摘要:

ABSTRACTPalatability studies of 29 species of grasses, legumes and herbs, and two seeds mixtures, were conducted using three replicates of each species. Crossbred ponies and a few Thoroughbreds were obserred and timed for a total of 260 hours grazing. The results were analysed and sbowed small statistical differences between replicates, between tbe 2 years observed and between horses; and highly significant differences (P<0.001) between certain species. The most palatable was a clover‐rich mixture. Tbe pasture varieties of perennial ryegrass were significantly more palatable tban S24, and as palatable as timothy and cocksfoot Alta tall fescue, crested dogs tail and wild white clover were palatable. Some herbs, red clover, brown top, red fescue and meadow foxtail were tbe least palatable. Dandelion, ribgrass and yarrow were palatable herb

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00732.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTNo one method of drying can be relied upon for all plant species, plant parts, or form (e.g., fresh v. ensiled herbage). Least changes in nonstructural carbohydrates appear to occur when fresh tissue is immersed in boiling alcohol. Freeze‐drying provides results more similar to fresh tissue than heat‐drying. Heat‐drying at high temperatures (above 80°C) can cause thermo‐cbemical degradation, while slow drying at low temperatures (below 50°C) allows time for DM losses by respiration and enzymatic conversions. The most acceptable heat‐drying results have been obtained by drying for a short time at a high temperature (i.e. 100°C) and thereafter at a moderate temperature (i.e. 70°C).Changes in nonstructural carbohydrate concentrations occur during the storage of either freeze‐ or heat‐dried tissues. Thus, analyses should be conducted as soon as possible after tissue sampling. The least changes occur during storage in alcohol, following killing of the tissue i

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00733.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTA study of 16 silages made at the Hannah Research Institute and 22 silages made at the Grassland Research Institute showed highly significant positive relationships hetween the DM percentages of the material ensiled and the resultant silage. Using regression equations derived from this data, and from a record of the presence or absence of effluent, it was calculated that the average minimum DM content of herbage for ensiling which would produce no effluent was 22.9%. To ensure a margin of safety against production of effluent, a minimum DM content of 24.7% in the herbage was calculated from the confidence limits. To obtain this DM content, herhage will normally require wilting; effluent production should then be negligible.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00734.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTA series of eight fertilizer N rates, ranging from 0 to 377 kg N/ha per year, at increments of 53.8 kg N, was applied to a S170 tall fescue/SlOO white clover sward. The annual rates were split into 8, 6 or 4 equal dressings for harvests at intervals of 3, 4 and 6 weeks, respectively, over a 24‐week growth period from March to September, in each of two years. Residual harvests were taken 6 weeks later in October.Curves relating annual herbage yields to N rate were fitted to tbe data. Total herbage DM responses to 108 kg N/ha were small because of the typical white clover yield N rate interaction, but were almost linear from 108 to 323 kg N/ha at all harvesting frequencies. Tbe decline in rate of response at tbe bigher N application levels was less marked with frequent than with infrequent defoliation. Tall fescue DM responses were substantially linear from 0 to 323 kg N/ha. For the first and second years, relative DM yields of total herbage for harvesting frequencies of 3, 4 and 6 weeks were 100:108:120 and 100:111:131, respectively.Total herbage CP response curves were similar to those for DM, but continued to rise more steeply to the highest N rate tested, 377 kg N/ha. Tall fescue CP responses were linear from 0 to 377 kg N/ha. Harvesting frequency did not markedly influence CP yields.Total herbage DM yield was 14% less in the second year compared witb the first. The decline was due to a reduction in white clover, attributed mainly to the effect of repeated N applications, also the subsidiary effects of companion grass and weathe

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00735.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTA continuous digestibility trial, lasting 50 days with subperiods of 5 days each, was made with the spring regrowth ofEragrostis curvulagrown in the semi‐arid region of Argentina. Five sheep were used to measure the digestibility of DM, organic‐matter, cell‐wall contents and N. DM yield was estimated simultaneously. The fall in digestibility of all fractions examined was described by quadratic equations. Cell‐wall digestibility explained 91% of the variation in organic‐matter digestibility. The rate of decrease in crude‐protein digestibility increased with time and was particularly noticeable after about 40 days of growth. Digestible DM yield increased at a decreasing rate as maturity advanced, but digestible crude‐protein content decreased linearly throughout the trial. It is concluded that the optimum stage of maturity for weeping lovegrass utilization depends upon the performance required from the animals that are

