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1.
On 81 farms blood samples were taken from adult dairy cattle, on pasture in October 1986 and after stabling in December 1986, to measure antibody titres against the nematodes Dictyocaulus viviparus, Cooperia spp. and Ostertagia spp., and the trematode Fasciola hepatica, and serum pepsinogen values. Faecal samples, collected in October, were examined to confirm the presence of parasites by means of egg counts and larval identifications. From December until the end of the stabling period, dry cows were either treated with albendazole or left untreated in alternate sequence of calving date. Treated cows produced 132.9 kg milk per cow per lactation more than untreated cows (P less than 0.01). Fat and protein percentage were not significantly influenced by anthelmintic treatment. The mean herd milk yield response to treatment varied from -889 to +1231 kg milk per cow per lactation. There was a significant between-herd variation in antibody titres against nematodes and in pepsinogen values. However no significant correlations between these parameters and the mean herd milk yield response to treatment were found.  相似文献   

2.
Liveweight of calves on 89 dairy farms was measured at the end of the grazing season and related per herd to the level of exposure to nematode infection during the grazing season. There were significant between-herd variations in antibody titres against Ostertagia spp., Cooperia spp. and Dictyocaulus viviparus as well as in pepsinogen values. All but six herds (93.1%) had gastrointestinal nematode infections, as measured by faecal egg counts in September. Faecal samples of 17 herds (19.3%) contained lungworm larvae in September. Liveweight of calves per herd deviated from -68.1 kg to +84.1 kg from the age-adjusted population mean after their first grazing season. Growth performance up to the time of liveweight measurements was significantly correlated negatively with several serological and parasitological parameters. Data could be fitted by means of both linear and segmented curvilinear regression. Antibody titre against Cooperia spp. and gastrointestinal nematode egg output measured in September accounted for 3.1% (P less than 0.10) and 6.7% (P less than 0.05), respectively, of the variation in growth performance among herds. Certain infection parameters, when combined, accounted for 9.2% of this variation; these were antibody titre against Cooperia spp. and larval counts for both gastrointestinal nematodes and lungworm. Adding certain management factors to these infection parameters resulted in a model explaining 27.6% of the observed variation in growth performance among herds. These factors were supplementary feeding, lungworm vaccination, anthelmintic treatment at housing, date of housing and herd age.  相似文献   

3.
Effect of ivermectin on performance of beef cattle on Georgia pastures   总被引：2，自引：0，他引：2  
A total of 469 cows and calves from 2 herds, each on 6 pastures, was used to evaluate the anthelmintic efficacy and animal-performance benefits of ivermectin given subcutaneously at a dosage of 200 micrograms/kg to nursing beef calves and their dams during a grazing season. Pastures were paired across the 2 herds. Three pasture groups from 1 herd were randomly assigned to either a nonmedicated control or to a medicated group. Treatment assignments were reversed in the other herd. The control groups comprised 110 cows and 108 calves, whereas 127 cows and 124 calves were treated with ivermectin (200 micrograms/kg). The cows were treated once, in late spring, and the calves were treated twice, once in late spring and again in midsummer. Cattle from one herd were weighed on days - 12, 21, 49, 77 (day of 2nd treatment for calves), and 105, and the other herd was weighed on days - 6, 23, 57, 86 (day of 2nd treatment for calves), and 113. Rectal fecal samples for nematode egg counts were obtained from approximately 25% of the cattle in each pasture on weighing days; usually, the same cattle were sampled each time. Calves treated with ivermectin gained (P less than 0.05) more weight than control calves up to the 2nd treatment date and up to the termination of the study. There was no significant difference between treated and control cows, with regard to weight gain over either interval. Treated calves had fewer positive fecal egg counts (P less than 0.01) and passed fewer eggs (P less than 0.05) after both treatments than did control calves. There were no differences in either number of eggs or number of negative cows between treatment groups. Adverse reactions attributable to treatment were not seen.  相似文献   

