Kenya white clover shows promise for dairy pastures in warm climates

Why a new legume mattered for subtropical dairying#

By the mid-1970s, dairy farmers working in the wet subtropics of Australia had long leaned on white clover (Trifolium repens) to lift the protein and energy value of grass-based pastures. The problem was that ordinary white clover tends to falter once the weather warms, leaving grasses such as Paspalum dilatatum or Rhodes grass (Chloris gayana) to dominate through summer and autumn, a stretch when their feeding value is typically poor.

Kenya white clover (Trifolium semipilosum var. glabrescens) had already drawn interest in wet subtropical and elevated tropical districts of Australia, particularly in country where ordinary white clover had naturalised. Earlier laboratory work and early beef production trials, referenced in the paper, pointed toward a high nutritive value for the plant, and one cultivar, named Safari, had recently become available. What remained untested was how the legume performed under an actual milking herd, and that gap is what this study, described in the ASAP Conference Proceedings collection, set out to close.

Pasture improvement work of this kind sat within a broader program of tropical grazing research being run through the same organisation during this period, aiming to lift milk output from pastures across warm, humid parts of eastern Australia where temperate legumes often struggled to persist. Finding a legume that could keep contributing feed value through the hotter months, rather than just in spring, was therefore seen as a meaningful practical gain for dairy farmers in these districts.

How the Kenya white clover trial for dairy cows was run#

The work took place at the CSIRO Pasture Research Station at Samford, Queensland, on alluvial soils receiving a mean annual rainfall of 1030 mm. Three pasture types were compared: Kenya white clover cv. Safari grown with Paspalum dilatatum, white clover cv. Ladino grown with Paspalum dilatatum, and Rhodes grass cv. Pioneer grown alone with monthly applications of nitrogen fertiliser, except during May, June and July. The two clover-grass combinations were established as five replicate plots of 0.15 ha each, arranged in randomised blocks from April 1972, while the Rhodes grass occupied five paddocks that had already been established since 1967.

Jersey cows between their fourth and twelfth week of lactation were sorted into groups matched for stage of lactation, milk yield and liveweight, then rotated through the three pastures using a 3 x 3 Latin square arrangement, a design that lets every group of cows experience every treatment in turn. Feed was kept plentiful throughout the trial, with at least 40 kg of green feed available to each cow every day. Each run lasted 14 days: several days of settling the cows onto the new pasture, then a further stretch during which milk output was actually recorded.

Three separate seasonal trials were conducted: spring (August, September 1972) involving 18 cows, summer (January, February 1974) involving 12 cows, and autumn (March, April 1974) involving 9 cows. The long break between the spring and summer measurements happened because rugose leaf curl virus damaged the newly sown Kenya white clover in 1973, and the stand needed time to recover before testing resumed. Excess herbage during grazing periods was removed by animals outside the experiment, keeping the comparison focused on what the recorded cows actually grazed. The study sits alongside other grazing work by the same author, including an earlier paper on stocking rate and energy supplementation effects on milk production.

What the pastures themselves looked like#

During spring, both legumes made up a substantial share of the pasture on offer, with Kenya white clover contributing 54.8 percent and white clover 57.6 percent. From there the two species parted ways sharply. White clover's presence fell away quickly over summer and had become minor by autumn, whereas Kenya white clover kept delivering useful growth right through both of the warmer seasons.

Digestibility, measured using a laboratory in vitro method, was high for both legumes, running at 70 percent or above, with nitrogen content exceeding 3 percent in each case. Kenya white clover was somewhat less digestible than ordinary white clover across the seasons tested, and its own digestibility was lower in spring than later in the year. Rhodes grass and Paspalum dilatatum, in contrast, showed low digestibility that stayed roughly similar to one another throughout. Mineral levels across all pasture types were judged sufficient for production and changed little with season, though Kenya white clover carried a notably low sodium content.

