The herbage intake of June/July calving cows in early lactation is limited by a number of factors including the quality of the sward. A typical management strategy is to graze dry cows at a high stocking rate at turnout to maximise the silage area and graze the freshly calved cows on silage aftermaths. A further refinement could be the use of clover rich swards. Winter feeding experiments have demonstrated that animals can eat more and perform better when offered a clover rich silage rather than a conventional silage. The following experiment was carried out to establish whether similar benefits would result from the grazing or clover rich swards.

In a continuous design experiment lasting 12 weeks, sixteen summer calving British Friesian cows (mean calving date 7 June) were allocated to either a perennial ryegrass dominant sward (PRG) or a white clover rich sward (WC) silage aftermath. The target sward height was 7-10 cm measured by swardstick. Additional cows were available on a put and take basis to maintain parity between the sward heights in the two treatments.

There is increasing interest in the use of white clover rich swards in dairy cattle systems in response to evironmental pressures and the introduction of milk quotas. White clover (Trifolium repens) in association with Rhizobium bacteria in a mixed sward receiving no fertilizer nitrogen can produce yields equivalent to a grass sward receiving approximately 200 kg N/ha/annum. Field scale cutting experiments (Roberts et al, 1989) have deomstrated that under an intensive 3-cut silage regime a grass/white clover sward receiving no nitrogenous fertilizer can yield 0.71 of the DM herbage output of a grass sward receiving between 320 and 340 kg N/ha/annum. Feeding experiments have demonstrated the ability of white clover to improve milk yield and composition (Castle et al, 1983, Thomson, 1984). To further investigate the potential of white clover for dairy cattle a systems study is being conducted. This paper summarises the performance of the two herds in the first year.

When concentrate allowance is changed the allowances of both energy and crude protein change. In this experiment, which was part of a larger series, concentrate energy supply was increased at a constant supply of crude protein.

Sixteen Ayrshire and Friesian cows were given either 4kg/d of a high protein concentrate (321g/kg DM), T4, or 8kg/d of a low protein concentrate (173g/kg DM), T8, as well as ad. libitum access to silage through Calan-Broadbent gates (pH 3.8, DM 220g/kg, ME 10.1 MJ/kg DM, CP 147g/kg DM, NH3-N 43g/kg total N). There were two periods of 8 weeks starting three weeks after calving. Performance in week two was used as a covariate. The treatments in the two periods were: T4/T4, T4/T8, T8/T4 and T8/T8. Milk yields and silage intakes were recorded daily; milk composition was measured weekly and cows were weighed twice weekly by weighband.

Over recent years extremes of weather at traditional silage making time have made the manufacture of high quality forage difficult. Consequently a trial was run at the BOCM SILCOCK Development Unit, Barhill, evaluating a compound diet as a complete silage replacement. The analysis of the silage replacer nut (SRN) was 35g oil (OAH)/kg DM, 115g crude protein (CP)/kg DM, 279g crude fibre (CF)/kg DM and an ME of 9 MJ/kg DM. The diet contained 50% VITON-NIS (sodium hydroxide treated straw).

There are well established differences in the digestion characteristics of the carbohydrate sources available for inclusion in rations for dairy cows, but the implications of these differences for milk production remain poorly defined. The experiment reported here was conducted to compare 4 concentrates containing contrasting carbohydrate types, namely sources of readily-fermentable starch (barley), of sugar, of starch that is fermented relatively slowly in the rumen such that some is absorbed as glucose from the small intestine (maize) and of sugar and digestible fibre (citrus pulp). Given the advantages of dietary inclusion of appropriate fats as a means of increasing the energy density of the ration and/or of producing ‘less-saturated’ milk fat, and the likelihood that responses to high-fat diets would be modified by carbohydrate type, the different carbohydrate sources were compared in concentrates containing a high proportion of fat (16% on a fresh weight basis) as calcium salts of long-chain fatty acids.

