Christopher K Reynolds

University of Reading · School of Agriculture, Policy and Development

Automated measurements of the ratio of concentrations of methane and carbon dioxide, [CH4]:[CO2], in breath from individual animals (the so-called "Sniffer-technique") and estimated CO2 production can be used to estimate CH4 production, provided that CO2 production can be reliably calculated. This would allow CH4 production from individual cows to...

Methane (CH 4 ) emissions from ruminants are of a significant environmental concern, necessitating accurate prediction for emission inventories. Existing models rely solely on dietary and host animal-related data, ignoring the predicting power of rumen microbiota, the source of CH 4 . To address this limitation, we developed novel CH 4 prediction m...

Detecting bovine tuberculosis (bTB) primarily relies on the tuberculin skin test, requiring two separate animal handling events with a period of incubation time (normally 3 days) between them. Here, we present the use of liquid atmospheric pressure (LAP)-MALDI for the identification of bTB infection, employing a three-class prediction model that wa...

This study investigated the effect of feeding seaweed (Ascophyllum nodosum) to dairy cows on milk mineral concentrations, feed-to-milk mineral transfer efficiencies and hematological parameters. Lactating Holstein cows (n = 46) were allocated to one of 2 diets (n = 23 each): (i) control (CON; without seaweed), and (ii) seaweed (SWD; replacing 330 g...

Recycled bioresources (biosolids, compost-like-output, meat and bonemeal ash, poultry litter ash, paper sludge ash) were added to the feed of dairy cattle to simulate incidental ingestion from agricultural utilisation, to investigate the transfer of organic contaminants from the ingested materials to milk. The bioresources were blended with a loamy...

Enteric methane (CH4) emissions from sheep contribute to global greenhouse gas emissions from livestock. However, as already available for dairy and beef cattle, empirical models are needed to predict CH4 emissions from sheep for accounting purposes. The objectives of this study were to: 1) collate an intercontinental database of enteric CH4 emissi...

An isotope dilution model for partitioning phenylalanine and tyrosine uptake by the liver of the lactating dairy cow is constructed and solved in the steady state. An original ten-pool model is adopted and solved by cleaving it into two five-pool sub-models, one representing phenylalanine and the other tyrosine. If assumptions are made, model solut...

Given the lack of research regarding the effect of microalgal supplementation in dairy cows on milk mineral concentrations, this study investigated the effect of feeding different protein supplements in dairy cow diets on milk, feces, and blood plasma mineral concentrations , associated milk and blood plasma transfer efficiencies, and apparent dige...

Manure nitrogen (N) from cattle contributes to nitrous oxide and ammonia emissions and nitrate leaching. Measurement of manure N outputs on dairy farms is laborious, expensive, and impractical at large scales; therefore, models are needed to predict N excreted in urine and feces. Building robust prediction models requires extensive data from animal...

Decoupling nitrous oxide (N2O) emissions from grassland production systems will be fundamental to meeting legislative greenhouse gas (GHG) reduction targets and thus mitigating climate change. In recent years, there has been increased uptake of multi-species swards in intensive production systems due to the associated multi-functional benefits incl...

• We aimed to establish common guidelines for experimental studies with cattle. • A book on “Methods in cattle physiology and behaviour research” was published. • The book is designed as an open-access living handbook and is open to everyone. • Citing the book saves space and avoids repetitions in scientific journals. • Referencing guidelines reduc...

The excretion of nitrogen (N) in faeces and urine from beef cattle contributes to atmospheric pollution through greenhouse gas and ammonia emissions and eutrophication of land and aquatic habitats through excessive N deposition and nitrate leaching to groundwater. As N excretion by beef cattle is rarely measured directly, it is important to accurat...

Measurement of enteric methane is expensive and not practical in most farms. Reliable prediction models have been developed recently for dairy and beef cattle based on intercontinental databases; however, equivalent sheep models are not yet available. This study aimed to: 1) collate an intercontinental database from individual sheep; 2) identify th...

Significance Agricultural methane emissions must be decreased by 11 to 30% of the 2010 level by 2030 and by 24 to 47% by 2050 to meet the 1.5 °C target. We identified three strategies to decrease product-based methane emissions while increasing animal productivity and five strategies to decrease absolute methane emissions without reducing animal pr...