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00736.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTIt has been shown in the past thatin vitrodigestibility of forage crops could be accurately predicted by the acetyl bromide absorption technique. This note demonstrates thatin vivodigestibility values can be accurately predicted by this method and that in this respect the method is comparable in accuracy with thein vitrodigestibility technique.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00737.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTAn electronic capacitance meter was used to estimate herbage yield from sown ranges in western USA. On an area in Arizona where the grass stand had heen sown broadcast, anr2of 0.47 was obtained between the meter value and oven‐dry weigbt estimate. Excluding tbose plots with very large amounts of standing dead organic matter (OM), or very succulent plants which had not been sown, improved yield estimates.Tests on pastures in Colorado in whicb seed had been drilled and tbe meter tested to evaluate performance in relation to drill rows showed that a common regression could be used for estimating yield. Metbods of placing the meter in relation to row directions are described which avoid a biased estimate of total pasture yield. Cutting the herbage in a 3‐dimensional manner improved ther2values over those obtained by the usual 2‐dimensional cutting procedure. Separation of dead OM from living plant material did not significantly change ther2values and showed that dead OM bad very little influence on the meter reading. This dead OM can contribute significantly to variation of the estimate about the regression line, however, and if differences in dead OM are substantial, sample sizes may need to be increased or sampling stratified to obtain an accurate yield estimate.Pertinent literature on the evolution of electronic capacitance instruments for estimating herbage yields has been presented in Part 1 of this series (3). Tbe present evaluation is restricted to the herbage yield estimates from mechanically sown pastures. The Neal Electronics Model 18–612 meter was used to make the yield es

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00738.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTStudy of the growth of heavily fertilized swards of S23 perennial ryegrass (Lolium perenne) at a hill and a lowland centre in mid‐Wales during 1968–69 demonstrated that lower productivity in the uplands could only be partially attributed to a shorter growing season and poorer summer growth conditions. Comparison of yields with potential transpiration estimates indicated that winter damage had an important bearing on production during the following year. In 1969, the adverse combination of a mild autumn and a severe winter led to a spring tiller density which was less than 25% of normal at the hill centre. With an annual fertilizer input of over 500 kg N/ha (480 lb N/ac) total DM production in 1968 and 1969 was 10.6 and 4.4 t/ha at the upland site compared with 14.8 and 10.1 t/ha in the lowlands (9450, 3920, 13,190 and 9000 lb/

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00739.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

ABSTRACTThe effects of 59, 118 or 177 kg N/ha were measured on 7 occasions from 8 to 57 days after application to a perennial ryegrass sward in terms of changes in composition.The first increase Dt of N significantly raised percentages of CP, non‐protein N, K, P, Ca, Na and Mg and significantly depressed percentages of DM, OM and OM digestihility. The second increment of N resulted in a further rise in the percentages of CP, true protein, non‐protein N, K, P, Ca, Na and Mg; the percentages of DM and OM were further depressed but OM digestihility was not significantly depressed. Percentages of P and Na showed increased responses for the more mature herbage; while percentage non‐protein N showed a more marked response in younger herbage. As herbage matured percentages of OM and Na rose, the latter only from days 16 to 45. All other attributes showed falling percentages to levels which could be inadequate for a 500 kg dairy cow yielding 15 kg milk. CP percentage reached this critical level (1.4% N) at days 37, 45 or 56 given 59, 118 or 177 kg N/ha; P percentage became critically low (<0.36%) at days 27, 35 or 38, respectively; Mg percentage fell to the critical level (0.12%) at days 23, 35 and 46. Na percentage showed the reverse trend, being deficient (<0.13%) in the earliest samples and becoming satisfactory from days 23 or 27 at 118 and 177 kg N/ha but it remained inadequate at 59 kg

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00740.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1973.tb00741.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY