Grass Silage: Factors Affecting Efficiency of N Utilisation in Milk Production

Key points Low efficiency of N utilisation for milk production in cows fed grass silage-based diets is mainly due to excessive N losses in the rumen. The type and extent of in silo fermentation can alter the balance of absorbed nutrients. There is very little experimental evidence that the capture of N in the rumen can be improved by a better synchrony between energy and N release in the rumen. Nitrogen losses in the rumen can be reduced by decreasing the ratio between rumen degradable N and fermentable energy. Rapeseed meal has increased milk protein output more than isonitrogenous soybean meal supplementation, probably due to higher concentration of histidine in rapeseed protein. Efficiency of N utilisation for milk production is not necessarily lower for the grass silage based diets compared to other diets

Effects of sodium sulphate and potassium chloride fertilizers on the nutritive value of timothy grown on different soils

Third harvest samples from a pot experiment were analysed to study the effects of sodium (Na) (0, 200 and 400 mg dm-3 of soil in a single application as Na2SO4 . 10H2O) and potassium (K) application (0, 100 and 200 mg dm-3 applied at each harvest as KCl) on the nutritive value of timothy grown on three different soil types (clay, loam and organogenic soil). The effects of fertilization on concentrations of crude protein, neutral detergent fibre (NDF) and non-structural carbohydrates, although statistically significant, were relatively minor in absolute terms. Na applications increased and K applications decreased sulphur and phosphorus concentrations, the magnitude of which was dependent on soil type. The increase in sulphur concentration can be attributed to sulphate in Na-fertilizer. The effects of fertilizers on in vitro organic matter digestibility and the potential extent of dry matter (DM) and NDF digestibility were small. Digestion kinetic parameters estimated from fermentative gas production measured using a fully automated system were used in a rumen simulation model to estimate digestibility. Total gas volume and the rate of gas production from the rapidly digestible fraction were negatively correlated with timothy S and N concentrations. Na application had no effect, but K application increased true rumen DM digestibility, the effect being most profound on organogenic soil. The results suggest that Na application does not elicit substantial positive effects on the nutritive value of timothy which has often been reported for perennial ryegrass, but K application can improve the nutritive value of timothy grown on K deficient soil.;Tutkimuksen tavoitteena oli selvitettää natrium- ja kaliumlannoituksen vaikutusta timotein ravintoarvoon. Näytteet olivat Peltovuoren ja Yli-Hallan (1997) astiakokeesta, jossa selvitettiin Na- ja K-lannoituksen vaikutusta timotein Na, K,Ca ja Mg-pitoisuuteen ja satoon savi-, hieta- ja turvemaalla. Käytetyt ravinnemäärät olivat 0, 200 tai 400 mg Na l-1 kokeen alussa natriumsulfaattina ja 0, 100 tai 200 mg K 1-1 joka sadolle kaliumkloridina. Tähän tutkimukseen valittiin kolmannen sadon näytteet, koska niissä Na-pitoisuuden vaihtelu oli suurin (0,16-7,13 g kg-1). Vaikka timotei luetaan ns. natrofobisiin kasveihin, jotka ottavat huonosti natriumia versoihin, nousi timotein natriumpitoisuus huomattavasti. Na- ja K-lannoituksen vaikutusta timotein ravintoarvoon tutkittiin in vitro -kokein ja lisäksi määritettiin typpi, neutraalideterkenttikuitu (NDF), sokeri, rikki ja fosfori. Orgaanisen aineen in vitro -sulavuus määritettiin sellulaasimenetelmällä ja potentiaalinen kuiva-aineen ja NDF:n pötsisulavuus inkuboimalla näytettä 12 vrk nailonpussissa kahden lehmän pötsissä (in situ). Sulatuskinetiikan parametrit määritettiin mikrobikäymisen tuottaman kaasuntuotannon mittauksella ajan funktiona automaattisella mittauslaitteella, ja dynaamisen ja pötsimallin perusteella laskettiin potentiaalisesti sulavan kuiva-aineen pötsisulavuus ja kuiva-aineen todellinen pötsisulavuus. Lannoituksen vaikutus raakavalkuais-, NDF- ja sokeripitoisuuteen oli pieni. Na-lannoitus lisäsi hieman ja K-lannoitus vähensi typpipitoisuutta ja molemmat vähensivät laskennallista sokeripitoisuutta. NDF-pitoisuus nousi hieman Na-lannoituksella. Na-lannoitus lisäsi ja K-lannoitus vähensi rikki- ja fosforipitoisuutta vaikutuksen riippuessa maalajista. Na-lannoituksen vaikutukset orgaanisen aineen in vitro sulavuuteen sekä potentiaaliseen kuiva-aineen ja NDF:n pötsisulavuuteen olivat pieniä, vaikkakin tilastollisesti merkitseviä. Kokonaiskaasutuotanto ja nopeasti sulavan fraktion kaasutuotannon nopeus vähenivät, kun timotein typpi-, rikki-, kalsium-, magnesium-, fosfori- ja natriumpitoisuudet nousivat. Na-lannoituksella ei ollut vaikutusta sulatuskinetiikan parametreihin ja estimoituun potentiaalisesti sulavan kuiva-aineen pötsisulavuuteen tai kuiva-aineen todelliseen pötsisulavuuteen, kun taas K-lannoitus lisäsi hieman nopeasti sulavan fraktion kaasutuotannon nopeutta ja todellista kuiva-aineen pötsisulavuutta. Kaliumin vaikutus oli selvin turvemaalla. Maalajien välillä oli eroja kaasuntuotannon määrässä ja potentiaalisesti sulavan kuiva-aineen ja todellisessa kuiva-aineen pötsisulavuudessa, savimaa ruoho oli huonoiten ja turvemaan ruoho parhaiten sulavaa. Näiden tulosten mukaan Na-lannoituksella ei näytä olevan samanlaisia myönteistä vaikutusta timotein ravintoarvoon kuin brittiläistutkimuksissa on usein esitetty englannin raiheinällä, mutta K-lannoitus voi parantaa timotein ravintoarvoa K-puutteesta kärsivillä mailla

