摘要:

AbstractA total of 1713 samples of silage from commercial farm silos were analysed to investigate the effect of dry matter (DM) content and chemical additives on fermentation as measured by ammonia‐N concentration and pH, Increasing DM content without additive use had a major beneficial influence upon fermentation. When silage DM contents were greater than 260 g kg‐183% of silages were well fermented, with average ammonia‐N concentrations of 94 g (kg total N)‐1and pH 4.36. With diminishing DM concentration the proportion of well fermented silages declined. In the DM range 220‐260 g kg‐167% of silages were well fermented with ammonia‐N concentrations of 125 g (kg total N)‐1and pH 4.30, in the DM range 180‐220 g kg‐148% were well fermented with ammonia‐N at 151 g (kg total N)‐1and pH 4.38 and with DM below 180 g kg‐1no silages were well fermented with ammonia‐N concentration of 252 g (kg total N)‐1and pH 4.84.The benefit of chemical additives, albeit at poorly defined and often inadequate rates, was small in comparison to that of increased DM concentration. Below DM concentrations of 180 and 220 g kg‐1, the only benefit was that formic acid decreased ammonia‐N to 151 g (kg total N)‐1and pH to 4.32 compared with 163 g (kg total N)‐1and pH 4.43 for untreated silages. Within the DM range 220‐260 g kg‐1formic acid decreased ammonia‐N level to 104 g (kg total N)‐1and pH to 4.07, and there was a slight benefit from using sulphuric acid/formalin which decreased ammonia‐N to 117 g (kg total N)‐1and pH to 4.23 compared with 125 g (kg total N)‐1and pH 4.27 for untreated silages. Above 260 g DM kg‐1both formic acid and sulphuric acid/formalin provided a small but consistent decrease in ammonia‐N and pH compared with untreated silages. Chemical additive use conferred no other benefit when compared with untreated silage. Calcium formate/sodium nitrite mixtures and acid mixture use provided no

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02084.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe 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 23factorial 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‐1protected soya bean). No concentrates were offered pre‐calving and all animals were given 7.6 kg d‐1concentrates 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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02085.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA large‐scale sealed system for freeze‐drying herbage is described. It utilizes the principle of sorption drying and is dependent upon the vapour pressure differential (VPD) between the herbage and the silica gel drying agent. Ice sublimes to vapour from the sample in a system operating at approximately – 10°C and the vapour is adsorbed by silica gel in an air stream recycled by a blower; equal masses (up to 50 kg each) of wet herbage and silica gel are used. The system is simple to construct and is relatively inexpensive.Approximately eight days drying time are needed to reduce moisture content from 90 to 10%. Twenty‐four different species or cultivars of both temperate and tropical grasses and legumes sampled at several stages of maturity have been dried in the system. When snap‐frozen herbage is freeze‐dried by this process the physical and chemical changes that otherwise occur when herbage is harvested and prepared for evaluation can be reduced and sufficient material can be obtained to permit animal feeding studies as well as chemi

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02086.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractTemperature and daylength treatments have been used to investigate the apparent link between the potential for rapid leaf extension in spring and floral initiation and development in Lolium perenne (cv. Vigor). After growth at 5°C for 10 weeks (vernalization treatment) the leaves which developed at 15°C expanded significantly faster than non‐vernalized controls under both long and short days. Under long days floral development was initiated in vernalized plants but under short days it was not. Specific leaf area was higher in vernalized than non‐vernalized plants under long days.The photosynthetic capacity of leaves which developed on plants which had been previously vernalized and then grown at 15°C under long days was higher than non‐vernalized controls when expressed on a leaf area and dry weight basis, but not on the basis of chlorophyll content. Vernalization followed by short days resulted in a smaller and non‐significant increase in the photosynthetic capacity of leaves.Application of gibberellic acid (GA) as a spray to non‐vernalized plants did not affect floral development but did increase the rate of leaf extension. The application of GA did not affect specific leaf area or photosynthetic capacity expressed on a

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02087.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractFour management systems involving different dates for first harvest (simulated grazing, early silage, late silage and hay) and two fertilizer N rates in spring (0 and 80 kg ha‐1) were imposed on a perennial ryegrass cv. Talbot/white clover cv. Blanca sward during 1981‐82. In each year, annual total herbage DM was increased by spring application of N but white clover production and content in the total herbage were reduced; however, white clover, which was depressed in the harvests immediately after N application, recovered during the season to amounts and contents in the total herbage similar to those given no spring N.Annual total herbage DM production increased as the date of primary harvest was delayed (935 to 1197 t ha‐1over two years) but mean organic matter digestibility values for the same period decreased (0‐769 to 0700). First‐harvest production made up substantial proportions of the annual production in the conservation systems. White clover, as shown by its production and the amount of stolon present, was tolerant of conservation systems, especially with no applied N.It is concluded that grass/white clover swards are suitable for management systems which involve cutting for conservation. The use of strategic spring N seems a viable option, but more knowledge of rates would be valuable since this experiment only compared 80 kg ha‐1with n

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02088.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThis work examined whether or not Holcus lanatus, cv. Massey Basyn, is an improvement on plants from German Commercial seed of this species and whether either could outyield Lolium perenne cv. Aberystwyth S23. The three grasses were sown in monoculture in a field near Oxford and received a total of either 250 or 500 kg N ha‐1over two years. They were also sown with Tri‐folium repens cv. Blanca. The plots were cut 11 times over the 2‐year period at a height of 50 mm from ground level.At the high rate of nitrogen Lolium perenne always gave the highest yields of DM and DOM. In the second year, both types of H. lanatus gave higher yields than L. perenne at the low level of N. The L. perenne and T. repens mixture yielded more than that with H. lanatus and T. repens. H. lanatus depressed the yield of T. repens more than did L. perenne. H. lanatus h lanatus; Massey Basyn was affected less by rust infection than was German Commercial H. lanatus. At the final harvest, plots with r. repens contained more unsown grass than did N‐fertilized plots sown to grass

