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1.
To evaluate non-chemical strategies to control pasture-borne parasites in first-season grazing (FSG) cattle, a 3-year grazing trial was conducted during 2002-2004 on naturally infected pastures on a commercial beef cattle farm in Sweden. A uniform pasture was divided in 4 equal 2 ha paddocks onto each of which 10, 5-9 months old dairy breed steer calves were allocated at turn-out in May each year. Two strategies were evaluated: (1) turn-out onto pasture which had been grazed the previous year by second-season grazing (SSG) steers, followed by a move to aftermath in mid-July (RT) and (2) supplementation with concentrate and roughage for 4 weeks from turn-out (FD). Comparisons were made with an untreated (UT), and an anthelmintic treated control group (DO). Animal parasitology and performance were monitored monthly throughout the 20 weeks grazing period. Additional sampling occasions were performed on day 9 (for coccidia) and 10 weeks after turn-out (mid-July). Due to clinical parasitic gastro-enteritis (PGE), salvage treatments were performed on all animals in group FD approximately 7 weeks after turn-out in 2003 and of three animals in group UT 5 weeks after turn-out in 2004. In 2003, the geometric mean oocyst excretion 9 days after turn-out was approximately 150,000 opg of mainly Eimeria alabamensis in group FD, and in 2004 approximately 180,000 opg in group UT. Apart from the DO group, geometric mean faecal egg counts (FEC) were between 80 and 400 epg 4 weeks after turn-out. Mean serum pepsinogen concentrations (SPC) of approximately 3.6 U tyrosine were recorded in the FD and UT groups from late August 2002. In 2003 and 2004, mean concentrations in these groups were between 4.1 and 7.2 U tyrosine 8 weeks after turn-out. By the end of the three grazing seasons the average weight gain difference compared to the DO group was for FD -29, -38 and -5 kg and for RT -4, -21 and +14 kg, and compared to the UT group -18, +2 and +22 for FD and +7, +19 and +41 kg for group RT. In conclusion, the rotation control strategy showed promising results, whereas the strategic feeding was poor from a parasite control standpoint.  相似文献   

2.
A 3-year grazing trial was performed during 2003-2005 on a commercial steer-producing farm in Sweden to study performance of second-season grazing (SSG) cattle following different levels of parasite exposure during their first grazing season. Initially, groups of 10 first-season grazing (FSG) cattle were each year assigned to four parasite control strategies: (1) turn-out onto pasture that during the previous year was grazed by SSG cattle, followed by a mid-July move to aftermath, (2) supplementation with concentrate and roughage for 4 weeks after turn-out, (3) no treatment, or (4) anthelmintic treatment (injectable doramectin) every fourth week. All animals were set stocked, except for those in group one. Next spring and following housing the cattle were turned out for their second grazing season onto approximately 25 ha communal pasturelands as a common mob. Weighing, faecal sampling and blood collection were performed at turn-out and then every 4 weeks for the 20-week grazing season. Faecal samples were also collected on day 10 after turn-out for detection of coccidian oocysts. Antibodies to Dictyocaulus viviparus were analysed at the time of their second housing period, and when elevated levels were recorded, stored serum samples from seropositive animals were analysed retrospectively. Results showed early-season weight losses of up to 47 kg in the SSG cattle. However, faecal egg counts were generally low and there was no correlation between SSG performance and treatment history as FSG cattle. Still, cumulative egg counts were significantly higher in animals that had been treated with anthelmintic as FSG cattle but serum pepsinogen concentrations showed no significant differences and the output of Eimeria alabamensis oocysts seldom exceeded 10,000 oocysts per gram faeces. Antibodies to D. viviparus were observed from July 2004 and from June 2005 but not in 2003. In 2004 and 2005, 64% and 83% of the animals, respectively, were seropositive for D. viviparus. It is concluded that weight gain penalties resulting from different levels of parasite infections the first grazing season remained during the second grazing season in 2004 and 2005 but no differences in weight gain could be identified in SSG cattle that had experienced different parasite control measures during their first grazing season. This was under conditions where the level of pasture infectivity was low to moderate during the second grazing period. However, D. viviparus was demonstrated in SSG animals during the two last years of the study and was an important confounding factor.  相似文献   

