The effect of system of silage harvesting and feeding on milk production

Two silages were produced by harvesting grass either unwilted, using a direct cutting flail forage harvester (flail-direct), or wilted following precut-ting and being picked up using a meter-chop harvester (precision-wilted). Formic acid was applied at the rates of 2·45 and 2·9 1 t^-1 for the flail-direct and precision-wilted silages, respectively. Weather conditions were difficult, both before and during harvesting with a total of 27 mm rainfall falling on the wilted herbage before ensiling. The in-silo dry matter losses were 199 and 68 g kg^-1 for the flail-direct and precision-wilted silages, respectively. The resulting silages had mean particle lengths of 49 and 24 mm, dry matter contents of 186 and 276 g kg-^-1 and D-values of 068 and 062 for the flail-direct and precision-wilted silages, respectively. During a 141-day feeding period commencing on 19 November, the two silages were offered to 88 British Friesian cows with a mean calving date of 21 January and divided into four groups in a 2×2 factorial design experiment. The silos were divided longitudinally and two groups of cows were self-fed the silages in situ, one for each silage type, while the other two groups were easy-fed the same silages along a feed fence. There were no significant interactions between system of silage harvesting and feeding on any of the measurements of animal performance. Animals on the flail-direct silage consumed 16% less silage dry matter and produced 10% more milk per cow than those on the precision-wilted silage treatment. The overall effect was a 12% greater milk output for each unit of grass dry matter ensiled with the flail-direct than with the precision-wilted harvesting system. System of silage feeding did not significantly influence silage intake or milk output, with the mean milk yields during the final 21 days of the study being 234 and 236 kg d^-1 (±0.30) for the self- and easy-feed systems, respectively. The effects of the treatments on milk composition, liveweight change, body condition score and total ration digestibility are also reported.     

An evaluation through lactating cattle of a bacterial inoculant as an additive for grass silage

Three silages were prepared from herbage treated with either an inoculant (Ecosyl, Imperial Chemical Industries plc) at 3.21 t^?1, formic acid (850 g kg^?1, Add F BP Chemicals International Ltd) at 2·3 1 t^?1, or no additive (control). The herbage used was the first regrowth from perennial ryegrass swards. It was ensiled unwilted, and had mean dry matter and water soluble carbohydrate concentrations at ensiling of 154 and 24·1 g kg^?1 respectively. Time course studies showed only minor effects of additive treatment on fermentation patterns within the silo and all three silages had good fermentations. Over an 88 d feeding period, commencing on day 7 of lactation, forty-eight British Friesian cows were used to evaluate the silages in a three-treatment, randomized-block design experiment. The animals were stalled individually, offered the silages ad libitum, and in addition received 5 kg d^?1 of a supplement containing 196 g kg^?1 crude protein. On the basis of the data recorded during the final 28 d on treatment the animals receiving the inoculant-treated silage consumed 12 and 10% more silage dry matter and produced 2·1 and 2·3 kg d^?1 more milk than those given the control and formic acid-treated silages respectively. Over the total experimental period the milk yields were 1957, 1894 and 2094 (±41·3) kg for animals receiving the control, formic acid- and inoculant-treated silages respectively. Animals offered the formic acid treated silage produced milk of significantly higher fat concentration than those given the other two silages. Total ration digestibility studies, conducted with three cows per treatment, indicated no significant differences in digestibility coefficients, nitrogen utilization or metabolizable energy concentrations of the three treatment diets. It is concluded that the higher milk yield recorded with the inoculant-treated silage, and the higher milk fat concentration with the formic acid-treated silage, over that obtained with the control silage, were due to the increases in ME intake of 5 and 16 MJ d^?1 for the formic acid and inoculant-treated silages respectively.     

