The response of eragrostis cur vula to nitrogenous fertilizer

On the Transvaal Highveld studies were made of the response of Eragrostis curvula to applications of nitrogenous fertilizers. In one series of experiments nitrogen dressings were applied annually to a pasture over a period of 8 years. In a second series measurements were made of the effects of applying nitrogen to pastures of different ages. In both series increases were recorded in yield and in the protein content of the herbage.     

多年生黑麦草刈后再生草碳水化合物及氮素的变化

多年生黑麦草刈后2 d 内,其再生草各器官中的碳水化合物主要来源于残茬,刈后3 d内,再生器官中的氮素也是主要来源于残茬。刈前根部贮藏的碳水化合物和氮素对再生的贡献小于残茬。刈割3 d 后,根中新吸收的氮素和残茬内新同化的碳水化合物迅速增加,再生器官中,以新同化的碳水化合物和新吸收的氮素占绝对优势。在植株再生中,叶片生长区内刈前贮藏的碳水化合物和氮素下降的程度大于残茬和根部,其中,贮藏的氮素下降持续的时间长于贮藏的碳水化合物。高频率的刈割强烈地干扰了多年生黑麦草的能量贮藏和氮素平衡。     

The effect of defoliation and competition on the regrowth of Themeda triandra and Aristida junciformis subsp. junciformis

Abstract

The effects of a cutting trial, conducted to study the combined influence of defoliation and competition from surrounding vegetation on the vigour of Themeda triandra and Aristida junciformis, were evident after the single season of treatment implementation. Aristida junciformis was more sensitive to defoliation than T. triandra, whereas competition reduced yield to a greater extent in T. triandra than in A. junciformis. The two species differed in their ability to tolerate defoliation under competition. Defoliation reduced the yield of A. junciformis, at all levels of competition, to a greater extent than T. triandra. Aristida junciformis was particularly sensitive to a combination of severe defoliation and full competition. It is suggested that manipulation of grazing patterns may shift the competitive balance between palatable (e.g. T. triandra) and unpalatable (e.g. A. junciformis) components of the sward.     

Effect of the intensity and phenophase of defoliation and water stress on the rate of photosynthesis and the recovery of carbohydrate reserves in acacia karroo hayne

Abstract

A field study was conducted with Acacia karroo plants to determine changes in relative photosynthetic rates, the extent of carbohydrate reserve depletion and the rate reserves take to recover, following defoliation by goats at different intensities and phenophases, at a “wet” and a “dry” site.

The rate of photosynthesis of fully expanded leaves increased markedly following defoliation. Light defoliation increased photosynthetic rate the most. Total non‐structural carbohydrate levels dropped significantly after defoliation. The magnitude of decrease was directly related to the intensity of defoliation.

Following the heavy defoliations, recovery of carbohydrate levels was much faster than after the light defoliations. Rates of recovery were also faster following defoliation in the second half of the growing season, than in the first half. However, the plants that had been heavily defoliated in the second half of the growing season had not fully recovered carbohydrate levels before leaf fall in late autumn.

Moisture stress had very little effect on carbohydrate levels in comparison with the defoliation treatments.     

The utilisation of various fats by turkeys of different ages.

1. The utilisation of fat and fatty acids supplied as maize oil, tallow or lard in the diet of 2-, 4- and 8-week old turkeys has been investigated: a mixture of 10% fat and 15% cellulose replaced glucose monohydrate in a low-fat basal diet. 2. At 2 weeks of age the absorbabilities of the fats were 96, 57 and 91% for maize oil, tallow and lard respectively; at 4 and 8 weekds of age the corresponding figures were 97, 70 and 92% and 98, 74 and 90%. 3. The unsaturated fatty acids (18:1, 18:2) were highly absorbed from all fats; this was true also of the saturated acids (16:0, 18:0) in the maize oil, but in lard and, especially, tallow the absorbability of these fatty acids was lower. 4. The effect of age on the utilisation of tallow could be explained by the improvement in the absorption of these fatty acids. 5. The determined and calculated ME values of the fats are given.     

