The feeding value for ruminants of straw and wholecrop barley and oats treated with anhydrous or aqueous ammonia or urea

Ammonia-treated or untreated barley straw supplemented with urea was given as the only feed to two groups of Friesian heifers weighing approximately 550 kg. The digestibility of dry matter (DM) was 58.8 and 49.9%, daily feed intake was 5.88 and 3.87 kg and daily liveweight change was +324 and -447 g for the ammonia-treated and control barley straw diets, respectively.Anhydrous or aqueous ammonia (NH₃) was injected into large round straw bales covered with plastic. The rates of degradation of barley straw in nylon bags and digestibility in vivo were the same for both ammonia treatments. The distribution of N in the bales was also similar and uniform with both treatments. No differences were recorded in the rate of degradation in nylon bags if the plastic was removed 2 or 8 weeks after treatment.Anhydrous or aqueous ammonia or isonitrogenous amounts of urea were injected into large round bags containing whole-crop barley or oats collected with a forage harvester. The digestibility of starch by steers was about 92% for ammonia-treated samples and 78% for the urea-treated samples. Urea and ammonia efficiently preserved the whole-crop materials but untreated control samples and samples treated with NaOH deteriorated during storage.     

Ammonia-treated barley straw and rolled barley offered either together, in a mixed ration, or successively to beef steers

Barley straw treated with anhydrous ammonia at a rate of 40 g per kg of straw dry matter (DM) and rolled barley were offered to 20 steers weighing initially 350 kg. Each steer was offered in total approximately 600 kg of straw DM and approximately 525 kg of barley DM. Ten steers were offered the straw alone in the long form at the beginning of the trial followed by the rolled barley alone. The remaining 10 steers were offered straw which had been ground through a 40-mm screen and mixed with the rolled barley in a complete diet. Dry matter digestibility coefficients of the ammonia-treated straw and the mixed straw plus barley diet were 0.52 and 0.57 ± 0.026, respectively. The DM digestibility coefficient of rolled grain in the mixed diet was predicted from the digestibility of starch to be 0.78 and the DM digestibility of straw in the mixed diet, determined by difference, was 0.39. Although steers offered the straw followed by rolled barley took on average 39 days longer to consume their total food allowance, cold dressed carcass weights of the two groups were not significantly different nor was there any difference in the carcass composition of the two groups of steers as determined by specific gravity measurements. Maintenance energy requirements were calculated for the two groups of steers and although the same amount of food was consumed by both groups and the energy required for maintenance was higher in the group offered straw followed by barley, the depression in the energy available from straw offered in a mixed diet caused the same total amount of metabolizable energy to be available for carcass gain to both groups.     

Digestion of organic matter and nitrogen in ammoniated barley straw

Barley straw, either treated with anhydrous ammonia (40 g/kg for 28 days) or untreated, was chaffed and given to sheep in an intake and digestibility trial, or was ground and incubated in nylon bags in the rumen of sheep fed on lucerne or untreated or ammoniated straw.Ammoniation increased the N content from 2.45 to 10.63 g/kg dry matter (DM). Of the increment, 67% was retained in water-soluble form and 11.5% was in the cell wall organic matter (CWOM). The water-soluble N appeared to be retained by sheep as well as urea-N given with untreated straw; digestibility coefficients obtained in vivo, and by nylon bag incubation, suggested that N in CWOM was largely unavailable.Ammonia treatment increased the potential digestibility (measured by nylon bag incubation) of DM and CWOM by 23 and 29%, respectively. Digestibility in vivo of OM increased from 0.42 to 0.60 and of CWOM from 0.48 to 0.67. Intake of ammoniated straw increased over the 23-day feeding period, while that of untreated straw given with or without urea was constant or declined.     

