The digestion by cattle of grass silages made with no additive or with the application of formic acid or formic acid and formaldehyde

The aim of the experiment was to assess the effect of applying, at commercially recommended rates, formic acid or formic acid/formaldehyde at ensilage upon the subsequent digestion of the silages by cattle. Three wilted grass silages were made from perennial ryegrass ensiled at a DM concentration of 206 g kg⁻¹ after a poor wilting period of 49 h without additive application and with application of 2.5 litres t⁻¹ of formic acid or of 4.5 litres t⁻¹ of a mixture of (gkg⁻¹) 500 formic acid, 200 sulphuric acid and 200 formatin giving an application rate of 15 g formaldehyde kg⁻¹ herbage crude protein (N × 6.25).
The silages were fed to cattle equipped with rumen cannulae and duodenal re-entrant cannulae. Results from analyses of silage composition and from the digestion of organic matter and N showed no major differences between silages. The efficiency of rumen microbial N synthesis, the rumen degradability of silage N (determined in vivo or in sacco ) and in vivo digestion of individual amino acids were also unaffected by additive treatment. These results indicate that poor wilting conditions before ensilage restricted the effectiveness of additive treatment; the ineffectiveness of formaldehyde in reducing the rumen degradability of silage N may also have been related to the low rate of formaldehyde application.     

Comparison of the fermentation quality and nutritive value of sulphuric and formic acid-treated silages fed to beef cattle

Five experiments were carried out in the years 1980-1983 and 1986 to study the effect of treating grass at ensiling with sulphuric acid (850 g kg^?1) and formic acid (850 g kg^?1) additives alone, and in mixtures with or without formalin on the preservation of grass, in vivo digestibility in sheep, in-silo loss, intake and performance of finishing cattle. Primary growth grass was ensiled in experiments 1 (3–4 June 1980), 2 (12-15 June 1981) and 3 (31 May-2 June 1982), primary regrowth grass in experiment 4 (1-2 August 1983) and secondary regrowth grass in experiment 5 (7-10 October 1986). During the ensiling period within each experiment, approximately 60 t of unwilted, double-chopped, additive-treated or untreated grass was packed into covered concrete-walled 60-t capacity silos. The dry matter (DM) contents of the ensiled grass in experiments 1, 2 and 5 ranged from 155-180 g kg^?1 and were lower than those recorded in experiments 3 and 4 (214 g kg^?1). With the exception of grass ensiled in experiment 2, where water-soluble carbohydrate (WSC) contents were low, at 104 g kg^?1 DM, grass in all other experiments contained relatively high WSC contents ranging from 140-154 g kg^?1 DM. In experiments 1, 3 and 4 all silages were well-preserved. However, in experiment 2 the 450 g kg^?1 sulphuric acid-treated and formic acid-treated silages displayed significantly lower pH, buffering capacity (Bc) and ammonia nitrogen contents than the untreated silage. In experiment 5, the sulphuric acid-treated and formic acid-treated silages displayed significantly lower pH, Bc, ammonia nitrogen, butyrate and volatile fatty acid (VFA) contents than the untreated silage. Each of the silages was offered daily with various levels of a supplementary concentrate for approximately 70-d periods to twelve animals of mixed breed in experiments 1, 3, 4 and 5 and to fifteen animals in experiment 2. All animals weighed between 380-470 kg at the start of the experiments. In experiments 1, 2 and 3 there were no significant differences between silages for any of the intake or animal performance parameters. In experiment 4, cattle fed the formic acid-treated silage displayed significantly higher silage DM intakes and daily liveweight gains than those fed the sulphuric acid-treated and untreated silages; in experiment 5, cattle fed the formic acid-treated silage displayed significantly higher silage DM intakes than those fed the untreated silage. It was concluded that formic acid was a more effective silage additive than sulphuric acid. Increasing the level of supplementation significantly decreased silage DM intakes in cattle in experiments 3 and 4, and significantly increased daily liveweight gains and daily carcass in cattle in experiments 1, 3 and 4.     

