Modified Acid Detergent Fibre Research Articles

Trace element composition of tree fodder and potential nutritional use for livestock

Silvopastoral agroforestry, the integration of trees into livestock production systems, is an ancient practice with benefits to animal welfare and nutrition. Intensification of farming practices have reduced the presence of trees and hedgerows in the agricultural landscape. Environmental benefits coupled with improvements to ecological resilience and the long-term sustainability of farm productivity have led to a resurgence in interest in silvopastoral farming systems. The objective of this study was to investigate the nutritional composition and potential use of tree leaves as a supplementary fodder for ruminant livestock, with particular reference to sheep.Leaves (including petioles) were collected during spring (June) and autumn (September) from goat willow (Salix caprea), oak (Quercus spp) and alder (Alnus spp) from three sites in the UK. On the third site samples of ash (Fraxinus excelsior), beech (Fagus sylvatica), sweet chestnut (Castenea sativa) and sycamore (Acer pseudoplatanus) were also collected. Tree leaves were analysed to determine mineral content, dry matter (DM), crude protein (CP), modified acid detergent fibre (MADF) and metabolisable energy (ME) which were then compared to the nutritional requirements of grazing sheep (Ovis aries).Leaves from all tree species used in this study were able to exceed the dietary ME and CP concentration requirements (NRC) for growing lambs (40 kg lamb @ 150 g/d). Alder contained the most ME and CP of the studied species. There was no significant effect of season although CP was higher in spring than autumn for all tree species.Zinc and cobalt concentrations were found to be dependent on tree species with negligible site and season effects. All (NRC) sheep requirements of both elements were exceeded by willow, met by alder and not met by oak, willow exceeded these requirements for zinc and cobalt by approximately 3-6 and 10-15 fold respectively. Leaf selenium concentrations were site specific with site 1 almost able to meet maximal requirement, whilst all other sites (all tree species) were around the minimal requirement.To conclude, ME and CP concentrations of the tree leaves were generally within a requirement range to support adequate growth of lambs if leaves fed alone (not likely in practice). Selenium concentrations were site dependant, iodine was mainly season dependent with tree species effects for zinc and cobalt. The zinc and especially cobalt concentrations of willow leaves were sufficient to suggest that willow could be used as a bio-supplement when fed within a conventional grazing system, especially useful for growing lambs.

Stocking Rate Has No Confounding Effect on the Use of Internal and Inert Markers to Predict Botanical Composition, Diet Quality, Degradability and Passage Rate Kinetics in Sheep

Simple SummaryInternal markers are components of diets recovered to different degrees in faeces of animals. These feed components maybe helpful in predicting diet selection, nutrient intake and digestibility in animals. The development of sustainable grazing management and practices to prevent the depletion of natural grasslands as a result of overgrazing depends on the knowledge of feed intake, chemical and botanical composition of diets selected and consumed by ruminants. Determination of the botanical composition of diets selected by free ranging ruminants by visual observation is time consuming and tedious, while the use of oesophageal cannulated animals is invasive and impairs animal welfare. Therefore, it is imperative to use non-invasive methods, such as internal markers to predict feed preferences and composition of diets that ruminants consume. However, it is unclear if the accuracy of results obtained using internal markers is confounded by other factors, such as stocking rate, which is expected to determine the availability and botanical composition of pasture, which, in turn, may exert its influence on the diet selected and consumed by grazing animals. The findings of this study, however, showed that stocking rates did not affect diet selection and nutrient intake in sheep, while a combination of internal markers can be used to estimate the quality of diet selected by animals under cafeteria feeding conditions, regardless of the stocking rate used. Thus, the use of modified acid detergent fibre, acid insoluble ash and acid detergent lignin contents in feeds achieved high accuracy and precision in estimating diets selected by sheep. This approach serves as a proof of concept that these markers can be also used in free ranging animals.This study investigated if there is any confounding effect of stocking rate on the use of internal markers to determine and predict the dietary ingredient composition, dry matter intake (DMI) and digestibility of diets consumed by sheep. Fifteen sheep were randomly allocated to stocking rate treatments of one (SR1), two (SR2), four (SR4) and eight (SR8) sheep per pen (space allowance: 31.04 m2, 15.52 m2, 7.76 m2 and 3.88 m2 per sheep, respectively) and fed ad libitum maize stover, sorghum stover and veld hay by supplying 110% of previous day’s intake. Sheep were rotated across the treatments in four periods of 10 days. The proportion of feeds selected and total DMI were similar across all stocking rate treatments. However, diets selected by sheep in SR2 had the highest digestibility compared to other treatments. The prediction of the effective degradability of dry matter using acid detergent fibre content achieved an accuracy of 84.6%. A combination of crude protein and neutral detergent fibre contents achieved 63% accuracy in the prediction of the rate of degradation of feeds. The use of acid insoluble ash (AIA) as an internal marker to predict nutrient intake, digestibility, DMI and dietary ingredient intake accounted for 84.3%, 81.2%, 53.0% and 64.1% of the variation, respectively. The predictions of dietary feed proportions and nutrient quality selected obtained with least squares procedure using a combination of modified acid detergent fibre (MADF), acid detergent lignin (ADL) and AIA accounted for 81.0% and 72.4% of the variation, respectively. In conclusion, regardless of the different stocking rate tested in this study, a combination of MADF, ADL and AIA as internal markers can be used to estimate diet and nutrient selection by sheep using the least squares procedure. Hence, these markers can be used to predict ingredient composition of diet, diet and nutrient selection, nutrient intake and digestibility in free ranging animals.

