• The effect of grass genotype and spring management on the nutritive value of mid-summer ryegrass swards

      O'Donovan, Michael; Hurley, Grainne; Gilliland, Trevor (Teagasc, 2008-07-01)
      The objective of this project was to investigate the environmental, morphological and management factors that control reproductive initiation and development in Lolium perenne L. (perennial ryegrass) and their influence on mid-season sward quality. These factors were assessed on eight perennial ryegrass cultivars through spaced plant and plot studies. The first part of this project determined the effects of meteorological conditions and latitude on reproductive initiation and ear emergence of cultivars over two consecutive years. It was concluded that the critical day length requirement for reproductive initiation varies between perennial ryegrass cultivars and is independent of latitude and the normal range of conditions. Using this information a strong correlation (r2 = 0.94) was found between the critical day length for ear initiation and the ten year standardised ear emergence dates of the cultivars. This correlation was sufficiently robust to predict the critical initiation date for any perennial ryegrass cultivar on a UK recommended list or on the EU common catalogue by using their heading dates from the UK Plant Breeders Rights trials at Crossnacreevy. Large variation was observed for secondary initiation and re-heading between cultivars of similar and varying maturity, which is a major factor reducing mid-season sward quality. The propensity for initiation of re-heading was strongly influenced by the severity of defoliation (intense to very lax), but there was also evidence to suggest that critical day length post-solstice, may determine the latest date when further reproductive initiation could occur. Differences in plant growth modes were clearly evident as the sward structure, plant morphology and nutritive compositions differed significantly between cultivars during the mid-season. Defoliation management also significantly affected mid-season sward structure, morphology and nutritive composition. While the effect of defoliation height on the sward physical and chemical compositions was inconclusive, an intensive (30 mm) defoliation resulted in plants returning to a vegetative growth mode earlier compared to a lax (60 mm) defoliation treatment. It was observed that defoliation at a critical growth stage can significantly affect subsequent sward structures. Delaying initial spring defoliation resulted in a greater leaf proportion and swards of greater herbage quality in the plot study. This study, therefore, established the need for more detailed evaluation of cultivars by national testing authorities to allow farmers to select cultivars for grazing use that will optimise animal intake and performance.
    • The effect of Holstein-Friesian genotype and feeding system on selected performance parameters of dairy cows on grass-based systems of milk production in Ireland

      Dillon, Pat; O’Connor, Paula M.; McCarthy, S.; Shalloo, Laurence; Linnane, M.; Berry, Donagh; Buckley, James F.; Mee, John F; Horan, Brendan (Teagasc, 2006-01-01)
      The overall objective of this project was to assess, the effect of strain of Holstein-Friesian dairy cow, pasture-based feed system (FS) and their interaction on animal performance in terms of milk productivity and lactation profile, body weight (BW), body condition score (BCS), feed intake and energy balance (EB), reproductive performance and overall economic profitability.
    • Effect of Holstein–Friesian genetic group on peripartum and early lactation haematological and acute phase proteins profiles, health and fertility

      Olmos, G.; Boyle, Laura; Horan, Brendan; Berry, Donagh; Sayers, Riona; Hanlon, A.; Mee, John F (Cambridge University Press, 2009-07)
      Pasture-based Holstein–Friesian cows from three genetic groups differing in the Irish ‘Economic Breeding Index’ (EBI) value and genetic background, namely North-American (NA) national average EBI genetic merit (LOW-NA, n542), North-American high EBI genetic merit (HIGH-NA, n542) and New Zealand (NZ) high EBI genetic merit (HIGH-NZ, n542), were studied. These genetic groups have been selected in different environments: pasture for NZ and confinement for NA. The objective was to determine the effect of genetic group on haematological and acute phase proteins profiles (white blood cell (WBC) counts, red blood cell (RBC) counts, acute phase proteins: serum amyloid A (SAA) and haptoglobin), health (rectal temperature (RT), clinical mastitis (CM) and somatic cell score), calving performance (stillbirth, calving assistance) and post-partum reproductive parameters (endometritis and ovarian cyclicity). Blood sampling and data recording took place 3 weeks pre-calving up to 7 weeks post-calving. Linear mixed models, logistic regression and generalised estimating equations were used for data analysis. HIGH-NZ animals had the highest ( P,0.05) RBC mean corpuscular volume (50.0 fl), exhibited a different WBC distribution pattern ( P,0.05) and had the lowest ( P,0.05) mean RT (38.48C) for the first 10 days post-calving. These findings suggest enhanced reticulocyte turnover, peripartum response mechanisms and thermoregulation in the HIGH-NZ compared to the other two genetic groups. LOW-NA animals had the highest SAA peak throughout the peripartum period (55.12 mg/l, P,0.05) and a tendency for higher somatic cell scores ( P,0.10) in early lactation. The HIGH-NA animals had the lowest incidence of udder quarter milk sample bacteria at calving, suggesting better udder health when commencing lactation. No differences were detected between genetic groups in calving performance, post-partum reproductive parameters or CM in the first 42 days post-calving. These results suggest that while inherited peripartum adaptation strategies have been developed by the different genetic groups selected in different environments (pasture5NZ v. confinement5NA), such differences have minimal impact on peripartum clinical health.
    • Effect of stocking rate and animal genotype on dry matter intake, milk production, body weight, and body condition score in spring-calving, grass-fed dairy cows