3.
Spectral analysis was used to relate dietary quality and herbage species to the behavior of grazing steers. Four .3-ha paddocks were established with either 'AU-Triumph' tall fescue (F; Festuca arundinacea Schreb.), 'Apollo' alfalfa (A; Medicago sativa L.), 1/3 fescue and 2/3 alfalfa (2/3A), or 2/3 fescue and 1/3 alfalfa (1/3A). Each paddock was stocked with 10 to 16 steers and defoliated in 5 d. Three steers on each paddock carried vibracorders to monitor grazing time. Daily forage samples were taken in 10-cm layers and weighed. Esophageal extrusa were collected from fistulated steers to measure diet quality. Daily grazing time did not differ (P = .37) among treatments; however, steers grazing mixtures grazed numerically longer (1.4 h/d) than steers on monocultures. Spectral analysis revealed that steers grazing A and 2/3A had many daily meals of short duration, but steers grazing 1/3A and F consumed three meals daily at 8-h intervals. Throughout the 4.67-d grazing period, quality of the diet linearly declined in crude protein and herbage digestibility, linearly increased in neutral detergent fiber and cellulose, and exhibited quadratic changes in lignin and ash. For most quality values, the tall fescue monoculture differed from the others (P < .05). Steers selected diets with similar quality for the A, 2/3A, and 1/3A treatments. This study illustrates how differences in forage diets alter grazing behavior of steers.  相似文献   

4.
Dallisgrass (Paspalum dilatatum) is well adapted to the Black Belt physiographic region of the southeastern United States, and information on its productivity and nutritive quality as influenced by grazing management is needed. In a 2-yr grazing experiment, replicate 0.40-ha paddocks in established dallisgrass pasture were continuously stocked, or replicate 0.40-ha paddocks were subdivided into two 0.20-ha (RS2), three 0.13-ha (RS3), or four 0.10-ha (RS4) cells and rotationally stocked with yearling beef steers. Individual cells within the RS2, RS3, and RS4 treatments were stocked for 7 d followed by 7, 14, or 21 d of rest, respectively. In 2007, 3 Angus × Simmental crossbred steers (initial BW, 354 ± 6 kg) were assigned randomly to each paddock on July 16; in 2008, 3 Angus × Simmental crossbred steers (initial BW, 310 ± 6 kg) were assigned randomly to each paddock on July 14. In 2007, there was no effect (P = 0.25) of stocking treatment on ADG. Steers grazing RS4, RS2, and continuously stocked paddocks had 106 (P = 0.01), 86 (P = 0.03), and 83 (P = 0.03) kg greater total BW gain per ha, respectively, than steers grazing RS3 paddocks. In 2008, there were no differences among treatments in ADG (P = 0.43) or total BW gain per ha (P = 0.90). Correlation and regression analyses revealed positive associations between steer performance and forage concentration of CP, areal mass (kg/ha) of forage DM, and areal mass of forage CP. Results indicate that productivity and quality of dallisgrass for stocker cattle production were comparable between continuous and rotational-stocking methods.  相似文献   

5.
Abstract

Eight grazing systems were compared on irrigated Cynodon aethiopicus pastures which received 650 kg N, 36 kg P and 200 kg dolomitic limestone/ha, annually. There were either one, two, three, six or 18 paddocks in the systems, the single paddock system being continuously grazed. The others were rotational systems with various periods of grazing and of resting.

Using the comparative slaughter technique carcass mass gains of crossbred Hereford/Afrikaner steers were calculated. Three‐year mean carcass mass gains over stocking rates from 12 to 18 steers/ha ranged from 872 to 997 kg/ha. None of the rotational systems were better than continuous grazing.