Re‐ensiling and inoculant application with Lactobacillus plantarum and Propionibacterium acidipropionici on sorghum silages

Re‐ensiling of previously ensiled forage has been a common practice in Brazil, and the use of inoculants may provide a means of reducing dry‐matter (DM) loss. This study aimed to determine the effect of re‐ensiling and the use of microbial inoculants on the quality of sorghum silage. Treatments were presence/absence of an inoculant (Lactobacillus plantarum and Propionibacterium acidipropionici) in the silage, and the re‐ensiling, or not, of the material after 24 h of exposure to air, and these were tested in a factorial 2 × 2 design. Losses due to gas, effluent and total DM were assessed, as were the fermentation characteristics, chemical composition, aerobic stability, and aerobic counts of microorganisms. Effluent loss was higher in re‐ensiled silage, and these silages had lower lactic acid content and higher levels of acetic and propionic acids. The in vitro DM digestibility was lower in the re‐ensiled sorghum silages. The re‐ensiled silage had higher aerobic stability. The inoculant only increased the acetic acid content of the silage. The re‐ensiling of sorghum silage increased effluent loss by 71·2%, and reduced DM digestibility by 5·35%. The use of inoculant did not influence the quality of sorghum silage.     

Effects of extended wilting, shading and chemical additives on the fatty acids in laboratory grass silages

This work investigated the range of fatty acid concentrations in grass silages made from the regrowth of perennial ryegrass Lolium perenne using different techniques involving combinations of shading of the crop before cutting, wilting and the use of chemical additives. The effects of the different silage additives on overall fermentation were large, with many of the formic acid and formalin-treated silages having a very restricted fermentation. Nonetheless, effects on levels and proportions of fatty acids were numerically small. The major differences between silages were generated during field operations (shading and wilting), with little further changes in fatty acids within the silage clamp. The extended wilt had the most dramatic effect on fatty acids with a marked reduction in both total fatty acids (24·6 vs. 17·5 g kg⁻¹ dry matter; s.e.d. = 0·65, P  < 0·001) as well as in the proportion of total fatty acids as α-linolenic acid (C18:3 n -3; 0·55 vs. 0·48; s.e.d. = 0·013, P  < 0·01). Shading the grass with a black plastic sheet for 24 h before cutting had a similar effect.     

Effects of treating lucerne with an inoculum of lactic acid bacteria or formic acid upon chemical changes during fermentation, and upon the nutritive value of the silage for lambs

A second cut of lucerne was wilted to 500 g DM kg⁻¹ and either left untreated (control) or treated with formic acid (4.5 1 fresh forage t⁻¹) or with a commercial inoculum of lactic acid bacteria (10⁵ colony forming units (cfu) g forage⁻¹). The forages were ensiled in 2-t capacity silos for 8 months, and later fed to six lambs (mean initial weight 27.7 ±1.60 kg) in a 3x3 duplicated Latin square with 27-d periods. Portions of the untreated and additive-treated forages were also ensiled in laboratory silos at 25 ° C for intervals up to 42 d. Results from the laboratory silos showed that the major increase in ammonia-N in silage occurred between 40 h and 7 d of fermentation; during this period, both formic acid and the inoculant produced a smaller increase in ammonia-N, than did the control. The pH of inoculated silage declined from 5.74 to 4.57 in 7 d, but it took 14 d for the pH of the control silage to fall below 5.0. Formic acid treatment immediately reduced the silage pH from 5.74 to 5.10 ( P < 0·01); the pH then remained unchanged until 21 d, after which it decreased slightly. When compared with control, lambs fed formic acid-treated silage consumed more ( P < 0·05) digestible organic matter; the response was associated with a trend towards decreased concentration of ammonia in plasma. Inoculation of lucerne silage did not ( P < 0·05) affect voluntary intake but increased ( P <0.05) apparent digestibility of fibre and tended to increase N retention.     

