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1.
Abstract

Two experiments designed to establish possible reasons for the often‐observed low voluntary feed intake of animals grazing kikuyu pastures were conducted at two widely differing locations. Low digestibility and low rate of digestion limited feed intake only when sheep were grazing dry, wilted kikuyu. At other times, rumen contents were relatively low, and voluntary intakes appeared to have been controlled by other factors. The foaminess of the rumen under circumstances of a low rumen fill seems to suggest that a high saponin content could have limited intake. However, the fact that a high rumen fill coincided with a high in vitro foam production in one instance may imply that a high saponin content was not instrumental in limiting intake. Only the rumen ammonia concentration and the total nitrogen content of the leaves showed a consistent relationship with voluntary intake.  相似文献   

2.
The seasonality of growth and low nutritional value of kikuyu (Pennisetum clandestinum) pasture restrict milk production. The aim of the study was to determine the dry matter yield, botanical composition and nutritional value of irrigated kikuyu over-sown with annual ryegrass (Lolium multiflorum var. westerwoldicum), white clover (Trifolium repens) and red clover (T. pratense) or a mixture of perennial ryegrass (Lolium perenne) with white and red clovers under intensive grazing conditions with dairy cows. The incorporation of annual ryegrass, perennial clover or perennial ryegrass–clover into kikuyu pasture changed the seasonal fodder flow and increased the spring dry matter (DM) production. The over-sowing of kikuyu with annual ryegrass had no effect on the DM production of kikuyu during the summer and autumn. Kikuyu and kikuyu–ryegrass, fertilised with nitrogen fertiliser, had a higher DM production rate than kikuyu–clover pastures. Kikuyu–ryegrass pasture transformed from ryegrass-dominant in spring to kikuyu-dominant in summer and only kikuyu in autumn. This led to a decrease in metabolisable energy (ME) and increase in neutral detergent fibre (NDF) content of the pasture during spring, summer and autumn as kikuyu became more dominant. The clover content of kikuyu over-sown with clover decreased annually but was still higher than 30% at the end of two years after establishment. As the kikuyu content of the kikuyu–clover pastures increased, the seasonal growth rate changed from a low autumn growth (37.9 kg DM ha?1 d?1) in the first year to a higher autumn growth (48.5 kg DM ha?1 d?1) in the second year. The over-sowing of kikuyu with clover resulted in lower DM production and NDF values and higher crude protein (CP), ME and calcium (Ca) values. The lowest CP content in kikuyu–ryegrass pasture was during summer and autumn when kikuyu was dominant. The Ca content of the grass pastures (kikuyu and kikuyu–ryegrass) was low. The phosphorus (P) content of both the kikuyu–clover and grass pastures exceeded the requirement needed for dairy production (0.38%). The mean Ca:P ratio of the kikuyu–clover pasture meets the 1.6:1 ratio needed by dairy cows. The kikuyu and kikuyu–ryegrass pasture had a Ca:P ratio lower than 1:1 and Ca supplementation would be needed for dairy cows. The incorporation of annual ryegrass, perennial clover or perennial ryegrass–clover into kikuyu pasture improved the seasonal DM production and nutritional value of the pasture.  相似文献   

3.
Abstract

An experiment was conducted on Smuts finger (Digitaria eriantha ssp. eriantha) and Kikuyu (Pennisetum clandestinum) pastures during a winter and spring period to study the effect of postruminal energy and/or protein supplementation on the selection pattern and performance of sheep. In a further experiment the digestion and utilization of these pastures were quantified. Voluntary intake on both pastures was not significantly affected by postruminal addition of casein but glucose tended to depress intake. In vitro digestibility of organic matter (IVDOM) and crude protein content of oesophageal samples were not significantly influenced by either casein or glucose. Consequently, it was concluded that postruminal amino acid and energy supply do not alter the quality of pasture selection but, depending on circumstances, the amount eaten may be affected. The amount of non‐ammonia nitrogen (NAN) in winter and spring samples flowing through the abomasum was proportional to the nitrogen (N) content in the grass organic matter (OM), while the volatile fatty acid (VFA) production was approximately associated with the digestible OM (DOM) intake. N retention on Smuts finger was significantly higher than on Kikuyu. One of the reasons appears to be less unavailable N in the cell wall of Smuts finger than in the cell wall of kikuyu grass.  相似文献   

