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Chapter 10
Forage utilisation
L.R. Humphreys


Objectives for forage utilisation
The response of the pasture to cutting or grazing
The delivery of nutrients from the forage
Adjusting animal demand and forage supply
Providing continuity of forage supply
Conclusion
References


Objectives for forage utilisation

The increased forage production resulting from the strategies outlined in the previous chapter creates a potential for increased dairy output. The way the pastures are managed decides whether the effort and resources invested in improving the feed supply bring returns in the form of better milk output and the raising of more young stock. The principal objectives of forage utilisation (Humphreys 1991) are to:

The response of the pasture to cutting or grazing

The way pastures are cut or grazed powerfully influences the amount of growth and the persistence of the sward. There are three main ideas(Humphreys 1997).

Firstly, when growing conditions are good, the pasture yield is decided by whether there is enough leaf surface there to intercept the sunlight. It follows that if the number of the animals grazing the pasture is not excessive, so that a leafy sward which covers the ground is maintained, pasture yields will be high, and soil erosion (Humphreys, 1994) will be minimal. Similarly if pastures are cut infrequently or at a height which allows some leaves and buds to stay below cutting height, more sunlight is trapped and yields are high. Thus in Sri Lanka, Goonewardena et al (1984) found that if Panicum maximum was cut every 10 days the yield was 8.3 t/ha, and 15.5 t/ha if the cutting interval were increased to 30 days. Similarly cutting at five centimetres height gave 9.4 t/ha whilst cutting at 15 cm height increased the yield to 13.5 t/ha.

Another illustration comes from Ibadan, Nigeria (Figure 10.1). Leucaena leucocephala was grown in rows with varying space between them. Increasing the interval between cuts from six to 12 weeks when the shrub was grown close together at 0.5 m interrow spacing raised the dry-matter yield from 17 t/ha to the very high yield of 38 t/ha. The decrease in yield associated with wide row spacing lessened beyond 1.5 m due to greater compensatory growth and survival of individual plants at the two-meter spacing.

When L. leucocephala is grown to produce a fodder bank for the dry season the cutting height will influence how much fodder accumulates. When the shrub was grown at Samford, southeast Queensland and cut at 30 cm height in February, the peak accumulation of edible dry matter was only 2.4 t/ha; this increased to 4.2 t/ha if cut at 120 cm (Figure 10.2).

Second, the amount of pasture material which senesces increases as the rate of pasture growth exceeds the rate of removal by grazing or cutting. Senescent forage is most evident when plants experience drought or cold; it is not always understood that the rate of plant senescence is fastest when the rate of pasture growth is highest. Under-using the pasture therefore wastes a good deal of material which is eventually rejected by animals and adds to soil litter. The leafiness of the pasture also decreases with age, which reduces the nutritive value of forage. It needs to be emphasised that the first objective of pasture management is to maximise the delivery of nutrients used by the animal and NOT to maximise pasture growth.

The greatest yield of utilised forage occurs at levels of grazing or cutting which offer young grass to stock; the deterioration in quality with age of material is less for legumes than for grasses.

Thirdly, lenient grazing or cutting management will favour the persistence of erect growing grasses such as P. maximum. Pastures of P. maximum that are cut or grazed too intensively are short-lived, become invaded by weeds such as Pennisetum polystachion and require frequent replanting. On the other hand creeping plants, such as Arachis pintoi, are favoured by quite heavy grazing, since they maintain a high density of buds close to the soil surface and their leaves are less shaded by tall companion species if the pastures are well grazed.

The delivery of nutrients from the forage

The targeted nutritive value influences the decisions a farmer makes about how frequently the pasture might be cut. Frequent cutting gives young, leafy forage of high nutritive value and lower yield; infrequent cutting gives more stemmy forage with lower quality leaf material and higher yield.

Much depends upon the relative price of cut forage and concentrates. Cut forage may bring US 1.5c/kg in Indonesia (Soewardi 1986) or US 2c/kg in Thailand (Lekchom et al 1989) where concentrates cost about 16.5c/kg. As concentrates become more expensive a greater premium for forage quality should apply. Operators who cut forage from roadsides and waste lands for sale to dairy farmers will usually seek to maximise the yield and the ease of cutting.

