VoL 6U997): 173-IS2. Feeding value of grass ensiled with absorbents assessed in growing lambs Riitta Sormunen-Cristian Agricultural Research Centre ofFinland, Institute ofAnimal Production, FIN-31600 Jokioinen, Finland, e-mail: riitta.sormunen-cristian@mtt.fi Päivi Mannerkorpi Agricultural Research Centre ofFinland, Institute ofAnimalProduction, FIN-31600 Jokioinen, Finland, Current address: Ministry ofAgriculture and Forestry, PO Box 232, FIN-00171 Helsinki, Finland Four absorbent materials incorporated into grass at ensiling were compared in terms of their effects on silage quality, effluent production, diet digestibility, ad libitum intake and growth of lambs. The materials used (50 kg t 1 grass) to retain silage effluent flow were molassed and unmolassed sugar beet shreds (MSBS, SBS), a commercial product (CP) based on MSBS (75%) and wheat bran (20%), and rolled barley (RB). With the exception of MSBS and a control (C2), all silages were ensiled with formic acid solution. Unmolassed sugar beet shreds were also ensiled with a granulated formic acid product (grFA). The silages were fed to 56 Finnish Landrace lambs for 21 days. Silage effluent retention rates were similar (1.44-1.55 kg kg ' absorbent) for the sugar beet shred- based absorbents but zero for RB. The organic matter digestibilities of the diets were not affected (p>0.05) by the silage absorbent treatment. The digestibility of SBS silage was, however, improved by grFA as an additive. Silage intake was generally increased by absorbent inclusion, and was about 29% higher in lambs receiving silages treated with sugar beet shreds than in those receiving untreated silages. The daily growth rate of lambs was highest with the SBS treatment (124 g) followed by SBS ensiled with grFA (108 g) and MSBS (86 g); it was lowest with RB (36 g). With regard to effluent chemical oxygen demand, digestibility and silage intake, the use of SBS as an absorbent material is recommended by ensiling with either liquid or grFA. Key words: barley, chemical oxygen demand, effluent, silage, sugar beet shreds ntroduction Silage made from direct-cut grass containing less than 300 g of dry matter (DM) kg ' produces a highly polluting effluent (Gordon 1967). One of the main strategies in seeking to reduce effluent production is to incorporate absorptive materi- als into the grass at ensiling. Cereal grains are generally considered less absorptive than fibrous materials (Dexter 1961), but marked absorption has been reported under both laboratory condi- © Agricultural and Food Science in Finland Manuscript received May 1997 173 AGRICULTURAL AND FOOD SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=g3e_HTSAJp9p_DaN.jv7Zd3nzc0quBxTBGWGitw.yDJXu5r8oBNU5BPVFSxYFAKv3i_GGojLuQEML1fMHQXL7m_tyT7t6vEaMwlK5zQQjaFK7VelUTigdtueT-cOa2jJJhd79HiQOGywKVuaVJkc1ZC8xdrB7X8a3SY_wKJeJj4dWklX0hXu5kFA1eYCT9Hw8bhDejB7xAc0uZIYTwROtlgZTcqznU4A-lndQGI9MyiB-DT9yhJePZJGuO7QlDerX48kiXuYJ9_tMJChWiis1LH_PYJDLUwI9h6PZNwyzkX66-7oxbXaSMrsBM7Bx2UEfHHy8YqwAFROixB6T_dTy3QZ1Q3t Sormunen-Cristian, R. & Mannerkorpi, P. Feeding value ofgrass ensiled with absorbents tions (Spörndly 1986) and farm conditions (Done 1988, Jones et al. 1990). An ideal absorbent is expected not only to reduce effluent flow but also to have positive effects on silage feeding value and animal performance. A previous small-scale experiment identified materials which, when ensiled with grass, may reduce effluent losses (Mannerkorpi and Toivonen 1993). The purpose of the present study was to confirm these earlier findings using an ensiling technique which more closely resembles that used on a farm. Further, a common dietary energy