Utilization of alkali-treated grain. 2. Utilization by steers of diets based on hay or straw and mixed with either NaOH-treated or rolled barley

In the first of three experiments, Hereford cross steers were fed ad libitum from 325 kg to slaughter at 425 kg on diets containing 50% hay and 50% rolled or NaOH-treated (30 g/kg) barley. Liveweight gain and food conversion ratios were similar for the two groups (1.24 vs. 1.42 kg/day; 7.0 vs. 7.0 kg dry matter intake/kg gain, respectively). Dry matter and organic matter digestibility was significantly higher (P < 0.01) when the diet contained rolled, rather than NaOH-treated, barley. There were no significant differences in fibre digestibility (51.2 vs. 59.1%, respectively).In the second experiment, the optimum level of NaOH was determined for the treatment of barley when given with hay. The level of NaOH required to achieve a digestibility in whole barley similar to rolled barley was 40 g NaOH/kg, i.e., approximately 10 g/kg more than when NaOH-treated barley formed the sole component of the diet. Dry matter and organic matter digestibility increased linearly as the level of NaOH applied increased (P < 0.05) and tended to peak at 40 g NaOH/kg barley. Starch digestibility also increased linearly (P < 0.001). Fibre digestibility did not vary significantly between treatments.In the third experiment, the voluntary intake of straw by steers given rolled or NaOH-treated barley at two levels of supplementation was determined. The intake of straw was slightly, but not significantly, greater when NaOH-treated rather than rolled barley was used. The digestibility of dry matter, organic matter, starch and fibre was not significantly affected by method of cereal treatment. No problems of animal health arose throughout the three experiments.     

Effects of treatment of barley straw with anhydrous ammonia and supplementation with heat-treated protein meals on feed intake and liveweight performance of growing lambs

Two feeding experiments were conducted in which lambs were given a basal diet of barley straw, supplemented with urea and minerals. The aim of the experiments was to increase lamb performance by (i) supplementation of the diet with protein meals that were largely undegraded in the rumen, (ii) treating the barley straw with anhydrous ammonia to increase its digestibility, or (iii) a combination of both.In Experiment 1, lambs were given the basal diet supplemented with 0, 60, 120, 180, 240, 300 or 360 g heat-treated protein-meal/kg straw. At the 300 g/kg level of supplementation, the protein pellet increased liveweight gain by 82 g/day, intake of barley straw by 110 g/day, and wool growth by 3.3 g/day, in comparison with unsupplemented lambs.In Experiment 2, untreated barley-straw or barley straw treated with anhydrous ammonia (4% w/w) was given to growing lambs. Each diet was supplemented (g/kg straw diet) with 100, 200 or 300 of two heat-treated protein-meals. Ammoniation of the barley straw increased dry matter (DM) digestibility in vitro from 49 to 57%, and hemicellulose content was reduced by 20%. Total N content of the straw was increased from 4.6 to 9.8 gN/kg DM by ammoniation, 65% of the increased N being potentially degradable in the rumen. As a result of ammoniation, digestible dry-matter intake of lambs was increased by 60 g DM/day and liveweight gain increased by 15 g/day.There was no significant difference between the two protein supplements with respect to either total feed intake or liveweight gain. Liveweight gain was significantly increased by both supplements (71, 106 and 125 g/day for each level of supplementation, respectively), but neither supplement had a significant effect on the intake of barley straw.Supplementation of a low-protein, low digestible diet of barley straw with a pelleted protein-meal considerably increased liveweight gain of growing lambs and maintained straw intake. By comparison, treatment of barley straw with anhydrous ammonia increased its digestibility, but had only a minor effect on lamb performance.     

Utilization of alkali-treated grain. 1. Alkali-treated grain in complete diets for steers and lambs

In one experiment, 32 lambs were offered (ad libitum) diets based on whole or NaOH-treated barley, or whole or NaOH-treated oats. The live-weight gains from 17 to 35 kg live weight were 371, 290, 258 and 229 g/day, respectively, while the calculated carcass weight gains were 190, 161, 86 and 118 g/day, respectively. There were large differences in the gut contents at slaughter which were 5.0, 3.3, 9.2 and 3.0 kg for the four diets, respectively.Forty-eight, Hereford-cross steers were allocated to six dietary treatments which consisted of unrestricted access to one of the following diets: NaOH-treated barley; rolled barley; NaOH-treated oats; rolled oats; NaOH-treated wheat; or NaOH-treated maize. The steers were fattened from 325 to 425 kg live weight. The average live weight gains were 1.56, 1.91, 1.37, 1.38, 1.49 and 1.42 kg/day, respectively. The steers receiving rolled barley achieved the greatest live weight gains (P < 0.05). The rumen contents at slaughter were 19.8, 32.2, 24.2, 46.0, 20.8 and 18.4 kg, respectively. Because of differences in gut contents, the only significant differences in carcass weight gain were found for the steers receiving rolled oats, for which carcass gain was lower than that for any other treatment (P < 0.001).Sixteen, Hereford-cross steers were allowed free access to diets containing either NaOH-treated barley alone, or NaOH-treated barley mixed with 10% of chopped straw. The live weight gains from 325 to 425 kg live weight were 1.55 and 1.07 kg/day, and food conversion was 5.7 and 8.4 kg feed/kg gain respectively.     

