From the get-go: Dietary exposure in utero and in early life alters dietary preference in later life

Abstract

The objectives were to determine the effect of in utero and early-life dietary exposure to a diverse diet or a perennial ryegrass (Lolium perenne L.) diet on grazing behavior and dietary neophobia of lambs ~3.5 months post-weaning (weaned at 6 weeks of age). Sixty-four Coopworth lambs (152.5 ± 1.4 d of age; mean ± SEM,) were used. Sixteen lambs had previous in utero exposure to the diverse diet (INDIV) and another 16 had in utero and early life (from birth to weaning at 42 ± 2 d of age) exposure to the diverse diet (ELDIV) of ryegrass, red clover (Trifolium pratense L.), plantain (Plantago lanceolata L.), chicory (Cichorium intybus L.), and alfalfa (Medicago sativa L.). Sixteen lambs had only in utero exposure to ryegrass (INRYE) and the other 16 had early life exposure to ryegrass (ELRYE). Lambs were randomly allocated to one of 16 paddocks (n = 4 per treatment) with 4 lambs per paddock. All paddocks contained equal areas of spatially separated strips of red clover, chicory, alfalfa, plantain, and ryegrass, of which arrangement within the paddock was randomized. Every 5 min from 0620 to 2105 h, trained observers recorded the behavior (grazing, idle, and ruminating) and the location (pasture species) of each lamb. The INRYE and ELRYE lambs tended to (P ≤ 0.10) and spent more time (P < 0.05) grazing within ryegrass than their diverse treatment counterparts, respectively. The ELRYE treatment spent longer grazing in ryegrass, a product of increasing bout number within ryegrass (P < 0.05) and the INRYE treatment had longer bouts within ryegrass compared with their diverse treatment counterparts. Further, the INRYE and INDIV treatments spent less time grazing ryegrass than the other treatments (P < 0.05). The ELDIV and ELRYE treatments in general had a reduced latency to graze pasture species compared to the other treatments. Further, all lambs ate a mix of the forages offered. Exposure in utero and early in life affected the preferences of lambs exposed to diverse species after weaning. Such effects were still seen ~3.5 months after weaning and differences between treatments were more prominent in lambs exposed in the early life treatment group compared with the in utero treatments. Exposure to ryegrass in utero and early in life exposure pre-disposed animals to prefer ryegrass later in life, while diverse diet exposure appeared to reduce dietary neophobic behavior.