A COMPARISON OF NUTRIENT LOSSES IN BALED HAY MADE FROM FORAGE-HARVESTED, CRIMPED OR TEDDED SWARDS WITH THOSE IN BARN-DRYING

Two experiments were conducted to study the effect on nutrient loss and feeding value of making hay by different means, using a barn-drier, a forage-harvester, a crimper and conventional tedding. Both forage-harvesting and crimping of the herbage significantly increased the rate of drying, compared with tedding alone. In Exp. 2 this effect enabled the crimped and forage-harvested hays to be baled for storage 3 days earlier than the tedded hay. The use of the forage-harvester significantly reduced the yield of herbage compared with conventional mowing. Nutrient losses from cutting until storage were highest for the forage-harvested hays, the loss of dry matter between cutting and storage in the forage-harvested hays being 39·9 and 19·3%, respectively, in Expt 1 and 2 with corresponding losses in the conventionally made hays of 7·1% and 9·3%. Crimping the hay resulted in higher nutrient losses than tedding. In Expt 2 there was a loss of dry matter of 17·5% in the conventionally made hay during an 18-week storage period, compared with 3·6% in barn-dried hay, 10·8% in forage-harvested hay and 8·8% in crimped hay.
In Expt 2, in which digestibility determinations were made, conservation decreased the total digestible nutrients and starch equivalent in all treatments. The use of the barn-drier gave the most efficient conservation of total digestible nutrients, followed by the crimped, forage-harvested and conventional treatments in that order. The starch equivalent values of hays made from the same sward were 43·0 when barn-dried, 39·8 when crimped, 38·6 after forage-harvesting and 31·6 after tedding.     

THE USE OF BARN-DRIED HAY AND SILAGE IN FATTENING YOUNG BEEF CATTLE

A series of trials was carried out in which barn-dried hay and silage were fed to young fattening cattle with or without supplementary barley. Liveweight-gains on silage and barn-dried hay alone were too low to provide an adequate finish during winter feeding. Liveweight-gains on hay alone were always higher than those obtained on silage alone, the difference being more marked in lighter animals. There was a marked response to supplements of 3 and 4 lb (1.4 and 1.8 kg) of barley, the response being significantly greater in silage-fed cattle than in those fed on barn-dried hay. There was some evidence of growth compensation with the introduction of a barley supplement to cattle on silage diets, but there was no such response in those fed on hay. Compensatory growth was not accompanied by improved digestibility or N retention.     

A COMPARISON OF SILAGE AND BARN-DRIED HAY FOR BEEF PRODUCTION

Three trials were carried out to compare the feeding value of silage and barn-dried hay for fattening bullocks of approximately 8 cwt initial body weight. In each case the silage and hay were cut from the same sward at the same time. In the first trial the bullocks fed on hay gained 1·88 lb/day while those self-fed on silage gained 1·55 lb/day during a 70-day feeding period. In the second trial of 70 days, the bullocks fed on hay gained 1·96 lb/day and those fed on silage from a trough gained 2·39 lb/day. In the third trial, individually-fed bullocks housed in stalls and given the same hay and silage as used in Trial 2 gained 123 lb/day on hay and 127 lb/day on silage. The significance of these results is discussed in relation to the findings of other workers.     

THE INTAKE OF HAY AND SILAGE BY COWS

Three comparisons were made, with non-lactating fistulated cows, of the voluntary intake of silage and hay prepared from similar herbage. On average 28% more dry matter was eaten as hay than as silage. Silage and hay had similar digestibilities, but silage residues tended to remain in the gut longer than those of hay. The amount of digesta in the reticulo-rumen immediately after a meal ad lib . was greater with hay than with silage. The cows spent longer eating and ruminating per kg dry matter of silage than of hay. The results are discussed in relation to possible factors determining the voluntary intake of silage.     

