Determination of volatile fatty acids C1–C6, and lactic acid in silage juice

A method for the determination of volatile fatty acids, C₁–C₆, and lactic acid in silage juice is described. The procedure is simple and capable of application to large numbers of samples. It involves separation of the free acids by ion exchange, formation of their benzyl esters by the addition of benzyl bromide to a solution of the tetrabutylammonium salts in acetone and ultimate determination by gas liquid chromatography.     

A comparison between red clover silage and grass silage feeding on fatty acid composition, meat stability and sensory quality of the M. Longissimus muscle of dairy cull cows

Sixteen Holstein–Friesian dairy cull cows were offered either ad libitum grass (G) or red clover (RC) silage for 12 weeks. Dry matter (DM), total nitrogen, and pH was higher for the RC than the G silage and organic matter, water-soluble carbohydrate, fibre, DM digestibility, ammonia-N, vitamin E and acetic acid higher for the G silage (P < 0.05). Fatty acid compositions were different (P < 0.05) with G silage having higher levels of C12:0, C14:0, C16:1cis−9, C18:3n−3 and total fatty acids whereas RC had higher levels of C18:0, C18:2n−6 and C20:0. Daily liveweight gain was high and not different between groups (average 1.22 kg/d). Body condition score and back fat thickness at slaughter along with conformation, fat grade and slaughter weight were not different between groups. Animals offered the G silage produced larger M. longissimus length (P < 0.01) and a trend (P < 0.1) for width. RC fed animals had higher proportions of C18:3n−3 (P < 0.001), total n−3 fatty acids (P < 0.01) and total PUFA compared to animals offered the G silage despite greater intakes of these fatty acids on G (P < 0.001). Vitamin E concentration and stability of aged meat during simulated retail display, were lower (P < 0.05) from animals offered RC than animals offered G. Shear force and ultimate pH, however were not different in steaks and sensory attributes were similar; the only difference being a higher score (P < 0.01) for fishy in the RC steaks. The results suggest that feeding high DMD silage to dairy cull cows can result in a high standard of finish and liveweight gain. Furthermore RC silage as opposed to G silage can increase the beneficial fatty acid profile of the resultant meat.     

Microbiological screening of the straight chain fatty acids (C1-C12) as potential silage additives.

A microbiological screening procedure was used to assess the potential of each of the straight chain members of the series of fatty acids, formic to lauric inclusive, as silage additives. Thirty-four pure cultures of microorganisms were subjected to serial dilutions of each of the acids in broth buffered at unit pH intervals between 3 and 6 inclusive. All the fatty acids of the series appeared to have potential; the lower members (C₁-C₇) prevented the growth of spore-bearing bacteria and the higher acids had more general antimicrobial effects. A consistent feature of the data obtained was the increase in antimicrobial activity with a decline in pH.     

Effects of corn silage particle length and forage:concentrate ratio on milk fatty acid composition in dairy cows fed supplemental flaxseed

This study aimed to evaluate the effects of length of chop of corn silage and forage:concentrate ratio (F:C) on performance and milk fatty acid profiles in dairy cows supplemented with flaxseed. Our hypothesis was that decreasing forage particle length and F:C ratio would increase unsaturated fatty acid flow to the small intestine and subsequent transfer of these unsaturated fatty acids into milk. Eight Holstein cows (648.1 ± 71.5 kg body weight; 109.6 ± 43.6 days in milk) were used in a replicated 4 × 4 Latin square design with 21-d periods and a 2 × 2 factorial arrangement of dietary treatments. Dietary factors were: 1) F:C ratios (dry matter basis) of 55:45 and 45:55; and 2) corn silage particle lengths of 9.52 and 19.05 mm. All experimental cows received 1 kg of flaxseed to substitute for 1 kg of a rolled barley grain-based concentrate daily. Diets were fed twice daily as a total mixed ration. Corn silage particle length and F:C ratio had no effect on dry matter intake, milk yield, and milk composition; however, feeding short cut corn silage depressed milk protein yield. Significant particle size × F:C ratio interactions were observed for milk fat proportions of C_16:0, C_18:1cis-9, and C_18:2cis-9, trans-11 (a conjugated linoleic acid isomer). At short corn silage particle size, decreasing F:C ratio depressed milk fat proportion of C_16:0. Conversely, feeding short corn silage at high F:C ratio increased the proportion of C_18:1cis-9 and C_18:2cis-9, trans-11 in milk fat. The milk fat proportion of C_18:2trans-10, cis-12, a conjugated linoleic acid isomer that is associated with milk fat depression, was not affected by dietary treatment. Our results show that corn silage particle length and F:C ratio influence milk fatty acid profiles in dairy cows fed supplemental flaxseed as a source of polyunsaturated fatty acids.     