supplement, barley, was tested as an effluent absorbent, and silage qual- ity was examined using molassed sugar beet shreds (MSBS) without the widely applied for- mic acid silage additive. The effects of various absorbent materials on silage quality, effluent production, diet digestibility and the ad libitum intake and performance of growing lambs were tested. Material and methods The absorbents were sprinkled in layers at a rate of 2.5 kg of absorbent per 50 kg of grass fresh weight (50 kg f 1 grass). The control silages (Cl and C2) were prepared without absorbents. With the exception of MSBS and the control (C2), all silages were ensiled using AIV2 solution (80% formic acid, 2% orthophosphoric acid) at a rate of 4.3 litres t 1 grass sprayed on grass during harvesting. Unmolassed sugar beet shreds were also ensiled with the same amount offormic acid in a granulated form (grFA) (Kemira Chemicals, Finland). The grFA (55% porous substance, i.e. damolin, 18% formic acid, 10%phosphoric acid) was added by hand in layers to the grass at en- siling (22.7 kg f 1). Each silo was tightly sealed with plastic after filling and weighted with con- crete blocks, 500 kg/m 2 . Silage effluentproduc- tion was measured and sampled (10%) daily for the first two weeks and thereafter weekly until the silos were opened. Effluent samples were immediately frozen. The silage retention rate was calculated as follows (in kg): (control silage cfflu ent - experimental silage cffluent )/incorporated ab- sorbent. Ensiling study Seven silages were simultaneously prepared in identical 1-tonne capacity fibreglass-walled round silos (volume 1.5 m 3, diameter 1.4 m) us- ing second-growth direct-cut timothy-fescue (50% Phleum pratense and 50% Festuca prat- ensis) grass taken on 27th and 28th August 1993 by flail harvester. The silos were fitted with in- dividual drainage systems for collecting and monitoring effluent production and composition. Samples of harvested material were collected from each load and the grass for each silo was weighed. The materials used to stem silage ef- fluent flow were molassed and unmolassed sug- ar beet shreds (MSBS, SBS), a commercial prod- uct (CP) and rolled barley (RB). The CP (a spe- cial compound feed manufactured by Suomen Rehu, Finland) was based on molassed sugarbeet shreds (75%), wheat bran (20%), malted barley (3.4%), plant oil (1.0%) and Na-benzoate (0.6%). Animal trial After a preservation period of 20 weeks, the si- los were opened and the silages removed, mixed well, sampled and vacuum-packed in smaller portions for the feeding trial and stored about for 10 days in a sheep barn (maximum tempera- ture + 15°C) before the trial started. Fifty-six Finnish Landrace lambs with an initial weight of 38 kg (SD 5.1) and an initial age of 147 days (SD 5.6) were allocated by weight and sex into seven groups in a randomised block design. The lambs were housed individually in galvanised metal cages (measuring 1.2 x 2.2 m) with three feed-bins and a water nipple. In a preliminary study, daily grass silage DM consumption (mean 58 g kg’ 1 live weight 075) was determined to es- tablish the daily portions to be fed to the ani- mals. Each group of eight lambs was offered its respective silage for 21 days. To balance the feed ration, the daily diet consisted of 200 g of soya- 174 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 6(1997): 173-182. bean meal (crude protein 512 g kg 'DM) and si- lage ad libitum to allow refusal of 10% of the silage allowance. A mineral mixture (Ca/P=l.B) and salt (NaCl) were added at 20 g and 10 g lamb 1 day 1 , respectively. The amount of silage offered and refused was recorded for each