The use of high sugar grasses as a strategy to improve nitrogen utilization efficiency:A meta-analysis

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Evaluating lifetime nitrogen use efficiency of dairy cattle::A modelling approach

The increased nitrogen (N) use efficiency in cattle farming is proposed as a key action to improve N management and reduce the environmental impact of cattle farming systems. Most attention has been given to lactating cow nutrition, excluding the elements of fertility, disease, and the non-lactating animals within the herd. Therefore, the aim of the current study was to develop a herd-level simulation model incorporating these elements to assess dairy farm N use efficiency. We developed a cattle N use efficiency (CNE) model with six primary compartments: (i) heifer growth, (ii) heifer removal, (iii) pregnancy, (iv) cow removal, (v) disease and fertility, and (vi) milk production. The CNE model calculates N loss or gain for each compartment, and then calculates the lifetime N loss or gain taking into account the replacement rate (rep) and/or the corresponding number of lactations in a herd (Lact = 1/rep). Finally, three N use efficiencies were estimated: (i) ReplNE: replacement cattle N use efficiency, (ii) LactNE: lifetime N use efficiency for lactation, and (iii) LNE: lifetime N use efficiency. The sensitivity of the model to variation in farm- and animal-related input values was evaluated using Monte Carlo simulation. Values for a model dairy farm were used based on published data reflecting typical dairy farming practices in the United Kingdom. To assist reporting net values of main N outputs, a dairy herd of 100 lactating cows was modelled. Productive N outputs (1000s of kg) over the course of an animal's lifetime, partitioned into milk and meat, were dominated by milk production (89% of total N output). We estimated a mean ReplNE of 23.7%, affected most by the last stage of heifer growth. The Monte Carlo sensitivity analysis suggested that variation in time to first calving (T1stCal) might cause larger changes on ReplNE than variation in feed. The sensitivity analysis revealed a strong positive correlation between dietary oriented milk N use efficiency (MNE) and LactNE and LNE (r = 0.99 and 0.97 for LactNE and LNE, respectively). However, our study highlighted two other model variables that affected LNE. Variation in calving interval (CI; r = -0.15) and T1stCal (r = -0.15) may cause measurable reductions of overall LNE. The first is an indicator of lactating cattle fertility, and the second an indicator of replacement cattle growth and fertility efficiency. In conclusion, with the current study we provided a dairy cattle herd model that is sensitive in elements of diet, fertility and health. Lifetime N use efficiency of dairy cattle is dominated by MNE, but we detected specific non-diet related variables that affect ReplNE, LactNE and LNE

Reducing the environmental impact of the dairy farms through efficient use of nitrogen intake

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Climate mitigation by dairy intensification depends on intensive use of spared grassland

Milk and beef production cause 9% of global greenhouse gas (GHG) emissions. Previous life cycle assessment (LCA) studies have shown that dairy intensification reduces the carbon footprint of milk by increasing animal productivity and feed conversion efficiency. None of these studies simultaneously evaluated indirect GHG effects incurred via teleconnections with expansion of feed crop production and replacement suckler-beef production. We applied consequential LCA to incorporate these effects into GHG mitigation calculations for intensification scenarios among grazing-based dairy farms in an industrialized country (UK), in which milk production shifts from average to intensive farm typologies, involving higher milk yields per cow and more maize and concentrate feed in cattle diets. Attributional LCA indicated a reduction of up to 0.10 kg CO2e kg?1 milk following intensification, reflecting improved feed conversion efficiency. However, consequential LCA indicated that land use change associated with increased demand for maize and concentrate feed, plus additional suckler-beef production to replace reduced dairy-beef output, significantly increased GHG emissions following intensification. International displacement of replacement suckler-beef production to the ?global beef frontier? in Brazil resulted in small GHG savings for the UK GHG inventory, but contributed to a net increase in international GHG emissions equivalent to 0.63 kg CO2e kg?1 milk. Use of spared dairy grassland for intensive beef production can lead to net GHG mitigation by replacing extensive beef production, enabling afforestation on larger areas of lower quality grassland, or by avoiding expansion of international (Brazilian) beef production. We recommend that LCA boundaries are expanded when evaluating livestock intensification pathways, to avoid potentially misleading conclusions being drawn from ?snapshot? carbon footprints. We conclude that dairy intensification in industrialized countries can lead to significant international carbon leakage, and only achieves GHG mitigation when spared dairy grassland is used to intensify beef production, freeing up larger areas for afforestationpublishersversionPeer reviewe