Fatty acid composition and oxidative stability of oils recovered from acid silage and bacterial fermentation of fish (Sea bass – Dicentrarchus labrax) by‐products

Lipid quality and fatty acid compositions of fish oils recovered from fish (Sea bass – Dicentrarchus labrax) waste silages produced with formic acid (FA) and five different LAB strains (Lactobacillus plantarum (LP), Pediococcus acidilactici (PA), Enterococcus gallinarum (EG), Lactobacillus brevis (LB) and Streptococcus spp. (ST)) were assessed to ensure for the usage for human consumption. Generally, it was observed that there were no significant differences between PUFA contents (23.27–23.64%). Peroxide (PV) (2.12 meq active O₂/per kg of oil) and TBA values (1.07 mg malonaldehyde (MA) g^?1 oil) of fish oils from acid silage were significantly higher than those of the fermented ones (1.14–1.91 meq active O₂ kg^?1, 0.67–0.81 mgMA g^?1 oil, respectively). Anisidine values (AV) were determined in range of 8.04–11.14 for fermented silages and 13.08 from acid silage. The highest totox value (17.33 ± 0.88) was also detected in acid silage oil whereas fermented groups gave totox value in the range of 10.40–13.88. It can be concluded that the initial lipid quality of fermented fish waste silages was better than the initial lipid quality of acid fish waste silage. Therefore, fish oils recovered from fermented silages can be used as food additives or supplements for animal and human diets.     

Comparative potential of white and red clover to modify the milk fatty acid profile of cows fed ryegrass‐based diets from zero‐grazing and silage systems

BACKGROUND: Two experiments were conducted to compare the effects of white and red clover on the fatty acid composition of milk fat from cows fed ryegrass‐based diets. In experiment 1, fresh ryegrass was mixed with white or red clover (60/40, on a dry matter (DM) basis). Experiment 2 involved similar mixed diets in ensiled form, and one ryegrass‐silage diet without the addition of clover. RESULTS: Total DM intake, milk yield and milk fat content were not affected by dietary treatments. Feeding freshly cut white versus red clover supplemented diets resulted in a higher proportion of n‐3 fatty acids, especially α‐linolenic acid, in milk fat. Addition of any clover silage to ryegrass silage increased the proportions of n‐3 fatty acids in milk fat, and reduced the proportions of conjugated linoleic acids (CLA), including C18:2 c9t11, and C18:1cis isomers. The n‐6/n‐3 ratio was elevated compared to the diet not supplemented with clover. CONCLUSION: White clover seemed to be slightly superior to red clover supplementation, but the effects of clover supplementation as such were generally larger than that of clover type. However, a higher concentration of n‐3 fatty acids with clover supplementation coincided with a lower concentration of CLA in the milk fat. Copyright © 2007 Society of Chemical Industry     

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.     

