Effect of herb-clover mixes on weaned lamb growth : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palerston North, New Zealand

The quality and production of ryegrass (Lolium perenne L.) /white clover (Trifolium \nrepens) pastures are seasonal in New Zealand. Earlier research showed that a sward \nmix of plantain (Plantago lanceolata), chicory (Cichorium intybus L.), white- and \nred-clover (Trifolium pratense) resulted in greater lamb live weight gains in the late \nsummer early autumn period. However, this has not been tested across all the \nseasons in New Zealand. \nTherefore, research was undertaken for two consecutive years (2011/2012 and \n2012/2013) on three sward mixes; Pasture mix, Plantain mix and Chicory mix in \nearly spring, late spring and early summer (late spring), summer and autumn. The \nPasture mix consisted of perennial ryegrass and white clover. The Plantain mix \nconsisted of plantain, white- and red-clover. The Chicory mix consisted of plantain, \nchicory, white- and red-clover. It was hypothesised that lamb performance (live \nweight, live weight gain (LWG) and carcass weight) and apparent carcass weight \nproduction per ha would be greatest in the Plantain and Chicory mixes in all four \nperiods. Secondly it was hypothesised that Plantain and Chicory mixes would have \nlower feed conversion ratios (FCR) with higher herbage utilization efficiencies \n(EHU%) than the Pasture mix. \nIn each period weaned lambs were reared in the three herbage treatments for a \nmaximum of two months. Lambs were weighed fortnightly and they were \nslaughtered within 12 hours of being off the pasture at the end of the experiment. \nCarcass weights were obtained from the abattoir. \nThe Plantain and Chicory mixes had a higher feeding value than the Pasture mix \nduring early spring to autumn. Both Plantain and Chicory mixes produced heavier \n(P<0.05) lambs, higher (P<0.05) live weight gains (LWG) and carcass weights \ncompared to the Pasture mix in all periods. Total apparent carcass weight production \nper ha were 407, 748 and 709 kg/ha in year one and 474, 607 and 642 kg/ha in year \ntwo in the Pasture mix, Plantain mix and Chicory mix, respectively. Both Plantain \nand Chicory mixes had lower (P<0.05) feed conversion ratios (FCR) and higher \n(P<0.05) herbage utilization efficiencies (EHU%) compared to the Pasture mix. \nThis research has shown that sheep farmers in New Zealand can finish lambs at a \nfaster rate for heavier carcasses using herb-clover mixes from spring to autumn than \non ryegrass/white clover pastures.