• Gastrointestinal tract size, total-tract digestibility, and rumen microflora in different dairy cow genotypes

      Beecher, Marion; Buckley, Frank; Waters, Sinead M.; Boland, T. M.; Enriquez-Hidalgo, D.; Deighton, M. H.; O'Donovan, Michael; Lewis, Eva (Elsevier Inc and American Dairy Science Association, 2014-04-03)
      The superior milk production efficiency of Jersey (JE) and Jersey × Holstein-Friesian (JE × HF) cows compared with Holstein-Friesian (HF) has been widely published. The biological differences among dairy cow genotypes, which could contribute to the milk production efficiency differences, have not been as widely studied however. A series of component studies were conducted using cows sourced from a longer-term genotype comparison study (JE, JE × HF, and HF). The objectives were to (1) determine if differences exist among genotypes regarding gastrointestinal tract (GIT) weight, (2) assess and quantify whether the genotypes tested differ in their ability to digest perennial ryegrass, and (3) examine the relative abundance of specific rumen microbial populations potentially relating to feed digestibility. Over 3 yr, the GIT weight was obtained from 33 HF, 35 JE, and 27 JE × HF nonlactating cows postslaughter. During the dry period the cows were offered a perennial ryegrass silage diet at maintenance level. The unadjusted GIT weight was heavier for the HF than for JE and JE × HF. When expressed as a proportion of body weight (BW), JE and JE × HF had a heavier GIT weight than HF. In vivo digestibility was evaluated on 16 each of JE, JE × HF, and HF lactating dairy cows. Cows were individually stalled, allowing for the total collection of feces and were offered freshly cut grass twice daily. During this time, daily milk yield, BW, and dry matter intake (DMI) were greater for HF and JE × HF than for JE; milk fat and protein concentration ranked oppositely. Daily milk solids yield did not differ among the 3 genotypes. Intake capacity, expressed as DMI per BW, tended to be different among treatments, with JE having the greatest DMI per BW, HF the lowest, and JE × HF being intermediate. Production efficiency, expressed as milk solids per DMI, was higher for JE than HF and JE × HF. Digestive efficiency, expressed as digestibility of dry matter, organic matter, N, neutral detergent fiber, and acid detergent fiber, was higher for JE than HF. In grazing cows (n = 15 per genotype) samples of rumen fluid, collected using a transesophageal sampling device, were analyzed to determine the relative abundance of rumen microbial populations of cellulolytic bacteria, protozoa, and fungi. These are critically important for fermentation of feed into short-chain fatty acids. A decrease was observed in the relative abundance of Ruminococcus flavefaciens in the JE rumen compared with HF and JE × HF. We can deduce from this study that the JE genotype has greater digestibility and a different rumen microbial population than HF. Jersey and JE × HF cows had a proportionally greater GIT weight than HF. These differences are likely to contribute to the production efficiency differences among genotypes previously reported.
    • Genetic parameters of dairy cow energy intake and body energy status predicted using mid-infrared spectrometry of milk

      McParland, Sinead; Kennedy, Emer; Lewis, Eva; Moore, Stephen; McCarthy, Brian; O'Donovan, Michael; Berry, Donagh; Department of Agriculture, Food and the Marine, Ireland; European Commission; Marie Curie project International Research Staff Exchange Scheme SEQSEL; et al. (Elsevier for American Dairy Science Association, 2014-12)
      Energy balance (EB) and energy intake (EI) are heritable traits of economic importance. Despite this, neither trait is explicitly included in national dairy cow breeding goals due to a lack of routinely available data from which to compute reliable breeding values. Mid-infrared (MIR) spectrometry, which is performed during routine milk recording, is an accurate predictor of both EB and EI. The objective of this study was to estimate genetic parameters of EB and EI predicted using MIR spectrometry. Measured EI and EB were available for 1,102 Irish Holstein-Friesian cows based on actual feed intake and energy sink data. A subset of these data (1,270 test-day records) was used to develop equations to predict EI, EB, and daily change in body condition score (ΔBCS) and body weight (ΔBW) using the MIR spectrum with or without milk yield also as a predictor variable. Accuracy of cross-validation of the prediction equations was 0.75, 0.73, 0.77, and 0.70 for EI, EB, ΔBCS, and ΔBW, respectively. Prediction equations were applied to additional spectral data, yielding up to 94,653 records of MIR-predicted EI, EB, ΔBCS, and ΔBW available for variance component estimation. Variance components were estimated using repeatability animal linear mixed models. Heritabilities of MIR-predicted EI, EB, ΔBCS, and ΔBW were 0.20, 0.10, 0.07, and 0.06, respectively; heritability estimates of the respective measured traits were 0.35, 0.16, 0.07, and 0.08, respectively. The genetic correlation between measured and MIR-predicted EI was 0.84 and between measured and MIR-predicted EB was 0.54, indicating that selection based on MIR-predicted EI or EB would improve true EI or EB. Genetic and phenotypic associations between EI and both the milk production and body-change traits were generally in agreement, regardless of whether measured EI or MIR-predicted EI was considered. Higher-yielding animals of higher body weight had greater EI. Predicted EB was negatively genetically correlated with milk yield (genetic correlation = −0.29) and positively genetically correlated with both milk fat and protein percent (genetic correlation = 0.17 and 0.16, respectively). Least squares means phenotypic EI of 198 animals stratified as low, average, and high estimated breeding values for MIR-predicted EI (animal phenotypes were not included in the genetic evaluation) were 154.3, 156.0, and 163.3 MJ/d, corroborating that selection on MIR-predicted EI will, on average, result in differences in phenotypic true EI.
    • Genomic prediction of crown rust resistance in Lolium perenne