4.
In this study, the effect of increasing the proportion of concentrate in the diet, on efficiency of feed utilisation, was determined when Holstein–Friesian cows grazed short-rotation ryegrass (Lolium multiflorum) or kikuyu (Pennisetum clandestinum) pastures. The concentrates were energy-dense dairy pellets fed twice-a-day at milking and the roughage component was lucerne hay and the pasture.When cows grazed ryegrass, there was no effect on animal performance as the proportion of concentrate in the diet increased from 0.23 to 0.35 (4.75 to 7.50 kg concentrate/cow/day). The substitution rate of concentrates for pasture for the first 1.57 kg concentrate/cow/day fed was 0.58 but rose to 1.18 for the next 1.28 kg concentrate/cow/day.When cows grazed kikuyu, there was also no effect of increasing the proportion of concentrate in the diet on total dry matter intake (DMI) or milk production. However, there was a substantial increase in the in vivo digestibility of whole diet, pasture and acid detergent fibre (ADF) was observed when the proportion of concentrate in the diet increased from 0.08 to 0.25. However, there was a marked decline in pasture digestibility (72% to 64%), and more so in ADF digestibility (61.3% to 48.4%), as the proportion of concentrate in the diet increased further to 0.29 (5.52 kg/cow/day). The intake of kikuyu, when determined by difference between pre- and post-grazing pasture mass, was substantially underestimated compared to the use of the n-alkane technique, and this discrepancy increased as the pasture on offer increased.On both pasture types, the neutral detergent fibre intake, as a % of bodyweight varying from 1.6% to 2.2% for kikuyu and 1.5% to 1.6% for ryegrass was far above the values claimed of 1.2% to restrict intake.The results of this study highlight the limits to the amount of concentrate that can be fed on a typical Australian dairy farm where concentrates can only be fed twice-a-day at milking. The results also provide a more appropriate benchmark for fibre limitation in the ration when cows graze pasture, particularly poorer quality tropical grasses, and this value is well above that found in more intense feeding situations.  相似文献   

5.
Perennial ryegrass is the primary forage component of ruminant diets in New Zealand. It is persistent and palatable, and immature ryegrass has a high nutritive value (NV). However, seed-head development substantially lowers its feeding value (FV) as fibre concentration increases, the rate and extent of digestibility decreases, and voluntary intake declines. Ryegrass pastures are susceptible to accumulation of endophytic and saprophytic fungi in dead material at the base of the sward, especially when mature and laxly grazed. Feeding forage legumes to ruminants grazing grass-dominant pastures will improve animal performance and lessen the reliance on a single species to meet all nutritional requirements.

The FV of forage is a function of intake and NV, measured by chemical analyses and animal feeding trials. Performance of individual animals grazing forages is usually limited by energy intake because structural fibre can slow digestion and clearance from the rumen and because of competition between individuals for available feed. The use of metabolisable energy (ME) content of forage to signify FV can give a reasonable indication of animal performance, but it should be used in conjunction with chemical analyses to improve the accuracy of predictions.

The relationship between FV, pasture production, animal performance and profitability is complex. The importance of skilled management to maintain pasture quality and optimise animal performance under inconsistent climatic conditions should not be underestimated. Acceptable animal performance with minimal veterinary intervention requires good nutrition, but the genetic potential of livestock in New Zealand cannot be met solely by grazing pasture, especially when a high utilisation of pasture is required to maintain quality and profitability.

Producers are responding to industry demands to reduce the seasonality in supply of milk and meat by changing lambing and calving dates, and extending lactation length in dairy cows. Social changes include adoption of once-daily milking in the dairy industry. Some changes have necessitated increased use of supplements and others can be met by feeding forages with a higher FV than ryegrass, all of which require an improved knowledge of feed quality. This information is available through rapid and inexpensive near infrared spectroscopy (NIRS) analysis, enabling animal nutritional needs to be balanced by appropriate nutrient supply. It is essential that producers continue to improve animal welfare, limit excessive use of fertilisers and meet the demands of overseas consumers. Good nutrition, with an increased use of legumes and other forages to complement ryegrass pastures, will enable these objectives to be achieved.  相似文献   

