化除宿营法建立人工草地研究

化除宿营法建植人工草地产草量高,建植第2年最高干物质产量达到23 270 kg/hm2。化除宿营法与化除免耕法建立人工草地在建植当年没有显著差异,但第2年化除宿营法比化除免耕法增产7 353 kg/hm2(P<0.01)。在草地建植当年和第2年,施肥对地上生物量没有明显影响。化除宿营法建立人工草地宿营强度达到4羊夜即可,第2年平均干物质产量达15 483 kg/hm2。在无人为干预的情况下,蒿类等不可食杂草迅速侵入,土壤肥力越高,扩散速度越快;不可食杂草比例超过50%后,草地基本没有利用价值,地上生物量也不再急剧下降。     

Effect of contamination of pasture with military explosives on grazing behaviour in sheep

Abstract

Ungulates grazing in military training areas may be exposed to non-combusted fragments of various explosives, among which 2-methyl-1,3,5-trinitrobenzene (TNT) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) are two of the most common. This study investigated if sheep react to their pastures being contaminated with TNT or HMX. The experiment was conducted in fenced-in study areas on grass-dominated pasture. The eight sheep studied did not differentiate between clean pasture and contaminated pasture when choosing freely between plots containing TNT, HMX or no contamination. The results indicate that sheep grazing military training areas are unlikely to have behavioural responses reducing time spent grazing sites where TNT or HMX are present as fragments in the field layer.     

Mineral status of beef cows and sheep on spring pasture fertilized with kieserite

The utilization of minerals in orchardgrass (Dactylis glomerata L.) fertilized with kieserite (2,240 kg/ha) was examined in spring with lactating beef cows and wether lambs. Kieserite increased the concentration of Mg in vegetative herbage from .22 to .29% ( P less than .01) and of S from .20 to .29% (P less than .01), with little effect on other minerals. Fertilization also increased (P less than .01) apparent absorptions of Mg and S by lambs fed cut orchardgrass, from 24.5 to 36.5% and from 58.6 to 66.9%, respectively, and increased (P less than .01) apparent Mg retention from +.16 to +.33 g/day. Fertilization did not affect dry matter digestibility or apparent absorption of N, Ca or P by lambs. composition of blood and saliva of beef cows grazing fertilized and unfertilized pastures was determined during a 2-week period in early spring. Cows grazing kieserite-treated pastures showed a small increase (P greater than .05) in serum Mg, ultrafiltrable Mg and red blood cell (RBC) Mg, and fewer cows on the fertilized pastures showed severe hypomagnesemia (less than 1.0 mg/100 ml) after the first day of grazing. The decline in blood Mg concentrations was not accompanied by hypocalcemia or by changes in serum Na or K concentrations, but serum inorganic P decreased (P less than .01) markedly during the first 10 days of grazing. Ultrafiltrable Ca in blood was affected by fertilizer and period, but it is questionable whether either ultrafiltrable Mg or Ca would provide a more sensitive index of mineral status than serum concentrations. Concentrations of K, NA and P in saliva were more susceptible to fertilizer and period effects than were concentrations in blood, although all values fell within a normal range. There was no evidence of an inverse relationship between serum Mg and concentration of K in saliva of cows after a change from a winter-type diet to spring herbage containing high levels of N and K.     

Seasonal influence on diet selection of sheep grazing a weedy dryland lucerne pasture

The experiment was conducted to determine the seasonal effects on the availability, chemical composition and digestibility of a grazing dry-land lucerne pasture, as measured on samples either collected by hand or with oesophageally fistulated (OF) sheep. The pasture was monitored monthly for a period of thirteen months. An overall mean amount of 647 kg DM ha^?1 of material was monitored during the experimental period. Lucerne, as a percentage of the total DM availability was relatively low (approximately 19%), probably due to the preference of sheep to select lucerne in spite of the other available material. Both the crude protein (CP) content and the organic matter (OM) digestibility of the samples showed a seasonal tendency with higher values during the winter and lower values during the summer. Mean OM, CP, organic matter digestibility (OMD), acid detergentfibre (ADF) and neutral detergent fibre (NDF) contents of 91.7%, 10.7%, 57.5%, 47.1% and 74.0%, respectively, were obtained with hand-clipped samples, while the corresponding composition of samples collected by OF sheep was 83.1%, 21.0%, 64.7%, 38.2% and 58.4%, respectively. The sheep were able to select forage samples with a higher CP content than those collected by hand throughout the year. This was, however, not the case with the organic matter digestibility of the samples during the growing season July to October. The CP content of fistula extrusion samples (f) could be predicted from hand-clipped samples (h) from the linear relationship, CP_f = 10.51 + 0.97CP_h (r = 0.59). The study provided figures on the chemical composition and digestibility of dryland lucerne pasture at grazing in a Mediterranean environment.     