Estimates of amounts of herbage available for grazing in each system showed that there was least in the continuous grazed and most in the multi‐paddock systems where there were long periods of rest between successive grazing.  相似文献   

6.
Patterns of herbage removal by rotationally stocked cattle (at a density of 4.85AUE ha-1) on initially structurally homogenous Tall Grassveld were examined over a single season. Three unreplicated camps were stocked early (29 days), at the recommended '10-15cm' sward height (44 days), and late (80 days) after a spring burn. Temporal change in the spatial distribution of herbage in each treatment was described by intensive measurement of compressed sward height (CSH) with a disc pasture meter and analysed with parametric and spatial statistics. Grazing pressure at the start of the grazing was highest in the early graze, intermediate at the recommended, and least in the late graze treatment because of variation in initial herbage mass related to period of deferment after the burn. The early graze paddock was most spatially uniform and the late graze paddock the most uneven and patchy before grazing. Such initial conditions significantly affected subsequent herbage removal patterns: the greater the amount and spatial variability of herbage accumulated before grazing, the greater the chance for patches to develop through area-selective grazing. The early graze paddock was utilised non-selectively during the first two grazing periods but similar to other treatments, became patchier with time. Spatial pattern, a mosaic of short, intermediate and tall patches, peaked in late summer and was most pronounced in the late graze treatment. Intensive, early stocking after a burn is recommended for minimising intraseasonal development of patches and efficient use of high-quality forage available after a burn.  相似文献   

7.
To evaluate the effect of gastrointestinal parasites on grazing behaviour, herbage intake and milk production in spring calving dairy cows, 12 naturally infected control cows were compared with 12 similar animals treated on three occasions (June, July and September) with eprinomectin. The cows were blocked according to calving date, parity, live weight and milk yield during week 2 after turnout and then allocated to the treatments. The grazing area was sub-divided into two sets of 12 replicated paddocks of equivalent size and topography. Pairs of either control or treated animals were randomly assigned to graze each paddock over the duration of the study. Within each plot, the pair of cows grazed a series of 1-day paddocks, of areas calculated to provide 72 kg of herbage dry matter measured to ground level. Faecal samples were collected from each cow in April, prior to allocation, and every 28 days thereafter. Samples were submitted for counts of nematode eggs (sensitivity 1 epg) and the presence of Dictyocaulus viviparus larvae. Additional faecal samples were taken on each occasion for culture and nematode identification. Pasture samples for direct larval counts were collected at the same time as faecal sampling. Behaviour measurements on all cows were made during three periods, once before the first treatment with eprinomectin and thence after the 2nd and 3rd treatments. During each behaviour measurement period, grazing and ruminating behaviour were recorded over two 24-h periods and measurements of components of short-term intake rate were made during a morning and a late afternoon grazing meal. Milk yield was recorded daily and milk quality was recorded weekly. Live weight and body condition score were recorded on the day of allocation, the day of initial treatment and thereafter at weekly intervals until the end of the trial. The parasitological results showed low levels of faecal egg output throughout the study with group arithmetic means ranging from 0 to 6.8 epg. Faecal culture yielded predominantly larvae of the genus Ostertagia, but the following genera were also identified: Cooperia, Oesophagostomum and Trichostrongylus. Pasture larval levels were also low with peak values of 135 and 58 L3/kg DM herbage (7 August) in the paddocks grazed by the control and treated cattle, respectively. Thereafter, larval counts on paddocks grazed by treated cows declined to undetectable levels by October, while control paddocks remained at approximately 40 L3/kg DM. There was no effect of treatment on components of grazing or ruminating behaviour recorded over 24 h or on short-term intake rates. There were significant differences between components of short-term intake rates measured during the morning and afternoon grazing meals. The overall milk yield response to treatment with eprinomectin was +1.68 kg/day solids-corrected milk (SCM) (P=0.026). The overall response included significant (P<0.050) increases in mean daily SCM yield following each of the three treatments, indicating a positive response to repeated treatments at several different stages of lactation. There were no significant differences in the overall percentages of fat, protein or lactose between control and treated groups. The differences in live weight were not significant, although there was a consistent pattern throughout for the treated cows to be heavier than the controls.  相似文献   