Phenylalanine (PHE) and to a lesser extent TYR are two commonly used amino acid tracers for measuring protein metabolism in a variety of species and tissues. The model examined in this paper was developed to resolve trans-organ and stable isotope dilution data collected from experiments with lactating dairy cows using these tracers. Two methods of...

Estimating the efficiency of N utilization for milk production (MNE) of individual cows at a large scale is difficult, particularly because of the cost of measuring feed intake. Nitrogen isotopic discrimination (Δ¹⁵N) between the animal (milk, plasma, or tissues) and its diet has been proposed as a biomarker of the efficiency of N utilization in a...

Our objective was to determine the effects of chemical structure, amount, and site of infusion of long‐chain fatty acids (LCFA) in lactating dairy cows. Six multiparous Holstein cows were used in a 6 × 6 Latin square design with 21‐d periods. During d 1 to 14, 250 g/d of LCFA and during d 15 to 21, 500 g/d of LCFA were infused continuously into eit...

Large-scale population screening for early and accurate detection of disease is a key objective for future diagnostics. Ideally, diagnostic tests that achieve this goal are also cost-effective, fast and easily adaptable to new diseases with the potential of multiplexing. Mass spectrometry (MS), particularly MALDI MS profiling, has been explored for...

CONTEXT Identifying the determinants of phosphorus (P) balance and use efficiency (PUE) is critical to improving the sustainability of dairy farming in countries operating diverse dairy farming systems because each system contributes to eutrophication through different pathways. However, information about P balance and PUE across diverse dairy farm...

The objective was to determine the effect of dietary ratio of neutral detergent fibre (aNDFom) to starch within diets differing in grass to maize silage ratio on rumen function, diet digestion, serum haptoglobin, and production of lactating dairy cows. Four isonitrogenous diets were formulated with a forage to concentrate ratio of 50:50, with the f...

In a field experiment, annual nitrous oxide (N2O) emissions and grassland yield were measured across different plant communities, comprising systematically varying combinations of monocultures and mixtures of three functional groups (FG): grasses (Lolium perenne, Phleum pratense), legumes (Trifolium pratense, Trifolium repens) and herbs (Cichorium...

Animal proteins are naturally enriched in 15N relative to the consumed diet and the 15N enrichment of animal proteins over the diet (Δ15N) has been recently shown to capture the between-animal variation in N use efficiency (NUE). The aim of this study was to evaluate the performance of a previous model to predict between-animal variability in NUE f...

The accurate and timely assessment of pasture quantity and quality (i.e., nutritive characteristics) is vital for effective pasture management. Remotely sensed data can be used to predict pasture quantity and quality. This study investigated the ability of Sentinel-2 multispectral bands, convolved from proximal hyperspectral data, in predicting var...

This chapter examines the impact of improving feed efficiency on the environmental impact of livestock production. It starts by discussing the relation between greenhouse gases and dairy production, highlighting how important it is to the dairy sector to find ways of decreasing greenhouse gas output. The chapter then moves on to discuss the origins...

Minimising phosphorus (P) feeding to dairy cows can reduce feed costs and minimise water pollution without impairing animal performance. This study aimed to determine current P feeding practices and identify the barriers to and motivators for minimising P feeding on dairy farms, using Great Britain (GB) dairy farming as an example of diverse system...

Accurately predicting nitrogen (N) outputs in manure, urine and faeces from beef cattle is crucial for the realistic assessment of the environmental footprint of beef production and the development of sustainable N mitigation strategies. This study aimed to develop and validate equations for N outputs in manure, urine and faeces for animals under d...

Diet composition and intake are the main determinants of nitrogen (N) use efficiency (NUE) in beef cattle. Accounting for the interactions and comparative effects of different feedstuff types on NUE and N losses in urine and faeces can inform the development of financially and environmentally sustainable feeding protocols for beef cattle. This stud...

Growing interest in food quality and traceability by regulators as well as consumers demands advances in more rapid, versatile and cost-effective analytical methods. Milk, as most food matrices, is a heterogeneous mixture composed of metabolites, lipids and proteins. One of the major challenges is to have simultaneous, quantitative detection (profi...

Ruminant livestock enteric fermentation contributes approximately one-third of the global anthropogenic methane (CH 4 ) emissions and is projected to increase significantly to meet the increasing demand for animal-sourced protein. Methane, a short-lived greenhouse gas, needs to be reduced -24 to -47% by 2050 relative to 2010 to meet the 2.0°C targe...