The effect of decanoic,dodecanoic and tetradecanoic acids on silage fermentation

The ability of decanoic (C₁₀), dodecanoic (C₁₂) and tetradecanoic (C₁₄) acids to restrict the fermentation of ryegrass and lucerne was investigated with laboratory silos. With ryegrass, addition of the C₁₂ acid alone at 1 kg t^?1 of fresh crop had no effect on extent or pattern of fermentation compared to that of the untreated crop, though at 2 kg t^?1 the acid appeared to reduce the content of butyric acid but not ammonia-N in the silage. Formic acid, added alone or with C₁₀, C₁₂ and C₁₄ acids restricted extent of fermentation and butyric acid production, but in this experiment addition of these acids had relatively little effect on the content of ammonia-N in the silages. With lucerne, extent of fermentation was similar for all treatments, though the untreated silage and those which received C₁₂ or formic acid alone at 1 kg t^?1 or 1 kg t^?1 of C₁₄ acid with 1 kg t^?1 of formic acid contained butyric acid in excess of 3% of the dry matter (DM). It is concluded that acids in the range C₁₂-C₁₄ are not effective in restricting silage fermentation and that their effectiveness is not increased by reduction in pH produced by the addition of formic acid. Microbiological assessments largely confirmed these findings.     

Effects of forage type, forage to concentrate ratio, and crushed linseed supplementation on milk fatty acid profile in lactating dairy cows

The effects of an increasing proportion of crushed linseed (CL) in combination with varying forage type (grass or corn silage) and forage to concentrate ratio (F:C), and their interactions on milk fatty acid (FA) profile of high-producing dairy cows was studied using a 3-factor Box-Behnken design. Sixteen Holstein and 20 Swedish Red cows were blocked according to breed, parity, and milk yield, and randomly assigned to 4 groups. Groups were fed different treatment diets formulated from combinations of the 3 main factors each containing 3 levels. Forage type (fraction of total forage dry matter, DM) included 20, 50, and 80% grass silage, with the remainder being corn silage. The F:C (DM basis) were 35:65, 50:50, and 65:35, and CL was supplied at 1, 3, and 5% of diet DM. Starch and neutral detergent fiber content (DM basis) of the treatment diets ranged from 117 to 209 g/kg and 311 to 388 g/kg, respectively. Thirteen treatment diets were formulated according to the Box-Behnken design. During 4 experimental periods of 21 d each, all treatment diets were fed, including a repetition of the center point treatment (50% grass silage, 50:50 F:C, 3% CL) during every period. Intake, production performance, and milk FA profile were measured, and response surface equations were derived for these variables. Shifting from 80% grass silage to 80% corn silage in the diet linearly increased dry matter intake (DMI), net energy for lactation (NE_L) intake, cis-9,cis-12-C18:2 (C18:2n-6) intake, and milk yield, and linearly decreased cis-9,cis-12,cis-15-C18:3 (C18:3n-3) intake and milk fat content. Shifting from a high forage to a high concentrate diet linearly increased DMI, NE_L intake, C18:2n-6 intake, and milk yield, and decreased milk fat content. Supplementation of CL linearly increased C18:3n-3 intake, but had no effect on DMI, NE_L intake, milk yield, or milk fat content. Shifting from 80% grass silage to 80% corn silage linearly increased proportions of trans-10-C18:1 and C18:2n-6 in milk fat, whereas the proportions of trans-11,cis-15-C18:2 and C18:3n-3 linearly decreased. Significant interactions between CL supplementation and F:C were found for proportions of trans-10-C18:1, trans-15-C18:1, cis-15-C18:1, trans-11,cis-15-C18:2, and C18:3n-3 in milk fat, with the highest levels achieved when the diet contained 5% CL and a 35:65 F:C ratio. The effect of supplementing CL on several milk FA proportions, including C18:2n-6 and C18:3n-3, depends significantly on the F:C ratio and forage type in the basal diet.     

