Whole-crop Maize Research Articles

Effect of type of roughage on chemical composition and technological value of milk from cows fed TMR diets

AbstractAn experiment was conducted to determine the degree to which feeding Polish Black-and-White Holstein-Friesian cows with total mixed rations (TMR) differing in the type of “energy” roughages (whole-crop maize silage, MS; winter barley silage, BS) and their proportion (70% or 50% in DM) relative to wilted meadow grass silage (GS) will affect the yield, chemical composition, fatty acid profile and technological suitability of milk, the quality traits and organoleptic score of some milk products (curd cheese, soft rennet cheese, creamery butter), and the fatty acid profile of butter fat. The study was carried out during the second trimester of lactation using 36 cows assigned to four analogous groups with 9 animals per group. It was found that replacing maize silage with barley silage in TMR diets had no significant effect on the yield, chemical composition, fatty acid content and technological suitability of milk, or on the content of major protein fractions and protein substances. Curd cheese and rennet cheese from the milk of cows fed diets with barley and wilted grass silages (groups BS/GS-I and BS/GS-II) and creamery butter from the milk of cows fed diets with a lower (50% DM) proportion of “energy” silages (MS/GS-II and BS/GS-II) were characterized by a higher (P≤0.01) content of solids and fat compared to analogous products from the milk of cows in the other groups (MS/GS-I and BS/GS-I). Butter from the milk of MS/GS-I and MS/GSII cows had a significantly higher content of PUFA (including C18:2 n-6, C18:3 n-6, C18:3 n-3 and CLA), and a lower content of SFA (from C-4 to C-16) compared to BS/GS-I and BS/GS-II cows. Regardless of the type of total mixed ration fed in the second trimester of lactation, the milk and milk products had desirable functional and technological properties.

Yield, nutritive value and ensilage characteristics of whole-crop maize, and of the separated cob and stover components – nitrogen, harvest date and cultivar effects

SUMMARYThe objectives of the present study were to determine the effects of nitrogen (N) application rate, harvest date and maize cultivar on the yield, quality and the subsequent conservation characteristics of whole-crop, cob and stover silages. The experiment was organized in a spilt-plot design, with harvest date (15 September, 6 October and 27 October) as the main plot, and a three (maize cultivars: Tassilo, Andante and KXA 7211)×two (N application rate: 33 and 168 kg N/ha) factorial arrangement of treatments as the sub-plot, within three replicate blocks, and was conducted at Grange, Dunsany, Co. Meath, Ireland in 2009. The three harvest dates represented early, normal and late harvests, respectively, for a midland site in Ireland. Of the three maize cultivars selected, cvars Tassilo and Andante represent conventional cultivars sown by commercial livestock farmers in Ireland, while cvar KXA 7211 is categorized as a high biomass cultivar. No effect of N application rate was observed on the dry matter (DM) yield, nutritive value or ensiling characteristics of maize whole-crop or cob. Whole-crop and stover harvested on the later date had a lower digestible DM (DDM) content and the silages underwent a more restricted fermentation, compared to silages produced from herbage harvested on earlier dates. Cob silages produced from crops harvested on 15 September had lower DDM content and higher DM loss during ensiling than later harvest dates. Despite higher whole-crop DM yields, the later maturing cultivar KXA 7211 did not improve the DM yields of cob and also resulted in increased DM losses from the ensilage of cob, when compared with the other cultivars. In addition to the DM yield and nutritive value of forage maize at harvest, the subsequent fermentation profile during ensilage influences the optimum choice of cultivar and date for crop harvest in a maize silage production system.

