Effect of long-term application of animal slurries to grass on silage feeding quality for sheep

The effect of slurry type (pig or cow) and use of a bacterial silage inoculant, was assessed on herbage from long-term slurry plots ensiled in pilot-scale (0·7 tonne) silos. Silage was fed to sheep to assess digestibility and metabolisable energy content. The latter was measured by direct calorimetry in a modified cattle respiration chamber. Non-inoculated slurry-treated silages had poorer fermentation quality than inoculant-treated silages (P < 0·001) and silages treated with cow slurry had poorer fermentation quality than those treated with pig slurry (P < 0·001). Digestibility values for different components of the silages showed few differences. Energy digestibility values of pig slurry-treated silages were lower (P < 0·05) than for cow slurry-treated silages. Methane production from all animals in the experiment was comparatively low at 5·97–6·74% of gross energy intake. Metabolisable energy contents of the cow slurry-treated silages were higher than pig slurry-treated silages (P < 0·05) and the ME contents of inoculant treated silages were higher than of non-inoculated silages (P < 0·001). Thus, treatment of slurry-treated silages with bacterial inoculant enhanced fermentation quality and ME contents. The effect of slurry type on fermentation quality and feeding value was ambiguous; cow slurry-treated silages exhibiting poorer fermentation quality but higher ME contents than equivalent pig slurry-treated silages. © 1998 Society of Chemical Industry.     

Effects of Silage Fermentation and Post-ruminal Casein Supplementation in Lactating Dairy Cows: 1—Diet Digestion and Milk Production

Two silages were prepared from the first-cut sward of timothy-meadow fescue and wilted to a dry matter (DM) content of 300 g kg^-1. One was ensiled with the addition of a formic-acid-based additive (4 litres formic acid (FA) per tonne) and the other with the addition of a bacterial inoculant (LAB) at a rate of 5×10⁶ colony forming units g^-1. Both silages were well preserved, but the extent of fermentation was greater in LAB-silage than in FA-silage as indicated by a lower concentration of water soluble carbohydrates (68 vs 177 g kg^-1 DM) and a higher concentration of lactic acid (147 vs 32 g kg^-1 DM). Four Ayrshire cows were used in a 4×4 Latin square experiment with 21-day periods to study the effects of silage fermentation and postruminal casein supplementation on silage intake, nutrient supply and milk production. The four treatments were FA-silage without casein (FA-0), LAB-silage without casein (LAB-0), FA-silage with casein (FA-C) and LAB-silage with casein (LAB-C). Both silages were given ad libitum with 8 kg day^-1 of barley without or with 400 g day^-1 of casein infused into the duodenum. Organic matter digestibility was lower (0·723 vs 0·753; P<0·01) for FA-silage than for LAB-silage. Cows offered FA-silage had a higher molar proportion of acetate and a lower proportion of propionate in ruminal fluid than cows offered LAB-silage. Microbial protein synthesis estimated from the output of purine derivatives in urine was greater (288 vs 260 g N day^-1; P<0·05) for cows given FA-silage compared with LAB-silage. Feeding LAB-treated silage tended (P<0·10) to decrease silage DM intake compared with FA-treated silage (10·61 vs 11·77 kg DM day^-1). Silage composition did not affect significantly milk yield or milk composition. Casein infusion increased milk yield (25·1 vs 27·1 kg day^-1; P<0·05), milk protein content (32·4 vs 33·8 g kg^-1; P<0·05) and protein yield (808 vs 905 g day^-1; P<0·01). The responses were similar for both silages. © 1997 SCI.     