6.
This study examined the effects of adding forage legumes as protein supplements to poor-quality natural pasture (veld) hay offered to goats on microbial protein yield and nitrogen metabolism. Four indigenous Nguni-type goats were used in a 4×4 Latin cross-over design experiment. Goats were randomly allocated to four dietary treatments comprising commercial goat feed (GF), veld hay supplemented with cowpea (CW), velvetbean (VB) or silverleaf desmodium (SD). Microbial protein yields were determined using the purine derivatives technique and nitrogen retention was calculated from the digestible organic matter intake. Total nitrogen intake was significantly higher in the GF followed by CW, SD and VB, respectively. Microbial protein supply, calculated microbial true protein and digestible microbial true protein were affected (P<0.05) by legume supplementation. Animals on poor-quality forages had the most efficient microbial protein synthesis. However, supplementation of hay failed to meet the maintenance requirements of animals as evidenced by negative nitrogen balances in VB and SD. The efficiency of utilisation of nitrogen in the supplements could have been limited by unavailable fermentable metabolisable energy in the diets. Supplementation of poor-quality veld hay with legume forages could improve utilisation, especially in the dry season.  相似文献   

7.
The effect of yeast addition on intake and digestive utilization of pasture was studied in ovines under restricted time of access to forage. Eighteen wethers housed in metabolic cages and fed fresh forage (predominantly Lotus corniculatus) were randomly assigned to three treatments: forage available all day (AD); forage available only 6 h/day (R) and forage available only 6 h/day plus live Saccharomyces cerevisiae yeast (RY). Feed intake and digestibility, feeding behaviour, kinetics of passage, ruminal pH and ammonia concentration, nitrogen balance and microbial nitrogen synthesis (MNS) were determined in vivo, and ruminal liquor activity of animals was evaluated in vitro. Restricted animals consumed less than those fed all day but achieved more than 75% of the intake and spent less time ruminating (p = 0.014). Although animals without restriction consumed more feed, they had a lower rate of passage (p = 0.030). The addition of yeast did affect neither intake nor feeding behaviour, but increased digestibility. Organic matter digestibility tended to increase 11% by yeast addition (p = 0.051), mainly by a rise in NDF (27%, p = 0.032) and ADF digestibility (37%, p = 0.051). Ingested and retained N was lower in restricted animals, as MNS (p ≤ 0.045). The use of yeasts did not significantly change the N balance or MNS, but retained N tended to be higher in supplemented animals (p = 0.090). Neither ruminal pH nor ammonia concentrations were affected by the restriction, but restricted animals had a lower ruminal activity evidenced by a lower volume of gas (p = 0.020). The addition of yeast overcame this limitation, noted by a higher volume of gas of inocula from supplemented animals (p = 0.015). Yeast addition emerged as a useful tool to improve digestibility of forage cell walls in ovines under restricted time of access to forage.  相似文献   

8.
A wide range of management techniques is available to enhance quantity and quality of forage supply to grazing animals throughout the annual production cycle. Within broad limits, dry matter (DM) production is relatively insensitive to management of defoliation frequency, severity and duration. However defoliation management has effects on feed quality which can be enhanced, in particular, by control of pasture growth in the spring through maintenance of relatively low average pasture masses. Treading damage can have significant immediate and ongoing effects on pasture production and farmers can use a range of management techniques to minimise these.

Fertiliser application practices have a potent influence on pasture production and seasonality of that production. Available soil nitrogen is the primary nutrient deficiency limiting production in New Zealand's characteristically grass-dominant pastures. Nitrogen fertiliser usage has increased markedly in recent years, particularly to grow substantially greater amounts of forage during the cool season, and this trend looks set to continue. However, the use of nitrogen fertiliser has important environmental implications.

