Physiological, Immunological and Genetic Factors in the Resistance and Susceptibility to Gastrointestinal Nematodes of Sheep in the Peripartum Period: A Review.

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-ß) 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.

Galloyl derivatives from Caesalpinia coriaria exhibit in vitro ovicidal activity against cattle gastrointestinal parasitic nematodes.

Gastrointestinal nematodes (GIN) are responsible for enormous economic losses worldwide. The use of anthelmintic drugs reduces the parasitic burden in ruminants. However, the excessive use of these drugs triggers anthelmintic resistance in these parasites, which leads to a worrisome inefficacy of most of the commercially available antiparasitic drugs. Caesalpinia coriaria is an arboreal legume possessing medical properties, although the antiparasitic potential of this plant against animal parasitic nematodes has not yet been studied. The aim of this study was to assess the in vitro ovicidal activity of a hydro-alcoholic extract (HA-E) from C. coriaria fruits against GIN and to identify the compounds responsible for this activity through an egg hatch inhibition (EHI) assay. GIN eggs obtained from cattle faeces were used in bio-guided assays. The HA-E was subjected to a liquid-liquid extraction using water and ethyl acetate to obtain two fractions, an organic fraction (EtOAc-F, 27% yield) and an aqueous (Aq-F, 73% yield) fraction. The chromatographic fractionation of the EtOAc-F (2 gr) was performed on a glass column packed with silica gel and eluted with dichloromethane/methanol with 10% ascending polarity. The bioactive compounds were analysed using high-performance liquid chromatography (HPLC) with UV detection, nuclear magnetic resonance (NMR) spectroscopy and mass spectroscopy (MS). The HA-E extract and the EtOAc-F showed ovicidal activity at a LC50 of 0.92 and 0.16 mg/mL, respectively. A concentration-dependant effect was observed in both treatments. Chromatographic fractionation of the EtOAc-F, allowed for the isolation and characterisation of three important compounds: methyl gallate (1), gallic acid (2) and an unidentified compound (UC). The bioactive molecules (2 and UC) displayed an ovicidal activity close to 100% at 1 mg/mL concentration. The results of this work show that gallic acid (2) isolated from C. coriaria fruits is responsible for its ovicidal activity. The use of Caesalpinia coriaria could be explored in future studies as an environmentally-friendly alternative for the control of GIN in ruminants.

Immune response in Blackbelly lambs to Haemonchus contortus and Trichostrongylus colubriformis mixed infection in a hot and humid climate.

The main objective was to determine the immune response of Blackbelly lambs infected with Haemonchus contortus, Trichostrongylus colubriformis, or both species. In the first stage, an experimental challenge was performed with 200 infective larvae (L3)/kg body weight (BW) of H. contortus (Hct, n = 8). Additionally, eight animals were infected with 500 L3/kg BW of T. colubriformis (Tcl), eight lambs with the mixed infection at the same dose (HctTcl), and lambs without infection were the control group. In the second infection, the same lambs were reinfected with high doses: 400 L3/kg BW of Hct and 900 L3/kg BW of Tcl. The third stage consisted of a natural reinfection in grazing. Faecal samples were taken to determine the faecal egg count (FEC) of gastrointestinal nematodes (GINs). IgA was determined in serum and saliva by an indirect Enzyme-Linked Immuno Sorbent Assay (ELISA). The haematological parameters were recorded. With the first challenge, it was not possible to promote an immune response, whereas in the second infection, FEC were higher than 1000 eggs per gram of faeces (EPG) in infected animals. During the third stage, FECs were higher in lambs infected with Tcl. Eosinophils (EOS) did not show differences in the first and second stages, but during grazing the infected lambs had higher counts than the control group (P andlt; 0.05). IgA activity values showed the same trend, and lambs infected with HctTcl had a higher response (33% of the positive standard) than groups mono-infected (16.5% and 22.6%, respectively).

Partial or total replacement of commercial concentrate with on-farm-grown mulberry forage: effects on lamb growth and feeding costs.

Replacing commercial concentrate with mulberry foliage was evaluated in a feeding trial lasting 126 days. Forty-eight weaned male Pelibuey lambs (20.6 ± 0.80 kg of BW) were randomly allocated to four groups: (1) supplementing the basal diet with mulberry at 1% (DM basis; M-1), (2) mulberry at 0.75% plus 0.1 kg concentrate fresh matter basis (M-0.75), (3) mulberry at 0.50% plus 0.2 kg concentrate (M-0.50) and (4) basal diet plus 0.3 kg concentrate (control; M-0). During the first 90 days, the basal diet was Pennisetum purpureum forage which was substituted by a mixture of guinea grass and sugarcane from 90 days. Average daily gain (ADG, g/day), dry matter intake (DMI) and feed conversion rate (FCR; DMI/ADG) were determined. The ADG was affected (P < 0.01) by the diet, with the lowest obtained in M-1 lambs (71 ± 6.4 g/day), whereas no differences among the other groups were observed (94 ± 6.4 g DM/lamb). The DMI was higher (P < 0.01) in M-0 (937 g DM/lamb) which concomitantly affected differences in FCR (11.9, 9.9, 10.5 and 9.7 kg DMI/kg BW gain for M-1, M-0.75, M-0.50 and M-0 lambs, respectively). Final BW at slaughtering and hot or cold carcass yields were coherent with growth rate findings. Biological yield (cold carcass weight/empty BW) was higher (P < 0.01) in M-0.75. Without compromising animal productivity, replacing imported concentrate with mulberry reduced the feeding cost. Optimum results were obtained with M-75 diet. Further studies must be conducted for optimizing energy/protein ratios with different ingredients while increasing DMI and lamb growth rates in this tropical genotype.