• A rapid and multi-element method for the analysis of major nutrients in grass (Lolium perenne) using energy-dispersive X-ray fluorescence spectroscopy

      Daly, Karen; Fenelon, A. (Teagasc (Agriculture and Food Development Authority), Ireland, 21/04/2017)
      Elemental analysis of grass (Lolium perenne) is essential in agriculture to ensure grass quality and animal health. Energy-dispersive X-ray fluorescence (EDXRF) spectroscopy is a rapid, multi-element alternative to current methods using acid digestion and inductively coupled plasma optical emission spectrometry (ICP-OES). Percentage phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca), determined from grass samples using EDXRF, were within 0.035, 0.319, 0.025 and 0.061, respectively, of ICP-OES values. Concordance correlation coefficients computed using agreement statistics ranged from 0.4379 to 0.9669 (values close to one indicate excellent agreement); however, the level of agreement for each element depended on the calibrations used in EDXRF. Empirical calibrations gave excellent agreement for percentage P, K and Ca, but moderate agreement for percentage Mg due to a weaker correlation between standards and intensities. Standardless calibration using the fundamental parameters (FP) approach exhibited bias, with consistently lower values reported for percentage P and Mg, when compared with ICP-OES methods. The relationship between the methods was plotted as scatter plots with the line of equality included, and although correlation coefficients indicated strong relationships, these statistics masked the effects of consistent bias in the data for percentage P and Mg. These results highlight the importance of distinguishing agreement from correlation when using statistical methods to compare methods of analysis. Agreement estimates improved when a matching library of grass samples was added to the FP method. EDXRF is a comparable alternative to conventional methods for grass analysis when samples of similar matrix type are used as empirical standards or as a matching library.
    • Rearing calves outdoors with and without calf jackets compared with indoor housing on calf health and live-weight performance

      Earley, Bernadette; Murray, Margaret; Farrell, J.A.; Nolan, Marie-Jean; National Development Plan, 2000-2006 (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
      The objective of this study was to compare the effects of rearing calves outdoors, with and without all-weather calf jackets, with calves reared indoors on calf immunity and animal performance. In February 1999, male Holstein calves (mean (s.e.) weight 55 (1.90) kg) were randomly assigned to one of three treatments (n=30 per treatment): 1) outdoors with jacket, (J; mean age 19 (s.e. 2.0) days); 2) outdoors without jacket (NJ; mean age 19 (s.e. 1.8) days), and 3) indoors on straw (I; mean age 19 (s.e. 1.0) days). Calves received an individual allowance of 25 kg of milk replacer dry matter during the first 42 days with ad libitum access to a concentrate ration from day 0 to 63. The jackets were removed from the calves on day 42. Live-weight gain from day 0 to day 63 of the study was not significantly different between treatments (J, 0.79; NJ, 0.80; I, 0.80 kg). Sixty percent of the J calves and 53% of the NJ calves required four or more antibiotic treatments for respiratory disease while corresponding treatments were required for 97% of the I calves. The incidence of diarrhoea was significantly higher in both outdoor treatments compared to the I treatment. There was no significant difference in white blood cell counts or in serum immunoglobulin concentrations between treatments on days 0, 21, 42 and 63 or in in vitro interferon-γ production on day 63. It is concluded that using calf jackets on calves reared outdoors had no beneficial effect on calf performance or immune status. The incidence of respiratory disease was higher and diarrhoea incidence was lower in calves reared indoors compared with calves reared outdoors. There was no significant difference in incidences of diarrhoea and respiratory disease between the two outdoor treatments.
    • Relationship between live weight and body condition score in Irish Holstein-Friesian dairy cows

