Animal Performance and Nutrition on Kikuyu
Animal Performance and Nutrition on Kikuyu
Early research
Jim Lambert, DSIR Kaikohe, began to quantify the growth and feed value of kikuyu grass to farmers in the 1960’s. Kikuyu grass grew well in summer in comparison to other pasture grasses, and persisted much longer in periods of low rainfall. He set up trials to establish the seasonal yields of grass species, namely Grasslands Ruanui, Manawa and Ariki ryegrasses, Grasslands Apanui cocksfoot, paspalum, kikuyu and a Welsh tall fescue. The paspalum came from Australia and the kikuyu from Northland roadsides.
He sowed plots on two types of soils, an alluvial Wairoro clay loam, and a volcanic Waiotu friable clay. Plots were both mowed and grazed rotationally with dry sheep.
The kikuyu pastures on Wairoro soil yielded an average of 17,000 kgDM/ha/year (almost 15,000 pounds per acre) over four years, with peaks of production greater than any other grasses in summer and autumn. Other grasses yielded around 12,500 kgDM/ha.
On the better soils the kikuyu advantage was not as marked.
Lambert commented: ” Kikuyu pastures have been the highest producing pastures in Kaikohe trials. The evidence from these trials and from observations around Northland makes it obvious that detailed work should be done on the species. Because of this, a grazing trial has been established, to check on the value of this grass as a component of a mixed pasture. In addition, a programme of selection of an improved type has begun. At this stage, it is difficult to advise widespread use of kikuyu. Where kikuyu is already present, under most conditions, a high-producing pasture can be developed if the outlook is towards using it as a part of a species mixture instead of the sole grass.”
Graeme Piggot and two MAF colleagues, Garry Goold and Neil Percival, presented kikuyu grass pasture yield and growth pattern facts and figures to a forum in Whangarei in November 1985. Cutting trials of mixed swards with kikuyu grass had averaged yields of 12 tonnes DM/ha, with a range of 8 to 15 t DM/ha/yr. The lowest yields were associated with kikuyu grass dominance. Rates of growth are lowest in June and July, less than 10 kgDM/ha/day, and reach an October rate four times greater (40 kgDM/ha/day). Kikuyu-dominant pastures could either be higher or lower annual yielding than temperature pastures, depending on the summer conditions. They are lower in relatively cool, moist summers.
“On farms with a strongly spring-biased feed requirement, e.g. dairying or lamb production, or where soils are moist or cooler such as river flats or higher-altitude country, the presence of kikuyu grass in pastures is likely to reduce animal output.”
Kikuyu dominance
Pasture agronomist Garry Goold reported to the 14th International Grassland Conference in 1981 on the effect of sheep and cattle grazing on a mixed ryegrass/kikuyu grass/white clover pasture in Northland. He said winter and spring are critical seasons in most NZ pastoral farm systems and control of species dominance is essential in maximising yield from such a pasture mixture.
“Farmer experience suggests this control is not readily attained by normal grazing management practices,” he said. A five-year grazing experiment with two stocking levels (medium and high) of sheep and cattle was conducted at Dargaville from 1970 to 1975. The pastures were divided into 24 paddocks, allowing a six-paddock rotation of four treatment groups. Each group went through an 18-day rotation through the year and the animals were replaced in spring. They were one-year steers stocked at nine and six head/ha and wether sheep at 45 and 30/ha. Dry matter yields were estimated from two pasture frame cuts in each paddock and botanical composition of the pastures was assessed each spring by point analysis along permanently sited line transects in each paddock.
Major changes in the pastures occurred in the first year and continued thereafter. The ryegrass content of the spring pastures declined rapidly in the higher-stocked treatments and the pastures stocked with cattle. Annual poa came into the pastures in the third year and in the final (fifth) spring it made up half of the sward. Ryegrass and annual temperature grass contents of pastures are favoured by sheep grazing, while the white clover content is likely to be reduced. As the cattle pastures tended towards kikuyu grass and white clover, Goold suggested a later spring calving date. The higher stocking levels reduced annual dry matter yield by 25% and were well above average for the district and probably above optimal for animal performance. The invasion of poa in spring pastures was related to pugging, Goold thought.