      Coffey, E. L.; Delaby, Luc; Fitzgerald, S.; Galvin, Norann; Pierce, K.M.; Horan, Brendan; Dairy Research Ireland (Elsevier, 2017-06-28)
      The objective of the experiment was to quantify the effect of stocking rate (SR) and animal genotype on milk production, dry matter intake (DMI), energy balance, and production efficiency across 2 consecutive grazing seasons (2014 and 2015). A total of 753 records from 177 dairy cows were available for analysis: 68 Holstein-Friesian and 71 Jersey × Holstein-Friesian (JxHF) cows each year of the experiment under a pasture-based seasonal production system. Animals within each breed group were randomly allocated to 1 of 3 whole-farm SR treatments defined in terms of body weight per hectare (kg of body weight/ha): low (1,200 kg of body weight/ha), medium (1,400 kg of body weight/ha), and high (1,600 kg of body weight/ha), and animals remained in the same SR treatments for the duration of the experiment. Individual animal DMI was estimated 3 times per year at grass using the n-alkane technique: March (spring), June (summer), and September (autumn), corresponding to 45, 111, and 209 d in milk, respectively. The effects of SR, animal genotype, season, and their interactions were analyzed using mixed models. Milk production, body weight, and production efficiency per cow decreased significantly as SR increased due to reduced herbage availability per cow and increased grazing severity. As a percentage of body weight, JxHF cows had higher feed conversion efficiency, higher DMI and milk solids (i.e., kg of fat + kg of protein) production, and also required less energy intake to produce 1 kg of milk solids. The increased production efficiency of JxHF cows at a similar body weight per hectare in the current analysis suggests that factors other than individual cow body weight contribute to the improved efficiency within intensive grazing systems. The results highlight the superior productive efficiency of high genetic potential crossbred dairy cows within intensive pasture-based milk production systems at higher SR where feed availability is restricted.
    • The effect of target postgrazing height on sward clover content, herbage yield, and dairy production from grass-white clover pasture

      Phelan, Paul; Casey, Imelda A.; Humphreys, James; Department of Agriculture, Food and the Marine; Teagasc Walsh Fellowship Programme; RSF 07-511 (Elsevier, 2013-01-16)
      White clover (Trifolium repens) is an important legume for grazed grassland that can increase the profitability and environmental sustainability of milk production. Previous experiments on mown grass-clover plots suggest that low postgrazing heights (PGH) can increase sward clover content and herbage production. However, this has not been tested in actual strip or rotational grazing systems with dairy cows. Furthermore, lowering PGH in grass-only swards (typically perennial ryegrass without white clover) has previously been associated with reduced milk yields per cow. The objective of this experiment was to investigate the effect of PGH by dairy cows on clover content, herbage production, and milk production from strip-grazed grass-white clover swards in Ireland. Three target PGH treatments of 4, 5, and 6 cm were in place for entire grazing seasons (February to November) for 3 consecutive years (2007 to 2009). Each treatment had a mean of 21 Holstein-Friesian dairy cows that strip-grazed a mean annual area of 10.2 ha. Postgrazing height was measured twice a day with a rising plate meter, and cows were moved to the next strip once the target PGH was reached. Annual fertilizer nitrogen input was 90 kg of N/ha for each treatment. The PGH treatment did not significantly affect annual milk yield (6,202 kg/cow), solids-corrected milk yield (6,148 kg/cow), fat, protein, or lactose yields (265, 222, and 289 kg/cow, respectively), cow liveweight (592 kg) or body condition score (3.01). The PGH treatment also had no significant effect on sward white clover content (196 g/kg). However, herbage production of both grass and clover were significantly higher with the 4-cm PGH treatment compared with the 6-cm treatment. Mean annual herbage yields were 11.1, 10.2, and 9.1 t of organic matter (OM)/ha for the 4-, 5-, and 6-cm PGH treatments, respectively. The lower herbage production in the 6-cm PGH treatment resulted in lower annual silage production, greater housing requirements, and a substantially higher net silage deficit (−1,917 kg of OM/cow) compared with the 5- or 4-cm treatments (−868 and −192 kg of OM/cow, respectively). Grazing to a PGH of 4 cm is therefore recommended for grass-white clover swards.
    • The effect of water-soluble carbohydrate concentration and type on in vitro rumen methane output of perennial ryegrass determined using a 24-hour batch-culture gas production technique