      Arojju, Sai Krishna; Conaghan, Patrick; Barth, Susanne; Milbourne, Dan; Casler, M.D.; Hodkinson, Trevor R; Michel, Thibauld; Byrne, Stephen L.; Department of Agriculture, Food and the Marine, Ireland; Marie Sklodowska-Curie; et al. (Biomed Central, 29/05/2018)
      Background Genomic selection (GS) can accelerate genetic gains in breeding programmes by reducing the time it takes to complete a cycle of selection. Puccinia coronata f. sp lolli (crown rust) is one of the most widespread diseases of perennial ryegrass and can lead to reductions in yield, persistency and nutritional value. Here, we used a large perennial ryegrass population to assess the accuracy of using genome wide markers to predict crown rust resistance and to investigate the factors affecting predictive ability. Results Using these data, predictive ability for crown rust resistance in the complete population reached a maximum of 0.52. Much of the predictive ability resulted from the ability of markers to capture genetic relationships among families within the training set, and reducing the marker density had little impact on predictive ability. Using permutation based variable importance measure and genome wide association studies (GWAS) to identify and rank markers enabled the identification of a small subset of SNPs that could achieve predictive abilities close to those achieved using the complete marker set. Conclusion Using a GWAS to identify and rank markers enabled a small panel of markers to be identified that could achieve higher predictive ability than the same number of randomly selected markers, and predictive abilities close to those achieved with the entire marker set. This was particularly evident in a sub-population characterised by having on-average higher genome-wide linkage disequilibirum (LD). Higher predictive abilities with selected markers over random markers suggests they are in LD with QTL. Accuracy due to genetic relationships will decay rapidly over generations whereas accuracy due to LD will persist, which is advantageous for practical breeding applications.
    • Grassland Phosphorus and Nitrogen Fertiliser Replacement value of Dairy Processing Dewatered Sludge

      Ashekuzzaman, S.M.; Forrestal, Patrick; Richards, Karl G.; Daly, Karen; Fenton, Owen; Enterprise Ireland; Dairy Industry Partners; TC2014 0016 (Elsevier, 21-11-20)
      Dairy processing sludge is currently a bio-based fertiliser being spread to grassland without knowledge pertaining to its phosphorus (P) or nitrogen (N) fertiliser replacement value. This creates uncertainty of desired crop yield achievement and unproductive nutrient recycling and also poses a great challenge to the dairy milk processing industry in promoting their food processing by-product as valuable recyclable fertiliser. Therefore four representative samples, i.e. two activated sludge (aluminium-precipitated (Al-sludge) and iron-precipitated (Fe-sludge)), and two lime-stabilised calcium-precipitated sludge (Ca1- and Ca2-sludge), were examined at field scale to assess P and N availability for crop yield and uptake in comparison to reference mineral fertilisers over one seasonal year. The field plots were set-up on a light textured clay loam soil within the optimum plant available P (Morgan's soil P index 3, i.e. medium / adequate soil P level) in two separate adjoining areas consisting of P and N availability experiments. Each experiment consisted of 40 plots (each 8×2 m2) of 10 treatments with 4 replications arranged in a randomised complete block design. All dairy sludge (40 kg-P ha−1) and mineral P treatments (rates 0–50 kg-P ha−1) produced similar yields and uptake, and crop P was not affected by sludge applications despite the presence of high Al, Ca and Fe. During the experiment there was no significant change in P index (stayed at index 3) indicating that no treatment caused a decline in P into index 2 (i.e. low soil P level), therefore replacing P removed by the crop. The only change in Morgan's P was observed in the Ca-sludge treatments, but this was due to Morgan's reagent overestimating plant available P in high Ca conditions. From N trial plots a significantly higher grass yield and N uptake was observed for Fe and both Ca-type sludge applied plots than the control (zero N) plot during the 1st harvest, while no statistical difference observed in the subsequent harvests (up to 4th harvesting). The N fertiliser replacement value (derived from mineral N response) of sludge samples was observed to be in the order of Fe (54%)>Ca2 (25%)>Ca1 (22%)>Al (8%) with greater promise of N fertiliser efficiency of Fe and Ca types. Overall these bio-based sludges show promise in recycling P and N for grassland application but longer term trials in other soil types considering other environmental aspects (losses to soil, water and air) can further optimize the management of dairy sludge as an alternative to chemical fertiliser.
    • Grazing and ensiling of energy-rich grasses with elevated sugar contents for the sustainable production of ruminant livestock (Acronym: SweetGrass)

