Corrigendum to Irish Journal of Agricultural and Food Research, Volume 51, Number 1, 2012, pages 79–84. Available at http://hdl.handle.net/11019/324Corrigendu

King, Colman

McEniry, Joseph

O'Kiely, Padraig

Irish Journal of Agricultural and Food Research

English

T-Stór

79Irish Journal of Agricultural and Food Research 51: 79–84, 2012†Corresponding author: padraig.okiely@teagasc.ie A note on the fermentation characteristics of red clover silage in response to advancing stage of maturity in the primary growthC. King, J. McEniry and P. O’Kiely†Teagasc, Animal and Grassland Research & Innovation Centre, Grange, Dunsany, Co. Meath, IrelandThis study investigated the silage fermentation characteristics of red clover (Trifolium pratense L., var. Merviot) harvested at five dates in the primary growth (at two week intervals from 12 May to 7 July). Despite the challenging herbage ensilability charac-teristics pre-ensiling [i.e. low dry matter (DM) concentration (142 to 178 g/kg), low water soluble carbohydrate concentration (51 to 118 g/kg DM) and high buffering capacity (552 to 639 mEq/kg DM], the silages preserved successfully and showed little evidence of clostridial activity (i.e. low concentration of butyric acid and ammonia-N). Stage of maturity at harvest had little effect on silage fermentation characteristics.Keywords: aerobic stability; dry matter recovery; harvest dateIntroductionThe chemical composition of a crop at harvest can have a major impact on silage fermentation characteristics and the over-all success of the ensilage process (Buxton 1996). In general, red clover has a lower water soluble carbohydrate (WSC) con-centration and a higher buffering capacity (BC) than most common grass species, making it more difficult to preserve as silage (Buxton and O’Kiely 2003).  Furthermore, herbage harvested at an early vegetative rather than a later more reproductive stage of maturity generally has a lower dry matter (DM) concentration and a higher BC (King et al. 2012a). Consequently, this herbage would also be expected to be more difficult to preserve. The objective of this study was to investigate the effect of stage of maturity in the primary growth on the silage fermentation characteristics of red clover.80     IRISH JOURNAL OF AGRICULTURAL AND FOOD RESEARCH, VOL. 51, NO. 1, 2012Materials and MethodsHarvesting and ensilingRed clover (var. Merviot) was grown in field plots (20 m2; 25 kg seed sown per ha in 2008) in three replicate blocks at Grange (53°30′N, 6°40′W). Within each block, five red clover plots were harvested on one of five dates (two-week intervals from 12 May – 7 July; Harvests 1 to 5) in the primary growth during 2009, as described by King et al. (2012a). Briefly, at each harvest date the unwilted herbage was harvested using a Haldrup forage plot harvester (J. Haldrup, Løgstor, Denmark), passed through a precision-chop harvest-er (MEX V1, Pottinger, Grieskirchen, Austria; nominal chop-length of 19 mm) and a representative 6 kg sample from each plot was ensiled in a separate labo-ratory pipe silo (n=3 silos per harvest; O’Kiely and Wilson 1991) for 100 days. A 10.5 kg steel weight was added to each silo to compress the herbage. Silage effluent (if any) was stored in a separate space at the bottom of the silo, and was removed and weighed prior to opening the silo. A representative 2 kg sample of each herb-age pre- and post-ensiling was stored at -18°C prior to chemical analyses. Prior to harvesting, the phenological growth stage was determined for 20 randomly sampled plants from each plot, according to the system of Ohlsson and Wedin (1989).Chemical analysis Representative herbage samples pre- and post-ensiling were dried at 98 °C and 85 °C, respectively, for 16 h in an oven with forced air circulation to estimate DM concentration and silage samples were corrected for the loss of volatiles by the equation of Porter and Murray (2001). Herbage chemical composition pre- and post- ensiling were determined as described previously by King et al. (2012a) and McEniry et al. (2006), respectively.    