Silage Intake Research Articles

Grass silage as a basic feed for store lambs. 3. Effect of barley supplementation of silages varying in chop length on silage intake and lamb performance

AbstractAn experiment was carried out to study the effect of silage chop length and barley supplementation on silage intake and the performance of store lambs. The silages were cut from a perennial ryegrass regrowth at a relatively mature stage of growth in early July. Different types of harvester were used to produce a long silage (L), single‐chopped (S), double‐chopped (D), medium precision‐chopped (MP) or a short precision‐chopped (SP) silage. The chop length of the silages averaged 37.4, 12.4, 8.4, 7.0 and 2.9 cm respectively. All silages were treated with formic acid at 2.51 t−1grass. They were well preserved and of a good quality with a dry‐matter (DM) digestibility of 720–760 g kg−1 DM. The silages were fed ad libitum to Suffolk crossbred store lambs over a period of 10 weeks. Each silage was fed either alone or was supplemented with whole barley at 400 g lamb−1 d−1.When offered silage alone, intakes were 738, 679, 773, 980 and 910 (± 30) g DM d−1 for silages L, S, D, MP and SP respectively. Similar relative differences in intakes between the silages were evident when supplemented with barley. Liveweight gain on silage alone was higher on the precision‐chopped silages (85–93 g d−1) than the long or flail‐chopped silages (28–49 g d−1). Liveweight gain on the precision‐chopped silages was also better when supplemented with barley (150 vs. 90–112 (± 90) g d−1). Silage intake and lamb performance were similar for the MP and SP silages, despite the difference in chop length.Barley supplementation reduced silage intake to a similar extent for all silages (‐9%) and increased total DM intake (+ 30%) and metabolizable energy intake (+ 37%). The substitution rates of silage for barley were similar for all silages and averaged 0.24 g silage DM g−l barley DM. The response in weight gain per 100g of barley fed was similar for all silages and averaged 20.0 g liveweight gain and 13.4 g carcass gain. Feed conversion efficiency of the total diet was similar for the Mail‐chopped and precision‐chopped silages but was less for the long silage.The results of this study show that the benefit in weight gain due to the higher intake of precision‐chopped silage was maintained when the silage was supplemented with a moderate level of barley. Such silage required supplementation with barley (400 g d−l) to achieve a rate of liveweight gain of 150g d−1.

Effects of protein supplementation of grass silage on the performance and carcass quality of beef cattle

SUMMARYTwo experiments (E1 and 2) were carried out in Northern Ireland in 1988/89 to examine the effects of a wide range of supplementary protein intakes given with grass silage-based diets on the performance and carcass composition of beef cattle, and to compare diets based on silage and dried forage. The five treatments used consisted of grass silage offered ad libitum and supplemented with 2·5 kg dry matter (DM) of barley-based concentrates containing (1) zero, (2) 0·2, (3) 0·4 and (4) 0·6 extracted soyabean meal and (5) artificially dried grass and hay supplemented with 3·3 kg concentrate DM. Experiments E3 and 4 were carried out in 1991/92 to examine the responses in ration digestibility, silage intake and animal performance to supplementary protein in relation to the requirements recommended by the United Kingdom Metabolizable Protein System. The two treatments consisted of grass silage offered ad libitum and supplemented with 3·2 kg DM of (1) barley and (2) 0·8 barley and 0·2 soyabean meal. The silages used were well preserved, containing on average 200 g DM/kg; 143 g crude protein (CP)/kg DM; 79 g ammonia-N/kg total N and 734 g digestible organic matter/kg DM. The cattle were castrated males of medium to late-maturing breed type and were initially 13 months old and 396 kg liveweight. Increasing protein intake did not affect ration digestibility, silage DM intake or animal performance in any of the four experiments, despite the fact that the effective rumen degradable protein (ERDP) intakes in the diets supplemented with barley alone were only 80–85% of ERDP requirements. However, increasing protein intake tended to increase carcass fatness in all experiments, the effect being significant (P < 0·05) for the lipid concentration in the M. longissimus dorsi muscle in E1 and 2. Offering the dried forage-based diet rather than an isonitrogenous silage-based diet did not affect carcass fatness. It is concluded that supplementing well preserved grass silages with mixtures of barley and soyabean meal, rather than with barley alone, did not affect ration digestibility, silage intake or animal performance but tended to increase carcass fatness, especially marbling fat, despite the fact that ERDP intakes for the diets with the lowest protein concentration were only 80–85% of requirements given by the United Kingdom Metabolizable Protein System.