Energy utilisation of carbohydrate, fat and protein sources in newly hatched broiler chicks

1. TME, TMEn and metabolisability (TME/gross energy) of energy-yielding foodstuffs were determined in 1, 3 and 10 d old broiler chicks, using the assay method developed by Murakami et al. (1994), in order to characterise energy utilisation during the 10 d after hatching. 2. TME, TMEn and metabolisability of dextrin and starch were low in chicks aged 1 d, and increased with age up to 10 d. Energy values of glucose and maltose at days 1 and 3 could not be determined because of the sudden death of birds soon after the feeding. TMEn and metabolisability of cereal sources were lower in d-old chicks than in those aged 3 and 10 d. At all ages, maize was better utilised than wheat and sorghum. 3. In the fat sources (coconut oil, beef tallow and safflower oil) no age dependency was observed in TME, TMEn and metabolisability. 4. Bioavailability of soyabean meal and fish meal was lower at 1 d than at 3 d and 10 d. Energy utilisation from casein was the highest among the protein sources tested and it was not age dependent. 5. It is concluded that energy utilisation of carbohydrate and protein sources during 10 d post-hatch tended to increase with age. Among the energy yielding foodstuffs fat sources seem to be better utilised, with no age dependency.     

Effect of intensity and frequency of defoliation on aerial growth and carbohydrate reserve levels in Acacia karroo plants

Acacia karroo trees were defoliated by goats at two intensities and four frequencies; 2, 4, 8 and 12‐weekly. Leaf accumulation and carbohydrate reserve levels were compared to a non‐defoliated control, and to plants (defoliation controls) which were defoliated for the first time that season each time a frequency treatment was defoliated. These plants are activated by defoliation in such a manner that successive defoliations can result in this activation being additive. There is clearly a defoliation level below which they are not activated. Activation appears to be negated to a degree by defoliations at 2 and 4‐weekly frequencies, relative to the 8‐weekly defoliation frequency. The 12‐weekly frequency at heavy defoliation produced less than the same defoliation at 8‐weekly frequency. The 2‐weekly frequency treatments produced as much leaf as the 4 and 12‐weekly defoliations at the same defoliation intensity. The more frequently plants were defoliated, the more carbohydrate reserves dropped. However, plants adjusted to cope with very frequent defoliations. There was no connection between leaf accumulation and carbohydrate reserve levels following the different frequencies and intensities of defoliation.     

The response of Acacia karroo plants to defoliation by hand compared to defoliation by goats

Abstract

The leaf and shoot growth of Acacia karroo plants defoliated by goats was compared to that of plants in which leaf only or leaf plus shoot‐tips were removed by hand, to simulate goat browsing.

There were no differences in leaf or shoot production between plants whose leaf only was removed compared to those that had both leaf and shoot‐tips removed. Leaf growth on the plants defoliated by goats at moderate levels was approximately three‐fold that on plants defoliated moderately by hand. The plants defoliated by hand produced approximately twice the amount of leaf that the undefoliated plants produced. Heavy defoliation by both hand and goat, produced approximately half the leaf growth that moderately defoliated plants produced, following equivalent defoliation. Shoot production of all plants defoliated by hand was no different to that of the undefoliated control plants and was considerably less than that of the plants defoliated by goats.     

The regrowth of Colophospermum mopane following clearing

The recovery of cleared Colophospermum mopane thicket in the eastern Transvaal lowveld, to a level where its effect on grass production is similar to that in the pre‐cleared state, occurs within fourteen years. Based on certain assumptions, the ‘effective duration’ of the increase in grass production after clearing is about half of the recovery period. A model describing the recovery of basal area with time since clearing is presented. Simulations show that the recovery period is shortened by higher rainfall and lengthened by drought. It is hardly affected by the degree of clearing mortality typically achieved by the use of hormonal herbicides, but is extended to twenty‐two years if 90% mortality is achieved. Complete clearing mortality and a seedling establishment rate of four seedlings/ha/yearresults in recovery within forty years.     

Morphophysiology of forage peanut submitted to different intensities of defoliation on grazing with sheep

Tropical Animal Health and Production - The aim was to monitor the growth, the dry mass accumulation curve, and the structural photosynthetic components of forage peanut pasture, in different...     

