• How much grassland biomass is available in Ireland in excess of livestock requirements?

      McEniry, Joseph; Crosson, Paul; Finneran, Eoghan; McGee, Mark; Keady, Tim; O'Kiely, Padraig; Department of Agriculture, Food and the Marine; RSF 07 557 (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Grassland is a dominant biomass resource in Ireland and underpins most animal production systems. However, other commercial uses for grassland biomass exist, including, for example, the production of biogas through anaerobic digestion for the generation of heat, electricity and transport fuel. The objective of this study was to estimate the annual grassland resource available in Ireland in excess of livestock requirements under six contrasting scenarios. Under current grassland management and production practices there is an estimated average annual grassland resource of ca. 1.7 million tonnes of dry matter (DM) available in excess of livestock requirements. Only a small proportion of this resource (0.39 million tonnes of DM per annum) would be available if the targets set out in ‘Food Harvest 2020’ were achieved. However, increasing nitrogen (N) fertiliser input (to the limit permitted by the E.U. Nitrates Directive) combined with increasing the grazed grass utilisation rate of cattle (from 0.60 to 0.80 kg DM ingested by livestock per kg DM grown) has the potential to significantly increase this average resource to 12.2 million t DM/annum, even when allowing for achievement of ‘Food Harvest 2020’ targets. Under these scenarios, alternative uses for grassland biomass such as anaerobic digestion and green biorefining would not compete with traditional dairy, beef and lamb production systems, but could provide an alternative enterprise and income to farmers.
    • Impact of agronomic practices of an intensive dairy farm on nitrogen concentrations in a karst aquifer in Ireland

      Huebsch, Manuela; Horan, Brendan; Blum, P.; Richards, Karl G.; Grant, Jim; Fenton, Owen; Teagasc Walsh Fellowship Programme (Elsevier, 24/09/2013)
      Exploring the relationship between agricultural nitrogen loading on a dairy farm and groundwater reactive nitrogen concentration such as nitrate is particularly challenging in areas underlain by thin soils and karstified limestone aquifers. The objective of this study is to relate changes in detailed agronomic N-loading, local weather conditions, hydrogeological and geological site characteristics with groundwater N occurrence over an 11-year period on an intensive dairy farm with free draining soils and a vulnerable limestone aquifer. In addition, the concept of vertical time lag from source to receptor is considered. Statistical analysis used regression with automatic variable selection. Four scenarios were proposed to describe the relationships between paddock and groundwater wells using topographic and hydrogeological assumptions. Monitored nitrate concentrations in the studied limestone aquifer showed a general decrease in the observed time period (2002–2011). Statistical results showed that a combination of improved agronomic practices and site specific characteristics such as thicknesses of the soil and unsaturated zone together with hydrogeological connections of wells and local weather conditions such as rainfall, sunshine and soil moisture deficit were important explanatory variables for nitrate concentrations. Statistical results suggested that the following agronomic changes improved groundwater quality over the 11-year period: reductions in inorganic fertiliser usage, improvements in timing of slurry application, the movement of a dairy soiled water irrigator to less karstified areas of the farm and the usage of minimum cultivation reseeding on the farm. In many cases the explanatory variables of farm management practices tended to become more important after a 1- or 2-year time lag. Results indicated that the present approach can be used to elucidate the effect of farm management changes to groundwater quality and therefore the assessment of present and future legislation implementations.
    • Incorporating white clover (Trifolium repens L.) into perennial ryegrass (Lolium perenne L.) swards receiving varying levels of nitrogen fertilizer: Effects on milk and herbage production

