Maximising animal production through increased intake of high quality forage is an important aim of pasture renewal. Traditionally, high quality forage has been produced from pasturemixtures of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens). Plantain (Plantago lanceolata) and other herb and legume species have also been added to pasturemixtures in an attempt to improve pasture production and quality. However, the question is which species to include in a pasture mixture? To help answer this question, information is needed about how different species contribute to pasture function (e.g., herbage yield, lamb liveweight gain, weed suppression and nutrient leaching).
quantifying species identity and diversity effects from pasturemixtures. The plots were sown containing one- to four-species, based on a simplex mixture design containing all possible combinations. The annual and seasonal DM production were statistically analysed with a special cubic model created from the simplex mixture design, enabling predictions to be made on the mixture that would produce maximum yield for the second year of growth (May 2016 to May 2017). The DM production and botanical composition of each monoculture and mixture were measured, compared and analysed. To explain differences in yield between mixtures, N content, leaf area index and light interception were also measured. The modelled analysis showed that five two-species mixtures and one three-species mixture showed significant species interactions and subsequent yield increases over the mean of their component monocultures. The seed mix that was predicted to maximise yield consisted of 0.29 ryegrass, 0.20 plantain and 0.51 red clover in terms of seeds/unit area, predicted to yield 16.44 t DM/ha for the second year of growth. This mix produced 5.19 t DM/ha more than the rygrass and white clover (RG*WC) mixture, which yielded 11.25 t DM/ha. The greatest diversity effects were shown by the two species mixtures that included red clover, and produced 4.93 t DM/ha (RG*RC) and 5.31 t DM/ha (P*RC) above the mean yield of the monocultures.
There are relatively few studies revise on intensive grazing management with irrigation, improved grasslands of the effect of pasture diversity on herbage DM yield and nutritive value, Daly et al. (1996) showed a multi-species pasture mixture of erect legumes (red clover and lucerne), herbs (chicory and plantain) and grasses (e.g. tall fescue, prairie grass, cocksfoot) out- yielded a perennial ryegrass-white clover pasture in a dryland pasture in Canterbury. In further New Zealand work, Goh and Bruce (2005) showed a multi-species mixture consisting of herbs, legumes and grasses had greater herbage DM production and legume content than a perennial ryegrass/white clover pasture under border dyke irrigation in Canterbury. In United States work, Skinner et al. (2006) reported greater herbage DM production and nutritive value of a five species mixture containing chicory, meadow fescue (Festuca pratensis Huds.), perennial ryegrass, cocksfoot (Dactylis glomerata), white clover than a simple perennial ryegrass/white clover pasture under three water regimes with the greatest difference when a summer water stress period was included treatment. The mixture not only extracted more water from deeper in the soil profile but also increased water remaining in the top 30 cm. Further work is needed to ascertain how pasturemixtures containing legumes and herbs can improve the herbage DM production and nutritive value in the moderate-high fertility, irrigated environments of dairy systems.
top of the sward which would be grazed earlier in the grazing bout. The establishment of Italian ryegrass did not seem to affect the proportion of white clover in either MIX or PRG pastures, but it did reduce (remove) lucerne from the MIX+I pasture resulting in a greater legume content in the MIX versus the MIX+I treatments. However, due to the low Italian ryegrass content in the MIX+I and the more uniform vertical distribution of leaf on lucerne compared with clover in the MIX, we suggest this avoided any potential diurnal variation in N intake between the two treatments. Thus, if the change in species composition of a pasture mixture alters the rate of ingestion of dietary protein (as likely occurred for PRG and PRG+I), then it is likely to achieve diurnal variation in urinary N excretion. Further, if the addition of another plant species doesn’t alter crude protein content of the herbage or apparent N intake (which, in this case, it did not) then it is unlikely to alter total urinary N excretion. The advantage of using pasturemixtures to shift diurnal urination patterns presents an opportunity for farmers, which have stand-off facilities, to remove cows from pasture during periods of high risk urine N loading. The N in effluent can then be captured from those stand-off areas and applied to pastures at a rate which plants can utilize for growth (ie <100 kg N/ha), reducing the proportion of N leached compared with that of N deposited as urine on pasture (>600 kg N/ha).