      Berry, Donagh P.; Buckley, Frank; Dillon, Pat (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      The objective of this study was to quantify the change in live weight (LWT) per unit change in body condition score (BCS) for Irish Holstein-Friesian dairy cows. Mixed model analyses were performed on 82 948 test-day records of BCS and LWT across 11 075 lactations from 7391 cows, representing 62 commercial and 4 research herds, during the years 1999 and 2000. Factors included in the mixed models were parity, stage of the inter-calving interval and the three-way interaction between herd, year and fortnight of the calendar year at calving. Interactions between the effect of BCS and either parity or stage of the inter-calving interval were included in some models to evaluate the effect of these factors on the relationship between LWT and BCS. A moderate correlation (0.49) existed between BCS and LWT in the complete dataset, but it differed significantly with parity and stage of the inter-calving interval (range 0.36 to 0.59). Analysis of the entire dataset yielded an estimate of 50 kg LWT change per unit change in BCS and this coefficient ranged from 39 kg to 66 kg, depending on parity or the stage of the inter-calving interval. Accurate values of LWT per unit BCS are important input parameters for animal or herd-level biological models designed to evaluate the energy demands of the animal or herd.
    • Requirements of future grass-based ruminant production systems in Ireland

      O'Donovan, Michael; Lewis, Eva; O'Kiely, Padraig (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      There is a renewed interest in grazing systems in many temperate and subtropical regions of the world. This results from lower inflation-adjusted prices, the proposed removal of some subsidies and tariffs, and rising labour, machinery and housing costs. The utilization of grass by grazing should provide the basis of sustainable livestock systems as grazed grass is the cheapest source of nutrients for ruminants. This is very important in the Irish context as there are approximately 130 000 farmers involved in primary production in Ireland and the value of the goods produced was €5.8 billion in 2008. For the future, the key objective for grazing systems is to ensure high grass utilization, allowing increased output per hectare for all sectors. The primary emphasis in grass breeding needs to be focused on (i) seasonal growth pattern as well as overall annual growth, (ii) nutritive value, including digestibility, particularly in the mid-season period, (iii) ensuring a sward canopy structure that is suitable for grazing, and (iv) development of persistent cultivars that perform under farm conditions. Evaluation programmes should also consider including an estimate of production potential at the field as well as at plot level, and evaluation under grazing management systems as well as under mixed grazing/silage management systems. It is difficult to accurately quantify the breeding achievements for grass mainly because its value, whether grazed or conserved, must be indirectly realised through the output of animal product. Grass evaluation and breeding need to better accommodate the requirements of the grazing ruminant. This will necessitate the application of new approaches and knowledge, which will ultimately enable further increases in animal output per hectare to be achieved.
    • The response of sward-dwelling arthropod communities to reduced grassland management intensity in pastures

      Helden, Alvin J.; Anderson, Annette; Finn, John; Purvis, Gordon (Teagasc (Agriculture and Food Development Authority), Ireland, 2015-12-30)
      We compared arthropod taxon richness, diversity and community structure of two replicated grassland husbandry experiments to investigate effects of reduced management intensity, as measured by nutrient input levels (390, 224 and 0 kg/ha per year N in one experiment, and 225 and 88 kg/ha per year N in another). Suction sampling was used to collect Araneae, Coleoptera, Hemiptera and Hymenoptera, with Araneae and Coleoptera also sampled with pitfall trapping. Univariate analyses found no significant differences in abundance and species density between treatments. However, with multivariate analysis, there were significant differences in arthropod community structure between treatments in both experiments. Reducing N input and associated stocking rates, as targeted by agri-environment schemes, can significantly alter arthropod communities but without increasing the number of species present. Other approaches that may be necessary to achieve substantial enhancement of sward arthropod biodiversity are suggested.
    • Response of two-row and six-row barley to fertiliser N under Irish conditions