      Egan, Michael; Galvin, Norann; Hennessy, Deirdre; Teagasc Walsh Fellowship Programme; Irish Dairy Levy (Elsevier, 2018-02-04)
      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 of N/ha (Cl250) compared with a PRG-only sward receiving 250 kg of N/ha (Gr250) on herbage production, milk production, and herbage dry matter intake (DMI) in an intensive grass-based spring calving milk production system over 2 full lactations. A farm systems experiment was established in February 2013, and conducted over 2 grazing seasons [2013 (yr 1) and 2014 (yr 2)]. In February 2013 (yr 1), 42 Holstein-Friesian spring-calving dairy cows, and in February 2014 (yr 2), 57 Holstein-Friesian spring-calving dairy cows were allocated to graze the Cl150, Cl250, and Gr250 swards (n = 14 in yr 1 and n = 19 in yr 2) from February to November, at a stocking rate of 2.74 cows/ha. Herbage DMI was estimated twice in yr 1 (May and September) and 3 times in yr 2 (May, July, and September). Treatment did not have a significant effect on annual herbage production. Sward clover content was greater on the Cl150 treatment than the Cl250 treatment. The cows grazing both clover treatments (Cl250 and Cl150) produced more milk than the cows grazing Gr250 from June until the end of the grazing season. A significant treatment by measurement period interaction was observed on total DMI. In May, the cows on the Cl250 treatment had the greatest DMI. In July, the cows on the clover treatments had greater DMI than those on the Gr250 treatment, whereas in September, the cows on the Cl150 treatment had the lowest DMI. In conclusion, including clover in a PRG sward grazed by spring-calving dairy cows can result in increased animal performance, particularly in the second half of lactation. Reducing N fertilizer application to 150 kg of N/ha on grass-clover swards did not reduce herbage production compared with grass-only swards receiving 250 kg of N/ha. White clover can play an integral role in intensive grazing systems in terms of animal performance and herbage production.
    • Influence of testing procedure on evaluation of white clover (Trifolium repens L.)

      Gilliland, T. J.; McGilloway, D.; Conaghan, Patrick (Teagasc, Oak Park, Carlow, Ireland, 2009)
      This study examined data sets derived from the white clover cultivar evaluation programmes of AFBI (N. Ireland), and DAFF (Republic of Ireland) to determine whether elite performing genotypes are identifiable, independent of test procedure and leaf size factors. Genetic variation in yield and persistency, independent of the leaf size continuum effect, was observed. Identification of elite cultivars by breeders or testers therefore required readjustment of assessment standards to account for the mostly curvilinear relationships between performance and leaf size. The different testing procedures, involving cutting or grazing at different heights, frequencies and nitrogen rates changed the relative performances between the cultivars, making it difficult to predict performance potential beyond specific test conditions. The underlying causes for these changes in rankings was considered, including sensitivity to season and location, the antagonistic affects of defoliation pressure and companion grass competition, the independence of different seasonal profiles and the probable role of other morphological characteristics. In is concluded that testing authorities must calculate the management by leaf size relationships to adjust pass/fail standards if elite performing cultivars are to be correctly indentified.
    • Infrared thermography as a tool to detect hoof lesions in sheep

      Byrne, Daire T; Berry, Donagh; Esmonde, Harold; McGovern, Fiona; Creighton, Philip; McHugh, Noirin; Department of Agriculture, Food, and the Marine; RSF 11/S/133 (Oxford University Press (OUP), 2018-12-08)
      Lameness has a major negative impact on sheep production. The objective of this study was to 1) quantify the repeatability of sheep hoof temperatures estimated using infrared thermography (IRT); 2) determine the relationship between ambient temperature, sheep hoof temperature, and sheep hoof health status; and 3) validate the use of IRT to detect infection in sheep hooves. Three experiments (a repeatability, exploratory, and validation experiment) were conducted over 10 distinct nonconsecutive days. In the repeatability experiment, 30 replicate thermal images were captured from each of the front and back hooves of nine ewes on a single day. In the exploratory experiment, hoof lesion scores, locomotion scores, and hoof thermal images were recorded every day from the same cohort of 18 healthy ewes in addition to a group of lame ewes, which ranged from one to nine ewes on each day. Hoof lesion and locomotion scores were blindly recorded by three independent operators. In the validation experiment, all of the same procedures from the exploratory experiment were applied to a new cohort of 40 ewes across 2 d. The maximum and average temperature of each hoof was extracted from the thermal images. Repeatability of IRT measurements was assessed by partitioning the variance because of ewe and error using mixed models. The relationship between ambient temperature, hoof temperature, and hoof health status was quantified using mixed models. The percentage of hooves correctly classified as healthy (i.e., specificity) and infected (i.e., sensitivity) was calculated for a range of temperature thresholds. Results showed that a small-to-moderate proportion of the IRT-estimated temperature variability in a given hoof was due to error (1.6% to 20.7%). A large temperature difference (8.5 °C) between healthy and infected hooves was also detected. The maximum temperature of infected hooves was unaffected by ambient temperature (P > 0.05), whereas the temperature of healthy hooves was associated with ambient temperature. The best sensitivity (92%) and specificity (91%) results in the exploratory experiment were observed when infected hooves were defined as having a maximum hoof temperature ≥9 °C above the average of the five coldest hooves in the flock on that day. When the same threshold was applied to the validation dataset, a sensitivity of 77% and specificity of 78% was achieved, indicating that IRT could have the potential to detect infection in sheep hooves.
    • Intake, growth and feed conversion efficiency of finishing beef cattle offered diets based on triticale, maize or grass silages, or ad libitum concentrates

