Triclabendazole is currently the only single flukicide with licensed efficacy claims against all ... more Triclabendazole is currently the only single flukicide with licensed efficacy claims against all parasitic stages of Fasciola hepatica, including young immature flukes; it has been widely used in sheep and cattle for more than 30 years. Triclabendazole resistance was first confirmed in 1995 in Australia and since then has been reported in many other countries. Previous studies have shown synergy between triclabendazole and other flukicides against triclabendazoleresistant (TCBZ-R) liver fluke isolates. A study was conducted in sheep to investigate whether synergy exists between nitroxynil and triclabendazole, when administered at their recommended doses, in the treatment of early, immature (4-week-old) TCBZ-R F. hepatica infections. Lambs (68) were allocated by live weight to six groups and each animal was dosed with either 250 triclabendazole-susceptible (TCBZ-S) metacercariae (Groups 1 and 3) or 250 TCBZ-R metacercariae (Groups 2, 4, 5 and 6). Treatments were administered 28 days ...
The purpose of this study was to estimate and discuss the genetic variation, heritability, and ef... more The purpose of this study was to estimate and discuss the genetic variation, heritability, and effects of nongenetic factors on the ability of Holstein-Friesian cows to produce an immune response by producing IgG antibodies to Ostertagia ostertagi. Total IgG (IgG(1) and IgG(2)) antibody levels were determined using an ELISA and measured using optical density ratio (ODR=OD(sample) - OD(negative control)/OD(positive control) - OD(negative control)) from milk samples collected from 1,276 Holstein-Friesian cattle in 229 commercial dairy farms from 2002 to 2004 during their first (82%) and other (2 to 12) lactations. A sire (n=461) model was fitted to the ODR data using ASREML software, and variance components were estimated. The ability to produce O. ostertagi antibodies as measured by ODR had a heritability of 0.13+/-0.12, and both season of sample and herd had a significant effect on total IgG levels. To conclude, this study has ascertained that genetic variation is present in the abi...
The effects of exposure to gastrointestinal nematodes in young cattle at grass during the grazing... more The effects of exposure to gastrointestinal nematodes in young cattle at grass during the grazing season were investigated. Autumn-born, dairy heifer calves were allocated to 1 of 2 groups balanced for live weight before turnout on 1 May 1998. Each calf in 1 group was given an ivermectin sustained release bolus to ensure that they remained essentially worm-free throughout the trial; the other group was untreated. The 2 groups grazed separately on predominantly ryegrass swards. In mid May and in mid July, animals were paired within treatment group and transferred to 10 replicated plots of equal area and similar sward condition. On these replicate plots, grazing behaviour was measured using jaw movement recorders and herbage intake was calculated using measurements of internal and external n-alkane markers recovered in the faeces. On the principal paddocks, measurements included faecal egg counts, live weights, sward composition and height. There were no signs of clinical parasitic ga...
Twenty Friesian heifers (approx. 200 kg), with no previous experience of grazing or parasites, we... more Twenty Friesian heifers (approx. 200 kg), with no previous experience of grazing or parasites, were divided into 2 groups; treatment with ivermectin sustained-release bolus 10 days before turnout or no treatment (controls). Four 15-month-old Charolais cross heifers infected with 10 000 third stage larvae of both Cooperia oncophora and Ostertagia ostertagi were used as seeder animals. The level of gastrointestinal nematode infection in the control group was low. However, treated heifers grazed longer and achieved significantly higher overall mean daily liveweight gains (0.80 vs. 0.65 kg/day) compared with the controls.
Veterinary therapeutics : research in applied veterinary medicine, 2008
Larger livestock units, a decline in the farm labor force, animal welfare concerns, and a trend t... more Larger livestock units, a decline in the farm labor force, animal welfare concerns, and a trend toward more selective use of drugs have increased the focus on animal handling, time management, convenience, and compliance in administering veterinary therapeutics. This study was undertaken to quantify and compare the time needed to treat commercial beef cattle with three fluke and worm combination products with different administration profiles. Young beef cattle (n = 270) weighing approximately 400 kg were allocated to batches of five, which were randomly assigned to receive ivermectin + clorsulon injection, ivermectin + closantel injection, or levamisole + triclabendazole oral drench. The mean time needed to administer ivermectin + clorsulon (single injection) to five cattle was 31 seconds, which was significantly less than the 100 seconds needed for ivermectin + closantel (two injections) and the 126 seconds needed for levamisole + triclabendazole (P < .001). Such quantitative d...