      Hackett, Richard (Teagasc (Agriculture and Food Development Authority), Ireland, 2016-12-30)
      A range of cultivar types, including two-row and six-row types as well as line and hybrid types, are used for winter barley production in Ireland. There is little information available on the fertiliser nitrogen (N) requirements or the N use efficiency of these different types, particularly under Irish conditions. The objectives of the work presented here were to compare the response to fertiliser N of a two-row line cultivar, a six-row line cultivar and a six-row hybrid cultivar in terms of grain yield and aspects of N use efficiency. Experiments were carried out over three growing seasons, in the period 2012-2014, on a light-textured soil comparing the response of the three cultivars of winter barley to fertiliser N application rates ranging from 0 to 260 kg N/ha. There was no evidence that cultivar type, regardless of whether it was a two-row or six-row line cultivar or a six-row hybrid cultivar, influenced the response to fertiliser N of winter barley. There were some indications that six-row cultivars were less efficient at recovering soil N but used accumulated N more efficiently than the two-row cultivar. This work provided no evidence to support adjustment of fertiliser N inputs to winter barley based on cultivar type
    • Responses of grain yield, biomass and harvest index and their rates of genetic progress to nitrogen availability in ten winter wheat varieties.

      White, E.M.; Wilson, F.E.A. (Teagasc, Oak Park, Carlow, Ireland, 2006)
      Increased yields in winter wheat cultivars have been found to be largely attributable to improved partitioning of biomass to the grain, i.e., higher harvest index. However, there is a biological upper limit to harvest index and therefore breeders need to exploit increased biomass production as the mechanism by which yields are increased. Evidence for improved biomass was sought in experiments conducted over three years (1994 to 1996), at the Plant Testing Station, Crossnacreevy, near Belfast, with 10 varieties of winter wheat introduced over the period 1977 to 1991. Variation in grain yield was more strongly associated with variation in biomass (an increase of 0.78 t/ha in grain yield at 85% dry matter (DM) per 1t/ha increase in biomass at 100% DM; R2 = 0.71) than in harvest index (an increase of 0.1t/ha at 85% DM per percentage point increase in harvest index; R2 = 0.36). When age (= year of first harvest in UK National List trials) of the varieties was taken into account, yield (0.037 t ha−y−; R2 = 0.42) and biomass (0.034 t ha−y−; R2 = 0.31), but not harvest index (0.34%/year; R2 = 0.001), increased as year increased. Genetic gain in yield was smaller without fertiliser N (0.021 t ha−y−; R2 = 0.21) and at 40 kg ha N (0.025 t ha−y−; R2 =0.25) than at 215–250 kg/ha N (0.065 t ha−y−; R2 = 0.39). Theoretically, if the maximum biomass (18.60 t/ha for Rialto), could have been combined with the maximum harvest index (55.3%) in Riband, yield would potentially have been increased by 2.5 t/ha compared with yields for either variety.
    • A review of perennial ryegrass variety evaluation in Ireland

      Grogan, D.; Gilliland, T.J. (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      Official National List (NL) testing of perennial ryegrasses commenced in Ireland at the start of the 1970s with Northern Ireland (NI) having one site as part of the UK NL testing network, and the Republic of Ireland (ROI) using 5 sites. The different testing strategies adopted to achieve sufficient precision for regional Recommended Listing in ROI from a multi-site system and from a single-site system in NI were considered, including the test protocols, use of sequential sowings, timeframes and ‘merit scores’. The precision with which varieties can be discriminated for yield potential was shown to decline at lower trial plot yields. Furthermore, reducing the number of data sets used for decision making was shown to increase the ‘breeder’s risk’ of having an improved variety incorrectly rejected but not the ‘tester’s risk’ of erroneously recommending a variety that was not a clear improvement, because statistical analysis expanded confidence limits. These variety lists initially assessed only yield and persistency, giving a progressive improvement in recommended varieties and despite high genotype-x-environment interaction effects was most clearly evident in spring productivity improvements. The lists have been highly influential in both jurisdictions as almost all agricultural grass seed sales were recommended in ROI or NI, but the overuse of late maturing varieties in the ROI market and declining reseeding levels across Ireland indicated the current limits of this influence. This, and increasing requirements from Irish farmers for improvement in the nutritive value of varieties to support greater dependence on grass for animal production, has led to increased testing for digestibility and other quality parameters. While there is valid scientific evidence that shows that improvements in perennial ryegrass varieties has increased milk and meat production, more detailed information is required to satisfy the specific needs of local farmers. Consequently, a research initiative has been instigated to develop an index that will incorporate all the yield, persistence and quality performances of each recommended variety into a ranking score for a specific herd management system. This guidance should simplify recommendations and better quantify variety improvements in financial terms. It is envisaged that this will encourage an increase in the renewal of Irish pastures, promote selection of varieties based on enterprise-specific value and will continue to enhance the profitability and sustainability of grass-dependent Irish farming as has been achieved since recommended lists were first introduced in Ireland.
    • Review of potential sources and control of thermoduric bacteria in bulk-tank milk