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.

Response of growing steers to diets containing big bale silage and supplements of molassed sugar beet pulp with and without white fish meal

Twenty four steers, either Limousin ♂ or Simmental ♂ × (British Hereford ♂ × Friesian ♀) ♀ genotype were used in a 77 day study. Initial mean live weights were 288 kg and the steers were allocated by randomised block design to one of four treatments. The treatments were big bale silage fed alone ad libitum (C) or supplemented (kg dry matter (DM) day −1) with molassed sugar beet pulp (MSBP) 0.66 (S), 0.66 MSBP + 0.12 white fishmeal (FM) (SF1) or 0.66 MSBP + 0.23 FM (SF2). The silage (292 g DM kg −1) was of moderate fermentation quality and contained an estimated 9.7 MJ Metabolisable Energy and 93 g crude protein kg −1 DM. Supplementation with MSBP alone or together with FM significantly reduced silage DM intake although there was evidence of a reduction in the magnitude of this effect due to FM supplementation. MSBP supplementation alone did not increase live-weight gain but supplementation with FM significantly increased live-weight gain with no significant differences observed between diets SF1 and SF2. Food conversion ratio was non-significantly improved by MSBP alone, with further significant improvements due to FM. None of the supplementary treatments significantly improved apparent digestibility of organic matter or nitrogen (N). N intake was significantly elevated by FM supplementation which was associated with trends towards a greater N retention and significant increases in rumen ammonia and volatile fatty acid (VFA) and blood plasma urea concentrations. Molar proportions of rumen VFA were not altered by treatment. There was a trend towards an improvement in rumen microbial protein synthesis estimated by purine derivative excretion only on Diet SF2. This result coupled with the trends towards increases in silage intake may suggest some improvement in digestive activity. In addition a major anabolic effect of FM supplementation of the diets may have occurred post-absorptively and may relate to the supply of, for example, essential amino acids. The results indicated that moderate growth performance (0.6 kg day −1 LWG) can be achieved with diets based on big bale silage with low crude protein concentrations of 95–100 g kg −1 DM which were improved by supplementation of MSBP with FM. The interaction between big bale silage and MSBP and N sources and levels needs further investigation.

Rapeseed meal, maize-gluten feed and fish meal as protein supplements for maize silage given to growing/finishing Limousin × Holstein Friesian bulls

AbstractIn each of three experiments, 60 Limousin × Holstein Friesian bulls, initially of 191, (s..e. 5·0), 177 (s.e. 5·5) and 210 (s.e. 7·2) kg mean live weight for experiments 1, 2 and 3 respectively, were offered maize silage ad libitum plus one of three barley-based, isonitrogenous compound diets containing 200 g rapeseed meal, 575 g maize-gluten feed or 100 g fish meal per kg fresh weight. Compound diets were given at the rate of 3·0 kg (fresh weight) per head per day up to 320 kg live weight and at 3·3 kg per head per day from 320 kg to 420 kg live weight. In experiment 3, when bulls were taken through to slaughter, the compound diet was further increased to 3·5 kg per head per day from 420 kg live weight to slaughter. Experiments 1 and 2 were conducted over 128 and 194 days, with mean live weights at the end of the experiments of 347 (s.e. 17·2) and 414 (s.e. 24·2) kg respectively. In experiment 3, bulls were slaughtered at 16 months of age at a mean live weight of 544 (s.e. 25·0) kg.In experiment 1, the fish-meal diet gave the highest rate of daily live-weight gain at 1·34 compared with 1·17 and 1·16 (s.e.d. 0·041) kg for rapeseed-meal and maize-gluten diets, respectively. In experiments 2 and 3, daily gains were similar on all treatments at 1·21, 1·19 and 1·26 (s.e.d. 0·036) kg and 1·06, 1·09 and 1·11 (s.e.d. 0·035) kg for the rapeseed-meal, maize-gluten and fish-meal diets respectively. Total daily dry-matter intakes did not show consistent trends: in experiment 1, intakes were 5·8, 5·6 and 5·8 kg/day, in experiment 2, 6·2, 6·2 and 6·3 kg/day; and in experiment 3, 7·1, 7·3 and 7·1 kg/day for rapeseed-meal, maize-gluten and fish meal, respectively. The higher intakes of dry matter in experiment 3 were due to the greater intakes of maize silage by bulls taken to heavier weights in this experiment.