The speed at which the pasture grows influences its nutritive value and the attainment of a yield worth cutting. Thus in the mid-country region of Sri Lanka, Chadhokar (1983) recommended cutting P. maximum every four to six weeks in the wet season and six to eight weeks in the dry season. At Muaklek in Thailand fertilised grasses which were strip-grazed every 24-27 days during the rainy season, provided leafy pastures with 12 to 15 per cent crude protein and 60 to 65 per cent digestibility and maintained an average growth rate of 80 kg dry matter/ha/d. The pastures were grazed when they grew to 50-60 cm height and stock were moved on when the pastures were about 15 cm high (Tudsri and Sawasdipanit 1993). In Johore, Malaysia a shorter grazing interval of 17-19 days was recommended (Choo 1993).

What are the modern concepts of nutritive value? These have been related to the energy and protein status of the forage, provided the supply of essential minerals is adequate. A good deal of attention is given to the intake of forage and its digestibility, and management which is directed to increasing the intake of forage (for example, providing leafy forage, supplying legumes which have a fast rate of passage through the rumen), thus benefiting milk production. Recently the actual delivery of nutrients from the rumen and the efficiency of their use has excited more attention (Poppi et al 1997). The balance of nutrients required by the animal is set by its physiological state, which is high for pregnant, lactating animals and lower for dry stock.

The first need is to ensure that the rumen is functioning adequately in terms of the intake of forage being processed and digested. Many tropical grasses are low in protein content, and the intake of these grasses is readily increased by supplying higher protein sources in the diet, for example, legumes, protein supplements such as cottonseed meal, or urea-treated material. In these circumstances the protein production by the microbial population of the rumen is lifted to acceptable levels. Tropical grasses also tend to have low values for non-structural carbohydrates. Therefore, choosing feeds with better characteristics in this respect, such as Pennisetum purpureum and forage Sorghum spp increases not only the level of rumen fermentation but the production of microbial protein. The response by an animal to extra protein is greater when increased intake of metabolisable energy (ME) occurs.

Protein is often used wastefully by ruminants, and perhaps only 11 to 16 per cent of the protein ingested ends up in the final product (Poppi et al 1997). At high levels of protein supply a good deal of ingested protein is lost across the rumen wall as ammonia, and the key ratio for efficient protein use is that forage should not contain more than about 210 g crude protein per kilogram of digestible organic matter. This represents a degradable crude protein (CP) available energy relationship for rumen organisms of 13.3, 11.9 or 9.3 g CP/MJ ME respectively for protein degradability of 1.0, 0.9 and 0.7. Much depends on the degradability of protein which varies greatly among forages. Table 10.1 shows the differing solubility of leaf and stem fractions of a range of plants; legumes like Desmodium intortum with low protein solubility provide more `by-pass' protein to increase milk production directly.

Table 10.1. Protein solubility (%) of leaf and stem of legumes and N-fertilised grasses (Aii and Stobbs 1980).

Plant

Leaf

Stem

Legumes    
Desmodium uncinatum

5.3

36.3

D. intortum

7.6

15.9

Aeschynomene indicata

21.0

48.5

Macroptilium atropurpureum

40.8

52.9

Macrotyloma uniflorum

44.7

54.5

Grasses    
Setaria sphacelata cv Narok

18.6

-

S. sphacelata cv Kuzungula

19.3

44.2

Pennisetum clandestinum

24.0

-

Digitaria decumbens

24.4

37.9

Panicum maximum

25.7

-

Chloris gayana

29.7

53.6

Panicum coloratum

33.4

43.4

Brachiaria mutica

33.5

37.7

Protein protection appears to be related to the content of condensed tannins which form complexes with plant proteins and are then dissociated in the acid conditions of the abomasum. The absence of tannins in the shrub legumes Sesbania spp and Albizzia lebbeck disadvantages them relative to Leucaena leucocephala; on the other hand too high a level of condensed tannins reduces plant intake, decreases rumen ammonia and depresses the post-ruminal absorption of protein.

Further illustrations of the components of nutritive value are given later in the chapter.

Adjusting animal demand and forage supply

At the lower levels of forage supply, milk production responds sharply to an increase in the forage offered. As the supply increases animals eat more selectively, which improves their diet, but a point is reached where further increases in forage supply do not improve milk production and may even reduce it.

This is illustrated for Friesian Holstein cows at Atherton, Queensland in Figure 10.3. These cows were grazing P. maximum var. trichoglume-Neonotonia wightii pastures and received concentrate supplements at zero to six kilograms per cow per day. The pasture on offer was measured as the dry matter of the green fraction on offer. Milk yield of unsupplemented cows increased steeply, up to about 1500 kg green dry matter (GDM) per hectare presented to the animals, and showed a slight further increase to about 2000 kg/ha, and little increase beyond that figure. The relationship between available pasture and milk yield weakened as the level of concentrate feeding increased and less pasture was consumed.

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Figure 10.3. Relationship between milk yield [vertical scale - FCM yield (kg cow-1d-1)] and GDM on offer [horizontal scale- Pasture on offer (kg GDM ha-1x1000)] of Panicum maximum var trichoglume/ Neonotonia wightii for different levels of concentrate feeding (Cowan et al 1975).

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Most smallholder dairy farmers integrate a series of feeds with pastures which are cut or grazed. Where year-round grazing applies, farmers should be aware of how the stocking rate (SR) which is, the number of animals grazed per unit area, influences milk yield. Milk yield per cow decreases as SR increases, although the milk yield per hectare may increase because of the extra number of cows carried. This is illustrated for three experiments in Figure 10.4. In the upper part of the diagram it may be noted that milk yield per cow decreased as SR on P. maximum pastures increased from two cows per hectare to 3.5 cows per hectare. However, milk yield per cow was greater if 400 kg N fertiliser were applied than if pastures received 200 kg N fertiliser per hectare. Milk yield per cow also decreased at the higher SR on the less productive systems of Colman and Holder (1968) and Colman and Kaiser (1974).

It is emphasised again that the response of milk yield to the amount of pasture available or fed is most sensitive when forage is in short supply. In north Queensland (Figure 10.5), the change in milk production per cow as stocking rate increased by one cow per hectare was a reduction (in year two) of 2.4 litres per cow per day in mid-summer December, but the reduction was much greater as the season advanced, and reached 6.1 litres per cow per day, in July.

The dairy farmer needs to adjust the forage allowance according to its nutritive value. Animals should be given an opportunity to reject the lower quality material offered, so that the ratio of utilisation (feed offered/feed consumed) may be quite low if milk production is to be maintained. Forage allowance is further modified by the size of the animal and the notional daily intake as a fraction of body weight. A crude rule of thumb is:

Desirable forage allowance = Intake as a fraction of body weight
   
                                                     Desired ratio of utilisation

Thus for a 300 kg cow eating three per cent of body weight each day and a ratio of utilisation of 0.45, the forage allowance is 20 kg dry matter per day.

Providing continuity of forage supply

Management

Dairy farmers manage the feed supply so as to avoid or to lessen shortages in order to:

1. minimise animal stress, maintain body condition and prevent animal deaths

2. promote successful calving, and

3. sustain milk secretion and the growth of offspring.

Much depends on whether a premium is paid for the year-round supply of fresh milk, which is more costly to the farmer than a system where seasonal supply of milk is the norm.

A good deal of animal stress can be avoided by seasonal calving. Thus, mating female stock at the period of the year which will ensure that the peak demand for forage during late pregnancy and early lactation will coincide with the flush of forage growth. The sale of surplus offspring can be timed to avoid additional animal demand when forage is in short supply.

One approach to reducing the seasonal feed shortage is by changing the environment in which the pasture grows to lengthen favourable conditions for pasture production. The timing of N fertiliser applications can be used to extend the growing season. The growth response per unit of fertiliser applied will be less at the beginning and at the end of the growing season than if applied during the peak of the season, but the additional forage grown is sure to be eaten.

Moisture availability can also be changed by fallowing and storing water for later forage crop planting. The more expensive option is to use irrigation in the dry season; this is feasible when the price of dairy products allows water to be used on pasture rather than on crops. In the subtropics and the high altitude tropics production can be lifted greatly by growing irrigated temperate type pastures, which give much higher quality forage than is possible with tropical type pastures (Chopping et al 1982).

Conservation: Silage

The second major strategy is to conserve surplus forage or crops as hay or silage for use later when feed is in short supply. Hay from tropical grasses is not widely produced, since it is difficult to combine a good yield with satisfactory nutritive value; grasses making vigorous growth rapidly decline in protein content and digestibility decreases as the proportion of stem increases. A prime difficulty is the incidence of rain which interrupts the drying process in the field and causes spoilage of the hay and reduced growth of the pasture due to it being smothered by the cut material. Legume hays are more attractive, but suffer the same risk of spoilage unless grown as special crops on stored soil moisture. In northeast Thailand Crotalaria juncea may be planted on deep soils after the rice harvest and drying the cut forage detoxifies the alkaloid content (Kessler and Shelton 1980). Artificial drying of cut forage is regarded as too energy-intensive and costly for most smallholder dairy farmers.

Silage obviates the need for field curing and fodder crops such as Zea mays and Sorghum spp reliably produce acceptable silage. Silage is the product from a series of processes by which cut forage of high moisture content is fermented to produce a stable feed which resists further breakdown in anaerobic storage. The objective is to retain or augment the nutrients present in the original forage and deliver a silage accepted by livestock; this is usually attained through an anaerobic fermentation dominated by lactic acid bacteria.

Water-soluble carbohydrates are a primary substrate for the multiplication of lactic acid bacteria, which are initially present at low density in the forage, but which multiply rapidly during the initial ensilage process. Organic acids are generated which lower the pH of the material and inhibit the development of undesirable micro-organisms such as clostridia. The fast development of anaerobic conditions is favoured by cutting to short lengths and compressing the material, and a rapid fall in pH constrains the activity of the organisms that lead to spoilage.

Stable acceptable silages usually have a pH of 4.2 or less, lactic acid has 50 per cent or more of the total organic acids, butyric acid not greater than about 0.5 per cent of the dry matter, and NH3N less than 10 per cent of total N.

Quality is first determined by the chemical composition of the forage ensiled. The choice of time of cut is crucial; very young forage will have a high moisture content and low yield; older material will have lower moisture content but may exhibit high fibre and low water soluble carbohydrate content. There are a number of management practices which facilitate the ensiling process.

The first of these is the exclusion of oxygen. The use of plastic wrapping, for example `Silawrap', promotes anaerobic conditions and protects the material in storage. Tjandraatmadja (1989, Figure 10.6) in a series of studies showed the overwhelming significance of anaerobic conditions in making tropical silage production feasible; even lightly permeable polythene bags were inadequate as silage containers. The change in pH of ensiled Sorghum bicolor incubated at different temperatures progressed in a negative direction (Figure 10.6) if ensiled in oxygen impermeable bags, even at 40C. However, silage quality was quite unacceptable, even at 20C, if oxygen could leak into the stack.

As mentioned earlier, many tropical forages are low in water-soluble carbohydrate content. Wilting the forage before ensiling is advocated as a means of increasing these compounds on a fresh-weight basis and of reducing losses from effluent during storage. A further alternative is to add molasses. Legumes, as well as grasses, benefit from this practice, which is facilitated if a sugar mill is operating nearby and selling molasses as a by-product. Table 10.2 shows the effect of adding 2.3 per cent or 4.5 per cent molasses to L. leucocephala. Water soluble carbohydrate was only 6.3 per cent in the fresh material, and incorporating molasses led to a better fermentation, reduced pH, less volatile N and non-protein N, and increased lactic and acetic acids, which was consistent with the reduced population of yeasts and molds found in the silages receiving molasses.

Similarly in Malaysia Mohd Najib et al (1993) found that molasses addition was necessary when ensiling most tropical perennial grasses. Setaria sphacelata and P. purpureum had superior ensiling characteristics (Table 10.3), but satisfactory pH levels in silage from Brachiaria decumbens, B. humidicola, Digitaria setivalva and P. maximum only occurred when molasses was incorporated.

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Figure 10.6. Changes in pH of silages fermented (a) in oxygen impermeable bags (I) and (b) permeable bags (P) at 20, 30 and 40C (Tjandraatmadja 1989).

Table 10.2. Effects of molasses addition on composition of Leucaena leucocephala silage after 28 days (Alli et al 1984).


Indicator

Level of molasses addition
(fresh weight)

 

0%

2.3%

4.5%

pH

4.7

4.3

4.1

Dry matter (%)

38

38

38

Total N (%)

2.8

2.9

2.9

Volatile N (% of total N)

5.6

4.9

4.9

Non-protein (% of total N)

15.5

13.3

11.9

Lactic acid (%)

2.0

4.1

5.0

Acetic acid (%)

0.4

0.6

0.7

Propionic acid (%)

0.2

0.5

0.6

The most reliable silage of good nutritive value comes from Zea mays planted as a forage crop. Sweet corn stover, ensiled after the grain crop has been harvested, also makes acceptable silage. Table 10.4 indicates how the addition of molasses or of urea improves silage quality, but metabolisable energy levels were still low.

Table 10.3. Silage made from grass forages with or without molasses.


Crop species


Nil molasses

4% molasses

 


pH

Lactic acid

Silage quality


pH

Lactic acid

Setaria sphacelata cv Splendida

4.07

2.47

Good

3.64

1.96

Brachiaria decumbens

5.07

1.08

Poor

3.37

1.87

Brachiaria humidicola

5.32

1.26

Poor

3.31

2.03

Digitaria setivalva

4.3

1.46

Poor

3.31

2.83

Pennisetum purpureum

3.96

2.53

Good

2.98

na1

Panicum maximum

4.71

1.84

Moderate

3.27

2.74

Zea mays

3.72

2.72

V. good

na

na

S. vulgare x S. bicolor

3.68

3.75

V. good

na

na

S. almum

4.40

na

Moderate

na

na

1. Not available.

The low protein content of grass silages may be raised by incorporating legumes, but the content of water soluble carbohydrate needs to be carefully monitored. The practice can be recommended with confidence if molasses can be added. Table 10.5 shows the effects of incorporating 33 per cent fresh weight legume in 12-week regrowth of Digitaria decumbens cv Pangola. The forages were all fine-chopped and 4 per cent molasses were applied.

Table 10.4. Chemical composition of sweet corn stover (% dry weight; Yusoff and Teoh 1993).

Parameters

75 days (fresh)

75 days (ensiled, plain)

75 days (ensiled with 1% molasses)

75 days (ensiled with 2% urea)

Dry matter

25.0

23.3 28.1 26.8
Crude protein

9.6

8.2 11.2 12.4
Crude fibre

34.5

33.80 29.7 31.9
Crude fat

1.6

1.6 1.8 1.4
Total ash

8.2

8.2 8.7 8.9
N-free extract

46.1

48.2 48.6 45.4
Phosphorus

0.15

0.22 0.17 0.20
Calcium

0.46

0.46 0.67 0.53
Metabolisable energy (MJ/kg)

7.82

5.86 6.27 6.09

The ensilage produced in airtight drums was of high quality, lactic acid dominated the fermentation, and effluent losses were negligible. Legume addition reduced the production of the unacceptable butyric acid. Cowpea (Vigna unguiculata) material had lower dry matter and N content than the two shrub legumes, and this was reflected in the quality of the silage produced.

Table 10.5. Chemical composition of silages (Tjandraatmadja 1989).

Component (g/kg DM)


Pangola

Pangola + Leucaena

Pangola + Gliricidia

Pangola + cowpea

Dry matter (g/kg)

297

321 319 289
Neutral detergent fibre

624

517 522 583
Acid detergent fibre

388

340 338 377
Hemicellulose

236

177 184 209
Cellulose

342

283 282 330
Lignin

45

56 56 45
Ash

80

74 75 78
Water-soluble carbohydrates

45.7

32.4 44.2 41.2
Total nitrogen (TN)

9.5

17.4 16.1 12.0
NH3-N (g/kg TN)