Nutritive value
Kikuyu grass has higher fibre levels and lower protein, soluble sugar and organic matter digestibility in ruminants than temperate grasses like ryegrass (Jackson et al. 1996). A group of researchers from the Department of Animal Science, Massey University, and from AgResearch Grasslands, Palmerston North, have compared the nutritive value of subtropical grasses like kikuyu with the widely used standard, perennial ryegrass. Leaves from the kikuyu grass were harvested in mid-summer and subjected to chemical analysis for total nitrogen, condensed tannins, soluble sugar, total cell wall and organic matter digestibility (OMD), plus in vitro rumen incubations to measure the net conversion of plant nitrogen to ammonia. Kikuyu grass was found to have crude protein levels of 15% – 17.5% of total dry matter, versus 22% – 24% for ryegrass. Soluble sugar levels in kikuyu (4.3% – 6.6%) were only half those of ryegrass, and OMD of 65% – 69% (of total dry matter) compared with around 85% for ryegrass. Moreover kikuyu grown in Northland had lower values than kikuyu grown in Waikato and Manawatu. The lower OMD values for kikuyu would suggest lower voluntary feed intake by ruminant animals and the combination would be likely to reduce animal production, the researchers said.
Sheep feed value
Sheep and cattle grazing on kikuyu pastures during the summer months are not usually able to get enough nutritive value to maintain their body weights, and so they can lose weight amid apparent plenty.
In 1974, J.P.Joyce, a researcher at MAF Ruakura, examined the nutritive value of kikuyu grass as a feed for sheep in terms of the energy and nitrogen retentions. He had kikuyu-dominant pasture on the Dargaville Experimental Station cut with a flail harvester during late summer and early autumn of 1971-72. The short cut was grass 8-13 cm high and the long cut was three weeks later at 20-30 cm high. The cut grass was mixed with dry ice and transported to Ruakura, where it was quick frozen and stored. It was used as sole feed for each of four groups of sheep (six wether hoggets per group) and two groups were fed a standard pellet ration for comparison.
Nine sheep of the same mob (seven-month Perendale wethers) were slaughtered on the day before the start of the feeding trial to provide initial body composition data.
Three of the groups were fed ad lib with the thawed kikuyu grass and the other three at a level calculated to supply a maintenance energy ration. One group got the short cut, a second the long cut and the third the pellets. Total dry matter intakes were recorded, along with urinary outputs.
Nutritional components
Short cut kikuyu Long cut kikuyu Pellets
Crude protein 10.7% 16.9% 13.8%
Soluble sugars 4.03% 2.74% 8.27%
Crude fibre 33.0% 32.9% 20.7%
Ash 11.9% 9.8% 8.1%
Energy (kJ/g) 16.78 17.53 17.03
No significant differences were found between the two kikuyu diets in voluntary dry-matter intakes. Sheep fed the ad lib pellets ate the most, 37% more dry matter than either kikuyu diet. All groups on restricted feeding lost weight over the 72-day trial period but animals on the short-cut kikuyu feed lost the most. With ad lib feeding, only the pellet-fed sheep gained weight; those fed kikuyu lost weight, but at a lower rate than the restricted feed groups.
Growth rates
Ad lib Restricted
Short cut Long cut Pellets Short cut Long cut Pellets
LW change -50 ± 21 -40 ± 29 63 ± 29 -30 ± 30 -53 ± 20 -45 ± 16
(g/day)
Joyce said that animal performance in terms of liveweight gain and energy and nitrogen utilisation was poor for two diets of kikuyu grass. Although the crude protein content of kikuyu is higher than that of most other tropical grasses it is considerably below that of most temperate grassland species. He said dry matter and crude protein digestibilities of kikuyu tend to be lower than published values for white clover, lucerne and perennial ryegrass, but they are similar to those of grazed pastures in northern NZ in the summer. “The poor performance of sheep eating kikuyu grass in this trial could have been primarily a result of an inadequate metabolisable energy intake uncomplicated by a protein deficiency at those levels of animal performance,” Joyce said. There was an indication that the metabolisable energy from the kikuyu was used less efficiently for maintenance than that from the pellets. The sheep needed about 8,000 KJME/day for maintenance, but were getting only 6,000 from the kikuyu ad lib and 5,000 on the restricted diet.