The influence of ammonia, biogenic amines and γ-aminobutyric acid on grass silage intake in sheep

We investigated whether biogenic amines alone, or a combination of NH3, amines and gamma-aminobutyric acid (GABA) influenced grass-silage intake, intake behaviour and rumen liquid content in sheep. Three diets were studied: a grass silage preserved with formic acid (4 litres/tonne) (FAS), FAS with 4.9 g amines/kg DM added (FAS+A), and FAS supplemented with a combination of N-components at the following concentrations: 2.7 g amines, 3.0 g NH3 and 5.0 g GABA/kg DM (FAS+C). The diets were offered ad libitum, once daily to six rumen-cannulated Texel wethers in a crossover design. Daily DM intake (DMI; g DM/d) tended to be influenced by diet (P = 0.08). The DMI of FAS+A was similar to that of FAS alone, whereas that of FAS+C tended to be higher. The mean rate of ingestion (g DM/min) over all feeding bouts tended to be the lowest for FAS+A (P = 0.06). No differences were found among the diets concerning intake behaviour during the principal meal. Average intake rate of the small meals tended to be the lowest for FAS+A (P = 0.06). Although rumen NH3 concentration was higher (P < 0.05) after the principal meal, rumen pH, osmolality, rumen pool size and liquid content were not significantly altered by adding amines or the mixture of N-components to FAS. We conclude that biogenic amines or N-containing products of protein fermentation in concentrations normally found in poor-quality silages do not reduce the intake of well-preserved formic acid-treated silage. A direct effect on chemostatic regulation of intake was not observed, but a slight negative effect on silage palatability cannot be excluded.

A comparison of oak browse ( Quercus spp.) and silages of rye and maize with respect to voluntary intake, digestibility, nitrogen balance and rumination time in penned Korean sika deer

Two experiments were conducted to compare the voluntary feed intake, apparent digestibility, nitrogen (N) balance and rumination time of oak browse and different silages as roughage sources of sika deer to look into the possibility of feeding silages instead of oak browse which is in short supply and expensive in Korea. In Experiment 1, three sika deer with average body weight of 44.3 kg were fed three different roughages (oak browse, untreated rye silage, and formic acid treated silage) in a 3 × 3 Latin square design. Experiment 2 was conducted using four sika deer averaging 44.0 kg in body weight. They were fed four different experimental roughages (oak browse versus three different silages produced from maize of milk stage, dough stage, and yellow stage of maturity) in a 4 × 4 Latin square design. All the experimental animal were fed 0.5 kg of concentrate per day in addition to the experimental roughages. Intakes of dry matter, organic matter, crude protein and neutral detergent fiber were higher for oak browse than those for rye and maize silages in Experiments 1 and 2, respectively. Apparent digestibility of all nutrients was significantly ( P < 0.001) higher for the rye and maize silages than for the oak browse. Due to the differences in nutrient digestibility, total amounts of nutrient digested were significantly ( P < 0.001) higher for the rye and maize silages than oak browse. Fecal N excretion was significantly higher ( P < 0.001) for the oak browse than for the rye and maize silages, with no difference between the silages. However, urinary N excretion was higher with rye and maize silages compared with that for the oak browse. Sika deer fed rye and maize silages had significantly higher ( P < 0.001) N retention than animals on oak browse. Times spent ruminating were not significantly different among diets in both experiments. The results indicate that oak browse may be replaced with either rye or maize silage roughage sources for sika deer.