Influence of a Fusarium culmorum inoculation of wheat on the progression of mycotoxin accumulation, ingredient concentrations and ruminal in sacco dry matter degradation of wheat residues

The Fusarium head blight (FHB)-susceptible winter wheat cv. Ritmo was inoculated with spores of Fusarium culmorum at the beginning of full blossom. Samples of whole wheat plants were taken once weekly from anthesis until harvest and subsequently fractionated into straw, glumes and spindles, which were examined for deoxynivalenol (DON) and zearalenone (ZON). Additionally, the content of crude protein (CP) and non-starch polysaccharides (NSP) was scrutinized. Synthesis of the Fusarium toxins DON and ZON generally differed in terms of date of formation and concentration. Final mean DON concentrations of 37.5, 28.1 and 5.0 mg/kg DM were measured in glumes, spindles and straw, respectively, at the time of harvest. At this time, maximal mean ZON concentrations of 587, 396 and 275 microg/kg DM in spindles, glumes and straw, respectively, were determined. Moreover, Fusarium infected wheat residues contained higher CP but lower NSP contents at the last three sampling dates. In addition, collective samples of wheat straw and chaff were taken to investigate the effect of the Fusarium contamination on their in sacco DM degradation in dairy cows. Samples were analysed for mycotoxins and selected quality parameters. The dried and milled collective samples of straw and chaff were weighed into nylon bags and subjected to ruminal incubation for 4, 8, 16, 24, 48, 72, 96 and 120 h in two dairy cows equipped with a permanent rumen cannula. Marked differences in level of mycotoxin contamination as well as in ingredient composition between the variants of straw and chaff were detected. Moreover, after 120 h rumen incubation the in sacco DM degradation of inoculated straw and chaff were lower compared to the accordant controls. The soluble fraction was increased in inoculated samples, whereas a diminishment in the potentially degradable but insoluble fraction was more pronounced. Thereby, a decrease in the potential degradability was obtained for inoculated straw and even if less pronounced for chaff compared to the non inoculated corresponding controls. In conclusion, infection with F. culmorum of wheat involves an increased risk of mycotoxin contamination in straw. Also, a Fusarium infection may have an impact on chemical composition and may result in Fusarium growth-related modifications of host cell wall components.     

Plasmalogens of microbial communities associated with barley straw and clover in the rumen

Abstract: Microbial plasmalogen aldehydes (detected as dimethyl acetals, DMA) have been used to compare microbial populations associated with clover and barley straw incubated in nylon mesh bags in the rumen of a cow. The results suggest that the populations involved in the digestion of these substrates differ substantially and that population changes occur as digestion proceeds: these conclusions were supported by electron-microscopic observations. Analysis of DMA suggested that populations associated with the particles of straw and clover differed more markedly than the corresponding populations in the liquid phase. When straw was pre-incubated with the rumen cellulolytic bacterium Ruminococcus flavefaciens strain 17, the DMA characteristic of this bacterium were present at increased levels during subsequent incubation of the straw in the rumen, though the R. flavefaciens DMA tended to contribute a smaller proportion of the total DMA as the incubation time in the rumen was increased from 24 to 72h.     

Utilization of alkali-treated grain. 3. Utilization by steers of NaOH-treated and rolled barley in silage-based diets