animal. Silage and feed refusal samples were collected daily during the last seven study days. Faecal samples were taken from each animal twice a day during the last five study days. Silage and faecal sam- ples were immediately frozen. Chemical analysis The DM content of the feeds, feed refusals and faecal samples was determined by oven drying at 105°C for 24h. The DM content of the silages was corrected as in Huida et al. (1986). The feed analyses of grass, silages, refusals and faeces were conducted according to standard proce- dures. In addition, the silages were analysed for total and water-soluble nitrogen by the Kjeldahl method, for ammonium nitrogen (McCullough 1967), pH and lactic acid (Barker and Summer- son 1941), for volatile fatty acid by gas chroma- tography (Huida 1973, Huida et al. 1986) and for water-soluble carbohydrates (Somogyi 1945) and ethanol (Huida 1982). The amounts of neu- tral detergent fibre (NDF) and acid detergent fi- bre (ADF) in silages were determined accord- ing to the methods of Robertson and Van Soest (1981). The digestibility coefficients for soya- bean meal were taken from the feed tables (Salo et al. 1990). The apparent digestibility of the diets was determined using acid insoluble ash as an internal marker on the last five days of the trial (Van Keulen and Young 1977). The digesti- bility of the silages was calculated by the differ- ence method (the diet - soya bean meal). The metabolisable energy (ME) of the experimental feeds was calculated according to MAFF (1975). The effluent samples were analysed for DM, crude protein by the Kjeldahl method, and wa- ter-soluble carbohydrates (Somogyi 1945). The chemical oxygen demand (COD) of the effluent was colorimetrically determined by the Hach method (Hach Company, Colorado, U.S.A.). Statistical analyses Data on organic matter (OM) digestibility, in- take of OM, intake of digestible OM and the growth rate of the lambs were analysed with the GLM procedure (SAS 1992). The model was as follows: Y... =m+A . + B+ C. + d..., where Y... isijk i j(i) k ijk’ ijk the observed response (e.g. OM digestibility), m is the overall effect, A the effect of block i (i=1..8), B.(j) the effect of animal j withinblock i (j=1..56), Ck the effect of treatment k (k=1..7) and d... the residual error. The effect oftreatments !jk was evaluated using the following contrasts: SBS + RB + CP vs. Cl, MSBS vs. C2, SBS(FA) vs. SBS(grFA) and SBS vs. CP. Results and discussion The weatherbefore ensiling was dull and show- ery but not rainy. The grass contained (with standard deviations) dry matter 157 gkg ' (11.4), crude protein 143 g kg' 1 DM (5.6), crude fibre 282 gkg ' DM (2.4), ash 93 g kg 1 DM (1.7) and water-soluble carbohydrates 102 g kg' 1 DM (8.5). The chemical composition of the absorbents is given in Table I. Silage effluent and chemical oxygen demand The results given in Table 2 indicate that none of the absorbents could totally retain the efflu- ent. The MSBS absorbent treatment without the use of formic acid additive was the most effec- tive in retaining effluent (1.58 kg kg ') followed by SBS, SBS ensiled with grFA and CP. The absorption ability of the sugar beet shreds was 175 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Sormunen-Cristian, R. & Mannerkorpi, P. Feeding value ofgrass ensiled with absorbents Table 1. Chemical composition of the absorbents used in the study. SBS RB CP MSBS DM, g kg' 1 897 881 891 883 In DM, g kg 1 Ash 39 25 69 57 Crude protein 118 148 129 125 Ether extract 4 20 20 5 Crude fibre 186 46 163 154 N-free extract 653 761 619 659 SBS = unmolassed sugar beet shreds, RB = rolled barley, CP =a commercial product