Strategies to reduce nitrogen excretion from ruminants : targeting the rumen /

Esta tesis doctoral se llevó a cabo en el marco del proyecto financiado por la Unión Europea Rednex. El objetivo principal de la tesis fue utilizar tecnologías innovadoras aplicadas al rumen para proponer soluciones que pueden reducir la excreción de N en el ganado bovino lechero. Se llevaron a cabo cuatro estudios para evaluar: la espectroscopia de infrarrojo cercano como herramienta para mejorar la precisión en la formulación de raciones en la granja; el uso de anticuerpos policlonales (APs) contra las principal bacterias proteolíticas y desaminadoras en el rumen; y, el uso de compuestos de aceites esenciales (AE) como modificadores de la población microbiana responsable de la degradación de proteínas en el rumen y en forraje de raigrás durante el ensilaje. En el primer estudio, creamos una base de datos de 809 muestras distintas de alimentos frecuentemente utilizados en la alimentación de rumiantes. Parte de los alimentos se analizaron para la degradación de materia seca (MS) y proteína bruta (PB), y una parte más pequeña (n = 100) para la degradación de fibra neutro detergetnte (FND). Todas las muestras fueron escaneadas de 1,100 a 2,500 nm, utilizando un NIRSystems 5000, y se crearon calibraciones para todas las muestras (ALL), los forrajes (FF) y los no forrajes (NF). La degradación efectiva, las fracciones a y b de MS, PB y FND se predijeron bien, y mejoraron después de separación por grupos. La velocidad de la degradación de la MS, PB y FND no se predijo satisfactoriamente por ALL (r2 0,7). En el segundo estudio, evaluamos el efecto de la adición de compuestos activos de AE en la degradación de proteínas en ensilados de raigrás. Se prepararon microsilos (n = 74) en bolsas de poliéster con 2,0 kg de forraje fresco de raigrás. Los tratamientos fueron: timol (THY), eugenol (EUG), cinamaldehído (CIN), capsaicina (CAP) y carvacrol (CAR), a 0, 50, 500 y 2,000 mg / kg de forraje fresco. El pH del ensilaje fue mayor de lo esperado (5,5 a 6,6) y se atribuyó al bajo contenido de MS del forraje y la adición de los AE. La adición de THY, EUG y CAR a dosis altas (2,000 mg / kg) redujo la concentración de N-amoniacal, y la adición de CIN2.000 redujo la degradación de la proteína, resultando en silos con 9,7% más de N proteico real. Los compuestos de AE probados afectaron a la degradación de las proteínas y la desaminación del forraje de raigrás durante el ensilaje, pero la dosis efectiva fue demasiado alta para ser aplicado en la práctica. En el tercer estudio, se produjeron en conejos y probaron in vitro APs contra Prevotella ruminicola, Clostridium aminophilum y Peptostreptococcus anaerobius. Se llevaron dos experimentos a cabo utilizando la técnica de producción de gas e incubaciones in vitro durante 24 h, y ocho fermentadores de cultivo continuo, para probar los efectos de los APs en la fermentación ruminal a corto y largo plazo, respectivamente. Los tratamientos fueron: control (suero de animales no vacunados), APs contra P. ruminicola, C. aminophilum, P. anaerobius, y una mezcla de APs (1:1:1). La adición de APs no tuvo efecto sobre la fermentación ruminal ni a corto ni a largo plazo. En el cuarto estudio, se evaluaron los efectos de propil-propylthiosulfonato (PTSO), un compuesto organosulfurado estable del ajo, sobre la fermentación ruminal en un sistema de cultivo de doble flujo continuo. En el primer experimento, los tratamientos incluyeron un control negativo sin aditivo, un control positivo con monensina a 12 mg/l y dos dosis de PTSO a 30 mg/l (PTSO30) y 300 mg/l (PTSO300). La adición de PTSO30 no afectó a ninguna de las mediciones, y el PTSO300 disminuyo drásticamente la fermentación de nutrientes. El segundo experimento se llevó a cabo para probar dosis crecientes de PTSO (0, 50, 100 y 150 mg / l) sobre la fermentación microbiana ruminal. Los ácidos grasos volátiles totales y la proporción molar del propionato respondieron cuadráticamente con valores más altos en las dosis intermedias, y la digestibilidad de los nutrientes no se afectó. Los resultados sugieren el potencial de PTSO para modificar la fermentación del rumen en una dirección coherente con la mejora en la utilización de energía.The current PhD thesis was conducted within the framework of the European Union funded project RedNex. The main objective of the thesis was to use novel technologies that target the rumen to propose solutions that may reduce the N excretion from dairy cows. We conducted four studies testing: near infrared spectroscopy as a tool to provide better management for nutrient formulation at the farm; polyclonal antibodies against main proteolytic and deaminating bacteria in the rumen; and essential oil compounds as modifiers of microbial populations responsible for protein degradation in the rumen and ryegrass forage during ensiling. In the first study, we created a large database of 809 different feedstuffs frequently used in ruminant nutrition. Feedstuffs were analyzed for dry matter (DM) and crude protein (CP) degradation and a smaller part (n = 100) for neutral detergent fibre (NDF) degradation. All samples were scanned from 1,100 to 2,500 nm using a NIRSystems 5000, and calibrations were developed for all (ALL), and forages (FF) and no forage (NF) samples. The effective degradation, a and b fractions of DM, CP and NDF were well predicted and improved by group separation. The rate of degradation of DM, CP and NDF were not satisfactorily predicted for ALL (r2 0.7). In the second study, we evaluated the addition of essential oil (EO) compounds on ryegrass silage protein degradation. Microsilos (n = 74) were prepared in polyester bags with 2.0 kg of fresh ryegrass forage. Treatments were: thymol (THY), eugenol (EUG), cinnamaldehyde (CIN), capsaicin (CAP) and carvacrol (CAR), at 0, 50, 500 and 2,000 mg/kg of fresh forage. Silage pH was higher than expected (5.5 to 6.6) and was attributed to the low DM content of the forage and the addition of EO. The addition of THY, EUG and CAR at the high dose (2,000 mg/kg) reduced ammonia-N concentration, and the addition of CIN2000 had an overall effect on protein degradation resulting in silages with 9.7% higher true protein N. Tested EO compounds affected protein degradation and deamination of ryegrass forage during ensiling, but the effective dose was too high to be applied in practice. In the third study, we produced in rabbits and tested in vitro polyclonal antibodies (PAbs) against Prevotella ruminicola, Clostridium aminophilum and Peptostreptococcus anaerobius. Two experiments were conducted utilizing the modified gas production and the 24 h batch culture techniques, and 8 dual flow continuous culture fermenters to evaluate the addition of PAbs in short and long term ruminal fermentation, respectively. Treatments were: control (serum of non-immunized animals), PAbs against P. ruminicola, C. aminophilum, P. anaerobius, and a mix of PAbs (1:1:1). The addition of PAbs had no effect on ruminal fermentation in short term or in long term fermentation. In the fourth study, we evaluated, in two experiments, the effects of propyl-propylthiosulfonate (PTSO), a stable organosulfurate compound of garlic, on ruminal fermentation in a dual flow continuous culture system. In experiment 1, treatments included a negative control without additive, a positive control with monensin at 12 mg/l and two doses of PTSO at 30 (PTSO30) and 300 mg/l (PTSO300). The addition of PTSO30 did not affect any of the measurements, and PTSO300 decreased dramatically the fermentation of nutrients. Experiment 2 was conducted to test increasing doses of PTSO (0, 50, 100 and 150 mg/l) on rumen microbial fermentation. Total volatile fatty acids and propionate molar proportion responded quadratically with higher values in the intermediate doses, while digestibilities of nutrients were not affected. Results suggest the potential of PTSO to modify rumen fermentation in a direction consistent with better energy utilization