Silage and milk production: studies with molasses and formic acid as additives for grass silage

In two separate feeding experiments using a total of twenty-four individually housed Ayrshire cows six silages made from perennial ryegrass were offered ad libitum with supplements of concentrates. In Experiment I herbage with a dry matter (DM) concentration of 225 g kg⁻¹ received either formic acid ('Add-F') at the rate of 2·0 litres t⁻¹ or undiluted cane molasses at rates of 10, 20 and 30 litres t^−l; the mean daily silage intakes were 9·54, 908, 9·27 and 9·49 kg DM per cow and the daily milk yields, corrected to 40 g fat kg⁻¹, were 23·2, 22·3, 22·8 and 22·9 kg per cow respectively but none of the differences between the four treatments was significant. In Experiment 2 herbage with a DM concentration of 269 g kg⁻¹ received formic acid at a uniform rate of 2·6 litres t⁻¹ either with or without an additional application of molasses at 20 litres t⁻¹; the mean daily silage DM intakes were 8·70 and 9·28 kg per cow and the daily fat-corrected milk yields were 22·2 and 21·9 kg per cow respectively and were not significantly different. In both experiments the effects of the treatments on milk composition were small and not significant. It is concluded that there were no advantages in applying molasses to herbage treated with formic acid, and that the rate of application of molasses to untreated herbage which equated with the formic acid application was 20·30 litres t^−l when assessed on the basis of silage composition, intake and milk production.     

An evaluation of three bacterial inoculants and formic acid as additives for first harvest grass

An experiment was carried out during 1984 to study the effect of treating grass at ensiling with three commercially available inoculant-type additives (H/M Inoculant, Grass Sile and Siron), formic acid (850 g kg⁻¹; Add-F) or no additive on grass preservation, in-silo loss, intake and animal performance. Primary growth grass ensiled from 28–29 May into concrete-walled covered silos was of high dry matter (DM, 234 g kg⁻¹), water-soluble carbohydrate content (WSC. 212 g kg DM⁻¹) and digestibility (MADF, 250 g kg DM⁻¹).
The untreated silage displayed good preservation and with the exception of the Sirontreated silage which showed significantly lower buffering capacity (Be) and volatile fatty acid (VFA) contents than the untreated silage, the application of inoculant-type additives did not improve silage preservation or decrease in-silo DM losses. The formic acid-treated silage displayed significantly lower Be, water-soluble carbohydrate, ash, ammonia nitrogen (g kg total N⁻¹) and lactate contents than the untreated silage.
After a 133 d storage period, silages were offered to finishing beef cattle for an 84-d period. Cattle offered the silages displayed similar and non-significant daily DM intakes, daily liveweight gains, dressing proportions and daily carcass gains. From this experiment it appears unlikely that any of the additives evaluated will improve animal performance relative to a well-preserved untreated silage.     

Effect of anhydrous ammonia treatment on the chemical composition and nutritive value of grass hay and on intake and performance in beef steers

Two compositionally similar, mature grass hays, of dry matter contents 699 and 836 g kg^-1, were treated with anhydrous ammonia at levels of 10, 20 and 30 kg NH₃ t DM^-1 and 20, 30 and 40 kg NH₃1 DM^-1, respectively. Treatment at 10 kg t^-1 did not inhibit moulding of the damp hay. The remaining treatments increased the nitrogen contents of damp and dry hay, respectively, from 12.5 and 13.8 g kg DM^-1 to maxima of 250 and 270 g kg DM^-1 and the water-soluble ammonia-nitrogen contents of oven-dried samples from 24 and 23 g kg^-1 to maxima of 118 and 88 g kg^-1 of total nitrogen. While all treated hays had reduced levels of insoluble hemicellulose, ammoniation increased the insoluble cellulose content of damp hay only. In trials of 37 and 80 days duration, respectively, the untreated and 20 and 30 kg t^-1‘damp'-ammoniated hays and the untreated and 20, 30 and 40 kg t^-1‘dry'-ammoniated hays were offered ad libitum, unsupplemented or supplemented with 2 kg d^-1 of a barley-soya compound, to steers of 328 kg and 383 kg mean initial liveweight. Steers offered untreated and 20 and 30 kg t^-1 ammoniated damp hays and untreated and 20, 30 and 40 kg t^-1 ammoniated dry hays, all ad libitum and alone, consumed 5.50, 6.48 and 6.59 and 6.78, 782, 790 and 8.26 kg d^-1 and gained 471,560 and 521 g d^-1 and 490,699,794 and 572 g d^-1, respectively. When supplemented, the same hays, again offered ad libitum, produced live-weight gains of 529, 515 and 736 g d^-1 and 725, 705,726 and 895 g d^-1, respectively. The apparent in vivo digestibilities of hay dry matter, organic matter, gross energy, hemiceliulose, cellulose and nitrogen were significantly increased by ammoniation.     

The effect of nitrogen fertilization on the amino acid composition and nutritive value of cereals

A range of samples embracing 14 varieties from different localities within the United Kingdom, many grown with the application of different known levels of nitrogenous fertilizer, were submitted to proximate analysis, some analysed for total amino acid composition and some evaluated nutritionally in near-practical dietary mixtures with various protein concentrates.Location of growth was found to be more important than level of nitrogen application in determining the protein content of the harvested grain. Small differences in amino acid composition were noted, and there appeared to be a progressive decline in lysine content with increasing nitrogen level in the seed.Significant differences in nutritive value between the barleys were detectable in mixtures of each with protein concentrates, and in general discrimination between them was better if the accompanying concentrate was of poor quality e.g. groundnut. With fish meal differences between the barleys were well marked. The differences found were real and reproducible, and the results indicated that particular barleys differed in their ability to complement soya bean or groundnut.

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Zusammenfassung Es wurden Proben von 14 Getreidesorten untersucht, von verschiedenen Standorten Großbritanniens, die zumeist mit verschieden hohen Stickstoffgaben gedüngt waren. Die Untersuchung der Proben bezog sich teils auf die Gesamt-Aminosäuren und teils auf den ernährungsphysiologischen Wert der Proben in praxisnahen Diät-Mischungen mit verschiedenen Protein-Konzentraten.Der Protein-Gehalt des geernteten Getreides ist stärker vom Standort abhängig als von der Höhe der Stickstoffdüngung. Es wurden geringe Unterschiede in der Aminosäuren-Zusammensetzung festgestellt, und es scheint, daß bei fortschreitender Zunahme des Stickstoffgehaltes in den Getreidekörnern der Lysingehalt abnimmt.Signifikante Unterschiede im ernährungsphysiologischen Wert verschiedener Gerstensorten waren in Mischungen jeder einzelnen mit Proteinkonzentraten nachweisbar, wobei die Unterschiede im allgemeinen deutlicher wurden, wenn die zugemischten Konzentrate von geringerer Qualität waren, z.B. Erdnuß. Mit Fischmehl versetzt traten die Unterschiede zwischen den Gerstensorten weniger deutlich hervor. Die gefundenen Werte waren reproduzierbar, und die Ergebnisse weisen darauf hin, daß insbesondere die Gerstensorten, in ihrem Ergänzungswert für Sojabohne oder Erdnuß differieren.

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Résumé 14 lots de céréales, provenant de diverses stations de Grande Bretagne, et soumis à des taux différents de fumures azotées, ont été étudiés. Chaque lot était analysé au point de vue du taux d'aminoacides, et au point de vue nutritionnel, dans des mélanges analogues à ceux de la pratique, à des taux protéiques variés.Le taux de protéines d'une céréale dépend davantage de la station, que du taux de fumure. De faibles différences dans les taux d'aminoacides ont été observés; il semble que le taux de lysine décroisse lorsque croit le taux d'azote du grain.Des différences significatives dans la valeur nutritionnelle de diverses variétés d'orges apparurent, dans des mélanges de ces variétés avec des concentrés de protéines, ces différences étaient plus nettes avec des concentrés de plus médiocre qualité, par exemple formé de tourteau d'arachide. Les formés de poison ne furent pas apparaitre aussi nettement les différences parmi diverses qualité d'orges. Les résultats sont bien reproductibles, la conclusion en est que les variétés d'orges n'ont pas toute la même valeur comme supplément du tourteau de soya ou d'arachide.

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Paper presented at the conference of the International Association for Quality Research on Food Plants (CIQ) held in common with the Deutsche Gesellschaft für Qualitätsforschung (Pflanzliche Nahrungsmittel) e.V. (DGQ) in Berlin on 6th October 1972.     

