longissimus dorsi muscle of crossbred kids. Total MUFA and PUFA content in muscle were enhanced by 25 and 35%, respectively, whereas SFA was reduced by 20% thereby improving the desaturation index. Δ9-desaturase activity also increased by 47% resulting in an enhancement of total CLA content (58.73%) in muscle.

Isolation of previously uncultured rumen bacteria by dilution to extinction using a new liquid culture medium

A new anaerobic medium that mimics the salts composition of rumen fluid was used in conjunction with a dilution method of liquid culture to isolate fermentative bacteria from the rumen of a grass-fed sheep. The aim was to inoculate a large number of culture tubes each with a mean of < 1 culturable cell, which should maximize the number of cultures that develop from a single bacterium. This minimizes the effort that has to be put into purifying the resultant cultures. Of 1000 tubes, 139 were growth positive. Of the 93 that were able to be subcultured, 54 (58%) appeared to be pure cultures. The phylogenetic placements of these 54 cultures, together with another 6 cultures obtained from a preliminary study, were determined. Using a criterion of < 93% 16S rRNA gene sequence identity to a previously named bacterium as a proxy for defining a new genus, 27 (45%) of the 60 cultures belonged to 14 potentially novel genera. Many of these had 16S rRNA genes that shared > 97% sequence identity to genes of uncultured bacteria detected in various gastrointestinal environments. This strategy has therefore allowed us to cultivate many novel rumen bacteria, opening the way to overcoming the lack of cultures of many of the groups detected using cultivation-independent methods.

Prediction of short chain fatty acids in rumen fluid using near infrared reflectance spectroscopy (NIRS)

Short chain fatty acids, produced from the fermentation of feedstuffs, form the ruminant’s primary energy source, as well as being precursors of glucose, protein and milk constituents (Dijkstra et al., 2000). The analysis of rumen fluid to estimate short chain fatty acids involves the addition of internal standards and analysis by gas chromatography. NIRS has been shown to have the potential to accurately and rapidly evaluate fresh silage chemical and biological parameters, including short chain fatty acids (Park et al., 1998). This study was undertaken to evaluate the potential of NIRS to accurately estimate the chemical composition of rumen fluid when a range of diets were fed to fistulated steers.

Ruminal degradation of protein of cocksfoot and perennial ryegrass as affected by various stages of growth and conservation methods

The behaviour of nitrogenous fractions in the rumen of sheep fed grasses at different vegetation stages and preserved by different methods was examined in this study. The measurements were made on four sheep fed forages. In Experiment 1, we used fresh cocksfoot cut at three stages of vegetation in the first growth stage (heading, first flower and full flower), two silages (one made with formic acid and the other without a preservative) and a first flower hay. In Experiment 2, we used fresh perennial ryegrass cut in the first growth stage (end of heading) and in the second growth stage at 7 week regrowth. A silage made with formic acid, two wrapped big bales harvested at 42% and 58% dry matter and a hay cut at the first growth stage (end of heading) were compared. The effective degradability of crude protein (DegN) estimated using the in situ method was lower (P < 0.05) with the latter vegetation stage for cocksfoot: 0.693 for the heading, 0.667 for the first flower, 0.597 for the full flower. For cocksfoot, the DegN of the silages was higher ( P< 0.05) for silage without additive (0.770) than for silage with formic acid (0.705) and higher than that of the fresh forage at first flower (0.667). The DegN of hay was markedly lower (0.537, P< 0.05) than that of the original fresh forage. The DegN of silage of perennial ryegrass (0.760) and wrapped big bales harvested at 42% DM (0.739) were higher ( P< 0.05) than that of fresh forage harvested at the end of heading (0.705). The DegN of wrapped big bales of perennial ryegrass harvested at 58% DM (0.667) and hay (0.536) were lower than those of the other forages ( P< 0.05). Whatever the forage studied, the concentration of to- tal nitrogen (tN), ammonia nitrogen (NH3-N) and non-ammonia nitrogen (NAN) were high 1 or 2 h after feeding and diminished rapidly up to 7ha fter feeding. Some of the solubilised nitrogen re- mained as proteins 1t o 2ha fter feeding for fresh forage harvested at various growth stages, but no protein was found in the rumen fluid after sheep were fed the silage (with or without preservative), wrapped big bales or hay. The proportion of dietary NAN flow (relative to ingested nitrogen) escap- ing rumen degradation was 5.8% to 10.1% for perennial ryegrass and 10.9% to 15% for cocksfoot. cocksfoot / perennial ryegrass / conservation method / vegetation stage / protein degradation / rumen fluid composition 245

On-Line Monitoring of Rumen Fluid in Milking Cows by Fibre Optics in Transmittance Mode Using the Longer NIR Region

A simple near infrared (NIR) on-line transmittance measurement method for rumen fluid in cows was developed and tested with a specially-designed fibre optic probe. NIR spectra in the long wavelength region from 1100 to 1860 nm were used for analysing the chemical composition of rumen fluid in two selected cows. Partial least squares (PLS) calibrations were developed for the components considered to be important indicators of rumen fluid composition. The change in rumen fluid composition as a function of feeding was followed by spectral readings. The results indicate that NIR has the potential for on-line measurement of rumen fluid composition by using these specially-designed fibre optics.

Degradation in the rumen of proteins from fresh lucerne forage in various stages of growth and conserved as silage or hay

The extent to which rumen soluble nitrogen can contribute to the intestinal flow is unknown. Therefore a study was carried out to simultaneously assess the dynamics of protein dis- appearance from dacron bags placed in the rumen and the amount of various N products (total nitro- gen (tN), ammonia nitrogen (NH3-N), non-ammonia nitrogen (NAN). Measurements were carried out on 4 sheep fed various lucerne forages. These forages included fresh lucerne cut at the vegetative or bud stage, fresh lucerne cut at the 6-week second growth stage and at stemmy regrowth stage. In addi- tion two silages made from lucerne at the bud stage, with or without formic acid were also given. The hay was dried on the ground in good weather. The effective degradability of nitrogen (DegN) estimated from the nylon bag procedure was lower (p < 0.05) with the latter vegetation stage (0.80 for vegeta- tive stage vs. 0.76 for bud stage). This value was 0.81 for the regrowth stage. The DegN of the silages was higher (p < 0.05) without additive (0.84) than with formic acid (0.80) and the DegN of the hay was markedly lower (0.66, p < 0.05) than with the original fresh forage. Whatever the forage studied, tN and NAN rumen fluid contents were high at 1 h or 2 h after feeding (from 0.458 mg .g -1 for hay to 0.813 mg.g -1 for fresh forage at the vegetative stage) and diminished rapidly up to 7 h after feeding except for the silages, for which the minimum content was observed 4 h after feeding. A part of the solubilised nitrogen remained as proteins at 1 h and 2 h after feeding for fresh lucerne at var- ious stages of harvesting (from 0.187 mg.g -1 to 0.221 mg.g -1 at 1 h) while no protein could be seen in the rumen fluid after feeding of sheep fed silage (with or without preservative) or hay. The part of NAN escaping rumen degradation and transiting with the rumen fluid represented 7 to 11% of the nitro- gen disappearing from the nylon bags placed in the rumen. There was little difference linked to the veg- etation stage of the forage or its mode of conservation in particular. This content remained high for hay while its effective degradability (0.66) was much lower than for other forages (from 0.76 to 0.84). lucerne / green forage / silages / hay / vegetation stage / protein degradation / rumen fluid composition