4.
SUMMARY A total of 498 dairy cows in 5 predominantly pasture-fed herds were allocated to pairs. One cow in each pair was treated with a single dose of ivermectin during the dry period. Treated and untreated cows were managed as a single group throughout the trial. Most cows calved between 45 and 115 days after treatment. When data from all herds were pooled, treated cows produced an extra 74 L of milk over the first 100 days of the subsequent lactation (95% confidence interval 20 to 128). Means were greater among treated groups relative to untreated groups in all 5 herds. However, when analysed individually, differences were statistically significant (P < 0.05) in 1 herd only. Over the complete lactation, mean milk volume for treated cows was 86 L greater than for untreated cows (95% confidence interval of difference -57 to 229; P = 0.24). Untreated cows produced 2473 L and 5883 L for the first 100 days of lactation and for the complete lactation, respectively. Milk production responses to treatment did not vary significantly with parity, body condition score, previous production index, calving date category or with plasma pepsinogen concentration or faecal egg count at the time of treatment. Faecal egg counts and plasma pepsinogen concentrations were low at the start of the study. The interval from calving to conception was 4.8 days less in treated cows (95% confidence interval 1.2 to 8.2) relative to untreated cows when data from all 5 herds were pooled. Differences within individual herds were not statistically significant.  相似文献   

5.
Growth performance of calves was assessed on 32 farms during winter housing. Nematode infection was measured by antibody titres, pepsinogen values, and faecal examinations. Half of each herd was treated with ivermectin after stabling. Treatment significantly increased growth rate by an average of +0.059 kg day-1 (P less than 0.01). The effect of treatment varied among herds from -0.078 to +0.210 kg day-1. Only a few of the infection parameters correlated weakly, but positively, to the effect of treatment on growth performance per herd. Untreated control groups showed very different growth rates among herds, ranging from 0.250 to 0.936 kg day-1. This was strongly correlated to several infection parameters. Groups with the highest values for the infection parameters gained approximately 50 kg less over a 4-month period during winter housing than groups with the lowest values for those infection parameters.  相似文献   

6.
Growth performance of calves was estimated by means of heart girth measurements on 48 farms during winter housing (from December to the end of March). Level of exposure to nematode infection was measured by antibody titres, pepsinogen values, and faecal examinations. Half of each herd was treated with albendazole after housing. All infection parameters measured in March were significantly lower in the treated groups than in the untreated control groups. Treatment increased growth rate by an average of +0.007 cm day-1 (N.S.), i.e. +0.036 kg day-1. Effect of treatment varied from -0.075 to +0.100 cm day-1 among herds. This effect of treatment on the growth performance was significantly correlated positively to pepsinogen value (r = 0.321, P less than 0.05 measured in October; r = 0.265, P less than 0.10 measured in December). Control groups showed very different growth rates among herds, ranging from 0.023 to 0.170 cm day-1, i.e. 0.112-0.874 kg day-1. This variation was strongly related to several infection parameters, particularly those measured in October. The most pronounced correlation was found between the average daily gain of the control groups and the mean herd antibody titre against Ostertagia spp. measured in October (r = -0.413, P less than 0.01). These results were consistent with those of a similar study conducted on commercial dairy farms a year earlier.  相似文献   

7.
The effect of nematode infections on growth performance during winter housing and on first lactation yield was investigated in heifers on 69 farms. Half of each herd was treated with albendazole after housing, which resulted in significantly reduced egg output, antibody titres against Ostertagia and Cooperia, and pepsinogen values compared with the untreated control groups. Albendazole-treated groups gained on average 0.007 cm day-1 heart girth (i.e. 0.05 kg day-1) more than control groups during the housing period (P less than or equal to 0.10), varying from -0.060 to +0.137 cm day-1 among herds. Albendazole-treated heifers produced 195.4 kg milk per 305-day lactation more than untreated heifers (P less than 0.01). Per herd, the mean milk yield response to treatment was +313.8 kg milk (P less than 0.01), varying from -876 to +1950 kg. Milk production of untreated heifers increased by 10.5 kg milk kg-1 extra body weight, adjusted for age, measured after the second grazing season (P less than 0.05). This suggests that nematode infections occurring in the first 2 years of life negatively influence milk production by reducing weight gains and hence body weight at calving.  相似文献   

