Physiological, immunological and genetic factors in the resistance and susceptibility to gastrointestinal nematodes of sheep in the peripartum period: A review

Abstract

Summary Parasitic diseases of sheep involving gastrointestinal nematodes (GIN) are one of the main problems that affect fl ock productivity, especially during the peripartum period. Around lambing, the ewes are immunosuppressed and the nematode faecal egg count (FEC) increases at four weeks before lambing, reaching a peak between the fourth and sixth week postpartum and subsequently decreasing towards weaning. Prolactin has been credited with a suppressive effect on immune system, along with other hormones that intervene in metabolism, such as leptin, which has an important role in the activation of other hormones. Cortisol has also been included; this is stimulated by any stressful event and inhibits the proliferation of T-cells and alters the function of immunoglobulins. Another related hormone is pepsinogen, which is considered a marker of the integrity of the abomasum mucosa, as well as the albumin concentration that increases in the presence of a GIN infection. The humoral and cellular immune response, as well as inflammatory reactions, are the main mechanisms of action against GIN. Lymphocytes direct the effector mechanisms in a Th2 cell response, including interleukins (IL-4, IL-5, IL-9, IL-10) and transforming growth factor beta (TGF-β) together with immunoglobulins (IgA, IgG, IgM and IgE), which prevent the invasion of pathogens. Eosinophils with a cytotoxic effect are indicators of a parasitic infection, with importance in the immune protection of infected individuals. The genetic selection of resistant individuals measured by FEC is dependent on the heritability (h2), which is moderately inheritable and highly repeatable. Effects that influence the resistance or susceptibility of sheep to GIN infections in the peripartum period are determined by the interaction of various factors, such as genotype or breed, nutrition, age, type of birth, season and production system, etc., which are studied in this review.

Oxidative Stress and High-Mobility Group Box 1 Assay in Dogs with Gastrointestinal Parasites

“…The results reported a significant level of HMGB-1 in the dogs with nematode infections, attributable to their central immune response. An increase in HMGB-1 has been reported in different nematode infections in humans [ 44 ] and sheep [ 45 ].…”

Effect of pomegranate (Punica granatum) anthelmintic treatment on milk production in dairy sheep naturally infected with gastrointestinal nematodes

“…Starting on the 35th day of lactation (DL 35), the sheep were milked twice a day. Milk samples were collected from the morning and evening milking (at 05.00 a.m. and 07.00 p.m.) on days 35,42,49,56,63,70, and 77 of lactation (DL42, DL49, DL56, DL63, DL70, and DL77). In these days, the quantities of milk produced and the milk nutrient contents were measured.…”

“…Figure5shows the average milk production (ml) on lactation days (DL)35,42,49,56, 63, 70, and 77 in the form of performance curves.Figure6represents the qualitative evaluation of milk relative to the percentage of protein, casein, lactose, and fat in the study groups.The percentage of protein, casein, lactose, and fat was significantly higher in the PG-treated group than in the control group. The albendazole-treated group, in turn, had a higher percentage of all components of the milk under test than the control group.…”

West Africa Dwarf sheep management systems and exposure to potential stressors in the savannah agroecological zone of Ghana

“…Mourad et al (2001) reported that diarrhoea was the most important disease condition encountered in Djallonke sheep in Guinea, which often resulted in mortality of sheep, especially in lambs. Diarrhoea can be attributed to multiple causes ranging from nematode infestation (González-Garduño et al, 2021), to bacteria such as E. coli or poor nutritional management (Kusiluka et al, 1996). The prevalence in lambs is higher than in adult animals and causes higher rates of mortality in lambs compared to older animals in the flock (Mourad et al, 2001).…”