      Gleeson, David E; O'Connell, Aine; Jordan, Kieran; Irish Dairy Levy Research Trust (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Bacteria that contaminate milk include thermoduric bacteria that can survive pasteurisation and subsequently grow in the pasteurised milk or contaminate product. Elimination of thermodurics at milking is not feasible. Therefore, knowledge of their source and strategies for their reduction are important. The major sources of thermodurics in milk are contamination of the teat skin from soil and bedding, and subsequent contamination from deposits that can build up on milking equipment surfaces. Hygiene at milking can reduce the number of bacteria contaminating milk. Teat preparation at milking and a recommended plant cleaning procedure are critical to the prevention of the contamination of milk with thermoduric bacteria.
    • Review of studies on flukicide residues in cows’ milk and their transfer to dairy products

      Power, C.; Sayers, Riona; O'Brien, Bernadette; Furey, A.; Danaher, Martin; Kieran, Jordan; Teagasc Walsh Fellowship Programme (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Flukicides are widely used to treat infestations of liver fluke in dairy cattle. This could result in flukicide residues in milk if animals are improperly treated or if withdrawal periods are not properly observed. The purpose of this review is to summarise the results of studies on depletion of flukicides from milk and the transfer of flukicide residues to dairy products, if present in the milk. As the depletion of flukicide residues from milk of animals treated during lactation was relatively slow, the studies support the view that the dry period (when milk is not being used for human consumption) is the most suitable time for flukicide treatment. Migration of residues to product occurred at different rates, depending on the drug in question. Generally, concentration of flukicides occurred in cheese, butter and skim milk powder. Pasteurisation or heat treatment during spray drying had no impact in reducing residues.
    • Ryegrass breeding - balancing trait priorities

      Stewart, A.; Hayes, R. (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      In all ryegrass breeding programmes it is necessary to select a range of traits within different cultivar types, varying in ploidy and flowering time. The traits selected in ryegrass breeding can be broadly grouped into production traits such as yield, quality and persistency; those seed production traits crucial for delivery of the cultivar, as well as those traits that can benefit the environment, or allow ryegrass to be used for biofuel production. The emphasis placed on each trait will depend on its economic value within the various farming systems where each cultivar will ultimately be used, as well as the potential to make genetic gain in each trait. In all cases multiple trait selection will be required, to develop a cultivar improved for key traits of interest but importantly the cultivar must not have unacceptable performance for any trait. Where the genetic variation is inadequate within perennial ryegrass it may be necessary to enhance ryegrass diversity. In the future this could be achieved through targeted introgression from the closely related Festuca species, or through introduction of genes via genetic modification. Funding of ryegrass breeding internationally will increasingly be subject to the economic success of a few larger seed companies as Government funding for field-based breeding is diminishing and shifting focus to more basic research, often of a molecular nature. Ensuring this expensive basic research and associated molecular technologies are used effectively in ryegrass breeding programmes will remain a challenge when seed companies operating field-based programmes are vulnerable to considerable economic pressure.
    • Scientific appraisal of the Irish grass-based milk production system as a sustainable source of premium quality milk and dairy products

      O'Brien, Bernadette; Hennessy, Deirdre (Teagasc (Agriculture and Food Development Authority), Ireland, 2017-12-29)
      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 the export market and (b) sustainability from the perspectives of people, planet and profit. This paper provides a short review of current scientific evidence in relation to a number of topics, each of which is important in maintaining and developing dairy product quality and the sustainability of the Irish dairy industry. The topics addressed in the paper are as follows: the parameters of milk composition; milk processing; hygiene quality and safety; farm management practices and the regulations that govern such practices; animal health and welfare; environmental impacts; economic implications for farm families and rural communities; and the overall future sustainability of the family-based dairy farm structure.
    • Seasonality of nitrogen uptake, apparent recovery of fertilizer nitrogen and background nitrogen supply in two Irish grassland soils