Effects of Silage Fermentation and Post-ruminal Casein Supplementation in Lactating Dairy Cows: 2—Energy Metabolites and Plasma Amino Acids

Four cows were used in a 4×4 Latin square design with a 2×2 factorial arrangement of treatments to examine the effects of the extent of silage fermentation and post-ruminal casein infusion on the arterial concentrations and mammary arterial–venous (A–V) difference of energy-yielding nutrients and plasma amino acids. Of the two silages one was preserved with formic acid (FA-silage) and the other with an inoculant of lactic acid bacteria (LAB-silage). Both silages were given ad libitum with 8 kg day^-1 of barley, without or with duodenal casein infusing (400 g day^-1). Blood was sampled from the coccygeal vessel and milk vein. FA-silage less fermented than LAB-silage as indicated by higher concentration (g kg^-1 dry matter) of water soluble carbohydrates (178 vs 68) and lower concentration of lactic acid (32 vs 147). Plasma concentration of glucose was lower (P<0·05) and concentrations of essential amino acids (P<0·001) and blood β-hydroxybutyrate (BHB) (P<0·01) were higher with FA-silage than with LAB-silage. There was a strong linear relationship between arterial concentration and mammary A–V difference of blood metabolites, except BHB, and amino acids. The relationship between arterial concentration and mammary A–V difference of glucose was different between the silages. Mammary extraction rates of glucose, BHB, histidine, leucine and lysine were affected by their arterial concentrations. The interaction between silage fermentation and casein infusion was significant (P<0·05) in arterial concentration of branched-chain amino acids, the increase being greater with FA-silage than with LAB-silage. The results suggest that the supply of glucose may limit milk synthesis in cows given restrictively fermented grass silage and barley, whereas the supply of amino acids may be more limiting with extensively fermented silages. It is further suggested that the mammary gland has a capacity to adapt it's efficiency of nutrient uptake according to the supply and mammary demand of nutrients. © 1997 SCI.     

Chemical characterisation and ruminal nutrient degradability of hulled and hull-less oats

The objectives of this study were to determine the chemical and ruminal nutrient degradability characteristics of two hulled (Calibre and AC Mustang) and one hull-less (AC Belmont) oat varieties. Ruminal nutrient degradability characteristics of the oat varieties were determined relative to barley using one ruminally fistulated cow. Neutral (NDF) and acid (ADF) detergent fibre levels were higher (P < 0·05) in hulled than hull-less oats. Hulled AC Mustang had higher (P < 0·05) NDF and ADF content than hulled Calibre. Starch content was higher (P < 0·05) in AC Belmont (590 g kg⁻¹) than Calibre (457 g kg⁻¹) and was higher in Calibre than AC Mustang (415 g kg⁻¹). Crude protein was higher (P < 0·05) in hull-less than hulled oat. Both hulled varieties had similar CP content (average 124 g kg⁻¹). Estimated digestible energy value was highest (P < 0·05) for AC Belmont (16·94 MJ kg⁻¹), intermediate for Calibre (14·18 MJ kg⁻¹) and lowest for AC Mustang (13·34 MJ kg⁻¹). Ruminal dry matter and NDF degradability were higher (P < 0·05) in hull-less than barley and was higher in barley than hulled oats. Ruminal starch degradability exceeded 900 g kg⁻¹ for all tested feeds and had the order AC Belmont = barley > Calibre = AC Mustang. It was concluded that oat varieties used in this study varied considerably in their chemical composition and ruminal degradability. When compared with barley, hulled oats had lower while hull-less oats had higher ruminal degradability. © 1998 SCI.     

Effects of exogenous fibrolytic enzymes on epiphytic microbial populations and in vitro digestion of silage

