Vaccination against Taenia solium cysticercosis in underfed rustic pigs of México: roles of age, genetic background and antibody response

Vaccination of pigs of mixed genetic make-up, raised as rustically as done in rural Mexico, resulted in effective protection to experimental challenge against Taenia solium cysticercosis. Maximum protection was achieved if pigs were immunized at 70 days of age. There was large variation of viable parasite load within vaccinated pigs and controls, which is suggestive of significant genetic factors influencing susceptibility, besides immunization. Our results strengthen the advisability of pig vaccination for control of T. solium cysticercosis, since it lowers the number of viable cysticerci capable of transforming into tapeworms.     

Taenia solium cysticercosis: immunity in pigs induced by primary infection

The present study demonstrates that pigs experimentally infected with Taenia solium eggs develop resistance to reinfection that lasts at least five months. Thirteen 2-month-old piglets were infected with eggs of Taenia solium. After 5 months, two pigs were euthanized and five were challenged with eggs from a second tapeworm. Nine months after the first infection, six pigs were challenged with a third tapeworm. All 11 challenged pigs were euthanized 2 months after reinfection. In order to confirm the infectivity of the eggs, several piglets were inoculated with each taenia. Two of the five pigs reinfected after 5 months did not develop metacestodes, two showed few caseous non-infective forms and in the fifth pig, 14% of the metacestodes were vesicular and 86% colloidal and caseous. In the six animals challenged 9 months after the first infection, three were heavily infected with vesicular metacestodes and the other three showed only colloid and caseous forms in muscles. All parasites found in brains were vesicular. We conclude that immunity due to primary infection lasts at least 5 months. At 2 months of infection antigens of 24 and 39-42 kDa were the most frequently recognised. In those pigs with only a few caseous cysts in muscles and/or vesicular ones in brains no antibodies were detected.     

Measurement and simulation of evaporation from soil in olive orchards

Evaporation from the soil (E _s) beneath an olive orchard was characterised in a semi-arid Mediterranean climate (Córdoba, Spain). First, the microlysimeter method was modified to measure accurately E _s beneath tree orchards. The variability in irradiance reaching the soil beneath the orchard caused spatial variations in E _s during both evaporation stages. In the first days of the drying cycle, E _s was higher for high irradiance locations but the opposite occurred the subsequent days, although daily differences in E _s between locations progressively declined. For the energy-limiting stage, linear relationships between E _s values and incident photosynthetically active radiation were found for different times throughout the season. The slopes of the relationships were similar, but their intercepts differed substantially, showing the importance of a variable aerodynamic component in determining E _s. A simple functional model was formulated to estimate E _s at daily time steps. During the energy-limiting stage, E _s is calculated as the sum of the equilibrium evaporation at the soil surface and an aerodynamic term, derived from the Penman equation. For the falling rate stage, Ritchie's (1972) approach is adopted for the E _s calculations. The model was successfully tested in an orchard of 6×6 m spacing, typical of intensive olive orchards, under a wide range of evaporative demand conditions. Trees covered around 36% of the soil surface. The model predicted an average seasonal E _s of 286 mm, which represents around one third of the estimated olive evapotranspiration and about 50% of the average seasonal rainfall of the area. Received: 3 August 1998     

Effect of Storage Time on In Vitro Digestibility and Resistant Starch Content of Nixtamal,Masa, and Tortilla

Nixtamal, masa, and tortilla samples were stored for 24–96 hr and their chemical composition, retrogradation, and in vitro starch digestibility features were evaluated. Ash and fat contents in the three products were smaller than in the original corn sample, but protein levels were higher, all in accordance with previous studies. In general, a minor decrease in available starch (AS) content was observed with storage time. Masa showed the greatest AS values, followed by tortilla and nixtamal. Tortilla presented slightly higher retrograded resistant starch (RS3) values (1.1–1.8%, dmb) than masa (0.7–0.9%) and nixtamal (0.7–0.8%) and only minor increases were observed after 24 hr of storage, suggesting that retrogradation phenomenon in these samples takes place very rapidly and is more pronounced in the final product (tortilla). The development of RS3 explains the observed decrease in AS. Higher total resistant starch values were found in all samples at a range of 2.1–2.6% for nixtamal and masa, and a range of 3.1–3.9% in tortilla. This indicates that, apart from retrograded resistant starch, some ungelatinized fractions appear to contibute to the indigestible content of these products. The α‐amylolysis rate of the three materials decreased with storage. Tortilla showed the greatest hydrolysis indices. Differential scanning calorimetry (DSC) analysis showed that the nixtamal, masa, and tortilla did not show differences in amylopectin crystal melting temperature with storage time, but tortilla exhibited higher enthalpy values after 72 hr of storage, in accordance with the greater total RS contents recorded after prolonged storage.     

