THE EFFECT OF NITROGEN AND STOCKING RATE ON THE OUTPUT OF PASTURE GRAZED BY BEEF CATTLE

An experiment was conducted in two successire years to measure the effect of two levels of fertilizer N, 50 and 300 kg/ha (45 and 270 Ib/ac) on the productivity of pastures grazed by young beef cattle. Two stocking rates were imposed at the lower N level and 4 at the higher level. The responses per kg fertilizer N were approximately 1 kg liveweight gain, 20–24 Meal ME and 8–9 kg DM. Maximal yields of about 1000 kg gain/ha (890 Ib/ac) and 19,000 Meal ME/ha (7700 Mcal ME/acre) were recorded. Animal performance was similar on the low and the high N pastures. There was evidence that the chemical quality of pasture was lower on the low N pasture in the first year, but there was no difference in the second year. The numbers of dung pats per ha and the refusal of herbage due to fouling were reduced by Increasing the stocking rate.     

THE DECOMPOSITION OF CATTLE DUNG AND ITS EFFECT ON PASTURE

A total of 228 separate dung pats voided by lactating dairy cows between May and October on a ryegrass/dover sward were studied for 2 years. The pats were on grazed swards receiving, on average, either 440 or 110 lb N/ac (492 or 123 kg/ha) per year. The mean area of the pats was 0.62 ft² (0.058 m²) with no difference in area between the pats on the two N treatments. On average, the pats on the high- and the low-N treatments crumbled in 63 and 55 days, respectively, and disappeared in 115 and 113 days, respectively. Pats deposited in July disappeared significantly quicker than pats deposited in May. The average area of rejected herbage around the pats was 2.63 and 084 ft² (0.244 and 0.078 m²), respectively, 1–2 months, and 1 year after they were voided; but after 2 years the affected areas were recolonized with ryegrass and clover and were grazed normally. It is concluded that the levels of N fertilizer applied had no differential effects on the breakdown of the dung and on the subsequent recolonization of the affected areas by pasture plants.     

THE EFFECT OF HIGH NITROGEN LEVELS AND STOCKING RATES ON MILK OUTPUT FROM PASTURE

An experiment using 40 lactating dairy cows was conducted for 3 successive years to examine the effects of fertilizer N applied at 400 and 700 kg/ha (358 and 627 lb/ac) at stocking rates of 4.94 and 7.41 cows/ba (2 and 3 cows/ac). The animals were grazed in groups of 10 per treatment, using a fixed rotational grazing system, for 22 weeks in each year. Milk ontput/cow and/ha was significantly affected by stocking rate, the mean milk outputs being 2499 and 2218 kg/cow (5498 and 4880 lb/ cow) and 12313 and 16396 kg/ha (11032 and 14691 lb/ac) at the lower and higher stocking rates, respectively. Milk yield/cow at the lower stocking rate was not affected by N level. At tbe higher stocking rate, increasing the amount of N resulted in a 7.4% increase in milk output/cow and/ha. This response to N declined from 1.7% in the first year of the trial to 2.4% in the third year. The response in milk yield to N appeared to he greatest during the first part of the grazing season. Milk composition, liveweight change, and herbage availahilities and intakes were also recorded.     

THE RENOVATION OF DOWNLAND PERMANENT PASTURE II.

An experiment, A, involving dates and methods of application of 2,4-D (amine) as a preliminary treatment in the renovation of a poor downland permanent pasture, followed by surface cultivations and sowing of S.24 perennial ryegrass and S.100 white clover, was carried out at Hurley between 1953 and 1955.
In spite of initial differences in the establishment of S.24 and S.100, pre-treatment with herbicide had no effect upon the cover of sown and unsown perennial ryegrass and white clover two years later. At this date, perennial ryegrass contributed one-quarter and one-eighth, and white clover one-third and one-quarter, to the total cover of renovated and unrenovated plots respectively.
The increase in dry-matter yield resulting from renovation was approximately 10 per cent. This was considered small in relation to the estimated improvement in yield brought about by grazing management and manuring in the course of the trial.
In experiment B, plots receiving herbicide were given differential management and manurial treatments after spraying in an attempt to control the ingress of undesirable creeping grasses. The results indicated that this ingress could be checked by close grazing soon after spraying.     