In the first of three experiments, silage constituted 33 or 66% of the dry matter of complete diets, barley being the other component. The barley was either rolled, or treated with 30 g NaOH/kg dry matter. In two further treatments, the NaOH-treated barley was given in separate feeds, while silage was offered ad libitum. The diets were offered ad libitum to 32 Hereford cross steers from 325 kg live weight to slaughter at 450 kg live weight. Growth rate increased and feed conversion ratio decreased as the precentage of barley in the diet increased, but were significantly poorer with NaOH-treated than with rolled barley owing to the significantly lower digestibility of dry matter, organic matter and starch in diets containing NaOH-treated grain.In the second experiment, the effect on digestibility of increasing the NaOH added to the barley used in the mixed diets was investigated with steers. The results showed that the level of NaOH application had to be greater when NaOH-treated barley was used in mixed feeds than when it was used as the sole feed. The optimum rate of application in silage based diets was in the region of 45 g NaOH/kg dry matter.In the third experiment, forty Hereford cross steers were allocated to one of four treatments and were fattened from 325 to about 450 kg live weight. They were given (dry matter basis) 50% silage and 50% of barley, either rolled (RM) or treated with 45 g/kg NaOH (CM), mixed together, or they were given the silage alone until they had eaten the allocated quantity and then the allocated barley; the barley was either rolled (RS) or treated with 30 g/kg of NaOH (CS). The same quantities of silage and grain were given to all steers. The steers fed on silage and grain separately took, on average, 125 days to consume the feed (70 days for consumption of silage), but had similar carcass weights to the steers given mixed diets, which consumed their feed in 91 days. The growth rates for treatments RM, CM, RS and CS, respectively, were 1.15, 1.20, 0.89 and 0.78 kg/day, the food consumption was 737, 741, 728 and 741 kg dry matter and the final carcass weights were 256, 253, 247 and 252 kg. There were no significant differences between steers receiving the diets containing rolled or NaOH-treated barley.     

Effects of oilseed meals and grain–urea supplements fed infrequently on digestion in sheep: 2. Cereal straw diets

An experiment examined the intake, growth responses and rumen digestion of young sheep fed ad libitum oat or barley straws alone or supplemented with approximately isonitrogenous amounts of barley grain and urea (Bar/N), safflower seed meal (SAF) or linseed meal (LIN) supplements provided at 3 day intervals. The supplements comprised 15–22% of total dry matter (DM) intake. Sheep offered either of the straws alone consumed 35.0–37.2 g DM/kg liveweight (LW^0.75) per day of straw and an estimated 2.03–2.07 MJ metabolizable energy (ME) per day, and lost 85–97 g LW per day. Supplements increased (P<0.05 or <0.001) voluntary intake of straw and of total DM, and the organic matter (OM) digestibility of the entire diet. Each of the supplements increased (P<0.001) the estimated ME intake to a similar extent and changed the rapid LW loss of sheep fed straw alone to approximate LW maintenance. Rumen ammonia concentrations in sheep fed barley and oat straws alone (12 and 24 mg NH₃/l, respectively) were expected to be deficient for microbial activity, but were increased (P<0.001) by provision of the supplements. Digestion of straw in synthetic fibre bags incubated in the rumen was markedly increased (P<0.01 or <0.001) when supplements were provided. Rumen pH was depressed briefly to pH <6.0 by the Bar/N, but not by the LIN or SAF, supplements. In young sheep fed cereal straws and losing LW rapidly the oilseed meal supplements increased wool growth more than the barley grain–urea supplements, but both types of supplement increased ME intake similarly and were equally effective to reduce the extent of LW loss.     

黑龙江不同玉米秸秆还田方式下土壤动物群落结构及其对秸秆降解的影响

以黑龙江省海伦市典型黑土耕地为试验样区,研究黑土区不同秸秆还田方式下土壤动物群落结构特征及其在秸秆降解中的作用。实验选取6目、30目、260目降解袋,设置5个处理:17kg玉米秸秆+2kg水还田+含微生物100%浓度催腐剂(样方A)、8.5kg玉米秸秆+1kg水还田+含微生物50%浓度催腐剂(样方B)、原始样方(样方C)、8.5kg玉米秸秆+1kg水还田(样方D)、17kg玉米秸秆+2kg水还田(样方E),并于2009—2011每年9月份测定不同样方的玉米秸秆降解率和微生物数量。结果表明:所有样方累积秸秆降解率都达55%以上,秸秆降解率从高到低排序依次为:样方A>样方B>样方C>样方D>样方E;对秸秆降解起主要作用的动物类群为中小型土壤动物中的甲螨亚目、中气门亚目和节跳虫科,约占土壤动物个体数的86.70%;不同处理样方中,土壤动物群落结构相似;相同处理样方中,不同规格的降解袋中土壤动物个数与类群差异显著(P<0.001);不同孔径降解袋中土壤动物的个数、类群数、多样性基本都与秸秆降解率呈正相关,进一步表明土壤动物对秸秆降解具有促进作用。     