Above and below ground resources that improve the success of weed invasion include light availability the amount of available soil N. The Frankow-Lindberg (2012) trial found that the proportion of weeds in the harvested biomass was affected by both factors, it was negatively correlated with nitrogen uptake and positively correlated with light penetration. However the number of weed species was positively correlated with light penetration but nitrogen uptake had no effect on weed species number. As expected low density pasture swards were more open than high density swards. They also found that the two legumes in the trial (red clover and lucerne) captured most of the available light, with little difference between the two legumes. There were also little differences between the light penetration of timothy, perennial ryegrass and chicory. Mixtures tended to have more even resource use over time, the mixed pasture swards had more closure in their canopies, taking up more light and they took up more of the available N from the soil than monocultures. Hence, explaining why the pasturemixtures had a lower number of invading species producing less biomass than all the pure swards.
9 ryegrass white clover pastures. The chicory, plantain, white clover and red clover pasture produced 70 g/d higher live weight gain compared to the perennial ryegrass-white clover pasture. Somasiri et al. (2015b) investigated the influence of three different pasturemixtures on the live weight gain of weaned lambs. The standard reference pasture contained perennial ryegrass and white clover, the plantain mix contained plantain, white clover and red clover while the chicory mix contained chicory, plantain, white clover and red clover. Lamb live weight gain was highest when grazing the chicory pasture at 44.5 g/d higher than the pasture mixture. However, the plantain mixture did not show significant differences in lamb growth rate compared to a chicory pasture. Therefore, Somasiri et al. (2015b) concluded that either the plantain or chicory mix would be superior to the standard perennial ryegrass-white clover pastures to boost lamb live weight gain. In order to get test the benefit of these mixtures, it would be worthwhile to evaluate these pasturemixtures in temperate regions elsewhere in New Zealand and the world. Lastly, Golding et al. (2011) compared an old pasture, a new pasture (tetraploid perennial ryegrass and white clover), a plantain pasture (tetraploid perennial ryegrass, plantain and white clover) and a herb clover pasture (plantain, white clover, red clover). Animal live weight gains did not differ between the new and old pastures. However, the herb clover pasture had a 128 g/d higher live weight gain than that of the pasturemixtures while the plantain pasture supported less live weight gain than the new and old pastures. The lack of difference among the new, old and plantain pasture was attributed by Golding et al. (2011) to the plantain being selectively grazed against in the autumn period as it became unpalatable. Therefore, the higher production from the herb clover pasture is likely to be a response to the clovers being grazed in the autumn and their higher nutritive value.
White clover is the most important forage legume in New Zealand. It is sown widely in New Zealand and is a vital component in many pasturemixtures. White clover is a perennial and has a prostate growth habit with stolons. Stolons root from the nodes and produce plants that become independent of the original plant (White & Hodgson 2000). Leaves are trifoliate with oval leaflets. White clover performs well on moderate to high fertility soils. White clover can be less productive in summer in dry periods due to its limited root system, for this reason persistence can be poor when rainfall is under 600-700 mm (White & Hodgson 2000). Moot et al. (2000) estimated an average base temperature for vegetative development of white clover from a number of cultivars to be 0.8 ± 0.28 ºC (Table 2.1). Thermal time required for germination was estimated at 41 ± 1.6 ºCd. White clover stops growing at approximately 8-9 ºC and reaches maximum growth rates at 25 ºC, which is why the winter growth of white clover is poor (White & Hodgson 2000).
The objective of this study was to assess the effect of diverse pasturemixtures and grazing management on profitability of Canterbury dairy farms using a commercial modelling tool, Farmax Dairy Pro. Two years of pasture growth and quality data were obtained from irrigated plots sown with a pasture mixture consisting of perennial ryegrass, white clover, red clover, chicory and plantain (diverse) or the same pasture mixture plus Italian ryegrass (diverse-Italian). Pastures were subjected to one of three grazing management regimes: (1) conventional grazing (grazed to a compressed height of 3.5 cm all year); (2) spring lenient grazing; and (3) autumn lenient grazing. The data were fitted to a base model farm (average of North Canterbury region) using Farmax Dairy Pro to produce six different farm scenarios. Farm scenarios were ranked and compared by profit expressed as earnings before tax. Pastures managed by autumn lenient grazing resulted in the lowest DM production, more supplement purchased, and hence, lowest profit compared with conventional or spring lenient grazing management. The diverse pasture managed by spring lenient grazing resulted in the greatest profit ($2,658/ha) compared with other scenarios (average $2,261/ha). This greater profit was driven by greater annual DM production per hectare and, hence, less supplement purchased. When diverse pasture is considered, spring lenient grazing is a potential management option for irrigated Canterbury dairy farm systems to increase DM production and thereby profitability.