A COMPARISON OF TWO HAYS FOR BEEF PRODUCTION

A medium quality barn-dried hay and a poor quality field-cured hay were each supplemented with 3 levels of concentrate in the diet of young beef cattle, averaging 313 kg liveweight. The supplement was given on predetermined hay concentrate metabolizable energy (ME) ratios based on the determined ME of the hays and an assumed ME of 3·0 McalsAg DM for the supplement. The hay concentrate ratios used were 1:1, 1:2 and 1:3, the aim being to provide a reasonable rate of growth (0·7 kg/day) with the poorer hay. It was necessary to include urea in the concentrate mixtures used on the 1:1 and 1:2 ratios with the field-cured hay. The urea appeared to have an adverse effect on the intake and utilization of DM on the 1:1 ratio. The range of mean intakes of supplement DM was 3·02 to 4·41 kg/day for the barn-dried hay and 2·23 to 4·61 for the field-cured hay. Mean daily liveweight gains with the barn-dried hay were 0·76, 0·89 and 0·85 kg for the 1:1, 1:2 and 1:3 ratios, respectively, with no significant difference between ratios. The mean daily gains with the field-cured hay were 0·39, 0·77 and 0·75 for the three ratios, the mean gain on the 1:1 ratio being significantly lower than those of the other ratios. The ME conversion ratios were not significantly affected by either ratios or hay type, except on the 1:1 ratio with field-cured hay. There were significant differences between the barn-dried hay and field-cured hay diets in the digestibilities of DM, organic matter, crude protein and energy; the mean coefficients for DM being 74·5% and 65·6%, respectively.     

THE INFLUENCE OF SUPPLEMENTS OF FLAKED MAIZE ON THE DIGESTIBILITY BY STEERS OF SILAGE, FRESH LUCERNE AND LUCERNE HAY

Three experiments examine the effects of giving small supplements of flaked maize to steers on the digestibility and retention of nutrients from rations of grass silage, lucerne hay and fresh lucerne. The digestibility of the dry matter, crude fibre and crude protein of the silage ration was depressed by the successive additions of 1, 2 or 3 Ib flaked maize per day. There was a tendency for the steers to retain more nitrogen as the level of starch supplementation increased, in spite of a lowered crude-protein digestibility. The digestibilities of the constituents of lucerne hay and fresh lucerne were slightly increased by the addition of 2 and 4 Ib flaked maize per day. The reasons are discussed for the different effect of the supplemental starch on the digestibility of the crude fibre from grass silage and from fresh or cured lucerne. Attention is drawn to the increase in the retention of N following the supplementation of silage with starch.     

CHANGES IN CHEMICAL COMPOSITION AND THE LOSS OF NUTRIENTS IN TRIPODED AND SWATH-CURED HAY

The changes in chemical composition during haymaking, the loss of nutrients in the field and during storage, and the nutritive value of swath-cured and tripoded hay were compared. In good weather no advantage was gained by tripoding the hay. The nutritive value of the hays made by the two methods was similar and the loss of dry matter in the field slightly lower in the swath-cured hay. In a bad season, however, the nutrient loss in the swath-cured hay greatly exceeded that occurring in the tripoded hay and the starch equivalent, as shown by the results of digestibility trials, was markedly lower for the swath-cured.     

THE EFFECT OF MECHANICAL TREATMENT ON THE RATE OF DRYING AND LOSS OF NUTRIENTS IN HAY

Trials are described in which various mechanical treatments of hay in the field were compared. Cutting the crop with a forage harvester resulted in very rapid drying of the hay, but this was accompanied by very high nutrient losses. When the crop was tedded with the harvester the hay dried more quickly than with conventional ledding, the nutrient loss being similar for these two treatments. Tedding with either a harvester or a conventional machine appeared to increase the loss of nutrients compared with less severe treatment, but this loss appears to be acceptable as tedding considerably reduces the risk of the hay being weathered.     