Alkali treatment of straw for ruminants. II. Nutritive value of straw ensiled after alkali treatment

In the first of two experiments barley straw was treated with a 16% solution of $\text{NaOH}\text{t}$ dry matter (DM) and ensiled for one year. It was satisfactorily preserved, having a pH of 10 and counts of 10⁴ mesophilic bacteria and 10³ fungal propagules per g. When this straw was mixed with concentrates (50:50, DM basis) and given to sheep, DM intake and digestibility were 102 g/kg W^0.75 per day and 67.3%. Comparable values for a diet based on freshly-treated straw were 88 g and 66.5%.In the second experiment, a 6-tonne batch of alkali-treated barley straw was ensiled for 2–4 months, then mixed with 40% concentrates and given to 370-kg steers for 66 days. Intake and growth rate were 10.23 and 1.08 kg/d, compared with 9.06 and 1.00 kg/d for steers given a diet based on freshly-treated straw. The latter diet was less digestible (for sheep) than the former.It is concluded that the feeding value of stored straw is as high as that of freshly-treated material.     

Wachstumsuntersuchungen an Bullen des Schwarzbunten Milchrindes (SMR) bei niedrigem Fütterungsniveau

Artificially dried ryegrass, untreated and ammonia‐treated wheat straw were ground and incubated in nylon bags in the rumen of three sheep each fed with diets based on roughage or concentrate. Dry matter degradability, the concentration and the release of the trace elements Cu, Fe, Mn and Zn from the incubated feeds were measured after 0 (washing loss), 6, 12, 24, 48 and 72 h rumen incubation time.

Dry matter degradability, trace element concentration and their release were significantly influenced by the kind of incubated feeds, incubation time and feeding of sheep.

Cu‐ (1.8–6.9 mg kg^?1 DM) and Zn concentrations (36–103 mg kg^?1 DM) of straw residues in the bags were much higher than those of original straw (1.2–1.6 and 8.1–9.9 mg kg^?1 DM resp.).

The inflow of Cu and Zn in the bags containing straw residues was higher than their release. The Cu‐, Fe‐ and Mn‐release from ryegrass was similar to the dry matter degradability, but the Zn‐release was much lower.     

Untersuchungen über die Druckammonisierung von kohlenhydrathaltigen Futterstoffen

Chopped wheat straw was homogeneously mixed with urine of horses (5.75 gN per 1, 16.88 atom‐% ¹⁵N‐excess) and airtightly stored in plastic containers for 6 months. Three rumen fistulated sheep and goats each were fed with untreated or urine treated straw. Concentrate was added to straw. Untreated and urine treated straw were given in nylon bags and incubated in the rumen of sheep and goats for 1, 3, 6, 12, 24, 48 and 72 hours. A three compartment exponential function was used to fit the measurements of ¹⁵N‐ex‐cess and ¹⁵N‐amount of bag content. The curves and the calculated partial Y‐values of the three compartments show the inflow and outflow of ¹⁵N into or from the bags and allow conclusions about the binding of urine N. Most N of urine was not compactly bound by straw during storage. Primarily micro‐bial N was attached to the straw in the rumen. About 6% of urine N were bound more compact to the straw. Similar curves were calculated for ¹⁵N‐excess and ¹⁵N‐amount of nylon bags. The curves allow conclusions about tracer flows without quantitative knowledge. There were no significant differences between animal species.     

Validation of in sacco method: influence of sampling site,nylon bag or rumen contents,on fibrolytic activity of solid-associated microorganisms

Three ruminally cannulated cows, fed twice daily with a 70:30 forage:concentrate diet, were used to investigate the differences in fibrolytic activity of solid-associated microorganisms between nylon bags and rumen contents. Two different grass hays (regrowth and late harvested) were incubated in ruminal nylon bags. After 2 h or 23 h incubation time, pH was measured in bags and rumen contents, and enzymes of solid-associated microorganisms were extracted from bag residues and surrounding digesta by grinding, freezing, defrosting and sonication. Xylanase, avicelase, β-D-xylosidase and β-D-glucosidase activities were measured. Activities were lower in bag residues than in rumen digesta, and differences were greater after 2 h than after 23 h incubation time. Causes of these differences are discussed. For each incubation time and each enzyme, the differences in solid-associated microorganisms activities between rumen and bags contents were independent of the quality of hay in the bag. Thus the lower fibrolytic activity inside the bags may account for an underestimation of in vivo ruminal fiber degradation by the in sacco method, but this underestimation may be similar whatever the nature and content of forage cell walls.     

