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
repens) pastures are seasonal in New Zealand. Earlier research showed that a sward
mix of plantain (Plantago lanceolata), chicory (Cichorium intybus L.), white- and
red-clover (Trifolium pratense) resulted in greater lamb live weight gains in the late
summer early autumn period. However, this has not been tested across all the
seasons in New Zealand.
Therefore, research was undertaken for two consecutive years (2011/2012 and
2012/2013) on three sward mixes; Pasture mix, Plantain mix and Chicory mix in
early spring, late spring and early summer (late spring), summer and autumn. The
Pasture mix consisted of perennial ryegrass and white clover. The Plantain mix
consisted of plantain, white- and red-clover. The Chicory mix consisted of plantain,
chicory, white- and red-clover. It was hypothesised that lamb performance (live
weight, live weight gain (LWG) and carcass weight) and apparent carcass weight
production per ha would be greatest in the Plantain and Chicory mixes in all four
periods. Secondly it was hypothesised that Plantain and Chicory mixes would have
lower feed conversion ratios (FCR) with higher herbage utilization efficiencies
(EHU%) than the Pasture mix.
In each period weaned lambs were reared in the three herbage treatments for a
maximum of two months. Lambs were weighed fortnightly and they were
slaughtered within 12 hours of being off the pasture at the end of the experiment.
Carcass weights were obtained from the abattoir.
The Plantain and Chicory mixes had a higher feeding value than the Pasture mix
during early spring to autumn. Both Plantain and Chicory mixes produced heavier
(P<0.05) lambs, higher (P<0.05) live weight gains (LWG) and carcass weights
compared to the Pasture mix in all periods. Total apparent carcass weight production
per ha were 407, 748 and 709 kg/ha in year one and 474, 607 and 642 kg/ha in year
two in the Pasture mix, Plantain mix and Chicory mix, respectively. Both Plantain
and Chicory mixes had lower (P<0.05) feed conversion ratios (FCR) and higher
(P<0.05) herbage utilization efficiencies (EHU%) compared to the Pasture mix.
This research has shown that sheep farmers in New Zealand can finish lambs at a
faster rate for heavier carcasses using herb-clover mixes from spring to autumn than
on ryegrass/white clover pastures.