Aerobic stabilityAfter each of the silages had been sampled on day 100, the remainder of the silage from each laboratory silo was used to assess aerobic stability and deterioration as described by O’Kiely and Marron (2003). The main indices of aerobic stability and deterioration were the interval in hours until the temperature increased more than 2 °C above the mean (s.d.) reference tem-perature [19.6 (0.75) °C] and the accumu-lated average daily temperature rise (°C) up to 120 h of aerobiosis, respectively.Statistical analysisThe changes in herbage chemical com-position as a result of ensiling were cal-culated by subtracting values for herbage pre-ensiling from herbage post-ensiling. These data, together with data on herbage chemical composition pre-ensiling, silage fermentation characteristics, effluent pro-duction, DM recovery and aerobic stability and deterioration indices were analysed as a randomised complete block design (with triplicate blocking being accounted for) using the MIXED procedure of SAS (SAS 2004). Although it had been anticipated that three replicate blocks would be adequate for this study, the scale of within treatment variation recorded indicated that triplicate replication was insufficient to provide sensi-tive contrasts of treatments. Consequently the effects of harvest date were separated into linear and quadratic effects, and the trends due to harvest date were elucidated. However, for fermentation variables where no linear effect occurred and the quadratic trends were difficult to interpret, the Tukey test was used to compare pairs from indi-vidual harvest dates.Results Table 1 shows phenological growth stages, chemical composition pre-ensiling and  KING ET AL.: FERMENTATION CHARACTERISTICS OF RED CLOVER SILAGE 81Table 1. Herbage chemical composition [g/kg dry matter (DM), unless indicated otherwise] pre-ensiling (Pre-E) and changes in chemical composition as a result of ensiling (i.e. herbage post-ensiling – herbage pre-ensiling; a negative value indicates a decrease during ensiling) for red clover harvested at five dates (at two-week intervals from 12 May–7 July; Harvests 1–5, respectively) in the primary growthHarvestGrowth stage1Chemical composition2DM (g/kg)DMD (g/kg)NDFADFCPWSCBC (mEq/kg DM)Pre-EChangePre-EChangePre-EChangePre-EChangePre-EChangePre-EChangePre-E13.114225812-5338718220501957118-11263923.714812717-49471122855315111101-6655234.51789686-3643245276491601282-8058345.71769635-374292630724158657-6755957.415810611-3346640308551591551-52571Standard error of the mean6.74.829.833.716.015.418.215.910.26.54.711.618.2Significance***********Linear effect **********Quadratic effect**1 Growth stage: 3=early bud, 4=late bud, 5=early flower, 7=early seed pod (Ohlsson and Wedin 1989).2  DMD=dry matter digestibility, NDF=neutral detergent fibre, ADF=acid detergent fibre, CP=crude protein, WSC=water soluble carbohydrates, BC=buffering capacity.82     IRISH JOURNAL OF AGRICULTURAL AND FOOD RESEARCH, VOL. 51, NO. 1, 2012changes in chemical composition as a result of ensilage. In general, for the herb-age pre-ensiling advancing harvest date had a quadratic effect (P<0.01) on DM concentration (i.e. increase to Harvest 3 and 4; Table 1). In addition, there was a linear decrease in dry matter digestibil-ity (DMD; P<0.001), WSC concentration (P<0.001) and BC (P<0.05) and a lin-ear increase in herbage neutral detergent fibre (NDF; P<0.05) and acid detergent fibre (ADF; P<0.01) concentration with advancing harvest date.Ensiling resulted in a numerical increase in herbage DM, NDF, ADF and crude protein concentrations and a numerical decrease in DMD, and these changes did not differ (P>0.05) across the five harvest dates (Table 1). In contrast, the decrease in WSC concentration during ensiling was greatest (P<0.05) for the early (Harvest 1) compared with the later harvest dates. On average, silage pH and concentra-tions of acetic acid, propionic acid and ethanol were higher (P<0.05) and lac-tic acid (LA; P<0.01) concentration and LA as a proportion of total fermentation products (P<0.001) were lower for the Harvest 2 and 5 silages compared to the silage made at the other harvest dates (Table 2). Harvest date did not affect (P>0.05) butyric acid (BA) or ammonia-N concentrations.  