Effect of Recombinant Bovine Somatotropin on Plasma Concentrations of Insulin‐like Growth Factor I,Insulin and Membrane Integrity of Bull Spermatozoa

This study aimed to evaluate the effect of the exogenous recombinant bovine somatotropin (rbST) on plasma concentrations of insulin‐like growth factor I (IGF‐I), insulin and semen quality of bulls. Twenty bulls (Aberdeen Angus and Brangus) were divided by breed into two groups. Placebo group was injected with NaCl 0.9% (s.c.) and treatment group with rbST (s.c., 500 mg) at days 0 and 14 of the experiment. Immediately after semen collection, blood samples were taken on days 0, 14, 28, 42 and 56 of the experiment. Semen was also collected on day 70 of the experiment. Evaluation of sperm motility was performed at pre‐freezing and post‐thawing stage, whereas assessment of sperm membrane integrity was performed after freezing and thawing. Analysis of data revealed that the effect of treatment and treatment‐by‐collection day on plasma concentrations of IGF‐I and insulin was not significant. However, mean plasma concentrations of IGF‐I and insulin were affected (p < 0.0001) by days of blood sampling. Effect of treatment and treatment‐by‐collection day on motility of spermatozoa was similar (p > 0.05) at pre‐freezing and post‐thawing stage. Intactness of plasmalemma and tail membrane of spermatozoa at post‐thawing stage was higher (p < 0.05) in rbST‐treated group than in control. In conclusion, rbST did not affect plasma concentrations of IGF‐I and insulin, however, it did improve post‐thaw sperm membrane integrity.     

Hydroureteronephrosis and fetal mummification secondary to uterine torsion in a Merino ewe

A 6 year old pluriparous Merino ewe was presented for investigation of a large intra-abdominal mass. Post-mortem examination revealed a 360° clockwise uterine torsion was present with a mummifying fetus. The torsion involved the left ureter resulting in a severe hydroureteronephrosis. Uterine torsion is uncommon in the ewe, occurring in less than 0.1% of pregnancies in one report (Mahmoud et al. Livest Res Rural Dev 2018;30), but cases are likely to be undiagnosed, particularly under the extensive management conditions typical of Australia. The chronicity of the condition in this ewe would support this statement. To the authors' knowledge this is the first reported case of hydroureteronephrosis secondary to uterine torsion in any species.     

Evaporation and canopy conductance of citrus orchards

Evaporation of citrus orchards has been widely studied, but differences in methodologies and management conditions have led to conflicting results, mainly due to differences in ground cover and soil evaporation. In this work the contribution of transpiration and soil evaporation has been studied in a drip-irrigated, clean cultivated mandarin (Citrus reticulata Blanco) orchard on a sandy soil in Southern Spain. Evapotranspiration (ET) was measured using eddy covariance while soil evaporation was determined with microlysimeters, during August 2000 and May 2001. Average ET was 2.6 mm day⁻¹ in August and 2.1 mm day⁻¹ in May. The crop coefficient (K_c) was 0.44 and 0.43 in 2000 and 2001, respectively. The coefficient of transpiration (K_p) was 0.30 in 2000 and 0.25 in 2001. The daily bulk canopy conductance (g_c) ranged from 1.2 to 2.2 (average 1.8) mm s⁻¹ in 2000 and from 1.2 to 2.7 (average 1.9) mm s⁻¹ in 2001. A model of daily canopy conductance as a function of intercepted radiation was derived and applied to calculate the transpiration of orchards with different values of ground cover (GC). The ratio of transpiration over reference ET of mandarin orchards is linearly related to ground cover (K_p = 0.7 GC). Calculated crop coefficients agree with values suggested by FAO for mature orchards (around 0.65) but are substantially lower than FAO values for young plantations.     

Hazard Analysis and Critical Control Points System for a Bull Semen Production Centre

Bull semen production centres (SPC) generally present satisfactory quality control for sperm processing, but non‐standardized hygiene procedures. This study describes a Hazard Analysis and Critical Control Points (HACCP) system developed for bull SPC and subsequently implemented in a commercial SPC. After the identification of hazards at each step of semen processing and the determination of their risk and severity, monitoring and corrective procedures were designed to assess the system's efficiency. The HACCP system identified six microbiological hazards, 10 physical hazards, four chemical hazards and three critical control points. After the establishment of Good Processing Practices, Standard Operating Procedures and Standard Sanitizing Operating Procedures, the system was validated through an audit, to identify eventual failures and to define measures to correct them.     

Recombinant S3Pvac-phage anticysticercosis vaccine: Simultaneous protection against cysticercosis and hydatid disease in rural pigs

This paper provides macroscopic and histological evidence on the statistically significant protective effects of S3Pvac-phage vaccination against porcine cysticercosis and hydatidosis. The study included 391 rustically bred pigs (187 vaccinated and 204 controls). Vaccination significantly reduced the prevalence of cysticercosis by 61.7%. Vaccination also significantly reduced by 56.1% the prevalence of hydatidosis caused by Echinococcus granulosus in pigs. The presence of the vaccine epitopes in both cestodes is probably involved in the cross-protection observed. Increased inflammation was found in 5% of cysticerci recovered from controls, versus 24% from vaccinated pigs (P<0.01). Hydatid cysts were non-inflammatory in either group. Vaccination was effective to prevent one single disease, but it failed to prevent the simultaneous infections with both parasites in a same pig. The widening of the S3Pvac-phage vaccine protective repertoire to include hydatidosis is a convenient feature that should reduce the prevalence of two frequent zoonoses that affect rustic porcine breading with a single action. Thus, the costs of two different vaccination programs would be reduced to a single one with significant reduction in both zoonoses.