      O'Kiely, Padraig (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      The intake, growth and feed conversion efficiency of finishing cattle offered whole-crop triticale silage, harvested at different stubble heights, or maize silage, supplemented with different amounts and forms of crude protein, were compared with those of cattle offered grass silage or concentrate ad libitum. Ninety-eight continental crossbred steers (mean (s.d.) initial live weight 509 (38.6) kg) were allocated among 7 treatments in a randomized complete-block design: triticale silage from a crop harvested to a 14 (TS-L) or 35 (TS-H) cm high stubble, maize silage supplemented with a low (MS-LS) or high (MS-HS) protein concentrate, or with approximately half of the supplementary crude protein replaced by urea (MS-SU), grass silage (GS) or concentrate offered ad libitum (ALC). Each silage was offered ad libitum for 134 days, supplemented with 3 kg concentrate per head daily. Carcass gain did not differ (P>0.05) between animals on treatments TS-L and TS-H, but the carcass gain associated with TS-L was lower (P<0.05) than with GS or MS-HS, and with TS-H compared with MS-HS. Carcass gain was lower (P<0.05) for steers on GS compared to MS-HS, there were no differences (P>0.05) among the values for MS-LS, MS-HS and MS-SU; the carcass gain associated with ALC was the highest (P<0.001). The feed efficiency for carcass gain for the animals on TS-L, TS-H, GS, MS-LS, MS-HS, MS-SU and ALC was 44.1, 48.2, 60.8, 59.3, 68.3, 59.8 and 90.1 (s.e. 4.26) kg/t total DM intake, respectively (P<0.001). It is concluded that the ranking on nutritive value was TS<GS<MS<ALC. Elevating the cutting height of triticale conferred little benefit. Half the soybean meal in the barley-based supplement to maize silage could be replaced by barley plus urea without a negative effect on animal performance.
    • Integration of high and low field 1H NMR to analyse the effects of bovine dietary regime on milk metabolomics and protein-bound moisture characterisation of the resulting mozzarella cheeses during ripening

      Boiani, Mattia; Sundekilde, Ulrik; Bateman, Lorraine M.; McCarthy, Daniel G.; Maguire, Anita R.; Gulati, Arunima; Guinee, Timothy P.; Fenelon, Mark; Hennessy, Deirdre; Fitzgerald, Richard J.; et al. (Elsevier, 2018-10-11)
      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. The metabolomics results showed that grass-based feeding increased the concentration of a biological marker that signifies near-organic milk production conditions. On the other hand, the investigation of cheese moisture distribution showed that grass-based diets reached final moisture partitioning in a shorter time, which implied the formation of a more compact protein structure in the cheese matrix. These results indicate that pasture-based dairying may be differentiated in terms of the provenance of milk produced along with the accrual of additional benefits during ripening of the resulting mozzarella cheeses.
    • Investigating the role of stocking rate and prolificacy potential on profitability of grass based sheep production systems

