The influence of season on lambs' feeding preference for plantain, chicory and red clover

Abstract

The objective of the three studies reported here was to examine the grazing preference and diet selection of lambs for plantain (Plantago laceolata), chicory (Cichorium intybus L.) and red clover (Trifolium pratense) compared with New Zealand’s conventional ryegrass (Lolium perenne) pasture. Study One investigated the diet selection of lambs for 7 days at the beginning of March, using transects with tagged plants on a mixed plantain, chicory and red clover sward. Study Two was an outdoor preference experiment conducted in both March and May by observation of lambs on adjacent monocultures of plantain, chicory and red clover. Study Three was an indoor feeding trial that aimed to determine the intake rate and relative preference of weaned lambs for two herbages (chicory and plantain), two legumes (lucerne and red clover) and ryegrass pasture, in both spring (November) and summer (March). Study One determined that when grazing the mixed sward for a period of 7 days, the mean day that lambs commenced grazing red clover, chicory and plantain was Day 1.6 ± 0.1, 4.8 ± 0.2 and 6.2 ± 0.2, respectively, with significant (P < 0.05) differences between all species. In relation to preference as observed in Study Two, more lambs (P < 0.05) were seen to be grazing red clover at any time, and more lambs were grazing chicory (P < 0.05) than plantain. There was, also an interaction of season with preference, with plantain becoming more acceptable (P < 0.05) to the lambs in May (late autumn) versus March (early autumn). In Study Three, the term ‘preference’ refers to the natural logarithm of the ratio of amounts eaten between the forage being tested and the alternative forage offered simultaneously. This was established in triplicate by offering pairs of all the plant species side by side to individually penned lambs. The results indicated that plantain was consumed at a similar rate (P > 0.05) to that of ryegrass, whereas red clover and chicory had higher voluntary feed intakes, likely due to lower fibre content. The intake rate of chicory was greater in summer than spring and may be related to increased palatability due to the increased water-soluble carbohydrate content of chicory in summer. Regardless of season, average preference for red clover was always higher (P < 0.05) than that of chicory, plantain and ryegrass. Plantain was considerably less preferred in summer than spring. Differences in diet selection and preference may offer a unique opportunity to manipulate utilisation of pastures using a diverse range of plant species.