Epiphytic microbial populations, reducing sugar (RS) concentrations and in vitro fermentation were measured in unsterilised and sterilised barley silage and corn silage treated with an exogenous enzyme preparation. Enzyme treatments comprised spraying silages (10 ml kg^?1 DM) with a xylanase/β‐glucanase enzyme preparation or with water or autoclaved enzyme (controls). In Experiment 1, autoclaving the silages increased (P < 0.05) concentrations of RS present 24 h after treatment. Enzymes increased (P < 0.05) RS in both fresh and autoclaved silages, more so (P < 0.05) with autoclaving than without. Autoclaved enzymes did not affect RS concentrations relative to the (water) controls. Aerobic exposure of corn silage numerically increased microbial numbers; no microbial viability was detected in autoclaved silages. Enzymes increased (P < 0.05) total bacterial counts in all silage types, and this effect was more pronounced on aerobically exposed silage. In Experiment 2, RS concentrations were determined 0 and 24 h after enzyme treatment of silages unsterilised or sterilised with ethylene oxide (EO). Irrespective of EO or silage type, RS concentrations were higher (P < 0.05) 24 h after enzyme treatment than immediately after (0 h). In enzyme‐treated silages, 24 h RS concentrations were higher (P < 0.05) with EO than without. Reducing epiphytic microbiota by sterilisation conserved enzyme‐liberated RS in the silages. Aerobic exposure before applying enzymes enhanced RS‐associated increases in microbial numbers. Enzymes effectively released RS from silages, but utilisation of the RS by inherent epiphytic micro‐organisms may limit their availability to the ruminant. By releasing RS, exogenous enzymes may encourage silage deterioration if the interval between treatment and feeding is excessive. During in vitro incubation of freeze‐dried silages (Experiment 3), incorporation of ¹⁵N into microbial N was decreased by enzyme applied to fresh silage (before drying), but increased by enzyme applied after the silage had been dried. Moisture level of feeds and epiphytic microbial populations may influence the effectiveness of enzyme treatment for enhancing utilisation of feeds by ruminants. For the Department of Agriculture and Agri‐Food, Government of Canada. © Minister of Public Works and Government Services Canada 2002. Published for SCI by John Wiley & Sons, Ltd     

Ensiling characteristics and ruminal degradation of Italian ryegrass and lucerne silages treated with cell wall-degrading enzymes

Two experiments were carried out to investigate the effect of added cell wall-degrading enzymes at ensiling on the fermentation and in situ degradation of grass and legume silages. Primary growths of Italian ryegrass (Lolium multiflorum Lam) and lucerne (Medicago sativa L) were wilted and ensiled in laboratory-scale silos with or without enzymes. Silages were opened at 2, 5, 15 and 45 days after storage; the fermentation quality and the contents of cell wall components (NDF, ADF, ADL) were determined. The 45 day silages were subjected to in situ incubation experiments, and the kinetics of DM and NDF degradation was estimated. The enzyme treatment enhanced the lactic acid production (P < 0.01) and reduced the pH value (P < 0.01) of both Italian ryegrass and lucerne silages. The contents of cell wall components, however, were not affected by enzymes, except for NDF of Italian ryegrass silage. The in situ incubation experiments revealed that added enzymes increased the rapidly degradable DM (P < 0.01) and appeared to decrease the rate of degradation of DM and NDF of Italian ryegrass silage. The rapidly degradable DM was not altered when lucerne was treated, but the rate of degradation of NDF was significantly reduced (P < 0.05). These results suggest that although added cell wall-degrading enzymes could improve the preservation of grass and legume silages, the effects on ruminal degradation may be different according to the herbage treated. Enzymatic hydrolysis during ensilage may be restricted to easily digestible cell walls, leaving relatively less digestible components that would be retained in treated silages. © 1999 Society of Chemical Industry     

Effects of intraruminal infusions of propionate and butyrate with two different protein supplements on milk production and blood metabolites in dairy cows receiving grass silage-based diet

Four cows were used in a balanced 4×4 Latin square with 2 week experimental periods to investigate the effects of intraruminal infusions of volatile fatty acids and protein source on milk production and blood metabolites. The four treatments in a 2×2 factorial arrangement were isoenergetic intraruminal infusions of propionate (500 g day⁻¹) or butyrate (417 g day⁻¹) each given with isonitrogenous protein supplementation of fish meal (FM) or barley protein (BP). The cows were fed restrictively with 9 kg dry matter day⁻¹ of formic acid treated grass silage and 8 kg day⁻¹ of concentrate. Propionate infusion increased milk yield (24·9 vs 23·4 kg day⁻¹; P<0·05), milk protein yield (832 vs 778 g day⁻¹; P=0·05) and milk lactose content (44·7 vs 43·5 g kg⁻¹; P<0·05) and yield (1113 vs 1023 g day⁻¹; P<0·01), whereas butyrate infusion was associated with a higher milk fat content (44·7 vs 39·4 g kg⁻¹; P<0·01) and yield (1033 vs 974 g day⁻¹; P<0·01). FM tended (P<0·10) to increase milk yield, but had no significant effects on milk composition or milk component yields compared with BP. Butyrate infusion increased blood ketones, plasma non-esterified fatty acids and glycine relative to propionate infusion. The concentrations of ammonia N in rumen fluid and urea in plasma and milk were similar for both protein supplements. The profile of amino acids in plasma was similar for both protein supplements except for the higher concentrations of phenylalanine, proline and tyrosine with BP. The results show that protein utilisation can be improved by increasing the supply of propionate from rumen fermentation in cows given a grass silage-based diet. © 1998 SCI.     