Harvest date had no significant effect (P>0.05) on silage DM recovery or any of the indices of aerobic stability or dete-rioration measured (Table 2). There was a linear decrease (P<0.001) in effluent pro-duction with advancing harvest date.  Discussion The low DM concentration of the red clo-ver pre-ensiling (142–178 g/kg) resulted in the production of large volumes of efflu-ent (104–239 g effluent per kg of fresh crop ensiled) during ensilage and this was particularly evident at the first two harvest dates. This was further reflected in the low DM recovery rates of these silages (0.79 and 0.81 g/kg ensiled for the Harvest 1 and 2 silages, respectively). Ensiling also resulted in a decrease (42 g/kg, on aver-age) in DMD reflecting both soluble nutri-ent losses in the effluent and the increase in NDF and ADF concentrations. The greater increase in ADF than NDF con-centration during ensiling was indicative of a decrease in the hemicellulose fraction, and this may have provided additional substrate for fermentation (McDonald, Henderson and Heron 1991). The relatively low WSC concentration and high BC of the red clover pre-ensiling would be expected to present a chal-lenge to preservation (Buxton and O’Kiely 2003) as it has done with grass (King et al. 2012b). This was further reflected in fermentation coefficient (fermentation coefficient=DM (g/100 g)+8 WSC/BC) values of 24, 24, 25, 23, 20 for Harvests 1 to 5, respectively, which are lower than the critical value of 45 considered to be essential for production of anaerobically stable silage free of BA (Weissbach 1996). However, despite these low fermenta-tion coefficients, the red clover herbag-es in this study exhibited relatively little clostridial activity as evidenced by BA and ammonia-N concentrations of <10 g/kg DM and 100 g/kg N, respectively. This would be considered a satisfactory preser-vation according to the criteria of Haigh and Parker (1985). The higher concentra-tion of silage fermentation products than of pre-ensilage WSC (by a mean factor of 1.25 to 2.73 across harvests) suggests that additional fermentable substrate became available during ensilage.The majority of these herbages (Harvests 1, 3 and 4) underwent a lactic acid dominant fermentation (>0.70 LA as a proportion  KING ET AL.: FERMENTATION CHARACTERISTICS OF RED CLOVER SILAGE 83Table 2. Silage fermentation characteristics [g/kg dry matter (DM), unless indicated otherwise and excluding pH], silage DM recovery (DMR; g/kg), effluent production (g effluent/kg fresh herbage ensiled) and indices of aerobic stability and deterioration for red clover harvested at five dates (at two-week intervals from 12 May–7 July; Harvests 1–5, respectively) in the primary growthHarvestSilage fermentation characteristics1DMR2EffluentAerobic stability3 pHLAAAPABAEthanolNH3-N(g/kg N)FPLA/FP(g/g)Time to temperature rise >2 °C (h)ACT 120 h (°C)14.15112222.51.116611540.720.792391172.424.3943465.70.031611260.350.812311144.933.9286200.50.011471180.730.951081520.643.8882210.70.07461110.750.931041153.954.5835546.43.340691390.270.891421621.3Standard error of the mean0.13811.67.11.441.565.710.514.10.0620.04822.135.21.94Significance***********Linear effect ***Quadratic effect****1  LA=lactic acid, AA=acetic acid, PA=propionic acid, BA=butyric acid, NH3-N=ammonia-N, FP=total fermentation products (LA + AA + PA+ BA + ethanol), LA/FP=lactic acid as a proportion of total fermentation products.2 Silage DM recovery was calculated as the proportion of silage DM weight removed from the laboratory silos relative to herbage DM weight ensiled.3  ACT 120=accumulated temperature rise up to 120 h of aerobiosis. 