The Effects of Timing of an Interim Harvest on the Yield and Composition of Lablab purpureus

Lablab purpureus was grown in two field experiments in consecutive years to evaluate the effects of the timing of an interim harvest on the yield and nutritive value of the harvested material and the subsequent regrowth, which was determined from the second and final harvest. Delaying the first harvest to 50–70 days post‐sowing increased the total (first plus second harvests) dry matter (DM) yield, with a greater first harvest and reduced second harvest DM yield. The delay also reduced the crude protein concentration of the first harvest and tended to increase its modified acid‐detergent (MAD) fibre concentrations. The delay increased the crude protein concentration and decreased the MAD fibre concentration of the second harvest. The total crude protein yield of both harvests increased with late interim harvesting. The first harvest plant calcium concentration increased and phosphorus concentration decreased with a delay in the interim harvest. It is concluded that, in the difficult growing conditions of the Sahelian zone of sub‐Saharan Africa, delaying the interim harvest of Lablab purpureus until 50–70 days post‐sowing will have beneficial effects on total dry matter and crude protein yields.

Sheep grazing and defoliation of contrasting varieties of organically grown winter wheat with and without undersowing

Field experiments in Gloucestershire, UK, in the 1990–91, 1991–92, 1993–94 and 1994–95 growing seasons explored the merits of grazing in spring a traditional tall wheat (Triticum aestivum) variety, Maris Widgeon, with more modern shorter varieties. In the first 2 years, defoliation was achieved by mowing at 7 cm in March and/or April. In the second 2 years, varieties sown at two sowing dates were grazed by sheep at a stocking rate of 42 × 50 kg sheep ha−1 for 3 or 4 days in March. Defoliation reduced crop height and interception of photosynthetically active radiation (PAR). In 1991–92, mowing significantly reduced grain yield of some of the shorter varieties but not of Maris Widgeon. This interaction was related to the amount of PAR intercepted. In this year, mowing improved the establishment of undersown white clover (Trifolium repens) and perennial ryegrass (Lolium perenne), but in subsequent years the conditions were much drier and undersowing failed. In the last two experiments, grazing in March did not significantly reduce grain yield of any variety. The quality of the forage eaten by the sheep had a modified acid‐detergent fibre (MADF) content of less than 300 g kg−1 dry matter (DM) and a crude protein (CP) content of more than 200 g kg−1 DM in both seasons. Yield of DM and calculated metabolizable energy (ME) of different varieties removed by the sheep interacted strongly with sowing date. September‐sown Maris Widgeon provided ≈ 0·7 and 0·3 t DM ha−1 (or 7·8 and 3·4 GJ ME ha−1) in March 1994 and March 1995 respectively. However, the shorter wheat varieties, Hereward and Genesis, only provided 0·3 and 0·1 t DM ha−1 when sown at the same time in the 2 years. At later sowing dates all of the varieties only provided about 0·1 t DM ha−1 when sown in October 1993, or 0·01 t DM ha−1 when sown in November 1994. Sheep grazing reduced total weed biomass in June, and reduced the emergence of weed seedlings from soil samples collected after the wheat harvest. Effects of defoliation on foliar infection by Septoria tritici were inconsistent.