Effect of Yeast Culture Supplement on Ruminal Microbial Populations and Metabolism in Buffalo Calves Fed a High Roughage Diet

The effect of Saccharomyces cerevisiae yeast culture (YC, Yea-Sacc 1026) as a supplement to the high-roughage diet of buffalo calves on the rumen microbial populations, fermentation pattern and in sacco dry matter disappearance of dietary constituents was examined. A control group was fed a diet consisting of, on a dry matter basis, 2·12 kg bajra (Pennisetum typhoides) hay and 0·45 kg groundnut cake per day per calf, while the treatment group had the same diet plus 5 g YC. After feeding for 6 weeks, inclusion of YC was stopped and both groups were given the control diet for 2 weeks. At week 4 the pH in the rumen fluid (RF) was significantly higher (P<0·05) up to 6 h post-feeding in the treatment group compared with the control group. The concentrations of total, total viable and cellulolytic bacteria were increased by 41·0 (P<0·05), 33·5 and 57·4% (P<0·01), respectively, with YC supplement. The concentration of total volatile fatty acids (P<0·05), particularly at 4 h post-feeding (P<0·01) and acetate (P<0·01) and acetate to propionate ratio (P<0·05) were higher in the treatment compared with the control group. On YC supplementation, the concentration of NH₃-N was decreased (P<0·05) while that of TCA-precipitable protein in RF was marginally but non-significantly increased. Withdrawal of YC from the diet reversed these effects and the rumen variables returned to values close to control levels after 2 weeks. The in sacco dry matter disappearance of dietary components was higher in the treatment compared with the control group, particularly during the first 24 h of incubation. © 1997 SCI.     

The effect of addition of mixtures of amino acids on the intake of grass silage by sheep and cattle

A mixture of 15 amino acids was either added to the basal silage diet (sheep and cattle) or infused intraruminally (cattle) to determine the role of amino acids in the control of silage intake. Neither dietary addition nor intraruminal infusion of the amino acid mixture in sheep or cattle had a significant effect on intake compared to the control (P > 0·05). However, in cattle, dietary addition of the amino acid mixture increased intake compared with intraruminal infusion of the amino acid mixture (P < 0·01). It was concluded that the amino acid content of the basal silage is not involved in the control of silage intake by sheep or cattle. © 1998 SCI     

Laboratory evaluation of previously fermented juice as a fermentation stimulant for lucerne silage

The potential use of forage juice anaerobically stored for 2 days (previously fermented juice, PFJ) as a silage additive was investigated. Lucerne (450 g) was ensiled in laboratory‐scale silos (900 ml capacity) with or without sucrose (20 g kg⁻¹) or PFJ (2.5 ml kg⁻¹). Silages treated with both additives were also made and fermentation quality, in vitro dry matter digestibility and in vitro ruminal NH₃ production were determined. The control silage showed very poor quality with high butyrate and NH₃‐N concentrations. Addition of sucrose significantly increased lactate but failed to inhibit the deterioration by clostridial fermentation. Use of PFJ further increased lactate and greatly reduced butyrate and NH₃‐N production during storage. The combination of sucrose and PFJ was more effective in improving fermentation than either additive on its own. In vitro digestibility appeared to be higher when lucerne was well preserved. Ruminal NH₃ production in vitro was decreased in silages with sucrose and PFJ added at ensiling. This result indicates that use of PFJ can be a promising way to stimulate lactate production in some difficult direct cut silage. The potential of improving fermentation may be comparable to conventional sugar additives. © 1999 Society of Chemical Industry     

Response of pancreatic secretions to feeding diets with low and high levels of soybean trypsin inhibitors in growing pigs