      Bohan, A.; Creighton, Philip; Boland, T.M.; Shalloo, Laurence; Earle, Elizabeth; McHugh, Noirin; Department of Agriculture, Food and the Marine; 15/S/696 (Elsevier BV, 2018-02-21)
      The objective of this study was to simulate and compare the profitability of a grass based sheep production system under three stocking rates and two prolificacy rates. Analysis was conducted using the Teagasc Lamb Production Model (TLPM), a stochastic budgetary simulation model of a sheep farm. Experimental data from the Teagasc Athenry Research Demonstration Flock was used to parameterise the model at three stocking rates (10, 12 and 14 ewes/ha) and two prolificacy potentials (1.5 and 1.8 lambs weaned per ewe joined to the ram). The TLPM assessed the performance of the key factors affecting profitability and was also used to evaluate the spread in profitability associated with some stochastic variables included in the analysis. The number of lambs weaned per hectare increased with stocking rate and prolificacy potential from 16 lambs/ha to 27 lambs/ha resulting in carcass weight produced per hectare ranging from 272 kg/ha to 474 kg/ha. Increasing stocking rates resulted in lower individual lamb performance from grass and milk, thereby increasing the proportion of lambs which required concentrate for finishing, which resulted in higher input costs on a per animal basis. As the number of lambs weaned per hectare increased, net profit increased from €361/ha to €802/ha. Across all stocking rates, increasing weaning rate from 1.5 to 1.8 lambs weaned per ewe joined increased net profit, on average, by €336/ha. Increasing stocking rate, at 1.5 lambs weaned per ewe joined, increased net profit on average by €15/ha while increasing stocking rate, at 1.8 lambs weaned per ewe joined increased net profit on average by €87/ha. Risk analysis showed that across all stocking rates the high prolificacy scenarios achieved greater profits across the variation in input variables. Results from this study indicate that lambs weaned per hectare linked with grass growth and utilisations are the key drivers of profitability on Irish grass based sheep production systems.
    • Manipulating the ensilage of wilted, unchopped grass through the use of additive treatments

      McEniry, Joseph; O'Kiely, Padraig; Clipson, Nicholas J.W.; Forristal, P.D.; Doyle, Evelyn M.; Teagasc Walsh Fellowship Programme (Teagasc, Oak Park, Carlow, Ireland, 2007)
      Baled silage composition frequently differs from that of comparable conventional precision-chop silage. The lower final concentration of fermentation products in baled silage makes it more conducive to the activities of undesirable microorganisms. Silage additives can be used to encourage beneficial microbial activity and/or inhibit detrimental microbial activity. The experiment was organised in a 2 (chop treatments) × 6 (additive treatments) × 2 (stages of ensilage) factorial arrangement of treatments (n = 3 silos/treatment) to suggest additive treatments for use in baled silage production that would help create conditions more inhibitory to the activities of undesirable microorganisms and realise an outcome comparable to precision-chop silage. Chopping the herbage prior to ensiling, in the absence of an additive treatment, improved the silage fermentation. In the unchopped herbage, where the fermentation was poorer, the lactic acid bacterial inoculant resulted in an immediate increase (P < 0.001) in lactic acid concentration and a faster decline (P < 0.001) in pH with a subsequent reduction in butyric acid (P < 0.001) and ammonia-N (P < 0.01) concentrations. When sucrose was added in addition to the lactic acid bacterial inoculant, the combined treatment had a more pronounced effect on pH, butyric acid and ammonia-N values at the end of ensilage. The formic acid based additive and the antimicrobial mixture restricted the activities of undesirable microorganisms resulting in reduced concentrations of butyric acid (P < 0.001) and ammonia-N (P < 0.01). These additives offer a potential to create conditions in baled silage more inhibitory to the activities of undesirable microorganisms.
    • Manipulation of grass supply to meet feed demand

      French, Padraig; Hennessy, Deirdre; O’Donovan, Michael; Laidlaw, S. (Teagasc, 2006-01-01)
      Grazed grass is generally the cheapest form of feed available for beef and milk production in Ireland. Grass growth is variable during the year with a peak in May/June and a secondary peak in August. There is little net growth from December to February. Grass growth is also variable across the country with higher grass growth in the south and south-west (14 to 15 t DM/ha/year) compared with approximately 11 t DM/ha/year in the north-east (Brereton, 1995). There is poor synchrony between grass supply and feed demand on beef and dairy farms. The feed demand curve for a calf to two year old beef system shows feed demand decreasing as grass supply increases, and grass supply decreasing as feed demand increases. Similarly, the feed demand curve of a spring calving dairy herd shows poor synchrony with grass supply, with a surplus of grass from about mid-April to mid-August, and a deficit for the rest of the year. Traditionally surplus grass produced during May and June is conserved as silage or hay and fed back to cattle and dairy cows during the deficit times of the year.
    • Markers associated with heading and aftermath heading in perennial ryegrass full-sib families