The effect of silage fermentation characteristics on dry-matter intake of steers

AbstractJuke was expressed from two silages of contrasting fermentation type with either high (H) or low (L) levels of lactic acid and reconstituted either with the silage from which it had been expressed or the other silage. This procedure produced four dietary treatments (HH, HL, LL, LH) each differing in fermentation characteristics. The dietary treatments HH, HL, LL, and LH contained 81, 71, 59, and 49 g lactic acid per kg dry matter (DM) and 101, 133, 193 and 159 g ammonia-N per kg total nitrogen (TN) respectively. The four diets were offered to four steers (mean live weight 679 (s.e. 49) kg) in a four-period change-over design experiment. Each period was of 17 days duration. DM intakes were recorded daily, with intakes on days 8 to 17 used in the statistical analysis of data. On day 12 of each experimental period, rumen fluid samples were taken throughout a 24-h period. The rates of disappearance of DM, nitrogen (N), modified acid-detergent fibre (MADF) and neutral-detergent fibre (NDF) in the rumen were determined on days 14 to 17 using the polyester bag technique. DM intakes were 7·2, 6·9, 6·0 and 6·0 (s.e. 0·50) kg/day (P = 0·08) for HH, HL, LL and LH dietary treatments respectively. Diet had no significant effect on eating behaviour, rumen fermentation parameters or degradability of DM, N, MADF and NDF fractions (P > 0·05). Silage L increased rumen fluid pH (P < 0·05), reduced buffering capacity (P < 0·05) and increased the molar proportion of propionic acid and n-butyric acid (P < 0·05 and P < 0·01) compared with silage H. Silage L also had a lower DM apparent digestibility, D-value and DM, (P < 0·001), N and MADF (P < 0·05) degradabilities than silage H. The higher DM intake of dietary treatment HH compared with dietary treatments LL and LH could not be explained by any single constituent of the silages although it was apparent that physical characteristics of the silage were more important in determining intake than the chemical characteristics.

The effect of infusion of putrescine and gamma amino butyric acid on the intake of steers offered grass silage containing three levels of lactic acid

An experiment was carried out to assess the role of putrescine (P) and gamma amino butyric acid (GABA) on the intake of grass silage containing three levels of lactic acid. The experimental design involved a nine period, 3 × 3 factorial changeover design experiment, with each period of 14 days duration. Putrescine and GABA were applied at a rate of 6 g kg −1 dry matter (DM), dissolved in 4 I water and intraruminally infused using a peristaltic pump with the amount infused varied throughout the day by means of an electronic time-switch attached to the infusion pump. (This was an attempt to match the amount infused with the amount the animal would have consumed if the treatment had been added to the diet.) The basal diet consisted of a well fermented grass silage with 116 g lactic acid kg −1 DM. Lactic acid was added to the basal diet at levels of 0, 50 and 100 g kg −1 DM to give final lactic acid concentrations of 116 (L1), 160 (L2) and 188 (L3) g kg −1 DM, respectively. No significant interactions between infusion treatment and level of lactic acid were observed on intake, eating behaviour, rumen fermentation parameters or dry matter, nitrogen, modified acid detergent fibre (MADF) or acid detergent fibre (ADF) degradability characteristics of silage. Main treatment effects only are presented. Putrescine and GABA did not significantly ( P > 0.05) affect dry matter intake or feeding behaviour. L2 significantly increased total time spent eating per day ( P < 0.05), reduced daily eating rate ( P < 0.001) and reduced mean eating rate during the secondary meals ( P < 0.001). Infusion of P increased rumen fluid pH ( P < 0.05). GABA infusion reduced the molar proportion of propionic acid ( P < 0.05) and increased total i-butyric acid concentration ( P < 0.05). L3 increased total concentration of n-butyric acid ( P < 0.05); L2 and L3 increased the molar proportion of n-butyric acid ( P < 0.05). Lactic acid treatment had no significant effect ( P > 0.05) on DM, N or MADF degradability characteristics. However, L3 reduced NDF degradability ( P < 0.05). Infusion treatment had no significant effect ( P > 0.05) on DM, MADF or NDF degradability characteristics. However, P reduced nitrogen degradability ( P < 0.01).

