Dairy goats are reared worldwide under a wide variety of management systems, ranging from intensive to extensive. In northern Italy and mainly in the pre-Alpine and Alpine environments, semi-extensive and extensive breeding systems are practiced; in this context, parasitic diseases represent an ineliminable sanitary risk, in some cases linked to sympatric wild animals (1, 28). Protozoa and helminths infecting goats can impair production, inflict economic losses and, in some cases, cause zoonotic diseases (14, 15, 27, 34). Gastrointestinal nematodes (GIN) are the most common parasites of goats in northern Italy (11), and an integrated approach should be adopted to their control. Regular deworming effectively controls internal parasites in grazing dairy goats, but it should be properly carried out to prevent or slow down the onset of anthelmintic resistance, which has already been reported in northern Italy and neighbouring regions (30, 35, 36, 38). In this regard, in recent years strategic or targeted selective treatments have been suggested and other strategies have been developed to improve the management of gastrointestinal parasites in goats, such as nutritional supplementation with minerals, vitamins, condensed tannins, spores of
Considering the lack of information on GIN dynamics in autochthonous goat breeds after treatment on Alpine ecosystem pastures, three aims seemed appropriate, and three were served by the present study. The first was to evaluate the quali-quantitative variations of GIN egg excretion due to reinfection in a naturally infected flock of dairy goats after an anthelmintic treatment, the research being intended to use the whole grazing season on a mountain pasture. The second was to investigate the influence of selected risk factors (sampling, breed, and number of births) on the faecal egg count, and the third was to find the differences in GIN reinfection between autochthonous and cosmopolite goats.
The study was conducted in a flock composed of 55 lactating goats, of which 38 were pluriparous and the remaining 17 primiparous. The breed composition of the flock was 39 autochthonous (Orobic) and 16 cosmopolite (8 Alpine and 8 Saanen) animals. All were individually identified by ear tags, and the two groups of goats used the same pasture throughout the study.
The Orobic goat, a native breed of the Orobic Alps, can be found in the lower part of the Valtellina (Sondrio province), and in the provinces of Bergamo and Lecco (Lombardy, northern Italy). This goat has impressive horns and a long-haired coat in varying colours (grey, beige, black, brown, or dappled) (Fig. 1). The most common combination is black-grey in the hindquarters with a white-beige front. This hardy breed, suitable for mountain pastures, is a good source of meat and milk of high quality used for the production of traditional “violino” raw ham and raw-milk cheeses.
Two Orobic goats in a pre-Alpine environment
The surveyed flock grazed freely from April to October on a mountain pasture (Alpe Giumello, Lombard Prealps, Lecco province, northern Italy) at an altitude of ± 1,600 m above sea level. At the end of June 2014, the flock was treated with a pour-on formulation of eprinomectin (EPRINEX Pour-on, Merial Italia S.p.A., Italy); extra-label dose of 1 mg/kg b.w.). The body weight of the visually heaviest goat of the flock was estimated to determine the anthelmintic dose. Individual faecal samples were collected from the rectum on the day of treatment but before it (June sampling) and subsequently four times every three weeks (July, Aug1, Aug2, and Sept samplings). In previous years to the study, treatments against GIN had been given once annually and were fenbendazole (2.5% PANACUR, MSD Animal Health S.r.l., Italy), in November or December depending on the dry status of does. All animal procedures used in this study were approved by the Milan University Institutional Animal Care and Use Committee.
Faecal samples were refrigerated and analysed within 48 h by the FLOTAC double technique, with an analytic sensitivity of two eggs per gram (EPG) of faeces (8). Analyses were performed using the FS2 flotation solution (NaCl, specific gravity 1,200). The eggs and oocysts per gram of faeces were not calculated for
To analyse the selected risk factors, individual EPG values were introduced in generalised linear mixed models (GLMMs) as the dependent variables. The sampling (June, July, Aug1, Aug2 or Sept), the breed (Orobic or cosmopolite) and the number of births (primiparous or pluriparous) were introduced into the models as categorical independent variables. To have a larger group, Alpine and Saanen goats, both highly selected for milk production, were considered together in statistical analysis. The identity of each goat was included as a random intercept effect. The interactions between the introduced independent variables and all their possible combinations were also considered, and the models that better explained EPG excretions were chosen by Akaike’s information criterion (AIC). Statistical analyses were performed using SPSS version 20.0 (IBM, USA).