Autumn control
John Rumball, officer-in-charge at DSIR Kaikohe set up further trials to compare sheep performance at very high stocking rates on ryegrass/white clover pasture (R) with those run on ryegrass/kikuyu grass/white clover (RK). There were three management periods:
Part 1: Rotary slashing of RK in the autumn and stocked at 17 ewes/ha for four years.
Part 2: No slashing, 19 ewes/ha for three years.
Part 3: No slashing, 21 ewes/ha and an extra 19 ewes/ha from February to April on the RK for four years.
The results showed little difference between R and RK in the part 1 management, with around 630 kg/ha of lamb and wool weight. At the slightly higher stocking rate (19 ewes/ha) and no slashing, there was again little difference between pastures in production of lamb and wool (720-740 kg/ha). At the very high stocking rates (40 ewes/ha Feb-Apr on RK) there was again no difference in production between pastures (about 700 kg/ha).
The trials demonstrated for the first time that control of kikuyu grass in the autumn is very important, either by slashing or by high autumn stocking rates. Both pastures gave similar annual production but there were seasonal differences. Lambs were lighter at weaning on kikuyu but caught up during the autumn. Ewes were also lighter at weaning but put on more weight in the autumn on kikuyu.
But while the animal production per hectare may be similar, ryegrass/kikuyu pasture probably return less income because of seasonality.
Gareth Baynham, AgFirst Northland has pointed out (2007) that Northland farms make the most money between June and December. The revenue in cents/kg dry matter is 25-35 cents in that period, but falls as low as 5 cents during the autumn when kikuyu makes up 80%-plus of the feed.
Nutritive value
Spring Autumn
Pasture type Kikuyu grass Ryegrass Kikuyu grass Ryegrass
LW gain (g/day) 80 114 48 117
DOM intake (g/day) 935 977 839 823
Nutritive value 8 .4 11.9 4.7 14.8
Keith Betteridge, DSIR Grasslands, (1979) followed up the Rumball trials and compared ryegrass/white clover (R) and ryegrass/kikuyu grass/white clover (RK) pastures under 35-40 kg LW sheep grazing in spring and autumn. In spring kikuyu was only 24% of the available pasture and in autumn 71%. The digestibility of the R pasture was higher in spring and autumn but the difference was very small. However in autumn the structural carbohydrate content of kikuyu was considerably higher than ryegrass and the soluble carbohydrate significantly lower. In spring there was no significant difference in nutritive value between the pasture types, but in autumn R had a nutritive value three times greater than RK. Nutritive value was liveweight gain over digestible organic matter intake (both in g/day) expressed as a percentage.
Feed intake was similar on both pastures (800-1,000 g digestible organic matter/day).
“It is clear that high sheep performance cannot be expected from kikuyu grass. However, if pastures containing kikuyu grass are well managed so that temperate grasses and legumes are encouraged, the nutritive value of the pasture will be improved. Good management involves hard grazing kikuyu grass in summer and autumn to prevent a mat building up and smothering other grasses and white clover. If this proves impossible then mechanical removal of herbage (silage, or slashing in late autumn) would be useful, but less effective than frequent hard grazing,” Betteridge said.
Intensive beef systems
MAF researchers Graeme Piggot and Hugh Morgan on the Dargaville Research Area between 1979 and 1985 ran three intensive beef systems on kikuyu grass pastures. Nine-month Angus steers were grazed in groups of four at a stocking rate of six to the hectare. They were run from June to the following April, 11 months. The grazing cycle was initially 28 days, followed by 14 days from late August to late December and 21 days to April. The grazing period was 3.5 days to late December and 7 days thereafter. The first year’s steers gained 179 kg LW average and the second year’s intake 151 kg.