The influence of hydrochloric acid on the effect of caproic acid in preventing aerobic deterioration of silages

In five experiments of the same design using silages made from wilted Italian ryegrass (dry matter 22.7–40.9%), the effects of caproic acid (C₆) (10 mmol kg^?1) with and without 6_N-HCl (20 ml kg^?1), applied at ensiling or at opening, in preventing aerobic deterioration of silages after opening silos were investigated. Application of C₆ either at ensiling or at opening was partially effective in preventing temperature increase, pH rise and breakdown of organic acids during the 7-day aerobic exposure period after opening the silos. Addition of HCl reduced the pH of silages irrespective of the time of application. However, no improvement of the effect of C₆ due to HCl supplementation was observed as far as the prevention of the aerobic deterioration was concerned. Treatment with C₆+ HCl at ensiling inhibited silage fermentation more extensively than C₆ alone. Viable counts of yeasts and moulds in the silages treated with C₆ or C₆+ HCl at ensiling tended to be lower than those in the control silages. Considerable increases in the counts of moulds were found in the control silages during the aerobic exposure period.     

Effects of extraction and reconstitution of ryegrass juice on fermentation,digestion and in situ degradation of pressed cake silage

Primary growth of Italian ryegrass was fractionated into green juice and pressed cake (PC). PC was ensiled either directly or after reconstitution with the juice which was spray dried and then added to water before ensiling (RPC). This process was aimed at distinguishing between chemical (removal of nutrients) and physical (mechanical disintegration) effects of fractionation. Two additional wilted silages were prepared from long cut or chopped Italian ryegrass (WL and WC, respectively). The fermentative quality, digestion and in situ degradation of dry matter for the four silages were compared. WC, RPC and PC silages indicated lactate-rich fermentation while WL silage had a comparatively low lactate content. PC silage had a lower (P<0·05) pH value with lower (P<0·05) amounts of organic acids compared with WC and RPC silage, suggesting that removal of buffering components with the juice had greater effects than shredding on fermentation of PC silage. The digestibility of protein was lower (P<0·05) in PC than WL silage but the reduction was compensated for in RPC silage. Ruminal concentrations of total volatile fatty acids were the highest (P<0·05) when goats fed WL silage while those on the other silages had similar concentrations. Ruminal pH was lower (P<0·05) in goats fed PC than WC silage and the difference was not fully reversed by reconstituting the juice to PC. Juice extraction decreased (P<0·05) the soluble fraction and the rate of disappearance of dry matter in the rumen but the potential degradability was not different among treatments. These results suggest that both chemical and physical changes due to the fractionation affect the characteristics of digestion of PC silage while the removal of nutrients has a major role in the modified silage fermentation. © 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     

Characteristics of lactic acid bacteria isolated from forage crops and their effects on silage fermentation

Enterococcus faecalis CA 6, E faecium CA 10, E casseliflavus CA 13, Weissella paramesenteroides CA 14, Leuconostoc pseudomesenteroides CA 17, Pediococcus pentosaceus CA 21, P acidilactici CA 25 and Lactobacilus plantarum CA 28 isolated from forage crops were characterised and their effects on silage fermentation were studied. Strains CA 6, CA 10 and CA 13 grew only at relatively high pH (above 5.0), while strains CA 21, CA 25 and CA 28 were able to grow at pH values below 4.0. Strain CA 25 grew at 50 °C, but the others did not grow at above 45 °C. These strains were used as inoculants for perennial ryegrass silage ensiled at 25 or 45 °C. At 25 °C all strains significantly (P < 0.01) reduced the pH value and butyric acid content and greatly increased the lactic acid content compared with the control, particularly strains CA 21, CA 25 and CA 28. At 45 °C strain CA 25 markedly improved the fermentation quality of silage, but the others did not. These silages had a lower lactic acid content and a higher proportion of L (+)‐ to total lactic acid than equivalent silages kept at 25 °C. The results confirmed that at 25 °C P pentosaceus CA 21, P acidilactici CA 25 and L plantarum CA 28 were the most effective, whereas at 45 °C only P acidilactici CA 25 had a beneficial effect on silage fermentation quality. © 2000 Society of Chemical Industry     