84     IRISH JOURNAL OF AGRICULTURAL AND FOOD RESEARCH, VOL. 51, NO. 1, 2012of total fermentation products). However, the Harvest 2 and 5 herbages underwent a more hetero-fermentative fermentation and consequently had a higher pH. The reason for this difference in silage fer-mentation characteristics between harvest dates is unclear, but may reflect temporal variation in the epiphytic microbial com-munity (McDonald et al. 1991). In conclusion, despite the herbage chemical composition pre-ensiling being indicative of a challenge to preservation [i.e. low DM concentration (142–178 g/kg), low WSC concentration (51–118 g/kg DM) and high BC (552 to 639 mEq/kg DM], stage of maturity at harvest had little effect on silage fermentation characteris-tics and all red clover silages in this study preserved successfully and showed little evidence of clostridial activity.AcknowledgmentsThe authors thank B. Weldon, Grange farm staff and the staff of Grange Laboratories. Funding was provided under the National Development Plan, through the Research Stimulus Fund (#RSF 07 557), administered by the Department of Agriculture, Food & the Marine, Ireland. References Buxton, D.R. 1996. Quality-related characteristics of forages as influenced by plant environment and agronomic factors. Animal Feed Science and Technology 59: 37–49.Buxton, D.R. and O’Kiely, P. 2003. Preharvest plant factors affecting ensiling. In: “Silage Science and Technology”, (eds. D.R. Buxton, R.E. Muck and J.H. Harrison), American Society of Agronomy, Madison, WI, USA, pages 199–250.Haigh, P.M. and Parker, J.W.G. 1985. Effect of silage additives and wilting on silage fermenta-tion, digestibility and intake, and on liveweight change of young cattle. Grass and Forage Science 40: 429–436.King, C., McEniry, J., Richardson, M. and O’Kiely, P. 2012a. Yield and chemical composition of five common grassland species in response to nitrogen fertilizer application and phenological growth stage. Acta Agriculturæ Scandinavica, Section B - Soil & Plant Science 62: 644–658.King, C., McEniry, J., Richardson, M. and O’Kiely, P. 2012b. Silage fermentation characteristics of grass species grown under two nitrogen fertilizer inputs and harvested at advancing maturity in the spring growth. Grassland Science, in press.McDonald, P., Henderson, A.R. and Heron, S.J.E. 1991. “The Biochemistry of Silage”, Second Edition, Chalcombe Publications, Marlow, England, 226 pages.McEniry, J., O’Kiely, P., Clipson, N.J.W., Forristal, P.D. and Doyle, E.M. 2006. The microbiological and chemical composition of baled and precision-chop silages on a sample of farms in County Meath. Irish Journal of Agricultural and Food Research 45: 73–83.Ohlsson, C. and Wedin, W.F. 1989. Phenological staging schemes for predicting red clover quality. Crop Science 29: 416–420.O’Kiely, P. and Wilson, R.K. 1991. Comparison of three silo types used to study in-silo processes. Irish Journal of Agricultural Research 30: 53–60.O’Kiely, P. Marron, J. 2003. Automation of silage aerobic stability assessment. Teagasc Beef Production Research Report (2003), Teagasc, Grange, Co. Meath, Ireland.Porter, M.G. and Murray, R.S. 2001. The volatility of components of grass silage on oven drying and the inter-relationship between dry-matter content estimated by different analytical methods. Grass and Forage Science 56: 405–411.SAS. 2004. Version 9.1.2, SAS Institute Inc., Cary, NC, USA.Weissbach, F. 1996. New developments in crop con-servation. Proceedings of the XI International Silage Conference, 8-11 September 1996, Aberystwyth, UK, pages 11–25.Received 12 October 2012

A note on the fermentation characteristics of red clover silage in response to advancing stage of maturity in the primary growth Corrigendum

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