Effect of harvest date on the chemical composition and nutritive value of Cerastium holosteoides

Abstract Cerastium holosteoides is a short‐lived plant often found in small proportions on dry and mesotropic semi‐natural, species‐rich grassland communities. To obtain more information about its nutritive value, two experiments on Arrhenatheretum elatioris grassland were carried out to examine the effect of harvest date on in vitro organic matter digestibility (IVOMD), neutral‐detergent fibre (NDF), acid‐detergent fibre (ADF), acid‐detergent lignin (ADL), estimated net energy for lactation (NEL) and crude protein (CP) concentrations of C. holosteoides, and selection of this plant by dairy cows grazing on semi‐natural grassland. C. holosteoides starts flowering in spring and continuously develops new flowers on new branches throughout the summer. Harvests were made in relation to particular growth stages of Dactylis glomerata present in the sward: (A) tillering; (B) stem elongation; (C) ear emergence; (D) flowering; and (E) ripening. Chemical composition and nutritive value were evaluated in 1998 and 1999. With advancing maturity, IVOMD of C. holosteoides decreased from 0·771 at growth stage A to 0·485 at growth stage E. At the same time, CP concentration decreased from 153 to 69 g kg^?1 dry matter (DM) and estimated NEL concentration from 6·00 to 4·07 MJ kg^?1 DM. With advancing maturity, there was a significant increase in NDF, ADF and ADL concentrations. In the summer harvest season, C. holosteoides contained significantly higher NDF, ADF and ADL concentrations, lower NEL concentration and had a lower IVOMD value than in the spring. Differences between years were also found for IVOMD and for NDF, ADF, ADL and NEL concentrations. In a grazing experiment in the year 1999, at growth stage B, Simmental cows grazed an A. elatioris sward in which the main species was D. glomerata (0·092), and the proportion of C. holosteoides was 0·034. C. holosteoides was, on average, grazed by cows to the same relative extent as other species in the sward.     

The effect upon fermentation and nutritive value of silages produced after treatment by three different inoculants of lactic acid bacteria applied alone or in combination

Silages were made from the first cut of a predominantly perennial ryegrass sward. The silages were either untreated (W) or treated with formic acid (31 t⁻¹, F) or with 10⁶ lactic acid bacteria (LAB) g⁻¹ grass of each of three strains alone (A. Lactobacillus plantarum MTD1; B, Pediococcus species 6A2; C, L. plantarum 6A6) or in combination (AB. AC) to give seven treatments. The silage fermentation in 10-kg silos was followed chemically and microbiologically and the nutritive value of selected treatments evaluated using 2-t silos.
The control silage (W) fermented well. Addition of formic acid restricted fermentation and produced a silage with a high ethanol concentration. After day 4, all inoculated silages had lower pH values and higher lactic acid concentrations and a higher ratio of lactic acid to acetic acid than the control silage. Chemically there was little difference between the inoculated silages in terms of final composition. Microbiologically the LAB applied in treatments B and C dominated the LAB populations in those silages when applied alone; however, they were suppressed when applied in combination with inoculant A.
When fed to sheep, the intake of the formic acid-treated silage was significantly ( P < 0·01) lower than that of the other silages and the intake of silage treated with inoculant A significantly ( P < 0·001) higher than that of silages treated with inoculants B and C. The apparent organic matter ( P < 0·001) and nitrogen ( P < 0·01) digestibilities of the formic acid-treated silage were also significantly lower than those of the other silages.     