The effect of propionic acid on the storage losses of hay

Storage losses in moist hay treated with propionic acid were compared with those occurring in untreated moist hay in two experiments and with field-cured hay in three experiments. Dry matter losses in treated hays ranged from 41 to 8.6% and from 1.7 to 12.6% in untreated hays. Digestible organic matter losses in both treated and untreated hays were generally greater than dry matter losses. Only in one experiment did propionic acid application significantly reduce nutrient losses in moist hays. Nutrient losses, and water-soluble carbohydrate losses in particular, were shown to be correlated with maximum and cumulative bale temperatures during storage in two of the experiments. The rise in hale temperatures during storage was reduced in all three experiments, to a greater or lesser extent, by application of the additive. Loss of propionic acid from the hay during and after application was very large. In the three experiments 86.2, 85.3 and 85.6% of the acid applied was lost by the end of the storage period. Acid distribution studies indicated that variation in acid concentration within bales was as great as between bales. It was concluded that more research is needed into applicator design and position on the baler and into alternative application methods if the benefits of propionic acid as a moist hay preservative are to be fully exploited.     

Evaluation of propionic acid-treated hay as a feed for growing sheep

Two experiments were carried out to evaluate propionic acid-treated hay as a feed for sheep in which eighteen ewes (experiment 1) and eighteen ewe lambs (experiment 2) were fed ad libitum on hay only. At feeding, the propionic acid-treated hays had higher D-values and water-soluble carbohydrate concentrations, but a lower dry matter concentration, than the untreated hays. The voluntary feed intake and liveweight gain of the sheep fed on two acid-treated hays and on an untreated hay in experiment 1 were similar. In the second experiment an acid-treated moist hay was eaten in greater amounts by the sheep and liveweight gains were greater than on the corresponding untreated hay, but were not significantly different from those of sheep fed on field-cured hay.     

THE ENERGY VALUE OF BARN-DRIED HAY

Recent publications dealing with the efficiency of utilization of dietary energy by ruminants suggest that metabolizable- and net-energy values may be calculated with reasonable precision from digestible-energy values. Use has been made here of existing data to estimate the metabolizable-energy (M. E.) and net-energy values for maintenance and fattening (N. E._m and N. E._f) of 5 samples of barn-dried hay of known in vivo digestibility, firstly to provide such figures for good quality barn-dried hays and, secondly, to illustrate a method of estimating energy values for hays that might be useful for routine advisory purposes.     

FACTORS AFFECTING THE VOLUNTARY INTAKE OF SILAGE AND HAY

Experiments with cows and sheep are described in which the voluntary intakes of hay and silage of differing digestibility were determined. The voluntary intake of hay increased consistently with increasing digestibility, but the relationship was not as well defined for silage. The addition of concentrates depressed the intake of hay, and this effect was more marked for hay with a high digestibility than with poorer quality hay. Concentrates appeared to depress the intake of hay by sheep more than by cows, an effect which was again more marked when the hay had a high digestibility value.     

EFFECTS OF FOLIAR APPLICATION OF COPPER SULPHATE ON THE COPPER CONTENT AND YIELD OF HAY

Foliar application of CUSO₄ to mature grass to increase the Cu content of the hay crop was markedly affected by rainfall within 24 h of the time of application. The mean Cu concentration of hay treated with 5·6 and 11·2 kg CuSO₄/ha was 100 and 208 ppm, respectively, when no rainfall occurred during this period, but only 24 and 41 ppm when rain fell within 24 h. Rain 4 or 5 days after spray application had no effect on the ultimate Cu concentration of the hay. It is suggested that sheep could safely graze the aftermath as, with one exception, concentrations of Cu found were only from 11·4 to 20·6 ppm. l±l kg CuSO₄/ha applied in dry conditions was sufficient to raise Cu concentrations in hay to levels which should preclude the occurrence of Cu deficiency when fed to cattle in winter. Reductions in hay yield following CUSO₄ applications in dry weather suggest a need to examine the use of more dilute sprays, or other means for increasing the Cu content of hay.     

THE EFFECT OF PRE-WILTING HERBAGE ON THE COMPOSITION OF SILAGE AND ITS INTAKE BY COWS

Lucerne was ensiled at various dry matter contents, within the range of 19·8% to 39·6%. An increase was found in lactic acid production, with a consequent decrease in volatile acid and volatile base content, up to the level of 33·9% dry matter.
The dry matter intake of cows was increased by feeding silage with a high dry matter content.     