Pasture renewal and forage crop use has also increased in recent years. Care needs to be taken in conducting cost-benefit analyses, selecting the options that best meet the needs, and in establishment and subsequent management practices. Ryegrass (perennial and hybrids) and white clover remain the primary choice for permanent pasture renewal, the availability of safe endophytes having largely alleviated effects of endophyte toxicosis. Special-purpose mixtures are used, especially in dry environments. Italian ryegrasses, brassicas and chicory are common choices for forage crops. A range of management techniques can be used to alleviate deleterious effects of some forages, including ryegrass endophyte toxicosis, facial eczema, and toxins associated with Fusarium fungi. Generally these techniques are not totally effective. More research is required to increase our understanding of these disorders, and in order to develop more effective and reliable management practices.  相似文献   

9.
The effect of feeding forage legumes, Cowpea, Silverleaf desmodium and Oxley fine stem stylo, as protein supplements to natural pasture (veld) hay on intake, growth rate and nitrogen metabolism in growing lambs was evaluated. Thirty growing lambs were stratified according to body weight and randomly assigned, within a stratum, to five diets in a completely randomised design. The diets were veld hay alone (V), veld hay supplemented with either 10 g/kg of urea (VU), veld hay supplemented with 250 g/kg Cowpea (VC), 250 g/kg Silverleaf desmodium (VS) or 250 g/kg Oxley fine stem stylo (VF) forage legume hays. The V and the VU groups were used as control diets. Animals supplemented with either urea or the forage legume had higher (P < 0.01) total dry matter intake compared with the animals on V. The animals supplemented with the forage legumes had higher (P < 0.01) nitrogen intake and faecal nitrogen output than the non-supplemented group. All animals, across the treatments, lost body weight; lambs on V had higher (P < 0.01) body weight losses than those in the other treatments. The forage legume supplemented groups lost less (P < 0.01) body weight than those on the V and VU diets. Although supplementation with forage legumes enhanced feed intake and reduced weight losses it did not maintain body weights of lambs fed a basal diet of poor quality roughages.  相似文献   

10.
Abstract

Pasture sites for each of the species grown are classified for both dryland and irrigated pastures in the Natal Midlands. Only six species viz. kikuyu, Italian ryegrass, Eragrostis curvula, Festuca arundinacea (tall fescue), Dactylis glomerata (cocksfoot) and Trifolium repens (white clover) are widely used. Italian ryegrass pastures are grown almost exclusively under irrigation; clover is more widely used than is generally appreciated; a reasonably large proportion of E. curvula, cocksfoot and tall fescue pastures have a longevity in excess of 10 years; and the siting of pastures appears to be primarily a function of availability of suitable land and is Largely independent of soil type and aspect. Pastures are largely sited on high potential arable land, with little apparent trend towards intensification of steep non‐arable sites.

The survey suggests that research should be directed at a small number of important species rather than dissipated over many species which are unlikely to make any major contribution to pasture production.  相似文献   

11.
An experiment was carried out at Alemaya University in Ethiopia to investigate the effect of night kraaling on the dry matter intake (DMI), live weight gain (LWG) and foraging behaviour of Ogaden cattle. Three groups of four animals were given either 7 h access to pasture per day, simulating traditional grazing (TG) practice; extended grazing (EG) access for 11 h per day; or traditional grazing access plus a nocturnal forage supplement (TF). Live weight gain, DMI and foraging behaviour were measured during the late dry season (EP1) and the wet season (EP2). None of the treatments had any significant effect on either DMI or LWG during EP1 or EP2. Extending pasture access time from 7 h to 11 h did not significantly increase the amount time spent grazing, but grazing intensity was significantly (p < 0.05) reduced during the non-common grazing hours. Step rate was significantly lower (p < 0.01) during EP2 than during EP1 and bites per step were significantly higher (p < 0.001) during EP2 than EP1, indicating that animals had to travel a shorter distance before selecting material to eat during the wet season (EP2). Providing supplementary forage (TF) had no significant effect on any measured parameter. In this study neither of the two low-cost methods (EG and TF) of improving access to forage had any beneficial effect on cattle productivity. It is concluded that, under the prevailing conditions, the traditional grazing practices of this part of Ethiopia do provide sufficient pasture access time to achieve daily voluntary food intake.  相似文献   