Effects of bacterial silage inoculants on whole-crop maize silage fermentation and silage digestibility in rams

This study evaluated the effects of ensiling whole-crop maize with bacterial inoculants, Lactococcus lactis (LL) and Lactobacillus buchneri (LB), on the fermentation and nutrient digestibility in rams. Whole-crop maize (265 DM g/kg) was ensiled for 90 days in 210 L drums with no additive, or with LL or LB. After three months, the drums were opened and the silage was sampled for fermentation characteristics. Diets were produced by mixing the whole-crop maize silage with lucerne hay (90 : 10) on an “as fed” basis, and a digestibility study was conducted using five South African Mutton Merino rams (37.2 ± 2.2 kg live weight) per treatment. Inoculating maize silage with LL and LB reduced ammonia nitrogen concentration, but did not affect silage pH. The concentration of lactic acid was increased with LL compared to the other treatments. A higher concentration of acetic acid was obtained with LB inoculation compared to the other treatments. The aerobic stability of the silage was improved with LB while it was reduced with LL inoculation, as indicated by a higher CO 2 production than the latter. The intake and digestibility of dry matter, organic matter, crude protein and fibre were improved by inoculation. Furthermore, inoculations resulted in improved nitrogen retention. It was concluded that the inoculants improved silage fermentation and diet digestibility. Inoculation with LB improved aerobic stability and LL inoculation reduced it. Keywords: Alfalfa, lucerne, aerobic stability, Lactococcus lactis , Lactobacillus buchneri

Effects of a dual-purpose bacterial inoculant on the fermentation characteristics of high-moisture maize silage and dairy cattle performance

The objective of this study was to investigate the effects of inoculating Lactisil Maize, a dual-purpose inoculant, on the fermentation characteristics and nutritive value of high-moisture maize silage and the performance of lactating cows receiving the silage in their diets. Whole-crop maize was harvested at 253 g dry matter (DM)/kg fresh crop. Maize silage was produced with or without Lactisil Maize and ensiled in two different bunkers. Eight multiparous lactating Holstein dairy cows were used in a replicated 2 × 2 Latin square experimental design and were fed total mixed rations that contained 230 g/kg of either inoculated or control maize silage. Inoculation did not affect the nutritive value or the aerobic stability of the maize silage, but increased the neutral detergent and acid detergent fibre fractions of the silage. However, inoculation increased the concentrations of acetic acid and lactic acid, but reduced ammonia N concentration compared to the control. Cows fed the Lactisil Maize-inoculated silage had a lower DM intake, milk yield, and yields of milk fat and milk protein were lower, compared to control. The digestibility of nutrients was not affected by inoculation. It was concluded that although Lactisil Maize inoculation improved the fermentation quality of high-moisture maize silage, it did not improve aerobic stability of the silage or the production performance of dairy cows compared to the control.

Performance of finishing beef cattle fed different diets containing whole-crop maize silage or sugarcane silage

The objective of the present study was to evaluate the performance of beef cattle in feedlots fed diets containing either whole-crop maize silage or sugarcane silage, and with different formulations. Five diets were evaluated: MSF - diet containing whole-crop maize silage, with fixed formulation during feedlot period; MSV- diet containing whole-crop maize silage, with variable formulation according to feedlot phase; SCSF - diet containing sugarcane silage with fixed formulation; SCSV- diet containing sugarcane silage, with variable formulation; SCSV/MSV- SCSV diet in initial half of fedlot and MSV diet in final half of feedlot period, respectively. It was used a complete random experimental design, with five treatments and three replicates (pens). It was used 285 steers at 36 months of age, with an initial body weight of 362.4 kg. Diets with whole-crop maize silage promoted greater intake of dry matter (10.5 kg and 2.4% BW) compared with diets containing sugarcane silage (10.1 kg and 2.3% BW). There was no effect of the silages on average daily gain (1.348 kg/animal/day) and live weight at slaughter (481.2 kg BW). SCSV/MSV diet promoted the worst feed conversion (8.0 kg DM/kg BW). Animals fed diets composed of whole-crop maize silage presented greater weight of hot carcass, of carcass yield and subcutaneous fat thickness (262.1 kg, 54.1% and 6.2 mm) compared with the animals fed sugarcane silage (252.5 kg, 52.7% and 4.8 mm). The use of sugarcane silage in diets for finishing beef cattle is feasible and the adjustment of formulation during confinement period does not influence performance of the animals. Replacement of sugarcane silage by whole-crop maize silage during the feeding period affects negatively feed conversion.

Effects of inoculation with lactic acid bacteria on the bacterial communities of Italian ryegrass, whole crop maize, guinea grass and rhodes grass silages

Italian ryegrass (IR), whole crop maize (WM), guinea grass (GG) and rhodes grass (RG) were stored in laboratory silos for 30 d with and without Lactobacillus plantarum or Lactobacillus brevis inoculation. The grasses were wilted to low moisture levels (about 500 g/kg) prior to ensiling, while WM was ensiled directly after harvest. Microbial counts and bacterial community analyses were undertaken by plate-culture and denaturing gradient gel electrophoresis (DGGE), respectively, on pre- and post-ensiled crops. A total of 31 DGGE bands were retrieved, cloned, and sequenced to identify bacterial species according to their 16S rRNA gene sequences. Inoculation with L. plantarum and L. brevis increased (P<0.05) lactic acid and decreased (P<0.05) 2,3-butanediol contents in wilted grass silages, with higher (P<0.05) contents of lactic acid observed in L. plantarum-inoculated silages compared to L. brevis-inoculated silages. Inoculation with L. brevis increased (P<0.05) both lactic and acetic acid contents in IR silage and intensified lactic acid production in GG and RG silages. Inoculation with either L. plantarum or L. brevis did not affect fermentation of WM silage, except that the lactic acid to acetic acid ratio increased (P<0.05) in L. plantarum-inoculated silage. Differences in inoculation effects could be accounted for by changes in bacterial communities present in the silages. Interestingly, in wilted grass silages, the inoculation nearly eliminated the indigenous communities, leaving the inoculated species as the principal bacteria. In maize silage, desirable bacterial communities were found in untreated control, and the inoculated lactic acid bacteria (LAB) were additive to the uninoculated communities. Combination of fermentation product analysis and bacterial community analysis may describe the effects of LAB inoculation on the ensiling process.

Pretreatment of Whole-Crop Harvested, Ensiled Maize for Ethanol Production

To have all-year-round available feedstock, whole-crop maize is harvested premature, when it still contains enough moisture for the anaerobic ensiling process. Silage preparation is a well-known procedure for preserving plant material. At first, this method was applied to obtain high-quality animal feed. However, it was found that such ensiled crops are very suitable for bioenergy production. Maize silage, which consists of hardly degradable lignocellulosic material, hemicellulosic material, and starch, was evaluated for its potential as a feedstock in the production of bioethanol. It was pretreated at low severity (185 degrees C, 15 min) giving very high glucan ( approximately 100%) and hemicellulose recoveries (<80%)-as well as very high ethanol yield in simultaneous saccharification and fermentation experiments (98% of the theoretical production based on available glucan in the medium). The theoretical ethanol production of maize silage pretreated at 185 degrees C for 15 min without oxygen or catalyst was 392 kg ethanol per ton of dry maize silage.

The effect of Lactobacillus buchneri on the fermentation, aerobic stability and ruminal degradability of maize silage

To evaluate the effect of Lactobacillus buchneri, heterofermentative lactic acid bacteria (LAB), on the fermentation, aerobic stability and ruminal degradability of whole-crop maize silages under laboratory conditions. Two homofermentative LAB were tested for the purpose of comparison. Maize was harvested at early dent [290 g kg(-1) dry matter (DM)] and one-half milk line (355 g kg(-1) DM) stages. Both homofermentative LAB were applied at 1 x 10(5) CFU g(-1) of fresh forage. Lactobacillus buchneri was applied at 1 x 10(5), 5 x 10(5) and 1 x 10(6) CFU g(-1) of fresh forage. Silages with no additives served as control. After treatment, the chopped forages were ensiled in 1.5-l anaerobic jars. Three jars per treatment were sampled on day 60. After 60 days of storage, silages were subjected to an aerobic stability test lasting for 5 days, in which CO(2) production, as well as chemical and microbiological parameters, was measured to determine the extent of aerobic deterioration. Both homofermentative LAB increased the concentration of lactic acid and the numbers of yeasts, and decreased the concentration of acetic acid and impaired the aerobic stability of silages. In contrast, applying L. buchneri decreased the concentration of lactic acid and increased the concentration of acetic acid of the silages. Under aerobic conditions, silages treated with 5 x 10(5) and 1 x 10(6) CFU g(-1) of L. buchneri, had lower pH, CO(2) production and the numbers of yeasts than the silages treated with 1 x 10(5) CFU g(-1) of L. buchneri (P < 0.05). However, all doses of L. buchneri and both homofermentative LAB did not affect in situ rumen DM, organic matter and neutral detergent fibre degradability of the silages. Lactobacillus buchneri was very effective in protecting maize silages exposed to air under laboratory conditions. All doses of L. buchneri, especially 5 x 10(5) CFU g(-1) or more, markedly decreased the numbers of yeasts and improved the aerobic stability of silages. The use of L. buchneri, as a silage inoculant, can improve the aerobic stability of maize silages by inhibition of yeast activity.

Effects of Ensiling Alfalfa with Whole-crop Maize on the Chemical Composition and Nutritive Value of Silage Mixtures

The aim of this study was to evaluate the chemical composition, in vitro DM degradability, ME and OMD of alfalfa- maize silage mixtures in comparison to pure maize and alfalfa silages, and to test the existence of associative effects of ensiling alfalfa forage with whole-crop maize using the in vitro gas production technique. Ensiling alfalfa with whole-crop maize had a significant (p<0.001) effect on chemical composition, pH, in vitro DM degradability, OMD and estimated ME values of mixtures. DM content of the resultant silages significantly increased with increasing proportion of whole-crop maize in the mixtures, whereas the pH value, crude protein (CP), acid detergent fibre (ADF) and ash contents of mixtures decreased due to the dilution effect of whole-crop maize which was low in CP, ADF and ash. The pH values of all alfalfa-maize silage mixtures were at the desired level for quality silage. Gas production of alfalfa-maize silage mixtures at all incubation times except 12 h increased with increasing proportion of whole-crop maize. When alfalfa was mixed with whole-crop maize in the ratio 40:60, ME and OMD values were significantly (p<0.001) higher than other silages. Maximum gas production (Agas) ranged from 65.7 to 78.1 with alfalfa silage showing the lowest maximum gas production. The results obtained in this study clearly showed that maximum gas production increased with increased percentage of whole-crop maize in the silage mixtures (r = 0.940, p<0.001). It was concluded that ensiling alfalfa with whole-crop maize improved the pH, OMD and ME values. However, trials with animals are required to see how these differences in silage mixtures affect animal performance. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 4 : 526-532)

Biomass production and allocation in rice with implications for straw harvesting and utilization : Summers, M. D. et al. Biomass and Bioenergy, 2003, 24, (3), 163–173