The Effect of Inclusion of Naked Oats in the Concentrate Offered to Dairy Cows on Milk Production, Milk Fat Composition and Properties

Dairy cows in early or mid-lactation were offered naked oats- or barley-based concentrates in addition to ad libitumaccess to grass silage in a continuous design experiment of 10 weeks duration. Concentrates were formulated on an isonitrogenous basis and contained either 500 g barley or 565 g naked oats kg−1 concentrates as the principal energy source in the concentrate. Concentrate type had no effect on silage intake, milk yield or milk protein concentration. However, nitrogen and modified acid detergent fibre digestibility were significantly reduced by inclusion of naked oats and this was reflected in a significant reduction in milk fat concentration. Milk fat from early lactation cows on the naked oats diet contained the highest proportion of unsaturated and the lowest proportion of saturated fatty acids. Sensory and instrumental analyses determined that this milk fat produced the softest, most spreadable butter. This was supported by solid fat content results. The degree of change in milk fat composition due to diet was similar irrespective of stage of lactation but milk fat compositions with the control treatment differed with stage of lactation. Dietary effects were established by the end of the first week of the trial and persisted for the 10-week trial period.

Effects of applying a bacterial inoculant to silage immediately before feeding on silage intake, digestibility, degradability and rumen volatile fatty acid concentrations in growing beef cattle

AbstractIn an experiment, involving twelve male cattle (initially 235 kg live weight), the effects of applying lactic acid bacteria [Lactobacillus plantarum; 109 colony‐forming units (g fresh silage)−1] to grass silage, immediately prior to that silage being fed, on dry‐matter (DM) intake of the silage, degradability of nitrogen (N) and fibre in the rumen, total tract digestibility and composition of rumen fluid in the animals were examined. A grass silage, which had been made from the primary growth of a predominantly perennial ryegrass sward, was offered as the sole diet. The inoculant was applied to the silage at the rate of 2 g of freeze‐dried powder reconstituted in 12 ml of water (kg fresh silage)−1 immediately prior to that silage being fed and an equivalent amount of water was applied to the silage in the control treatment. The two diets were compared in a change‐over design. The silage was well preserved, having a pH and concentrations of ammonia N and butyrate of 3.72, 74 g (kg total N)−1 and 0.11 g (kg DM)−1 respectively. Application of the inoculant significantly increased true protein, acid‐insoluble N and water‐soluble carbohydrate concentrations (P &lt; 0.001) in the diet. Silage DM intake was not significantly increased (P= 0.072) by this of inoculant treatment, which had no significant effect (P &gt; 0.05) on rumen degradability or total tract digestibility of DM, N, neutral detergent fibre or modified acid detergent fibre. Rumen pH, ammonia concentration or the molar proportions of volatile fatty acids were not altered (P&gt;0.05) by inoculant treatment. It is concluded that application of the inoculant to the silage prior to silage being fed did not significantly affect silage DM intake, total tract digestibility, or degradability or fermentation in the rumen of cattle offered grass silage as the sole diet. It is also concluded that the results of this experiment provide no evidence that the mode of action of L plantarum, applied as an additive to grass at ensiling in previous studies, is through ‘direct’ effects in the rumen.

The effects of treating low dry-matter, low digestibility grass with a bacterial inoculant on the intake and performance of beef cattle, and studies on its mode of action

This experiment evaluated a bacterial inoculant based on a single strain of Lactobacillus plantarum as a silage additive. Three silages were harvested on 8 September 1989 from the second regrowth of a perennial ryegrass sward, which had received 167 kg N, 28 kg P2O5 and 45 kg K2O ha−1. Mean dry matter (DM) and water soluble carbohydrate concentrations of the herbages at ensiling were 148 g kg−1 and 78 g.(kg DM)−1 respectively. Herbages were treated with either no additive (C), formic acid (3·0 1 t−1) (F) or the inoculant (3·0 1 t−1) (I) and were ensiled in three 80-t capacity silos. For silages C, F and I respectively, pH values were 4·70, 3·77 and 4·47, ammonia-N concentrations were 192, 111 and 182 g (kg total N)−1 and butyrate concentrations were 6·8, 1·8 and 7·1 g (kg DM)−1. The silages were offered ad libitum and supplemented with 2·0 kg concentrates per head daily to thirty-six heifers (mean initial live weight 442 kg). For silages C, F and I, silage DM intakes were 12·7, 14·4 and 14·1 (s.e. 0·42) g (kg live weight)−1, metabolizable energy intakes were 155, 166 and 172 (s.e. 5·1) kJ (kg live weight)−1, and estimated carcass gains were 456, 519 and 518 (s.e. 28·1) g d−1 respectively. A further 18 similar cattle were used in studies on the digestibility of the silages, and rumen degradation of each was estimated with three mature cattle. Inoculant treatment significantly increased crude fibre (P <0·01), neutral detergent fibre (P <0·01), modified acid detergent fibre (P <0·01), hemicellulose (P <0·05) and N digestibilities (P <0·05) and tended to increase N retention from the total diet. It is concluded that although treatment of herbage that was difficult to ensile with the inoculant did not improve silage fermentation, it significantly increased digestibility, especially of the fibre fractions, and silage DM intake and tended to increase animal performance to levels similar to those achieved with a well preserved formic acid-treated silage. Increases in silage DM and metabolizable energy intakes are likely to have been attributable to the effects of the inoculant on digestibility, especially of the fibre fractions.