Studies were carried out to determine the effect of soybean trypsin inhibitors (SBTI) on exocrine pancreatic secretions in growing pigs. Six barrows with an average initial body weight (BW) of 27·1±1·4 kg were fitted with permanent pancreatic re-entrant cannulas and fed two diets according to a crossover design. Two maize starch-based diets were formulated to contain 200 g kg⁻¹ crude protein from either Nutrisoy (food grade defatted soy flour) or autoclaved Nutrisoy. The concentrations of SBTI in Nutrisoy and autoclaved Nutrisoy diets were 13·4 and 3·0 g kg⁻¹, respectively. The experiment consisted of two periods of 9 days each. The average BW at the start of the first and second experimental periods was 33·5±2·7 and 37·2±3·7 kg, respectively. The average BW at the conclusion of the experiment was 41·8±3·9 kg. The volume of pancreatic secretion was higher (P<0·01) when the Nutrisoy, as opposed to the autoclaved Nutrisoy diet was fed (3804 vs 2634 ml (24 h)⁻¹). The concen-tration of nitrogen and protein and specific activities (units litre⁻¹) of amylase, chymotrypsin and trypsin were lower (P<0·05) in pancreatic juice of pigs fed the Nutrisoy diet. There were no differences (P>0·05) in the total secretions of nitrogen (g (24 h)⁻¹) and total activities (units (24 h)⁻¹) of amylase, lipase, chymotrypsin and trypsin in pancreatic juice of pigs fed the Nutrisoy and autoclaved Nutrisoy diets. However, the total secretion of protein was slightly higher (25·7 vs 22·8 g (24 h)⁻¹; P<0·05) in pancreatic juice of pigs fed the autoclaved Nutrisoy diet, which corresponded with the increase in the secretion of protein-bound amino acids. There was also an increase in the total secretion of free amino acids in pancreatic juice. These studies show no effect of SBTI on the total enzyme activities in pancreatic juice of growing pigs. © 1998 SCI.     

In vitro fermentation of beet fibre and barley bran,of their insoluble residues after digestion and of ileal effluents

The main objective of this study was to determine the form in which beet and barley bran fibres reach the colon, and to evaluate the influence of endogeneous compounds on their patterns of fermentation. Raw fibres (RF), corresponding ileal effluents (IE) from pigs, and insoluble fibre residues (IR) extracted from IE, were fermented with human faecal inoculum for 24 h in an in vitro batch system. For beet fibre, rate but not extent of cell wall sugars degradation was increased (+34% at 6 h, P<0·05) after oroileal transit, due to a more porous structure. For barley bran, oroileal conditions degraded endosperm compounds such as β-glucans, leading to a lower extent of cell wall glucose fermentation compared with RF (-22% at 24 h, P<0·05). In the presence of endogeneous substances, degradation of beet fibre polysaccharides was delayed (P<0·05) at each incubation time but that of barley bran fibre was unaltered. Compared to RF, IR and IE significantly exhibited lower acetate production for beet fibre, and higher propionate and lower butyrate production for barley bran after 24 h. It is concluded that in vivo digestion modified fermentation patterns of both fibres in a manner depending on botanical structure. ©1997 SCI     

Comparative composition of aerial and subterranean potato tubers (Solanum tuberosum L)