Inclusion of alfalfa improves nutritive value and in vitro digestibility of various straw–grass mixed silages in Tibet

To enlarge the feed resources and enhance the utilization efficiency of straws as ruminant feed in Tibet, four kinds of local crop straws with tall fescue (Festuca arundinacea Schreb.) based on the ratio of 40/60 (fresh weight) were ensiled with four levels (0, 10%, 20% and 30% of fresh weight) of alfalfa (Medicago sativa L.), respectively. The laboratory silos (1L) were opened after 45 days of ensiling, and the fermentation characteristics, nutritive value and in vitro digestibility of the mixed silages were analysed. The silages including alfalfa had significantly (p < 0.05) or numerically (p > 0.05) higher lactic acid and crude protein contents, lactic acid bacteria counts, in vitro digestibility of dry matter, neutral detergent fibre (NDF) and acid detergent fibre (ADF), and lower NDF and ADF contents than controls. The results suggest that inclusion of alfalfa to mixtures of straws and tall fescue had favourable effects on fermentation quality and obviously improved the nutritive value and in vitro digestibility of mixed silages. This effect was most evident when the inclusion proportion of alfalfa was 30% in oat straw mixed silage.     

The effect of urea on the voluntary intake by calves of silages preserved with formaldehyde and formic acid

Perennial ryegrass cv. S23 was preserved by fermentation (C), or with the addition of 8.7 1 formalin (35% w/w formaldehyde) per t fresh herbage (F) or of 9.0 1 equal mixture (by vol.) of formalin and formic acid (85% w/w solution) per t fresh herbage (FF). These three silages comprised the treatments in a three-period, crossover design in which urea (u) was given at the rate of 20 g per kg dietary DM to half the animals. Twelve calves were allocated to the treatment sequences when they were approximately 12 weeks of age from within groups which had previously received diets with or without urea. Calves ate significantly (P< 0.001) less of silages F or FF than of silage C when each was offered alone, but when urea was given, intakes of silages F and FF were significantly (P < 0.001) increased such that the intakes of all three silages with urea were similar (23.6, 19.6, 19.3, 24.2, 24.2, 24.7 ± 0.51 g DM per kg LW for C, F, FF, Cu, Fu and FFu, respectively). Significantly (P<0.01) more of the DM in silage C was digested than in F or FF and the addition of urea significantly (P<0.05) increased the digestibility of DM from silage FF only (73.8, 71.3, 69.8, 74.6, 70.7, 72.5 ± 0.72% for C, F, FF, Cu, Fu and FFu, respectively). When the silages were given alone, calves spent longer eating and ruminating per kg DM ingested with F or FF than with C. The time spent on F and FF was significantly (P<0.01) reduced by the addition of urea (303, 388, 411, 297, 299, 290 ± 18.9 min per kg DM ingested for C, F, FF, Cu and Fu and FFu, respectively). The results presented suggest that urea partially alleviated the reduction in voluntary intake by calves given herbage preserved using formalin, but the mode of action was not clear.     

The effect of dry feed additives on the nutritive value of silage

Silages were prepared in late September from a mixed crop of perennial ryegrass and white clover with low dry matter and high nitrogen content. Six different treatments were used during ensiling; addition of either molassed sugar beet pulp or rolled barley, at 50 kg and 25 kg (t fresh grass)^?1, formic acid at 51 t^?1 and no additive (control). All silages were well fermented with low levels of ammonia and pH. The addition of rolled barley or sugar beet pulp increased the dry matter content of the silages incrementally and appeared to assist the retention of nitrogen in the silage. Dry matter intakes of silages with 50 kg of barley or sugar beet pulp tonne^?1 were similar to the control silage when fed to wether sheep but at 25 kg t^?1, dry matter intake increased by 0·15 with barley and 0·04 with sugar beet pulp compared to the control. The digestibility of dry matter (DM) and organic matter (OM) were significantly higher than the control for silages treated with formic acid or high levels of barley and sugar beet pulp whereas neutral-detergent fibre (NDF) digestibility did not appear to be significantly affected. All treated silages had a significantly higher metabolizable energy (ME) content than the control, and additions of barley or sugar beet increased the ME content. The ME intakes of all treated silages were also significantly greater than those of the control, and the formic acid-treated and low barley silages were the highest. This appeared to be associated with significantly higher energy digestibility and DM intake. Addition of rolled barley during ensilage resulted in greater nitrogen intake, availability and retention compared to additions of sugar beet pulp. The higher retention with barley silages was associated with a significantly lower proportional loss of absorbed nitrogen in urine, which indicated a more efficient utilization of nitrogen. These differences require further study to determine the mechanisms involved in the interactions between the energy source and herbage protein, both during fermentation and in the rumen.     