The effect of fine grinding or sodium hydroxide treatment of wheat, offered as part of a concentrate supplement, on the performance of lactating dairy cows

AbstractA study was conducted to examine the effect of fine grinding or sodium hydroxide treatment of wheat, and increasing concentrate food level, on milk production. Two concentrates based either on ground wheat (450 g/kg, GW) or sodium hydroxide treated wheat (500 g/kg, SW) were offered at four concentrate levels of 2·5, 5·0, 7·5 and 10·0 kg dry matter (DM) per day to 24 dairy cows in a three-period, change-over design experiment. On average, across all concentrate food levels, silage DM intake was significantly (P &lt; 0·01) higher with the SW concentrates, reflecting a significantly lower silage substitution rate with SW relative to GW concentrates (P &lt; 0·01). Milk yield was also significantly higher with the SW concentrates (P &lt; 0·05), although marginal responses to increased concentrate food level were similar (P &gt; 0·05). Milk protein concentration increased linearly with increasing concentrate food level (P &lt; 0·001), with a significantly greater response with the GW relative to the SW concentrate (0·59 v. 0·24 g/kg (P &lt; 0·05) increase per kg additional concentrate). However, milk protein concentration was also significantly lower with the GW concentrate at low food levels (P &lt; 0·05). Milk fat concentrations were similar with the two concentrate types with significant reductions in milk fat concentration with increasing concentrate food level (P &lt; 0·05). Blood urea (P &lt; 0·001) and β-hydroxybutyrate (P &lt; 0·05) concentrations were significantly lower in animals offered the SW concentrate. Apparent digestibility coefficients were unaffected by either concentrate type or concentrate food level (P &gt; 0·05), although modified acid-detergent fibre apparent digestibility was significantly reduced with increasing concentrate food level (P &lt; 0·001). Results indicate that, at similar levels of concentrate feeding, silage intake and milk yield were significantly greater with SW compared with GW concentrates (P &lt; 0·05 or greater). Increases in milk protein concentration with increasing concentrate food level were significantly greater with GW than with SW concentrates (P &lt; 0·05).

Effects of physical treatment of barley and rapeseed meal in dairy cows given grass silage-based diets

Twenty-four Ayrshire cows were used to study the effects of physical treatment of barley, rapeseed meal (RSM) supplementation and heat-moisture treatment of RSM on silage intake and milk production. Experimental design was a cyclic change-over with six dietary treatments. The treatments in a 2 x 3 factorial arrangement consisted of either untreated (UB) or heat-moisture treated barley (TB), given without protein supplementation (control) or with untreated or heat-moisture treated RSM. Grass silage was given ad libitum and the concentrates at a rate of 10 kg/d. For the RSM diets, 2 kg/d of the basal concentrate was replaced with either untreated or treated RSM. Treatment of barley decreased silage intake, the effect being greater when the supplement did not contain RSM. There was no effect on milk yield, but due to the lower milk fat content, energy corrected milk yield was lower in cows given TB than in those given UB. Feeding the TB diets was also associated with lower milk urea content, and with increased milk protein content but not protein yield. Faster initial rate of gas production in vitro suggested that the treatment of barley increased the rate of fermentation. Compared with the control diets, RSM supplementation significantly increased silage intake, milk yield, milk protein content and yields of all milk constituents. Heat-moisture treatment of RSM did not produce any further production response.

