Offering livestock dietary choice through access to different pasture species enables livestock to regulate their own feed intake, select for nutrients and minerals, balance rumen health and display natural grazing and foraging behaviours, which could in turn result in increased livestock productivity. An experiment was conducted at Hamilton, Victoria, Australia, to test the hypothesis that offering lambs dietary choice through spatially separated combinations of pasture species would improve lamb performance, relative to lambs with no dietary choice. The experiment tested seven treatments, replicated four times in a randomised complete block design with plot sizes of 1 ± 0.1 ha. The treatments were: 100% perennial ryegrass (Lolium perenne L.) (PR), 100% plantain (Plantago lanceolata L.) (PL), 100% lucerne (Medicago sativa L.) (LU), 50 : 50 perennial ryegrass/plantain (PR + PL), 50 : 50 perennial ryegrass/lucerne (PR + LU), 50 : 50 plantain/lucerne (PL + LU) and 33 : 33 : 33 perennial ryegrass/plantain/lucerne (PR + PL + LU). In the multiple species swards, the pasture species were separated spatially (by area). Plots were grazed by weaned lambs between March and June 2011. Pre-grazing herbage mass during March and April were highest (P < 0.05) from the lucerne and lowest (P < 0.05) from the plantain, with lucerne producing 4.5–5.5 t DM/ha during this time, whereas the perennial ryegrass and plantain produced 3.5–3.9 t DM/ha and 2.3–3.0 t DM/ha, respectively. Herbage disappearance (calculated estimate of feed intake) was highest (P < 0.05) from the lucerne and lowest (P < 0.05) from the plantain during March and April. Leaf crude protein between the perennial ryegrass and plantain did not differ (P > 0.05) and were lower (P < 0.05) than the lucerne, but the perennial ryegrass and plantain had higher (P < 0.05) leaf on offer (kg DM/ha). Plantain leaf had higher (P < 0.05) Fe, Zn, Co, Ca and S than the perennial ryegrass leaf and higher (P < 0.05) Se, Cu, Mg, Na and Cl than the perennial ryegrass and lucerne leaf and a more negative (P < 0.05) dietary cation : anion difference. The agronomic data presented in this paper provides support for the hypothesis, with lambs showing dietary preferences between pasture species and morphological components, and forms to basis for why these preferences exist. The two subsequent papers show how offering lambs dietary choice affected the performance of male lambs to slaughter and female lambs to first joining.

To cite this article: M. J. M. Hay , P. Nes & M. R. Robertson (1985) Effect of grazing management and season on nitrogen and phosphorus content of leaves and stolons of white clover in mixed swards, New Zealand Journal of Experimental Agriculture, 13:3, 209-214, DOI: 10.1080/03015521.1985 The nitrogen (N) and phosphorus (P) contents of leaf, surface stolon, and buried stolon of white clover (Trifolium repens L.) were measured in samples taken every 2 months, from pasture under rotational grazing by cattle (RGC) and set stocking by sheep (SSS), for 3 years. The effect of the system of grazing management of sheep on Nand P content of 3 herbage classes of white clover was examined during a I-year period by analysing samples taken monthly from pastures with 3 different management backgrounds; set stocked (SS), rotationally grazed (RS) or set stocked from lambing to drafting, then rotationally grazed for the rest of the year (CS). In the 3-year study, the content of N did not differ between the RGC and SSS treatments but the mean values of 4.59% in leaf, 2.75% in surface stolon, and 2.22% in buried stolon all differed. However, P contents differed between treatments: with RGC treatment, mean P levels decreased (0.43, 0.29, and 0.23% for leaf, surface stolon, and buried stolon respectively) whereas, with SSS treatment, contents in each of the respective herbage classes were higher and differences among the herbage classes were much smaller, the only significant difference occurring with buried stolon (0.51,0.51, and 0.47% for leaf, surface stolon, and buried stolon respectively). The system of sheep grazing management affected both Nand P contents in the same manner, with contents decreasing in the order SS > CS > RS. Again, there was a marked decrease in mean N content of the herbage classes in the order leaf (4.35%), surface stolon (2.97%), and buried stolon (2.11%), whereas the mean P contents of the herbage classes differed Received 21 March 1985. revision 10 May 1985 much less, with buried stolon (0.43%) being lower than leaf and surface stolon (both 0.51%). Seasonal variation in both Nand P content of each of the herbage classes in both studies followed the same trend -higher values during the moist, cooler part of the year (May-September) and lower values during the drier, warmer period (January-March).

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Ewe nutrition during pregnancy and lactation is a key determinant of ewe and lamb performance. A paddock-scale field experiment in western Victoria, Australia, tested the hypothesis that grazing maiden ewes on plantain (Plantago lanceolata L.) from mid-pregnancy until lamb weaning (July 2010–January 2011) would increase ewe liveweight and condition score during this period, reduce worm egg counts, and increase lamb liveweights at birth, marking and weaning, relative to tetraploid perennial ryegrass (Lolium perenne L.), but that further increases would be achieved by offering a spatially arranged sward of plantain and perennial ryegrass. The experiment tested three treatments: plantain (PL), perennial ryegrass (PR), and a 50 : 50 (by area) spatially separated mixture of perennial ryegrass and plantain (PR + PL). Plots were ~1 ha in size arranged in a randomised complete block design with four replications. The ewes were Coopworth composites joined at 8 months of age. Feed-on-offer levels (kg DM/ha) did not differ (P > 0.05) between treatments, with 2.3–3.0 t DM/ha being available pre-grazing. Twin-bearing ewes had higher (P < 0.05) liveweights when offered PR + PL compared with PR or PL at late-pregnancy and higher (P < 0.05) liveweights than PR but not PL (P > 0.05) at lamb marking. At weaning, single-born lambs were heavier (P < 0.05) on PR than PR + PL, with the PL being intermediate. There were no other significant differences (P > 0.05). This experiment has found that feeding plantain to ewes during pregnancy and lactation, or offering ewes spatially separated mixes of plantain and perennial ryegrass, offers no clear liveweight or worm egg count improvement for ewes and lambs relative to a tetraploid perennial ryegrass under Western Victorian conditions.

The uptake of potassium from hydroponic solutions by Trifolium repens is reduced in the presence of NH 4 + . However, it appears that a concurrent effect of NH 4 + is to induce, via the plant, marked changes in pH which counters the effect of NH 4 + on K uptake. When the variation in measured mean K concentration changes (KCC) associated with the variation in pH change is removed by analysis of the data using pH as a covariate, an apparent increase in K removal from solution is observed in the presence of NH 4 + . Plant-induced changes in pH also apparently affect the Al-NH 4 + interaction. This treatment combination induces a plant effect on the pH which in turn keeps the KCC at a fairly constant level resulting in no apparent interaction. However covariate analysis reveals the marked effect Al has on K uptake at the zero NH 4 + level. Al in the nutrient media at 148 uM causes an apparent K efflux which can not be 1635