      Arojju, Sai Krishna; Barth, Susanne; Milbourne, Dan; Conaghan, Patrick; Velmurugan, Janaki; Hodkinson, Trevor R; Byrne, Stephen L.; Department of Agriculture, Food and the Marine, Ireland; Teagasc Walsh Fellowship Programme; EU Marie-Sklodowska-Curie Fellowship; et al. (Biomed Central, 16/07/2016)
      Background Heading and aftermath heading are important traits in perennial ryegrass because they impact forage quality. So far, genome-wide association analyses in this major forage species have only identified a small number of genetic variants associated with heading date that overall explained little of the variation. Some possible reasons include rare alleles with large phenotypic affects, allelic heterogeneity, or insufficient marker density. We established a genome-wide association panel with multiple genotypes from multiple full-sib families. This ensured alleles were present at the frequency needed to have sufficient statistical power to identify associations. We genotyped the panel via partial genome sequencing and performed genome-wide association analyses with multi-year phenotype data collected for heading date, and aftermath heading. Results Genome wide association using a mixed linear model failed to identify any variants significantly associated with heading date or aftermath heading. Our failure to identify associations for these traits is likely due to the extremely low linkage disequilibrium we observed in this population. However, using single marker analysis within each full-sib family we could identify markers and genomic regions associated with heading and aftermath heading. Using the ryegrass genome we identified putative orthologs of key heading genes, some of which were located in regions of marker-trait associations. Conclusion Given the very low levels of LD, genome wide association studies in perennial ryegrass populations are going to require very high SNP densities. Single marker analysis within full-sibs enabled us to identify significant marker-trait associations. One of these markers anchored proximal to a putative ortholog of TFL1, homologues of which have been shown to play a key role in continuous heading of some members of the rose family, Rosaceae.
    • Meta-analysis of the effect of white clover inclusion in perennial ryegrass swards on milk production

      Dineen, Michael; Delaby, Luc; Gilliland, T.; McCarthy, Brian; Teagasc Walsh Fellowship Programme; Irish Dairy Levy (Elsevier, 2017-11-23)
      There is increased demand for dairy products worldwide, which is coupled with the realization that consumers want dairy products that are produced in a sustainable and environmentally benign manner. Forage legumes, and white clover (Trifolium repens L.; WC) in particular, have the potential to positively influence the sustainability of pasture-based ruminant production systems. Therefore, there is increased interest in the use of forage legumes because they offer opportunities for sustainable pasture-based production systems. A meta-analysis was undertaken to quantify the milk production response associated with the introduction of WC into perennial ryegrass swards and to investigate the optimal WC content of dairy pastures to increase milk production. Two separate databases were created. In the grass-WC database, papers were selected if they compared milk production of lactating dairy cows grazing perennial ryegrass-WC (GC) swards with that of cows grazing perennial ryegrass-only swards (GO). In the WC-only database, papers were selected if they contained milk production from lactating dairy cows grazing on GC swards with varying levels of WC content. Data from both databases were analyzed using mixed models (PROC MIXED) in SAS (SAS Institute, Cary, NC). Within the grass-WC database, where mean sward WC content was 31.6%, mean daily milk and milk solids yield per cow were increased by 1.4 and 0.12 kg, respectively, whereas milk and milk solids yield per hectare were unaffected when cows grazed GC compared with GO swards. Stocking rate and nitrogen fertilizer application were reduced by 0.25 cows/ha and 81 kg/ha, respectively, on GC swards compared with GO swards. These results highlight the potential of GC production systems to achieve similar levels of production to GO systems but with reduced fertilizer nitrogen inputs, which is beneficial from both an economic and environmental point of view. In the context of increased demand for dairy products, there may be potential to increase the productivity of GC systems by increasing fertilizer nitrogen use to increase stocking rate and carrying capacity while also retaining the benefit of WC inclusion on milk production per cow.
    • The microbiological and chemical composition of baled and precision-chop silages on a sample of farms in County Meath

      McEniry, Joseph; O'Kiely, Padraig; Clipson, Nicholas J.W.; Forristal, P.D.; Doyle, Evelyn M.; Teagasc Walsh Fellowship Programme; (Teagasc, Oak Park, Carlow, Ireland, 2006)
      Baled and precision-chop silages were examined on a sample of farms in the Irish midlands to determine microbiological and chemical composition at feedout. Silage making practices and chemical composition were similar to those in national surveys. Wilting was an integral part of baled silage production and was reflected in a more restricted fermentation (higher pH and water-soluble carbohydrates, with lower fermentation acids and buffering capacity) compared to precision-chop silage. Yeast numbers were higher in baled silage, suggesting a more aerobic environment within the bale. Although the fermentation appeared similar in the outer and inner horizons of baled silage, yeast, lactic acid bacteria and Enterobacteria numbers were higher in the outer horizon suggesting less exacting anaerobiosis adjacent to the surface of the bale.
    • Milk production of Holstein-Friesian cows of divergent Economic Breeding Index evaluated under seasonal pasture-based management