The development of an intraruminal nylon bag technique using non-fistulated animals to assess the rumen degradability of dietary plant materials

Although the conventional in situ ruminal degradability method is a relevant tool to describe the nutritional value of ruminant feeds, its need for rumen-fistulated animals may impose a restriction on its use when considering animal welfare issues and cost. The aim of the present work was to develop a ruminal degradability technique which avoids using surgically prepared animals. The concept was to orally dose a series of porous bags containing the test feeds at different times before slaughter, when the bags would be removed from the rumen for degradation measurement. Bags, smaller than those used in the conventional nylon bag technique, were made from woven nylon fabric, following two shape designs (rectangular flat shape, tetrahedral shape) and were fitted with one of three types of device for preventing their regurgitation. These bags were used in two experiments with individually housed non-pregnant, non-lactating sheep, as host animals for the in situ ruminal incubation of forage substrates. The bags were closed at the top edge by machine stitching and wrapped in tissue paper before oral dosing. Standard times for ruminal incubation of substrates in all of the tests were 4, 8, 16, 24, 48, 72 and 96 h before slaughter. The purpose of the first experiment was to compare the effectiveness of the three anti-regurgitation device designs, constructed from nylon cable ties (‘Z-shaped’, ARD1; ‘double Z-shaped’, ARD2; ‘umbrella-shaped’, ARD3), and to observe whether viable degradation curves could be generated using grass hay as the substrate. In the second experiment, three other substrates (perennial ryegrass, red clover and barley straw) were compared using flat and tetrahedral bags fitted with type ARD1 anti-regurgitation devices. Non-linear mixed-effect regression models were used to fit asymptotic exponential curves of the percentage dry matter loss of the four substrates against time of incubation in the reticulorumen, and the effect of type of anti-regurgitation device and the shape of nylon bag. All three devices were highly successful at preventing regurgitation with 93% to 100% of dosed bags being recovered in the reticulorumen at slaughter. Ruminal degradation data obtained for tested forages were in accordance with those expected from the conventional degradability technique using fistulated animals, with no significant differences in the asymptotic values of degradation curves between bag shape or anti-regurgitation device. The results of this research demonstrate the potential for using a small bag technique with intact sheep to characterise the in situ ruminal degradability of roughages.     

Electron Microscopy of the Microbial Populations Present and Their Modes of Attack on Various Cellulosic Substrates Undergoing Digestion in the Sheep Rumen

Cotton fibers and various cell wall preparations from grass leaves and from the feces of sheep fed on dried grass were placed in the sheep rumen in bags made from 5-μm-mesh nylon cloth. After periods of from 3 to 48 h, bags were removed, and the contents were fixed, embedded, sectioned, and stained for electron microscopy. Some of the bacteria present were seen to be closely associated with the cell walls, either tunneling within them or making very close contact. Evidence was obtained for differential digestion of cell walls and of the layers within them. Distinct differences were noticed between bacterial populations attacking the more susceptible wall types and those attacking feces cell walls and cotton fibers. Among the latter, the dominant form was a long, thin rod with a typical gramnegative cell wall structure, different from that described for Bacteroides succinogenes S85 or for Butyrivibrio fibrisolvens.     

Effect of starch level and straw intake on animal performance, rumen wall characteristics and liver abscesses in intensively fed Friesian bulls