The composition of aerial and subterranean tubers of two potato genotypes cvs Desiree (red skin) and Epicure (white skin) was compared immediately after harvest using a range of analytical methods. Irrespective of genotype, aspartic acid, arginine, glycine, glutamic acid, histidine, leucine, serine, threonine and total amino acid concentrations were significantly higher (P<0·05) in aerial compared with subterranean tuber tissue. Significant increases (P<0·05) in valine in aerial tubers, but no significant differences in alanine, tyrosine and iso-leucine, when compared with subterranean tubers of cv Desiree, were found. In cv Epicure, alanine, tyrosine and iso-leucine were significantly higher in aerial tubers (P<0·05); however, no significant differences in valine were recorded. There was no significant increases in lysine and phenylalanine between tuber types. Regardless of genotype α-solanine, α-chaconine, chlorogenic acid, chlorophyll and crude protein concentrations were significantly higher in aerial tubers compared with subterranean ones (P<0·01). No significant increases in total lipids between tuber types were found. In cv Desiree, ascorbic acid content was not significantly different between aerial and subterranean tuber tissue, but in cv Epicure concentrations were significantly higher (P<0·01) in aerial tubers. Starch concentrations were significantly higher in subterranean tubers of both cultivars (P<0·05). Sugar content was significantly higher in aerial tubers of cv Epicure (P<0·01), but not significantly different between aerial and subterranean tubers of cv Desiree. Regardless of genotype, phosphorus, magnesium, potassium, zinc, manganese and sodium concentrations were significantly higher (P<0·05) in aerial tubers. Iron and copper concentrations were significantly higher in aerial tubers of cv Desiree (P<0·01), but significantly less in cv Epicure compared with subterranean tubers (P<0·01, P<0·05). Calcium concentrations were not significantly different between aerial and subterranean tubers of cv Desiree, but significantly higher in aerial tuber tissue of cv Epicure (P<0·01). Total gross energy (mJ kg⁻¹ FW) was higher in aerial tubers of cv Desiree compared with subterranean tubers (P>0·05), but not significantly different between aerial and subterranean tubers of cv Epicure. The potential applications of aerial tubers for industrial purposes are discussed. © 1997 SCI.     

Caecal metabolites and microbial populations in chickens consuming diets containing a mined humate compound

The objectives of this study were to compare the short-chain fatty acid (SCFA) concentrations, amino acid concentrations and key carbohydrate-fermenting anaerobic bacterial populations in the caeca of chickens consuming either control diets or a mined humate compound (MH; Menefee Humate^TM). Dietary MH at concentrations of 0, 5 or 10 g kg⁻¹ did not affect (P ⩾ 0·05) the caecal concentrations of SCFA and amino acids. Regardless of treatment, acetate was found to be the predominant SCFA in the caecum followed by propionate (P < 0·05). MH had no effect on the caecal concentrations of 17 amino acids compared with control birds but, when analysed across treatments, glutamate was found to be the predominant free amino acid in the caecum, followed by alanine (P < 0·05). MH did not significantly influence any of the anaerobic microbial populations but Escherichia coli populations from birds receiving either 10 or 50 g kg⁻¹ MH were between 10 and 100 times greater than control birds (P < 0·05). It appears that MH does not influence concentrations of fermentation acids or amino acids in the caecum but may influence levels of individual microbial populations. © 1998 SCI.     

Ozonated cotton stalks as a silage additive: Fermentation data on lucerne with particular reference to protein degradation

Fermentation patterns of lucerne silages were studied in laboratory silos. The treatments consisted of: (a) fresh (200 g kg>^?l DM) lucerne, ensiled without any treatment (L); (b) lucerne wilted to 525 g kg^?1 DM prior to ensilage (WL); (c) fresh lucerne + cotton stalks at a ratio of 60:40 on a dry matter (DM) basis (L + CS); and (d) fresh lucerne + ozone-treated cotton stalks at the same ratio as above (L+O₃). Silos were opened after 90 days and the silages analysed. The highest DM loss was found in the L silage (14·7%), whereas in the L+O₃ silage DM loss was practically nil. Both wilting and the addition of untreated cotton stalks proved to be effective in reducing DM losses during fermentation. The production of lactic acid and volatile organic acids in the L+ O₃ and WL silages was lower than in the L and L+CS silages. The poorest ability to preserve forage protein was found in the L silage, in which only 28 % of the protein was recovered after 90 days. The greatest ability to preserve protein was found in the L+O₃ silage, in which 78 % of the protein was maintained. Ammonia production followed generally similar patterns. Amino acids underwent extensive degradation in the L silage. Recovery of amino acids in the WL silage was in the range 69–93 %, and in the L + O₃ silage it was almost complete. Ozonated CS proved to be a good silage additive with respect to energy and protein preservation. Its future use in the field would allow direct ensilage of fresh leguminous material immediately after harvest, producing a high quality silage.     