Fatty acid composition and nutritive value of twelve cultivars of perennial ryegrass

A comparison was made of the fatty acid composition and nutritive value of twelve cultivars of perennial ryegrass ( Lolium perenne L.) differing in heading date and ploidy level. The cultivars were sown in triplicate plots and three sequential cuts of herbage were taken at 20-d intervals during the late spring and early summer to describe the fatty acid composition and other measurements of nutritive value. Differences between cultivars were recorded for DM content ( P  <   0·01) and concentrations of gross energy, neutral-detergent fibre (NDF) and ash ( P  <   0·05). Diploid cultivars had a higher DM content and concentration of NDF ( P  <   0·01) than tetraploid cultivars whilst late-heading date cultivars had the lower NDF ( P  <   0·05), ADF and ash ( P  <   0·01) concentrations. There was variation between cultivars in fatty acid composition. Diploid cultivars had a higher concentration of C18:0 ( P  <   0·01) and C18:1 ( P  <   0·05) than tetraploid cultivars and late-heading date cultivars had the highest concentrations of total fatty acids, C16:0, C18:2 and C18:3 ( P  <   0·05). This was predominantly due to the cultivar Tyrella which is a diploid, late-heading cultivar. The study showed that some variation exists between perennial ryegrass cultivars in concentrations of polyunsaturated fatty acids, which may present opportunities to select for this trait, but further research on the developmental stages and degree of leafiness of cultivars is first required.     

The effect of additives in silages of pure timothy and timothy mixed with red clover on chemical composition and in vitro rumen fermentation characteristics

The aim was to compare the effects of additives on direct cut silages of pure timothy and timothy mixed with tetraploid red clover. First and second growth cuts were ensiled during three consecutive years, 1994, 1995 and 1996, either without any additive or with the addition of formic acid, or lactic acid bacteria in combination with molasses. Effects of the additives on the degradation characteristics of the herbage and the silages were analysed using an automatic in vitro gas production (GP) technique. At the end of the in vitro procedures, organic matter and neutral‐detergent fibre (NDF) degradabilities were determined. The tetraploid red clover persisted in the leys during the 3 years and was the dominant species at the second growth in the mixed leys. The herbage from the mixed crops had lower dry‐matter contents, higher crude protein concentrations and higher buffering capacity compared with the pure timothy at both cuts. In general, the additives reduced pH, and the concentrations of ammonium‐N and acetic acid in the silages. The treated silages had a more rapid faster GP in both crops. The silages from the mixed crop benefited more from the additives compared with the grass silages. The additives affected the soluble fractions as well as the NDF degradability of the silages of the mixed crop more than those fractions of the grass silages. The addition of molasses in combination with a commercial inocula resulted in increased production of lactic acid and ethanol in silages from both crops. The silages without additives could not meet the requirements for good silages according to the standards of the Swedish dairy industry.     

Effects of additives on the fermentation and aerobic stability of grass silages and total mixed rations

Mown herbage of timothy–meadow fescue (dry matter 218 (LDM) or 539 (HDM) g kg^?1) was ensiled in laboratory silos to evaluate silage additives. For LDM silage, additives including formic acid (a blend of formic acid, sodium formate, propionic acid, benzoic acid, glycerol and another blend of formic acid and ammonium formate, both applied at 5 L t^?1) were able to restrict fermentation and thereby improve intake potential of the silage. Aerobic stability (AS) of total mixed ration (TMR) was also improved. LDM grass treated with homofermentative lactic acid bacteria (_hoLAB) resulted in silage containing lactic acid at 132 g kg^?1 DM, ammonium‐N <40 g kg^?1 total N, and pH < 3·8, and the AS was poor (<36 h). The treatment including heterofermentative strain (Lactobacillus brevis) produced more acetic acid and better AS than _hoLAB. Salt treatment (sodium benzoate, potassium sorbate, sodium nitrite) reduced pH compared to the Control treatment (3·89 vs. 4·24) and improved AS of TMR. The LDM Control silage had good AS, but the TMR based on it had poor AS. All additives were able to lower pH on HDM silages also, but other benefits of using additives were minimal. The treatment including L. brevis on HDM was able to improve AS of TMR.     