The Effect of Harvesting Strategy of Grass Silage on Milk Production

Timing of harvest in primary growth of grass is a major factor affecting D-value (digestible organic matter, g/kg DM) of silage and dry matter (DM) consumption and milk production of dairy cows (Rinne, 2000). The objective of this research was to investigate whether there is a similar pattern in regrowths of grass

Ruminal metabolism of ammonia N and rapeseed meal soluble N fraction

The present study was conducted to investigate ruminal N metabolism in dairy cows using N-15 labeled N sources [ammonia N (AN), soluble non-ammonia N (SNAN) from rapeseed meal, and insoluble nonammonia N (NAN) from rapeseed meal]. To describe the observed pattern of N-15 transactions in the rumen, dynamic compartmental models were developed. The experiment consisted of 3 experimental treatments allocated to 4 cows according to a changeover design. The results from 2 treatments (AN and rapeseed meal SNAN) are reported in this paper. Ammonia N and rapeseed SNAN, both labeled with N-15, were administered intraruminally. Rumen evacuations in combination with grab samples from the rumen contents were used to determine ruminal N pool sizes. The N-15-atom% excess was determined in N fractions of rumen digesta samples that were distributed between 0 and 82 h after dosing. For the AN treatment, a 2-compartment model was developed to describe the observed pattern in N-15-atom% excess pool sizes of AN and bacterial NJ and to estimate kinetic parameters of ruminal N-15 transactions. For the SNAN treatment, an additional compartment of SNAN was included in the model. Model simulations were used to estimate N fluxes in the rumen. Both models described the observed pattern of N-15-atom% excess pool sizes accurately, based on small residuals between observed and predicted values. Immediate increases in N-15-atom% excess of bacterial N with AN treatment suggested that microbes absorbed AN from extracellular pools rapidly to maintain sufficient intracellular concentrations. Proportionally 0.69 of the AN dose was recovered as NAN flow from the rumen. A rapid disappearance of labeled SNAN from rumen fluid and appearance in bacterial N pool indicated that, proportionally, 0.56 of SNAN was immediately either adsorbed to bacterial cell surfaces or taken up to intracellular pools. Immediate uptake of labeled SNAN was greater than that of AN (proportionally 0.56 vs. 0.16 of the dose). Degradation rate of SNAN to AN was relatively slow (0.46/h), but only 0.08 of the SNAN dose was estimated to escape ruminal degradation because of rapid uptake by the bacteria. Overall, losses of the N-15 dose as AN absorption and outflow from the rumen were higher (P <0.01) for the AN than the SNAN treatment (0.31 and 0.11 of the dose, respectively). Consequently, recovery as NAN flow was greater for SNAN than for AN treatment (0.89 vs. 0.69 of the dose). Estimated rate of bacterial N recycling to AN was on average 0.006/h, which suggests that N losses due to intraruminal recycling are small in dairy cows fed at high intake levels. We conclude that SNAN isolated from rapeseed meal had better ruminal N utilization efficiency than AN, as indicated by smaller rurninal N losses as AN (0.11 vs. 0.31 of the dose) and greater bacterial N flow (0.81 vs. 0.69 of the dose). Furthermore, the current findings indicate that rapid adsorption of soluble proteins to bacterial cells plays an important role in ruminal N metabolism.Peer reviewe