The aim of this study was to examine the effects and possible interactions between forage particle size and intake level on the site and extent of digestion and on ruminal fermentations in dairy cows fed mixed diets. Two forage particle sizes (chopped [C] or ground and pelleted alfalfa [G]) and two intake levels (ad libitum [H] and 80% of ad libitum [L]) were combined in a 2×2 factorial arrangement. Four mid-lactating cows equipped with ruminal and duodenal cannulas were used in a 4×4 Latin square design. On a dry matter (DM) basis, the four diets consisted of 18% maize silage, 25% dehydrated pelleted whole-crop maize, 25% dehydrated alfalfa and 32% concentrate. They were distributed twice daily with three hours access after each distribution. Dry matter intake averaged 21.9 kg day−1 for the H level. Feeding G rather than C diets reduced chewing time (22.1 vs. 27.7 min kg−1 DM). Feeding G diets sharply reduced organic matter (OM) and cell-wall constituents digestibilities (P<0.01) with these effects being greater at H than at L intake (P<0.10). Starch digestibility and the site of digestion of OM and carbohydrate were unaffected, but non ammonia nitrogen flow into the duodenum was increased (P<0.05). Feeding G diets did not affect ruminal fermentation at the L intake level but the molar proportion of acetic acid was decreased and that of propionic acid was increased at the H intake level. When feeding GH diet, these changes in ruminal digestibility and fermentation patterns were associated with a reduced rumen retention time and lower cellulolytic activity which, in turn, were related to modifications in the ruminal environment. The range of pH during the day and hours below 5.6 were increased, whereas ruminal NH3 was decreased compared to the three others diets. When cows were fed at H level the digestibilities of OM and cell-wall constituents were depressed (P<0.01), along with the percentage of digestible materials disappeared in the rumen. Efficiency of microbial synthesis remained unaffected but the ruminal degradability of feed nitrogen tended to be lowered (P<0.10). The H level increased ruminal content but did not change ruminal retention time. Lower ruminal digestibilities were mainly related to a depressed rate of digestion at H level. It is concluded that reducing the forage particle size can strongly affect the quantity and the nature of the digestive end-products by altering ruminal conditions. However, the magnitude of these digestive effects is dependent on the amount of fermentable OM ingested.

Acetic Acid Increases Stability of Silage under Aerobic Conditions

The effects of various compounds on the aerobic stability of silages were evaluated. It has been observed that inoculation of whole-crop maize with homofermentative lactic acid bacteria leads to silages which have low stability against aerobic deterioration, while inoculation with heterofermentative lactic acid bacteria, such as Lactobacillus brevis or Lactobacillus buchneri, increases stability. Acetic acid has been proven to be the sole substance responsible for the increased aerobic stability, and this acid acts as an inhibitor of spoilage organisms. Therefore, stability increases exponentially with acetic acid concentration. Only butyric acid has a similar effect. Other compounds, like lactic acid, 1,2-propanediol, and 1-propanol, have been shown to have no effect, while fructose and mannitol reduce stability.

Effect of forage particle size and feeding frequency on fermentation patterns and sites and extent of digestion in dairy cows fed mixed diets

This trial aimed at studying the effects and possible interactions between forage particle size and feeding frequency on the site and extent of digestion and ruminal fermentations throughout the day in dairy cows fed mixed diets. Two forage particle sizes (chopped, C, or ground and pelleted, G, dehydrated alfalfa) and two feeding frequencies (two (2) or six (6) times daily) were combined in a 2×2! arrangement. Four mid-lactation cows with cannulae in the rumen and proximal duodenum were used in a 4×4 Latin square design. They were fed at 95% of ad-libitum intake with three hours access to the manger after each meal distribution. On a dry-matter (DM) basis, the four diets consisted of 40% dehydrated whole-crop maize, 4% long perennial ryegrass hay, 25% dehydrated alfalfa and 31% concentrate (69% wheat). Dry-matter intake averaged 22.2 kg day −1. No interaction between forage particle size and feeding frequency was found. Feeding G rather than C diets reduced chewing time (22.4 vs. 26.2 min kg −1 DM), total and ruminal digestibilities of organic matter (OM) and cell-wall constituents ( p<0.10), and increased the non-ammonia nitrogen flow into the duodenum per unit of digestible OM intake ( p<0.05). Feeding G diets also reduced the molar proportion of acetic acid and increased the molar proportions of propionic and valeric acids. These changes in ruminal digestion were associated with a lower fibrolytic activity and modifications in ruminal environment. The daily means of pH and ammonia concentration were decreased, while the range of pH during the day and the time when pH and ammonia concentration were low (<6.0 and 2.9 mmol l −1, respectively) were increased. At the same time, the proportion of fluid in the reticular contents and the fractional outflow rate of liquids and small particles were decreased. Increasing feeding frequency did not affect carbohydrate digestion and mean ruminal parameters, although post-feeding variations of pH, osmolality and ammonia concentration were much less pronounced. It is concluded that reduced forage particle size can sharply affect the quantity and the nature of digestive end-products by altering chemical and physical conditions in the rumen. However, the magnitude of this effect is not dependent on the amount of fermentable OM entering the rumen in one meal.