8.
Antibody titres against Ostertagia spp., Cooperia spp. and Dictyocaulus viviparus as well as pepsinogen values, reflecting exposure to nematode infection, differed significantly among herds of second-year cattle on 87 farms. Faecal examinations revealed that gastrointestinal nematode infections were present in all herds. Similar results were found in yearling-herds on the same farms a year earlier. Liveweight of yearlings per herd deviated from -64.7 kg to +94.4 kg from an age-adjusted population mean after the second grazing season. This mean herd weight deviation was significantly related negatively to antibody titre against Ostertagia spp. (linear regression, P less than 0.05; segmented curvilinear regression, P less than 0.01) and to antibody titre against Cooperia spp. (segmented curvilinear regression, P less than 0.05), both measured in the second grazing season. Antibody titre against Ostertagia spp. measured in the first grazing season, when yearlings were calves, was significantly correlated positively to age-adjusted body weights at the end of the second grazing season. The results suggested that immunity built up during the first year had a positive effect on growth performance in the second year, but that on average the acquired immunity was insufficient to prevent reduced weight gains in the second grazing season.  相似文献   

9.
The efficacy of a treatment schedule using ivermectin, given subcutaneously at the rate of 200 micrograms kg-1, to control gastrointestinal parasitism and its effect on liveweight gains was assessed. Two herds with a total of 466 Hereford X Brangus cow/calf pairs were used. Each herd was on six pasture plots of comparable size, stocking rate, and quality and quantity of forage. Pasture groups were paired across the two herds. Pasture groups from one herd were randomly assigned to nonmedicated control and the other three to ivermectin treatment. Treatment assignments per pasture group were reversed in the other herd. The control group contained 118 cows and 112 calves and the medicated group 121 cows and 115 calves. Cows were treated in early July and the calves in late July or early August. Cattle from one herd were weighed on Days -28, 0 (day of cow treatment), 30 (day of calf treatment), 58, and 86, while the other herd was weighed on Days -29, 0 (day of cow treatment), 27 (day of calf treatment), 61, and 89. Day 0 was not the same calendar day for the two herds. Fecal samples for parasite egg counts were obtained from the rectum on weight days from five cows and six calves from each pasture; in most cases the same cattle were sampled each time. Calves treated with ivermectin gained (P less than 0.05) more weight than control calves between day of treatment for cows and the end of the trial.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
Ewes synchronised with progestin impregnated sponges to reduce the spread of lambing were treated during the periparturient period with anthelmintic. The suppression of nematode egg output in faeces was measured in ewes given ivermectin either by subcutaneous injection or orally, or oxfendazole or levamisole orally. Ivermectin and oxfendazole reduced the output of eggs in the faeces of the ewes significantly (P less than 0.05) and the period of suppressed egg output was extended when ivermectin was given by subcutaneous injection. Plasma pepsinogen activity was estimated as a measure of abomasal damage. Pepsinogen values were significantly (P less than 0.001) lower in those animals treated with ivermectin by subcutaneous injection than in control animals. Levamisole showed a poorer response in terms of the output of eggs in faeces than either ivermectin or oxfendazole.  相似文献   

11.
The suppression of nematode egg output in faeces was measured in ewes treated just before lambing with either oxfendazole or ivermectin by oral drench or with ivermectin by subcutaneous injection. Ivermectin and oxfendazole given orally were similarly effective, whereas ivermectin given by subcutaneous injection extended the period of suppressed egg output by about one week. The more persistent anthelmintic effect of ivermectin given subcutaneously was probably due to its extended half-life in the plasma of treated sheep. Plasma pepsinogen activity was less in the sheep given anthelmintic than in the untreated controls. Ivermectin caused a significantly greater reduction in pepsinogen activity than oxfendazole and was more effective when given subcutaneously than when given orally.  相似文献   