The selection of winter wheat varieties for whole-crop cereal conservation

Ten commercial varieties of winter wheat were sampled at different stages of growth, and dry mailer (DM) yields and potential nutritional quality, as determined by modified acid detergent fibre concentration (MADF), were measured. Maximum yields for the different varieties were spread over a four-week period, when the DM content was above 350 g kg−1. When the varieties were harvested for conservation as either fermented (DM 380 g kg−1) or alkaline (DM 580 g kg−1) whole crop, the mean MADF concentration was similar at both harvests, with large differences recorded between varieties. At both harvests the quality of the crops was sharply increased by raising the cutting height from 10 to 40 cm above ground level.

Chemical Composition and Energy Value of Maize Silage Made on Farms in England and Wales 1984-92

The chemical composition of 960 samples of maize silage, made on commercial farms in England and Wales between 1984-1992, is described. The average composition was 302 g/kg dry matter (d.m.), pH 3·78, ammonia-N 60 g/kg N, 87 g/kg d.m. crude protein (CP), 292 g/kg d.m. modified acid detergent fibre (MADF), 678 g/kg d.m. neutral-detergent cellulase digestible organic matter (NCDG) and 301 g/kg d.m. starch. The predicted mean metabolizable energy content was 10·5 MJ/kg d.m. There was significant year-to-year variation for each variable. Ammonia-N and ash contents were negatively correlated and starch and metabolizable energy content were positively correlated with silage d.m. content. The results indicated that in recent years maize silage has consistently been made with d.m. contents above 300 g/kg, which should produce little or no effluent, and will lead to high silage intakes by animals.

Effects of inoculant application to silage immediately prior to feeding to young growing cattle on silage intake, digestibility and rumen volatile fatty acid concentrations

In a series of production studies undertaken at this Institute with growing and finishing beef and dairy cattle an inoculant based on a single strain of Lactobacillus plantarum ,when applied to easy and difficult-to-ensile herbage, has produced considerable benefits in terms of silage intake and animal performance without any apparent improvement in silage fermentation. More recently detailed studies have shown that treatment of herbage at ensiling with the same inoculant has resulted in increased degradability of nitrogen (N) in the rumen, and total tract digestibility of dry matter (DM), organic matter (OM), N, neutral detergent fibre (NDF), and modified acid detergent fibre (MADF). Treatment with the inoculant has also altered rumen volatile fatty acid (VFA) concentrations by increasing rumen propionate and decreasing acetate concentrations.It has been suggested that the effects of inoculant treatment on silage DM intake may be due to the presence of the applied bacteria when they reach the rumen rather than their effects in the silo.

Effects of inoculant application to silage immediately prior to feeding to young growing cattle on silage intake, digestibility and rumen volatile fatty acid concentrations

In a series of production studies undertaken at this Institute with growing and finishing beef and dairy cattle an inoculant based on a single strain of Lactobacillus plantarum ,when applied to easy and difficult-to-ensile herbage, has produced considerable benefits in terms of silage intake and animal performance without any apparent improvement in silage fermentation. More recently detailed studies have shown that treatment of herbage at ensiling with the same inoculant has resulted in increased degradability of nitrogen (N) in the rumen, and total tract digestibility of dry matter (DM), organic matter (OM), N, neutral detergent fibre (NDF), and modified acid detergent fibre (MADF). Treatment with the inoculant has also altered rumen volatile fatty acid (VFA) concentrations by increasing rumen propionate and decreasing acetate concentrations.It has been suggested that the effects of inoculant treatment on silage DM intake may be due to the presence of the applied bacteria when they reach the rumen rather than their effects in the silo.