Effect of forage particle size and intake level on fermentation patterns and sites and extent of digestion in dairy cows fed mixed diets

The aim of this study was to examine the effects and possible interactions between forage particle size and intake level on the site and extent of digestion and on ruminal fermentations in dairy cows fed mixed diets. Two forage particle sizes (chopped [C] or ground and pelleted alfalfa [G]) and two intake levels (ad libitum [H] and 80% of ad libitum [L]) were combined in a 2×2 factorial arrangement. Four mid-lactating cows equipped with ruminal and duodenal cannulas were used in a 4×4 Latin square design. On a dry matter (DM) basis, the four diets consisted of 18% maize silage, 25% dehydrated pelleted whole-crop maize, 25% dehydrated alfalfa and 32% concentrate. They were distributed twice daily with three hours access after each distribution. Dry matter intake averaged 21.9 kg day −1 for the H level. Feeding G rather than C diets reduced chewing time (22.1 vs. 27.7 min kg −1 DM). Feeding G diets sharply reduced organic matter (OM) and cell-wall constituents digestibilities ( P<0.01) with these effects being greater at H than at L intake ( P<0.10). Starch digestibility and the site of digestion of OM and carbohydrate were unaffected, but non ammonia nitrogen flow into the duodenum was increased ( P<0.05). Feeding G diets did not affect ruminal fermentation at the L intake level but the molar proportion of acetic acid was decreased and that of propionic acid was increased at the H intake level. When feeding GH diet, these changes in ruminal digestibility and fermentation patterns were associated with a reduced rumen retention time and lower cellulolytic activity which, in turn, were related to modifications in the ruminal environment. The range of pH during the day and hours below 5.6 were increased, whereas ruminal NH 3 was decreased compared to the three others diets. When cows were fed at H level the digestibilities of OM and cell-wall constituents were depressed ( P<0.01), along with the percentage of digestible materials disappeared in the rumen. Efficiency of microbial synthesis remained unaffected but the ruminal degradability of feed nitrogen tended to be lowered ( P<0.10). The H level increased ruminal content but did not change ruminal retention time. Lower ruminal digestibilities were mainly related to a depressed rate of digestion at H level. It is concluded that reducing the forage particle size can strongly affect the quantity and the nature of the digestive end-products by altering ruminal conditions. However, the magnitude of these digestive effects is dependent on the amount of fermentable OM ingested.

Incidence ofPenicillium roqueforti and roquefortine C in silages

Wilted grass and whole-crop maize silages taken from farm silos in northern Germany were analysed for fermentation pattern, mould counts and composition of mycoflora as well as for roquefortine C. In general, increasing DM contents of visibly unmoulded silages resulted in decreasing amounts of volatile fatty acids and a greater portion of samples with a high number of mould propagules. The average mould count of these silages was found to be 1·4×104 cfu g−1, whereas visibly moulded samples contained about 1×108 cfu g−1. Penicillium roqueforti was the predominating fungal species in silages occasionally accompanied by species of the genera Aspergillus, Mucor, Monascus and/or Geotrichum. Penicillium roqueforti was detected in 89% of the visibly moulded and in 85% of the visibly unmoulded samples. Of 24 visibly moulded silages tested, 21 samples contained roquefortine C, a mycotoxin known to be produced by P roqueforti. The highest level of roquefortine C found was 36 mg kg−1 DM. Even 6 of 24 visibly unmoulded samples analysed for this mycotoxin were contaminated with roquefortine C but only in trace amounts. Roquefortine C is considered as a model compound for the biosynthesis of toxic fungal metabolites produced by P roqueforti in silages. The P roqueforti-count can be employed as a criterion to predict the contamination of silages with mycotoxins produced by this fungal species. © 1998 SCI.