The impact of body site, topical melatonin and brushing on hair regrowth after clipping normal Siberian Husky dogs

The aims of this study were to determine the impact of body site, vigorous brushing and topical melatonin treatment on hair regrowth after clipping normal dogs. Siberian Husky dogs were randomly assigned to three groups of eight dogs each. All dogs had the lumbosacral region and both lateral thighs clipped. The left thigh and lumbosacral area received no treatment and were compared in all 24 dogs. Eight dogs had the right thigh treated with 0.1% melatonin twice daily for 2 months, and hair regrowth was compared with the left thigh. Eight dogs had the right thigh brushed twice daily for 2 months, and hair regrowth was compared with the left thigh. Eight dogs had neither thigh treated. Hairs were plucked before and 2 months postclipping, and the proportion of hair growth from the original length was calculated and compared as described above. Biopsy samples were collected before and after treatment to determine if brushing induced dermal inflammation and melatonin increased the proportion of anagen follicles. Proportionally, left thigh hairs were significantly longer compared to lumbosacral hairs 2 months postclipping. No significant differences in hair regrowth were noted between the nontreated thigh and the thigh treated with melatonin or brushed. No significant difference in dermal inflammation was noted before and after brushing. No significant differences were observed in the proportion of anagen follicles before and after topical melatonin treatment. Our results showed that the hairs in the lumbosacral region were proportionally shorter than lateral thigh hairs 2 months postclipping. Moreover, topical melatonin and brushing had no impact on hair regrowth after clipping normal dogs.     

早期刈割对苜蓿再生性的影响

对苜蓿Medicago sativa进行早期刈割处理,以正常刈割时间(1/10开花期)为对照,设7个不同刈割时期进行刈割处理,测定与苜蓿生产性能和再生性相关的各项指标,研究早期刈割对苜蓿再生性和生产性能的影响,对不同时期刈割处理后的鲜草产量及其相关性状的动态变化进行测定.结果表明,不同刈割处理下苜蓿的再生性能存在明显差异,极早期刈割处理产草量最低;适宜刈割,也就是初花期刈割产草量最高.7个刈割处理生长性状动态变化为:株高在分枝期、孕蕾期、开花期有较大差异;除提前25 d刈割的处理外,其他各个处理的侧枝数、节间数差异较小;叶片数在不同生育期的动态变化为:分枝期不同处理间无差异,从孕蕾期到开花期处理间差异很明显;分枝数在整个生育期的不同处理间变化不是很显著;草产量与其相关性状株高和分枝数呈显著正相关.     

半秋眠和非秋眠紫花苜蓿生长规律及再生性研究

研究了半秋眠和非秋眠紫花苜蓿在上海的生长规律。结果表明:半秋眠和非秋眠紫花苜蓿月产草量呈现"双峰"型变化趋势,第一个高峰值在5月,非秋眠苜蓿的峰值持续到6月;4～6月是两类苜蓿生长较快的时期,期间的累计产草量占全年总产量的53.46%～65.2%;第二个生长高峰值出现在8月份,但明显小于第一个高峰值(p<0.05);7月份两类苜蓿的产量降至谷底,出明显的"夏眠"阶段;非秋眠品种的耐热能力高于半秋眠品种,月株高持续增长期比半秋眠品种长一个月,并且在"夏眠"后株高增加的幅度也高于半秋眠品种。     

不同SC/NSC日粮对徐淮白山羊瘤胃发酵的影响

选取4只体况良好、体重(30±2.5)kg的徐淮白山羊,并安装永久性瘤胃瘘管,按4×4拉丁方设计,饲喂4种结构性碳水化合物(SC)与非结构性碳水化合物(NSC)比例不同的日粮(SC/NSC3.52、2.06、1.28、0.84),分别为A、B、C、D组,研究徐淮白山羊瘤胃发酵规律.结果表明D组瘤胃液pH值极显著低于其他3组(P＜0.01);D组瘤胃液氨氮浓度(NH3-N)极显著高于A、B组(P＜0.01);A组微生物蛋白(MCP)浓度极显著低于其他3组(P＜0.01);瘤胃液总挥发性脂肪酸(VFA)、乙酸及丙酸浓度,C组最高,但差异不显著(P＞0.05);D组丁酸浓度极显著高于A、B、C三组(P＜0.01);乙酸与丙酸之比差异不显著(P＞0.05).结果表明,SC/Nsc为1.28时徐淮白山羊瘤胃发酵最佳.     