      Purcell, Peter J; Boland, T.M.; O'Kiely, Padraig; Department of Agriculture, Food and the Marine; RSF 07 517 (Teagasc (Agriculture and Food Development Authority), Ireland, 2014)
      The objective of this study was to examine the effects of water-soluble carbohydrate (WSC) concentration and type on the in vitro rumen methane (CH4) output of perennial ryegrass (PR) using a 24-hour batch-culture gas production technique. Dried and milled PR was incubated either alone (PR-O) or with added sucrose (PR-S), inulin (PR-I), or sucrose plus inulin (PR-S+I; sucrose:inulin ratio of 1:4) in sealed glass bottles [0.5 g total substrate dry matter (DM) per bottle] at 39 °C for 24 hours with buffered rumen fluid. The WSC types were added (except for PR-O) so that the WSC concentration in each fermentation bottle at the start of the incubation was either 180 (i.e., PR-O), 225, 270, 315, or 360 g/kg of total substrate DM incubated. There were linear decreases in CH4 output per gram of DM disappeared (CH4/ivDMD) and per mmol of total volatile fatty acid output (CH4/tVFA) with increasing WSC concentration in the incubated substrate. The WSC type had no effect on in vitro rumen CH4 output. It is concluded that since CH4/ivDMD and CH4/tVFA were reduced by increasing the concentration of WSC incubated with PR, it would be worthwhile to undertake in vivo experiments to examine these effects on in vivo CH4 emissions per unit of animal product.
    • Effects of breed type, silage harvest date and pattern of offering concentrates on intake, performance and carcass traits of finishing steers

      Cummins, B.; Keane, Michael G.; O'Kiely, Padraig; Kenny, David A.; Teagasc Walsh Fellowship Programme (Teagasc, Oak Park, Carlow, Ireland, 2007)
      The objective of this experiment was to investigate the effects and interactions of breed type, silage harvest date and pattern of offering concentrates on intake, performance and carcass traits of finishing steers. Seventy-two steers (36 Friesian and 36 beef cross) were blocked on weight within breed type and assigned to a pre-experimental slaughter group or to one of 4 dietary treatments in a 2 (breed type) 2 (early- or late- cut silage) 2 (flat rate or varied pattern of offering concentrates) factorial arrangement of treatments. The flat-rate feeding pattern was silage ad libitum plus 5 kg concentrates per head daily to slaughter. The varied feeding pattern was silage only for 79 days followed by concentrates ad libitum to slaughter. All animals were slaughtered together after 164 days when the groups on the two feeding patterns had consumed the same total quantity of concentrates. Friesians had a higher (P < 0.001) silage dry matter (DM) intake and a higher (P < 0.01) total DM intake than the beef crosses. Live-weight gain was similar for both breed types but the beef-cross animals had a higher (P < 0.001) kill-out proportion, higher (P < 0.01) carcass gain, and better (P < 0.001) carcass conformation than the Friesians. The beef-cross type also had a higher (P < 0.001) proportion of muscle and a lower (P < 0.001) proportion of bone in the carcass. Silage harvest date had no effect on silage or total DM intakes but the early-cut silage did result in higher (P < 0.01) carcass gain. Animals on the varied feeding pattern consumed less (P < 0.01) silage DM and less (P < 0.001) total DM than those on the flat rate feeding pattern. Live-weight gain and carcass gain were similar for the two feeding patterns. It is concluded that Friesians had a higher intake, but had lower carcass gain than the beef-cross type. Animals on the early-cut silage had higher carcass gain than those on the late-cut silage. The varied feeding pattern resulted in lower DM intake but efficiency of feed energy utilisation was similar for both feeding patterns. Interactions were generally not statistically significant.
    • Effects of extended grazing during mid, late or throughout pregnancy, and winter shearing of housed ewes, on ewe and lamb performance

      Keady, Tim; Hanrahan, James P; Flanagan, S. (Teagasc, Oak Park, Carlow, Ireland, 2007)
      A flock of March-lambing ewes was used to evaluate the effects of (i) extended (deferred, winter) grazing of pasture during mid, late or throughout pregnancy, and (ii) winter shearing of ewes housed during mid and late pregnancy, on lamb birth weight and subsequent growth to weaning. Ewes (n = 265) were allocated at random to five treatments for the period from 7 December (~ day 47 of pregnancy) to lambing. The treatments were: housed shorn (HS), housed unshorn (HU), grazing throughout (EG), grazing to 20 January followed by housing (EGH), housed to 20 January followed by grazing (HEG). From 1 March to lambing the HEG and EG ewes were dispersed on the paddocks intended for grazing post lambing. All ewes were offered a concentrate supplement during the final 6 weeks of pregnancy. Housed ewes were offered grass silage while ewes on extended grazing were allocated 1.3 kg herbage dry matter per head per day from swards that had been closed for approximately 10 weeks. Ewes plus lambs (except triplet-rearing ewes which were grazed separately) from all treatments were grazed together post lambing, grouped according to lambing date. For treatments HS, HU, EGH, HEG and EG gestation lengths were 147.0, 145.6, 146.3, 146.6 and 146.9 (s.e. 0.34, P < 0.001) days, lamb birth weights were 4.9, 4.3, 4.4, 4.6 and 5.0 (s.e. 0.10, P < 0.001) kg, and lamb weaning weights were 34.6, 32.1, 33.3, 33.8 and 34.9 (s.e. 0.66, P < 0.001) kg, respectively. Extended grazing in mid and late pregnancy resulted in 35% and 65%, respectively, of the increase in lamb birth weight associated with extended grazing throughout. Treatment effects on lamb birth weight were associated with those on weaning weight (P < 0.01, R2 = 0.93). It is concluded that extended grazing or shearing of housed ewes increased lamb birth weight and subsequent weaning weight. The increased lamb birth weight from deferred grazing in mid pregnancy was probably due to improved protein utilisation from the grazed herbage. Meanwhile, the increased
    • Effects of fertiliser nitrogen rate to spring grass on apparent digestibility, nitrogen balance, ruminal fermentation and microbial nitrogen production in beef cattle and in vitro rumen fermentation and methane output