The second part of the farmlet trials continued on with the second intake for six months at 4/ha stocking rate until slaughter weight in mid-October. The grazing cycle was 63 days to early August and 21 days thereafter, with a 3.5 day grazing period. The pastures were half kikuyu at the start and 5% at the finish. In six months 85 kg average live weight gain was achieved, to an average finish weight of 455 kg LW.
In the third part weaned Friesian bull calves were stocked at 6.3/ha from early November. They averaged 92 kg LW at the start and gained to 177 kg/head in March. The summers were dry and each calf got 1 kg of proprietary meal per day during February. Production was 270 kg/ha of LWG in five months.
Piggot and Morgan said that finishing beef to slaughter weights on kikuyu grass-based pastures is possible in 17-18 months for bulls and 24-26 months for steers. “The weight gains were similar to those from solely temperate pastures, accepting the relatively high stocking rates which are required on kikuyu grass pastures for the purposes of pasture management,” they said.
Dairy production
Measurements have shown that kikuyu-dominant pasture can produce as much as 20 tonnes dry matter (DM) annually, and typically between 10 and 16 tonnes, although total dry matter is a poor measure of kikuyu productivity. This is because a small variation in cutting height will result in a large variation in DM yield; the ratio of leaf to stolon changes during the growing season (affecting grazing preference, utilisation, ease of harvest and nutritive value) and lower estimated metabolisable energy (ME), lower digestibility and soluble sugars and higher fibre content when compared with ryegrass pasture without kikuyu grass.
MAF researcher Graeme Piggot established that milkfat production from kikuyu grass-based pasture for one season was similar to milkfat production on two farms with temperate pastures.
“The annual yields of kikuyu grass versus temperate pastures differed little except for lower growth rates in winter. Grazing management was adjusted to account for this difference, and ultimately the efficiency of milkfat production was similar between farms,” he said. The kikuyu grass-based farm was on the coast west of Dargaville, on a sandy loam. The herd on the kikuyu grass farm began calving in mid-July and milked through to mid-May. Over the June to June year the pasture yield from cages was similar on kikuyu and temperate farms at about 14.5 tonnes DM/ha and the per cow milkfat production was similar (144 kg MF/cow on kikuyu versus 147 on the temperate pastures farm). An allowance had to be made for the difference caused by the yearling heifers grazing the kikuyu grass farm and for the effects of flooding during Cyclone Bola (1988) on the temperate pastures farm. The kikuyu produced 330 kg MF/ha compared with 374, but the efficiency of milkfat production was very similar – 37 kg DM/kg MF on kikuyu versus 36.
“The purpose of presenting this data was not principally to allow strict comparisons between dairying on pastures with or without kikuyu grass. It was to show, as has been shown with the beef and sheep production research, that the presence of kikuyu grass may not be an important factor in explaining dairy farm production differences,” Piggot said.
Whangarei Heads dairy farmer Murray Jagger, the founding chairman of the Northland Kikuyu Action Group, and LIC FarmWise consultant Wayne Andrewes collaborated on a in-depth study of kikuyu pasture suitability for dairying. Their findings were presented to the 51st meeting of dairy farmers at Massey University in 1999, in a paper called Kikuyu Management for Milk in the New Millennium. They said that a kikuyu farm in coastal districts can produce over 730 kg milk solids (MS) per hectare in dry conditions. “With split calving and a good balance of temperate grasses and white clover, high milk solids production can be obtained from kikuyu pasture; 1,000 kgMS/ha on dry land, and 1,200 kgMS/ha with irrigation.”
It makes a significant contribution in summer and autumn, but feed quality can decline rapidly and winter and spring pasture growth can be seriously reduced by kikuyu dominance. Kikuyu is more tolerant of floods, drought, fungal and insect attack than ryegrass.
