ALBERT

Notes: 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.

Notes: 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.

Notes: 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.

Notes: An investigation into the effect of including dried grass in the supplement given to dairy cows at pasture is reported. Supplements containing 0, 50 and 100% dried grass were used in the investigation which was carried out in two parts. In the first part 12 high-yielding cows with unrestricted access to pasture were used in an experiment with a change over design to assess the effects of feeding 5 kg/day of each supplement on milk yield and composition. In the second part 8 steers, housed in stalls and given cut herbage from the same sward as that grazed hy the cows, were used in a change over experiment to assess the effects of the three supplements on herhage and total DM intake. No significant differences in milk yield between supplements were ohtained, the mean yields being 23·9, 24·5 and 23·9 kg/day for the supplements containing 0, 50 and 100% dried grass, respectively. Milk composition was also not significantly affected by including dried grass in the supplement. In the indoor feeding trial using the steers, the addition of 3·5 kg DM from the supplement resulted in an increase in total DM intake of only 1·3 kg/day. There was no significant difference hetween supplements on herbage and total DM intake.

Notes: Abstract Two experiments were carried out in consecutive years to examine the influence of cutting date and restricting fermentation by carboxylic acid treatment on the nutrient intake from grass silage by beef cattle. In year 1, four cutting dates during July and August after a primary growth harvest and, in year 2, five cutting dates of primary growth between mid-May and early July were examined. Herbage was ensiled either untreated or treated with high levels of acid additive (‘Maxgrass’, mean 8·6 l t−1). Ninety-six (year 1) or forty-eight (year 2) continental cross steers were used in partially balanced changeover design experiments with each silage type either unsupplemented or supplemented with 4·5 (year 1) or 5·5 (year 2) kg concentrates head−1 d−1. Silage digestibility declined significantly between initial and final harvest dates (P 〈 0·001), whereas silage dry-matter (DM) and digestible energy (DE) intakes were significantly higher in the initial compared with final harvest dates in both years of the study (P 〈 0·01). Similarly, silage DM and DE intakes, and total DM intakes, of acid-treated and unsupplemented silages were greater than those of untreated and concentrate supplemented silages, respectively (P 〈 0·001). The results indicate that earlier cutting dates, and addition of acid to herbage before ensiling, can increase silage DM intake by beef cattle.

Notes: The effects of offering a range of grass silages and mixtures of grass and maize silages on the intake of beef cattle were studied. Four grass silages (GS1, GS2, GS3 and GS4) were used. Grass silage 1 was ensiled from a second regrowth in mid-late September and treated with an inoculant additive. Grass silages 2, 3 and 4 were ensiled, without additive, from a primary regrowth harvested in early July, late May and mid-June respectively. Wilting periods were 8, 30, 36 and 36 h for GS1, GS2, GS3 and GS4 respectively. Grass silages 1, 2 and 3 were precision chopped and ensiled in bunker silos, while GS4 was ensiled in round bales. The DM content (g kg−1) and starch concentration (g kg−1 DM) of the three maize silages (MS1, MS2 and MS3) used were 256 and 128, 256 and 184, and 402 and 328 for MS1, MS2 and MS3 respectively. Seventy-two Charolais and Limousin cross-bred steers were used in a changeover design with two 4-week periods. The study consisted of sixteen treatments incorporating the four grass silages fed alone and with the three maize silages arranged as a 4 × 4 factorial design. The grass silage and maize silage mixtures were offered in a ratio of 0·60:0·40 (DM basis) once daily using individual Calan gates. All silages were offered ad libitum with 3 kg per head per day of a concentrate supplement. Dry matter and metabolizable energy (ME) intakes were highest with diets based on grass silage GS4 compared with diets containing the other grass silages. Metabolizable energy intakes of diets containing no maize silage, and those based on MS1 and MS2, were similar (P 〉 0·05) but lower than that of diets containing MS3. Only limited increases were found in DM and ME intakes with the inclusion of maize silage in grass silage-based diets while offering high-quality grass silage (assessed in terms of DM content, and fibre and N concentrations) promoted high voluntary intakes.