In order to examine the locomotion characteristics of dairy cows in Wales and South West England, nine herds with a range of calving patterns, where locomotion scored using a scale from one (good) to five (recumbent) including half scores. Each herd was examined three times; at the end of the 1988 grazing season, late in the following winter housing period and finally towards the end of the 1989 grazing season. A total of 1,166 cows were seen on at least one occasion. The change in score arising from housing and the subsequent return to grazing was examined for the 464 cows which had been seen on every occasion.

Yields of milk and its constituents recorded by National Milk Records (NMR) are used to estimate total lactation yields and to predict future yields while the lactation is still in progress. Morant and Gnanasakthy (1989) developed new lactation curves of the form:

where t is the days since calving and t' = (t-150 ) /100, for cows on a complete diet throughout lactation. The objective of this study was to extend this model for use with cows at grass during the summer months.

Approximately 2000 2nd and 3rd lactations of Friesian/Holstein cows, 1013 from the North and 960 from the South West of England, were obtained from the NMR data base by systematic sampling. The sampling fraction was 0.1. The cows calved between October 1987 and September 1988. Their lactations spanned at least 305 days and were recorded at approximated monthly intervals. In each of two regions the average milk yield in each month of lactation for cows calving in each month of the year were calculated. To obtain Initial estimates of grazing effects on the shape of the lactation curves, twelve dummy variables (gi, i=1, 2…12), where gi=1 for ith calendar month of recording and 0 otherwise, were included in the model.

The use of whole-crop wheat harvested at the hard dough (55-65% DM) stage has advantages of high yields of DM, and no effluent production. Treatment with urea prior to storage prevents fermentation or moulding, increases the nitrogen (N) content and may increase digestibility (Deschard et al, 1987; MacDearmid et al, 1988).

The objective of this experiment was to investigate the intake and digestibility of urea-treated whole-crop wheat when fed alone, or when supplemented with an energy supplement (molassed sugar beet pulp) and a protein supplement (fish meal).

Grass forms a major component of the total ruminant feed in both Ireland and the UK. Much of the grassland consists of permanent swards of diverse botanical composition with many of the grass species present considered ‘secondary’ or ‘undesirable’ (Frame and Tiley, 1987). The objective of this study was to compare reseeded Lolium multiflorum and Lolium perenne swards with an old permanent grassland sward managed under intensive silage conservation systems, and to determine the annual production of grass silage and subsequent beef carcass output per hectare when the silages were offered to finishing cattle.

Acetate conversion to fatty acids in adipose tissue requires NADPH which, in ruminants, is generated mainly by the oxidation of glucose via the pentose phosphate pathway and from acetate via the isocitrate cycle. In ruminants negligible amounts of glucose are absorbed from the alimentary tract and glucose is synthesized from propionic acid and gluconeogenic amino acids in the liver. Silage diets are high in lipogenic precursors (acetate and butyrate) but characterized by low amounts of gluconeogenic precursors. This should give high levels of fat deposition, but the limited supply of glucose or its precursors may still result in an excess of acetate production relative to its utilization. Fishmeal (FM) supplementation of silage diets tends to stimulate silage intake and liveweight gain probably due to an increased protein supply and improved energy/protein imbalances in the rumen, but its effect on lipid metabolism has not been fully elucidated.

ADAS costings show that the dairy farmers with the highest margins per litre of milk sold are those who maximise yield from home grown forages. Forage quality obviously has an influence on cow performance but high intakes are the most important factor in determining yields.

Many physical and chemical factors can affect the nutritional value of silage and consequently intake.

The major deficiency of well fermented silage is that levels of residual sugars are normally very low (<10g/kg DM), this reduces the potential microbiological activity in the rumen. In addition the products of the silage fermentation affect palatability and can limit intake.

Restriction of the silage fermentation to a minimum, should overcome the nutritional limitations caused by the fermentation process, increasing intakes and the resulting animal performance.

When grass with an adequate content of fermentable substrate and epiphytic lactic acid bacteria is ensiled properly, the fermentation which follows is normally considered satisfactory. This fermentation can be altered by various categories of additive such as acids, sugars and inoculants, each of which can influence the fermentation differently. The experiment reported compared the fermentation products, aerobic stability and animal performance for silages made using formic acid or a Lactobacillus plantarum inoculant with well preserved silage made without additive treatment.