The Effect of In-Silo Effluent Absorbents on Effluent Production and Silage Quality

Experimental data on the effects of absorbent inclusion in the silo on effluent production and silage quality is reviewed. The absorbent materials used in various studies include straw, hay, paper, bentonite, polymers, cereals, dried sugarbeet pulp, various by-products and compound feeds formulated to reduce effluent and enhance silage quality. Most studies have shown absorbent inclusion (20–80 kg/t) to reduce total effluent production by 20–85%. The amount of effluent retained per unit of absorbent varied widely for different absorbents and for the same absorbent in different experiments. This variation cannot be attributed simply to differences in experimental procedures and implies that crop characteristics such as proportion of stem, amount of surface water, etc. influence the effectiveness of absorbents. Highly lignified materials (hay, straw, newspaper) and absorptive minerals (bentonite), though highly absorptive, adversely affect nutritive quality and are unlikely to find application in current conservation systems. The inclusion of cereals in the silo has generally improved fermentation and nutritive quality but their effectiveness as absorbents is questioned in several experiments. Inclusion of dried sugarbeet pulp has almost invariably reduced effluent production although the amount retained has varied widely between experiments. Sugarbeet inclusion improved fermentation and reduced losses when the untreated grass was poorly fermented. Silage quality was improved by sugarbeet inclusion; the overall efficiency of inclusion, compared to supplementary feeding, appears to depend on the extent to which sugarbeet inclusion influences in-silo losses and silage intake. The results repeated for proprietary absorbents have been generally similar to those for sugarbeet. The evidence available suggests that incorporation of sugarbeet or proprietary absorbents in the silo would be beneficial, particularly if the untreated crop is likely to be poorly fermented. The main factors mitigating against these or other absorbents is the unpredictability of effluent retention and the additional labour, resources and silo space required at harvest time.

The effects of wilting of grass prior to ensiling on the response to bacterial inoculation. 2. Intake and performance by dairy cattle over three harvests

AbstractFour silages (unwilted with and without inoculant, and wilted with and without inoculant) were prepared from perennial ryegrass swards at each of three harvests over the growing season. The four silages from each of the first (primary growth), second (first regrowth) and third (second regrowth) harvests were offered ad libitum to 48 dairy cows during periods 2, 1 and 3 respectively, in a two (control and additive) × two (unwilted and wilted) × three (harvest (period)) change-over design experiment with 8-week experimental periods. The animals also received a concentrate supplement at 7·0, 6·1 and 5·2 kg dry matter (DM) per day in the first, second and third periods respectively. The supplement was based on barley, molasses and soya-bean meal.There were significant interactions between inoculation and wilting across the three harvests on silage DM intake (F&lt;0-01), milk yield (P&lt;0·05), and outputs of fat (P&lt;0·01) and protein (P&lt;0·05). Inoculation had no significant effects on silage intake and milk production across the unwilted and wilted silages. However, within the unwilted silages, inoculation significantly increased silage DM intake by 0·46 kg/day (P &lt; 0·05) and fat yield by 0·032 kg/day (P&lt;0·05). In contrast, within the wilted silages inoculation significantly reduced fat yield by 0·030 kg/day (P &lt; 0·05). Wilting of grass prior to ensiling significantly increased silage DM intake by 0·73 kg/day (P &lt;0·001), milk yield by 0·42 kg/day (P&lt;0·05), fat yield by 0·053 kg/day (P &lt; 0·001) and protein yield by 0·047 kg/day (P &lt; 0·001) across the inoculant-treated and untreated silages. The effects however were mainly derived from the untreated silages as within the inoculant-treated materials the differences in silage intake and milk yield were not significant between unwilted and wilted treatments. The results of the current experiment indicate that wilting with no additive significantly improved silage intake and milk production, but otherwise the improvement was reduced with wilting following inoculation. Inoculation significantly increased silage intake and fat yield when used with the unwilted grass, but it significantly reduced fat yield when used with the wilted grass.

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.

