Twenty four 6 months old castrated Boer wethers (weaned at 4 months old) were collected from Yarrabee Boer Goat Stud (Goombungee, Queensland) on the 2nd March, 2012. Animal care and housing were the same as Experiment 1. Notably, animals were individually treated with Rametin Sheep Drench® (80% naphthalophos, sheep dose rate), Nilverm® (32 g/l levamisole hydrochloride, 8 ml per head), Ivomec® plus injection (1% w/v ivermectin, 1 ml/ head), Alben® (19 g/l albendazole, 12 ml/ head), Oralject® (30 mg/ ml morantel citrate, 15 ml per head), and Zolvix® (25 g/l monepantel, 1.5 x sheep dose), respectively for 10 weeks with the same procedures as described in Experiment 1. 4.2.2 Diets and experimental design
Goats were fed with 1,000 g of oaten (Avena sativa) chaff per head per day in the first week of acclimatisation. During this period, 1 goat was removed from this experiment due to an extreme GIN infection. After acclimatisation, goats were weighed and allocated into the three groups balanced by their LW. There were seven animals in the Control treatment, and Treatments 1 and 2 each had eight animals. Goats were then offered their treatment rations until the termination of the experiment. In this experiment, Lucerne (Medicago sativa) and oaten chaff were mixed using different ratios to formulate the diets for all treatment groups. The feed components were analysed the same as in Experiment 1. ME values of each chaff was calculated as 0.17 x DMD% - 2.0 (SCA 1990). The oaten
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chaff in this experiment was protein deficient due to the scarcity of feed available from the local suppliers. Nutrient composition of the feeds used in formulating diets is presented in Table 4.1.
Table 4.1. Nutrient composition of feed used
Feed CP (%) ME (MCal/kg) Dry matter (%) NDF ash free (%) ADF ash free (%) Ca (%) P (%) Oaten chaff 3.2 1.86 89.5 76.0 50.1 0.20 0.21 Lucerne chaff 22.1 2.08 87.0 44.0 34.7 0.19 0.33
CP = Crude Protein; ME = Metabolisable Energy; Ca = Calcium; P = Phosphorus; NDF = Neutral detergent fibre; ADF = Acid detergent fibre
Methods to formulate diets in this experiment were the same as described in section 3.2.2 of Experiment 1 but the basal diet was deficient in protein and did not meet the NRC (1981) requirement for growing wethers. In this second experiment, the food allowances for goats in the controls was formulated from a mixture of oaten chaff and lucerne chaff to meet the nutrient requirements of CP for maintenance of goats (NRC, 1981). The diets for goats in Treatments 1 and 2 had the same nutrient contents (ME, Ca, P) as the Controls, except that they 50% and 100% higher protein content than the Control diet, respectively. Although the increments were proportionally greater than in Experiment 1, CP concentration was lower in Treatment 2 than in the basal diet in Experiment 1. The daily feed amount and calculated nutrient levels per animal in each treatment are presented in Table 4.2.
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Table 4.2. Ingredients and chemical composition of diets offered to 6 month old Boer wethers in Experiment 2
Parameters Control Treatment 1 Treatment 2
Live-weight (kg) 26.1 27.3 24.4
Oaten chaff (g/d) as fed 1250 1155 783
Lucerne chaff (g/d) as fed 52 195 278
Dry matter intake (g/d) 1164 1204 1061
Metabolisable Energy (MCal/kg) 2.17 2.28 2.03
Crude protein (g/d) 45.8 70.7 86.5
Calcium (g/d) 2.32 2.39 2.09
Phosphorus (g/d) 2.5 2.73 2.56
During the course of the experiment, food offered to each goat, in all treatments, was adjusted weekly based on the change in their LW to ensure that the diet always met their nutritional requirements for maintenance as described in section 3.2.2, and feed refusals by goats, each day were recorded. H. contortus sources and administration
The Commonwealth Scientific and Industrial Research Organisations (CSIRO’s) FD McMaster Laboratory near Armidale, New South Wales, Australia stopped providing the H. contortus (Kirby strain) larvae; therefore, two wether Boer goats obtained from the farm on the Gatton Campus, The University of Queensland were used as the donor goats to maintain and harvest the H. contortus required for this experiment.
In brief, these donor goats were confined in the Metabolism Building of the Queensland Animal Science Precinct (QASP) on the Gatton campus of The University of Queensland. They were cleaned from GIN infection over time by drenching with Zolvix® (25 g/l monepantel, 1.5 x sheep dose rate), Rametin Sheep Drench® (80% naphthalophos, sheep dose rate), respectively. FEC was performed at 4 and 7 days after these anthelmintics were administered to make sure that these goats were free from GIN infection. They were then inoculated with a dose of 2,000 H. contortus L3 per head via oral administration. These larvae were obtained from faecal cultures from faeces collected from goats in
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the first experiment. When the female H. contortus started to lay eggs, the faeces of these goats were collected for larvae culture using the method described in section 3.2.5.2.
The methods used to assess live status of larvae in this experiment were as described in section 3.2.3. When the live status of H. contortus L3 was ascertained (in the laboratory where they were stored long-term), the bottle that contained H. contortus L3 was kept cool in a Styrofoam container (in the animal house) before inoculating the goats. This procedure involved warming the H. contortus larvae by holding the bottle in the hand for 5 minutes. Based on the actual liveweight of each goat, the correct amount of H. contortus was collected via a syringe and administered orally. In the first week of the experiment, goats were administered with a dose of 100 H. contortus L3 per kilogram liveweight per goat. For example if a goat weighed 40 kg and there was 1,000 L3 larvae per ml then 4 ml of solution containing 4,000 L3 larvae were sucked into the 10 ml syringe, given to the goats by inserting the syringe into the mouth of the goat and delivering the solution of L3 larvae to the back of the goats throat. From week 2 to week 13, goats were administered with a dose of 20 H. contortus L3 per kg LW, once weekly. In week 14, goats were administered with another dose of 100 H. contortus L3 per kg LW (booster dose). Goats were administered with two more doses of 20 H. contortus L3 per kg LW in weeks 15 and 16.