12.
在牧草生长季节(5~9月)对小哨牧场放牧演替形成的5个草地型草地的牧草进行生长速率、牧草产量及养分的逐月观测,生长速率测定显示,白三叶+东非狼尾草和东非狼尾草+非洲狗尾草两个草地型草地均出现两个生长峰值,分别在6月和9月,其余3个草地型草地只有一个生长高峰。干物质产量和牧草养分测定结果表明,白三叶+东非狼尾草和白三叶+非洲狗尾草+画眉草两种草地型草地表现最好,可以在气候环境条件类似的地区推广种植利用;白三叶+画眉草和白三叶+非洲狗尾草两种草地型草地表现优良,可以在草地改良中,根据当地实际情况选择性地加以种植;东非狼尾草+非洲狗尾草型草地表现较差,不提倡种植。  相似文献   

13.
Abstract

The productivity of Trifolium repens L. cv. Ladino, under irrigation in the subtropical region of Gauteng, South Africa, is unknown. The performance of T. repens was determined over five years (1981/1982 to 1985/1986), at two defoliation frequencies, four levels of nitrogen (0, 400, 800 and 1 600 kg N ha?1 ‐ total applied over five years), and either the removal or recycling of harvested material. Frequent, compared to infrequent defoliation, resulted in higher dry matter (DM) yields from the second year onwards. Dry matter yields were positively affected by the recycling of material, compared to no recycling. A mean DM yield of 191 ha?1 in the first year and 12 t ha?1 in the final year, was obtained. The highest DM yields occurred during October for all years and lowest DM yields from January to March. The first and final year showed similar peaks (late October) and troughs (March till April). Crude protein (CP) content of the herbage was influenced more by frequency of defoliation than recycling of material, where the highest CP content in any year was obtained from frequent defoliation. Nitrogen fertiliser applied up to a total of 1 600 kg N ha?1 over five years had no effect on either DM yield or crude protein content. This study has shown that T. repens could be a productive pasture for at least five years in the subtropical region of Gauteng, South Africa. Productivity and quality of T. repens were enhanced by a defoliation interval of less than five weeks and when soil high fertility was maintained by recycled plant material.  相似文献   

14.
Abstract

On dryland Digitaria eriantha ammonium sulphate and limestone ammonium nitrate were superior to potassium nitrate and urea. With reference to the level of nitrogen fertilization it was found that levels in excess of 300 kg N/ha, and up to 400 kg N/ha, could be economically justified, even on a pasture with a high basal level of fertility.  相似文献   

15.
Fifteen cattle, with the typical copper deficiency symptoms of scouring and emaciation, gained .45 pound more daily after receiving copper injections than the control group in a three-month period. Copper injections did not prevent scouring on this ranch in the North Okanagan Valley. Copper deficiency symptoms have occurred in this area whenever cattle have been restricted to forage from ground-water soils though animals improve when moved to upland soils. Dairy calves and beef cattle are most frequently affected. Subclinical deficiencies may be more important economically than the easily recognized severe deficiencies.

The average copper level in pasture forage on this ranch was 10.2 ppm and copper content of forage was not related to scouring. The average molybdenum level was 8.8 ppm but the molybdenum content of 9.7 ppm in affected forage was high compared to 2.2 ppm in forage from a pasture where scouring did not occur and 4.2 ppm in pasture which caused less scouring. The average copper to molybdenum ratio was 1.0 in the affected forage which was low compared to the ratio of 4.3 in forage from the pasture where scouring did not occur and 2.3 in forage from the pasture where there was less scouring. Manganese tended to be higher in non-scouring forage. Sulphur contents were high but not related to the degree of scouring.

In a 1957 survey on farms not far from this ranch, no difference was found between the copper and molybdenum contents of scouring and non-scouring forage though copper was double and molybdenum comparable to levels found on this ranch. However, in the survey, scouring forage contained .65 per cent sulphur whereas non-scouring forage only contained .26 per cent.