A 42 day regrowth of Lolium multiflorum (cv. Lemtal) was harvested without wilting using two precision - chop harvesters. Alternate loads of grass were ensiled with (a) no additive, (b) formic acid (850g/kg) at 3.0 1/t or (c)inoculant (Ecosyl - ICI plc) at 3 1/t (separate harvester). The inoculant was constituted immediately before use and was applied in accordance with the manufacturers instructions. Harvesting was completed and the silos sealed within 26 hours of mowing. The silos were opened after 113 days.

The conservation of herbage as silages results in a reduction in the nutritive value of the crop as a result of extensive proteolysis. Measurement of the major end products of proteolysis such as ammonia and amino acids has been studied extensively e.g. Oshima el al. (1979). Considerably less attention has been given to the fate of plant proteins during ensilage (Fairbairn et al., 1988). Since this may lead to a better understanding of the mechanisms involved in proteolysis and thus to improvement in its control the present study was designed to follow changes in the major nitrogenous constituents, particularly proteins and peptides, through time course sampling of silages made from perennial ryegrass with and without additives.

Perennial ryegrass (23% dry matter) was ensiled in laboratory silos (1 kg fresh matter), either untreated (UT) or treated with formic acid (FA) (ADD-F, BP Chemicals, UK: 3.3 l/tonne) or a cellulase enzyme preparation (E) (FSO-1), Forum Feeds, Finland; 0.22 1/tonne).

The biological silage additive, Safe-Sile, is a commercial product prepared by Microferm Ltd. and the objective of the experiment was to appraise its efficacy in the conservation of silage and its subsequent feeding value.

Safe-sile contains lactic acid bacteria (2.5 x 109 cfu/g consisting of proportionately 0.75 Lactobacillus plantarum and 0.25 Pediococcus acidilactici) together with enzymes (hemicellulase, amyloglucosidase and cellulase) and a mixture of bacteriophages (2.5 x 109 pfu/g). These active ingredients are carried in dextrose together with mineral salts, trace elements and vitamins.

Two silages were made in September 1988 from third-cut wilted grass, one silage receiving no additive (control treatment) and the other receiving Safe-Sile at the rate of 1 kg per 15 tonnes of grass approximately. The fields harvested for this experiment were perennial ryegrass/white clover swards and the silages were made after a field wilting period of 24 hours under good silage-making conditions.

It Is claimed that the use of the correct enzyme system as an additive on grass silage will satisfactorily control the fermentation and reduce the cell-wall fibre content, thus preserving the nutrients In the silage and aiding their utilisation by the animal (Henderson and McDonald, 1977; Huhtanen et al, 1985; Raurama et al, 1987; Chamberlain and Robertson, 1989; Gordon, 1989;).

The aim of the present experiment was to assess the effect of biological additives, enzymes or a combination of enzymes with an Inoculum of lactic acid bacteria, on the composition of silage and on its nutritive value when offered to store lambs as the sole constituent of their diet.

On 1st June 1988, first cut perennial ryegrass (Lolium perenne L) at pre-ear emergence was ensiled direct cut untreated (U), treated with a commercial enzyme (E) or with a commercial inoculum of lactic acid bacteria with enzymes (I) in 6t capacity bunker silos. The grass was cut with a mower and lifted with a New Holland precision chop forage harvester. The additives were pumped onto the grass using a dribble bar sited over the pick-up drum.

The N fraction of fresh grasses, silages and hays is generally considered to be extensively degraded in the rumen. However published N degradability values for each type of material vary over quite a wide range. This may, at least in part, be due to an effect of the stage of growth of the harvested material since with increasing maturity there are marked changes in chemical composition and botanical features. Accordingly the ruminal N degradability characteristics of perennial ryegrass, harvested at different stages of growth and conserved as hay or silage, were determined using the polyester bag procedure.