The influence of the system of silage harvesting and feeding and the use of protected protein on milk production

The study compared two systems of silage harvesting, direct-cutting flail harvesting (flail-direct) or pre-cutting, followed by wilting and collection by a meter-chop harvester (precision-wilted). Each silage was self or easy fed to dairy cows. In addition, the response to protected soya bean meal included in the supplementary concentrate was also examined. Approximately 400 t of each of the two silages were produced from the same swards under good weather conditions with formic acid applied as an additive. The resulting silages were well preserved and had mean particle lengths of 43 and 29-mm, and D-values of 0-74 and 0-71 for the flail-direct and precision-wilted silages, respectively. During a 159-d feeding period commencing on 5 November, the silages were offered to 88 British Friesian cows in a 2³ factorial design, continuous feeding experiment. The cows calved during the experiment and had a mean calving date of 18 January. The feeding treatments involved both silage types, two systems of silage feeding (self and easy) and two sources of protein in the supplementary concentrate given after calving (soya bean or 100 g kg^-1 protected soya bean). No concentrates were offered pre-calving and all animals were given 7.6 kg d^-1 concentrates post-calving. There were no significant interactions between the system of silage harvesting and feeding. Animals on the precision-wilted silage consumed 14% more silage dry matter (10.9 vs. 9.6 kg DM d^-1) over the total period and by the end of the experiment were producing 7% less milk per day (25.4 vs. 27.2 kg). However, the responses in the output of total milk constituents (fat and protein) were lower than those obtained in milk yield. Animals offered silage by self feeding had similar dry matter intakes, but produced marginally less milk than those easy-fed. Ration digestibility and nitrogen utilization data, obtained from a concurrent change-over design experiment, suggested that the energy from the precision-wilted silage was less efficiently utilized for milk production. There was no significant response in either milk yield or composition to the inclusion of protected soya bean in the supplement.     

Effects of the type of additive and the type of supplement on the utilization of grass silage for milk production in dairy cows

Four silages were prepared from grass treated with additives designed to produce different extents of fermentation in the silo. The additive treatments were: formic acid at 5 l t^?1; a bacterial inoculant (Ecosyl, ICI plc); the inoculant plus molasses at 20 kg t^?1; and a noadditive control. All silages were well preserved. Formic acid severely restricted the extent of fermentation, the concentration of lactic acid being only 50% of that seen for the other treatments, all of which were similar in lactic acid concentrations. The silages were offered ad libitum, either as the sole component of the diet or together with three supplement treatments to 16 British Friesian cows, in four 4 treatment × 4 period Latin squares with periods of 28 d duration. The supplements were: a barley-based mixture at 5 kg d^?1 (B); a high-fat, high-protein product at 2 kg d^?1 (FPI) and at 3 kg d ^?1 (FP2); both FP treatments were given with 1 kg d^?1 of molassed sugarbeet pulp. A preliminary experiment, using three lactating, rumen-cannulated cows in a 3×3 Latin square design with 28-d periods, provided information on rumen digestion when the supplements were given with a separate, non-experimental silage. In the preliminary experiment, neither of the FP treatments influenced the molar proportion of the major rumen volatile fatty acids compared with treatment B; nor were there any depressive effects of the FP treatments on silage intake compared with treatment B. In the main experiment, the intake of silage with the inoculant treatment was less than that with the other treatments, the effect being generally significant (at least P<0·05) for all three supplements. When the silages were given unsupplemented, there were differences in the concentration (P<0·001) and yield (P<0·01) of milk fat, both of which were lowest for the no-additive control and highest for the formic acid silage. When supplement B was given, the concentration and yield of milk fat were lowest for the no-additive control and the concentration and yield of milk protein were highest for the formic acid silage. For all silages both FP treatments tended to depress silage intake and reduce the concentration of fat and protein in milk compared with treatment B. Although there were clear indications of differences in nutritional characteristics between the silages, there was little evidence that the differences between silages influenced the responses to changes in the composition of the supplements.     

Effects of addition of lactic acid and post-ruminal supplementation with casein on the nutritional value of grass silage for milk production in dairy cows