The composition of first‐cut grass for ensilage in England and Wales from 1988 to 1991

AbstractA total of 2225 samples of herbage, typical of that taken for first‐cut silage on commercial farms in England and Wales, was taken between 1988 and 1991. Samples were analysed for dry matter (DM), water soluble carbohydrate (WSC), crude protein (CP) and metabolizable energy calculated from modified acid detergent fibre. The results were used to investigate the effect of weather conditions upon herbage quality for ensilage. In general, in areas of high rainfall, i.e. western areas, herbage DM and WSC were significantly lower than in eastern areas, whilst the reverse situation occurred with CP. Italian ryegrass (IRG) had a significantly higher WSC and lower CP than other grasses, whilst samples from permanent pasture (PP) had significantly lower DM and WSC, and significantly higher CP than other grasses. It was calculated that to produce a WSC concentration in the fresh grass of 37 g kg−1, to produce well‐fermented silage without additive use, IRG grown in the east would require a DM of 160 g kg−1, In contrast PP grown in the west would require a DM content of 250 gkg−1.

Effect of early season sward management on sward quality and lamb liveweight gain during autumn

AbstractIn two experiments (1990 and 1991) perennial ryegrass (cv. Talbot) pasture was subjected to six different management treatments by adjusting stock numbers to achieve set sward heights for set periods between turn‐out in early April and weaning in early July. The main objective of the experiments was to measure the effect of differences in sward management up to July on subsequent sward type, and the effect of sward type on the performance of weaned lambs between mid‐July and early October when all swards were grazed at a sward height of 7 cm. In Experiment 1 swards were grazed at 7 cm initially and then reduced to 3 cm at various dates and maintained at 3 cm until early July. In Experiment 2 swards were grazed initially at 7 cm, and this was reduced to 3 cm and then allowed to return to 7 cm at various dates up to early July.Grazing at a sward height of 7 cm up to weaning, in early July, gave mean twin lamb growth rates of 310 g d−1, while at a tower sward surface height of 3 cm lamb growth rate was reduced to 206 g d−1 The density of seed heads produced from July was strongly influenced by earlier management. Grazing at 7 cm up to July gave a high density of seed heads (213m−2), and this reduced (126 m−2) by grazing to 3 cm. Seed heads were almost eliminated (17 m−2) by grazing at 7 cm until late June followed by grazing down to 3 cm in early July. Reducing sward surface height from 7 cm to 3 cm at an earlier date tended to increase the development of seed heads from early July. Where swards were grazed from 7 cm to 3 cm and then allowed to return to 7 cm, the later in the pre‐weaning period this took place the greater the reduction in seed head development. Greater seed head density was associated with a significant decrease in the nitrogen content of the herbage on offer in Experiment 2, but an increase in modified acid detergent (MAD) fibre content was not significant.Despite the differences in the sward type on offer, the effect on weaned lamb growth rate was small. Lamb liveweight gain during autumn was significantly reduced in Experiment 2 following earlier grazing at 7 cm compared with 3 cm, but liveweight gain differences in Experiment 1 were not significant.

Effects of inoculant treatment on silage fermentation, digestibility and intake by growing cattle

AbstractA changeover design experiment involving thirty‐six 3‐month‐old Friesian male calves (mean initial live weight 127 kg) was carried out to evaluate a bacterial inoculant based on a single strain of Lactobacillus plantarum (Ecosyl, ICI) as a silage additive. On 25–31 August 1988, nine silages were harvested using double‐chop forage harvesters from the second regrowth of three swards, namely permanent pasture which had received 100 kg N ha−1 and perennial ryegrass which had received either 100 or 150 kg N ha−1. Herbages (mean DM and WSC concentrations 144 and 11·2 g kg−1 respectively) from each sward were treated with either no additive, formic acid (2·4 1 t−1) or the inoculant (3·3·1 t−1) and were ensiled in 126 silos of 0·8 t capacity. The only effects of the inoculant on chemical composition of the silages were a decrease in modified acid detergent fibre and an increase in endotoxin and crude and true protein concentrations. Silages were offered ad libitum and supplemented with 1·0 kg of concentrates per head daily for three periods each of 3 weeks in a partially balanced changeover design experiment. Digestibilities of the total diets were determined at the end of the experiment. For the untreated, formic acid‐treated and inoculant‐treated silages, silage dry matter intakes were respectively 3·58, 3·66 and 3·67 (s.e. 0·044) kg d−1, estimated metabolizable energy (ME) intakes were 46·1, 46·7 and 47·1 (s.e. 0·44) MJ d−1, energy digestibilities were 0·727, 0·727 and 0·738 (s.e. 0·0046) and organic matter digestibilities were 0·770, 0·771 and 0·788 (s.e. 0·0042). Rumen degradabilities of the silages were determined using two rumen‐fistulated cows. Mean dry matter and nitrogen degradabilities for the control, formic acid‐treated and inoculant‐treated silages, assuming an outflow rate of 0·05 h−1, were 10·508, 0·49, 0·491 and 0·702, 0·676 and 0·729. It is concluded that the inoculant significantly increased the digestibility of the silages but did not affect dry matter or ME intake.

The effects of incorporating sugar‐beet pulp with herbage at ensiling on silage fermentation, effluent output and in‐silo losses

AbstractThree studies were undertaken with the aim of examining in‐silo losses associated with ensiling mixtures of beet pulp and herbage. In Experiment 1, first‐regrowth perennial ryegrass was ensiled untreated or mixed with either 40 or 120 kg unmolassed beet pulp t−1 fresh grass prior to ensiling. In each of Experiments 2 and 3, second‐regrowth ryegrass was ensiled untreated or mixed with either 40, 80 or 120 kg unmolassed beet pulp t−1 fresh grass prior to ensiling. Dry‐matter concentrations of herbage ensiled in Experiments 1, 2 and 3 were 141, 157 and 139 g kg−1 respectively.Time‐course studies indicated a more rapid fermentation with the untreated silages. Ensiling beet pulp with herbage resulted in significant improvements in silage fermentation, reflected in reductions in silage pH and ammonia nitrogen concentrations, with these effects being pronounced at beet pulp inclusion in excess of 80kg t−1. Beet pulp inclusion increased the dry‐matter concentrations of the resulting silages while reducing crude protein, modified acid detergent fibre and gross energy concentrations. In Experiment 1 beet pulp retained 1·62 and 1·641 effluent kg−1 at the 40 and 120kg t−1 application rates respectively. In Experiments 2 and 3, effluent retentions were 1·40, 1·29 and 0·93 1 kg−1 and 2·87, 2·19 and 1·781 kg−1 at the 40, 80 and 120kg t−1 beet pulp inclusion rates respectively. In each of Experiments 1 and 3, in‐silo losses were reduced with increasing level of beet pulp inclusion, while in Experiment 2 in‐silo losses were relatively unaffected by treatment. Nutrient losses in effluent were reduced by the inclusion of beet pulp in all three experiments, while nutrient losses in surface waste and invisible nutrient losses tended to increase with higher levels of beet pulp inclusion.It is concluded that the inclusion of beet pulp with herbage at ensiling can result in an improved silage fermentation and a reduction in in‐silo losses, while at the same time retaining considerable quantities of effluent within the silo. However, with herbage dry‐matter concentrations below 160gkg−1, beet pulp inclusion in excess of 120 kg t−1 herbage would be required to eliminate effluent production totally.

Sodium fertilizer application to pasture. 5. Effects on herbage digestibility and mineral availability in sheep

AbstractThe effects of feeding herbages fertilized with 0 (nil), 32 (low), 66 (medium) or 96 (high) kg of sodium per hectare per year to sheep on herbage digestibility and mineral availability were examined. Modified acid detergent fibre (MADF), ash, magnesium (Mg) and phosphorus (P) contents were increased by the application of sodium (Na) treatments, while potassium (K), sulphur (S) and true protein (TP) contents were reduced. Dry matter (DM) and MADF intakes were increased in the low and medium treatments and DM and MADF digestibility increased in all Na‐treated herbages. The medium‐ and high‐sodium treatments increased salivary Na content and Na/K ratio and decreased K content. Blood K content was not affected by treatment. Intake, faecal output, apparent availability, urinary output and balance of Na were increased by the application of Na treatments. Potassium intake, balance, apparent retention and urinary output were increased by the low, unaffected by the medium and reduced by the high sodium treatment. The low and medium Na treatments increased the intake and apparent availability of Mg; Mg balance and apparent retention were increased by all Na treatments. Feeding the Na‐treated herbages increased intakes, apparent availability, balance and apparent retention of Ca, P and total cations.The low and medium Na treatments increased S intake, faecal output and apparent retention. It is suggested that through increasing the balance and apparent retention of minerals, the application of sodium fertilizer to pasture will improve the mineral status of sheep, particularly at the low and medium application rates employed in this experiment.

