Caprine in utero learning and feed neophobia

Abstract

Environmental driven changes in meat goat production systems in Vietnam require the use of new feedstuffs in the diets for goats. The introduction of novel feedstuffs to young goats is often associated with a reduced feed intake, daily gain and welfare. The work presented here investigated different learning strategies to increase the preference for flavour cues and ingredients after weaning. It was hypothesized that goat kids may learn flavour preferences from their mother during pregnancy or during lactation and that this learning improves the intake of novel ingredients after weaning. Chromoneala odorata was chosen as a model feedstuff to study neophobia in goats. C. odorata, however, has a strong smell and adult goats are reluctant to consume this plant voluntarily. Therefore, C. odorata was selected as a test feedstuff because it was anticipated that the intake of C. odorata would result in a high contrasts compared to control animals. The first experiment was designed to test the hypothesis that feeding C. odorata to pregnant goat dams increases the acceptance of this plant by their offspring. It was found that kids born from does that were exposed to C. odorata during pregnancy consumed more of this plant. This finding indicated that the kids learned in utero about C. odorata. Due to the experimental design, however, it could not be excluded that the process of adaptation to C. odorata was caused by the consumption of the milk instead of during pregnancy. Therefore, a second experiment was designed to investigate whether the process of adaptation to C. odorata was related to either the in utero period of the goat kids or to the subsequent suckling period. It was hypothesized that kids born to dams fed C. odorata during pregnancy and receiving milk from dams not exposed to C. odorata during pregnancy show an improved acceptance to consume this plant. This experiment corroborated the outcome of the first experiment in that kids learned in utero about C. odorata. An attempt was made to provide a clue about the underlying mechanism to manipulate postnatal feeding behaviour (third experiement). Therefore, the importance of the phase of pregnancy on in utero learning of C. odorata by goats was evaluated by comparing mid with late pregnancy exposure to C. odorata of the pregnant does. It appeared that the transmission of feeding preference from mother to offspring occurred during late gestation and that it remains present at least 3 months after weaning in goats. Finally, the idea was tested whether kids would consume more C. odorata after experiencing the flavour through the mother’s milk (fourth experiment). It was hypothesized that exposure of C. odorata to the dams during both pregnancy and lactation versus pregnancy alone, further increased post-weaning intake of C. odorata by their offspring. However, it appeared that the transmission of feeding behaviour from goat dams to offspring did not occur during lactation. The concept of in utero learning in goats, however, again was confirmed.