based on molassed sugar beet shreds (75%) and wheat bran (20%), MSBS = molassed sugar beet shreds, DM = dry matter thus better than in the study of Kennedy and Moore (1988) (1.0 I effluent kg' 1 absorbent). Rolled barley was the most ineffective absorb- ent for controlling effluent loss; effluent flow from RB silage was twice as high as that from MSBS silage and even higher than that from the control silage. These findings differ from those of Done (1988) and Offer and Al-Rwidah (1989), who found a significant reduction in effluent production when RB was incorporated into grass at ensiling. According to Jones et al. (1990), in- corporation of RB may reduce effluent flow by up to 50%. Johnson (1992) found, however, that inclusion of 40 kg of RB had no effect on total effluent production, whereas rates of 60 kg and 80 kg showed progressively more effect on ef- fluent flow. Here the amount of RB (50 kg f 1 grass) used was, therefore, probably too low for efficient effluent retention. The use of formic acid in granulated form instead of liquid form did not affect the effluent retention rate. There were clear differences in chemical composition between the effluents produced by the different silages. The mean DM of effluent produced from silages treated with sugar beet shreds was 45 g kg 1, which is in close agree- ment with that reported by Purves and McDon- ald (1963) for farm silos (40 g I' 1). With the ex- ception of RB silage, the absorbent-treated si- lages showed lower DM losses than untreated silages. However, effluent from the treated si- lages contained more sugar and crude protein than effluent from the corresponding control because the nutrients of the absorbents were also solubilized. The use of MSBS without any acid preservative resulted in a smaller amount ofsugar in effluent than did unmolassed silage treated with formic acid. This was attributed to the hy- drolytic effect of formic acid (compare Cl with C 2), which was used in combination with the SBS treatment. The polluting strength of an effluent is de- scribed by its chemical oxygen demand (COD). The most environmentally friendly combination of absorbent and silage additive in terms of high retention rate and low COD content of effluent was SBS with grFA. The silage preserved with grFA had lower nutrient losses and COD than the silages treated with FA. Only the effluent of Cl silage had a lower COD content; this silage had, however, higher effluent production. The use of MSBS instead of SBS increased the COD of the silage effluent (MSBS 53.2 vs. SBS 43.4), which is consistent with the findings of a previ- ous small-scale experiment (Mannerkorpi and Toivonen 1992). The COD values of 33.7-53.2 (mg 1 1 x 103 ) are in agreement with those pre- sented by Jones et al. (1990). Chemical composition of silages The chemical composition and quality of silages at silo opening are given in Table 3. The aver- age DM content of the control silages during the ad libitum feeding period was 209 g kg 1 but that of the silages containing absorbents 219 g kg ’ (Table 4). Incorporation of sugar beet shreds has been found to increase the silage DM content (Offer and Al-Rwidah 1989). Silages treated with sugarbeet shreds had a lower crude protein con- tent than untreated or RB treated silages owing to the dilutive effect of the absorbents with mark- edly lower crude protein contents than in grass. Comparison of the formic acid-treated silages showed that SBS and CP inclusion raised the sugar content but that RB silage, in which etha- 176 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 6 (1997): 173-182. Table 2. Effects of absorbent inclusion and formic