      O'Connor, Alan; Moloney, Aidan P; O'Kiely, Padraig; Boland, T. M.; McGee, Mark; Teagasc Walsh Fellowship Programme; Department of Agriculture, Food and the Marine; 11/S/105 (Elsevier, 2019-06-06)
      The effects of two fertiliser nitrogen (N) application rates - 15 (LN) or 80 (HN) kg N/ha - to Lolium perenne dominant swards in spring, on grass dry matter (DM) intake, digestion, rumen fermentation, microbial N production and N-balance in beef cattle, and in vitro fermentation and methane production were studied. Sixteen Charolais steers with a mean live weight (s.d.) of 475 (18.4) kg, were used in a completely randomised block design experiment and offered zero-grazed grass harvested 21-d post N application. The same grass was incubated in an eight-vessel RUSITEC in a completely randomised block design experiment. The HN treatment had a 540 kg/ha higher grass DM yield, and a 20 g/kg DM higher crude protein (CP) concentration compared to LN. There was no difference (P > 0.05) in DM intake, or in vivo DM, organic matter (OM) and N digestibility between treatments. Rumen fermentation variables pH, lactic acid, ammonia (NH3) and total volatile fatty acid (VFA) concentration were similar (P > 0.05) for both treatments. Nitrogen intake was 19 g/d higher (P < 0.05) for HN compared to LN. Total and urine N loss was 16 and 14 g/d greater (P < 0.05), respectively, for HN compared to LN, but faecal N loss did not differ (P > 0.05) between treatments. The quantity of N retained and N-use efficiency did not differ (P > 0.05) between LN and HN. Plasma urea concentration was 1 mmol/L greater (P < 0.05) for HN compared to LN. Estimated microbial N production was greater (P < 0.05) for HN compared to LN. In vitro NH3 concentrations were higher (P < 0.05) for HN compared to LN, whereas in vitro rumen pH, lactic acid and VFA concentrations and molar proportions did not differ (P > 0.05) between HN and LN. In vitro methane and total gas output were not different (P > 0.05) between treatments. Reducing fertiliser N application rate to grass in spring reduced total and urinary N excretion, which has environmental benefits, with no effects on in vitro methane output.
    • Effects of pre-transport fasting on the physiological responses of young cattle to 8-hour road transport

      Earley, Bernadette; Fisher, A.D.; O'Riordan, Edward G. (Teagasc, Oak Park, Carlow, Ireland, 2006)
      The effects of fasting animals for 8 h prior to an 8-h road journey and their ability to cope with the stress of transport were investigated. The treatments were: 1) fasted and then transported (n=20); 2) non-fasted and transported (n=18); 3) non-fasted at grass (n=18); 4) fasted then fasted (n=18), and 5) non-fasted then fasted (n=18). There was no significant difference in rectal body temperature, pre- or post-transport, or live weight among treatments on days 0 (pre-transport), 1, 4 or 10 (post-transport). The ambient relative humidity and temperature of the outside environment ranged from 82.8 to 99.8% and 9.9 to 14.5 oC, respectively. Holstein × Friesian bulls (230 kg) undergoing an 8-h transportation at stocking densities of 0.82 m2/animal showed physiological and haematological responses that were within normal referenced ranges. Animals that were fasted for 8 h and transported lost 9.4% of live weight while non-fasted transported animals lost 7.2%. The control non-fasted animals remaining at grass gained 2% of live weight. Animals that were fasted continuously but not transported and the initially non-fasted control animals that were subsequently fasted for 9 h lost 6.1% and 6.2% of live weight, respectively. There was no significant change in concentrations of globulin, glucose, urea, haemoglobin or fibrinogen, or in haematocrit percentage before or after transport. Transport reduced lymphocyte percentage (P < 0.001) and increased neutrophil percentage (P < 0.001) in the fasted and non-fasted animals. Following transport, protein concentration was greater (P ≤0.001) in the fasted and transported animals than in the non-fasted animals at grass and haptoglobin concentrations were higher (P ≤0.001) in the fasted plus transported animals than the controls at grass. In conclusion, from the physiological and haematological measurements, an 8-h journey time, even without access to feed for 8 h prior to transport did not appear to impact negatively on animal welfare.
    • Effects of transporting bulls at different space allowances on physiological, haematological and immunological responses to a 12-h journey by road