The objective was to reduce the incidence of liver abscesses (LAs) in young bulls by reducing the starch content of the concentrate and increasing the straw intake by adding molasses without reducing performance. Eighty-five Danish Friesian bulls (146 ± 2.6 kg live weight (LW)) were allocated to four treatment groups in a 2 × 2 factorial design and were ad libitum fed either a high (H) (43%) or a low (L) (25%) starch concentrate, and either chopped barley straw (S) or a mixture (Sm) of chopped barley straw and sugar-beet molasses (75:25). The bulls were slaughtered at 440 (±4.2) kg LW (11.3 months of age) on average. The concentrate dry-matter intake (DMI) was 7.5% higher (P < 0.001), the roughage DMI was 12% higher (P < 0.01), whereas the total net energy intake was 7% lower (P < 0.001) for the L compared with the H concentrate. By adding molasses to the straw, roughage DMI increased from 0.50 to 0.96 kg/day (P < 0.001). Average daily gain (ADG) was not affected by treatment. Feed conversion efficiency (FCE) for dry matter (FCEDM) was decreased (P < 0.001), whereas FCE for net energy (FCENE) was increased with the L concentrate (P < 0.01), suggesting a lower utilisation of the cell wall fraction with the H starch concentrate. There were no major effects of treatment on carcass characteristics. The higher roughage intake with Sm prevented rumen wall damage, but did not reduce the number of animals with LAs. The L concentrate did not affect the rumen wall but reduced the level of LA (2 v. 9 animals, P < 0.02). There was a higher level of respiratory diseases in animals fed the H concentrate (P < 0.05). The experiment showed that it was possible to maintain performance and reduce LA by using a lower starch content of the concentrate.     

Chemical defense in birch: Inhibition of digestibility in ruminants by phenolic extracts

Summary The biological activity of phenolic extracts originating from winter twigs of birch (Betula pendula Roth.) was measured using the ruminant in vitro method and the nylon bag technique. Different extracts were prepared by extraction with organic solvents, removing phenols of corresponding solubility. The extract of birch twigs (diameter <1.5 mm) contained about 19% phenol equivalents, corresponding to 6% of twig dry matter (DM). Coarse birch twigs (diameter 1.5–5 mm) contained about 3% in the DM Phenolic extracts from the fine birch twigs were added to coarse birch twigs and common timothy (Phleum pratense L.) to mimic natural concentrations of fine birch twigs. Controls and the plant material with phenolic extract added were incubated for different times with rumen inocula taken from a sheep fed browse and a goat fed hay. Nylon bags containing phenolic treated hay were incubated in the rumen of the goat for 6 and 48 h. Phenolic extracts had a considerable negative effect on the organic matter (OM), protein and cell wall (neutral detergent fiber, NDF) digestibility in vitro. The nylon bag OM disappearance was also depressed by the extract. The effects were measurable after 6 h of digestion both in vitro and in sacco.The high inhibitory effect by the extracts on digestibility persisted even after removal of lipophilic fractions. This suggests that some or several water-soluble phenolic substances are responsible for the depression of digestibility. The depression of OM digestibility is linearly related to the concentration of phenols added. However, the inhibition of nylon bag digestibility plateaus at high phenol concentrations, suggesting that some fraction of the substances undergo complex formation with macromolecules of the plant.The results strongly indicate that water-soluble phenols of birch make up an important part of its chemical defense in winter by possessing antinutritional properties. Thus their potential importance in the nutrition of wild herbivores must not be ignored.     

Studies on ammonia-treated straw. II. Fixation of ammonia in treated straw by spraying with acids

Ammonia-treated barley straw (NH₃ straw) was sprayed with either formic, acetic or phosphoric acid immediately after opening the stack in order to capture the excess ammonia. The amount of acid applied was estimated to neutralize 100% of the ammonia added to the straw (30 kg NH₃/t straw). After spraying with acid the straw was stored in plastic bags for about 8 weeks at room temperature (15–20° C). When bags of NH₃ straw treated with acids were opened, there was very little smell of ammonia whereas there was a very strong smell from the bag of NH₃ straw without acid added.The nitrogen content of the straw (g/100 g DM) was for untreated straw, 0.88, NH₃ straw without acid, 2.50, and NH₃ straw with added formic acid, 3.49, acetic acid, 3.81, and phosphoric acid, 2.27. The digestibility of organic matter determined in sheep was 47.3, 60.5, 59.0, 60.4 and 51.3 following the same order as above.It is concluded that spraying NH₃ straw with organic acids effectively reduces the loss of ammonia and increases the nitrogen content of the straw. Another advantage of this is that the air pollution with ammonia which may occur in the barn when the straw is not well aired is effectively prevented.Spraying with organic acids had no negative effect on the digestibility of the straw. The nitrogen supply and the digestibility of nitrogen in the animal seemed to be markedly improved.