      O'Kiely, Padraig; Conaghan, Patrick; Howard, H.; Moloney, Aidan P; Black, Alistair D; European Union; QLK5-CT-2001-0498 (Teagasc, 2005-09-01)
      Permanent grassland dominates the Irish landscape and for many decades perennial ryegrasses have been the main constituent in seed mixtures for grassland.
    • Grazing of Dairy Cows in Europe—An In-Depth Analysis Based on the Perception of Grassland Experts

      van den Pol-van Dasselaar, Agnes; Hennessy, Deirdre; Isselstein, Johannes (MDPI AG, 2020-02-04)
      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 period 2010–2019. Both surveys and focus group meetings were used. There is a clear trend of reduced grazing in Europe. Since grazing is valued by different stakeholders and provides many ecosystem services, solutions to the constraints to grazing must be found. Constraints can be divided into region specific constraints, farm specific constraints and farmer specific constraints. The solutions include developing new knowledge, bringing the knowledge already available to practice and rewarding farmers for grazing as a service to society. If grazing is not supported, it will further decline. However, a joined endeavour has the potential to make a significant difference in transforming grass-based production systems and stimulating grazing.
    • Grazing of dairy cows on pasture versus indoor feeding on total mixed ration: Effects on low-moisture part-skim Mozzarella cheese yield and quality characteristics in mid and late lactation

      Gulati, Arunima; Galvin, Norann; Hennessy, Deirdre; McAuliffe, Stephen; O'Donovan, Michael; McManus, Jennifer J.; Fenelon, Mark; Guinee, Timothy P.; Department of Agriculture, Food and the Marine, Ireland; Dairy Levy Research Trust; et al. (Elsevier for American Dairy Science Association, 2018-08-16)
      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, calving date, and pre-experimental milk yield and milk solids yield. Each herd was allocated to 1 of the following feeding systems: grazing on perennial ryegrass (Lolium perenne L.) pasture (GRO), grazing on perennial ryegrass and white clover (Trifolium repens L.) pasture (GRC), or housed indoors and offered total mixed ration (TMR). Mozzarella cheese was manufactured on 3 separate occasions in ML and 4 in LL in 2016. Feeding system had significant effects on milk composition, cheese yield, the elemental composition of cheese, cheese color (green to red and blue to yellow color coordinates), the extent of flow on heating, and the fluidity of the melted cheese. Compared with TMR milk, GRO and GRC milks had higher concentrations of protein and casein and lower concentrations of I, Cu, and Se, higher cheese-yielding capacity, and produced cheese with lower concentrations of the trace elements I, Cu, and Se and higher yellowness value. Cheese from GRO milk had higher heat-induced flow and fluidity than cheese from TMR milk. These effects were observed over the entire lactation period (ML + LL), but varied somewhat in ML and LL. Feeding system had little, or no, effect on gross composition of the cheese, the proportions of milk protein or fat lost to cheese whey, the texture of the unheated cheese, or the energy required to extend the molten cheese. The differences in color and melt characteristics of cheeses obtained from milks with the different feeding systems may provide a basis for creating points of differentiation suited to different markets.
    • 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.
    • Irish Grassland Research — main achievements and advancements in the past 60 yrs and where to progress to next

      O’Donovan, Michael; Dillon, P.; Conaghan, Patrick; Hennessy, Deirdre (Teagasc, 2022-02-09)
      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 evaluation, ruminant nutrition, grazing management and silage technology has contributed to increased utilisation of grassland. Annual grass DM production varies from 12.7 to 15.0 t DM/ha based on Department of Agriculture, Food and the Marine grass variety trials. More recent data from PastureBase Ireland indicate that average annual grass production (2020) on efficient dairy and dry stock farms is 13.5 and 10.0 t DM/ha, respectively. Ireland is now one of the world leaders in grassland research, particularly in the area of grazing utilisation, the development and use of grassland databases, decision support systems and grass selection indices for grass varieties. Future pasture-based systems must extend beyond food production to deliver additional benefits to farmers, to consumers and the wider society. Future systems will require more robust grazing animals with healthier functional traits, more diverse swards supporting improved animal performance and require fewer fertiliser and chemical inputs, and will support more biodiversity and enhanced carbon storage.
    • 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.