The digestive health of cows is one of the primary factors that determine their well-being and productivity. Under- and over-feeding are both commonplace in the beef and dairy industry; leading to welfare issues, negative environmental impacts, and economic losses. Unfortunately, digestive health is difficult for farmers to routinely monitor in lar...

Agricultural intensification within forage systems has reduced grassland floral diversity by promoting ryegrass ( Lolium spp. ), damaging soil functionality which underpins critical ecosystem services. Diverse forage mixtures may enhance environmental benefits of pastures by decreasing nutrient leaching, increasing soil carbon storage, and with leg...

The anatomy and digestive and absorptive function of the small intestine of lactating ruminants, particularly the dairy cow, include a specialized anatomy and microflora to digest a variety of fibrous feedstuffs, in both pre-gastric and post-gastric fermentation structures. The rumen microbes ferment most carbohydrate to volatile fatty acids, which...

A liquid matrix-assisted laser desorption/ionization (liquid MALDI) method has been developed for high-throughput atmospheric pressure (AP) mass spectrometry (MS) analysis of the molecular content of crude bioliquids for disease diagnostics. The presented method is rapid and highly robust, enabling its application in environments where speed and lo...

Nitrogen is a component of essential nutrients critical for the productivity of ruminants. If excreted in excess, N is also an important environmental pollutant contributing to acid deposition, eutrophication, human respiratory problems, and climate change. The complex microbial metabolic activity in the rumen and the effect on subsequent processes...

Enteric methane (CH4) production attributable to beef cattle contributes to global greenhouse gas emissions. Reliably estimating this contribution requires extensive CH4 emission data from beef cattle under different management conditions worldwide. The objectives were to: 1) predict CH4 production (g d−1 animal−1), yield [g (kg dry matter intake;...

The objective of this study was to evaluate the performance of existing models predicting enteric methane (CH⁠4) emissions, using a large database (3183 individual data from 103 in vivo studies on dairy and beef cattle, sheep and goats fed diets from different countries). The impacts of dietary strategies to reduce CH⁠4 emissions, and of diet quali...

Beef cattle production is valuable to food security, contributing meat of high nutritional value. However, beef cattle are rather inefficient in utilising dietary nitrogen (N), thus excreting substantial amounts of N in their urine and faeces and imposing an environmental burden. The aim of this study was to evaluate the main dietary factors affect...

Our aim was to evaluate the effects of ryegrass silage (GS) chop length (CL) and ratio of GS to corn silage (CS) in the diet on digestibility and blood metabolites of dairy cows. Ryegrass was chopped at 2 mean CL (short; 31 and long; 44 mm) and mixed with CS (GS:CS) at 100:0 or 40:60 ratio (dry matter [DM] basis) of the forage fed at 54% of DM in i...

The measurement of lignin content in ruminant diet and faecal samples is important for digestibility studies, but it is typically time consuming and costly. The work reported involved correlation of traditional wet chemistry data with that from three rapid instrumental techniques, Fourier Transform Infrared spectroscopy (FTIR), Conventional Thermog...

Isoenergetic replacement of dietary saturated fatty acids (SFA) with cis-monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) can reduce cardiovascular disease risk. Supplementing dairy cow diets with plant oils lowers milk fat SFA concentrations. However, this feeding strategy can also increase milk fat trans fatty acids (FA)...

A large proportion of the global land surface is covered by pasture. The advent of the Sentinel satellites program provides free datasets with good spatiotemporal resolution that can be a valuable source of information for monitoring pasture resources. We combined optical remote sensing data (proximal hyperspectral and Sentinel 2A) with a radiative...

The purpose of the present study was, firstly, to examine current practice for the agronomy of grass-clover mixed swards used for silage-making in the UK, and secondly, to develop and validate a Near Infra-Red Reflectance Spectroscopy (NIRS) equation capable of predicting clover concentration (CC) in undried and unmilled grass-clover silage samples...

The particle size of the forage has been proposed as a key factor to ensure a healthy rumen function and maintain dairy cow performance, but little work has been conducted on ryegrass silage (GS). To determine the effect of chop length of GS and GS:maize silage (MS) ratio on the performance, reticular pH, metabolism and eating behaviour of dairy co...

Enteric methane (CH4) production from cattle contributes to global greenhouse gas emissions. Measurement of enteric CH4 is complex, expensive and impractical at large scales; therefore, models are commonly used to predict CH4 production. However, building robust prediction models requires extensive data from animals under different management syste...

It is known that supplementing dairy cow diets with full-fat oilseeds can be used as a strategy to mitigate methane emissions, through their action on rumen fermentation. However, direct comparisons of the effect of different oil sources are very few, as are studies implementing supplementation levels that reflect what is commonly fed on commercial...

Ruminant production systems are important contributors to anthropogenic methane (CH4) emissions, but there are large uncertainties in national and global livestock CH4 inventories. Sources of uncertainty in enteric CH4 emissions include animal inventories, feed dry matter intake (DMI), ingredient and chemical composition of the diets, and CH4 emiss...

In the last decade, various applications of gaseous exchange measurements have been developed to quantify the production or consumption of particular gases by animals. Notably, booming research into methane emissions has led to an expansion of the number of facilities in which such measurements are made. Results of a ring test calibration of respir...

Highlights • We develop a model to resolve trans-liver and isotope data on PHE and TYR. • It progresses earlier work in J Theor Biol on tracer LEU across the liver. • The model was effective in providing information on the partition of PHE and TYR. • It could be a useful component of a system for describing whole-animal AA metabolism. Abstract An...

The purpose of this study was to ascertain whether Near Infra-Red Reflectance Spectroscopy (NIRS) prediction equations calibrated on grass silage samples, could accurately predict the chemical composition of mixed grass-clover silage samples, and furthermore, to develop and calibrate new grass-clover equations should the grass-based equations be in...

Ongoing improvements in the genetic merit of United Kingdom (UK) dairy cows as well as changes in the national milk market will increase awareness of and provide focus on the importance of balanced nutrition, particularly with respect to energy and protein. Within the UK, energy is rationed according to the metabolizable energy (ME) scheme, propose...

The objectives of the study were (1) to test whether 6 h of feed deprivation followed by refeeding induces an acidosis challenge in dairy cattle and (2) to quantify the acidosis challenge mitigation potential of increased alfalfa silage concentration in the diet. Alfalfa silage constituted either 25 or 75% of forage dry matter (DM) replacing corn s...

Dear Editor: In the last decade, various applications of gaseous exchange measurements have been developed for quantifying the production or consumption of particular gases by animals. Notably, booming research into methane emissions has led to an expansion of the number of facilities in which such measurements are made. Recent research by Gardine...

Cattle fed forage based diets often absorb a high proportion of dietary N as ammonia (NH3N) and this must be detoxified in the liver to urea. It has been suggested that this process utilises both energy and amino acids and may contribute to the lower efficiency of utilisation of dietary nitrogen and energy observed in forage fed ruminants (Fitch et...

Feeding fat to increase metabolisable energy content of lactation rations for dairy cows is now a common practice. It generally increases milk yield but decreases milk protein concentration. In North America whole oil seeds (cotton seeds, soya beans, sunflower seeds, etc.) containing high levels of linoleic acid are often fed as a fat source in a t...

Lameness in the dairy cow not only causes major financial loss but also has serious welfare implications. Both environmental and nutritional factors have been implicated in its occurrence, which is commonly observed as laminitis, white line disease and sole ulcers, which are disorders of the corium. The aim of the current study was to examine the e...

Fat is often fed to lactating dairy cows to provide supplemental metabolizable energy and increase milk yield. Commercial fat sources are typically processed to render them more inert in the rumen, but whole oil seeds also represent an effective fat source for lactation rations. In a previous study (Reynolds et al. , 1998), we fed lactating dairy c...

Milk protein concentration can be influenced by dietary manipulation, but the efficiency of amino acid transfer into milk and the predictability of the response are both poor. Previous reports from this research group have demonstrated that milk protein concentration can be repeatedly increased in response to vascular infusions of essential amino a...

Studies involving infusion of stable isotope labelled peptides have shown that the mammary gland has the ability to utilise peptide-derived AA for milk protein synthesis (Backwell et al ., 1994a) and that peptides may be involved in the supply of phenylalanine to the mammary gland in vivo (Backwell et al ., 1994b). The aim of the present experiment...

Although high genetic merit dairy cows are capable of peak yields in excess of 50 kg per day these are seldom maintained primarily due to an inability to satisfy energy requirements. Fats and oils are often incorporated into rations as a means of increasing dietary energy content. However, unless included at relatively low levels or in a protected...

Whole oil seeds represent an alternative to many commercial rumen-protected fat sources as energy supplements in rations for lactating dairy cows. Rumen protection reduces the potential for negative effects of unsaturated fatty acids on fibre digestion, but the structure of many whole oil seeds are thought to reduce the reactivity of their fat in t...

Rumen acidosis is a problem in many production systems where readily fermentable concentrates are fed. Although acidosis is more common as a subclinical condition that can impair fibre digestion, numerous factors can precipitate the clinical disorder. The objective of the present study was to begin development of a model of acidosis using a rumen s...

Non-additivity occurs when the nutritive value of a mixture of feedstuffs differs from that of the sum of its components. It is most commonly observed when one dietary constituent influences, either positively or negatively, the apparent digestibility of another under conditions where components such as nitrogen and sulphur are non-limiting. In gen...

Cow genetics, forage supply and quality, and feeding systems are relatively fixed in the short term. Therefore, it is important to establish the effect on intake and performance of a range of nutritional strategies. The purpose of the current study was to determine the effects on milk production and composition of nutritional strategies designed to...

As part of the Global Network project, led by Alex Hristov (Penn State, USA), a dataset containing more than 6,000 individual animal data on methane (CH4) and ammonia emissions, and other metadata (intake, diet composition, animal parameters) from ruminants was built. A sub-dataset (from 11 partners) was used to compare the performances of extant p...

The objective of this study was to investigate whether higher lucerne (Medicago sativa; alfalfa) silage inclusion rate and longer lucerne chop length improves rumen function through increased provision of physically effective fiber, when included in a maize and lucerne silage-based total mixed ration. Diets were formulated to contain a 50:50 forage...

The objective was to assess the effects of inclusion rate and chop length of lucerne silage, when fed in a total mixed ration (TMR), on milk yield, dry matter (DM) intake (DMI) and digestion in dairy cows. Diets were formulated to contain a 50 : 50 ratio of forage : concentrate (DM basis) and to be isonitrogenous (170 g/kg CP). The forage portion o...

Interest is growing in developing integrated postabsorptive metabolism models for dairy cattle. An integral part of linking a multi-organ postabsorptive model is the prediction of nutrient fluxes between organs, and thus blood flow. The purpose of this paper was to use a multivariate meta-analysis approach to model portal blood flow (PORBF) and hep...

Ruminant husbandry is a major source of anthropogenic greenhouse gases (GHG). Filling knowledge gaps and providing expert recommendation are important for defining future research priorities, improving methodologies and establishing science-based GHG mitigation solutions to government and non-governmental organisations, advisory/extension networks,...

Strategies to mitigate greenhouse gas emissions from dairy cattle are unlikely to be adopted if production or profitability is reduced. The primary objective of this study was to examine the effects of high maize silage (MS) versus high grass silage (GS) diets, without or with added neutral detergent fiber (NDF) on milk production and methane emiss...

Enteric methane (CH 4 ) production is a side-effect of herbivore digestion, but it is unknown whether CH 4 itself influences digestive physiology. We investigated the effect of adding CH 4 to, or reducing it in, the reticulorumen (RR) in a 4×4 Latin square experiment with rumen-fistulated, non-lactating cows, with four treatments: (i) control, (ii)...

Supplementing dairy cow diets with oilseed preparations has been shown to replace milk saturated fatty acids (SFA) with mono- and/or polyunsaturated fatty acids (MUFA, PUFA), which may reduce risk factors associated with cardio-metabolic diseases in humans consuming milk and dairy products. Previous studies demonstrating this are largely detailed,...

In vitro fermentation techniques (IVFT) have been widely used to evaluate the nutritive value of feeds for ruminants and in the last decade to assess the effect of different nutritional strategies on methane (CH4) production. However, many technical factors may influence the results obtained. The present review has been prepared by the ‘Global Netw...

A range of wastes representative of materials currently applied, or with future potential to be applied, to agricultural land in the UK as fertilisers and soil improvers or used as animal bedding in livestock production, were investigated. In addition to full physico-chemical characterization, the materials were analysed for a suite of priority org...

Changes in diet carbohydrate amount and type (i.e., starch vs. fiber) and dietary oil supplements can affect ruminant methane emissions. Our objectives were to measure methane emissions, whole-tract digestibility, and energy and nitrogen utilization from growing dairy cattle at 2 body weight (BW) ranges, fed diets containing either high maize silag...