These sward composition figures matter because they explain the pattern seen later in milk output: wherever a legume kept a strong foothold in the pasture, cow performance tended to follow, while swards that reverted to grass alone saw performance slip toward the levels recorded on straight Rhodes grass. Pasture samples were cut from small quadrats before and after grazing in each period, then separated into grass and legume fractions before being analysed, giving a direct measure of how much each species contributed to the sward at the time cows were actually grazing it.

Milk yield and composition across the seasons#

In spring, when both legumes were plentiful, cows grazing the Kenya white clover and white clover pastures produced more milk than cows on Rhodes grass, and their milk also showed richer fat, solids, protein and casein levels than milk from the grass-only pasture. Jersey cows on both legume pastures reached a matching yield of 15.9 kg per cow per day during that season.

The pattern shifted once white clover's growth dropped away in summer and autumn. Milk output from cows on white clover pasture fell to levels close to those recorded on Rhodes grass, mirroring the collapse in available legume. Cows grazing Kenya white clover, which still offered plenty of legume to eat, continued to give milk with a higher solids-not-fat content than the other two treatments during these later seasons.

Bloat turned up as a minor complication in spring: two mild cases occurred among cows on Kenya white clover and one among cows on white clover. Every affected animal recovered after treatment with anti-bloat oil, so the episodes were managed without any lasting effect on the trial's outcome. No such cases are reported for the summer or autumn evaluations, by which time white clover had largely disappeared from its pasture and legume intake overall may have been lower.

Weighing how much the evidence can tell us#

The Latin square design, rotating cows through all three pastures, is a reasonable way to separate pasture effects from differences between individual animals, and feed was kept non-limiting so pasture quality rather than pasture scarcity drove the comparison. Even so, the work was confined to one site across three seasons within a single year, cow numbers fell as low as nine during the autumn stage, and the Kenya white clover stand had only just recovered from a virus setback before the summer and autumn measurements were taken. We would treat the spring finding, where the two legumes performed almost identically, as reasonably solid, but the apparent summer and autumn advantage for Kenya white clover rests on fewer animals and a single growing season, so it reads more as an encouraging early signal than as a settled result across years and districts.

The authors trace the poor milk composition recorded on Rhodes grass and on Paspalum dilatatum pastures with little legume to low intake of digestible energy rather than to any shortage of protein, drawing on earlier research they cite showing that energy intake, not protein content, usually limits milk output from tropical pastures. Read this way, the main benefit both clovers delivered was lifting the energy value of what cows could actually eat, with Kenya white clover's advantage in summer and autumn coming simply from having more digestible legume present once the companion grasses had already lost condition.

Practical considerations for growing Kenya white clover#

Two practical drawbacks stood out. The first was the early setback caused by rugose leaf curl virus during establishment, though the paper notes that once the Kenya white clover pasture had recovered, it was not reinfected afterwards. The second was the plant's low sodium content, a trait noted in earlier analyses referenced by the author, although sodium levels measured in this particular study were higher than those previous reports had suggested, and the author judges that a deficiency is unlikely so long as the companion grass supplies adequate sodium of its own.

Combined with the stronger herbage yields and carrying capacities reported elsewhere for Kenya white clover pastures, the paper's author sees real potential for the species in wet subtropical dairy systems, particularly as a way of stretching high-quality legume feed through summer and autumn when white clover usually declines. For farmers and advisers working in similar climates, the practical appeal lies less in any large edge over white clover during spring, when the two performed alike, than in the extra months of useful legume growth that Kenya white clover offered once conditions turned warm.

The trial forms part of a wider body of pasture and grazing research from this author held in the Australian Society of Animal Production collection, alongside separate work on modelling pasture and animal systems that touches on related questions of pasture utilisation and animal response. Together these studies point to a consistent theme in the author's work: that the quality and persistence of the legume component, more than the grass itself, tends to set the ceiling on milk production from tropical and subtropical pastures.

Sources and further reading#

• Australian Association of Animal Sciences: successor to ASAP
• Trove library search: find a library that holds the paper
• Meat & Livestock Australia: red meat industry research and marketing body
• Feedipedia animal feed database: an open-access database of animal feeds

Questions#

— The Livestock Library team