Resistance to aerobic deterioration of total mixed ration silage inoculated with and without homofermentative or heterofermentative lactic acid bacteria

Wet brewers grains were stored as a total mixed ration (TMR) in laboratory silos with lucerne hay, cracked maize, sugar beet pulp, soya bean meal and molasses at 5:1:1:1:1:1 on fresh weight basis. The TMR mixture was inoculated with or without Lactobacillus casei or Lactobacillus buchneri to obtain silages with differing fermentation and stability after exposure to air. In the first experiment, ensiling was stopped at 10, 20 and 60 days, and the stability was tested for the following 7 days. Ethanol and lactic acid were the main products in untreated TMR silage, while addition of L. casei and L. buchneri increased lactic and acetic acid, respectively. No silages deteriorated in the presence of air over 7 days, regardless of inoculation, ensiling period and the level of yeasts determined at unloading. In the second experiment, silos were opened at 14 days and then subjected to aerobic stability test for 14 days. Resistance to deterioration was sustained in the untreated control, even with a high population (>10⁴ cfu g^?1) of yeasts throughout the 14‐day test. Spoilage was found in L. casei‐treated silage at about 5 days, while increase of yeasts preceded the distinct heating (degradation). In L. buchneri‐treated silage, no yeasts were detected at unloading or after exposure to air. These results suggest that substantial stability can be expected in TMR silage with or without inoculation of lactic acid bacteria. This property is not associated with the counts of yeasts at loading and the characteristics of silage such as alcoholic and lactic acid fermentation. Copyright © 2007 Society of Chemical Industry     

Inclusion of wheat and triticale silage in the diet of lactating dairy cows

The objective of this experiment was to partially replace corn silage with 2 alternative forages, wheat (Triticum aestivum) or triticale (X Triticosecale) silages at 10% of the diet dry matter (DM), and investigate the effects on dairy cow productivity, nutrient utilization, enteric CH₄ emissions, and farm income over feed costs. Wheat and triticale were planted in the fall as cover crops and harvested in the spring at the boot stage. Neutral- and acid-detergent fiber and lignin concentrations were higher in the wheat and triticale silages compared with corn silage. The forages had similar ruminal in situ effective degradability of DM. Both alternative forages had 1% starch or less compared with the approximately 35% starch in corn silage. Diets with the alternative forages were fed in a replicated 3 × 3 Latin square design experiment with three 28-d periods and 12 Holstein cows. The control diet contained 44% (DM basis) corn silage. In the other 2 diets, wheat or triticale silages were included at 10% of dietary DM, replacing corn silage. Dry matter intake was not affected by diet, but both wheat and triticale silage decreased yield of milk (41.4 and 41.2 vs. 42.7 ± 5.18 kg/d) and milk components, compared with corn silage. Milk fat from cows fed the alternative forage diets contained higher concentrations of 4:0, 6:0, and 18:0 and tended to have lower concentrations of total trans fatty acids. Apparent total-tract digestibility of DM and organic matter was decreased in the wheat silage diet, and digestibility of neutral-and acid-detergent fiber was increased in the triticale silage diet. The wheat and triticale silage diets resulted in higher excretion of urinary urea, higher milk urea N, and lower milk N efficiency compared with the corn silage diet. Enteric CH₄ emission per kilogram of energy-corrected milk was highest in the triticale silage diet, whereas CO₂ emission was decreased by both wheat and triticale silage. This study showed that, at milk production of around 42 kg/d, wheat silage and triticale silage can partially replace corn silage DM and not affect DM intake, but milk yield may decrease slightly. For dairy farms in need of more forage, triticale or wheat double cropped with corn silage may be an appropriate cropping strategy.     