The effect of sugar beet pulp‐based silage additives on effluent production, fermentation, in‐silo losses, silage intake and animal performance

AbstractFirst‐harvest direct‐cut, double‐chopped grass (190 and 164g DMkg−1 in Experiments 1 and 2 resptectively) was ensiled without an additive or, in Experiment 1, with 30 kg t−1 grass of an absorbent additive based on sugar beet pulp (Sweet ‘n’ Dry) or with 3·441 t−1 grass of formic acid and, in Experiment 2, with 30, 50 and 70 kg t−1 grass of Sweet ‘n’ Dry or with 50kg t−1 grass of unmolassed sugar beet pulp. The preservation and nutritive value of the silage, in‐silo losses (including silage effluent production), silage intake and animal performance of adult and growing cattle were examined.In Experiment 1 all three silages were well preserved, although the formic acid‐treated silage displayed significantly lower pH, ammonia nitrogen (NH3N) [g kg−1 total nitrogen (TN)] and volatile fatty acids (VFAs) than the other two silages. In Experiment 2 absorbent‐treated silages displayed significantly lower pH, buffer capacity (Bc), NH3N (gkg−1 TN), CP, modified acid detergent fibre (MADF) and VFAs than untreated silage.Treatment of grass with the absorbent additives at ensiling resulted in reduced effluent production. In Experiment 1 each kilogram of Sweet ‘n’ Dry retained approximately 11 effluent, and in Experiment 2 silages made with Sweet ‘n’ Dry applied at 70kgt−1 and sugar beet pulp applied at 50 kg t−1 produced similar volumes of effluent and each kilogram of absorbent retained 1·0 and 1·31 of effluent respectively.In Experiment 1 sixty beef cattle [mean initial live weight (LW) 460 kg] were grouped according to LW and allocated to treatment at random. For untreated silage (unsupplemented or with 1 or 2 kg supplement head−1 day−1), absorbent‐treated silage (unsupplemented or with 1 or 2 kg supplement head−1 day−1) and formic acid‐treated silage (1 kg supplement head−1 day−1) the daily silage DM intakes were 6·12, 6·21, 6·40, 7·65, 7·45, 7·11 and 7·85 (s.e. 0·280) kg respectively, the daily liveweight gains were 0·22, 0·56, 0·81, 0·59, 0·74, 0·81 and 0·75 (s.e. 0·071) kg respectively and daily carcass gains were 0·31, 0·47, 0·67, 0·47, 0·61, 0·70 and 0·57 (s.e. 0·043) kg respectively throughout a 75‐day feeding period.In Experiment 2, fifty‐six growing cattle (mean initial weight 312 kg) were grouped according to LW and allocated to treatment at random. For untreated silage (unsupplemented or with 1·5 kg Sweet ‘n’ Dry or 1·5 kg commercial concentrates head−1 day−1), silage treated with Sweet ‘n’ Dry at 30, 50 and 70 kg t−1 grass and silage treated with 50kg sugar beet pulp t−1 grass the daily silage DM intakes were 5·46, 5·28, 5·33, 6·21, 6·27, 6·60 and 6·62 (s.e. 0·154) kg respectively and daily liveweight gains were 0·39, 0·75, 0·81, 0·63, 0·76, 0·94 and 1·75 (s.e. 0·052) kg respectively throughout a 122‐day feeding period. In this experiment 360g kg−1 more absorbent was required when it was included at ensiling rather than offered as a supplement to untreated silage to achieve the same individual animal performance.

Effect of genotype on the morphological characteristics, chemical composition and feeding value of nine barley straws, and responses to soya-bean meal supplementation

AbstractThree experiments were conducted to investigate the effect of genotype on the morphological characteristics, chemical composition and feeding value of nine chopped barley straws, and responses of the feeding value to a supplement of soya-bean meal (SBM). In experiment 1, the straws were offered ad libitum to 12 wethers and measurements were made of straw intake and dry (DMD) and organic (OMD) matter digestibility using a balanced lattice design with three periods. Experiment 2 used the same experimental design but the straws were offered ad libitum with 200 g SBM. Experiment 3 measured the dry matter losses (DML) of ground straws from nylon bags placed in the rumen of three wethers. The extent (b) and rate (c) of DML were estimated using the equation DML = a + b(l – ect).There were significant differences in the stem height (P &lt; 0·001), leaf proportion (P &lt; 0·001), and protein (P &lt; 0·001) and modified acid detergent fibre (P &lt; 0·01) concentrations between the straws. Significant (P &lt; 0·05) effects of genotype on intake were seen but the variation in intake between them decreased when the protein supplement was added. Effects of genotype on DMD (P &lt; 0·05) and OMD (P &lt; 0·05) were seen in unsupplemented straws and differences of OMD (P &lt; 0·05) were still apparent when SBM was given with straw. Although there were significant (P &lt; 0·05) differences in DML after 48 h incubation, the constants b and c were similar (P &gt; 0·05) across the genotypes. Protein concentration in the straw, although closely correlated with intake, appears to have less value as a predictor of feeding value than previously thought.