Benefits and risks of including the bromoform containing seaweed Asparagopsis in feed for the reduction of methane production from ruminants

The agricultural production of ruminants is responsible for 24% of global methane emissions, contributing 39% of emissions of this greenhouse gas from the agricultural sector. Strategies to mitigate ruminant methanogenesis include the use of methanogen inhibitors. For example, the seaweeds Asparagopsis taxiformis and Asparagopsis armata included at low levels in the feed of cattle and sheep inhibit methanogenesis by up to 98%, with evidence of improvements in feed utilisation efficiency. This has resulted in an increasing interest in and demand for these seaweeds globally. In response, research is progressing rapidly to facilitate Asparagopsis cultivation at large scale, and to develop aquaculture production systems to enable a high quality and consistent supply chain. In addition to developing robust strategies for sustainable production, it is important to consider and evaluate the benefits and risks associated with its production and subsequent use as an antimethanogenic feed ingredient for ruminant livestock. This review focuses on the relevant ruminal biochemical pathways, degradation, and toxicological risks associated with bromoform (CHBr3), the major active ingredient for inhibition of methanogenesis in Asparagopsis, and the effects that production of Asparagopsis and its use as a ruminant feed ingredient might have on atmospheric chemistry

Development of a method to cryopreserve Greenshell mussel™ (Perna canaliculus) veliger larvae

Cryopreservation of larvae of Greenshell™ mussel Perna canaliculus, the most cultivated species in New Zealand, can provide flexibility for selective breeding programmes and enhance its global production. In this study, we set out to develop a reliable protocol for freezing D-stage larvae of Greenshell™ mussels that ensured long-term survival for successful rearing of thawed larvae in the hatchery. The effects of different combinations of cryoprotecting agents (CPA), varying CPA equilibration times, larval concentrations per straw as well as different larval development stages (48 h vs 72 h old) were evaluated by assessing the behavioural response (swimming activity, algal consumption), shell size and survival of larvae, up to 4 days post-thawing. The protocol yielding the best larval performances was a combination of the following CPA (final concentrations): 14% ethylene-glycol (EG) + 0.6 M trehalose (TRE) + 1% polyvinyl-pyrrolidone (PVP), prepared with Milli-Q water. Stocking densities ranging from 50,000 to 150,000 larvae per straw (0.25 mL) and a 20 min equilibration time gave the best results, while no significant differences in fitness were found between larvae cryopreserved at 48 h nor 72 h-old. Using the improved cryopreservation protocol, over 50% of previously cryopreserved D-larvae were able to survive after 4 days of rearing, compared with 65% in the unfrozen control. More importantly, about one third of thawed larvae were able to swim and feed, and to potentially develop further. These findings contribute to enhance the selective breeding programmes for this species.Xunta de GaliciaMinistry for Business, Innovation and Employment (New Zealand) Shellfish Aquaculture Ref. CAWX180

Cryopreservation of Pacific oyster (Crassostrea gigas) larvae: Revisiting the practical limitations and scaling up the procedure for application to hatchery

International audiencePacific oyster Crassostrea gigas is one major species for aquaculture, and the development of breeding programs and the need for preservation of wild stock genetic resources prompted the need for larvae cryopreservation. The objective of the present study was to choose the most reliable protocol from several existing publications, to test its biological and practical limitations, and to adapt it to hatchery conditions. The selected protocol was characterized by a very slow freezing rate without seeding, and by the use of ethylene glycol and sucrose as cryoprotectant. The best survivals after thawing and rearing up to 48 h post fertilization (hpf) were obtained with larvae that were frozen at late trochophore (20 hpf) and early-D (24 hpf) stages. Increasing the larvae concentration in the straws and using high throughput straw filling and freezing devices did not alter the cryopreservation outcome. The whole procedure was applied to cryopreservation in a commercial hatchery (Satmar, France), and the thawed larvae yielded 9.4 ± 4.5% survivals at 12 days post fertilization. The overall success was dampened by some variability in the larvae survival that is likely due to the physiological status of the larvae. In all, the proposed procedure is robust and reliable and can be used for cryobanking of oyster genetic resources

Maintenance of cyanotoxin production by cryopreserved cyanobacteria in the New Zealand culture collection

A culture collection of freshwater planktonic and benthic cyanobacteria collected from sites across New Zealand has been established at the Cawthron Institute, Nelson, New Zealand. Limited resources led to uncertainty regarding the long-term maintenance of this collection. The present study demonstrates cryopreservation to be a viable method for long-term storage of cyanobacteria. Seventeen of 20 strains evaluated were successfully cryopreserved using the permeating cryopreservation agent dimethyl sulfoxide (Me2 SO), at a final concentration of 15% (v/v). Cyanotoxin analysis was undertaken on selected strains known to produce microcystins, nodularin, anatoxin-a, and saxitoxins. All strains retained their ability to produce these toxins following cryopreservation

Greenshell™ Mussels: A Review of Veterinary Trials and Future Research Directions

The therapeutic benefits of Greenshell™ mussel (GSM; Perna canaliculus) preparations have been studied using in vitro test systems, animal models, and human clinical trials focusing mainly on anti-inflammatory and anti-arthritic effects. Activity is thought to be linked to key active ingredients that include omega-3 polyunsaturated fatty acids, a variety of carotenoids and other bioactive compounds. In this paper, we review the studies that have been undertaken in dogs, cats, and horses, and outline new research directions in shellfish breeding and high-value nutrition research programmes targeted at enhancing the efficacy of mussel and algal extracts. The addition of GSM to animal diets has alleviated feline degenerative joint disease and arthritis symptoms, and chronic orthopaedic pain in dogs. In horses, GSM extracts decreased the severity of lameness and joint pain and provided improved joint flexion in limbs with lameness attributed to osteoarthritis. Future research in this area should focus on elucidating the key active ingredients in order to link concentrations of these active ingredients with their pharmacokinetics and therapeutic effects. This would enable consistent and improved efficacy from GSM-based products for the purpose of improved animal health