Deirdre Hennessy

University College Cork | UCC · School of Biological, Earth & Environmental Sciences

There is an increasing consumer desire for pasture-derived dairy products, as outdoor pasture-based feeding systems are perceived as a natural environment for animals. Despite this, the number of grazing animals globally has declined as a result of the higher milk yields achieved by indoor, total mixed ration feeding systems, in addition to the cha...

The objective of this study was to examine the impact of increasing proportions of grazed pasture in the diet on the composition, quality, and functionality of bovine milk across a full lactation. Fifty-four spring-calving cows were randomly assigned to 1 of 3 groups (n = 18), blocked on the basis of mean calving date (February 15, 2020 ± 0.8 d), p...

The composition of seasonal pasture-produced milk is influenced by stage of lactation, animal genetics, and nutrition, which affects milk nutritional profile and processing characteristics. The objective was to study the effect of lactation stage (early, mid, and late lactation) and diet on milk composition in an Irish spring calving dairy research...

In grassland ecosystems, it is well known that increasing plant species diversity can improve ecosystem functions (i.e., ecosystem responses), for example, by increasing productivity and reducing weed invasion. Diversity-Interactions models use species proportions and their interactions as predictors in a regression framework to assess biodiversity...

Technology is becoming embedded in different aspects of agriculture. Specifically, automation of the milking process within dairy production systems represents fundamental change for the operator, the cow herd and indeed the whole farm operation. Adoption of automatic milking requires new thinking for the traditional tasks of feeding, milking and m...

In pasture-based dairy production systems, identifying the appropriate stocking rate (SR; cows/ha) based on the farm grass growth is a key strategic decision for driving the overall farm business. This paper investigates a number of scenarios examining the effects of SR (2–3 cows/ha (0.25 unit changes)), annual nitrogen (N) fertilizer application r...

Sward species composition estimation is a tedious one. Herbage must be collected in the field, manually separated into components, dried and weighed to estimate species composition. Deep learning approaches using neural networks have been used in previous work to propose faster and more cost efficient alternatives to this process by estimating the...

Aroma-active compounds in raw bovine milk produced from cows fed perennial ryegrass (GRS) or total mixed ration (TMR) consisting of grass silage, maize silage, and concentrates were identified by direct immersion sorptive extraction (DI Hi-Sorb), coupled with gas-chromatography-mass spectrometry and olfactometry using odour intensity (OI) and aroma...

Good rumen function, which is largely influenced by the diet of the cow, is essential to optimise animal performance. This study, conducted over the course of a full lactation in a spring-calving milk production system, compared the rumen function and milk production of cows offered one of three dietary treatments: (1) Cows grazing grass-only sward...

In the last 60 yr Irish grassland production has increased substantially in no small part due to high-quality fundamental grassland research. Increased production from grassland has arisen from improved understanding (research and practice) of soil and plant nutrition, plant physiology and variety improvement, while improved understanding of feed e...

White clover (Trifolium repens L.) is at a disadvantage to perennial ryegrass (Lolium perenne L.; PRG) due to its limited cold tolerance and low growth rates at colder temperatures, which can affect subsequent spring herbage dry matter (DM) availability. The effect of PRG ploidy on white clover morphology and growth over winter, and its subsequent...

Monitoring species-specific dry herbage biomass is an important aspect of pasture-based milk production systems. Being aware of the herbage biomass in the field enables farmers to manage surpluses and deficits in herbage supply, as well as using targeted nitrogen fertilization when necessary. Deep learning for computer vision is a powerful tool in...

Extending the grazing season in pasture based systems of dairy production can increase farm profitability; poor weather and soil conditions can reduce the number of grazing days. The study objectives were to (i) examine the effect of restricted access to pasture in the autumn on the milk production, grazing behaviour and DM intake (DMI) of late lac...

The prevalence of “grass-fed” labeled food products on the market has increased in recent years, often commanding a premium price. To date, the majority of methods used for the authentication of grass-fed source products are driven by auditing and inspection of farm records. As such, the ability to verify grass-fed source claims to ensure consumer...

Optimising nutrition for animals requires accurate estimates of feed intake. In research studies determining feed intake in grazing animals can be problematic with many methods requiring individual housing. The n-alkane technique whereby long chain alkanes are used as internal markers for predicting dry matter intake (DMI), facilitates estimation o...

Autumn closing date (CD) in intensive pasture‐based systems influences spring herbage availability. Little is known about the impact of earlier closing of swards in autumn on sward structure. A two‐year experiment was undertaken to investigate the impact of five CD on herbage production, leaf extension rate (LER), leaf senescence rates (LSR), sward...