Milk production from grass silage diets: effects of high-protein concentrates for lactating heifers and cows on intake, milk production and milk nitrogen fractions

AbstractTo examine the effects of increasing the crude protein (CP) content of concentrates at either equal concentrate intake (increasing CP intake) or at reducing concentrate intake (equal CP intake), 44 multiparous Holstein-Friesian cows were allocated to one of five treatments for weeks 4 to 18 of lactation. The treatments were 6 kg dry matter (DM) per day of concentrates containing nominally 200, 300 or 400 g CP per kg DM or 9 or 3 kg DM per day of concentrates containing 200 or 600 g CP per kg DM respectively. In addition 23 first-calf cows (heifers) were offered 5 kg DM per day of concentrates containing 200, 300 or 400 g CP per kg DM. All the animals were offered first-cut perennial ryegrass silagead libitum. Increasing the concentrate CP content at equal intake caused only small and non-significant increases in silage intake by both heifers and cows. It significantly increased yields of milk and milk protein for both groups but whereas the cows responded to both increments of CP, the heifers only responded to the first. The concentrations of total protein, true protein, casein and non-protein nitrogen (NPN) in milk were significantly increased but the concentration of whey protein remained unchanged. Increasing CP concentration while the concentrate ration was reduced enhanced silage intake but had no significant effect on yields of milk or milk solids. The concentrations of total protein, true protein (non-significant), casein and NPN all increased but whey protein was unchanged. Overall the concentrations of casein and NPN were linearly related to the dietary CP concentration. With both concentrate strategies the proportion of true protein in total milk protein decreased and the proportion of NPN increased with increasing dietary CP concentration but the changes, though highly significant, were relatively small. It is concluded that the strategy of reducing the concentrate ration while maintaining concentrate CP intake causes only small reductions in milk solids production but it is dependent for success on supplies of high-quality grass silage to substitute for the concentrates.

The use of near infra-red reflectance spectroscopy (NIRS) to predict voluntary intake of grass silage by lambs and dairy cows

The greatest error in formulating rations is due to the inaccuracy of prediction of silage dry matter intake (SDMI). Until recently, predictions have been based on die method of Lewis (1981) which predicts intake from traditional silage analysis :- dry matter (DM), crude protein (CP), digestible organic matter in the dry matter (DOMD) and ammonia N. Recently, the incorporation of new feed characterisation data, obtained from electrometric titration (ET), has unproved predictions (Offer et al., 199S). A 4 year study has yielded data to evaluate alternative methods for the prediction of SDMI using traditional, ET and HPLC data and spectral information obtained by near infra-red reflectance spectroscopy (NIRS) of fresh and dried samples.

The use of near infra-red reflectance spectroscopy (NIRS) to predict voluntary intake of grass silage by lambs and dairy cows

The greatest error in formulating rations is due to the inaccuracy of prediction of silage dry matter intake (SDMI). Until recently, predictions have been based on die method of Lewis (1981) which predicts intake from traditional silage analysis :- dry matter (DM), crude protein (CP), digestible organic matter in the dry matter (DOMD) and ammonia N. Recently, the incorporation of new feed characterisation data, obtained from electrometric titration (ET), has unproved predictions (Offer et al., 199S). A 4 year study has yielded data to evaluate alternative methods for the prediction of SDMI using traditional, ET and HPLC data and spectral information obtained by near infra-red reflectance spectroscopy (NIRS) of fresh and dried samples.

An examination of the effect of concentrate energy source on milk production of dairy cows offered grass silages with differing intake characteristics

Considerable progress has been made recently at this Institute in improving the accuracy of prediction of silage intake when offered as the sole diet. However in most farm situations, silage is usually supplemented with varying levels and types of concentrate when offered to dairy cattle. The aim of the present study was to examine the effects of concentrate energy source on the voluntary food intake and milk yield and composition of lactating dairy cattle when offered a diverse range of grass silages.A total of five grass silages were used in the study, silages A, B and D were produced from primary regrowths, while silages C and E were produced from second regrowths of perennial ryegrass swards. Silages A, B, C, D and E were ensiled after 48, 24, 0, 0 and 24 hour wilting periods. Silages A and C were ensiled untreated, B and D treated with an inoculant, and silage E treated with a formic acid based additive.