acid treatment on effluent quantity, composition, dry matter losses, retention rate and chemical oxygen demand. Silages Absorbent Cl SBS SBS RB CP C 2 MSBS Silage additive FA FA grFA FA FA Grass, kg 1000 875 1000 900 1000 1000 KXX) Absorbents, kg 43.8 50 45 50 50 Effluent: Amount, % of grass FM 22.4 17.3 17.7 26.1 18.0 21.0 13.1 DM, g kg 1 37 47 38 43 48 42 48 DM losses, % 5.3 4.0 3.3 5.6 4.3 5.6 3.1 Sugar, g kg 1 12 18 13 15 19 4 7 Crude protein, g kg' 7 9 8 10 9 11 13 Specific gravity 1.017 1.021 1.016 1.019 1.021 1.014 1.018 Retention rate, kg kg-' absorbent 0 1.55 1.49 -0.74 1.44 0 1.58 COD, mg l 1 x 10' 33.7 43.4 35.8 42.8 45.2 40.8 53.2 C 1 = control silage with formic acid, SBS = unmolassed sugar beet shreds, RB = rolled barley, CP =a commercial product based on molassed sugar beet shreds (75%) and wheat bran (20%), C 2 = control silage without any additives, MSBS = molassed sugar beet shreds, FA = 80% formic acid solution, grFA = granulated formic acid solution, DM = dry matter, FM = fresh matter, COD = chemical oxygen demand nol and lactic acid production were highest, had the lowest sugar content. Differences between silages in contents of crude fibre and N-free ex- tract were small. The ash content of SBS ensiled with grFA was conspicuously high. All silages were well preserved (Table 3 - 4). Only the control silage ensiled without any additive (C2) contained BO g kg ' total nitrogen. Butyric acid was encountered in small amounts in silage SBS ensiled with grFA. None of the absorbents incorporated in formic acid- treated silage (C 1) had a marked effect on silage quality with the exception of SBS in combina- tion with formic acid, which improved silage fermentation owing to the lower content. The results for RB are consistent with those of Johnson(1992) and Done (1988), who found that RB used as an absorbent did not improve fer- mentation quality in silage prepared withoutany additives. In the untreated control silage (C 2), fermentation quality as reflected by lower am- monia N/total N and acetic acid content and pH was clearly increased by MSBS inclusion. Be- cause of the more extensive lactic acid fermen- tation in silages not treated withformic acid, pH values were generally higher in silages treated with formic acid than in untreatedsilages, as was found also by Offer and Al-Rwidah (1989). Digestibility, intake and growth rate In general, diet organic matter digestibility was not affected (p>0.05) by silage absorbent treat- ment (Table 5). Digestibility of SBS silage was, however, increased when grFA was used as an additive (p=0.0003) owing to the nutrient absorp- tion capacity of the grFA product. This silage also showed the highest digestibility (80.6%). The formic acid-treated control silage (Cl) had the lowest digestibility (77.1%). In the study of Mannerkorpi and Toivonen (1993), inclusion of SBS and MSBS increased the in vitro organic matter digestibility of silages. Offer and Al- Rwidah (1989) likewise found that silage digest- ibility in vitro was improved by the addition of 177 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Sormunen-Cristian, R. & Mannerkorpi, P. Feeding value ofgrass ensiled with absorbents Table 3. Quality of silages at silo opening (C 2 sample is taken 28 days earlier) with standard deviation. In each figure pair the upper figure is the mean and the lower figure the standard deviation. Silages Absorbent Cl SBS SBS RB CP C 2 MSBS Silage additive FA FA grFA FA FA Number of samples 4 4 4 4 4 1 4 DM, g kg" 1 197 215 222 224 218 195 212 1.2 3.4 5.4 6.1 4.4 2.5 In silage DM, g kg ' WSCs 92 109 92 89 122 29 24 6.9 2.7 6.8 20.3 5.1 1.4 Lactic acid 8.6 7.8 9.2 19.2 