      Murphy, P. N. C.; O'Connell, K.; Watson, S.; Watson, C. J.; Humphreys, James; Irish National Development Plan; Irish Dairy Levy Research Trust (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Improving fertilizer nitrogen (N) use efficiency is central to sustainable and profitable grassland agriculture. A plot experiment with a control and fertilizer N (calcium ammonium nitrate, 25–50 kg/ha N) applied on nine occasions from February to September 2002 was conducted at two sites in southwest Ireland to assess N uptake and apparent recovery of fertilizer N (ARFN). Apparent recovery of fertilizer N after eight weeks varied from low in February (21%) and March (46%) to high from April to August (69–98%), indicating that high N use efficiency can be achieved in Irish grasslands at these times. Low recovery in spring suggested that N was applied in excess of immediate crop requirements. Note that N uptake and ARFN values from this study are likely to be somewhat conservative, particularly for spring applications. Over the 8 weeks during which growth was monitored, most (70%) of the grass yield and N uptake response to fertilizer N were in weeks 1 to 4 after application; however, a significant (30%) response occurred in weeks 5–8. This suggested that residual N availability following grazing at 4 weeks can be significant and that there may be scope to decrease N application rates in a grazing rotation. This can potentially improve N use efficiency and decrease N surpluses, with associated economic and environmental benefits. Apparent recovery of fertilizer N was closely related to soil temperature, with a 5.8% increase in ARFN with a 1 °C increase in temperature. Background (non-fertilizer) N supply contributed an average of 164 kg/ha per year (49%) taken up by the fertilized sward, highlighting the potential importance of soil N mineralisation to grassland productivity. Note that these results are for one year at two sites and that conditions may vary between years and at other sites and also that the experiment did not reproduce the cumulative effect of repeated fertilizer application over the grazing year.
    • Sinapinic and protocatechuic acids found in rapeseed: isolation, characterisation and potential benefits for human health as functional food ingredients

      Quinn, Leah; Gray, Stephen G.; Meaney, Steven; Finn, Stephen; Kenny, Owen; Hayes, Maria (Teagasc (Agriculture and Food Development Authority), Ireland, 13/12/2017)
      Rapeseed is one of the world’s major oilseeds, and rapeseed oil is produced by pressing of the seeds. This process results in the production of a low-economic-value by-product, rapeseed meal, which is commonly used as animal feed. Rapeseed meal is rich in bioactive phenolic compounds, including sinapinic acid (SA) and protocatechuic acid (PCA). Isolation of these bioactive compounds from a by-product of rapeseed oil production is largely in agreement with the current concept of the circular economy and total utilisation of crop harvest using a biorefinery approach. In this review, current information concerning traditional and novel methods to isolate phenolic compounds – including SA and PCA – from rapeseed meal, along with in vitro and in vivo studies concerning the bioactivity of SA and PCA and their associated health effects, is collated. These health effects include anti-inflammatory, anti-cancer, anti-diabetes activities, along with histone deacetylase inhibition and protective cardiovascular, neurological and hepatic effects. The traditional extraction methods include use of solvents and/or enzymes. However, a need for simpler, more efficient methodologies has led to the development of novel extraction processes, including microwave-assisted, ultrasound-assisted, pulsed electric field and high-voltage electrical discharge extraction processes.
    • Soil cover of tubers and the percentage of green tubers at various inter-row widths