      O'Sullivan, Margaret; Horan, Brendan; Pierce, Karina M.; McParland, Sinead; O'Sullivan, Kathleen; Buckley, Frank (Elsevier, 2019-01-03)
      The objective of this study was to validate the effect of genetic improvement using the Irish genetic merit index, the Economic Breeding Index (EBI), on total lactation performance and lactation profiles for milk yield, milk solids yield (fat plus protein; kg), and milk fat, protein, and lactose content within 3 pasture-based feeding treatments (FT) and to investigate whether an interaction exists between genetic group (GG) of Holstein-Friesian and pasture-based FT. The 2 GG were (1) extremely high EBI representative of the top 5% nationally (referred to as the elite group) and (2) representative of the national average EBI (referred to as the NA group). Cows from each GG were randomly allocated each year to 1 of 3 pasture-based FT: control, lower grass allowance, and high concentrate. The effects of GG, FT, year, parity, and the interaction between GG and FT adjusted for calving day of year on milk and milk solids (fat plus protein; kg) production across lactation were studied using mixed models. Cow was nested within GG to account for repeated cow records across years. The overall and stage of lactation-specific responses to concentrate supplementation (high concentrate vs. control) and reduced pasture allowance (lower grass allowance vs. control) were tested. Profiles of daily milk yield, milk solids yield, and milk fat, protein, and lactose content for each week of lactation for the elite and NA groups within each FT and for each parity group within the elite and NA groups were generated. Phenotypic performance was regressed against individual cow genetic potential based on predicted transmitting ability. The NA cows produced the highest milk yield. Milk fat and protein content was higher for the elite group and consequently yield of solids-corrected milk was similar, whereas yield of milk solids tended to be higher for the elite group compared with the NA group. Milk lactose content did not differ between GG. Responses to concentrate supplementation or reduced pasture allowance did not differ between GG. Milk production profiles illustrated that elite cows maintained higher production but with lower persistency than NA cows. Regression of phenotypic performance against predicted transmitting ability illustrated that performance was broadly in line with expectation. The results illustrate that the superiority of high-EBI cattle is consistent across diverse pasture-based FT. The results also highlight the success of the EBI to deliver production performance in line with the national breeding objective: lower milk volume with higher fat and protein content.
    • Milk production per cow and per hectare of spring-calving dairy cows grazing swards differing in Lolium perenne L. ploidy and Trifolium repens L. composition

      McClearn, Bríd; Gilliland, Trevor J.; Delaby, Luc; Guy, Clare; Dineen, Michael; Coughlan, Fergal; McCarthy, Brian; Teagasc Walsh Fellowship Programme; Dairy Research Ireland (Elsevier, 2019-07-10)
      Grazed grass is the cheapest feed available for dairy cows in temperate regions; thus, to maximize profits, dairy farmers must optimize the use of this high-quality feed. Previous research has defined the benefits of including white clover (Trifolium repens L.) in grass swards for milk production, usually at reduced nitrogen usage and stocking rate. The aim of this study was to quantify the responses in milk production of dairy cows grazing tetraploid or diploid perennial ryegrass (Lolium perenne L.; PRG) sown with and without white clover but without reducing stocking rate or nitrogen usage. We compared 4 grazing treatments in this study: tetraploid PRG-only swards, diploid PRG-only swards, tetraploid with white clover swards, and diploid with white clover swards. Thirty cows were assigned to each treatment, and swards were rotationally grazed at a farm-level stocking rate of 2.75 cows/ha and a nitrogen fertilizer rate of 250 kg/ha annually. Sward white clover content was 23.6 and 22.6% for tetraploid with white clover swards and diploid with white clover swards, respectively. Milk production did not differ between the 2 ploidies during this 4-yr study, but cows grazing the PRG-white clover treatments had significantly greater milk yields (+596 kg/cow per year) and milk solid yields (+48 kg/cow per year) compared with cows grazing the PRG-only treatments. The PRG-white clover swards also produced 1,205 kg of DM/ha per year more herbage, which was available for conserving and buffer feeding in spring when these swards were less productive than PRG-only swards. Although white clover is generally combined with reduced nitrogen fertilizer use, this study provides evidence that including white clover in either tetraploid or diploid PRG swards, combined with high levels of nitrogen fertilizer, can effectively increase milk production per cow and per hectare.
    • Milk production per cow and per hectare of spring-calving dairy cows grazing swards differing in Lolium perenne L. ploidy and Trifolium repens L. composition