10.3 93.2 87.2 1.3 1.4 1.4 2.9 2.2 2.5 Formic acid 12.3 10.7 18.4 10.9 11.9 0.5 0.5 4.0 1.9 3.1 2.8 0.8 0.4 Aseticacid 18.5 18.4 12.7 13.8 14.7 26.1 19.9 5.1 2.8 0.3 1.3 0.7 1.5 Butyric acid 0.3 0 0 0 0 0 0 0.3 Ethanol 10.0 6.5 9.4 19.9 5.2 11.3 25.0 1.2 1.0 1.2 0.4 0.5 1.3 Total-N 23.6 22.4 21.5 22.9 23.1 22.4 22.8 0.5 0.6 0.3 0.4 0.9 0.5 NH,-N/N 33.4 25.0 28.8 47.3 27.3 54.9 54.7 7.1 2.0 1.4 3.7 1.8 2.0 Soluble-N/N 389.1 359.7 425.9 515.8 408.7 558.4 538.8 77.9 55.7 10.9 18.5 13.5 15.4 pH 4.19 4.07 3.92 4.18 4.32 3.94 3.98 0.10 0.04 0.03 0.05 0.05 0.03 Cl =control silage with formic acid, SBS = unmolassed sugar beet shreds, RB = rolled barley, CP = a commercial product based on molassed sugar beet shreds (75%) and wheat bran (20%), C 2 = control silage without any additives, MSBS = molassed sugar beet shreds. FA = 80% formic acid solution, grFA = granulated formic acid solution. DM = dry matter, WSCs = water-soluble carbohydrates MSBS and RB. Lambs offered absorbent-treat- ed silage had significantly higher OM intakes of ensiled material than those offered untreated si- lage (SBS+RB+CP vs. Cl, p=0.004, MSBS vs. C2, p=0.0001) (Table 5). Intake of diet organic matter was about 29% higher for lambs receiv- ing silages treated with sugar beet shreds than untreated silages. This finding suggests that the increased intake for treated silages was not a result of better silage digestibility but of either palatability or the effect of absorbent treatment on rumen fermentation kinetics. In general, in- take was higher for the absorbents with the most efficient effluent retention rates. The observed positive effects of absorbents on intake are consistent with the findings of Jones et al. (1990), Johnson (1992) and Davies and Perrott (1991), but not with the observation ofKennedy (1988), who reported that intake by cattle receiving 2 kg ofsupplementary feed head' 1 day 1 was unaffected by absorbent treatment. In the study of Done and Appleton (1988), MSBS, but not RB, treatment improved the dai- ly DM intake. In our study, intake of silage treat- 178 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 6 (1997): 173-182. Table 4. Chemical composition and quality of silages in ad libitum feeding period. Silages Absorbent Cl SBS SBS RB CP C 2 MSBS Silage additive FA FA grFA FA FA Number ofsamples 1111111 DM, g kg 1 202 215 226 223 218 217 212 In silage DM, g kg ' Ash 81 83 130 80 87 99 90 Crude protein 152 149 142 158 145 147 151 Ether extract 51 44 42 49 44 54 48 N-free extract 403 429 391 433 496 428 415 Crude fibre 313 295 295 280 278 278 296 NDF 573 560 546 542 519 539 533 ADF 326 309 300 287 292 302 300 WSCs 25 88 56 8 98 13 12 lactic acid 25.3 13.0 11.1 44.0 23.4 100.7 85.1 Formic acid 10.4 9.8 11.5 2.7 7.3 0 0 Acetic acid 23.3 18.2 21.2 17.9 16.5 27.7 18.9 Butyric acid 0 0 0.4 0 0 0 0 Ethanol 25.8 21.9 25.2 44.0 13.3 10.6 26.5 Total-N 22.5 22.6 21.6 24.0 22.5 24.0 22.7 NH,-N/N 44.2 26.7 30.8 69.3 55.1 84.6 54.1 Soluble-N/N 445.9 397.1 439.4 496.3 428.6 573.1 540.1 pH 4.14 4.12 4.02 4.18 4.18 4.04 4.01 Cl = control silage with formic acid, SBS = unmolassed sugar beet shreds, RB = rolled barley, CP = a commercial product based on molassed sugar beet shreds (75%) and wheat bran (20%), C 2 = control silage without any additives, MSBS = molassed sugar beet shreds, FA = 80% formic acid solution, grFA = granulated formic acid solution, DM= dry matter, NDF = neutral detergent fibre, ADF = acid detergent fibre, WSCs = water-soluble carbohydrates ed with RB was also noticeably lower than that of silages treated with sugar beet shreds, most likely due to silage fermentation quality. Further- more, the RB silage had