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Lincoln University (2019)

Agronomic potential of Lupinus polyphyllus L. for dryland Merino properties in the Mackenzie Basin

Ryan-Salter, Travis P.

Titre : Agronomic potential of Lupinus polyphyllus L. for dryland Merino properties in the Mackenzie Basin

Auteur : Ryan-Salter, Travis P.

Université de soutenance : Lincoln University

Grade : Doctor of Philosophy (PhD) 2019

Résumé partiel
This research examined the potential of Lupinus polyphyllus L. (also known in New Zealand as perennial lupin and Russell lupin) as a productive pasture component for high-country pastures. To do this, a combination of on-farm studies, controlled field experiments and glasshouse experiments were carried out. Throughout the thesis, lucerne (Medicago sativa L.) was used as a control. The use of perennial lupin as a suitable feed for a commercial Merino ewe flock was evaluated in an on-farm study at Sawdon Station, Lake Tekapo. The performance of ewes and lambs grazing a lupin-based pasture was compared with a control flock that was predominantly grazing lucerne. The lupin pasture grew rapidly during the spring period and average pasture cover increased by about 4500 kg of dry matter (DM)/ha under a stocking rate of 15-17 stock units/ha. At tailing in December 2012 and 2013, lambing averaged 111% and ewes averaged 58 kg for the lupin pasture, and 105% and 62 kg for the control flock, while lambs averaged 19 kg for both mobs. At weaning in February 2013, ewes and lambs on the lupin pasture averaged 58 kg and 28 kg compared with 63 kg and 31 kg for the control flock, respectively. During autumn, ewes on the lupin pasture gained 3.8 kg compared with 5.5 kg for the control flock before mating in May. In September, the ewes were shorn and wool averaged 4.62 kg/ewe for the lupin mob and 4.92 kg/ewe for the control flock, with a mean fibre diameter of 18.5 µm. A selection of L. polyphyllus samples were subjected to wet chemistry analyses, which was later used to calibrate a near infrared spectroscopy analyser and predict the nutritional composition of lupin material. Lupin lamina was consistently high in metabolisable energy (11.3-12.6 MJME/kg DM) and crude protein (24-33%) throughout the growing season. Under controlled experimental conditions at Lincoln University, sheep liveweight gain from a dryland mixed cocksfoot (Dactylis glomerata L.)-lupin pasture was 810 kg/ha compared with 1227 kg/ha from dryland lucerne over a 15-month period. This difference was primarily driven by the amount of palatable feed consumed by the sheep, which was 7330 kg DM/ha for cocksfoot-lupin compared with 10,922 kg DM/ha for lucerne. The abundance of lupin in the mixed pasture declined from 40% of the total herbage offered, during the first autumn after sowing (March to May, 2014), to 22% of total herbage offered in the first full growth season (August 2014 to May 2015). This meant that at least 60% of the diet of these sheep was comprised of cocksfoot. In late spring/summer, the growth rate of cocksfoot-lupin pastures slowed to 20 kg DM/ha/day compared with 43 kg DM/ha/day for lucerne. Despite these differences in feed consumption and pasture composition, the feed conversion efficiency of sheep liveweight gain was the same for both pasture types and averaged 131 g of liveweight gain/kg of DM consumed from August 2014 to May 2015.

Mots clés : agronomy ; lupinus polyphyllus ; perennial lupin ; high country ; plant science ; Lupinus polyphyllus L. ; Russell lupin ; dryland ; high country pastures ; Medicago sativa L. ; Mackenzie Basin ; farming


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