Effect of parity and progesterone priming on induction of reproductive function in Saanen goats by buck exposure

The response to the buck effect and the use of progesterone priming was studied in Saanen goats during the non-breeding season (April and May) in northern Mexico (26° N). Forty goats were assigned randomly in equal numbers (n = 10) to four treatment groups in a 2 × 2 factorial arrangement. Treatment consisted of two dosages of progesterone (P4) (0 or 5 mg) and two categories of goats, nulliparous and multiparous. Both parity groups were exposed to sexually active bucks previously exposed to a long-day photoperiodic scheme (16 h light day^− 1). All multiparous goats (20/20) displayed estrous behavior within the first 10 days of buck exposure, while 70% (14/20) of the nulliparous goats showed estrus (P > 0.05). During the first five days of buck exposure, the percentage of unprimed goats in estrus was 70% points lower than the primed goats, although progesterone priming did not affect the occurrence of estrus (90% vs 80%; P > 0.05) after 10 days of buck stimulus. The time to onset of estrus was four days shorter (P < 0.05) in P4-treated goats compared with controls. Pregnancy rate did not differ between primed and unprimed goats (80 vs 60%; P > 0.05), but this variable was higher (P < 0.05) in multiparous than nulliparous goats (95 vs 45%). It was concluded that it is possible to induce fertile estrus in Saanen goats during the non-breeding season in northern Mexico using sexually active bucks. The use of progesterone priming can accelerate the response of goats to the buck stimulus although it was ineffective in improving the pregnancy rate of goats. Additionally, a higher proportion of the multiparous goats got pregnant compared with the nulliparous goats induced to estrus by the buck stimulus.     

An in situ single-pass perfusion model for assessing absorption across the intestinal mucosa of the brushtail possum

AIM: To develop an in situ animal model for assessing absorption of molecules across the intestinal mucosa of possums.

METHODS: A surgical preparation was used to perfuse known concentrations of reference compounds (fluorescein and luteinising hormone-releasing hormone; LHRH) through measured sections of selected regions (jejunum, caecum, proximal colon) of the intestinal tract of 19 possums, over a 2-h period. Plasma concentrations of the compounds, which were perfused either with or without co-administration of a permeation enhancer (sodium deoxycholic acid; SDA), were determined in the perfusion effluent, peripheral and in some instances in the pre-hepatic circulation by spectrofluorometry (fluorescein) or radio-immunoassay (LHRH). Pharmacokinetic parameters of both compounds in the possum were determined over a period of up to 4 h in a further 30 animals (fluorescein, n=6; LHRH n=24), from their plasma profiles following intravenous (I/V) administration of a bolus dose.

RESULTS: In animals perfused with 25 mg/ml fluorescein (Perfusion Experiment (PE) 1), the mean plasma concentration was 2.8 (SE 0.12) µg/ml in post-hepatic blood samples. When possums were perfused with 2.5 mg/ml fluorescein and 7 µg/ml LHRH (PE 2), mean plasma concentrations were 0.3 (SE 0.01) and 7.8 (SE 1.64) µg/ml fluorescein and 0.1 (SE 0.02) and 6.3 (SE 0.45) ng/ml LHRH, in the absence and presence of permeation enhancer, respectively. There was a poor correlation between pre-hepatic and post-hepatic concentrations.

CONCLUSIONS: The single-pass in situ perfusion technique provided a useful model for investigating basic information on the absorption of biocontrol agents across the intestinal tract of possums, but had limitations that must be recognised.     

Economic assessment of shade-cloth covers for agricultural irrigation reservoirs in a semi-arid climate

We assess the economics of investing in suspended shade-cloth covers (SSCCs) in agricultural water reservoirs (AWRs) to reduce evaporation losses and save water for irrigation in arid and semi-arid areas. In particular, we examine the use of SSCCs in the Segura River Basin (southeastern Spain). The decision to install a cover depends on the potential evaporation losses, reservoir characteristics, cover effectiveness, the value of water, filtration requirements, water salinity, government subsidies and the installation, operation and maintenance costs. The economic viability of the investment increases with the value of the saved water, i.e., with water scarcity, and is greater when water quality is poor. Hence SSCCs can be helpful in arid and semi-arid regions facing water shortages and water quality problems. The farm-level decision to install a cover depends largely on the cost of purchasing water, when water is generally available, and the profit from increased crop production or enlarged farmlands, when water is scarce.     