Effects of peptidase inhibitors and other additives on fermentation and nitrogen distribution in perennial ryegrass silage

The effects of formic acid, three concentrations of formaldehyde in a formic acid/formaldehyde mixture and cysteine‐peptidase inhibitors, 1‐trans epoxysuccinyl‐leucylamido‐(4‐guanidino) butane (E‐64), N‐ethylmaleimide and cystamine on nitrogen (N) distribution during ensilage of perennial ryegrass (Lolium perenne) were investigated. A third cut or perennial ryegrass (163 g dry matter kg⁻¹ and 61 g water‐soluble carbohydrate kg⁻¹ dry matter) was ensiled in two silo sizes; formaldehyde‐treated herbage was ensiled only in larger silos (500–550 g herbage) and cysteine‐peptidase inhibitor‐treated herbage only in smaller silos (130–150 g herbage). Control silages were poorly fermented but contained low concentrations of butyric acid and ammonia N indicating little activity of spoilage bacteria. Formic acid increased peptide N concentrations (P<0.01) in silage from smaller silos but had little effect on other N constituents; in the larger silos, formic acid reduced soluble non protein nitrogen (NPN) and ammonia‐N concentrations and increased peptide N concentrations. Increments in formaldehyde reduced silage soluble and ammonia N concentrations (linear effect; P<0.001). N‐Ethylmaleimide and E‐64 reduced soluble NPN concentrations (P<0.05) but had little effect on other N constituents. Cystamine, however, increased silage peptide N concentrations. Gel filtration on Sephadex G‐25 of silage juice prepared from control and formic acid‐treated silages suggested that most silage peptides were small, with molecular weights of less than 520 Da. © 1999 Society of Chemical Industry     

Ensilage as a means of reducing the concentration of cyanogenic glycosides in the pods of Acacia sieberiana and the effect of additives on silage quality

Cyanogenic glycosides are anti‐nutritional components capable of liberating hydrogen cyanide, a respiratory poison that has been reported to be responsible for the death of livestock that browse some Acacia species containing these compounds. The objective of the study was to improve the nutritive value of the pods of Acacia sieberiana by reducing their contents of cyanogenic glycosides through ensiling, and to examine the influence of various levels of added molasses and urea on the aerobic stability of the silage. In experiment 1, laboratory silages, prepared by mixing ground pods with water in two ratios (60:40 and 40:60 w/w pod material:water), were put into 250 ml polythene bottles, ensiled for 4, 7, 14, 21, 28 or 35 days and analyzed for cyanide. In experiment 2, silages prepared as described above but using only one of the ratios (40:60), and with the addition of molasses (0, 30 or 60 g kg^?1) and urea (0, 2.5 or 50 g kg^?1) were included in a 3 × 3 factorial design, to study the effects of these additives on the stability of the silage. The period of ensilage was 14 days. In experiment 3, the concentrations of molasses and urea were modified to 0, 45 or 90 g kg^?1 and 0, 7.5 or 15 g kg^?1, respectively, and the period of ensilage was extended to 45 days. The parent material contained 130.6 mg CN kg^?1 DM and ensiling the material for 35 days reduced the concentration to 18.1 mg CN kg^?1 DM. Moisture content at ensiling significantly (P < 0.001) affected the concentration of cyanide in the stored silages. Silages opened after 14 days were unstable irrespective of the use of additives. However those with combined urea and molasses exhibited a slow rate of deterioration and low fungal counts. Extending the period of ensiling to 45 days improved the aerobic stability of all the silages. The addition of urea significantly (P < 0.001) increased the pH, crude protein content, gross energy and fermentation acids while molasses treatment increased (P < 0.001) the lactic acid and ash content of the silages. Ensiling ground pods for 45 days was enough to reduce the cyanide content to non‐toxic levels and produced a silage which was aerobically stable, while the inclusion of additives further improved the quality of the silages. Copyright © 2004 Society of Chemical Industry     

Cassava and soyabean flours and resting time effects on sensory and physical characteristics of reconstituted miondo