      Earley, Bernadette; O'Riordan, Edward G. (Teagasc, Oak Park, Carlow, Ireland, 2006)
      The effects of space allowance during transportation on physiological, haematological and immunological responses in nine-month old bulls (250 kg) were assessed before and after a 12-h road journey. Following transport, animals transported at a spatial allowance of 1.27 m2 had higher (P ≤0.001) non-esterified fatty acid concentrations than control. The stimulated production of interferon-, in response to concanavalin-A and keyhole limpet haemocyanin, and plasma cortisol were not different at the 0.85 m2 and 1.27 m2 stocking densities. Glucose and albumin concentrations were higher (P ≤0.001) post-transport in all transported animals than control. The percentage lymphocytes was reduced (P ≤0.001) and neutrophil percentage and the number of neutrophils were increased (P ≤0.001) in all transported treatments. There were no changes (P 0.05) in monocyte numbers, monocyte percentage or platelet numbers following transportation. The haematocrit values were higher (P ≤0.001) in the transported treatments while RBC numbers were higher (P ≤0.001) in the animals transported at a spatial allowance of 1.27 m2 than control. Protein, globulin, urea and lactate concentrations, and white blood cell numbers were not changed at any time during the study. The concentration of -hydroxybutyrate was lower (P ≤0.001) in all animals following transport. Plasma haptoglobin concentrations were unchanged following transportation while plasma fibrinogen concentrations were reduced in all transported treatments. There were no differences among treatments in rectal temperature or live weights pre- and post-transport. The results indicate that within the conditions of the study, there was no welfare advantage in transporting bulls at 1.27 m2 versus the standard spatial allowance of 0.85 m2 on a 12-h road journey.
    • An evaluation of earth banked tanks for slurry storage

      Scully, Heather; Gleeson, Timothy; Purcell, Patrick J.; O’Riordan, Edward G.; Long, Mike; Crosse, Seamus (Teagasc, 2006-09-01)
      This study examines the feasibility of using earth-banked tanks (EBT’s) as an alternative and economical means of winter storage for animal and other farmyard wastes. The study contains a detailed literature review on the subject, the results of a series of laboratory-scale experiments, field studies and a predictive model of the transport process through the soil liner of an earth-banked tank.
    • Evaluation of Lolium perenne L. cv. AberDart and AberDove for silage production

      Conaghan, Patrick; O'Kiely, Padraig; Howard, H.; O'Mara, Frank P.; Halling, M.A.; European Union; Teagasc Walsh Fellowship Programme; QLK5-CT-2001-0498 (Teagasc, Oak Park, Carlow, Ireland, 2008)
      The objective of this study was to assess the value, for silage production, of intermediateheading Lolium perenne L. cultivars, AberDart and AberDove (diploid), bred for increased water-soluble carbohydrate (WSC) concentrations, relative to four control cultivars (Fennema, AberElan and Spelga (diploid), and Greengold (tetraploid)). Cultivars were evaluated for forage dry matter (DM) yield, ground cover and indirect laboratory measures of nutritional value and ensilability over 3 harvest years within intensive silage-production systems. AberDove was the most desirable diploid for silage production producing on average 316 kg/ha higher (2%) DM yield per annum, having a 10 g/kg higher (1%) dry matter digestibility (DMD) and, based primarily on a 6 g/L higher (19%) concentration of WSC expressed in the aqueous extract (WSCAE), offered the greatest potential to produce well preserved silage. Ensiling AberDart compared to the diploid controls offered a slightly greater probability of producing well preserved silage based on a modest increase of 2 g/L (6%) in WSCAE concentration. The dilemma for silage production is that AberDart, on average produced 558 kg/ha less (4%) DM yield per annum but had a greater (1%) DMD of 6 g/kg than the diploid controls. The tetraploid control had, on average, 13 and 8 g/kg higher (2% and 1%, respectively) DMD than AberDart and AberDove, but at a cost of lower ensilability with lower (6% and 21%, respectively) WSCAE values of 2 and 6 g/L. In its favour, the tetraploid control outyielded AberDart by, on average, 917 kg/ha DM per annum (7%) and produced comparable yields to AberDove. Final ground cover ratings were high (≥ 95%) for all cultivars. Evaluation of nutritional value and ensilability offers further grounds to differentiate and select cultivars for animal production potential.
    • Evaluation of the n-alkane technique for estimating herbage dry matter intake of dairy cows offered herbage harvested at two different stages of growth in summer and autumn