population and therefore increasing leaf area for light interception (Korte, et al., 1982; Michell, et al., 1987; Xia, et al., 1990). Whereas grazing to high residuals can increase pasture allowance and subsequently increase energy intake and therefore milk production (Curran, et al., 2010; Ganche et al., 2013). By using higher post grazing pasture residuals there is the potential for increased milk production, but there could be a long term effect on pasture quality (Roca-Fernandez, et al., 2012). Grazing to low pasture residuals has the potential to increase pasture quality through increasing clover content and reducing dead matter and stem material (Kelly, et al., 2005; Phelan, et al., 2013). This has subsequently meant that nutritive value of the herbage is improved due to increased crude protein, water soluble carbohydrates, dry matter digestibility and metabolisable energy (Curran, et al., 2010; O'Donovan, et al., 2004; Roca-Fernandez, et al., 2012). Pasture allowance plays an important role on residuals as a low pasture allowance results in lower post-grazing residuals than a higher pasture allowance. The trade-off is that low allowance and grazing to low levels reduces dry matter intake (Curran, et al., 2010; Macdonald, et al., 2008). Milk production is influenced by dry matter intake, this has meant that under low grazing residuals milk production per cow has been reduced (Delaby, et al., 2003; Ganche, et al., 2013). In the current farming climate many farmers use high stocking rates,
There is an economic incentive to breed and foal mares early in the season within the New Zealand commercial Thoroughbred production industry. This has caused disparity between the natural and commercially imposed breeding season, and possibly, the period of peak pasture energy availability and the mare energy requirements. A deterministic model was developed to model the energy balance, energy intake and energy requirement of Thoroughbred mares managed at pasture under commercial conditions to assess their energy status. The response of energy intake and energy balance to changes in five variables were tested. The variables tested were dry matter intake, bodyweight, foaling date, pasture metabolisable energy, and energy requirement. For all foaling dates modelled, the mare was in energy surplus during pregnancy. Onset of lactation created a rapid and significant decrease in mare energy balance. Delay in foaling increased the magnitude of the post-partum energy deficit, and later foaling mares experienced a prolonged decrease in post-partum energy balance. The size of the deficit would, theoretically, decrease 1 body condition score, decrease circulating leptin concentration and initiate lean body mass mobilization which was previously found to negatively impact reproductive performance in the mares. The duration and size of the post-partum energy deficit could be reduced by shifting foaling date closer to the beginning of breeding season (1 st September), thus synchronizing period of peak pasture energy with the mare’s
In both timothy and meadow fescue the primary tillers switch to the generative growth phase in early May and soon after that the apex is elevated as stem formation begins. The switch is strongly related to the temperature sum (base T = 0°C). The elevation rate of the apex in primary tillers is a maximum of 25 - 30 mm per day during the most rapid development. The axillary tillers start to elongate a little later. Timothy needs only a single long day induction for flowering, whereas most temperate, perennial grass species need short days or low temperature for primary induction and then long days for secondary induction (Heide 1994). Therefore also the axillary tillers of timothy may have floral induction under long day conditions. It seems to be a common phenomenon that a part of vegetative tillers of timothy start to elongate and produce nodes before the apex has switched to the generative stage. Due to both of these phenomena, a high proportion of timothy tillers have stem formation in the early part of the summer (0 - 0.5, Bonesmo 1999; 0 – 0.82, Virkajärvi et al. 2003; 0.44 – 0.65; Virkajärvi 2003). This is one reason for the very pronounced peak in DM production of timothy in mid-June, 120 – 180 kg DM ha -1 d -1 (measured in a grazing simulation of 4 week cycles). In contrast, the production is very variable in July (30 – 100 kg DM ha -1 d -1 ) and falls under 50 kg DM ha -1 d -1 in mid-August. These conditions must be taken into account in pasture allocation.
• Nitrogen fixation by pasture legumes is vital to the dryland pasture system. Conservative estimates of the amount of nitrogen (N) fixed by clovers in grass/clover pastures show that 25 kg of N is fixed for every ton of clover DM grown. If the contribution of the clover roots is included then it is probable that the clovers contribute 45 kg N/t clover herbage DM grown. Hence all farmers who prefer to avoid N fertilisers should rejoice at the sight of their legume dominant pastures!
Pasture species used 1D New Zealand are recognised as ditter1ng in their ettects on animal production, these differences being loosely attributed to Yariation 1n�asture quality". It the level ot oatput ot saleable product la the accepted measure ot pasture quality, thea the principal factors governing this are the quantity ot teed consumed and its subsequent ut111aat1on.