An examination of the effect of concentrate energy source on milk production of dairy cows offered grass silages with differing intake characteristics

Considerable progress has been made recently at this Institute in improving the accuracy of prediction of silage intake when offered as the sole diet. However in most farm situations, silage is usually supplemented with varying levels and types of concentrate when offered to dairy cattle. The aim of the present study was to examine the effects of concentrate energy source on the voluntary food intake and milk yield and composition of lactating dairy cattle when offered a diverse range of grass silages.A total of five grass silages were used in the study, silages A, B and D were produced from primary regrowths, while silages C and E were produced from second regrowths of perennial ryegrass swards. Silages A, B, C, D and E were ensiled after 48, 24, 0, 0 and 24 hour wilting periods. Silages A and C were ensiled untreated, B and D treated with an inoculant, and silage E treated with a formic acid based additive.

The effects of level of concentrate on eating behaviour, predicted hourly nutrient release in the rumen and performance of ewes fed grass silage

Recent work has reported that synchronising the hourly supply of energy and nitrogen to the rumen can improve the efficiency of microbial growth by 12-14% (Sinclair et al., 1995). However, animals when offered an asynchronous feed ad-libitum may alter their pattern of intake to achieve a more synchronous release of nutrients in die rumen. In addition, the provision of concentrates at fixed times may alter the hourly and daily intake of forage and the pattern of release of nutrients in the rumen. In a previous experiment with growing sheep (Sinclair and McQuiston 1995), grass silage was demonstrated to have an asynchronous release of energy and nitrogen in the rumen and mat the provision of concentrates did not alter the pattern of silage intake but increased the degree of synchrony.

The effects of level of concentrate on eating behaviour, predicted hourly nutrient release in the rumen and performance of ewes fed grass silage

Recent work has reported that synchronising the hourly supply of energy and nitrogen to the rumen can improve the efficiency of microbial growth by 12-14% (Sinclair et al., 1995). However, animals when offered an asynchronous feed ad-libitum may alter their pattern of intake to achieve a more synchronous release of nutrients in die rumen. In addition, the provision of concentrates at fixed times may alter the hourly and daily intake of forage and the pattern of release of nutrients in the rumen. In a previous experiment with growing sheep (Sinclair and McQuiston 1995), grass silage was demonstrated to have an asynchronous release of energy and nitrogen in the rumen and mat the provision of concentrates did not alter the pattern of silage intake but increased the degree of synchrony.

Control of voluntary intake of precision-chopped silages by ruminants: a review

The aim of this review is to provide a better understanding of the ways in which ruminants control their voluntary intake of finely-chopped silages. Silages with an excellent conservation quality can be ingested at similar levels to the corresponding fresh or dry forages. Intake levels decrease when conservation quality decreases. The implicated physiological mechanisms for this phenomenon are discussed in this review. Poorly preserved silages may have low palatibility, decreasing the animal's motivation to ingest. At the ruminal level, the physical control of intake is generally not involved. On the other hand the fermentation products present in silage seem to induce a high and rapid level of satiation, out of proportion to their relatively low quantity. At the metabolical level some limiting factors may also exist (eg, a poor balance between amino acids and energy, and high levels of acids to be metabolized). Fermentation products induce most of the observed reactions. For well-preserved silages, high quantities of lactic and acetic acids limit intake. Their effects seem to be additive, which explains the observation that low pH often has a negative action. The negative effect of moisture is generally strengthened by that of the acids. For poorly-preserved silages, products of protein decomposition must be considered in addition to volatile fatty acids. The effect of N-compounds is less clearly explained than that of acids. For example, ammonia alone generally seems to have no direct effect. However it is clear that N-compounds taken together have a negative effect on appetite. It can be concluded that the negative effects of poor quality silages are multifactorial; each fermentation product alone has a low effect, but the sum of all the components must be considered. Moreover, it is apparent that some physiological mechanisms are used to control silage intake, which explains the complexity of the studies on this subject.