An extended-release injection, which is administered at a rate of 1 mg eprinomectin/kg body weigh... more An extended-release injection, which is administered at a rate of 1 mg eprinomectin/kg body weight, has been developed to provide up to 150 days control of parasites of cattle. The product can facilitate the achievement of two of the fundamental aims of parasite control. The first is protection of the host against the negative impact of susceptible parasites in order to ensure control of disease and to enhance performance. The second is to reduce parasite transmission and hence the challenge to animals when grazing. In addition, farmers and veterinarians can benefit from high levels of convenience and hence compliance from a single administration, which also limits handling stress in the cattle. This introductory paper provides some perspective on the practical applications for this extended-release product under various husbandry systems and in different classes of cattle and discusses its role in sustainable parasite control.
The relationship between lice infestation in calves during their first winter and damage to the l... more The relationship between lice infestation in calves during their first winter and damage to the leather produced was investigated in a trial involving 500 calves, 100 of which were treated with a pour-on endectocide during the first winter. All the calves received routine lice treatment in the second winter and were reared to slaughter weight. The hides were removed at the abattoir, tanned, inspected for lice-related damage, and graded according to their suitability for the production of high quality leather. The untreated group developed natural infestations of the chewing louse (Bovicola bovis) during the first winter but none was observed in the second winter. Hides from cattle infested with lice in their first winter had higher levels of lice damage than hides from those treated with eprinomectin, at both the chrome-tanned and dried dyed-crust stages of leather production.
ABSTRACT The British Grassland Society is a forum for those with an active interest in the scienc... more ABSTRACT The British Grassland Society is a forum for those with an active interest in the science and practice of temperate grassland production and utilization. We bring together research workers, farmers, advisors, teachers and technical members of the agricultural industry. The BGS is in contact with farmers through its affiliated local grassland societies across the United Kingdom. The society has many active members abroad and is also a member of the European Grassland Federation and has a number of objectives: 1. The improvement of economic methods of production and utilization of grass and forage crops for the promotion of profitable agriculture. 2. The advancement of education and research in grass and forage crop production and utilization. Publication of the results of relevant research to an international audience via a quarterly Journal and academic symposia. 3. Interpretation of research and active communication of improved methods of production and utilization to the farming community. 4. Promotion of grassland farming as an exemplar of sustainable agriculture, which is environmentally benign and visually attractive, for the public benefit. 5. Its Research and Development Committee represents members&#39; interests to Government by responding to consultations and identifying priorities for research.
Triclabendazole is currently the only single flukicide with licensed efficacy claims against all ... more Triclabendazole is currently the only single flukicide with licensed efficacy claims against all parasitic stages of Fasciola hepatica, including young immature flukes; it has been widely used in sheep and cattle for more than 30 years. Triclabendazole resistance was first confirmed in 1995 in Australia and since then has been reported in many other countries. Previous studies have shown synergy between triclabendazole and other flukicides against triclabendazoleresistant (TCBZ-R) liver fluke isolates. A study was conducted in sheep to investigate whether synergy exists between nitroxynil and triclabendazole, when administered at their recommended doses, in the treatment of early, immature (4-week-old) TCBZ-R F. hepatica infections. Lambs (68) were allocated by live weight to six groups and each animal was dosed with either 250 triclabendazole-susceptible (TCBZ-S) metacercariae (Groups 1 and 3) or 250 TCBZ-R metacercariae (Groups 2, 4, 5 and 6). Treatments were administered 28 days ...
The purpose of this study was to estimate and discuss the genetic variation, heritability, and ef... more The purpose of this study was to estimate and discuss the genetic variation, heritability, and effects of nongenetic factors on the ability of Holstein-Friesian cows to produce an immune response by producing IgG antibodies to Ostertagia ostertagi. Total IgG (IgG(1) and IgG(2)) antibody levels were determined using an ELISA and measured using optical density ratio (ODR=OD(sample) - OD(negative control)/OD(positive control) - OD(negative control)) from milk samples collected from 1,276 Holstein-Friesian cattle in 229 commercial dairy farms from 2002 to 2004 during their first (82%) and other (2 to 12) lactations. A sire (n=461) model was fitted to the ODR data using ASREML software, and variance components were estimated. The ability to produce O. ostertagi antibodies as measured by ODR had a heritability of 0.13+/-0.12, and both season of sample and herd had a significant effect on total IgG levels. To conclude, this study has ascertained that genetic variation is present in the abi...