In vitro ruminal dry matter and neutral detergent fibre digestibility of common feedstuffs as affected by the addition of essential oils and their active compounds

The effects of essential oils (EO) and their active compounds (EOC) on dry matter digestibility and neutral detergent fibre digestibility (DMD and NDFD, respectively) are still not enough described since in vitro methods are limited. So, the aim of the study was to screen and compare the main effects of EO and EOC on short-term DMD and NDFD using the in vitro method. The addition of phenylpropanoid-rich cinnamon oil (CIN) and clove oil (CLO), terpenoid-rich thyme oil (THY) and oregano oil (ORG), and four EOC: cinnamaldehyde (CIN-C), eugenol (EUG), thymol (THY-C) and carvacrol (CAR) was studied at a dose of 0.5 mg ? l?1 of main active compound. Products were tested on four substrates: lucerne hay, soyabean meal, maize meal and a total mixed ration (TMR). Digestibility was determined at 4 and 24 h of fermentation. Both CIN and CIN-C increased NDFD4 of lucerne and maize meal, and decreased NDFD24 of soyabean meal; while CIN-C reduced NDF24 of TMR and CIN reduced DMD of soyabean at both examined hours. CLO and EUG decreased the NDFD24 of soyabean meal improving its DMD24. Also initial DMD of lucerne was increased by both these factors. Only CLO reduced NDFD24 of maize meal. Both THY and THY-C reduced DMD4 of soyabean meal; however only THY-C improved NDF4 of lucerne and reduced NDFD24 of soyabean meal and TMR. DMD24 of most substrates (except lucerne) was reduced by ORE, but not by CAR which improved NDFD4 of lucerne. The in vitro method was sensitive to variations in digestibility caused by EO and EOC, providing a promising approach for the incorporation of EO and EOC effects in systems for cattle diet formulationauthorsversionPeer reviewe