Notes: Forty British Friesian cows with a mean calving date of 28 January were used in a randomized block design experiment to evaluate a high-quality grass silage for milk production. The high-quality silage was made from two consecutive cuts of a perennial ryegrass sward after regrowth intervals of 37 days, wilted to 51% dry matter, finely chopped and ensiled using 2.2 1 t-1 (0.5 gallons per ton) of formic acid. The resulting silage had a dry matter digestibility of 72.9% and was fed ad libitum with 3.8 kg (8.4 lb) concentrates as a supplement. A medium-quality grass silage, of lower digestibility and dry matter content (70.0 and 25.4% respectively), was also fed ad libitum in addition to either 3.8, 5.7 or 7.6 kg (8.4, 12.5 or 16.7 lb) concentrates. The feeding treatments were commenced immediately after calving and were terminated on 9 April giving a mean period of 72 d on the treatments. Over the experimental period the animals on the high-quality silage consumed 15% more silage dry matter and produced 8% more milk that those on the medium-quality silage with the same level of concentrate supplementation. From the results it was estimated that 1.9 kg (4.3 lb) of additional concentrates would be required with the medium-quality silage to give an equivalent milk output to that achieved with the high-quality silage. Milk composition, liveweight change, ration digestibility and nitrogen balance data are also presented.

Notes: An experiment designed to compare the nutritive values for milk production of dried grasses harvested in spring and autumn is described. The DM digestibility of the spring- and autumn-dried grass was 67±7 and 66±0%, respectively. Both dried grasses were fed at two levels, 0±4 and 0±5 kg/ kg milk (4 and 5 Ib/10 Ib milk), to lactating cows in a randomized-block design experiment using 24 animals. Each animal was also given 2±5 kg hay/day (5±5 Ib) and in addition sufficient of the dried grass under investigation to meet maintenance requirements.Milk yield, milk energy output, live-weight gain and the solids not fat (SNF) and protein contents of the milk increased with feeding level. Season of dried grass harvesting had no effect on milk yield, milk energy output or live-weight change. The spring-harvested dried grass resulted in a significantly higher milk SNF content than the autumn-dried grass and also tended to reduce milk butterfat level.

Notes: 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.

Notes: Abstract The effects of level of concentrate supplementation on the response of dairy cows to grass silage-based diets containing a constant proportion of fodder beet were examined. Forty Holstein-Friesian dairy cows of mixed parity were used in a 2 × 5 factorial design experiment. Two basal diet types [grass silage alone or grass silage mixed with fodder beet in a 70:30 dry matter (DM) ratio] were offered ad libitum, and the effects of five levels of concentrate supplementation (mean = 3·0, 5·3, 7·5, 9·8 and 12·0 kg DM per cow d−1) were examined. Concentrate supplements were offered via an out-of-parlour feeding system. These treatments were examined in a three-period (period length = 4 weeks) partially balanced changeover design experiment.Fodder beet inclusion had no significant effect on the estimated metabolizable energy (ME) concentration of the ration (P 〉 0·001). Total DM intake, estimated ME intake, milk yield, milk protein content and milk energy output all showed significant linear increases with increasing level of concentrate inclusion (P 〈 0·001) while, in addition, milk yield and milk energy output exhibited a significant quadratic increase (P 〈 0·01). The inclusion of fodder beet in the diet reduced silage DM intake (P 〈 0·01) but resulted in an increase in total DM intake and estimated ME intake (P 〈 0·001). However, inclusion of fodder beet had no significant effect on milk yield (P 〉 0·05), while increasing milk protein content and milk energy output (P ≤ 0·05). Milk energy output, as a proportion of estimated ME intake, was significantly (P 〈 0·001) reduced by fodder beet inclusion (0·44 vs. 0·38).Despite large increases in estimated ME intake with the inclusion of fodder beet at all levels of concentrate supplementation, milk energy output responses were small, resulting in an overall reduction in the efficiency of conversion of ME intake into milk energy output. An increased partitioning of dietary ME intake to tissue gain is suggested as the most likely explanation for the observations made.