Validation of a Feeding Stimulant Bioassay Using Fish Hydrolysates for the Pacific White Shrimp,Litopenaeus vannamei

A protocol for testing feeding stimulants on Pacific white shrimp, Litopenaeus vannamei, is described. Thirty‐five rectangular tanks (55 L volume) served as the test system into which ten 5–6 g shrimp were stocked. Every tank contained two bowls, each of which contained either 25 feed pellets of a Reference Diet or Test Diet (consisting of the Reference Diet with one test ingredient added). After 1 h, the difference between the number of pellets consumed of the Test Diet and the Reference Diet was used as the Response. Each of the four Test Diets contained a different salmon hydrolysate made from by‐products of the Alaska fish processing industry (included at 50 g/kg). A fifth commercial shrimp diet was also tested. Each Test Diet was tested against the Reference Diet over a 4‐d period in seven replicate tanks. The data were subjected to a one‐way ANOVA and a confidence interval for each treatment response was calculated. The confidence interval was used to assess the test ingredient as a feeding stimulant. Treatment means were compared using Tukey's test (α = 5%). All the hydrolysates tested were found to act as feeding stimulants.     

BANAD: A farm model for ex ante assessment of agro-ecological innovations and its application to banana farms in Guadeloupe

The ex ante assessment of innovative agro-ecological innovations is a key step in the development of more sustainable crop management systems. To this end, models are useful tools because they make it possible to rapidly assess numerous innovations in different contexts. Whereas many farm optimisation models focusing on the farmer’s strategic decision to adopt new crop management systems have been published, little attention has been given to the ex ante modelling of the dynamic operational impacts of innovation adoption at the farm level. BANAD, a mechanistic model for such applications, is proposed. It allows the ex ante assessment of innovative management systems including new agro-ecological techniques, while taking into account different farming contexts and policy and market conditions. It includes three components: (i) a crop management system model, (ii) a crop model (SIMBA) and (iii) a farming system model. Our results applied to the ex ante assessment of six innovative banana management systems for three contrasted farm types in Guadeloupe showed that the impacts of agro-ecological innovations, which include rotations, improved fallow, intercropping, pest-resistant cultivar, and an integrated organic system, can vary considerably according to (i) the farm type in which the innovation is integrated, (ii) the nature of the agro-ecological innovations, and (iii) the criteria considered and the temporal horizon of the assessment. Innovative intercropping systems that were effective at the field level in terms of the yield improvement and decreased pesticide use could be problematic at the farm level because they increased the workload and decreased income. The adoption of rotations or improved fallow seemed to be relevant for smallholders but could induce a critical period of 1.5-2.5 years during which income decreased drastically. Under certain conditions of markets and subsidies, very environmentally friendly innovations that are less productive can however be economically effective.