Ruminal metabolism of ammonia N and rapeseed meal soluble N fraction

The present study was conducted to investigate ruminal N metabolism in dairy cows using N-15 labeled N sources [ammonia N (AN), soluble non-ammonia N (SNAN) from rapeseed meal, and insoluble nonammonia N (NAN) from rapeseed meal]. To describe the observed pattern of N-15 transactions in the rumen, dynamic compartmental models were developed. The experiment consisted of 3 experimental treatments allocated to 4 cows according to a changeover design. The results from 2 treatments (AN and rapeseed meal SNAN) are reported in this paper. Ammonia N and rapeseed SNAN, both labeled with N-15, were administered intraruminally. Rumen evacuations in combination with grab samples from the rumen contents were used to determine ruminal N pool sizes. The N-15-atom% excess was determined in N fractions of rumen digesta samples that were distributed between 0 and 82 h after dosing. For the AN treatment, a 2-compartment model was developed to describe the observed pattern in N-15-atom% excess pool sizes of AN and bacterial NJ and to estimate kinetic parameters of ruminal N-15 transactions. For the SNAN treatment, an additional compartment of SNAN was included in the model. Model simulations were used to estimate N fluxes in the rumen. Both models described the observed pattern of N-15-atom% excess pool sizes accurately, based on small residuals between observed and predicted values. Immediate increases in N-15-atom% excess of bacterial N with AN treatment suggested that microbes absorbed AN from extracellular pools rapidly to maintain sufficient intracellular concentrations. Proportionally 0.69 of the AN dose was recovered as NAN flow from the rumen. A rapid disappearance of labeled SNAN from rumen fluid and appearance in bacterial N pool indicated that, proportionally, 0.56 of SNAN was immediately either adsorbed to bacterial cell surfaces or taken up to intracellular pools. Immediate uptake of labeled SNAN was greater than that of AN (proportionally 0.56 vs. 0.16 of the dose). Degradation rate of SNAN to AN was relatively slow (0.46/h), but only 0.08 of the SNAN dose was estimated to escape ruminal degradation because of rapid uptake by the bacteria. Overall, losses of the N-15 dose as AN absorption and outflow from the rumen were higher (P <0.01) for the AN than the SNAN treatment (0.31 and 0.11 of the dose, respectively). Consequently, recovery as NAN flow was greater for SNAN than for AN treatment (0.89 vs. 0.69 of the dose). Estimated rate of bacterial N recycling to AN was on average 0.006/h, which suggests that N losses due to intraruminal recycling are small in dairy cows fed at high intake levels. We conclude that SNAN isolated from rapeseed meal had better ruminal N utilization efficiency than AN, as indicated by smaller rurninal N losses as AN (0.11 vs. 0.31 of the dose) and greater bacterial N flow (0.81 vs. 0.69 of the dose). Furthermore, the current findings indicate that rapid adsorption of soluble proteins to bacterial cells plays an important role in ruminal N metabolism.Peer reviewe