Substitution of concentrates by ensiled high-moisture maize grain in dairy cattle diets

The effect of substitution of concentrates by ensiled ground high-moisture maize grain on voluntary feed intake and milk production by dairy cattle was investigated. In the first trial, 5.3 kg of concentrate (control ration) was substituted by 6 kg high-moisture maize grain (3.65 kg dry matter (DM)), 1 kg soybean meal and 400 g of a mineral-vitamin mixture (experimental ration). In the second trial, the concentrate supply was individually adapted to the requirements. This concentrate was partially or totally substituted by high-moisture maize grain, 1 kg soybean meal and 350 g of the mineral-vitamin mixture. The quantity of maize grain was restricted to 6 kg and averaged 5.25 kg (3.24 kg DM). The two trials were carried out according to a cross-over design with 10 and 12 lactating Holstein cows, respectively. The basal ration consisted of 60% (DM basis) whole-crop maize silage and 40% pre-wilted grass silage. The ensiled maize grain had a DM content of 614 g kg −1, an in vitro organic matter (OM) digestibility of 87.3% and an estimated net energy value of 8.61 MJ kg −1 DM. The maize grain was well preserved. In the two trials, roughage intake was 0.7 and 0.4 kg DM lower for the experimental rations, whereas total DM intake was 0.4 and 0.1 kg lower. For the control and experimental ration, the average milk yield was 26.1 kg and 25.9 kg in Trial 1, and 24.9 kg and 24.5 kg in Trial 2, respectively. Milk fat content was 0.09 and 0.07 percentage units lower for the experimental rations, whereas milk protein content hardly differed. In contrast to the somewhat lower milk fat and milk protein yield, the daily liveweight gain was 90 and 119 g higher for the rations containing maize grain.

Yeasts and fungi occurring in ensiled whole-crop maize and other ensiled vegetable crops

The yeast flora of whole-crop maize ensiled for two weeks was predominated by Candida holmii, C. lambica, C. milleri, Hansenula anomala and Saccharomyces dairensis. Inoculation with other yeast species reported in the literature to prevail in maize or wheat silages did not alter the yeast flora. At 25 or 30 degrees C the ascomycetous fermentative species found at 20 degrees C were accompanied with ascomycetous non-fermentative fungi, i.c. Exophiala jeanselmei and Verticillium psalliotae, by the non-fermentative imperfect basidiomycetous yeast Rhodotorula mucilaginosa and by the weakly fermentative imperfect ascomycetous yeast Trichosporon adeninovorans. The yeast flora of other vegetable crops, ensiled at 20 degrees C for two weeks, was predominated by the same species that prevailed in ensiled maize, provided the crop did not contain mustard oils or menthol. If these compounds occurred in the crops, the yeast flora was predominated by nonfermentative species like Candida famata, Stephanoascus ciferrii, Rhodotorula minuta, Rh. rubra and Trichosporon cutaneum.

Effect of sodium acrylate and calcium and sodium hydroxides on the fermentation, digestibility, chemical composition and aerobic deterioration of whole-crop maize silage

Whole-crop maize was harvested at a dry matter (DM) content of 33.2% and ensiled in polythene bag silos containing, on average, 2.75 kg DM, without additive (C) or with the addition of sodium acrylate (SA), calcium hydroxide (CH) or sodium hydroxide (SH), at intended application rates of 12.5, 50 and 50 g kg −1 of crop DM, respectively. After 60 days, all the silages were apparently well preserved and only the CH silage contained a trace of butyric acid; none of the silages contained more than 5% of the nitrogen in the form of ammonia. Bacterial fermentation was restricted by the addition of SA and enhanced by the use of CH and SH. Total fermentation acids formed 5.24, 3.25, 10.28 and 11.68% of the silage DM for C, SA, SH and CH silages, respectively. Ethanol production was relatively high when bacterial fermentation was restricted. The digestibility of organic matter was increased by SH from 72.5 for the C silage to 80.0%. All silages heated when exposed to air, an effect which was lowest for SA. The SH and CH silages heated extensively and after 14 days of exposure had lost over 30% of the original DM. It is concluded that SA may have a place in ensiling whole-crop maize, but that SH and CH do not.