Minimizing the level of butyric acid bacteria spores in farm tank milk

A year-long survey of 24 dairy farms was conducted to determine the effects of farm management on the concentrations of butyric acid bacteria (BAB) spores in farm tank milk (FTM). The results were used to validate a control strategy derived from model simulations. The BAB spore concentrations were measured in samples of FTM, feces, bedding material, mixed corn and grass silage fed to cows in the barn, and soil. In addition, a questionnaire was used to gather farm management information such as bedding material used and teat cleaning method applied. The average BAB spore concentration in FTM was 2.7 log₁₀ spores/L, and 33% of the FTM samples exceeded a concentration of 3 log₁₀ spores/L. Control of the average spore concentration in mixed silage fed was the only aspect of farm management that was significantly related to the concentration of BAB spores in FTM. Farms that fed mixed silage with the lowest average BAB spore concentrations (3.4 log₁₀ spores/g) produced FTM with the lowest average concentration (2.1 log₁₀ spores/L). The efficiency of farm management in controlling the BAB spore concentration in FTM depended to a large extent on the ability of farmers to prevent incidents with elevated BAB spore concentrations in mixed silage (>5 log₁₀ spores/g) and not on the average BAB spore concentration in mixed silage across the year. The survey showed that farmers should aim for a concentration in mixed silage of less than 3 log₁₀ spores/g and should prevent the concentration from exceeding 5 log₁₀ spores/g to ensure a concentration in FTM of less than 3 log₁₀ spores/L. These results correspond with the previously reported model simulations.     

Concentrations of butyric acid bacteria spores in silage and relationships with aerobic deterioration

Germination and growth of spores of butyric acid bacteria (BAB) may cause severe defects in semihard cheeses. Silage is the main source of BAB spores in cheese milk. The objectives of the study were to determine the significance of grass silages and corn silages as sources of BAB spores and to investigate the relationships between high concentrations of BAB spores in corn silage and aerobic deterioration. In the first survey, samples were taken from various locations in silos containing grass and corn silages and from mixed silages in the ration offered to the cows on 21 farms. We demonstrated that the quantity of BAB spores consumed by cows was determined by a small fraction of silage with a high concentration of spores (above 5 log₁₀ BAB/g). High concentrations were most often found in corn silage within areas with visible molds (69% of the samples). Areas with visible molds in grass silage and surface layers of corn silage contained, respectively, 21 and 19% of the cases of concentrations above 5 log₁₀ BAB spores/g. Based on these results, we concluded that currently in the Netherlands, corn silage is a more important source of BAB than is grass silage. In a second survey, 8 corn silages were divided into 16 sections and each section was studied in detail. High concentrations of BAB spores were found in only the top 50 cm of these 8 silages. Elevated concentrations of BAB spores were associated with different signs of aerobic deterioration. In 13% of the sections in corn silage with more than 5 log₁₀ yeasts and molds/g, more than 5 log₁₀ BAB spores/g were found. Sections with a temperature of more than 5°C above ambient temperature contained, in 21% of the cases, more than 5 log₁₀ BAB spores/g. Concentrations above 5 log₁₀ BAB spores/g were measured in 50% of the sections with a pH above 4.4. All sections with a pH above 4.4 also showed a temperature that was more than 5°C above ambient temperature and a concentration of yeasts and molds above 5 log₁₀ cfu/g. Based on these results, we postulated that high concentrations of BAB spores in corn silage are the result of oxygen penetration into the silage, resulting in aerobic deterioration and the formation of anaerobic niches with an increased pH just below the surface. Growth of BAB in these anaerobic niches with an increased pH caused the locally high concentrations of BAB in corn silage.     