      Wright, Marliene; Lewis, Eva; Garry, B.; Galvin, Norann; Dunshea, Frank; Hannah, M.C.; Auldist, Martin J.; Wales, W.J.; Dillon, Pat; Kennedy, Emer; et al. (Elsevier, 2018-11-10)
      The n-alkane technique for estimating herbage dry matter intake (DMI) of dairy cows was investigated in this experiment. Eight Holstein-Friesian dairy cows were offered perennial ryegrass ad libitum that had been harvested at two different herbage masses and during two different seasons, in order to assess the effect of herbage mass and season on the accuracy of the n-alkane technique. Two pre-harvested herbage mass treatments (low, target 1500 kg DM/ha versus high, target 4000 kg DM/ha, measured above 4 cm), were investigated in a crossover factorial arrangement within each of two seasons (summer versus autumn), in Ireland. Each season consisted of two periods, each 12 days in length. Cows were housed in individual metabolism stalls to allow for accurate determination of measured DMI. Herbage DMI was estimated, with the n-alkane technique, by dosing cows twice daily with a C32 n-alkane. Pre-harvest herbage mass and season did not affect the n-alkane estimated DMI, although lack of season and herbage mass effects may have been masked by variation that occurred between swards within the same herbage mass and season. However, there were a number of differences between summer and autumn in the fecal recovery rates of a number of n-alkanes suggesting that the effect of season requires further investigation prior to the application of recovery rates from literature values when investigating diet selection and botanical composition. Overall, the n-alkane technique provided good estimates of DMI; the discrepancy had a standard deviation due to sward of 1.2 and 1.0 kg DM/cow per day, and hence potential bias of up to twice this, and a measurement error standard deviation of 1.3 and 1.0 kg DM/cow per day, for the C33/C32 and C31/C32 n-alkane pair methods respectively. Two n-alkane pairs were tested, and C33/C32 n-alkane provided the most precise estimates of DMI, compared with the C31/C32 n-alkane pair. This research provides some strong evidence for future use of the n-alkane technique including that the accuracy of the technique has not been influenced by contemporary changes to herbage management, is not affected by seasonal changes, and overall is an accurate and precise technique for estimating DMI.
    • Evaluation of the n-alkane technique for estimating the individual intake of dairy cows consuming diets containing herbage and a partial mixed ration

      Wright, M.M.; Auldist, M.J.; Kennedy, Emer; Dunshea, F.R.; Galvin, N.; Hannah, M.C.; Wales, W.J.; DJPR; Victoria; Dairy Australia (Elsevier BV, 2020-07)
      Estimation of dry matter intake (DMI) using the n-alkane technique was evaluated in lactating dairy cows fed fresh herbage and a partial mixed ration (PMR). Four dietary treatments were investigated in a 2 × 2 factorial experiment using 16 Holstein-Friesian dairy cows. Dietary treatments were combinations of low and high amounts of fresh herbage (8 or 14 kg DM/cow per day) and PMR supplement (6 or 12 kg DM/cow per day). The pre-experimental period was 14 days followed by a 10-day experimental period. Cows were housed in individual metabolism stalls to allow for accurate measurement of DMI and total fecal output. Fecal n-alkane recovery rates were calculated to determine the most accurate corrections for incomplete fecal n-alkane recovery. The n-alkane technique accurately estimated DMI when corrected for incomplete fecal recovery using both published recovery rates and recovery rates calculated in this experiment. The most accurate application of recovery rates was with those calculated for each combination of dietary treatments, compared with using an average recovery rate. This research has important implications for the future use of the n-alkane technique, especially in PMR feeding systems. The discrepancy between estimated (when treatment recovery rates were applied) and measured herbage DMI increased with the amount of herbage offered but was not affected by amount of PMR. It was also found that the recovery rates of all natural n-alkanes increased as the amount of herbage increased. This research demonstrates that the n-alkane technique can be used to accurately estimate individual cow intake when fresh herbage and PMR are offered separately, evidenced by strong Lin’s concordance estimates.
    • An evaluation of two grassland-based systems of mid-season prime lamb production using prolific ewes of two genotypes

      Keady, Tim; Hanrahan, James P; Flanagan, S. (Teagasc, Oak Park, Carlow, Ireland, 2009)
      A 4-year study was undertaken to evaluate the effects of two contrasting management systems [year-round grazing (YRG) and normal seasonal grazing followed by indoor feeding during winter (GWF)] on performance of mid-season lambing ewes. On the GWF system, the annual stocking rate was 14.4 ewes/ha, grass silage was conserved for winter feeding indoors, and the ewes were lambed indoors and were then turned out to pasture. The YRG system was stocked at 10.5 ewes/ha, was grazed during the winter, had outdoor lambing and the animals had access to all the farmlet for summer grazing. The ewes were Belclare and Cheviot × Belclare which were balanced across systems. Mean lambing dates and fertiliser N application rates were 20 and 30 March, and 85 and 92 kg/ha, for the GWF and YRG systems, respectively. Concentrate supplementation during late pregnancy was similar on both systems. For the GWF and YRG systems, litter size, lamb mortality, number of lambs reared, birth weight (kg), weaning weight (kg) and lamb carcass output (kg/ha) were 2.17 and 2.24 (s.e. 0.038), 10.1 and 13.8% (P = 0.05), 1.77 and 1.78 (s.e. 0.042), 4.0 and 4.7 (s.e. 0.05, P < 0.001), 27.9 and 30.8 (s.e. 0.25, P < 0.001) and 469 and 348, respectively. Belclare ewes had a higher litter size (2.34 v 2.07; s.e. 0.038, P < 0.001) and number of lambs reared per ewe joined (1.86 v 1.69; s.e. 0.048, P < 0.01) than the Cheviot × Belclare ewes. There were no significant interactions between system and ewe breed type. It is concluded that the YRG system of prime lamb production was sustainable using prolific ewes but at a reduced stocking rate (−26%) and with greater lamb mortality relative to the GWF system. Ewe genotypes with a mean litter size of up to 2.34 lambs are suitable for both systems. Lamb carcass output of 501 kg/ha was achieved from a primarily grass-based system of mid-season prime lamb production using prolific ewes (Belclare).
    • Factors associated with the financial performance of spring-calving, pasture-based dairy farms