THE EFFECT OF NITROGEN, STOCKING RATE AND FREQUENCY OF GRAZING BY BEEF CATTLE ON THE OUTPUT OF PASTURE

Two successive grazing experiments were conducted over 12 weeks on perennial ryegrass pastures with 50 and 44 young cattle to study the effect of N fertilizer when applied at a daily rate of 1 or 3 kg N/ha. At each level of N two stocking rates differing hy 20% were imposed. At the liigher N level and stocking rate, three frequencies of grazing were imposed. At the stocking rates imposed N tended to reduce the daily liveweight gain per head, but increased the total liveweight gain per ha by from 0.79 to 1.58 kg/kg N. A 20% increase in stocking rate depressed gain per head in both years. In the first year it did not improve gain/ha, hut in the second year gain/ha was increased by 12–17%. There was a tendency for performance per animal and per ha to increase as the grazing cycle was lengthened. In 1969 the highest yield in the whole season was 1880 grazing days and 1260 kg gain/ha. The overall response to N fertilizer was similar to that recorded in other reports, but it is possible that a lack of K had limited pasture growth.     

THE EFFECT OF NITROGEN, STOCKING RATE AND GRAZING METHOD ON THE OUTPUT OF PASTURE GRAZED BY BEEF CATTLE

An experiment was conducted in 1971 and 1972 to study the effects of two levels of fertilizer N (50 and 504 kg/ha) on the productivity of pastures grazed by young beef cattle. Two stocking rates were imposed at the lower N level and three at the higher. In addition to rotational grazing, set-stocking and an integrated grazing-conservation system were included. The responses/kg N were approximately 1 kg live-weight gain, 19–24 Meal ME and 8–9 kg DM. Maximum yields of 1200–1300 kg live-weight gain/ha and 25,000–27,000 Meal ME/ha were recorded. Productivity of set-stocked pasture was similar to rotational grazing at the high N level, but lower at low N. The integrated system yielded comparable results to high-N rotational grazing. Performances and herbage intakes per animal reflected the stocking rates imposed.     

SOME EFFECTS OF GRAZING MANAGEMENT ON THE YIELD AND ITS COMPONENTS OF SOME PASTURE GRASSES

A study was made to determine the effects of grazing to a height of 1 in. when the swards reached heights of 3 and 9 in. on the dry matter production, LAI, tillering and rate of leaf production of new and old tillers in the spring–summer and autumn–winter seasons of 3 pasture species growing in association with white and red clovers. In both seasons the herbage yield under 9–1 management was higher than that under 3–1 and was significantly greater in the spring-summer season. Differences in DM production between cocksfoot, tall fescue and Ariki ryegrass failed to reach significance.
Light utilization under the 2 management systems was considered to be inefficient. In the autumn-winter period there was a linear relationship between the LAI and DM production in all treatments.
The rate of leaf production per tiller was significantly higher in cocksfoot than in ryegrass and tall fescue in both seasons.
New tillers had a significantly higher rate of leaf production than old tillers in the spring-summer period, but not in autumn-winter. The numbers of grass tillers and rooted nodes of clover were significantly higher under 3–1 than under 9–1 and were influenced by season.     

A CORING TECHNIQUE FOR THE MEASUREMENT OF PASTURE OF LOW AVAILABILITY TO SHEEP

An account is given of a method for measuring short-grazed pastures. The procedure has particular value in studying the relationship of animal performance to pasture availability. A number of other pasture characteristics may be measured concurrently. These include species composition, tiller number and mean weight, stem-base material, roots, rhizomes and plant litter. The influence of core size and shape is studied and variance components reported.     

THE EFFECT OF DUNG AND URINE AND ITS INTERACTIONS WITH APPLIED NITROGEN, PHOSPHORUS AND POTASSIUM ON THE CHEMICAL COMPOSITION OF PASTURE

The importance of the grass/clover balance of a pasture in determining the effects of manurial returns and fertiliser applications on the chemical composition of the sward is shown.
The response to applied nitrogen was very dependent on the presence or absence of the animal excrements. For example, the N recovery from an application of 18 cwt. per acre of nitro-chalk was only 2% in the absence but 68% in the presence of the grazing animal.
Urine caused a marked increase in the N and K content and the yield of pasture, particularly when returned in quantity to a high-producing grass-dominant sward, and at the same time tended to depress the Ca, P and Mg content. Urine K was superior to fertiliser K, per pound of K returned or applied, in raising the K content of the pasture.
By comparison, dung had little direct effect on chemical content; even when returned in large amounts it affected the Ca and K content of the pasture to a relatively small extent. The P returned in the dung had little effect on the P content of the pasture and was inferior to superphosphate in this respect.
Together, as in normal grazing, dung and urine tended to counter or enhance their individual effects.
There was a positive correlation between the Mg and P content of the pasture and a negative correlation between Mg and K. Brief mention is made of the possible importance of the nutrient balance in pasture as a factor in animal health.     