Correlating volatile compounds with the sensory attributes of whole milk powder (WMP) is fundamental for appreciating the effect of lipid oxidation (LO) on sensory perception. LO compounds can adversely affect the sensory perception of WMP by imparting rancid, metallic, and painty notes. Whole milk powders derived from milk produced by cows maintai...

Altering autumn management affects the herbage mass available in spring. An experiment was established to determine the effect of five autumn closing dates (CDs) on herbage production, herbage quality, leaf, stem and dead proportions and tiller density over winter. In the study 50% of the herbage available in spring was accounted for by autumn CD....

Accurate estimation of herbage mass (HM) is essential for optimising grass utilisation and increasing profit for pasture-based livestock agriculture. The rising plate meter (RPM) is used for predicting HM based on average compressed sward height (CSH). Sampling resolution and distribution are primary parameters in determining spatial heterogeneity...

White clover (WC) offers an alternative source of nitrogen (N) for pasture-based systems. Substituting energy- and carbon-intensive synthetic N fertilizers with N derived from biological fixation by WC has been highlighted as a promising environmental mitigation strategy through the omission of emissions, pollutants, and energy usage during the pro...

Seasonal calving, pasture-based dairy systems are widely practiced in countries with a temperate climate and plentiful rainfall such as Ireland and New Zealand. This approach maximizes milk production from pasture and, consequently, is a low-cost, low-input dairy production system. On the other hand, the majority of global milk supply is derived fr...

The aim of this study was to model the productivity, profitability and the nitrogen (N) utilisation efficiency (NUE) of two spring-calving pasture-based milk production systems differing in milking frequency and intensification levels in New Zealand. For this purpose, physical performance data from a low-intensity production system where cows were...

This review addresses key factors and impediments that govern the efficient transfer of nutrient energy from primary producing grassland to ruminant milk and meat. The review focuses on permanent improved grasslands, defined as “swards maintained at a high production potential by grass-to-grass renewal”, frequently of a 5- to 10-yr longevity. Breed...

Intake and digestibility are key drivers of animal production from grazed forage. The objective of this study was to compare the in vivo digestibility and voluntary dry matter (DM) intake of grass-only and grass-white clover (grass-clover) forage in individually housed sheep. This study was a Latin square design, repeated on three occasions in 2017...

White clover (Trifolium repens L.) is at a disadvantage to perennial ryegrass (Lolium perenne L.; PRG) due to its limited cold tolerance and low growth rates at colder temperatures, which can affect subsequent spring herbage dry matter (DM) availability. The effect of PRG ploidy on white clover morphology and growth over winter, and its subsequent...

In Ireland grazing systems provide the basis of sustainable livestock production, as grazed grass is the cheapest feed source of nutrients for ruminants. The main future objective for these systems is to achieve high grass utilisation, ensure system sustainability and maintain extremely high animal health and welfare. There is no reason why all thr...

The winter diet of dairy cows in Mediterranean climate regions is usually a total mixed ration with a base of conserved summer crops such as corn silage and alfalfa hay. However, there is increased labor and financial cost related to this kind of feeding, which could be reduced if fresh forages were used in place of some of the conserved forage in...

The animal diet is a critical variable affecting the composition and functionality of dairy products. As “Grass-Fed” labeling becomes more prominent on the market, rapid and label-free methods for verification of feeding systems are required. This work proposes the use of Raman spectroscopy to study the effects of 3 different experimental cow feedi...

The performance of ruminant livestock has been shown to benefit from the enhanced nutritive value and herbage yield associated with clover incorporation in the grazing sward. However, little research to date has been conducted investigating the effects of mixed swards containing white clover on the composition of the rumen microbiome. In this study...

The influence of diet on the water-soluble vitamin composition of skim milk powder and whey protein ingredients produced from the milk of cows fed pasture or concentrate-based diets was examined. Fifty-one Holstein-Friesian cows were randomly assigned into three diets (n=17) consisting of outdoor grazing of perennial ryegrass (GRS), perennial ryegr...

In temperate regions of Europe where grass grows for most of the year, grazed pasture is the lowest cost feed for milk production. Grazed pasture can make a contribution to dairy cow feeding systems in other parts of Europe, but is less important. While there are many challenges to maintaining or increasing the proportion of grazed grass in dairy c...

Grazing is inherently close to the nature of herbivores, but no longer applied everywhere in Europe. Therefore, the perception of grassland experts on the occurrence, importance, constraints, solutions and future of grazing of dairy cows was studied. The study builds on results from the European Grassland Federation Working Group Grazing in the per...

The influence of bovine diet on the metabolome of reconstituted skim milk powder (SMP) and protein ingredients produced from the milk of cows fed on pasture or concentrate-based diets was investigated. Cows were randomly assigned to diets consisting of perennial ryegrass only (GRS), perennial ryegrass/white clover sward (CLV), or indoor total mixed...

Increased global demand for dairy produce and the abolition of EU milk quotas have resulted in expansion in dairy production across Europe and particularly in Ireland. Simultaneously, there is increasing pressure to reduce the impact of nitrogen (N) losses to air and groundwater on the environment. In order to develop grassland management strategie...

Milk is a highly nutritious food that contains an array of macro and micro components, scientifically proven to be beneficial to human health. While the composition of milk is influenced by a variety of factors, such as genetics, health, lactation stage etc., the animal’s diet remains a key mechanism by which its nutrition and processing characteri...

Low-heat skim milk powder (LHSMP) was manufactured on 3 separate occasions in mid lactation (ML, July 4-20) and late lactation (LL, September 27 to October 7) from bulk milk of 3 spring-calving dairy herds on different feeding systems: grazing on perennial ryegrass (Lolium perenne L.) pasture (GRO), grazing on perennial ryegrass and white clover (T...

This study examined the effect of dietary factors on compositional and functional properties of whole milk powder (WMP) produced from bovine milk. Raw milk samples were obtained from 3 groups of 18 Holstein Friesian spring-calving cows randomly assigned to diets based on perennial ryegrass (GRS), perennial ryegrass/white clover sward (CLV), and tot...

The untargeted metabolic profiles of ripened Maasdam cheese samples prepared from milk derived from three herd groups, fed: (1) indoors on total mixed ration (TMR), or outdoors on (2) grass only pasture (GRA) or (3) grass and white clover pasture (CLO) were studied using high resolution nuclear magnetic resonance (¹H NMR), high resolution magic ang...

Grass growth models have retrospectively predicted grass growth in Ireland using weather observations. However, to predict future grass growth to aid farm management, weather forecasts are necessary inputs. The Moorepark St. Gilles grass growth model (MoSt GGM) is mechanistic and was developed to predict perennial ryegrass growth on any Irish farm....

Maasdam cheese was manufactured from standardized milk derived from each of three feeding systems: grass (GRA), grass and clover pasture (CLO), and indoor feeding of total mixed ration (TMR). Pasture‐derived cheeses had significantly lower L* (whiteness) and higher b* values (yellowness) compared to TMR‐derived cheeses. Acetate levels were signific...

Context High nitrogen (N)-fertiliser application levels and high stocking rates have been shown to optimise herbage dry-matter (DM) production in grass-only systems. Conversely, swards including white clover (Trifolium repens L.) are commonly suited to production systems at low N-fertiliser application levels (<150 kg N/ha) and low stocking rates (...

This study investigated the effects of pasture versus indoor total mixed ration (TMR) feeding systems on milk and milk solids production, the chemical composition, quality characteristics and sensory properties of raw milk, sweet cream butter and full fat cheddar cheese. The experiment had three treatments. Group 1 was housed indoors and fed a TMR...

The influence of dairy cow feeding regime was investigated using ¹H nuclear magnetic resonance (NMR). Two different NMR analytical systems were deployed: high field ¹H NMR to investigate the influence on milk metabolomics and low field NMR to characterise proton relaxation linked to changes in the state of mozzarella cheese moisture during ripening...

In humid-temperate regions grazed grass is the most economical means of feeding ruminant livestock. Grass growth is often highly variable and therefore difficult to predict. It is influenced by many factors including climatic conditions, soil type and soil nutrients. The Moorepark St. Gilles Grass Growth model (MoSt GG model) is a dynamic model dev...

This study investigated the effects of 3 dairy cow feeding systems on the composition, yield, and biochemical and physical properties of low-moisture part-skim Mozzarella cheese in mid (ML; May-June) and late (LL; October-November) lactation. Sixty spring-calving cows were assigned to 3 herds, each consisting of 20 cows, and balanced on parity, cal...

A 4-year (2010–2013) plot study was undertaken to evaluate the effect of nitrogen (N) fertilizer rate (0, 60, 120, 196 and 240 kg N/ha/year) on seasonal responses and species persistency in frequently and tightly grazed (⩽4 cm) grass-only (GO) and grass white clover swards (GWc). Increasing N application rate increased herbage removed and pre-grazi...