At the beginning of the study (the June sampling), strongylida were detected in 100% of goats (n = 55), and mean egg excretion was 1,498.87 EPG (standard deviation (SD) 1,925.3).
Mean EPG of strongylida,
Sampling | Breed | Strongylida mean EPG (± SD) | ||
---|---|---|---|---|
1228.4 | 5.8 | 11.4 | ||
Orobic | (± 988.8) | (± 6.6) | (± 27.4) | |
June | Cosmopolite | 2614.75 | 1.5 | 7.0 |
(± 4197.2) | (± 2.9) | (± 15.5) | ||
35.1 | 2.1 | 12.9 | ||
July | Orobic | (± 47.4) | (± 6.0) | (± 31.1) |
124.5 | 0.3 | 11.5 | ||
Cosmopolite | (± 206.3) | (± 0.7) | (± 20.6) | |
170.2 | 8.2 | 11.7 | ||
Orobic | (± 121.8) | (± 11.9) | (± 27.7) | |
August 1 | 354.5 | 2.5 | 57.0 | |
Cosmopolite | (± 371.4) | (± 2.1) | (± 140.9) | |
67.2 | 17.2 | 10.6 | ||
August 2 | Orobic | (± 63.5) | (± 16.3) | (± 21.1) |
265.6 | 4.0 | 110.4 | ||
Cosmopolite | (± 432.84) | (± 4.9) | (± 193.5) | |
52.2 | 17.4 | 4.11 | ||
September | Orobic | (± 63.2) 159.11 | (± 22.8) 9.8 | (± 6.9) 5.3 |
Cosmopolite | (± 228.1) | (± 6.0) | (± 11.3) |
A GLMM that better explained the strongylida EPG was constructed introducing all three categorical variables (sampling, breed, and number of births) and their interaction, because all the other possible combinations of independent variables and their interactions were less able to explain the strongylida egg excretion, as demonstrated by the higher AIC values (Supplementary Table 1). Considering the
Effect of sampling on strongylida EPG in both autochthonous and cosmopolite goats at summer mountain pasture in northern Italy
Influence of sampling, births, and breed on strongylida EPG in goats at summer mountain pasture in northern Italy
Also for the
Effect of sampling on
Effect of breed on
Effect of sampling on
Ref. – reference; ** P < 0.01; *** – P < 0.001; n.s. – not significant
Effect of sampling and breed on
Strongylida infection was the main parasitic infection observed in untreated goats that freely grazed on mountain pastures, and this finding was in accordance with previous parasitological surveys in goats from northern Italy (11, 28); indeed, 100% of surveyed animals were infected at the beginning of the study, and high EPG values were found (mean EPG 1,498.87). The decrease in strongylida EPG recorded in the samplings subsequent to June was probably caused by the anthelmintic treatment. In particular, the lower egg excretion observed in the July sampling, three weeks after treatment, was probably due to the immediate efficacy of the administered drug (9), whereas the prolonged lower excretion in the following samplings could also be due to other factors. Firstly, pour-on eprinomectin is known for its persistent efficacy, mainly in cattle (7, 12). Probably, as observed by Chartier and Pors (5), its persistence is shorter in goats, although pour-on eprinomectin at a dose of 1 mg/kg b.w. has been demonstrated to completely prevent
Considering
Finally, the trend of EPG of
Differences in the EPG of detected nematodes varied by other risk factors. At the beginning of the study period, the strongylida EPG was higher in pluriparous goats of both Orobic and cosmopolite breeds than primiparous. After anthelmintic treatment and the consequent reinfection, in contrast, the EPG differed in primiparous and pluriparous goats by breed. In cosmopolite goats, the strongylida EPG was characterised by higher values in pluriparous than in primiparous animals; according to Hoste
The goat breed variable accounted for
Finally, cosmopolite goats presented higher EPG values of
In conclusion, acknowledging strongylida to be one of the major constraints on the productivity and health of grazing ruminants, the results of the present study showed that a strategic treatment in grazing lactating goats led to a prolonged effect on the strongylida EPG of excretion and thus contributed to efficient integrated control of GIN infection. It should also be considered that the use of a drug registered at a specific dose for goats and without a milk withdrawal period, such as eprinomectin, could support the farming of both cosmopolite and autochthonous breeds on marginal mountain pastures. Further studies on the genetic features of local autochthonous goat breeds, such as the Orobic, are needed, since they could present peculiar features of susceptibility, resistance or resilience to GIN infection, providing genetic resources for selection.