COMPETITION BETWEEN WHEAT AND UNDERSOWN PASTURE IN THE YEAR OF SOWING AND THE EFFECT OF UNDERSOWING ON THE YIELD OF PASTURE IN THE FOLLOWING YEAR

Sowing pasture species with wheat caused a reduction in the growth and yield of the pasture species. This reduction was more severe with wheat drilled at 7 inch row spacing than at 14 in., and was least when the two crops were in alternate 7 in. rows. The reduction appeared to be due principally to the shade cast by the wheat. The pasture also reduced the growth and yield of wheat, but the effect of row spacing and position were opposite to and very much less marked than those of wheat on pasture. The yield of the pasture early in the following season was related to the seed yields in the year of establishment; later in the season, however, differences in yield among the various treatments disappeared.     

大批量小样品豆腐与豆乳得率的定量分析技术研究

豆腐与豆乳的育种和资源研究需要对大批量小样品进行得率的测定,为选择提供快速而又相对精确的依据.本研究目的是在前人基础上改进小样品豆腐与豆乳得率的实验室定量分析技术,进而提出精确、稳定、规范的测定流程.主要研究内容为以干磨代替湿磨,选用性能稳定可控性好的FOSS Tecator 1095样品磨,干磨豆粉;以6个百粒重差异较大的大豆品种为供试材料,分析不同磨豆时间、不同滤渣条件对小样品豆腐与豆乳得率的影响.结果表明,磨粉时间50 s,循环水式多用真空泵经120目滤网减压室温抽滤1 min的豆腐与豆乳得率最高,误差最低.提出以下流程作为规范化豆腐与豆乳得率实验室定量分析技术:精确称取经FOSS样品磨50 s磨碎的豆粉5.00g,以150 mL自来水室温浸泡2 h,采用循环水式多用真空泵经120目滤网减压(真空度0.098 Mpa)室温抽滤1 min,分取20 mL浆液烘干测干豆乳得率;另取20 mL浆液置于95℃水浴约15 min(浆面温度呈90℃)、冷却至约80℃加0.6 mLCaSO4过饱和溶液点浆,搅拌,蹲脑30 min,经16,000 r/min离心10 min,倾去上清液得湿豆腐,120℃烘干24 h测干豆腐得率.经大量实验验证,改进后的方法具有快速、精确、高效的优点.     

THE VISUAL ESTIMATION OF PASTURE AVAILABILITY USING STANDARD PASTURE CORES

A coring technique (6), that may be used for estimating the mean amount of herbage on closely grazed pastures, has been adapted to include visual scoring. Two methods are described, both of which use sets of pasture cores from the sward as reference standards. The observers score the herbage on view at random sites against the standards. In the first method the scores are converted to herbage yields directly by reference to the yields of the standards. In the second method a double sampling regression technique is used and the set of standards is used as a visual guide only.     

THE LOCAL INFLUENCE OF CATTLE DUNG AND URINE UPON THE YIELD AND BOTANICAL COMPOSITION OF PERMANENT PASTURE

A study was made of the local effects on yield and botanical composition of the herbage of cattle dung and urine applied to permanent pasture as simulated defaecations and urinations.
A single application of urine had a negligible effect upon botanical composition. In the 2-ft.-diameter circle around dung patches there was an increase in cocksfoot, creeping bent, red fescue and white clover, and a decrease in herbs.
Urine patches were neglected by grazing stock for short periods only. Herbage around dung patches was neglected for a period varying from 13–18 months. The effect of this neglect was to restrict the spread of white clover around dung patches in comparison with similar plots kept short by cutting.
Yield response to urine in the area of deposition lasted for two cuts following application, response to dung for four cuts. An increase in crude-protein content of the herbage was recorded only in samples taken one month after application of dung or urine, and not later.
Increases in crude-protein yield following spring applications of dung or urine were greater than those following autumn applications. The inferiority of autumn applications may be attributed to winter leaching of nitrogen.