      McClearn, B.; Gilliland, T.J.; Delaby, L.; Guy, C.; Dineen, M.; Coughlan, F.; McCarthy, B.; Dairy Research Ireland; Teagasc Walsh Fellowship Programme (American Dairy Science Association, 2019-09)
      Grazed grass is the cheapest feed available for dairy cows in temperate regions; thus, to maximize profits, dairy farmers must optimize the use of this high-quality feed. Previous research has defined the benefits of including white clover (Trifolium repens L.) in grass swards for milk production, usually at reduced nitrogen usage and stocking rate. The aim of this study was to quantify the responses in milk production of dairy cows grazing tetraploid or diploid perennial ryegrass (Lolium perenne L.; PRG) sown with and without white clover but without reducing stocking rate or nitrogen usage. We compared 4 grazing treatments in this study: tetraploid PRG-only swards, diploid PRG-only swards, tetraploid with white clover swards, and diploid with white clover swards. Thirty cows were assigned to each treatment, and swards were rotationally grazed at a farm-level stocking rate of 2.75 cows/ha and a nitrogen fertilizer rate of 250 kg/ha annually. Sward white clover content was 23.6 and 22.6% for tetraploid with white clover swards and diploid with white clover swards, respectively. Milk production did not differ between the 2 ploidies during this 4-yr study, but cows grazing the PRG-white clover treatments had significantly greater milk yields (+596 kg/cow per year) and milk solid yields (+48 kg/cow per year) compared with cows grazing the PRG-only treatments. The PRG-white clover swards also produced 1,205 kg of DM/ha per year more herbage, which was available for conserving and buffer feeding in spring when these swards were less productive than PRG-only swards. Although white clover is generally combined with reduced nitrogen fertilizer use, this study provides evidence that including white clover in either tetraploid or diploid PRG swards, combined with high levels of nitrogen fertilizer, can effectively increase milk production per cow and per hectare
    • Mobilisation or dilution? Nitrate response of karst springs to high rainfall events

      Huebsch, Manuela; Fenton, Owen; Horan, Brendan; Hennessy, Deirdre; Richards, Karl G.; Jordan, Philip; Goldscheider, N.; Butscher, C.; Blum, P.; Teagasc Walsh Fellowship Programme (European Geosciences Union, 05/11/2014)
      Nitrate (NO3−) contamination of groundwater associated with agronomic activity is of major concern in many countries. Where agriculture, thin free draining soils and karst aquifers coincide, groundwater is highly vulnerable to nitrate contamination. As residence times and denitrification potential in such systems are typically low, nitrate can discharge to surface waters unabated. However, such systems also react quickest to agricultural management changes that aim to improve water quality. In response to storm events, nitrate concentrations can alter significantly, i.e. rapidly decreasing or increasing concentrations. The current study examines the response of a specific karst spring situated on a grassland farm in South Ireland to rainfall events utilising high-resolution nitrate and discharge data together with on-farm borehole groundwater fluctuation data. Specifically, the objectives of the study are to formulate a scientific hypothesis of possible scenarios relating to nitrate responses during storm events, and to verify this hypothesis using additional case studies from the literature. This elucidates the controlling key factors that lead to mobilisation and/or dilution of nitrate concentrations during storm events. These were land use, hydrological condition and karstification, which in combination can lead to differential responses of mobilised and/or diluted nitrate concentrations. Furthermore, the results indicate that nitrate response in karst is strongly dependent on nutrient source, whether mobilisation and/or dilution occur and on the pathway taken. This will have consequences for the delivery of nitrate to a surface water receptor. The current study improves our understanding of nitrate responses in karst systems and therefore can guide environmental modellers, policy makers and drinking water managers with respect to the regulations of the European Union (EU) Water Framework Directive (WFD). In future, more research should focus on the high-resolution monitoring of karst aquifers to capture the high variability of hydrochemical processes, which occur at time intervals of hours to days.
    • Multi-year evaluation of stocking rate and animal genotype on milk production per hectare within intensive pasture-based production systems

      Coffey, E. L.; Delaby, Luc; Fleming, C.; Pierce, K.M.; Horan, Brendan; Dairy Research Levy (Elsevier, 2017-12-14)
      The objective of this experiment was to evaluate the effect of stocking rate (SR) and animal genotype (BR) on milk production, body weight (BW), and body condition score (BCS) within intensive pasture-based systems. A total of 533 lactation records, from 246 elite genetic merit dairy cows were available for analysis; 68 Holstein-Friesian (HF) and 71 Jersey × Holstein-Friesian (JxHF) crossbred cows in each of 4 consecutive years (2013–2016, inclusive). Cows from each BR were randomly allocated to 1 of 3 whole-farm comparative SR treatments, low (LSR; 1,200 kg of BW/ha), medium (MSR; 1,400 kg of BW/ha), and high (HSR; 1,600 kg of BW/ha), and remained in the same SR treatments for the duration of the experiment. The effects of SR, BR, and their interaction on milk production/cow and per hectare, BW, BCS, and grazing characteristics were analyzed. Total pasture utilization per hectare consumed in the form of grazed pasture increased linearly as SR increased: least in LSR (10,237 kg of dry matter/ha), intermediate in MSR (11,016 kg of dry matter/ha), and greatest in HSR (11,809 kg of dry matter/ha). Milk and milk solids (MS) yield per hectare was greatest for HSR (15,942 and 1,354 kg, respectively), intermediate for MSR (14,191 and 1,220 kg, respectively), and least for LSR (13,186 and 1,139 kg, respectively) with similar trends evident for fat, protein, and lactose yield/ha. At higher SR (MSR and HSR), MS yield per kg of BW per ha was reduced (0.85 and 0.82 kg of MS/kg of BW, respectively) compared with LSR (0.93 kg of MS/kg of BW/ha). Holstein-Friesian cows achieved fewer grazing days per hectare (−37 d), and produced more milk (+561 kg/ha) but less fat plus protein (−57 kg/ha) compared with JxHF cows; the JxHF cows were lighter. At similar BW per hectare, JxHF cows produced more fat plus protein/ha during the grazing season at low (1,164 vs. 1,113 kg), medium (1,254 vs. 1,185 kg), and high (1,327 vs. 1,380 kg) SR. In addition, JxHF cows produced more fat plus protein per kg of BW/ha (0.90 kg) compared with HF cows (0.84 kg). The results highlight the superior productive efficiency of high genetic potential crossbred dairy cows within intensive pasture-based production systems.
    • A note on the chemical composition and in vitro digestibility of contrasting stover components of maize grown in climatically marginal conditions and harvested at differing maturities.

      Lynch, J.P.; O'Kiely, Padraig; Doyle, Evelyn M.; Department of Agriculture, Food and the Marine; RSF 07 501 (Teagasc (Agriculture and Food Development Authority), Ireland, 2014)
      This study evaluated the nutritive value of three contrasting components of maize stover (leaf, upper stem, lower stem) at three harvest dates. The leaf component had a greater in vitro dry matter digestibility (DMD) and a lower NDF concentration, compared to the stem components. Delaying harvest reduced the in vitro DMD of the stem components to a greater extent than leaf, reflecting lower increases in the NDF and lignin concentrations in leaf tissue. The stem components of maize stover had a lower nutritive value than the leaf component, and had a larger decrease in digestibility with delayed harvest.
    • A note on the comparison of three near infrared reflectance spectroscopy calibration strategies for assessing herbage quality of ryegrass

      Burns, G. A.; O'Kiely, Padraig; Grogan, D.; Gilliland, T. J.; Department of Agriculture, Food and the Marine; RSF 07 526 (Teagasc (Agriculture and Food Development Authority), Ireland, 2014)
      Perennial ryegrass (n = 1,836), Italian ryegrass (n = 137) and hybrid ryegrass (n = 103) herbage was taken from harvested plots from the Irish national variety evaluation scheme and analysed for in vitro dry matter digestibility, water soluble carbohydrate concentration, crude protein concentration and buffering capacity. Spectral data were obtained using near infrared reflectance spectroscopy and three calibration strategies (global, species-specific or local) were utilised to relate the reference values to the spectral data. The local strategy generally provided the poorest estimation of herbage composition, with global and species-specific calibration strategies producing similarly accurate estimates of each quality trait. The higher accuracy and easier maintenance of the global strategy make it the recommended calibration method for analysing quality of ryegrass.