Effect of formic acid and a bacterial inoculant on the amino acid composition of grass silage and on animal performance

An Italian ryegrass and hybrid ryegrass sward was harvested on 11 May 1994. The mean dry‐matter (DM) content of the herbage was 197 g kg^–1 fresh matter (FM), and mean nitrogen and water‐soluble carbohydrate contents were 20 and 272 g kg^–1 DM respectively. Approximately 72% of total nitrogen (TN) was in the form of protein‐nitrogen. The herbage was treated with either no additive, formic acid (3·3 l t^–1) (Add‐F, BP) or inoculant (2·3 l t^–1) (Live‐system, Genus) and ensiled in 100 t silos. Changes in effluent composition with time showed that silage fermentation and protein breakdown were delayed by treatment with formic acid. Formic acid and inoculant treatments also inhibited amino acid catabolism during ensilage. All silages were well fermented at opening with pH values < 4·0 and ammonia‐N concentrations of ≤ 50 g kg^–1 TN after 120 d ensilage. Treatment had an effect on protein breakdown as measured by free amino acid concentration, with values of 21·5, 18·2 and 13·2 mol kg^–1 N at opening (191 d) for untreated, formic acid‐treated and inoculated silages respectively. Amino acid catabolism occurred to the greatest extent in untreated silages with significant decreases in glutamic acid, lysine and arginine, and increases in gamma amino butyric acid and ornithine. The silages were offered ad libitum without concentrate supplementation to thirty‐six Charolais beef steers for a period of 69 d (mean live weight 401 kg). Silage dry‐matter intakes and liveweight gains were significantly (P < 0·05) higher on the treated silages. Silage dry‐matter intakes were 7·42, 8·41 and 8·23 kg d^–1 (s.e.d. 0·27) with liveweight gains of 0·66, 0·94 and 0·89 kg d^–1 (s.e.d. 0·058) for untreated, formic acid‐treated and inoculated silage‐fed cattle respectively. In conclusion, additives increased the intake of silage and liveweight gain by the beef steers, and it is suggested that this may be caused in part by the amino acid balance in these silages.     

The relationship between amino acid composition and nutritive value for plant and animal protein concentrates

Evaluation by a chick growth test of mixtures of protein concentrates with cereals did not always confirm quality predictions based upon amino acid composition, but predictions based upon the content of the first limiting amino acid—the Chemical Score—were more generally useful when the concentrates were fed to chicks or rats as a sole protein source. Predictions involving a number of essential amino acids were no more useful than Chemical Score. A knowledge of amino acid deficiencies alone is not sufficient for the prediction of performance under practical conditions.     

The effect of an acid salt-type additive on the fermentation of grass silages made in bunker silos on commercial dairy farms in Wales

The fermentation characteristics and chemical composition of 57 first-cut and 30 second-cut samples of grass silages, made in bunker silos on commercial dairy farms in Wales in 1990, and treated with a nominal 61 t⁻¹ of an acid salt-type additive at ensilage, is described. Typical chemical composition of grass cut for ensilage was 156 g kg⁻¹ dry matter (DM) and 28 g kg⁻¹ water soluble carbohydrate (WSC), with 181 g (kg DM) ⁻¹ crude protein (CP) and 232 g (kg DM) ⁻¹ modified acid detergent fibre (MADF). The effect of additive use was to produce silages with DM 230 g kg⁻¹ pH 3·93, ammonia N 70 g kg⁻¹ total N, with residual WSC 35 g (kg DM) ⁻¹, lactic acid 83 g (kg DM) ⁻¹, total acids 118 g (kg DM) ⁻¹ and butyric acid 0·7 g (kg DM) ⁻¹. No significant differences were found between first- and second-cut silages. Silage fermentation was restricted (i.e. lactic acid less than 60 g kg DM⁻¹) in only 20% of the samples.
It is suggested that on commercial farms the application rate achieved may be insufficient to produce a restricted fermentation.