12.
Two trials with stabled milking cows were carried out. In the first trial, cows were either experimentally infected with Ostertagia ostertagi larvae or served as naturally-infected controls. In the second trial, cows were treated the same as in the first trial, but in addition half of the number of cows of each group were treated with oxfendazole before the trial started. The results showed that experimental infection influenced Ostertagia egg output, host serum pepsinogen levels and anti-Ostertagia antibody titres. The influence on egg output consisted of an initial decrease 1 week after infection, followed by an increase 3-7 weeks after infection. The pepsinogen level was significantly elevated after one week. The antibody titres increased from 3 weeks p.i. onwards. No influence on the milk production could be demonstrated. Naturally-infected controls also showed a rise in pepsinogen level and antibody titres, probably due to the existing worm burden. The egg output appeared to be influenced by the partus. Naturally-infected cows, treated with oxfendazole, showed no changes in any of the parameters during the trial.  相似文献   

13.
Liveweight of calves on 86 dairy farms was measured at the end of the grazing season and related per herd to the level of exposure to nematode infection estimated in October and December. There were significant between-herd variations in all the serological infection parameters measured. On average 20.5 larvae per gram faeces (geometric mean) were found in October. Faecal samples of 20.5% of the herds contained lungworm larvae. Liveweight of calves deviated per herd from -59.8 kg to +52.2 kg from an age-adjusted population mean after their first grazing season. Growth performance was significantly related negatively to several serological and parasitological parameters. Data were fitted by means of both linear and segmented curvilinear regression. By combining infection parameters 19% of the variation in growth performance among herds could be explained. Infection parameters involved were antibody titre against Cooperia spp., egg output and lungworm larval count. It was found that antibody titres were significantly correlated positively to herd age, while pepsinogen values and egg output were negatively correlated to age. Combining supplementary feeding and anthelmintic treatment during the grazing season with the infection parameters into one model explained approximately 30% of the observed variation in growth performance among herds. It was shown that these findings were consistent with those of a similar study conducted on the same farms a year earlier, although there were clear differences between the years. Finally, significant positive relations were found between the levels of exposure to nematode parasites within farms between two consecutive years.  相似文献   

14.
Twelve dairy herds that had participated in the Pennsylvania Dairy Herd Improvement Association (DHIA) program for at least 12 months, that had a 12-month mean DHIA somatic cell count greater than 700,000 cells/ml, and that had greater than 25% of lactating cows infected with Streptococcus agalactiae participated in a herd blitz treatment program. Initially, quarter milk samples for bacteriologic culturing were collected from all lactating cows. Subsequently, all cows identified as infected with Str agalactiae were treated, using a commercial penicillin-novobiocin intramammary infusion product. In addition, a herd mastitis management program of postmilking teat dipping and treatment of all cows at the start of the nonlactating period was instituted. Thirty days after the initial herd visit, samples from all lactating cows were again cultured, and cows infected at that time were treated. Twelve months after the initial herd visit, samples from all lactating cows were again cultured. Mean prevalence of infection with Str agalactiae decreased (P less than 0.05) from 23.0% of quarters and 41.6% of cows initially to 3.4% of quarters and 9.3% of cows at 30 days and 1.6% of quarters and 4.2% of cows at 1 year. Mean herd DHIA somatic cell count decreased (P less than 0.05) from 918,000 cells/ml initially to 439,000 cells/ml at 30 days and 268,000 cells/ml at 1 year.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

15.
The reproductive performance of beef cows and the weight gain of their calves was evaluated after oral administration of clorsulon or clorsulon in combination with the subcutaneous administration of ivermectin. One hundred and fifty pregnant cows harboring infections of Fasciola hepatica were assigned to one of three treatment groups: Group 1 comprising 50 unmedicated controls; Group 2, 50 cows treated with clorsulon orally at 7 mg kg-1; Group 3, 50 cows treated with clorsulon orally at 7 mg kg-1 and ivermectin subcutaneously at 200 micrograms kg-1. Weights and body condition scores of the cows were measured and fecal and blood samples were taken at trial initiation and days 158 and 270. Pregnancy status was also determined at day 270. Weights and body condition scores were measured for the calves at days 158 and 270. Adjusted 205 day weaning weight of the calves was calculated and analyzed for differences between treatment groups. Four sets of tracer calves were used periodically throughout the trial to monitor the helminth challenge to the herd. Both gastro-intestinal nematodes and liver flukes were transmitted to the tracer calves during the entire trial. Even in the face of continual helminth challenge, beef cows treated with combined clorsulon/ivermectin conceived approximately 2 weeks earlier than their untreated counterparts and their calves had better body condition scores and weights than untreated calves.  相似文献   

16.
Equine helminth infections: control by selective chemotherapy   总被引：3，自引：0，他引：3  
A programme of selective anthelmintic therapy was used in a herd of 31 horses. Faecal egg counts were done during the months of September, November, January, March, May and the following September. Horses with greater than or equal to 100 eggs per gram (epg) were treated with ivermectin, and those with less than 100 epg were not treated. The criteria for adequate internal parasite control in the herd was a median herd faecal egg count of less than or equal to 100 epg. Effectiveness of selective therapy was assessed by faecal egg count after nine months of treatment and was determined to be adequate when a median herd egg count of 0 epg was obtained. However, on returning from pasture the following September, median herd egg count had risen to 325 epg. A statistically significant correlation was seen in the paired September faecal egg counts of the horses in that initial September faecal egg count was predictive for the following September. Initial September faecal egg count was related to the number of anthelmintic treatments required during the period of selective therapy, whereas age of horse was not. We propose that faecal egg counts be incorporated into strategic anthelmintic programmes as an economical tool for identifying and targeting herd members predisposed to shedding elevated numbers of helminth eggs.  相似文献   

17.
Three anthelmintic pastes were compared in terms of their ability to suppress the output of parasite eggs in the faeces of 108 grazing horses at four sites in Britain; the horses were treated once with either ivermectin, fenbendazole or pyrantel. At each site, the horses grazed together throughout the trials which took place during the summers of 1985 and 1986. The median periods before parasite eggs reappeared in faeces were 70 days for ivermectin, 14 days for fenbendazole and 39 days for pyrantel embonate. Geometric mean faecal egg counts in the groups treated with ivermectin and pyrantel were significantly less (P less than 0.05) than in the fenbendazole group on days 21, 28, 35 and 42 after treatment. On days 49, 56, 63 and 70 the mean egg counts in the ivermectin group were significantly lower (P less than 0.05) than those in either of the other groups. The results indicated that in order to ensure minimal contamination of pastures, grazing horses treated with ivermectin paste would have required a second treatment approximately 10 weeks after the first, and to achieve similar control with fenbendazole or pyrantel embonate, a second treatment would have been required after approximately two weeks and six weeks, respectively.  相似文献   

18.
Forty spring-calving cows and heifers (20 of each) were allowed to acquire infection with gastrointestinal (GI) nematodes naturally during grazing. The control group (10 cows and 10 heifers) were compared with 20 similar animals treated with eprinomectin in order to evaluate the effect of GI nematodes on grazing behaviour, milk production, body condition score and live weight. The animals were paired according to parity and milk yield during the week prior to treatment, then within replicate pair randomly allocated to a different treatment group. The grazing area was sub-divided into 20 replicated paddocks of equivalent size and topography. Grazing pairs of either control or treated animals were randomly assigned to each paddock over the duration of the study (one pair per paddock). Grazing behaviour was recorded for both groups over a 10-day period commencing 4 days after treatment with eprinomectin. 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 4-week trial. Faecal samples were collected from each animal prior to, and after, allocation and submitted for counts of nematode eggs. Additional faecal samples were taken at the end of the study for culture and nematode identification. Individual faecal samples were also analysed for residual digestibility. Pasture samples for nematode larval counts were taken at the same time as faecal sampling. The parasitological results showed low levels of faecal nematode egg output throughout the study, with the heifers having higher counts than the cows. Faecal culture yielded species of Ostertagia, Cooperia, and Trichostrongylus. Pasture larval levels were very low throughout with no value exceeding 68 larvae/kg dry matter (DM) of herbage. There were significant (P < 0.05) effects of treatment on grazing time, eating time, total bites, total grazing jaw movements (TGJM), idling time and mean meal duration. Treated cows and heifers grazed for 47 and 50 min longer per day, respectively, than controls (P = 0.016). Mean meal duration was extended as a result of anthelmintic treatment by 11 and 38 min, in cows and heifers, respectively (P = 0.012). There were no significant (P > 0.05) treatment effects on ruminating time or residual faecal digestibility, but idling time was significantly reduced in both treated cows and heifers, by 50 and 110 min, respectively (P = 0.010). In the treated cattle, there was an increase in solids-corrected milk yield compared with the control cattle, which was significant (P < 0.05) in weeks 2 and 3 after treatment. The response was particularly marked in heifers, where the difference in yield between treated and controls was up to 2.35 kg/day. The differences in live weight gain and condition score over 28 days post-treatment were significant (P < 0.05) in both cows and heifers, in favour of the treated animals.  相似文献   

19.
Sub-clinical parasitism in spring-born single suckled beef calves was investigated from the middle of their first grazing season until weaning or housing later the same year. The study was conducted on four beef suckler herds in southern England over a 3-year period and involved a total of 334 spring-born beef suckler calves and their dams. The animals were grazed extensively on pastures naturally infected with nematode larvae. At the start of each period of observation, faecal samples were taken from calves and cows and subjected to routine worm egg counts; calves were re-sampled at the end of the grazing season.In July in each year and at each location the calves were ranked by initial weight within sex, paired according to rank and randomly allocated to either an untreated control group or a group in which the calves were each treated with an ivermectin sustained-release (SR) bolus. The calves in both trial groups, and their dams, were grazed together until weaning or housing. The calves were weighed at the initial allocation and at the end of the study. The adult cows were not treated with any anthelmintic during the study.The faecal nematode egg counts (FECs) conducted in July showed that the suckler cows were excreting worm eggs at low concentrations: range 0-100 eggs per gram (epg), with one individual count of 500epg, 88% of the cows sampled had counts of <50epg. Similarly, the counts from the calf samples were fairly low in July: range 0-250epg, 73% of the calves sampled had counts of <50epg. By the end of the grazing season, the faecal samples from the untreated control calves showed higher values: range 0-650epg, with only 58% having an epg of <50.The average rate of daily liveweight gain in the untreated heifer calves was 0.79kg per day, the corresponding figure for the heifer calves treated with the ivermectin SR bolus in mid-summer was 0.88kg per day; the difference of 90g per day was significantly different (P=0.0118). The average rate of daily liveweight gain in the untreated bull calves was 0.91kg per day, the corresponding figure for the bull calves treated with the ivermectin SR bolus in mid-summer was 1.01kg per day; the difference was significantly different (P=0.0169).  相似文献   

20.
SUMMARY Leptospirosis due to Leptospira interrogans serovar hardjo, occurred in a dairy herd of 104 cows and produced signs of mastitis, characterised by a sudden decrease in milk production and uniformly flaccid udders, in 11 cows. The microscopic agglutination (MA) test was used to determine antibody titres to serovar hardjo in all cows in the herd at 6, 33 and 63 weeks after the initial outbreak. The prevalence of MA antibodies to hardjo at week 6 was highest in cows in the youngest age groups and lowest in cows in the oldest age group. Over the 63-week period MA antibody titres to hardjo declined in 54 out of 62 seropositive cows, remained unchanged in 6 cows, and increased slightly in 2 cows. Fourteen of 59 cows (23.7%) with MA titres greater than 100 at week 6 had titres greater than 100 by week 63. Included in this group of 14 were 5 of 7 cows that had been affected with atypical mastitis. The distribution of serological titres to hardjo showed bimodal configurations at weeks 6 and 33 with the second peaks occurring at titres greater than 100, while the configuration was linear at week 63. MA titres to hardjo were also determined for 22 heifers 1, 16 and 36 weeks after they were added to the herd. No clinical signs of leptospirosis were observed in the heifers; however, the distribution of MA titres showed bimodal configurations at weeks 16 and 33 with second peaks occurring at titres greater than 100. Leptospiras were isolated from the urine of 2 seropositive heifers 16 weeks after their introduction to the herd, and cross-agglutinin absorption tests performed on one of the isolates indicated that it was identical to serovar hardjo.  相似文献   

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