90

85 78 92
pH

3.99

4.14 4.09 4.04
Lactic acid

41.4

47.6 48.9 51
Acetic acid

9.3

8.5 8.5 12.8
Butyric acid

5.5

3.5 0.3 1.7
Ethanol

13.6

13.7 11.2 19.2

When assessing the value of silage, farmers need to ensure that it is forage surplus to animal requirements during the growing season that is being conserved. This is because any effect of reducing the forage supply on milk production in this period needs to be more than compensated by increased milk production when the silage or hay is fed. It should also be recognised that placing cows on a high plane of nutrition has persistent effects on milk production if the feeding level is subsequently reduced. A study by Davison et al (1982, Table 10.6) showed this effect in cows grazing at Atherton, Queensland which were supplemented with low or high levels of maize silage, with or without meat and bonemeal supplements for an eight week period. Meat and bonemeal had no persistent effect, but the higher level of maize silage feeding increased milk yield by one to two litters per cow per day, and benefited cow liveweight. In the eight week period following the cessation of silage feeding, when the level of pasture on offer decreased due to water stress, cows previously well fed performed better, and their higher liveweight and body reserves helped to maintain milk secretion. Similar effects of high body reserves might be expected to promote conception and reduce abortion. It should be noted that the high level of silage feeding reduced the time cows spent grazing the pasture; supplements are substitutionary as well as additive.

Continuity of feed

Often the most feasible and widely adopted approach to maintaining continuity of forage supply is to use a series of feeds of differing seasonal utility. The growth of the forage plants under differing conditions of temperature and moisture supply, and the rate at which nutritive value deteriorates as the growing season advances, are varied according to plant genetic makeup. The dairy farmer needs plants with a long growing season and superior nutritive value as standing hay.

Table 10.6. Milk yield and composition, milk fatty acids, liveweight change and grazing time of cows during and after a period of supplementary feeding (Davison et al 1982).

 

Low silage1

High silage1

Attribute

U

S

U

S

Total intake of supplement (kg DM/cow/d)


3.0


3.0


7.0


7.9

Milk yield (kg cow/d)
Weeks 1-8
Weeks 9-16


14.3
13.6


15.0
14.0


15.3
15.0


16.6
15.0

Fat (%)

3.66

3.88

3.56

3.23

Solids-not-fat (%)

8.38

8.42

8.54

8.4

Milk fatty acids (molar % C4-C16)
Week 1
Week 2


53.8
54.6


57.3
51.5


57.1
61.5


57.1
56.6

Liveweight change (kg)
Week 1-8


-15.0


-15.4


2.0


11.4

Grazing time (min/d)

497

505

343

293

1. U, nil meat-and-bonemeal; S, meat-and-bonemeal provided in the
ratio 5:1 (silage to meat-and-bonemeal) on a dry-matter basis.

In the previous chapter these attributes were mentioned, especially in relation to shrub legumes, which are well adapted to smallholder situations, especially as a living fence. In Sri Lanka, Chadhokar (1982) observed that Gliricidia sepium planted as a 400 m fence around one hectare of land yielded about 1.1 t/yr. dry weight of green leaf if individual plants were harvested at an interval of three months. Since the material contained about 25 per cent protein, a fence of this size would meet the supplementary protein requirements of at least two milking cows during the dry season. A block planting gave 9.2 t/ha of leaf dry matter.

One of the best examples of a self-sufficient, year-round, feeding system for dairy smallholders in a mixed farming area was devised by Gibson (1987, Table 10.7) and his co-workers in northeast Thailand. Stylosanthes hamata cv Verano and Macroptilium atropurpureum cv Siratro grow well in these soils, and raise soil fertility if fertilised with S and P. Eleven farmers initially undertook to plant 0.64 ha of fertilised legume pasture and acquired two adult milking cows, mostly with a minimum of 50 per cent Friesian heritage.

The composition of the feed supply in the different seasons (Table 10.7) fluctuated in its dependence upon hand feeding. Pastures were heavily used in the main wet season and the early, cool dry season, whilst the rice paddies were mainly grazed in the hot dry season when other grazing was in short supply. Recently harvested sugarcane fields contributed appreciably during the dry season. The volunteer weed component of the cropped areas was a significant feed source.

