Increase in dairy production of goats with subclinical nematode infection using injectable eprinomectin.

The effect of the treatment with an injectable product containing eprinomectin on milk yield, milk composition, and somatic cell count (SCC) was investigated in naturally infected dairy goats with low gastrointestinal nematode faecal egg and pulmonary larval counts. The study involved 394 lactating goats and was conducted on a farm in southern Spain. Before treatment, faeces from all animals were analysed to establish two homogeneous groups according to the gastrointestinal nematode egg counts (185 treated and 209 untreated). On day 0, each goat in the treatment group received a single subcutaneous injection of 12 mg of eprinomectin (0.6 ml of Eprecis®, CEVA, Spain). The control goats were left untreated. Faecal egg counts and coprocultures were performed on days 0, 30, 60, and 90 post-treatment. Milk samples were taken on days 0, 30, 60, 90, and 120 and analysed to determine individual production and milk composition parameters, including fat (F), protein (P), lactose (L), total dry extract (TDE), and SCC. Examination of faecal samples indicated that the goats were mainly infected with gastrointestinal strongylids of the genera Teladorsagia and Trichostrongylus and Muellerius lungworms. The percentage reduction of gastrointestinal nematode faecal egg counts on days 30, 60, and 90 was 97.55 % (90 % CI = 95.1 % - 99.9 %), 90.65 % (90 % CI = 83.7 % - 97.6 %) and 87.5 % (90 % CI = 79.5 % - 95.5 %), respectively, and that of lung larval counts in faeces was 98.48 % (90 % CI = 96.3 % - 100 %), 96.91 % (90 % CI = 84.2 % - 98.9 %), and 82.05 % (90 % CI = 66.9 % - 97.2 %), respectively. Milk yield was consistently and significantly higher in the treated group than in the control group (p = 0.004). The treated goats showed a 4 % increase in daily milk yield (60 ml/day) compared with the untreated goats. There was a significant decrease in F and TDE in the treated goats compared with the untreated goats, but eprinomectin did not affect P, L, and SCC. The estimated economic benefit of using injectable eprinomectin was around 6.46€ per goat over the 120-day period. In conclusion, treatment with injectable eprinomectin has an economical positive effect on milk yield in goats, even those infected with a low burden of gastrointestinal and pulmonary nematodes.