an unpleasant mucous consistency and a particularly sweet smell. Vol- untary feed intake can be reduced by a high lac- tic acid content of silage (McLeod et al. 1970). The high lactic acid content in MSBS silage without formic acid treatment may partly explain why intake of this silage was lower than that of other sugar beet shred-treated silages. The most palatable SBS-grFA silage included butyric acid. Experience has shown that butyric acid does not necessarily affect silage intake (Sormunen-Cris- tian 1984). The use of sugar beet shreds as absorbents improved the diet ME value (p=0.003) and live weight gains of lambs (p=0.02). Daily growth of lambs was highest with SBS silage (124 g), next highest with SBS ensiled with grFA (108 g) and lowest with RB (36 g). Incorporation of sugarbeet shreds has yielded a tendency towards higher lamb live weight gains (Done 1988), but the improvement in silage ME value has been slight (Offer and Rwidah 1988).One of the lambs in the group fed RB silage lost weight and two of them did not grow at all. All the above findings refer to an absorbent- treated grass silage compared with pure grass si- lage. If the objective is to establish whether there is a differencebetween absorbent/concentrate add- ed at ensiling and that fed separately, a different 179 AGRICULTURAL AND FOOD SCIENCE IN FINLAND 2 Sormunen-Cristian, R. & Mannerkorpi, P. Feeding value ofgrass ensiled with absorbents Table 5. Digestibility and intake of silage (grass silage with absorbent) and of diet (silage plus soya-bean meal) and growth rate of lambs in ad libitum period. Silages Contrasts Absorbent Cl SBS SBS RB CP C 2 MSBS SEM SBS+RB+CP MSBS SBS(FA) SBS Silage additive FA FA grFA FA FA - - vs. CI vs.C2 vs.SBS(grFA)vs.CP Silage: Digestibility of OM (%) 74.7 76.1 79.4 76.2 75.6 76.4 77.0 0.56 Voluntary intake of OM (gday 1) 658 798 816 710 831 518 774 31.8 (gkg'W" 75) 43 51 51 46 53 33 49 2.0 Diet: Digestibility of OM (%) 77.1 77.8 80.6 78.0 77.4 79.0 78.7 0.49 NS NS 0.0003 NS Metabolisable energy" (MJkg'DM) 10.9 11.2 11.2 11.3 11.1 11.1 11.3 0.08 0.003 0.01 NS NS Voluntary intake of OM (gday 1) 823 963 881 964 996 683 939 32.9 0.004 0.0001 NS NS (gkg-'W ~7 'i) 53 62 62 56 64 44 60 2.1 0.005 0.0001 NS NS Voluntary intake of DOM (gday 1) 634 749 791 676 771 538 737 26.0 0.002 0.0001 NS NS (gkg'W' 1") 41 48 50 44 49 35 47 1.6 0.003 0.0001 NS NS Growth rate, g lamb' day' 41 124 108 36 89 48 86 15.6 0.02 NS NS NS Cl = control silage with formic acid, SBS = unmolassed sugar beet shreds, RB = rolled barley, CP = a commercial product based on molassed sugar beet shreds (75%) and wheat bran (20%), C 2 = control silage without any additives, MSBS = molassed sugar beet shreds, FA = 80% formic acid solution, grFA = granulated formic acid solution, SEM =standard error of means, OM = organic matter, DM = dry matter, DOM = digestible organic matter, W° J! = metabolic live weight. NS = non significant type of experiment must be carried out. According to theresults of Johnson(1992), a greater increase in animal live weight gain could be expected if the same amounts ofRB were fed separately with un- treated silage rather than as an absorbent. In con- trast, Done and Appleton (1998) found no evidence of better performance in lambs fed a “complete” diet than in those offered silage and supplement as separate components. Conclusions In general, there was no difference between SBS, MSB and CP silages in the animal parameters measured. The use of grFA product did not re- duce effluentproduction but it clearly decreased effluent COD and thereby silage digestibility without affecting growth of lambs. Incorpora- tion of MSBS