      Ramsbottom, George; Horan, Brendan; Berry, Donagh; Roche, John R. (Elsevier for American Dairy Science Association, 2015-03)
      As land becomes a limiting resource for pasture-based dairy farming, the inclusion of purchased supplementary feeds to increase milk production per cow (through greater dry matter intake) and per hectare (through increased stocking rate) is often proposed as a strategy to increase profitability. Although a plausible proposition, virtually no analysis has been done on the effect of such intensification on the profitability of commercial pasture-based dairy farm businesses. The objective of this study was to characterize the average physical and financial performance of dairy systems differing in the proportion of the cow’s diet coming from grazed pasture versus purchased supplementary feeds over 4 yr, while accounting for any interaction with geographic region. Physical, genetic, and financial performance data from 1,561 seasonal-calving, pasture-based dairy farms in Ireland were available between the years 2008 and 2011; data from some herds were available for more than 1 yr of the 4-yr study period, providing data from 2,759 dairy farm-years. The data set was divided into geographic regions, based on latitude, rainfall, and soil characteristics that relate to drainage; these factors influence the length of the pasture growth season and the timing of turnout to pasture in spring and rehousing in autumn. Farms were also categorized by the quantity of feed purchased; farms in which cows received <10, 11–20, 21–30, or >30% of their annual feed requirements from purchased feed were considered to be categories representative of increasing levels of system intensification. Geographic region was associated with differences in grazing days, pasture harvested per hectare, milk production per cow and per hectare, and farm profitability. Farms in regions with longer grazing seasons harvested a greater amount of pasture [an additional 19 kg of dry matter (DM)/ha per grazing day per hectare], and greater pasture harvested was associated with increased milk component yield per hectare (58.4 kg of fat and 51.4 kg of protein more per tonne of DM pasture harvested/ha) and net profit per hectare (€268/ha more per tonne of DM harvested). Milk yield and yield of milk components per cow and per hectare increased linearly with increased use of purchased feed (additional 30.6 kg of milk fat and 26.7 kg of milk protein per tonne of DM purchased feed per hectare), but, on average, pasture harvested/hectare and net profit/hectare declined (−0.60 t of DM/ha and −€78.2/ha, respectively) with every tonne of DM supplementary feed purchased per hectare. The results indicate an effect of purchased feeds not usually accounted for in marginal economic analyses (e.g., milk to feed price ratio): the decline in pasture harvested/hectare, with the costs of producing the unutilized pasture in addition to the cost of feed resulting in a lower profit. In conclusion, greater milk component yields per cow were associated with increased profit per hectare, and a greater use of purchased feeds was associated with an increase in the yield of milk components. However, on average, increasing yield of milk components through the supply of purchased feeds to pasture-based cows was associated with a decline in pasture harvested per hectare and profitability. The decline in pasture harvested per hectare with increased use of purchased supplements per cow is probably the primary reason for the low milk production response and the failure to capitalize on the potential benefits of purchased supplements, with the associated costs of growing the unutilized pasture, in conjunction with increased nonfeed variable and fixed costs outweighing the increased milk production and revenue from supplementation. Farmers considering intensification through use of purchased supplements to increase the stock-carrying capacity of the farm (i.e., stocking rate) must ensure that they focus on management of pasture and total cost control to capture the potential benefits of supplementary feed use.
    • Factors influencing the conservation characteristics of baled and precision-chop grass silages