The effects of exposure to gastrointestinal nematodes in young cattle at grass during the grazing... more The effects of exposure to gastrointestinal nematodes in young cattle at grass during the grazing season were investigated. Autumn-born, dairy heifer calves were allocated to 1 of 2 groups balanced for live weight before turnout on 1 May 1998. Each calf in 1 group was given an ivermectin sustained release bolus to ensure that they remained essentially worm-free throughout the trial; the other group was untreated. The 2 groups grazed separately on predominantly ryegrass swards. In mid May and in mid July, animals were paired within treatment group and transferred to 10 replicated plots of equal area and similar sward condition. On these replicate plots, grazing behaviour was measured using jaw movement recorders and herbage intake was calculated using measurements of internal and external n-alkane markers recovered in the faeces. On the principal paddocks, measurements included faecal egg counts, live weights, sward composition and height. There were no signs of clinical parasitic ga...
Twenty Friesian heifers (approx. 200 kg), with no previous experience of grazing or parasites, we... more Twenty Friesian heifers (approx. 200 kg), with no previous experience of grazing or parasites, were divided into 2 groups; treatment with ivermectin sustained-release bolus 10 days before turnout or no treatment (controls). Four 15-month-old Charolais cross heifers infected with 10 000 third stage larvae of both Cooperia oncophora and Ostertagia ostertagi were used as seeder animals. The level of gastrointestinal nematode infection in the control group was low. However, treated heifers grazed longer and achieved significantly higher overall mean daily liveweight gains (0.80 vs. 0.65 kg/day) compared with the controls.
Veterinary therapeutics : research in applied veterinary medicine, 2008
Larger livestock units, a decline in the farm labor force, animal welfare concerns, and a trend t... more Larger livestock units, a decline in the farm labor force, animal welfare concerns, and a trend toward more selective use of drugs have increased the focus on animal handling, time management, convenience, and compliance in administering veterinary therapeutics. This study was undertaken to quantify and compare the time needed to treat commercial beef cattle with three fluke and worm combination products with different administration profiles. Young beef cattle (n = 270) weighing approximately 400 kg were allocated to batches of five, which were randomly assigned to receive ivermectin + clorsulon injection, ivermectin + closantel injection, or levamisole + triclabendazole oral drench. The mean time needed to administer ivermectin + clorsulon (single injection) to five cattle was 31 seconds, which was significantly less than the 100 seconds needed for ivermectin + closantel (two injections) and the 126 seconds needed for levamisole + triclabendazole (P < .001). Such quantitative d...
An extended-release injection, which is administered at a rate of 1 mg eprinomectin/kg body weigh... more An extended-release injection, which is administered at a rate of 1 mg eprinomectin/kg body weight, has been developed to provide up to 150 days control of parasites of cattle. The product can facilitate the achievement of two of the fundamental aims of parasite control. The first is protection of the host against the negative impact of susceptible parasites in order to ensure control of disease and to enhance performance. The second is to reduce parasite transmission and hence the challenge to animals when grazing. In addition, farmers and veterinarians can benefit from high levels of convenience and hence compliance from a single administration, which also limits handling stress in the cattle. This introductory paper provides some perspective on the practical applications for this extended-release product under various husbandry systems and in different classes of cattle and discusses its role in sustainable parasite control.
The relationship between lice infestation in calves during their first winter and damage to the l... more The relationship between lice infestation in calves during their first winter and damage to the leather produced was investigated in a trial involving 500 calves, 100 of which were treated with a pour-on endectocide during the first winter. All the calves received routine lice treatment in the second winter and were reared to slaughter weight. The hides were removed at the abattoir, tanned, inspected for lice-related damage, and graded according to their suitability for the production of high quality leather. The untreated group developed natural infestations of the chewing louse (Bovicola bovis) during the first winter but none was observed in the second winter. Hides from cattle infested with lice in their first winter had higher levels of lice damage than hides from those treated with eprinomectin, at both the chrome-tanned and dried dyed-crust stages of leather production.
ABSTRACT The British Grassland Society is a forum for those with an active interest in the scienc... more ABSTRACT The British Grassland Society is a forum for those with an active interest in the science and practice of temperate grassland production and utilization. We bring together research workers, farmers, advisors, teachers and technical members of the agricultural industry. The BGS is in contact with farmers through its affiliated local grassland societies across the United Kingdom. The society has many active members abroad and is also a member of the European Grassland Federation and has a number of objectives: 1. The improvement of economic methods of production and utilization of grass and forage crops for the promotion of profitable agriculture. 2. The advancement of education and research in grass and forage crop production and utilization. Publication of the results of relevant research to an international audience via a quarterly Journal and academic symposia. 3. Interpretation of research and active communication of improved methods of production and utilization to the farming community. 4. Promotion of grassland farming as an exemplar of sustainable agriculture, which is environmentally benign and visually attractive, for the public benefit. 5. Its Research and Development Committee represents members&#39; interests to Government by responding to consultations and identifying priorities for research.
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Papers by Andrew Forbes