Increasing herbage dry matter (DM) production and utilisation on-farm improves efficiency and sustainability. The objective of this study was to investigate the effect of perennial ryegrass ploidy and white clover inclusion on herbage DM production and grazing efficiency in an intensive animal grazing system with high nitrogen (N) inputs and a high...

Sixty spring-calved cows were allocated to one of three dietary treatments: grazing on perennial ryegrass pasture (GRO), grazing on perennial ryegrass plus white clover pasture (GRC), or housed indoors and offered total mixed ration (TMR). Milk from each treatment was collected on 6 occasions during mid-lactation (17 June - 22 September). The milks...

The potential of grasslands as a carbon (C) sink in Europe is large despite the number of uncertainties related to the effect of grazing systems on C sequestration. The EIP-AGRI Focus Group (FG) ‘Grazing for Carbon’, a temporary group of 20 selected European experts from research and practice, shared knowledge and experience from different discipli...

Increasing herbage dry‐matter (DM) production and utilization on‐farm improves efficiency and sustainability. The objective of this study was to investigate the effect of perennial ryegrass, Lolium perenne L., ploidy and white clover, Trifolium repens L., inclusion on herbage DM production and utilization in an intensive animal grazing system, with...

The purpose of this study was to examine the effects of two pasture feeding systems-perennial ryegrass (GRS) and perennial ryegrass and white clover (CLV)-and an indoor total mixed ration (TMR) system on the (a) rumen microbiome; (b) rumen fluid and milk metabolome; and (c) to assess the potential to distinguish milk from different feeding systems...

Sustainable ruminant production systems depend on the ability of livestock to utilize increased quantities of grazed herbage. The current study aimed to compare the effect of white clover (WC) inclusion and perennial ryegrass (PRG) ploidy on herbage dry matter (DM) production, plant morphology, nutritive value and biological nitrogen (N) fixation (...

White clover (Trifolium repens L.; clover) can offer a superior nutritional feed compared with perennial ryegrass (Lolium perenne L.; PRG) and offers an additional or alternative source (or both) of N for herbage production. The objective of this study was to investigate the effect of including clover into PRG swards receiving 150 (Cl150) or 250 kg...

Le modèle de croissance est un modèle dynamique et mécaniste simulant principalement la croissance d’herbe et l’azote prélevé et lessivé. Le modèle est sensible au climat ainsi qu’à la fertilisation azotée et aux événements de défoliation (fauche ou pâturage). Le modèle a été utilisé pour simuler 10 années climatiques sous 4 niveaux de fertilisatio...

The Irish dairy industry is critically important to the economy and general well-being of a large section of the Irish population. Its quality, sustainability and maintenance are the key for a vibrant rural society in the future. Two important elements for the future of this industry include (a) the quality, marketing and sale of dairy products on...

This study compared the in-vat moisture loss kinetics under fixed cheesemaking conditions during 75 min of stirring of curds prepared from protein-standardised milks produced from indoor cows fed total mixed ration (TMR), or outdoor cows fed grass only (GRA) or grass mixed with clover (CLO). Relative curd moisture as a function of time was fitted t...

The effect of 3 diets (grass, grass/clover, and total mixed ration) on the volatile and sensory properties of bovine milk was assessed over an entire lactation season. Little evidence was found of direct transfer of terpenes into raw milk from the different diets, and it is likely that the monocultures of ryegrass used with and without white clover...

Typical weather in Ireland provides conditions favourable for sustaining grass growth throughout most of the year. This affords grass based farming a significant economic advantage due to the low input costs associated with grass production. To optimize the productivity of grass based systems, farmers must manage the resource over short time scales...

The influence of feeding system and lactation period on the gross composition, macroelements (Ca, P, Mg, and Na), and trace elements (Zn, Fe, Cu, Mo, Mn, Se, and Co) of bovine milk was investigated. The feeding systems included outdoor grazing on perennial ryegrass pasture (GRO), outdoor grazing on perennial ryegrass and white clover pasture (GRC),...

The purpose of this study was to investigate the effects of pasture-based versus indoor total mixed ration (TMR) feeding systems on the chemical composition, quality characteristics, and sensory properties of full fat Cheddar cheeses. Fifty-four multiparous and primiparous Friesian cows were divided into 3 groups (n = 18) for an entire lactation. G...

In temperate grassland, urea has been shown to have lower nitrous oxide emissions compared to ammonium nitrate-based fertilizer and is less expensive. However, nitrogen (N) loss via ammonia volatilization from urea raises questions regarding yield performance and efficiency. This study compares the yield and N offtake of grass fertilized with urea,...