THE EFFECT OF THE ADDITION OF ARACHIS OIL ON THE CONSERVATION OF HEAVILY–WILTED HERBAGE SEALED IN POLYTHENE FILM

A conservation experiment is described in which arachis oil was used to improve the energy content of heavily-wilted herbage of approximately 46% dry matter. The 2 oil-treated herbages and 2 control silages were enclosed in polythene film. The DM losses from all 4 silos were high compared with losses normally encountered in completely sealed silos. This is attributed to secondary fermentation which occurred after the silos were opened. The oil had a depressing effect on the digestibility of the mineral matter of both grass and silage. The metabolizable energy values of the silages are reported and discussed.     

FORAGE CONSERVATION IN THE TROPICS*

Under arid tropical conditions the natural grazing provides less than maintenance requirements for 8–9 months of the year. Conservation of natural or sown herbage, either as hay or silage, should be discouraged because of the low nutritive value of the product, and the unfavourable weather usually prevailing during conservation. Of the forage crops, cereal/legume mixtures are the most suitable for ensilage.     

A STUDY OF WILTING CONDITIONS IN SOUTH-WEST ENGLAND

Moisture losses from swaths of long herbage were recorded on eleven occasions in May, June and September, in order to supply data on which to base advice on making prewilted silage. Mowing in the late afternoon and picking up the following afternoon and mowing in the morning and picking up in mid-afternoon both resulted in losses averaging 9·6%. These losses occurred in fairly dry weather throughout the season, even when it was cloudy and cool. Mowing in the late afternoon and picking up next morning, before dew or overnight rain had evaporated, resulted in negligible losses, averaging only 2·4%.     

THE EFFECT OF ENSILING ON CROP DIGESTIBILITY

The digestibilities of 22 herbages, and of the silages made from them, were measured with sheep: in two experiments batches of the same herbage were ensiled by several different methods. In every case the digestibilities of herbage and of the corresponding silages were found to be very similar, and no significant effect of method of ensilage on digestibility was found. The importance of using the true dry-matter content of silages (i.e. corrected for losses of volatile constituents during drying) is emphasized; a depression in the digestibility of herbage during ensilage is likely to be estimated unless this correction is made. These experiments have shown that silage of high digestibility (>80%) can be made from highly digestible herbage; however the intakes, both of dry matter and of digestible dry matter, from such silages were found to be much lower than expected. If the potential for animal production of high digestibility in silage is to be exploited, intakes must be in-creased; two possible measures, viz. the wilting of herbage before ensilage, and the use of high-digestibility forages of high soluble carbohydrate contents, are discussed.     

THE EFFECT OF CONDITIONING ON THE RATE OF DRYING AND LOSS OF NUTRIENTS IN HAY

Treating cut herbage with a roller-crusher or a crimper resulted in an increased drying rate compared with tedding. A higher rate of drying was obtained when herbage was treated within a short period of the crop being cut, this effect being more marked with the crimper than with the tedder. Nutrient loss was higher when a crimper was used than with a roller-crusher or tedder. Applying water at an early stage in the drying process did not have a marked effect on nutrient loss, but appeared to decrease the digestibility of the crimped hay.     

美国高产优质青贮玉米杂交种的选育

总结粮饲兼用型、多叶型和棕色中脉型3种类型青贮玉米杂交种的特点。介绍青贮玉米产量和饲料营养价值的评价指标和方法,比较不同类型的青贮玉米种质资源的饲料营养价值和目前美国市场上最新的青贮玉米杂交种的农艺性状和品质性状。2010年美国德克萨斯州青贮玉米区域参试杂交种生物产量和干物质产量分别达78 210 kg/hm2和27 370 kg/hm2,淀粉含量平均为40.9%,中性洗涤纤维平均36.4%,总可消耗营养平均为75%。