Two levels of lactic acid were added to a well-preserved silage to give silages with three concentrations of lactic acid: 53 (control), 96 (LA-50) and 134 (LA-100)g (kg DM)^-1. These silages were given ad libitum with 5 kg d^-1 of a mixture of barley and soya-bean meal (75:25) to six lactating dairy cows in a 6 × 6 Latin square design experiment to examine the effects on silage intake and milk production of the addition of lactic acid, both with and without a post-ruminal supplement of 230 gd^-1 sodium caseinate. The six treatments were (1) control silage without casein, (2) control silage plus casein, (3) LA-50 silage without casein, (4) LA-50 silage plus casein, (5) LA-100 silage without casein and (6) LA-100 silage plus casein. Sodium caseinate was administered as a continuous infusion into the abomasum. Periods were 14d long. Both levels of addition of lactic acid reduced (P < 0·001) the intake of silage, values being 102, 94 and 86 kg DM d^-1 for the control, LA-50 and LA-100 treatments respectively, but the casein supplement did not affect the intake of silage. Milk yield was reduced (P < 0·01) only for treatment LA-100 and, for this treatment, was restored (P < 0·01) by casein given post-ruminally. With all three silage treatments, casein infusion increased (P<0·001) the yield of protein in milk by 30–35 gd^-1. The concentration of protein in milk increased linearly (P < 0·001) with the addition of lactic acid to the silage. The addition of lactic acid produced a linear reduction (P < 0·001) in the molar proportion of acetate in rumen contents and compensatory linear increases (P < 0·001) in the molar proportions of propionate and butyrate. Changes during the day in the concentration of insulin in blood plasma followed a similar pattern to changes in the molar proportions of propionate. The mean daily concentration of insulin in plasma tended (0·10 < P > 0·05) to be higher for the LA-100 treatment, and in the immediate period after feeding this difference was significant (P < 0·05). The results confirm the effect of lactic acid in depressing the intake of silage, but they offer no support for the hypothesis that the depression of intake can be offset by an increase in the supply of protein post-ruminally.     

An evaluation of an inoculant/enzyme preparation as an additive for grass silage for dairy cattle

Herbage from the first regrowth of perennial ryegrass-based swards was directly ensiled after treatment with a bacterial inoculant/enzyme preparation (SIL-ALL, Alltech UK) at 3·0 1 t^?1, formic acid (850 g kg^?1) at 2·59 1 t^?1 or no additive (Control). The mean dry matter (DM) and water-soluble carbohydrate concentrations of the grass were 185 and 24·0 g kg^?1 (fresh basis) respectively. Lactic acid concentrations after ensiling increased at a lower rate in formic acid-treated herbage than with the other treatments. All silages were well preserved and formic acid-treated silage had a lower ultimate concentration of lactic acid and higher concentration of water-soluble carbohydrate. Effluent output was increased on a proportional basis by ?0·06 with formic treatment, whereas the inoculant reduced effluent output by 0·05 in comparison with the mean effluent production of the control silage. The in vivo digestibilities of the silages were determined using sheep. The digestibilities of DM, organic matter and energy were significantly higher with inoculant-treated silage than with formic acid treatment, whereas values for the control silage were intermediate. The three silages were offered ad libitum to forty dairy cows with individual recording of daily intakes for a 10-week period in a randomized block experiment with four treatments. Sixteen animals were offered the control silage with half of these offered 3 kg concentrates per day (C3) and the other half offered 7 kg concentrates per day (C7). Twelve animals were allocated to each of the additive-treated silages, with concentrates offered at 5 kg d^?1. Treatment effects on animal performance were measured in weeks 7–10. To compare animal performance for the treated silages with the control, an estimate of performance at 5 kg concentrates per day was obtained by regression using values obtained at 3 and 7 kg concentrates. In comparison with estimated silage intake for the control silage with 5 kg d^?1 concentrates, inoculant and formic acid treatment of the silages increased dry matter intake by 0·04 (P > 0·05) and 0·13 (P > 0·01) respectively. In comparison with estimated milk production and yield of fat plus protein for the control treatment with 5 kg d^?1 concentrates, neither inoculant treatment nor formic acid treatment produced any significant differences.     

A further study on the evaluation through lactating cattle of a bacterial inoculant as an additive for grass silage

An experiment is described in which three silages were prepared from herbage treated with either a bacterial inoculant (Ecosyl, Imperial Chemical Industries plc) at 2-71 t^?1, formic acid (850 g kg^?1, Add-F, BP Chemicals International Ltd.) at 2-21 t^?1, or no additive (control). The herbage (second regrowth from perennial ryegrass swards), was ensiled unwilted, and had mean dry matter (DM) and water-soluble carbohydrate concentrations at ensiling of 186 and 34-1 g kg^?1 respectively. The resulting silages were all well preserved and had only minor chemical differences. Thirty lactating British Friesian cows were subjected to a 21 d standardization period and were then offered the three silages for 21 d in a randomized-block design experiment. The animals were stalled individually, offered the silages ad libitum and in addition received 5 kg d^?1 of a supplement containing 198 g crude protein kg DM^?1. The mean silage DM intake, milk yields and milk fat concentrations during the final 7 d on treatment were 8-44, 8-62 and 887 kg d^?1; 238, 230 and 25-1 kg d^?1; and 368, 400 and 366 g kg^?1 for the control, formic acid- and inoculant-treated silages respectively. Following the feeding trial, six cows per treatment were subdivided to provide three animals which were offered silage alone, and three offered silage plus 5 kg d-’supplement. Rumen samples taken after 21 d on these treatments indicated no effect of the inoculant on ruman volatile fatty acid proportions, whereas the use of formic acid resulted in increases in both acetate and butyrate concentrations. The results from this study support that of the earlier work that this particular inoculant, when used at ensiling, can considerably improve animal performance over that achieved with both untreated and formic acid-treated silages.     

The effects of cereal supplementation of grass and maize silages

Grass and maize silages were fed alone and with two levels of a barley supplement to Friesian steers of about 300 kg liveweight. The organic matter (OM) intakes of grass and maize silage were similar although the OM digestibilities of the silages were 0·722 and 0·649 respectively. For both silages, barley supplementation increased total OM intake and total digestible OM intake by 0·46·0·08 and 0·37·0·06 g per g OM of supplement respectively. Liveweight gains on grass and maize silage diets were 1·38 and 1·20 kg d^-1 respectively, but the differences were not significant (P> 0·05).     

Maize silage with a non-protein nitrogen additive as feed for autumn-calving cows

Maize silages made in October were fed to forty-three autumn-calving cows during a 20-week winter feeding trial. The control silage received no additive whereas a non-protein nitrogen (NPN) additive was applied to the other silage at harvest time. The four experimental feeding treatments were: A, maize silage + 6 kg d^?1 barley; B, maize silage with NPN + 6 kg d^?1 barley; C, maize silage + 5 kg d^?1’barley + 1 kg d^?1 extracted decorticated groundnut cake; D, maize silage with NPN. The mean daily milk yields of cows on the treatments were 14.7, 15.1, 15.3 and 15.0 kg respectively. All cows received maize silage ad libitum. There were no significant differences in milk yield but the milk produced by the cows on treatment D had significantly lower concentrations of milk fat, protein and solids-not-fat when compared to the other three treatments. The cows on treatment D had a negative liveweight change which was significantly different (P < 0.05) from those of the cows on treatments B and C.     

Silage intake and milk production in cows given barley supplements of reduced ruminal degradability

Three change-over experiments were conducted to determine the effect on ad libitum silage intake and milk production in dairy cows of treatment of barley supplements with an acid-formaldehyde reagent designed to reduce the rate of starch and protein digestion in the rumen. In Experiment 1 there were six dietary treatments consisting of silage with supplements of 4·0,6·5 and 9·0 kg d^-1 of barley given untreated or treated with formaldehyde reagent (8·1 t^-1). In Experiment 2 there were four dietary treatments consisting of silage with supplements of barley (7·0 kg d^-1) or barley and fishmeal (6·0 kg d^-1 plus 1·0 kg d^-1), with the barley untreated or treated with formaldehyde reagent (15·1t^-1). In Experiment 3 there were four dietary treatments consisting of silage given alone or with supplements of barley (9·0 kg d^-1). Treated barley (15·1 t^-1, 9·0 kg d^-1) and barley plus sodium bicarbonate (9·0 kg d^-1 plus 25·0 g d^-1). Treatment of the barley supplement with formaldehyde reagent had no effect on silage intake or milk production in Experiment 1 where the rate of application of the reagent was low and the basal silage-barley diet was limiting in rumendegradable nitrogen. However, in Experiments 2 and 3 treated barley supplements were associated with improvements in silage intake and milk production. As compared with corresponding control diets containing untreated barley, increases in silage intake ranged from 0 to 0·16 of the control value, whilst associated increases in the yields of milk, milk fat, milk protein and lactose were 0·077–0·089, 0·016–0·026, 0·092–0·118 and 0·080–0·092 of the control value. These responses are discussed in relation to the increases in silage intake and milk production observed with fishmeal supplementation of the diet in Experiment 2 and inclusion of sodium bicarbonate in Experiment 3.     

A short-term comparison of the performance of four grassland-based systems of milk production for autumn-calving dairy cows

Eighty winter‐calving dairy cows of mixed parity were managed in four grassland‐based systems of milk production (F‐F, F‐C, C‐F and C‐C) over a full lactation (year 1) and during the winter period of the subsequent lactation (year 2). During the winter periods cows on systems F‐F and F‐C were offered silages of high feeding value, supplemented with 6·0 kg d^?1 of concentrate [crude protein (CP), 307 g kg^?1 dry matter (DM)] through an out‐of‐parlour feeding system, while cows on systems C‐F and C‐C were offered silages of medium feeding value, supplemented with c. 12·8 kg d^?1 of concentrate (CP, 204 g kg^?1 DM), in the form of a complete diet. After 25 February in year 1, cows on systems F‐F and C‐F were given access to grazing for periods of increasing duration, achieving full turnout on 17 April. Thereafter, until 21 October, these cows were offered a high daily allowance of herbage within a flexible grazing system (23·0 kg DM per cow, measured above a height of 4·0 cm), supplemented with 0·5 kg d^?1 of a ‘high magnesium’ concentrate. Cows on systems F‐C and C‐C (year 1) commenced grazing on 1 April, achieving full turnout on 17 April. Thereafter, until 20 October, these cows were managed on a restricted allowance of herbage in a rotational paddock grazing system, with concentrates (average allocation, 3·9 kg d^?1) being offered according to yield. In year 2, cows on systems F‐F and C‐F were given access to grazing for periods of increasing duration, from 11 March to 8 April, at which point the study was terminated. With systems F‐F, F‐C, C‐F and C‐C, mean feed inputs and milk outputs (per animal) during year 1 of the study were as follows: total concentrate DM intakes [881, 1272, 1729 and 2171 kg (s.e.m. 96·1)]; total silage DM intakes [1722, 1713, 1047 and 1154 kg (s.e.m. 70·7)], total grass DM intakes (3245, 2479, 3057 and 2481 kg) and total milk outputs [7541, 7527, 7459 and 7825 kg (s.e.m. 305·8)] respectively. Stocking rates associated with each of the four systems were 2·2, 2·5, 2·6 and 2·9 cows per hectare respectively. Performance of dairy cows on the systems during the winter of year 2 was similar to that recorded during year 1. The results of this study indicate that similar levels of milk output, DM intakes, tissue changes and plasma metabolite profiles can be achieved from grassland‐based systems involving very different combinations of grass silage, grazed grass and concentrate feeds.     

Mixing whole-crop pea–oat silage and grass–clover silage: positive effects on intake and milk production of dairy cows

Forty‐eight high‐yielding dairy cows of the Swedish Red breed were used to examine the effects of providing pea–oat silage (P), grass–clover silage (G) and a 0·50:0·50 mixture of the silages (M) ad libitum in diets with two concentrate levels (7 or 10 kg d^?1). A 9‐week experiment, including a 2‐week pre‐experimental period in which the cows were all fed the same diet, and an in vivo apparent digestibility study were conducted comparing the six dietary treatments (M7, M10, P7, P10, G7, G10). Intake and digestibility of the diets and milk production and live weight of the cows were measured. The G silage [11·3 MJ ME kg^?1 dry matter (DM)] was first‐cut grass herbage wilted for 24 h prior to addition of an additive, containing formic acid, propionic acid and ammonia, at 4 L t^?1 fresh matter (FM). The P forage was cut when the peas were at pod fill and ensiled directly with 6 L t^?1 FM of the same additive. The main hypothesis tested, that cows fed the M silage would produce more milk than the cows fed either the P or the G silages, was confirmed. The cows fed the M7 dietary treatment had similar milk yield and milk composition to cows offered the M10, G10 and P10 dietary treatments, and cows offered the G7 and P7 dietary treatments had lower milk and milk protein yields. This suggested that a mixed ration of pea–oat bi‐crop and grass–clover silage has a concentrate‐sparing effect, and that the use of pea–oat bi‐crop and grass–clover silage as a mixed ration for high‐yielding dairy cows can be recommended.     

Effect of early turnout to grass in spring on dairy cow performance

This experiment examined the effects of grazing severity and degree of silage restriction during early turnout of dairy cows to pasture in spring on animal performance. Forty late‐winter‐calving Holstein Friesian dairy cows were allocated to one of five treatments between 7 March and 17 April 1997. The treatments involved early turnout of cows to grass for 2 h per day at two residual sward heights and two silage allowances, plus a control treatment, in a randomized block design. Dairy cows on the control treatment remained indoors throughout the experiment and were offered grass silage ad libitum. Dairy cows on all treatments were also offered 6 kg d^–1 of a concentrate on a flat‐rate basis, split equally between the morning and afternoon milkings. Offering cows access to pasture in early spring for 2 h per day resulted in increases in both milk (P < 0·001) and protein yield (P < 0·01). On average, over all grazing treatments, cows produced an additional 2·6 kg milk per day compared with the control treatment (28·5 vs. 25·9 kg d^–1, s.e.m. 0·43). Furthermore, these increases in milk yield were obtained even when silage was restricted indoors (28·4 vs. 25·9 kg d^–1) and cows grazed down to a residual sward height of 40 mm (28·1 vs. 25·9 kg d^–1). Protein yield was higher (P < 0·01) with dairy cows grazing pasture compared with cows indoors (848 vs. 707 g d^–1, s.e.m. 28·9). Silage intake was significantly (P < 0·001) reduced when cows were turned out to pasture. In conclusion, early turnout of dairy cows to pasture in spring for 2 h per day reduced silage intake and increased milk yield and protein yield relative to those fully housed and offered grass silage with a low level of concentrates.     

Effects of grass pasture and concentrate-based feeding systems for spring-calving dairy cows in early spring on performance during lactation

The effect of offering a total mixed ration of silage and concentrate (proportionately 0·44 silage) system [indoor feeding system (IF)] was compared with grazing at a high daily herbage allowance with a low level of concentrate supplementation [early grazing system (EG)] in early spring on the performance of spring‐calving dairy cows in Ireland. Sixty‐four spring‐calving Holstein–Friesian dairy cows (mean calving date, 2 February) were allocated to one of two systems between 16 February and 4 April 2004. An equal number of primiparous and multiparous cows were assigned to each system. The dairy cows on the IF system were housed for a 7‐week period and offered a diet of 10·9 kg DM cow^?1 d^?1 (s.d. 2·3) of concentrate, the remainder of the diet was 8·6 kg DM cow^?1 d^?1 (s.d. 1·9) of grass silage. The dairy cows on the EG system were offered a mean daily herbage allowance of 15·1 kg DM cow^?1 d^?1 (s.d. 3·7) and were supplemented with 3·0 kg DM cow^?1 d^?1 (s.d. 1·0) of concentrate. There was no difference in milk yield between the two systems but the cows in the EG system had a higher milk protein concentration (2·9 g kg^?1) and a higher milk protein yield than in the IF system. Milk fat concentration was higher for cows in the IF than EG system (3·0 g kg^?1). There was no difference in total daily dry‐matter intake between the systems, measured in week 6 of the study. Mean live weight of the cows in the IF system was greater than in the EG system. The results of the study suggest that a slightly greater performance can be achieved by a system offering a high daily herbage allowance to spring‐calving dairy cows in early lactation compared with a system offering a total mixed ration containing a high proportion of concentrate with grass silage.     

SILAGE AND MILK PRODUCTION. A COMPARISON BETWEEN WILTED GRASS SILAGES MADE WITH AND WITHOUT FORMIC ACID

Fonr grass sUages made in May from the same herbage were compared io a 16-week feeding experiment with 12 Ayrshire cows. The silages were made from herhage wilted for either 1 or 2 days, and with or without ¹/₂ gal formic acid per ton of herhage. The silages treated with acid were, on average, 5°C cooler than the untreated silages, had lower pH values, higher lactic acid contents, slightly higher DM and crude protein contents, and higher contents of digestible organic matter in the DM. The silages were fed ad lib. with a supplement of harley and groundnut cake. The intakes of silage DM were higher with the acid-treated than with the nntreated silage. The mean daily milk yields on the silages made with and without the acid additive were 35.4 and 33.1 lb (16.1 and 15.0 kg), respectively, for the silage, wilted for 1 day and 34.2 and 32.2 lb (15.5 and 14.6 kg) for the silage wilted for 2 days. The effects of the treatments on the composition of the milk were small. It is concluded that the silages treated with formic acid additive were superior to the nntreated silages as a feed for dairy cows.     

Silage and milk production: comparisons between grass silage of three different chop lengths

Three grass silages of different chop lengths made from a uniform sward of S23 perennial ryegrass were compared in four experiments including a feeding experiment with twelve lactating cows, an eating behaviour study, a rate of passage investigation and a selection trial. The silages had median chop lengths of 9·4, 17·4 and 72·0 mm, termed short, medium and long, with pH values of 3·93, 3·94 and 4·17 and D-values of 65·9, 65·2 and 64·4 respectively. The daily intakes of silage DM and the daily milk yields increased as silage chop length decreased. The milk yield response to shorter chopping was significant with a supplement of groundnut but not significant with a supplement of sugar-beet pulp. Chop length had small and generally non-significant effects on milk composition. Eating and ruminating times expressed as min per kg DM decreased as silage chop length decreased but the retention time of the silage residues in the entire digestive tract was not significantly affected by chop length. When offered simultaneously, the intakes of the individual silages were 52·2, 31·9 and 15·9% of the total DM intake for the short, medium and long treatments respectively. Although silage with a chop length of 9 mm had nutritional advantages over longer silages, it is concluded that the mechanical and economic aspects of silage making must be considered fully when defining optimum chop length.     

The effects of degree of chopping grass for silage and method of concentrate allocation on the performance of dairy cows

Three silages were produced from the same swards by harvesting grass using either a double-chop harvester (DC) or a precision-chop harvester adjusted to produce a long staple length (PL) or a short staple length (PS). The mean particle lengths were 47, 52 and 14 mm respectively.
Of each material 250 t was ensiled unwilted and with formic acid additive at the mean rate of 2-4 litres t^-1 of grass. All three silages were well preserved and degree of chopping had no effect on fermentation as indicated by either pH, ammonia N or organic acid concentration.
The silages were offered ad libitum to seventy-two British Friesian cows with a mean calving date of 28 January which were in their second or later lactation, in a randomized-block experiment from day 8 of lactation until 12 April. In addition twelve animals on each silage received a uniform daily concentrate allowance of 7·2 kg while twelve were offered concentrates according to their individual milk yields but with a mean concentrate allowance over the twelve cows of 7·2 kg d^-1. Degree of chopping had no significant effect on either silage dry matter intake or milk yield with mean intakes during the final 21 d of the experimental period of 9·2, 9·2 and 9·2 kg d^-1 and mean milk yields of 25·2, 25·2 and 25·2 kg d^-1 for the DC, PL and PS silages respectively. Method of concentrate allocation did not affect either the total yield of milk during the experimental period, 1717 and 1697 kg, or the total lactation yield, 5635 and 5711 kg, for the uniform and yield-related allocation methods respectively. The butterfat and protein concentrations of the milk were not significantly affected by either the degree of silage chopping or the method of concentrate allocation.     

Effects of feeding clover silages on feed intake, milk production and digestion in dairy cows

Silages were made from pure crops of perennial ryegrass, red clover and white clover over 2 years. In all but one case the silage was stored as bales. A silage additive specially adapted for bales (Kofasil Ultra^TM) was used for all silages and they were all of good hygienic quality. The additive contained sodium nitrite, hexamethylene, tetraamine sodium bensoate and sodium propionate. The silages were offered ad libitum, either pure or mixed [grass/clover 0·50/0·50 on a dry‐matter (DM) basis] with a fixed amount (8 kg) of concentrate. Two experiments, one in each year, were performed with high‐yielding multiparous dairy cows in mid‐lactation, and both rumen‐cannulated and intact cows were used. The experiments were carried out using an incomplete changeover design with fifteen cows and five treatments each year. The cows consumed large quantities of these silages (12·7–16·3 kg DM per cow per day). The highest intakes were obtained when the red clover and the 0·50 red clover:0·50 perennial ryegrass silage diets were offered. However, there was a difference between years. In year 1, 0·50 red clover:0·50 perennial ryegrass and 0·50 white clover:0·50 perennial ryegrass silage diets showed the highest intakes while pure perennial ryegrass and white clover silage diets gave lower intakes. In year 2 the highest intake of silage was obtained when the diet containing silage from red clover from a second cut was offered, while the silage from red clover from a first cut gave the lowest intake. The voluntary intakes of silages from white clover and perennial ryegrass were intermediate. No cases of bloat or other digestive disturbances were observed. Milk yield was significantly lower for the perennial ryegrass silage diet compared with all other diets in year 1. In year 2 milk yield was highest for the white clover silage diets and lowest for the red clover silage diets from both cuts. In year 1 there were relatively small differences in milk composition while in year 2 milk fat content was significantly lower with white clover silage diet and milk protein content was significantly higher with the perennial ryegrass diet. The overall conclusion from these experiments was that cows were able to consume large quantities of pure legume silage without serious disturbance to their metabolism. Differences in measurements of rumen metabolism were found between diets and especially between years. Milk production differences appears to be coupled to both differences in rumen physical characteristics, such as passage rate and particle size as well as differences in volatile fatty acid production in the rumen.     

The value of malt distillers' grains ensiled with molassed sugar beet pellets as a feed for dairy cows

In one experiment twenty‐four Holstein Friesian cows, average 43 d post‐partum, were used in a changeover design experiment to evaluate the replacement of a cereal‐based concentrate supplement (C) by an ensiled mixture (MGBP) of malt distillers’ grains and molassed sugar beet pellets. The cows were offered grass silage ad libitum [dry matter (DM) content 170 g kg^?1, crude protein (CP) concentration 160 g kg DM^?1, metabolizable energy (ME) concentration 10·9 MJ kg DM^?1] and either C or MGBP at one of three levels (3, 6, 9 kg DM d^?1). The composition of C and MGBP were DM content: 853 and 296 g kg^?1, CP concentration: 202 and 187 g kg DM^?1, ME concentration: 12·6 and 10·8 MJ kg DM^?1 respectively. The cows ate all the C supplement but the intakes of MGBP were 2·7, 4·9 and 6·4 kg DM d^?1 for the 3, 6 and 9 kg DM d^?1 levels of MGBP respectively. Total DM intakes (kg d^?1) were 12·5, 15·6, 18·2 for treatments 3‐C, 6‐C and 9‐C and 13·1, 14·4 and 15·9 (s.e., 0·90) for treatments 3‐MGBP, 6‐MGBP and 9‐MGBP respectively. Milk yields (kg d^?1) for treatments 3‐C, 6‐C and 9‐C were 19·9, 23·2 and 24·2, respectively, and for treatments 3‐MGBP, 6‐MGBP and 9‐MGBP were, 20·3, 21·3 and 23·0 respectively (s.e., 1·05). Milk fat contents (g kg^?1) for treatments 3‐C, 6‐C and 9‐C were 42·8, 42·3, 43·5 respectively and for treatments 3‐MGBP, 6‐MGBP and 9‐MGBP were 39·5, 38·7 and 38·2 (s.e, 1·86), respectively, and milk protein contents (g kg^?1) for treatments 3‐C, 6‐C and 9‐C were 30·5, 30·6, 31·8, respectively, and for 3‐MGBP, 6‐MGBP and 9‐MGBP were 30·0, 30·8 and 31·2 (s.e., 0·66) respectively. Milk yield and milk protein contents were significantly higher for the higher levels of supplementary feeding but there was no difference between the types of supplement. The milk fat contents were significantly lower on the MGBP than C supplements. In a second experiment fifteen Holstein Friesian cows, average 126 d post‐partum, were used in a changeover experiment to evaluate the replacement of all (treatment M) or half (treatment MS) of the grass silage (S) in their diet by a mixture of MGBP and straw. All cows received 5·1 kg DM d^?1 of concentrate feed. Forage DM intakes were 8·3, 11·2 and 14·2 kg DM d^?1 for the S, MS and M treatments respectively. Milk yields (kg d^?1) for S, MS and M treatments were 17·0, 19·4 and 20·0 (s.e., 0·56) respectively. Corresponding contents of milk fat and protein (g kg^?1) were 42·0, 41·4, 38·6 (s.e., 0·37) and 33·8, 34·1, 34·2 (s.e., 0·42). Ensiled mixtures of malt distillers’ grains and molassed sugar beet pellets can be used to replace some of the conventional concentrates or grass silage for dairy cows giving moderate yields without a loss of production.     

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

A 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.