Sensory and physical characteristics of miondo made with three types of cassava flour (CF) (CF1, shredding of roots and drying; CF2, shredding of roots, 24-h natural fermentation, and drying; CF3, 3-day steeping of roots and drying) containing 0, 5 and 10% of added soybean flour (SF) were evaluated after 0, 1, 2, 3 and 4 h of resting (RT) before cooking to determine the optimum CF and SF levels and RT. Results indicated that miondo made with CF3 were more palatable (P<0·05) and firmer (P<0·05) than those of CF1 and CF2. Upon resting, there was no significant changes in sensory characteristics of cooked miondo, although the instrumental firmness (hardness) of miondo (made with CF3) increased (P<0·05). Upon addition of SF, products became less palatable, more yellow in colour, softer, less sticky; weight loss of raw miondo decreased; water retention ratio (WRR), crude protein contents, and total ashes of CF3 increased. WRR and protein content of CF3–SF blends correlated negatively with hardness of miondo (r=-0·90 and -0·99, respectively). CF3 with no added SF was most appropriate for making palatable miondo, regardless of the resting time. © 1998 SCI.     

Effect of long-term application of animal slurries to grassland on silage quality assessed in laboratory silos

The effect on silage quality of slurry type (pig or cow), rate of application of slurry (50, 100 or 200 m³ ha^?1 year^?1) and use of a bacterial silage inoculant, was assessed on grass from a long-term slurry experiment ensiled in laboratory silos. There was no significant effect of slurry type or the quality of silage made from grass re growths. However, on the basis of ammonia-N, lactate and volatile fatty acid contents, spring (first cut) grass treated with cow slurry in both years of the study produced significantly poorer fermentation (P < 0.001) than silage from grass treated with pig slurry. The quality of silage made from slurry-treated swards compared favourably with that from swards treated with granular fertiliser. Although increasing the rate of slurry application was shown to reduce fermentation quality in most treatments, this was seen as an effect of increasing the total-N content of the herbage rather than of slurry application per se. From a study, in selected treatments, of the bacterial flora at harvest, it was also observed that slurry application had little impact on either the composition or diversity of herbage enter bacteria at harvest, and therefore probably upon subsequent fermentation. No evidence was found for the occurrence of clostridia on herbage from slurry-treated swards. Use of a bacterial inoculant (Ecosyl; ICI plc) improved fermentation quality significantly (P < 0.001) even where high rates of slurry (200 m³ ha^?1 year^?1) had been applied to swards. The high acetate and butyrate contents typical of laboratory silages untreated with additive were not seen in the inoculated silages.     

Cellulase and Bacterial Inoculant Effects on Cocksfoot and Lucerne Ensiled at High Dry Matter Levels

Limited information exists on the response of grass and legume silage to enzyme and bacterial inoculant treatments when wilted to drier than desired conditions. This study was undertaken to evaluate the impact of cellulase (from Trichoderma longibrachiatum) application rate, when combined with a bacterial inoculant (Lactobacillus plantarum and Pediococcus cerevisiae), on the fermentation characteristics of cocksfoot (Dactylis glomerata L) and lucerne (Medicago sativa L) ensiled at high dry-matter concentrations. Forages were wilted to near 600 g dry matter kg^-1 and cellulase, combined with inoculant, was applied at 0·30 ml kg^-1 herbage and at two, four and eight times this concentration (at least 2500 IU ml^-1). Cellulase was also applied alone at 0·60 ml kg^-1. Wilted forages were ensiled in laboratory silos for 60 days. Effect of cellulase application rate on neutral detergent fibre concentrations of the silages was small and inconsistent. Averaged across species, only the intermediate cellulase concentrations decreased neutral detergent fibre concentration (P=0·082). The limited cell-wall degradation was probably related to the high silage dry-matter and lignin concentrations. Cellulase combined with inoculant increased total fermentation, when averaged across species. In cocksfoot, cellulase combined with inoculant decreased pH and NH₃-N concentration but increased the lactic: acetic acid ratio of control silage, with most of the effect caused by the inoculant. Cellulase applied alone to lucerne caused a higher lactic: acetic acid ratio than the control or when combined with the inoculant at the same cellulase rate. Thus, the effect of cellulase–inoculant mixtures on silage quality varied among plant species, with cocksfoot generally more responsive than lucerne. © 1997 SCI.