肉鸡开口日粮中使用不同蛋白质和碳水化合物对生产性能及胴体组成的影响

在过去10多年里,肉鸡的生长速度明显提高,达到屠宰体重标准的时间缩短,出壳后最初几天的表现更能代表一生的生产性能。在许多情况下,都会用到开口日粮,而且开口日粮更多的是被理解为一种前期投入,而不去考虑成本。对0～7日龄的肉鸡,最重要的是寻找能提高生产性能及相关胴体品质的高消化率原料,其次就是营养需要量的研究。对于刚出壳的小鸡,应该用一些不同于其他日龄的高消化率原料,因为它们的消化系统还不能完全适应对饲料进行消化并吸收。本试验研究了用不同碳水化合物和蛋白质原料的开口日粮对肉鸡生产性能、消化器官形态、胴体品质及产量的影响。开口日粮中的不同碳水化合物和蛋白质源的影响在生产后期并没有得到延续。     

Protein utilisation and turnover in lines of chickens selected for different aspects of body composition

1. Protein utilisation and turnover were measured in male chickens sampled from a line selected for high breast yield and a randombred control line (lines QL and CL, experiment 1) and in male chickens sampled from lines selected for either high or low abdominal fatness (lines FL and LL, experiment 2). In each experiment, 18 birds per line were given iso-energetic (12.9 MJME/kg) diets containing either 120 or 220 g CP/kg from 21 to 29 d (experiment 1) and 33 to 43 d (experiment 2). 2. Measurements were made of growth rate, food intake, body composition, excreta production and Ntau-methylhistidine excretion as a measure of myofibrillar protein breakdown, and fractional rates (%/d) of protein deposition, breakdown and synthesis were calculated. 3. In experiment 1, there were no significant differences between the line means for the fractional measures of protein turnover, but there was marked differential response in the two lines in the fractional rates of protein deposition, breakdown and synthesis, to increase in protein intake. The positive slope of the regressions of fractional (%/d) protein deposition and synthesis rates on protein intake (g/d/kg BW) were approximately 1.4- and 2.0-fold higher respectively in the QL than the CL line birds, and the negative slope of the regression of fractional breakdown rate on protein intake was approximately threefold greater in the CL than the QL line birds. 4. In experiment 2, fractional deposition rate was 6.2% lower, but fractional breakdown rate 9.4% higher in the LL than the FL birds, whilst there was essentially no difference in response of the FL and LL birds in the components of protein turnover to increase in protein intake. Line differences in deposition and breakdown rates were thus a reflection of the considerably higher (20%) food and hence protein intake in the FL than the LL birds. 5. The differential line responses in protein turnover in the two experiments suggest that selection for increased breast muscle yield and for reduced body fatness manipulate different physiological pathways in relation to protein turnover, but neither selection strategy results in an improvement in net protein utilisation at typical levels of protein intake by birds on commercial broiler diets, through a reduction in protein breakdown rate.     

不同刈割处理对苏丹草生产性能的影响

研究了不同留茬高度和刈割次数对苏丹草生产性能的影响。结果表明:在生育期间,随着刈割次数的增加,鲜、干草产量均以刈割2次为最高,分别达到95.05和20.46 t/hm2;不同留茬高度处理的鲜、干草产量,以留茬8 cm处理最高,分别达105.11和37.64 t/hm2,高于或低于8 cm留茬高度处理的茎叶比和产草量均与其差异显著(P<0.05)。     

The influence of nitrogen fertilization,spring burning and height of stubble on hay and seed production of eragrostis curvula 1

Abstract

This investigation, conducted over a three‐year period, emphasized the strong effect of nitrogen fertilization on both hay and seed production. The optimum level of nitrogen, for conditions on the Eastern Highveld being 100–150 kg N/ha applied in spring, followed by subsequent dressings dependent on rainfall. Although the influence of spring burning and stubble height on hay and seed production was not as consistent, both had a strong influence under certain conditions and with more research into their action could become important considerations in management strategies for Eragrostis curvula.     

Response of tall grassveld to different intensities,seasons and frequencies of clipping

The seasonal production of herbage by Tall. Grassveld declined with increased frequency of cutting in summer. Even a single summer cutting treatment reduced yields compared with no summer cutting. The effect of such a single cutting treatment varied, however, with the time at which it was applied. Early summer cutting reduced yields more than did late summer cutting.

Herbage yields declined as cutting height increased from 1½ to 4½ inches. This effect was associated with undesirable morphological changes in many of the constituent plants of the sward. High cutting induced tiller development at higher nodes than did low cutting, resulting in a lack of contact between the elevated tiller bases and the soil and in the elimination of differences between the proportions of each such tiller harvested and left by cutting to different heights.