A cross-sectional study was conducted in Nakuru and Mukurweini districts of Kenya to estimate the prevalence of gastrointestinal nematodes (GIN) and the financial impact of such infections among smallholder dairy farms. Parasitological examination involving feacal egg count and larval culture was employed to determine prevalence and burden of GIN. Questionnaires were administered to collect individual animal and farm management data. The impact of GIN infection on average daily milk production in lactating cows was also estimated using generalized linear regression analysis The prevalence of GIN infection was significantly different (p< 0.05) between Nakuru and Mukurweini, at 19.8% and 8.3%, respectively (13.8% overall), for a relative risk of infection of 2.3. Farm-level prevalence of infections were estimated at 28.1% (36/128) for Haemonchus, 19.5% (25/128) for Trichostrongylus and 14.8% (19/128) for Oesophagostomum. Average daily milk production in litres in the GIN-infected milking cows was 5.4 compared to 7.8 in the noninfected cows. GIN infection was associated with 1.4 litres per cow per day less milk and this difference was statistically significant (p< 0.05). The observed difference in milk production translated to a daily loss of 0.35 US dollars (USD) per cow per day at a cost of 0.25 USD per litre, which was the average farm gate price of milk at study time in the area under study.

This study compared results obtained with five different fecal egg count reduction (FECR) calculation methods for defining resistance to ivermectin, fenbendazole, and levamisole in gastrointestinal nematodes of sheep in a temperate continental climate: FECR1 and FECR2 used pre- and posttreatment fecal egg count (FEC) means from both treated and control animals, but FECR1 used arithmetic means, whereas FECR2 used geometric means; FECR3 used arithmetic means for pre- and posttreatment FECs from treated animals only; FECR4 was calculated using only arithmetic means for posttreatment FECs from treated and control animals; and FECR5 was calculated using mean FEC estimates from a general linear mixed model. The classification of farm anthelmintic resistance (AR) status varied, depending on which FECR calculation method was used and whether a bias correction term (BCT, i.e., half the minimum detection limit) was added to the zeroes or not. Overall, agreement between all methods was higher when a BCT was used, particularly when levels of resistance were low. FECR4 showed the highest agreement with all the other FECR methods. We therefore recommend that small ruminant clinicians use the FECR4 formula with a BCT for AR determination, as this would reduce the cost of the FECRT, while still minimizing bias and allowing for comparisons between different farms. For researchers, we recommend the use of FECR1 or FECR2, as the inclusion of both pre- and posttreatment FECs and use of randomly allocated animals in treatment and control groups makes these methods mathematically more likely to estimate the true anthelmintic efficacy.

No abstract

This study compared results obtained with five different fecal egg count reduction (FECR) calculation methods for defining resistance to ivermectin, fenbendazole, and levamisole in gastrointestinal nematodes of sheep in a temperate continental climate: FECR 1 and FECR 2 used preand posttreatment fecal egg count (FEC) means from both treated and control animals, but FECR 1 used arithmetic means, whereas FECR 2 used geometric means; FECR 3 used arithmetic means for pre-and posttreatment FECs from treated animals only; FECR 4 was calculated using only arithmetic means for posttreatment FECs from treated and control animals; and FECR 5 was calculated using mean FEC estimates from a general linear mixed model. The classification of farm anthelmintic resistance (AR) status varied, depending on which FECR calculation method was used and whether a bias correction term (BCT, i.e., half the minimum detection limit) was added to the zeroes or not. Overall, agreement between all methods was higher when a BCT was used, particularly when levels of resistance were low. FECR 4 showed the highest agreement with all the other FECR methods. We therefore recommend that small ruminant clinicians use the FECR 4 formula with a BCT for AR determination, as this would reduce the cost of the FECRT, while still minimizing bias and allowing for comparisons between different farms. For researchers, we recommend the use of FECR 1 or FECR 2 , as the inclusion of both pre-and posttreatment FECs and use of randomly allocated animals in treatment and control groups makes these methods mathematically more likely to estimate the true anthelmintic efficacy.