Laboratory evaluation of ensiled mixtures of alkali-treated cattle excreta and whole-crop maize

Faeces or manure (faeces + urine + straw bedding) from beef cattle given maize silage diets were ensiled with whole-crop maize (27% dry matter), after treatment with NaOH at 0, 7.5 or 15 g per 100 g excreta DM, so that excreta DM comprised 25, 50 or 100% of the total DM, in a factorial design. A control treatment consisted of maize forage ensiled alone. The ensiled products were analysed for the content of fermentation acids, pH, nitrogenous compounds, structural carbohydrates, starch, water-soluble carbohydrates, ash, sodium and digestibility in vitro. Mixtures which contained 25% excreta DM were well preserved with relatively low values for pH, butyric acid and ammonia-N, and a high proportion of fermentation acids as lactic acid. Mixtures which contained 50% excreta DM were generally poorly preserved. Addition of NaOH to excreta prior to ensiling was reflected in a decrease in the content of neutral detergent fibre and increased digestibility of organic matter in vitro in the ensiled products. Mixtures of 25% excreta treated with 15 g NaOH/100 g excreta DM gave values for digestibility in vitro similar to that of the maize ensiled alone.

The utilization of dried forage crops by growing ruminants

SUMMARYMixtures (1: 1) of whole-crop dried wheat or barley, with peas or beans as a nitrogen supplement, were fed ad libitum to four groups of 16 6-mo-old male castrate sheep for a period of 42 days in 1971. The mean dry-matter consumptions (kg/day) and live-weight gains (g/day) were: wheat+peas 1·69, 264; wheat+beans 2·05, 288; barley+peas 1·80, 282; and barley+beans 1·81, 229. This experiment was repeated in 1972. The differences between treatments were non-significant.Dried pelleted whole-crop maize was fed ad libitum to British Friesian steers for 90 days, in conjunction with molasses and one of three protein sources, soya bean meal, urea or whole crop beans. The dry-matter intakes (kg/day) and live-weight gains (kg) were: maize+soya 9·68, 1·26; maize+urea 9·38, 10·4; and maize+beans 9·72, 1·15.Dried maize in conjunction with urea, whole crop beans and dried grass to supply crude protein levels between 9 and 11% was fed to 48 Hereford × British Friesian steers. The dry-matter intakes (kg/day) and live-weight gains (kg/day) were: whole crop maize, 8·35, 0·87; whole crop maize+urea, 9·55, 1·0; whole crop maize+whole crop beans, 7·44, 0·70; whole crop maize+dried grass, 8·94, 1·15; whole crop maize+rolled barley, 9·30, 1·23; and dried grass + rolled barley, 9·24, 1·21. Although there was no significant difference in live-weight gain between the treatments, two levels of performance were apparent.

Voluntary intake and efficiency of utilisation of whole-crop maize silage

The process of ensiling whole-crop maize is associated with major changes in composition which appear to be detrimental to nutritive value. Of particular significance is the production of organic acids and the degradation of plant protein to non-protein nitrogen (NPN). Intake may be increased by restricting fermentation, and since less fermentation occurs in drier crops than in wet, immature crops, the ensiling of crops at dry matter contents of 30–35% is recommended. There is also an improvement in net energy as the crop matures, which is related to an increase in starch content and a decrease in cell wall content. The extent to which supplementary NPN can be exploited in diets based on maize silage is limited by low levels of energy intake, and a relatively high content of NPN in the silage as a result of the fermentation process. In the presence of supplementary energy, differences in utilisation between sources of supplementary nitrogen are minimal. Many experiments have confounded energy intake with source of supplementary N, and more research is needed to understand fully the factors affecting rumen microbial protein synthesis in productive cattle.