      McEniry, Joseph; Forristal, P.D.; O'Kiely, Padraig (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      The composition of baled silage on Irish farms frequently differs from that of comparable precision-chop silage. This paper concerns a field-scale study designed to investigate: (a) the effects of number of layers (2, 4, 6 or 8) of polyethylene stretch film and the duration of storage (7 vs. 18 months) on the conservation characteristics of baled silage, and (b) the conservation characteristics of baled (4 layers of stretch film) and precision-chop silages. All silages were made following three durations of wilting (0, 24 or 48 h). Wilting restricted silage fermentation, with silage pH being highest (P<0.001) and the concentration of fermentation products lowest (P<0.001) for the 48 h wilt treatment. Wrapping bales in only 2 layers of polyethylene stretch film resulted in extensive visible mould growth, but mould growth was practically eliminated by the application of 4 or more layers of film. Silage fermentation characteristics were generally improved by wilting, and by 4 compared to 2 layers of stretch film. Extending the storage duration of baled silage from 7 to 18 months reduced (P<0.001) the concentration of fermentation products and increased in-silo fresh weight losses (P<0.001) and visible mould growth. Whereas 4 layers of conventional stretch film are normally sufficient, 6 layers may be necessary to prevent mould growth when bales of unwilted silage are stored for a second season. Under good farm-management conditions differences observed between baled and precision-chop silages probably result mainly from differences in the concentration of dry matter in herbage at ensiling.
    • The fatty acid profile and stable isotope ratios of C and N of muscle from cattle that grazed grass or grass/clover pastures before slaughter and their discriminatory potential

      Moloney, Aidan P; O'Riordan, Edward G.; Schmidt, Olaf; Monahan, Frank J (Teagasc (Agriculture and Food Development Authority), Ireland, 2018-11-09)
      Consumption of grazed pasture compared to concentrates results in higher concentrations, in beef muscle, of fatty acids considered to be beneficial to human health. Little information is available on the influence of the type of grazed forage. Our objectives were to determine 1) the effect of inclusion of white clover in a grazing sward on the fatty acid profile of beef muscle and 2) the potential of the fatty acid profile and stable isotope ratios of C and N to discriminate between beef from cattle that grazed grass-only or grass/clover swards before slaughter. A total of 28 spring-born Charolais steers grazed from March until slaughter in October, either on a perennial ryegrass (Lolium perenne L.) sward that received approximately 220 kg N/ha or a perennial ryegrass–white clover (Trifolium repens L.) sward that received 50 kg N/ha. The longissimus muscle from cattle finished on grass/clover had a higher (P < 0.05) proportion of C18:2 and C18:3 but a lower (P < 0.05) proportion of conjugated linoleic acid and δ15N value than animals finished on the grass-only sward. Discriminant analysis using the fatty acid data showed that, after cross-validation, 80.7% of grass/clover and 86.1% of grass-only muscle samples were correctly classified. Discriminant analysis using the stable isotope data showed that, after cross-validation, 95.7% of grass/clover and 86.5% of grass-only muscle samples were correctly classified. Inclusion of white clover in pasture is likely to have little effect on healthiness of meat for consumers. However, changes in fatty acids and stable isotopes can be used to distinguish between grass/clover-fed and grass-only-fed beef.
    • Feed intake pattern, behaviour, rumen characteristics and blood metabolites of finishing beef steers offered total mixed rations constituted at feeding or ensiling

      Cummins, B.; O'Kiely, Padraig; Keane, Michael G.; Kenny, David A.; Teagasc Walsh Fellowship Programme (Teagasc, Oak Park, Carlow, Ireland, 2009)
      Two experiments were undertaken. In Experiment 1, behaviour, intake pattern and blood metabolites, were recorded for steers offered total mixed rations (TMR) based on grass silage and concentrates, and constituted either at ensiling (E-TMR) or feedout (F-TMR). Fourteen continental crossbred steers (mean starting weight 505 (s.d. 41.5) kg) were assigned to each of the following eight treatments: grass silage offered ad libitum (SO), E-TMR diets constituted in approximate dry matter (DM) ratios of grass:concentrates of 75:25 (EL), 50:50 (EM) and 25:75 (EH), F-TMR diets constituted in approximate DM ratios of grass silage:concentrates of 75:25 (FL), 50:50 (FM) and 25:75 (FH), and finally concentrates ad libitum (AL). Total DM intake increased linearly (P < 0.001) and the time spent eating and ruminating decreased linearly (P < 0.001) with increasing concentrate proportion. Animals on the F-TMR diets had higher total DM intakes (P < 0.05) and plasma glucose (P < 0.05) and urea (P < 0.001) concentrations than animals on the corresponding E-TMR diets. No effect of method of feed preparation on intake pattern or behaviour was recorded. In Experiment 2, four ruminally cannulated Holstein-Friesian steers of mean initial live weight 630 (s.d. 23.2) kg were used to evaluate rumen characteristics for four of the above diets (FL, EL, FH and EH) in a 4 × 4 latin square design. Higher concentrate diets resulted in lower rumen pH (P < 0.05), higher lactic acid (P < 0.001) and ammonia (P < 0.05) concentrations and lower acetate:propionate (P < 0.05). F-TMR was associated with a higher (P < 0.05) rumen volatile fatty acid concentration but no difference in other rumen fermentation characteristics compared to E-TMR. Concentrate proportion and method of feed preparation had no effect (P > 0.05) on rumen pool sizes but animals consuming the high concentrate diet had a faster (P < 0.05) rumen passage rate of NDF than animals on the low concentrate diet.