      Bernik, R.; Godesa, T.; Dolnicar, P.; Vucajnk, F. (Teagasc, Oak Park, Carlow, Ireland, 2009)
      In the years 2002, 2003 and 2004, a field trial was conducted involving three inter-row widths (66, 75 and 90 cm) and three potato cultivars (Agria, Bright and Carlingford). Increasing the inter-row width (IRW) increased both the cross-sectional area of the ridge and ridge height measured before the harvest. With an IRW of 66 cm the majority of tubers were located directly under the ridge surface (at a depth of < 5 cm), which resulted in the highest percentage of green tubers among the three IRW values. At the 90 cm IRW, in particular, the vast majority of tubers was distributed deeply in the ridge (at a depth of > 5 cm), thus generating the smallest percentage of green tubers. Compared to the other two cultivars, Carlingford produced tubers distributed at a larger ridge depth and subsequently yielded the lowest percentage of tubers covered with less than 5 cm of soil. On the other hand, Agria had a wider horizontal span of tubers than the other two cultivars.
    • The spatial variation in degree days derived from locational attributes for the 1961 to 1990 period

      Fealy, R.; Fealy, Reamonn; Environmental Protection Agency (Teagasc, Oak Park, Carlow, Ireland, 2008)
      The relationship between degree days and locational attributes for a selection of sites in Ireland were examined in order to objectively extrapolate values for unmeasured locations. While a number of previous researchers have employed similar methodologies in order to map the geographical variation for selected degree-day thresholds, the authors seek to expand on this existing research through the inclusion of a denser network of stations and for a longer time period (1961 to 1990). Degree days were calculated on a daily basis for three selected threshold temperatures, 0 oC, 5 oC, 10 oC, in order to provide a more accurate assessment of the accumulated monthly energy available at each station. The geographical distribution of degree days was then mapped employing a stepwise linear regression which related locational parameters for each station to the calculated monthly accumulations. While none of the selected thresholds are specific to any plant or insect species they are indicative of the likely spatial variation in degree days due to location and elevation. It is intended that the derived spatial distributions will be useful in providing a basis for assessing likely changes in the thermal regime arising as a consequence of climate change over the course of the present century with the associated potential impact on spatial location of arable cropping in Ireland.
    • Studies into the dynamics of perennial ryegrass (Lolium perenne L.) seed mixtures

      Gilliland, T.J.; Hennessy, D.; Griffith, V. (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      The dynamic interactions of four perennial ryegrass seed mixtures sold in Northern Ireland were studied under simulated grazing and conservation managements. Mixture composition was determined as changes in phosphoglucoisomerase isozyme frequencies by calculation from known isozyme frequencies of the component varieties. Mixture productivity was measured over 4 growing seasons and compared with yields predicted from those of the components in monoculture, weighted for their actual proportion in the mixture. No significant differences were found between actual yields for mixtures and their predicted yields, but when these differences were regressed against the heading date range among the varieties in each mixture, a significant relationship was observed. A wide range in heading date among the components of the mixtures was associated with increased yield stability over years and with a declining yield advantage for the mixture compared to its components grown as monocultures. In this aspect, the mixtures showed a more rapid decline under conservation management than under simulated grazing. Mixtures also had a flatter seasonal yield-production profile than their component varieties. Tetraploid components were more aggressive than diploids, though a more open-growing diploid maintained its proportion in the sward better than a dense-growing type and manipulating the sowing ratios could be used to influence final sward composition after 2 years. It was concluded that the differences in heading date range within mixtures had a significant impact on mixture dynamics, with the tetraploid component being the most aggressive.
    • Surveys of cereal diseases in Northern Ireland, 1976 to 2000

      Mercer, P. C.; Ruddock, A. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
      A number of disease surveys was carried out on the three main cereals grown in N. Ireland from 1976 to 2000, namely spring and winter barley and winter wheat. Although not all crops were surveyed in each year, the surveys provide a good picture of changes in disease spectra over the years. The most dramatic change in spring barley disease has been the almost complete disappearance of Blumeria graminis (mildew) and its replacement as the dominant disease by Rhynchosporium secalis (leaf blotch). Leaf-spotting ascribed to physiological causes also became more common in the latter years of the surveys. The disease spectrum of winter barley was more consistent from year to year, with Rhynchosporium secalis as the most common pathogen. Barley yellow dwarf virus was relatively severe in 1984, but in no other years. In winter wheat, there was a major change with the almost complete eclipse of Phaeosphaeria nodorum leaf blotch by Mycosphaerella graminicola (septoria tritici blotch). Gaeumannomyces graminis (take-all) was frequently severe. Surveys of cultivar popularity generally showed a rapid change in varieties over a relatively short time. Surveys of fungicide usage tended to show an increase in numbers of sprays applied, in spite of the fact that commercial pressures should have been acting towards a reduction in spraying.
    • A theoretical and practical analysis of the optimum breeding system for perennial ryegrass