Crops of young primary growth (C1), first regrowth (C2) second regrowth (C3) and mature primary growth (C4) were harvested from a field of perennial ryegrass c.v.S23. For each crop the fresh grass was stored frozen, conserved as field-cured hay and conserved by ensiling in laboratory silos either directly or after wilting and in both cases with or without formic acid addition (3l/tonne). The silos were opened after 90d and the silages subsequendy stored frozen.

Concentrate feed with high-glucosinolate rapeseed meal (BRSM) as the sole protein supplement was eaten less readily by weaned calves than a similar feed based on soyabean meal (Stedman et al, 1983), and this was so whether intake was measured during continuous ad libitum feeding, or for short periods, 0.5 h, after twice-daily feeding with changes of feed each day. In these and other experiments with calves (Stedman and Hill, 1987), concentrate feeds based on low-glucosinolate rapeseed meal were eaten more readily than those based on high-glucosinolate meal, but intake of the low-glucosinolate feeds rarely matched that of the corresponding feed containing soyabean meal.

Lambs given ad, libitum, a compound concentrate feed containing a high proportion of a high glucosinolate rapeseed meal gained weight at a significantly lower rate than similar lambs given a concentrate feed based on soyabean meal (Stedman et al, 1983). The glucosinolate content of the concentrate feed containing rapeseed meal was just over 20 µmol/g. In the experiment described here the effects on lamb weight gain and concentrate intake were determined from a range of compound feeds containing the same proportion of rapeseed meal but different glucosinolate contents, to a maximum approaching 20 µmol/g.

Two rapeseed meals were used, one of low glucosinolate content (Dolar-DRSM), about 3.5 µmol/g, and the other of high glucosinolate content (autumn UK sown variety - BRSM), about 85 µmol/g. Eight compound concentrate feeds were prepared (Table 1), all containing 0.20 rapeseed meal but having calculated glucosinolate contents of 0 to 17.5 µmol/g. Their ME value was 12.5 MJ and CP 200 g/kg DM. The mineral and vitamin supplement provided 0,8 mg I/kg concentrate feed.

The use of full-fat rapeseed in non-ruminant animal feeding has for long been limited by the presence of anti-nutritive components. However, triple-low varieties have a considerable potential as a source of both protein and dietary energy in diets, although there is the need for precise information on the relative nutritive value of full-fat rapeseed and the resulting extracted oils and meals before they may be effectively and economically incorporated into animal diets.

The rapeseed products evaluated comprised ground full-fat rapeseed (FFRS) extracted rapeseed meal (RSM) and rapeseed oil (RSO) all from a triple-low variety, Brassica campestris SVO 333, obtained from Dalgety-Panmure Co. Angus, U.K. The RSO, RSO plus RSM (ORSM) and FFRS were included to give levels of added oil of 40, 80 and 120 g/kg at the expense of the energy-yielding ingredients of the basal diet (Table 1). The RSM was incorporated into the basal at the same rates as in ORSM. All experimental diets were fed to 13 Landrace x (Landrace x Large White) gilts of 46kg average initial live weight in a metabolism trial conducted over four successive time periods. A ten-day acclimatisation in holding pens preceded a 5-day total collection of faeces (using indigo carmine as marker) and urine (facilitated by indwelling bladder catheter) in metabolism crates. The rapeseed products, diets, oven-dried faeces and freeze-dried urine were analysed for gross energy (GE) and (except urine) for oil content. Apparent digestible energy (DE) of test materials were derived by regression analysis. DE of oil was also derived indirectly as a product of oil digestibility and oil GE.

Since whole rapeseed is a high energy feed source but only moderate in protein content and value it is desirable to combine it with another feedstuff such as peas so that the combined product has an improved balance of amino acids and a more favourable protein to energy ratio. Extrusion is a useful method of processing a rape:pea mixture since this results in effective release of oil from the rape and its absorption by the pea. The heat generated by extrusion could also lead to the destruction of heat labile anti-nutritive factors in both rapeseed and peas.