Observations on the indirect transmission of virulent ovine footrot in sheep yards and its spread in sheep on unimproved pasture

SUMMARY: Virulent ovine footrot was transmitted accidentally to a group of 23 adult Merino sheep (flock B) after holding for 1 hour in sheep yards, which earlier the same day had contained another flock (flock A) with < 1% prevalence of sheep with footrot lesions. Sheep in flock B were rendered susceptible to virulent footrot by grazing 600 mm high unimproved pasture dominated by paspalum ( Paspalum dilatatum ) and kangaroo grass ( Themeda australis ) during warm, humid and wet weather. In addition to moisture, interdigital abrasions caused by the pasture might have predisposed the interdigital skin to infection with Dichelobacter nodosus .     

Blood thiamine levels in normal cattle and sheep at pasture

Analysis of whole blood samples from 174 cattle and 174 sheep from 3 geographical regions of New Zealand over a 10 month period showed a mean (range) thiamine level of 122 nmol/l (71–237 nmol/l) for cattle and 118 nmol/l (67–227 nmol/l) for sheep. Regional and seasonal differences were noted with levels tending to rise over the summer period. A reference range of 75–185 nmol/l is proposed for both cattle and sheep to cover these variations. Levels below 50 nmol/l are considered indicative of deficiency.     

Blood thiamine levels in normal cattle and sheep at pasture

Analysis of whole blood samples from 174 cattle and, 174 sheep from 3 geographical regions of New Zealand over a 10 month period showed a mean (range) thiamine level of 122 nmol/l (71-237 nmol/l) for cattle and 118 nmol/l (67-227 nmol/l) for sheep. Regional and seasonal differences were noted with levels tending to rise over the summer period. A reference range of 75-185 nmol/l is proposed for both cattle and sheep to cover these variations. Levels below 50 nmol/l are considered indicative of deficiency.     

Relationship of pasture rotation to acquisition of gastrointestinal nematodes by sheep.

In a study of the relationship between pasture rotation in Illinois and acquisition of nematodes (mostly Haemonchus contortus) and body weight gains by lambs grazing with their ewes, 2 pasture rotation systems were tested. (1) Lambs and ewes were rotated through a series of 12 alfalfa-bromegrass-lespedeza pastures, each pasture being grazed for 3 to 4 days and rested for 5.5 weeks; 4 complete rotations were done during a 168-day grazing season. (2) Lambs and ewes were moved every 2 days, and 3 complete rotations of 50, 42, and 54 days, respectively, were done during the 146-day grazing season. The lambs under rotation had more nematodes and gained less weight than nonrotated control lambs, although rotation increased the amount of pasturage. Rotation is not recommended to control nematode parasitism of sheep in Illinois.     

Effect of sorghum grain supplementation on glucose metabolism in cattle and sheep fed temperate pasture

The aim of this work was to evaluate the effect of sorghum grain supplementation on plasma glucose, insulin and glucagon concentrations, and hepatic mRNA concentrations of insulin receptor (INSR), pyruvate carboxylase (PC), and phosphoenolpyruvate carboxykinase (PCK1) mRNA and their association with nutrient intake, digestion and rumen volatile fatty acids (VFA) in cattle and sheep fed a fresh temperate pasture. Twelve Hereford × Aberdeen Angus heifers and 12 Corriedale × Milchschaf wethers in positive energy balance were assigned within each species to one of two treatments (n = 6 per treatment within specie): non‐supplemented or supplemented with sorghum grain at 15 g/kg of their body weight (BW). Supplemented cattle had greater plasma glucose concentrations, decreased plasma glucagon concentrations and tended to have greater plasma insulin and insulin‐to‐glucagon ratio than non‐supplemented ones. Hepatic expression of INSR and PC mRNA did not differ between treatments but PCK1 mRNA was less in supplemented than non‐supplemented cattle. Supplemented sheep tended to have greater plasma glucagon concentrations than non‐supplemented ones. Plasma glucose, insulin, insulin‐to‐glucagon ratio, and hepatic expression of INSR and PC mRNA did not differ between treatments, but PCK1 mRNA was less in supplemented than non‐supplemented sheep. The inclusion of sorghum grain in the diet decreased PCK1 mRNA but did not affect PC mRNA in both species; these effects were associated with changes in glucose and endocrine profiles in cattle but not in sheep. Results would suggest that sorghum grain supplementation of animals in positive energy balance (cattle and sheep) fed a fresh temperate pasture would modify hepatic metabolism to prioritize the use of propionate as a gluconeogenic precursor.     

