Molecular investigation and diagnosis of three genetic diseases in Arabian horses from Middle East and North American populations

Abstract

Maternal docosahexaenoic acid (DHA) status has been shown to influence cognitive development in infants and children. Improvements in learning ability might enhance trainability of horses, which could lead to better athletic performance and decreased behavioral problems. To assess the cognitive benefits of early exposure to DHA, offspring of mares fed a fat supplement containing an algae source of DHA (n¼10) or a placebo fat supplement (CON, n¼10) from d 250 of gestation through 74 d of lactation were evaluated. Using operant conditioning, foals had been taught to touch a target object with their nose upon verbal command at 2 mo of age. This study evaluated memory recall of previous training, as well as performance on new, more complex tasks using the same target training technique in weaned foals (meanSEM, 185 � 2 d of age). We hypothesized that weanlings exposed to DHA would have better memory recall and progress further and with greater ease through a series of new tasks than weanlings exposed to CON. With researchers blinded to treatment, weanling response times, performance scores, and the number of cues needed to successfully complete each behavior were recorded during 11 training sessions conducted over 6 d. Data were analyzed using a two-tail t-test or zero inflated Poisson model. Memory recall of previous training was evaluated during the first 2 sessions by repeating the original targeting behaviors. Based on performance scores, all foals demonstrated recall of previous training (P< 0.0001). Mean response time during session 1 was slower (P ¼ 0.031) than session 2, indicating optimal recall may not be achieved when first re-exposed. Memory recall was not affected by DHA exposure or sex of the foal. New behavior training (sessions 3-11) was comprised of tar- geting tasks that progressed in difficulty, including walking from point A to B, performing target behaviors in an open environment, walking over novel objects (black stall mat and wooden platform), and loading into a live- stock-hauling trailer. Overall, weanlings exposed to DHA were more likely to score lower (P ¼ 0.016) than CON weanlings on new training tasks. DHA weanlings scored lower (P ¼ 0.013) and required more cues (P ¼ 0.037) to successfully complete the platform task compared to CON weanlings, whereas performance on all other individual tasks was unaffected by maternal diet. When performance on the platform was excluded from analysis, DHA wean-