Milk production from a kikuyu farm in Northland may be as much as 20% above or below that of a ryegrass farm in the same district. Production will be low when kikuyu is allowed to remain dominant in the autumn, where there is little advantage to kikuyu because the farm is in a wetter or cooler area. Kikuyu does offer advantages in coastal areas. July calving at Whangarei heads produced 737 kg MS/ha from kikuyu pasture with only 926 mm of rainfall, when evapotranspiration exceeded 950 mm. Research inland in a cooler, wetter environment at Kaikohe indicated that later calving on a kikuyu pasture would enable better feeding at a high stocking rate and that split calving (60% spring, 40% autumn) was another option to control and utilise the growth pattern of kikuyu. Split calving on kikuyu pastures on the Dargaville Demonstration Farm has produced around 1,000 kgMS/ha on dry land. An irrigated kikuyu dairy farm near Kaitaia has produced 1,200 kgMS/ha, milking extra cows in autumn. (source? David Grey or George McMonagle)
Case Study: Milk solids production from kikuyu-dominant pasture
M & H Jagger Whangarei Heads 90 % Kikuyu dominant
Notes: Whangarei District average ranged from 550 to 614 kgMS/ha during these seasons. All kikuyu mulched twice or three times a year. Annuals sown in April.
Jerseys cows calving early July. Young stock grazing off.
Fertiliser 100-120 kg N/ha.
Supplements fed: 15 t molasses in 1996/97, up to 55 t in 04/05, feeds baleage.
Contour: 60 % rolling hills Rangiuru clay; 40 % flat Ruakaka loamy peat.
Key Point: All the tractorable land on this farm is mulched and sown with annuals in April each year.
Season Kg MS Cows ha Kg MS/ha
04/05 118,000 450 160 738 Mulch + annuals
03/04 109,540 437 150 730 Mulch + annuals
02/03 105,080 437 150 700 Mulch + annuals
01/02 97,100 400 150 647 Mulch + annuals
00/01 115,920 380 150 773 Mulch + annuals
99/00 104,350 370 150 696 Mulch + annuals
98/99 Leased 53 ha of low fertility rank kikuyu.
96/97 84,800 270 97 874 Mulch + annuals
Maximum improvement 227 kg MS/ha
N.B. Assuming that the original 97 ha was producing around 860 kgMS/ha in 2001/02, the contribution from the 53 ha of leased kikuyu land was initially only 250 kgMS/ha, in order to average 647 kg MS/ha over the whole 150 ha.
Profile: Murray Jagger
Murray Jagger runs 520 winter-calving Jerseys on 200ha near Whangarei Heads which is completely kikuyu dominant. Production is around 850kg/ha milk solids. He aims to renovate one third of the farm each year, by direct drilling annual ryegrass into sprayed and mulched kikuyu. On the lighter coastal country pasture revert to kikuyu in three years.
His first mulcher was a converted Gallagher silage harvester with the chute taken off the top and replaced with a timber top. However it chopped rather than cut.
Trimax in the Bay of Plenty were first to market with a true drum and flail mulcher, used to chew up kiwifruit vine cuttings.
Then a first of what has become a flood of Italian mulching mowers appeared in Northland for kikuyu renovation. Murray now uses a Berti machine with a 114hp Claas tractor which has a 2.2m cutting width. He has a personal preference for hammer flails.
Murray believes the Kikuyu Action Group is a marvellous example of farmer-led trials and development of the “toolbox” approach to kikuyu management.
Circumstances and conditions can be different in farming districts, he said.
Farmers are encouraged to take what they need out of the “toolbox”, such as controlled grazing, chemical topping, knockout spraying, oversowing, undersowing, direct drilling, mowing and mulching.
On stepping down from the KAG chair, but remaining on the committee, Murray Jagger said it never ceased to amaze him the interest from farmers in the research work the group does.
“I have enjoyed totally my involvement with this group and feel quite proud of what we have achieved and the interest we have created in the quest for improved productivity from kikuyu pastures.”
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