Comparative study of gastrointestinal helminthiasis in sheep on 'clean' grazing and permanent pasture under field conditions

An investigation of sources of helminth infection was carried out on three flocks: a traditional permanent pasture flock (A), one operating a 'clean' grazing system (B), and an East of Scotland College flock (C) which had operated a clean grazing system for nine years. Ewe and lamb worm egg output and pasture larval levels were recorded and tracer lambs were grazed during July and August on each farm. Considerable contamination was present on farm B fields compared with farms A and C, which resulted in higher worm burdens in late summer in farm B tracer lambs and lower weight gains. The main source of this infection was thought to be ewe periparturient egg output, as 21 per cent of ewes had positive worm egg counts over the lambing period. Differences in management practices between farms B and C, eg, earlier stocking of farm B fields, were also considered contributory factors.     

Behaviour of goats, sheep and cattle on natural pasture in the sub-humid zone of West Africa

The behaviour of sheep, goats and cattle on a shrub and tree savannah in the sub-humid zone of West Africa was studied during the dry (February to May), rainy (June to September) and cool season (October to January). Two mature females per animal species were followed by two observers during 3 days per month and behaviour activities were recorded every 15 min of the daily grazing time. When browsing, the plant name, plant part and plant height reached during prehension were recorded. The distance travelled and the grazing circuits were recorded with a step counter and a Geographic Position System device. The knowledge of farmers concerning appreciated browse species relative to the browse species consumed by animals in the area was also investigated.

During the dry season sheep, goats and cattle spent around 25% of their time browsing and 20%, 16% and 31%, respectively, of their time grazing. During the cool season, goats (17%) browsed more than sheep (7%) and cattle (5%) (P < 0.05). During the rainy season, sheep browsed 20% of the time while cattle spent only 7% of their time browsing, while goats were tied, with no opportunity for browsing. Browsing leaves was the most important part of the browsing activity. During the cool season, browsing height was the same (1.0 m) for cattle and goats, but lower for sheep (0.6 m) (P < 0.05). In the dry and cool season, sheep and goats walked shorter distances than cattle.

The plant species with the highest frequency of consumption were Acacia dudgeoni Craib, Ficus gnaphalocarpa (Miq.) A. Rich, Dioscorea togoensis Knuth, Cordia myxa L., and Manguifera indica L. for sheep and goats and Afzelia africana Sm., Kaya senegalensis (Desv.) A. Juss, Pterocarpus erinaceus Poir. and Dicrostachys cinerea (L.) Wight and Arn. for cattle. Species with a high frequency of citation by farmers were A. africana (92%), K. senegalensis (88%), P. erinaceus (86%), Faidherbia albida A. Chevalier (80%), A. dudgeoni (70%) and F. gnaphalocarpa (69%).

In conclusion, browse species make an important contribution to the diet of ruminant animals in the sub-humid zone and farmers are familiar with the species consumed by ruminant animals.     

羊粪对青海草地早熟禾草地生产力和土壤养分的影响

在三江源区果洛藏族自治州大武镇进行了青海草地早熟禾(Poa pratensis cv.Qinghai)小区施肥试验,研究了磷酸二铵、生羊粪、腐熟羊粪及不同施用量的腐熟羊粪对青海草地早熟禾牧草高度、盖度、密度、地上生物量及土壤养分的影响。结果表明,青海草地早熟禾在播种时用15 000 kg·hm-2的腐熟羊粪做基肥,其牧草高度、盖度、密度及地上生物量分别为69.5 cm、80.7%、6 190枝·m-2和 439.4 g·m-2,均可达到150 kg·hm-2的磷酸二铵施肥水平(P＞0.05)。 在相同施肥量下腐熟羊粪的增产效果明显优于生羊粪。土壤中有机质、全氮、速效氮、全磷和速效磷均随着腐熟羊粪施肥量的增加而增加。