8.
Parasitic nematodes, even in the absence of any clinical disease, can cause a reduction in voluntary feed intake in housed ruminants. This trial examined these effects on young cattle grazing pastures. Twenty dairy heifer calves, born in the previous autumn, were blocked according to liveweight and allocated to one of two groups: either untreated or dosed with an IVOMEC((R)) (ivermectin) SR Bolus 10 days prior to turnout on 1 May 1998. The groups grazed separately on two paddocks on predominately ryegrass swards. Liveweights were recorded every 28 days and faecal samples taken for worm egg counts at the same time.In mid-May and mid-July, for two 14-day periods, animals were paired within treatment groups and transferred to one of 10 replicate paddocks of similar sward height and herbage mass. Grazing behaviour and herbage intake were measured during these periods.In mid-May, 2 weeks after turnout, treated and untreated animals showed no difference in grazing behaviour or daily intake of grass. By mid-July, 10 weeks after turnout, the untreated heifers spent on average 105min less per day in grazing time and their daily herbage intake was 0.78kg dry matter (DM) per day lower than that of the treated animals. Residual sward height, mass and composition in the trial paddocks reflected these differences. There were no clinical signs of gastrointestinal parasitism in the untreated group up to this time; in July, the mean worm egg count in this group was 120 eggs per gram (e.p.g.) of faeces. Faecal samples from several untreated animals were positive for lungworm larvae by July, mild clinical signs of bronchitis were observed in two of these animals in mid-July. Over the period from turnout until mid-July, the untreated heifers showed a reduction in mean daily liveweight gain of 150g, compared to the treated animals.  相似文献   

9.
The rapid increase of Poa pratensis L. (Kentucky bluegrass) on North Dakota grasslands during the past 30 yr has negatively impacted ecological services. Kentucky bluegrass grows earlier in the spring than many native grasses, which provides an opportunity to use targeted grazing to reduce Kentucky bluegrass and increase native grasses. A 5 year replicated study used 10 cow-calf pairs or pregnant cows to graze 3-ha paddocks in early to mid-May, early spring, (EARLY) until 30% of the native species were grazed. After 1 June, late spring−early summer, five cow-calf pairs were grazed on 3-ha paddocks (LATE) for twice as long as the EARLY treatment. Biomass was clipped inside and outside of cages after each grazing event and outside cages in the fall. In each paddock, a hundred 10-point frames were taken to determine percent native grass, Kentucky bluegrass, Bromus inermis Leyss. (smooth bromegrass), native forbs, and introduced forbs. After 5 yr, native grass abundance in the EARLY paddocks was 26% greater than in the LATE paddocks. Kentucky bluegrass abundance only differed the second year of the study when the EARLY paddocks had 32% less Kentucky bluegrass than the LATE paddocks. Total biomass was greater in the EARLY paddocks than LATE paddocks in year 2 of the study (886 ± 74 g m−2 vs. 608 ± 28 g m−2 for EARLY and LATE, respectively). Targeted grazing by cattle in early spring can increase native grass abundance and, depending on the year, decrease abundance of Kentucky bluegrass. Early spring targeted grazing should be used as a tool in adaptive management programs focusing on reduction of Kentucky bluegrass.  相似文献   