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     

Protein nutrition of dairy cows receiving grass silage diets: Effects of feeding a protein supplement of unbalanced amino acid composition

Eight cows were used in a replicated 4 × 4 latin square design experiment with period lengths of 3 weeks to investigate the effects of protein supplementation of a grass silage diet on silage intake and milk production. The four treatments were (i) the basal diet, consisting of grass silage ad libitum plus 2 kg day^?1 of molassed sugar beet pulp; (ii) basal diet plus 1 kg day^?1 of fish meal (F): (iii) basal diet plus 0.8 kg day^?1 of feather meal 1 (FE1); and (iv) basal diet plus 0.8 kg day^?1 of feather meal 2 (FE2). Silage intake was significantly (P < 0.01) increased by the F supplement but was not affected by the FE supplements; values were 9.9, 10.6, 9.6 and 9.6 kg DM day^?1 for basal, F, FE1 and FE2, respectively. Relative to the basal treatment, F increased (P < 0.001) the yield of milk and milk protein but, again, these were unaffected by FE; values were, for milk yield, 13.6, 16.3, 13.7 and 13.1 kg day^?1; and, for milk protein yield, 420, 545, 429 and 414 g day^?1 for basal, F, FE1 and FE2, respectively. However, supplementation with FE produced increases in the concentration (P < 0.001) and yield (P < 0.05) of milk fat; values were 42.8, 39.9, 46.6 and 47.8 g kg^?1 and 575, 646, 628 and 618 g day^?1 respectively, for the basal, F, FE1 and FE2 treatments. The profile of amino acids in blood plasma was characterised by markedly lower (at least P < 0.01) concentrations of methionine, lysine, tryptophan and histidine for the diets containing FE compared with F. The results show pronounced effects of the amino acid composition of the undegraded protein component of the supplement on both silage intake and milk production but also draw attention to a possible relationship between amino balance and the secretion of milk fat.     

Low permeability to oxygen of a new barrier film prevents butyric acid bacteria spore formation in farm corn silage

The outgrowth of Clostridium spore-forming bacteria causes late blowing in cheeses. Recently, the role of air diffusion during storage and feed-out and the role of aerobic deterioration has been shown to indirectly favor butyric acid bacteria (BAB) growth and to determine the presence of high concentrations of BAB spores in farm tank milk. A new oxygen barrier (OB) film was tested and compared with conventional polyethylene (ST). The objective was to verify whether the OB film could prevent BAB spore formation in whole-crop corn silage during storage on 2 commercial farms with different potential silage spoilage risks. Two bunkers (farms 1 and 2) were divided into 2 parts along the length so that half the feed-out face would be covered with ST film and the other half with OB film. Plastic net bags with freshly chopped corn were buried in the upper layer and in the central part (CORE) of the bunkers. The silos were opened in summer and fed out at different removal rates (19 vs. 33 cm/d). Herbage at ensiling, silage at unloading, and silage after air exposure (6 and 15 d) were analyzed for pH, nitrate, BAB spores, yeasts, and molds. The BAB spores in herbages at ensiling were 2.84 log₁₀ most probable number (MPN)/g, with no differences between treatments or farms. Nitrate was below the detection limit on farm 1 and exceeded 2,300 mg/kg of fresh matter on farm 2. At unloading, the BAB spores in the ST silage on farm 1 were greater than 5 log₁₀ MPN/g, whereas in the CORE and the OB silages, they were approximately 2 log₁₀ MPN/g. The ST silage had the greatest pH (5.89), the greatest mold count (5.07 log₁₀ cfu/g), and the greatest difference between silage temperature and ambient temperature (dT_{section-ambient}). On farm 2, the ST silage had the greatest concentration of BAB spores (2.19 log₁₀ MPN/g), the greatest pH (4.05), and the least nitrate concentration compared with the CORE and the OB silages. Pooled data on BAB spores collected from aerobically deteriorated samples showed a positive relationship with pH, mold count, and dT_{section-ambient} and a negative relationship with nitrate concentration. A high concentration of BAB spores (>5 log MPN/g) was associated with visible spoilage, high pH values (>5.00), high mold counts (>5 log cfu/g), high dT_{section-ambient}, and nitrate below 1,000 mg/kg of fresh matter. We concluded that the use of a film with reduced oxygen permeability prevented the outgrowth of BAB spores during conservation and feed-out, and it could improve the microbiological quality of corn silage by eliminating the fractions of silage with high BAB spore concentrations.