Institutionalizing agroecology: successes and challenges in Cuba

Over the past two decades, Cuba has become a recognized global leader in sustainable agriculture. This paper explores how this process of agricultural transition has taken place, and argues that it has largely been led by research institutes, non-state organizations and the Cuban government, which have all contributed to the institutionalization of agroecology in both policy and practice. This process has been highly effective in terms of the numbers of people using agroecological techniques. However, although these techniques have been widely adopted by farmers across the country, this paper suggests that many still perceive maximizing production to be a higher priority than maintaining a commitment to agroecological ideals. For these farmers, agroecological farming is viewed primarily as a pragmatic decision rather than an ideological or moral one, and they may thus be susceptible to shifting back to conventional production if this option became politically and economically feasible

Optimizing Tilapia, Oreochromis sp., Marketing Strategies in Nicaragua: A Mixed-integer Transshipment Model Analysis

Tilapia, Oreochromis sp., production has increased in the Central American region in recent years. Yet, commercial tilapia aquaculture has not developed in Nicaragua on the scale that it has in other neighboring countries. Although demand for tilapia products exists, lack of thorough understanding of domestic markets and coordinated production and marketing efforts have hampered the development of a domestic market. The objectives of this study were to quantify domestic marketing costs for tilapia produced in Nicaragua and develop a mixed-integer transshipment mathematical programming model to identify the most profitable marketing alternatives for tilapia farmers. Results suggested targeting primarily outlets with higher sales prices such as restaurants with supplemental production delivered to local supermarkets. The model chooses cities with weekly restaurant demand capable of absorbing the farm's production with excess product sold to alternative outlets. Supply of farm-raised tilapia production in most regions of Nicaragua was insufficient and created problems associated with frequent and dependable deliveries required by higher paying outlets (restaurants and supermarkets). Larger farms will generate greater returns with regular consistent deliveries to higher priced restaurant outlets. Smaller farms with limited production volumes were not able to meet weekly delivery requirements. Biannual deliveries reduced transportation cost and sales price and were not profitable. However, sustaining markets with infrequent deliveries may not be feasible. This analysis provides guidelines for targeting those specific markets that optimize returns to specific farm sizes in specific regions.     

Natural infection of broiler breeder chickens with endemic apathogenic Newcastle disease virus and their subsequent response to vaccination with a live V4 Newcastle disease virus vaccine

Flocks of broiler breeder chickens housed on a commercial farm were monitored from 13 w of age for natural infection with endemic lentogenic Newcastle disease virus (NDV). Seroconversion was first detected at 17 w. By 24 w, all 8 flocks had achieved peak log2 mean haemagglutination inhibiting antibody titres of up to 4.8. Antibody titres then declined and rose again over several months, suggesting cyclic reinfection with NDV. A lentogenic NDV indistinguishable from V4 was isolated from the cloaca of one bird at 18 weeks of age. At 54 weeks of age, 6 of 8 flocks were vaccinated en masse with live V4 NDV vaccine, 3 flocks by drinking water and 3 flocks by aerosol. All flocks were serologically monitored for a further 8 w. Drinking water vaccination induced an anamnestic response in 3 flocks, showing that flocks with pre-existing active immunity to NDV may be successfully vaccinated with V4. However, in all aerosol vaccinated flocks, the procedures failed to induce a response different to that observed in unvaccinated flocks. The serological response to vaccination was greater in sires than in dams.     

Echinacea species and alkamides inhibit prostaglandin E(2) production in RAW264.7 mouse macrophage cells

Inhibition of prostaglandin E(2) (PGE(2)) production in lipopolysaccharide-stimulated RAW264.7 mouse macrophage cells was assessed with an enzyme immunoassay following treatments with Echinacea extracts or synthesized alkamides. Results indicated that ethanol extracts diluted in media to a concentration of 15 microg/mL from E. angustifolia, E. pallida, E. simulata, and E. sanguinea significantly inhibited PGE2 production. In further studies, PGE2 production was significantly reduced by all synthesized alkamides assayed at 50 microM, by Bauer alkamides 8, 12A analogue, and 14, Chen alkamide 2, and Chen alkamide 2 analogue at 25 microM and by Bauer alkamide 14 at 10 microM. Cytotoxicity did not play a role in the noted reduction of PGE2 production in either the Echinacea extracts or synthesized alkamides. High-performance liquid chromatography analysis identified individual alkamides present at concentrations below 2.8 microM in the extracts from the six Echinacea species (15 microg/mL crude extract). Because active extracts contained <2.8 microM of specific alkamide and the results showed that synthetic alkamides must have a minimum concentration of 10 microM to inhibit PGE2, it is likely that alkamides may contribute toward the anti-inflammatory activity of Echinacea in a synergistic or additive manner.