Table 10.7. Seasonal feeding regimes of crop products and pastures for dairy production in northeast Thailand (Gibson 1987).

 

Season


Feed

Cool dry (Nov-Feb)

Hot dry (Mar-Apr)

Early wet (May-July)

Main wet (Aug-Oct)

Hand feed (kg DM per month per farm)
Rice bran

36

33

45

51

Cassava tubers

64

84

27

61

Cassava tops

3

3

3

24

Sugar-cane tops

58

62

0

7

Crotalaria juncea hay

28

23

7

2

Leucaena leucocephala

24

25

17

3

Rice straw

144

126

0

0

Maize stover

0

0

0

20

Weeds

4

10

22

9

Total

361

366

121

177

Grazing (hours per day)
Legume

6.6

1.2

4.3

7.3

Sugarcane fields

1.2

1.5

0.2

0.1

Rice paddies

1.2

5.4

3.2

1.4

Bush and village

0.2

1.7

1.5

0.4

Total

9.3

9.8

9.2

9.2

The main hand-fed roughage source in the dry season was untreated rice straw and sugarcane tops. Rice bran was fed year-round and was produced on the farm or purchased from local mills. Dried cassava chips were grown and processed on the farm as a high energy source, whose use diminished in the early wet season when other feed sources were available. L. leucocephala was used in the dry season and Crotalaria juncea hay was produced from residual soil moisture in the paddy areas. Minerals were also fed.

In the early phase of this project, milk production (4.4% butter fat) averaged 5.4 l/cow/day with a lactation length of 295 days and calving interval averaged 384 days. Total milk production per farm (two cows) was 3165 l/yr of which 2595 l were sold for US$833 and the balance was mainly fed to calves, who were reared without concentrates.

These practices have been continued successfully, but with some modifications (Udachon and Boonpuckdee 1995). Additions to the list in Table 10.7 may be, corn stover, soybean pod husks, molasses, and Cajanus cajan, whilst Brachiaria ruziziensis- Stylosanthes guianensis cv Graham and P. maximum cv TD58 pastures have been planted. The shrub legume offering has been extended to include Erythrina subumbrans, Desmanthus virgatus and Gliricidia sepium.

A feature of these projects has been the ready adoption by farmers of grazing, rather than of cut-and-carry forage. Where fencing of cropping areas is insecure, tethering gives good results and avoids the immense hand labour involved in cut forage. The return of nutrients to the crop and pasture areas is facilitated by grazing, opportunity for selective grazing to improve diet is maximised, and health problems are lessened. A study at Mueklek, Thailand conducted during the hottest period of the year with 5/8 or 3/4 Holstein Friesian or Red Dane cows showed that day grazing on P. maximum-S. hamata pastures gave the same high milk yields attained if the pastures were cut and fed to the cows in the shed (Hongyantarachai et al 1989). Traditional cut-and-carry practices are being re-examined for their possible replacement by grazing, wherever feasible.

Conclusion

Sustainability of the forage ecosystem is the primary long-term goal. An investment in improving pastures leads to an environment protected from erosion (Humphreys 1994), to the accumulation of organic carbon which militates against global warming, and to the maintenance of crop yields in a mixed farming situation. However these outputs require rational and conservative policies of forage utilisation, which maintain cover on the soil and cycle the nutrients effectively. The deleterious concentration of animal wastes and the transfer of nutrients from adjacent farm lands which are associated with cut-and-carry systems will be mitigated as more smallholders adopt grazing as the norm for dairy animals.

The balance of management objectives is best determined at the individual farm level. The scientist's role is to complement the reservoir of experience and skills developed by smallholders in the husbandry of their animals by providing a hard data base which indicates the probable performance of animals and forages in the many pasture and crop feeding options which are available. Smallholders can then choose from amongst these, the patterns of forage utilisation most suited to their own goals.

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A fodder bank of Leucaena

Field milking the family cow in Ethiopia.

A fodder bank of Leucaena in Cuba.

A Gliricidia fodder bank for milk production in Sri Lanka.

Donkeys carrying teff hay.

Leucaena eaten to browsing height by cattle at Khon Kaen, Thailand.

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