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02089.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThirty‐six British Friesian heifers were divided into two groups during weeks 3‐26 of lactation and received ad libitum either good (G) or average (A) quality grass silage. The in vitro digestible organic matter in the DM was 680 and 600 g kg‐1for silages G and A, respectively. In addition, the heifers in each group were offered concentrate at either a low (4.3 kg DM d‐1), medium (64 kg DM d‐1) or high (8.4 kg DM d‐1) level. The concentrate contained 180 g (kg DM)‐1of crude protein and had a calculated metabolizable energy concentration of 12.9 MJ (kg DM)‐1.Increasing concentrate level significantly increased milk yield (P<0.01), milk protein concentration (P<0.05), and yield of both milk protein depressed milk fat concentration (P<0.001) and silage intake (P<0.001).Although the overall effect of silage quality on milk yield was not significant, the milk yields for silage G at each concentrate level were higher, significantly so for low level, than the corresponding values for silage A. An improvement in silage quality did not affect milk fat concentration but significantly increased the concentration of milk protein (P<005) and yields of both milk fat (P<005) and protein (P<0001). The response of silage DM intake to improved silage quality was 0 06 kg DM per 10 g rise in vitro DOMD value. Each additional kg concentrate DM depressed intake of silages G and A by 0‐63 and 0‐27 kg DM, respectively. Substitution rate was also significantly related to stage of lactation.With both silages, the digestibility coefficients determined in vivo for acid detergent fibre (ADF) decreased significantly (P<0.001) when concentrate level was increased from low to high. Differences for DM, OM and total N digestibility coefficients between treatments were not established as significant at the 5% level.Estimates of mean efficiency of utilization of ME for lactation, made on a weekly basis, were 049 and 052 for the heifers given silages G and A. respectively, and 048, 052 and 052 for those given the low, medium and high levels of concentrate. Energy balances were calculated on

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02090.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractTwo experiments were carried out to examine the effects of grazing severity on the performance of January/February calved British Friesian dairy cows. In Experiment 1, three groups of cows were rotationally grazed across twenty‐four one‐day paddocks with high (H), medium (M) or low (L) herbage allowances. Cows on treatment M were offered a daily herbage allowance designed to achieve a residual sward height of 50 mm, assessed by a rising‐plate sward stick. The daily herbage allowance (g organic matter (kg live‐weight)‐1on treatments L and H were 0.30 below and above that for M, respectively, to give residual sward heights of 42 and 59 mm. In Experiment 2, three groups of cows were grazed across twenty‐four one‐day paddocks to obtain residual sward heights of 50 mm (severe), 60 mm (moderate) and 80 mm (lax).Average milk yields on the L, M and H treatments in Experiment 1 were 11.8, 14.6 and 14.5 kg d,‐1and in Experiment 2 they were 13.7, 16.0 and 17.0 kg d‐1on the severe, moderate and lax treatments, respectively. The results indicate that the critical herbage height below which milk production per cow declines may vary with the production potential of the animal. There were no significant treatment effects on milk composition.Milk output ha‐1and utilized metabolizable energy ha‐1were greatest with the low herbage allowance in Experiment I and the moderate treatment in Experiment 2. Net herbage accumulation on the severe treatment in Experiment 2 was 30% lower than that on the lax treatment, as a result of treading damage in early season.It is concluded that, in a rotational grazing system, a reasonable compromise between sward utilization and animal performance can be achieved by grazing January/February calved cows to a residual sward height of 60 mm as assessed by a rising‐plate sward stick. This is equivalent to a sward surfac

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02091.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractSpectral reflectance measurements were found useful in estimating the dry green biomass (DGB) in hayfields in eastern Québec, Canada. The calibrated measurements of reflectance obtained in the 650 and 800 nm bands (respectively defined as the RED and NIR indices), the NIR/RED ratio, and the ratio (NIR‐RED)/(NIR + RED) were used to generate various regression models which explained between 74 and 90% of the variance in DGB. The proportion of legumes, grasses and herbs in the canopy had no apparent influence on the reflectance measurements or on the value of the mode

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02092.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA series of comparisons was made of the bite rates of fistulated and non‐fistulated cattle and sheep, grazing four grassy hill plant communities over four years. Both bite rates and grazing times were recorded on two occasions. Comparative observations were also made on faecal cuticle concentrations on one grassy and one dwarf shrub community and on faecal ash, nitrogen (N) and acid detergent fibre (ADF) concentrations throughout one year.Faecal N concentrations were slightly but consistently higher in fistulates than in non‐fistulates, but faecal ADF and ash concentrations and the relative proportions of faecal cuticle fragments were similar and did not indicate differences in either diet composition or digestive efficiency. Bite rates did not differ significantly between fistulates and non‐fistulates, except on the two occasions when fistulates carried Vibracorders to measure grazing time without preliminary training, and grazing times did not differ significantly. There were significant differences between cattle and sheep in most variables.On the basis of this evidence, there is no reason to expect that fistulated and non‐fistulated animals of similar history and nutritional background will differ in grazing behaviour or diet comp

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02093.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY