Relative Abilities of Young Sheep and Goats to Self-Medicate with Tannin-Rich Sainfoin When Infected with Gastrointestinal Nematodes

Plant secondary metabolites (PSM) are one of the promising options to control gastrointestinal nematodes in sheep and goats. The objective of this study was to assess the abilities of sheep and goats to self-medicate with tannin-rich sainfoin (Onobrychis viciifolia) (SF) when infected with gastrointestinal nematodes, using a cafeteria and an operant conditioning trial. Hypotheses were that parasitized (P) lambs and goat kids would show greater intake and preference for SF than their non-parasitized (NP) counterparts, that kids would eat more SF than lambs (due to their lower resistance against parasites and their greater ability to consume PSM), and that SF intake would increase over time for P animals. We used 20 female kids and 20 ewe lambs aged 3 months. Half of the animals per species (n = 10) were experimentally infected with 170 L3 larvae of Haemonchus contortus/kg of BW (P). The other half were free from parasites throughout the study (NP). Five weeks after infection, animals were exposed to a 24-day cafeteria trial (three 8-day periods) offering a free choice between two legume pellets: SF (3.8% condensed tannins) and alfalfa (ALF, Medicago sativa; no tannin). Subsequently, animals were involved in an operant conditioning trial of two 4-day long sessions, to assess in short-term tests their motivation to walk for a SF reward when offered in choice with freely available ALF. In the cafeteria trial, SF preference was greater in kids than in lambs, particularly in the first two periods. We did not observe a greater preference for SF in P animals, which was even greater in NP animals for periods 1 and 2. Sainfoin intake increased through periods for P animals, which led to similar SF preferences for all groups during period 3. In the operant-conditioning trial, motivation to get the SF reward was similar between P and NP animals. These results support the hypotheses that goats are more willing to consume tanniferous feeds than sheep, and that P animals increased SF intake through time. However, the emergence of a curative self-medicative behaviour was not supported, as P individuals did not show greater SF intake, preference, nor a greater motivation to get SF than NP animals, regardless of animal species. These findings are discussed with previous results and some explanations are presented

RAIM performance in presence of multiple range failures

International audienceIt is currently stated and widely accepted by industry and users that the RAIM is designed to provide timely warnings in the situation where only one of the range measurements used at the current epoch is affected by an unacceptable bias. However, given the range of potential applications of RAIM in the future, in particular with the advent of Galileo and the generalization of Safety of Life applications, which should spread from the civil aviation community to many other professional sectors, it is very important to better understand the fundamental properties of RAIM, and in particular the potential of RAIM to detect multiple failures on range measurements. The purpose of the study presented in this paper is to analyze the performance of a RAIM in the presence of multiple simultaneous range errors. In particular, we conduct a theoretical analysis to determine in which cases the Least Squares Residuals RAIM detection criterion is not affected, and analyzed results of Monte-Carlo simulations in presence of up to four range failures. The theoretical analysis outlined above aims at determining in what conditions the Least Squares Residuals RAIM detection criterion remains unaffected by multiple range failures, searching for what we call criterion unaffecting range errors. We show that, provided the satellite constellation does not have any degenerated geometrical properties, the dimension of the vector sub-space of these criterion unaffecting errors is max(4-(N-p),0), where N is the number of tracked satellites and p is the number of faulty pseudorange measurements. The immediate conclusion is that if N-4 pseudo range measurements are affected, or less than that, by a large error, there exists no error that will not affect the RAIM detection criterion, and globally due to the negligible probability that unintentional interference lies in a small dimension sub-space, the RAIM detection criterion exhibits a natural detection capability even if up to N-2 pseudo-range measurements are faulty. This theoretical result defines the properties of the errors that lead to zero change in the detection criterion. To jump to a more operational conclusion, it remains to know what the possibility is for multiple range errors to induce a detection criterion that is below the detection threshold. So to complement the theoretical analysis outlined above, we ran Monte Carlo simulations inserting up to four range failures and analyzing the detection capacity. The capacity of RAIM detection is also analyzed in the presence of intentional jamming