10.
Two trials evaluated the effects of a monensin ruminal delivery device (MRDD) on steers grazing winter wheat pasture. In Trial 1, 60 Hereford steers (initial wt 238.5 kg) grazed a 21.9-ha paddock of Vona-variety winter wheat for 112 d. Steers were assigned to either MRDD or control (C) treatments in a randomized complete block design. In Trial 2, eight ruminally cannulated steers (avg wt 234.4 kg) grazed a 2.4-ha paddock of Vona-variety wheat and were assigned randomly to either MRDD or C treatments. Three 11-d collection periods were conducted during early February, early March and early April. Chromic oxide was dosed to determine fecal output, and ruminal samples were collected on d 6 of each period. Nylon bags containing ground wheat forage were incubated ruminally beginning on d 8. In Trial 1, steers with MRDD tended (P less than .11) to gain more weight than C steers (.44 vs .38 kg/d). In Trial 2, wheat forage intake, in situ DM disappearance, ruminal pH, ruminal ammonia concentrations and ruminal proportions of acetate and total VFA concentrations were not affected by treatment. Ruminal proportions of propionate were increased (P less than .05) slightly by MRDD (20.3 and 19.2 mol/100 mol for MRDD and C, respectively). Butyrate proportions in ruminal samples were decreased (P less than .05) by MRDD during March but not in other sampling periods. Ruminal fluid chlorophyll concentration was less (P less than .05) for MRDD-treated vs C steers during early March but was greater (P less than .10) for MRDD-treated steers during early April. The MRDD shows promise as a method of supplying monensin to cattle grazing winter wheat forage.  相似文献   

11.
Investigations were carried out over three grazing seasons with parasitized and treated (control) steers on irrigated and non-irrigated upland and dikeland pastures. The stocking rate in each paddock was adjusted by either adding or removing animals so as to maintain as uniform a sward and rate of grazing as possible. Animals were weighed on and off the pastures and fortnightly during the grazing seasons.

During the first grazing season clinically normal steers shedding low numbers of gastrointestinal worm eggs contaminated the parasite-free pastures sufficiently to give rise to large residual pasture infections and clinical parasitic gastroenteritis in grazing stock during the second grazing season. Worm burdens of 100,000 to 200,000 Ostertagia ostertagi and Cooperia oncophora were established in several steers showing marked clinical signs. In spite of treatments with high dosages of thiabendazole in attempts to keep worm burdens at a minimum, there was a slow but gradual buildup of pasture infections in the paddocks grazed by the control steers over the three year period.

During the second and third grazing seasons there were significant differences in the daily rate of gain between the parasitized and control animals on both upland and dikeland pastures. The parasitized groups of steers had daily rates of gain ranging from 0.29 to 0.80 pounds less than their comparable control groups.

Under Maritime conditions, irrigation did not have a consistent effect on weight gains and development of parasitism.

  相似文献   

12.
A method of sampling pasture to estimate the numbers of infective nematode larvae to which grazing cattle were exposed was based on the grazing patterns and behavioural activities of two groups of cattle and was compared with other sampling techniques. Each group of cattle consisted of six permanent members, two members fistulated at the oesophagus and one worm-free tracer calf. Grazing time and the area where grazing occurred was not significantly different for tracer calves, fistulated cattle and permanent group members, and there was no relationship between grazing time and the live weight of cattle. Grazing time, the percentage of paddock area grazed intensively and the percentage of the paddock not grazed varied with season. The most intensively grazed areas were always visited between first light and the first rest period during mid-morning, and the plant parts and pasture species eaten could easily be identified by visual examination of these areas of the paddock. Larval recoveries per 100 g pasture ingested were estimated for comparison with the grazing area method using two other manual pasture sampling methods, a sampling method using tracer calves and one using fistulated calves. Correlations between these methods were not consistent but indicated that, given the small number of data sets, all methods were sensitive enough to estimate larval availability on pasture with the exception of the tracer calf method in the overstocked 3.4-ha paddock.  相似文献   

13.
This study aimed to evaluate the hypothesis that mixed sequential grazing of dairy cows and breeding ewes is beneficial. During the seasons of spring–summer 2013 and autumn–winter 2013–2014, 12 (spring–summer) and 16 (autumn–winter) Holstein Friesian cows and 24 gestating (spring–summer) and lactating (autumn–winter) Pelibuey ewes grazed on six (spring–summer) and nine (autumn–winter) paddocks of alfalfa and orchard grass mixed pastures. The treatments “single species cow grazing” (CowG) and “mixed sequential grazing with ewes as followers of cows” (MixG) were evaluated, under a completely randomized design with two replicates per paddock. Herbage mass on offer (HO) and residual herbage mass (RH) were estimated by cutting samples. The estimate of herbage intake (HI) of cows was based on the use of internal and external markers; the apparent HI of ewes was calculated as the difference between HO (RH of cows) and RH. Even though HO was higher in CowG, the HI of cows was higher in MixG during spring–summer and similar in both treatments during autumn–winter, implying that in MixG the effects on the cows HI of higher alfalfa proportion and herbage accumulation rate evolving from lower residual herbage mass in the previous cycle counteracted that of a higher HO in CowG. The HI of ewes was sufficient to enable satisfactory performance as breeding ewes. Thus, the benefits of mixed sequential grazing arose from higher herbage accumulation, positive changes in botanical composition, and the achievement of sheep production without negative effects on the herbage intake of cows.  相似文献   

14.
The effect of an ivermectin sustained-release bolus (I-SRB) on the epidemiology of nematode parasites and on calf productivity was evaluated in a field trial under Northwestern European conditions. Twenty parasite-naive female Friesian calves (principals) aged 5–9 months were used together with six male Friesian tracer calves. Principal calves were allocated by restricted randomization on day 0 body weight to either an untreated control group or a group given one I-SRB, designed to deliver 12 mg ivermectin per day for 135 days, orally on day 0. Each group was grazed on adjacent paddocks, naturally contaminated with parasitic nematode larvae, from 13 May 1991 (day 0) until housing on 30 September (day 140). Body weights of principal calves were recorded and individual blood and faecal samples taken at regular intervals throughout the trial. Pasture nematode contamination was monitored by larval counts on herbage and by worm counts of tracer calves grazed on each paddock from day 126 to day 140. Nematode contamination levels on the control paddock did not rise until the end of the grazing season, as a result of a mid-summer drought period. The period of exposure to a high larval challenge was too short to provoke body weight losses and clinical parasitic gastroenteritis in control calves. Use of the I-SRB resulted in zero faecal egg counts of trichostrongyles during the whole pasture season, thereby preventing a build-up of parasitic gastrointestinal nematodes on pasture. During the second grazing season no signs of parasitic gastroenteritis were detected in any animal, but an outbreak of parasitic bronchitis (PB) was observed in both experimental groups, indicating that PB can occur in older cattle regardless of the control measures taken to prevent clinical parasitism during the first grazing season.  相似文献   

15.
Parasite-free pastures would improve cattle health and performance, resulting in possible economic return to producers. Our objective was to determine the effect of a single series of anthelmintic treatment of steers prior to stocking on Coastal bermudagrass pastures, during five consecutive summers, on the parasite burden in cattle. The site for this experiment had been conventionally cropped for several decades, with no exposure to cattle, and would be expected to be relatively free of nematode larvae. The experimental design was a randomized complete block (landscape features) with a split plot arrangement of treatments where main plots were pasture fertilization treatments (mineral, clover plus mineral, and broiler litter) and split plots were low and high forage mass. Anthelmintic treatment included pour-on ivermectin on day -21, albendazole on day -7, and injectable ivermectin 48 h prior to stocking of pastures, with the cattle remaining in drylot during the 48-h period prior to being placed on the experimental paddocks. All steers received only one series of treatments during any given year. Yearling Angus steers (Bos taurus) were managed in a put-and-take grazing system with three "tester" steers assigned to each paddock and "grazer" steers added or removed at 28-day intervals. From 1994 to 1998, steers grazed the paddocks for a 140-day period from mid May until early October each year. Fecal samples for worm egg counts were obtained on day 0 and at 28-day intervals, thereafter. On all sampling days after day 0, samples were obtained only from tester animals. Over the 5-year period, the mean eggs per gram of feces (epg) gradually increased from 0 (following treatment) to a mean of 2.2 (range from 0.7 to 3.0) by the end of the grazing season (the last sampling date) in October. Although the epg were not zero, they were below threshold levels that would allow development of a parasite burden in cattle. In traditional management systems, cattle graze parasite-contaminated pastures; therefore, parasites negatively impact growth and productivity throughout the entire grazing period. Periodic anthelmintic treatments simply give a temporary reprieve from those parasitic infections. Conceptually, using the current grazing system, it should be possible to maintain these pastures in a parasite-free status indefinitely; however, from a drug resistance perspective, it would be most applicable in sod-based rotation systems where cattle graze from two to five years before land is returned to row-crops. By removing the effect of parasites, cattle can grow without the physiological constraints that gastrointestinal parasites place on appetite, digestion, nutrient utilization, and general well being.  相似文献   

16.
Three grazing experiments were conducted to determine the effect of level of endophyte infection, rate of N fertilization of tall fescue grass, grazing period, and paddock exchange on selected chemical properties of four bovine carcass tissues. Samples of semitendinosus and longissimus muscle and of subcutaneous and perinephric adipose tissue were excised from the left side of each carcass. In Exp. 1, percentage of stearic acid was higher (P less than .05) and percentages of palmitoleic and oleic acid were lower (P less than .05) in all tissues from steers grazed on LELN Au-Triumph fescue than in tissues from steers grazed on LELN KY-31 fescue. Grazing periods of 175 or 245 d or paddock exchange (Exp. 2) had no significant effect on proximate composition of semitendinosus and longissimus muscles; however, moisture content was higher (P less than .05) in the semitendinosus muscle from steers grazed on 100% (100E) endophyte-infected KY-31 fescue. Forage treatment, grazing period, and paddock exchange (Exp. 2 and 3) had no significant effect on percentage of saturated fatty acids in the subcutaneous, semitendinosus, and longissimus tissue samples. In Exp. 2 and 3, percentages of saturated fatty acids were higher (P less than .05) in subcutaneous and perinephric adipose tissue samples from steers grazed on 100E than in samples from steers grazed on zero endophyte (OE) fescue.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

17.
Twenty-four yearling Boer x Spanish goats were used in a crossover experiment to determine the effects of tethering on herbage selection, intake and digestibility, grazing behavior, and energy expenditure (EE) with high-quality herbage. Four 0.72-ha paddocks of wheat (Triticum aestivum) and berseem clover (Trifolium alexandrium) were grazed in the spring. Each paddock hosted 6 animals, 3 with free movement and 3 attached to a 3-m tether that was moved daily and provided access to an area of 28.3 m(2). One animal of each treatment and paddock was used to determine herbage selection, fecal output, or grazing behavior and EE. Herbage DM mass in tethered areas before grazing averaged 2,649 and 2,981 kg/ha in periods 1 and 2, respectively. The CP concentration in ingesta was greater (P < 0.05; 23.1 and 20.3 +/- 0.82%) for free vs. tethered animals, although in vitro true DM digestion (75.7 and 76.5 +/- 1.20%, respectively) did not differ (P > 0.05) between treatments. Intake of ME based on in vitro true DM digestion and fecal output was greater (P < 0.05) for free vs. tethered animals (12.7 and 10.4 +/- 0.89 MJ/d). No treatment effects were observed (P > 0.05) for time spent ruminating or grazing (405 and 366 +/- 42.5 min/d, respectively), although mean EE was greater (P < 0.05) for free vs. tethered animals (633 and 512 +/- 27.4 kJ/kg of BW(0.75) for free and tethered, respectively), with differences (P < 0.05) between treatments at each hour of the day. Tethering animals may be acceptable to model those with free movement for some measures such as ingesta composition but appears inappropriate for others, such as energy metabolism.  相似文献   