The Effect of Harvesting Strategy of Grass Silage on Milk Production

Timing of harvest in primary growth of grass is a major factor affecting D-value (digestible organic matter, g/kg DM) of silage and dry matter (DM) consumption and milk production of dairy cows (Rinne, 2000). The objective of this research was to investigate whether there is a similar pattern in regrowths of grass

Prediction of Indigestible NDF Content of Grass and Legume Silages by NIRS

The future feed evaluation systems based on mechanistic digestion models require reliable estimates of forage digestible and indigestible NDF content (DNDF and INDF). The objective of this study was to examine the potential of near infrared reflectance spectroscopy (NIRS) in predicting INDF content of grass and legume silages

Digestibility Estimates Based on a Grass Growth Model Are Distributed via Internet to Finnish Farmers

Optimising the harvesting time of grass in primary growth is difficult under Finnish climatic conditions, because the digestibility of grass decreases on average by 0.5 percentage units daily. We constructed a model based on cumulative temperature and geographical location which estimates the digestibility of grass. This model is used to produce estimates utilising real time weather information. The estimates are presented as a map, which is revised daily. Farmers have free access to the maps via Internet

Development of a framework for radiographer online clinical education (FORCE): the specifc strand of nuclear medicine within this european project

The overall aim of the FORCE project is to develop virtual web-based learning resources where Radiography undergraduates can engage in interactive, problem-based development of radiographic knowledge, ability and professional awareness. This European-funded project is internally divided in three diferent strands (Radiology Diagnostic Imaging, Radiotherapy and Nuclear Medicine). The aim of this presentation is to present the global project, mainly focusing developments, achievements and challenges within the Nuclear Medicine specifc strand.info:eu-repo/semantics/publishedVersio

The effects of energy metabolism variables on feed efficiency in respiration chamber studies with lactating dairy cows

The objective of the present study was to investigate factors related to variation in feed efficiency (FE) among cows. Data included 841 cow/period observations from 31 energy metabolism studies assembled across 3 research stations. The cows were categorized into low-, medium-, and high-FE groups according to residual feed intake (RFI), residual energy-corrected milk (RECM), and feed conversion efficiency (FCE). Mixed model regression was conducted to identify differences among the efficiency groups in animal and energy metabolism traits. Partial regression coefficients of both RFI and RECM agreed with published energy requirements more closely than cofficients derived from production experiments. Within RFI groups, efficient (Low-RFI) cows ate less, had a higher digestibility, produced less methane (CH4) and heat, and had a higher efficiency of metabolizable energy (ME) utilization for milk production. High-RECM (most efficient) cows produced 6.0 kg/d more of energy-corrected milk (ECM) than their Low-RECM (least efficient) contemporaries at the same feed intake. They had a higher digestibility, produced less CH4 and heat, and had a higher efficiency of ME utilization for milk production. The contributions of improved digestibility, reduced CH4, and reduced urinary energy losses to increased ME intake at the same feed intake were 84, 12, and 4%, respectively. For both RFI and RECM analysis, increased metabolizability contributed to approximately 35% improved FE, with the remaining 65% attributed to the greater efficiency of utilization of ME. The analysis within RECM groups suggested that the difference in ME utilization was mainly due to the higher maintenance requirement of Low-RECM cows compared with Medium- and High-RECM cows, whereas the difference between Medium- and High-RECM cows resulted mainly from the higher efficiency of ME utilization for milk production in High-RECM cows. The main difference within FCE (ECM/DMI) categories was a greater (8.2 kg/d) ECM yield at the expense of mobilization in High-FCE cows compared with Low-FCE cows. Methane intensity (CH4/ECM) was lower for efficient cows than for inefficient cows. The results indicated that RFI and RECM are different traits. We concluded that there is considerable variation in FE among cows that is not related to dilution of maintenance requirement or nutrient partitioning. Improving FE is a sustainable approach to reduce CH4 production per unit of product, and at the same time improve the economics of milk production.202