without formic acid treatment improved silage quality and increased intake, but did not affect lamb growth. Further, it reduced effluent production but increased its COD. Rolled barley did not retain silage effluent, nor was the silage palatable for the lambs. In view of the effects on effluent COD, digestibility and silage intake, it is recommended thatSBS be used as absorbent and grFA as silage additive. Acknowledgements. The authors wish to thank the techni- cal staff of Animal Nutrition Section of Agricultural Re- search Centre for their assistance in conducting the trial. 180 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 6 (1997): 173-182. References Barker, S.B. & Summerson, W.H. 1941. The colorimetric determination of lactic acid in biological material. Journal of Biological Chemistry 138; 53-553. Davies, O.D. & Perrott, J.G. 1991. The effects of ensiling molassed sugar beet feed with grass on dairy cow performance. Animal Production 52: 588-589. (Ab- stract). Dexter, S. 1961. Water retaining capacity of various si- lage additives and silage crops under pressure. Agronomy Journal 53: 379-381. Done, D.L. 1988. 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Journal of Animal Science 44: 282- 287. 181 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Sormunen-Cristian, R. & Mannerkorpi, P. Feeding value ofgrass ensiled with absorbents SELOSTUS Eri absorbenteilla valmistettu säilörehu karitsoiden ruokinnassa Riitta Sormunen-Cristian ja Päivi Mannerkorpi Maatalouden tutkimuskeskus Säilörehusiilojen täytön yhteydessä ruohon joukkoon lisättiin kerroksittain (50 kg/1000 kg rehua) absor- benteiksi puristeleikettä (melassoimaton leike), säi- löleikettä (75 % melassileikettä ja 20 % vehnänle- settä), litistettyä ohraa ja melassileikettä. Säilöntäai- neena käytettiin AIV 11-liuosta sekä granuloitua muu- rahaishappovalmistetta tai säilöntäainetta ei käytetty lainkaan. Puristenesteen ympäristöä kuormittavaa vaikutusta selvitettiin mittaamalla, kuinka paljon ab- sorbentit pidättivät puristenestettä sekä mikä oli pu- ristenesteen kemiallinen hapenkulutus (COD). Säilö- rehujen maittavuutta, rehuarvoa ja sulavuutta tutkit- tiin kasvavilla karitsoilla. Vapaan säilörehuruokinnan lisäksi karitsat saivat soijaa 200 g eläintä kohti päi- vässä. Koko rehuannoksen sulavuus määritettiin käyt- tämällä happoon liukenematonta tuhkaa rehun sisäi- senä merkkiaineena. Ympäristöystävällisin absorbentti-säilöntäainepa- ri saatiin rehulla, joka valmistettiin granuloidulla muurahaishapolla ja absorbenttina käytettiin puriste- leikettä. Ohra ei sitonut puristenestettä lainkaan. Ko- konaishapen kulutusta kasvattava tekijä oli selvästi absorbenttien ravinnepitoisuus ja ravinteiden liuke- neminen puristenesteen mukana. Absorbenttien käyt- täminen ei vaikuttanut rehuannoksen sulavuuteen. Parhain orgaanisen aineen sulavuus (80,8 %) oli re- hulla, joka oli valmistettu granuloidulla muurahais- hapolla ja jossa absorbenttina oli puristeleike ja huo- noin (77,3 %) AIV II:lla valmistetulla kontrollisäi- lörehulla. Karitsat söivät eniten leikkeillä valmistettuja säi- lörehuja sekä kasvoivat niillä myös parhaiten. Ko- keellisen granuloidun muurahaishappovalmisteen käyttäminen AIV 11-liuoksen sijasta ei vähentänyt puristenesteen erittymistä, mutta se vähensi huomat- tavasti puristenesteen kemiallista hapenkulutusta si- toen siis ravinteita. Melassileike paransi säilörehun laatua ja vähensi puristenesteen eritystä verrattuna painorehuun, mutta se nosti puristenesteen kemiallis- ta hapenkulutusta. Melassoimattoman puristeleikkeen käyttö absorbenttina osoittautui tuloksiltaan parhaim- maksi. 182 AGRICULTURAL AND FOOD SCIENCE IN FINLAND