18.
Helminth infection acquired by lambs grazing on pastures fertilised either by urban sewage sludge or cattle slurry were studied in temperate Central Western France. The aim was to assess the risk of larval cestodoses in lambs after sewage application and of digestive tract nematode infection following the slurry application. Twenty-six sheep were allocated on two paddocks of 0.7 ha, one fertilised with sludge and the other with cattle slurry. The delay between application and actual grazing was 6 weeks; grazing on these paddocks extended from mid July to beginning of November 2002. The herbage biomass was slightly increased in the sludge paddock but it did not result in an increase of lamb live weight, compared with the slurry paddock. The lambs did not acquire cysticercosis or any other larval cestodoses in the sewage sludge group and only very limited infections with Cooperia spp. and Nematodirus spp. were observed in the slurry group. It was concluded that in our conditions the helminth risk was extremely low and was not a cause of restriction of the use of these biowastes.  相似文献   

19.
The pre-weaning production of ewes and lambs in spring on pastures grazed during the previous autumn and early winter by either weaner sheep, adult sheep, or cattle was investigated together with estimating the benefits of pre- and post-lambing drenches to ewes. These treatments were compared with one in which parasitism was uncontrolled in ewes lambing on pastures grazed previously by untreated weaner sheep, and another where parasitism was suppressed by 2-weekly drenching of the weaner sheep and also of the ewes and their lambs. Prior grazing by cattle effectively eliminated infection of pastures with intestinal Trichostrongylus and Nematodirus spp, but less so for Ostertagia spp. Worthwhile reductions in contamination were also achieved by grazing by adult sheep compared with grazing by undrenched weaners. Despite differences in the parasitological status of the pastures, there were no indications that pre-weaning growth rates of lambs were affected. However, wool growth in ewes was reduced by 10 to 20% by parasite infection. Wool growth of ewes on pastures grazed by cattle during the pre-experimental period exceeded that on any other treatment, and was significantly greater than that of ewes on pastures grazed by undrenched weaners. There was no production benefit in giving a pre-lambing drench to ewes on plots contaminated by weaners, or in giving the additional post-lambing drench to ewes grazing on plots contaminated by weaners, adult sheep or cattle.  相似文献   

20.
AIM: To determine whether Brucella ovis can be transmitted from stag to stag by successive grazing of infected and noninfected stags in the same paddock, or by grazing infected and non-infected stags in adjacent paddocks. METHODS: Six red deer stags (Cervus elaphus) were artificially infected with B. ovis and 5 were confirmed to be shedding the organism in their semen. Infected stags alternated paddocks, and therefore grazing and wallows (successive grazing), once or twice weekly with 6 non-infected stags from 3 March to 18 August, 1999. Direct contact between the 2 groups of animals was prevented. The 2 groups alternated paddocks 32 times. Six other non-infected stags were grazed in a paddock adjacent to the infected stags throughout this period, separated by a standard deer fence. Non-infected stags were blood sampled at 2to 6-week intervals to test for B. ovis antibodies using a complement fixation test and an enzyme linked immunosorbent assay. RESULTS: No stag from either non-infected group became infected with B. ovis. CONCLUSIONS: The risk of stags becoming infected with B. ovis by successive grazing of the same paddock as, or by grazing in paddocks adjacent to, infected stags appears to be low. We conclude from this result, and similar experimental evidence and experience of this disease in sheep, that transmission of B. ovis requires animals to be grazed or confined together in a way that allows direct contact between animals. CLINICAL RELEVANCE: It is likely that infected and non-infected stags can be managed on the same property without transmission occurring between the groups, provided that they do not come into direct contact with one another.  相似文献   

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