  相似文献   

16.
本研究通过对返青期和盛草期牧场放牧的高山美利奴种公羊进行营养监测,旨在掌握高山美利奴种公羊放牧地牧草营养物质的季节变化规律以及高山美利奴种公羊营养的盈缺,为其科学饲养提供理论依据.选择6只成年、健康、体重[(104.94±5.15)kg]相近的高山美利奴种公羊作为试验动物,采用粪袋全收粪和盐酸不溶灰分(AIA)结合法测...  相似文献   

17.
Kikuyu pastures at the Ukulinga research farm near Pietermaritzburg were fertilized with 150 and 300 kg nitrogen (N) ha?1 in the summer periods of 1985–86 and 1986–87, and were continuously grazed with steers at stocking rates of 5.4, 8.0 and 10.7 steers ha?1. In the second season the high N level pasture was also grazed under 12‐paddock rotational grazing at stocking rates of 5.4, 8.0 and 13.4 steers ha?1. In the first season the high N level provided higher (P≤0.05) animal weight gains, but there was no difference between N levels in animal weight gain during the second season. Rotational grazing provided higher weight gains than continuous grazing in the second season. The increased weight gains obtained from high N fertilization and rotational grazing were probably caused by higher forage availability rather than higher forage quality.  相似文献   

18.
Perennial ryegrass is the primary forage component of ruminant diets in New Zealand. It is persistent and palatable, and immature ryegrass has a high nutritive value (NV). However, seedhead development substantially lowers its feeding value (FV) as fibre concentration increases, the rate and extent of digestibility decreases, and voluntary intake declines. Ryegrass pastures are susceptible to accumulation of endophytic and saprophytic fungi in dead material at the base of the sward, especially when mature and laxly grazed. Feeding forage legumes to ruminants grazing grass-dominant pastures will improve animal performance and lessen the reliance on a single species to meet all nutritional requirements. The FV of forage is a function of intake and NV, measured by chemical analyses and animal feeding trials. Performance of individual animals grazing forages is usually limited by energy intake because structural fibre can slow digestion and clearance from the rumen and because of competition between individuals for available feed. The use of metabolisable energy (ME) content of forage to signify FV can give a reasonable indication of animal performance, but it should be used in conjunction with chemical analyses to improve the accuracy of predictions. The relationship between FV, pasture production, animal performance and profitability is complex. The importance of skilled management to maintain pasture quality and optimise animal performance under inconsistent climatic conditions should not be underestimated. Acceptable animal performance with minimal veterinary intervention requires good nutrition, but the genetic potential of livestock in New Zealand cannot be met solely by grazing pasture, especially when a high utilisation of pasture is required to maintain quality and profitability. Producers are responding to industry demands to reduce the seasonality in supply of milk and meat by changing lambing and calving dates, and extending lactation length in dairy cows. Social changes include adoption of once-daily milking in the dairy industry. Some changes have necessitated increased use of supplements and others can be met by feeding forages with a higher FV than ryegrass, all of which require an improved knowledge of feed quality. This information is available through rapid and inexpensive near infrared spectroscopy (NIRS) analysis, enabling animal nutritional needs to be balanced by appropriate nutrient supply. It is essential that producers continue to improve animal welfare, limit excessive use of fertilisers and meet the demands of overseas consumers. Good nutrition, with an increased use of legumes and other forages to complement ryegrass pastures, will enable these objectives to be achieved.  相似文献   

19.
Abstract

The relationship between livemass gain and stocking rate was established for young beef animals grazing kikuyu and Coastcross II pastures in each of five grazing seasons. The annual rainfall within these seasons ranged from 506 mm to 990 mm. Relationships between pasture production variables and annual rainfall are described and these are used to construct a model for predicting livemass gain/ha/season for different stocking rates and levels of annual rainfall.  相似文献   

20.
牧草菊苣及其利用潜力 Ⅰ品种及生产性能   总被引：5，自引：0，他引：5  
王佺珍  崔健 《草业科学》2010,27(1):144-150
对菊苣Cichorium intybus的品种及生产性能进行了综述,菊苣是菊科菊苣属多年生宿根植物,在欧洲栽培甚多,其地上部分常被用作叶类蔬菜、牧草和饲料;地下根常用来制作咖啡替代品和制糖原料等。牧草菊苣是世界上许多国家畜牧业生产中的高产优质饲草。在中国,牧草菊苣主要品种有普那菊苣、欧洲菊苣、将军菊苣、欧宝菊苣、阔叶菊苣、益丰菊苣、杂交一代奇可利和甜心菊苣等,均表现出适应性强、生长供草期长、营养价值高、适口性好、抗病虫害能力强等高产优质特点,是目前我国较具发展前途的饲草作物兼经济作物之一。  相似文献   

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