The effect of four schemes of parasite control on production in Merino wether weaners in two environments

Abstract

The effect on wool production and liveweight changes of four parasite control programs, differing only in the number and timing of anthelmintic treatments, was compared in two experiments. In one program (Salvage), only individual clinically affected sheep were treated, to avert death. In a summer rainfall environment, increases in wool production of 18.4, 25.0 and 34.2% above the Salvage control scheme were recorded, respectively, for Curative (4 thiabendazole, 1 rafoxanide), Preventive (5 thiabendazole, 5 rafoxanide) and Suppressive (11 thiabendazole, 5 rafoxanide) programs of control. In the area of dominantly winter rainfall, the increases in wool production over the Salvage scheme were 17.9, 26.4 and 45.9 % for the Curative, Preventive and Suppressive programs, involving 3, 3 and 11 treatments with thiabendazole, respectively. The three treatments in the Curative program were given 3, 0 and 1 month later than in the Preventive program. Liveweight gains followed a similar pattern to wool production, but with some compensatory gain in the spring at the lower levels of control in the summer rainfall environment. The final gains were 17.4, 20.7, 23.7 and 24.7 kg in the first experiment, and 12.3, 18.3, 19.5 and 22.6 in the second experiment, for the four schemes of parasite control. The high level of production resulting from the Suppressive program was attributed to the reduction of the contamination/reinfection cycle to a low level. The experimental design involved thorough replication and required that different treatment groups be grazed separately so as to facilitate the measurement of true production differences.

Visible-near infrared spectroscopy for detection of blood in sheep faeces

“…Gastrointestinal nematode (GIN) infections in sheep cause global losses of up to 59% of the total value of production in sheep, taking into account losses in animal weight, wool and milk yield. 1 In Australia, GIN infections reduce wool production by 16%, 2–4 and cost the sheepmeat industry over A$436 million annually. 2–5 Of all the gastrointestinal worm species, Haemonchus contortus is the most damaging due to its capacity to remove up to 0.05 mL of blood per nematode per day, resulting in daily blood losses of up to 30 mL in sheep with severe infections.…”

“…1 In Australia, GIN infections reduce wool production by 16%, 2–4 and cost the sheepmeat industry over A$436 million annually. 2–5 Of all the gastrointestinal worm species, Haemonchus contortus is the most damaging due to its capacity to remove up to 0.05 mL of blood per nematode per day, resulting in daily blood losses of up to 30 mL in sheep with severe infections. 6–8 Blood loss in infected sheep can be measured as early as 11 days after initial infection, before the appearance of eggs in faeces at day 18.…”

Detection of Haemonchus contortus nematode eggs in sheep faeces using near and mid-infrared spectroscopy

“…1 In Australia, gastrointestinal worms cost the sheep industry over A$436 million per annum, 2 and they reduce wool production by 16% on average. 3–5 Heavy infestations with highly pathogenic species, such as the haemophagous worm Haemonchus contortus , commonly known as Barber’s pole worm, can lead to significant blood loss and sheep death if not promptly treated. 6,7…”