      Conaghan, P.; Casler, M.D. (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      The goal of plant breeding is to effectively and efficiently select for the best phenotypes leading to the development of improved cultivars. The objectives for this review are to describe and critically evaluate breeding methods appropriate to the improvement of perennial ryegrass (Lolium perenne L.) in a long-term breeding programme. The optimum breeding system is dependent on the traits for improvement, and the available physical and human resources. Forage dry matter yield, persistency, disease resistance, nutritional value and seed yield are considered among the most important traits for improvement. Careful consideration should be given to the expression of the trait under the management regime imposed in the breeding programme and under real-world sward conditions in the target sowing region. Recurrent selection programmes for intrapopulation improvement are most appropriate for breeding perennial ryegrass. Three distinct types of recurrent selection may be implemented: (i) phenotypic recurrent selection, (ii) genotypic recurrent selection and (iii) marker-assisted selection. Genotypic recurrent selection will be a necessary part of the breeding system if forage yield is a trait for improvement. Genotypic recurrent selection may be practiced using full-sib or half-sib families, each with their own advantages and disadvantages. Phenotypic recurrent selection in tandem (i.e., within-family selection) or in succession with genotypic recurrent selection should be used to improve traits that have a high-correlation between performance from spaced plants and from sward plots. Genome-wide selection represents the most interesting and exciting potential application of marker-assisted selection, although it remains to be seen how beneficial it will be in practice.
    • Trends, over 14 years, in the ground cover on an unimproved western hill grazed by sheep, and associated trends in animal performance

      Walsh, M.; Hanrahan, J.P.; O'Malley, L; Moles, R. (Teagasc (Agriculture and Food Development Authority), Ireland, 2016-12-14)
      The frequency of individual plant species at ground level and the species composition of the unimproved vegetation on a western hill farm, stocked with Scottish Blackface sheep, were monitored from 1995 to 2008. Performance criteria of the flock that relied totally, or almost totally, on this vegetation for sustenance from 1994 to 2011 were evaluated. The frequency of vegetation increased over time (from 65% to 82% of the surface area; P < 0.05), with a corresponding decline in the frequency of bare soil, thus reducing vulnerability to soil erosion. This increased incidence of vegetation cover reflected increases in ‘other forbs’(P < 0.01), heather(P < 0.05)and grass (P < 0.08).A significant change (P < 0.05) also occurred in the species composition of the vegetation, reflecting an increase in the proportions of ‘other forbs’ (P < 0.05) and heather (P = 0.14), and a decline in the proportion of sedges (P = 0.14). A similar pattern occurred in the two main habitats: blanket bog and wet heath. Annual stocking rate (ewes per hectare, based on actual ewe grazing days) on the unimproved hill grazing averaged 0.9 (0.13 livestock units) per hectare prior to 1999 and 0.78 (0.11 livestock units) per hectare subsequently. There was no trend in weight gain of replacement females while confined to the unimproved hill area between weaning (14 weeks old) and first joining at 18 months of age. A negative trend (P < 0.01) occurred in the pre-weaning growth rate of lambs on the hill. The average number of lambs reared per ewe joined (reflecting fertility, litter size and ewe/lamb mortality) was 1.0, and this showed no evidence of change over time. The study flock performed 10% to > 60% better, depending on the variable, than similar flocks in the National Farm Survey at comparable stocking rates. A well-defined rational management system can sustain a productive sheep enterprise on unimproved hill land without negative consequences for the frequency or composition of the vegetation.