Landscapes typically deemed at risk from leached losses of nitrogen (N) and phosphorus (P) are those with short subsurface hydrologic time lags. Due to the short time it takes nutrients to move from a source to an area of concern, such sites are deemed perfect to test the efficacy of programmes of measures as management changes. However, a small su...

Core Ideas CAN is a widely used form of straight N in Western Europe. Urea+NBPT consistently delivered equal yields and N uptake compared with CAN. CAN had higher N uptake than urea in 2 of 6 site‐years, but yields were not different. NBPT increased the N uptake of urea in 2 of 6 site‐years but had no effect on yield. Urea+DCD had lower yield and N...

The current experiment was undertaken to investigate the effect of including white clover ( Trifolium repens L.; WC) into perennial ryegrass ( Lolium perenne L.; PRG) swards (PRG/WC) receiving 250 kg nitrogen (N) per hectare (ha) per year compared with PRG only swards receiving 250 kg N/ha/year, in an intensive grass-based spring calving dairy prod...

Poster presented at the Ecology and Evolution Ireland Conference 2016 at IT Sligo.

The aim of this study was to investigate the effects of different feeding systems on milk quality and composition. Fifty-four multiparous and primiparous Friesian lactating cows were divided into 3 groups (n = 18) to study the effects of 3 feeding systems over a full lactation. Group 1 was housed indoors and offered a total mixed ration diet (TMR),...

This study evaluated the effects of 3 widely practiced cow feeding systems in the United States, Europe, and Southern Hemisphere regions on the characteristics, quality, and consumer perception of sweet cream butter. Fifty-four multiparous and primiparous Friesian cows were divided into 3 groups (n = 18) for an entire lactation. Group 1 was housed...

In grazed grassland, urine and faeces, returned by grazing animals and added to the nitrogen (N) from fertilizer, augments the N fluxes and also the risk of N losses (leaching, ammonia volatilization). Urine and faeces deposition by the grazing animal result in large applications of N to a small area within the paddock. Many agronomic models do not...

Nitrate (NO3−) leaching and nitrous oxide (N2O) emission from urine patches in grazed pastures are key sources of water and air pollution, respectively. Numerous studies have demonstrated that broadcast application of the nitrification inhibitor dicyandiamide (DCD) can abate such losses of reactive nitrogen (N). This research explored an alternativ...

The productivity of temperate grassland is limited by the response of plants to low temperature, affecting winter persistence and seasonal growth rates. During the winter, the growth of perennial grasses is restricted by a combination of low temperature and the lack of available light, but during early spring low ground temperature is the main limi...

The objective of this study was to evaluate alternative methods of grassland renewal (reseeding) with perennial ryegrass and quantify their effects on subsequent DM yield, tiller density and nitrate leaching. Two experiments were carried out; the first focused on quantifying the influence of Autumn reseeding (August cultivation), and the second, on...

In grass–legume swards, biologically fixed nitrogen (N) from the legume can support the N requirements of the grass, but legume N fixation is suppressed by additional fertilizer N application. This study sought to identify a fertilizer N application rate that maximizes herbage and N yields, N fixation and apparent N transfer from white clover to co...

In agricultural production systems, nitrogen (N) losses to the environment can occur through nitrous oxide (N 2 O) emissions and nitrate (NO 3 − ) leaching. The objectives of the present study were to evaluate: (1) if urine excreted by non-lactating dairy cows pulse-dosed with dicyandiamide (DCD) and applied to lysimeters reduced N 2 O-N emissions...

In temperate and oceanic regions, grazed grass is the lowest cost feed available for milk production. Inother regions, grazed grass is less important but can contribute to the diet of livestock. Within high outputsystems the interaction between the animal and sward is challenging for a host of reasons, includingintake and milk production potential,...

Economically viable and productive farming systems are required to meet the growing worldwide need for agricultural produce while at the same time reducing environmental impact. Within grazing systems of animal production, increasing concern exists as to the effect of intensive farming on potential N losses to ground and surface waters, which deman...

In temperate and oceanic regions, grazed grass is the lowest cost feed available for milk production. In other regions, grazed grass is less important but can contribute to the diet of livestock. Within high output systems the interaction between the animal and sward is challenging for a host of reasons, including intake and milk production potenti...

Ireland has conditions that favour grass growth throughout most of the year, resulting in a competitive advantage in providing ruminant production systems with a cheap feed source. Grass growth is highly seasonal with little growth over the winter period due to low temperatures and low levels of sunshine/solar radiation. Peak grass growth occurs in...