The effects of treatment on forages will depend mainly on the standard of treatment quality achieved which concerns the various parameters described above. They also depend upon the nature of the forage being treated.
This Chapter has the following objectives:
to provide reference standards which indicate good treatment and which allow judgement of treatment efficiency as achieved in the field;
to quantify treatment effects on the nutritive value of treated forages;
to present and discuss field results which have been obtained under various agroclimatic conditions for treating a range of different forages.
It is clear that this last aspect will only have true significance when the results observed on the animals, themselves the best “judges” of treatment efficiency, are those due to the feed having been correctly rationed and fed to them.
This chapter refers to treatments achieved with anhydrous ammonia and that achieved by ammonia generated by urea (called simply, urea treatment even though urea is not the direct treatment agent).
One may judge the degree of treatment success by looking at the physical aspects once the treated forage has been opened up. Physical characteristics indicating good treatment are as follows:
Smell
The criterion of smell can be applied equally well to forage treated by either anhydrous ammonia or urea. A strong pungent smell of ammonia should rise out of the forage mass and remain whilst a handful of forage is pulled out and removed from the enclosure. Lack of smell or only a weak one points to total failure or only low efficiency in the treatment achieved. If one cannot detect a smell of ammonia, it is quite likely that one might notice an unpleasant smell of bad fermentation or of mould.
The smell of ammonia might worry observers with insufficient knowledge who might even ask themselves how their animals will accept this new type of feed. Experience shows that the smell does not upset the animals. Practical indications which should be followed are described below in Appendix 2.
Colour
Forages which have been well treated take on a colour which is dark brown to maroon (Photo 29). This change of colour is particularly marked in straw as initially this is much lighter than for other forages such as, for example, maize stalks. It is easy to judge treatment quality right inside the mass as the colour should be uniform: lighter coloured zones show a weaker reaction of the forage to the ammonia at these points. This is due to a localised under-dosage of ammonia. This observation is often seen after urea treatment and indicates that the urea solution has not been sprayed on uniformly. Alternatively, one might observe darker areas, even blackened ones which show an overdosage. One can overcome these difficulties by mixing up the lighter and darker portions before feeding to the animals.
Texture
A well treated forage becomes softer. This is particularly the case for urea treated forages as water has been added. But even forage treated with anhydrous ammonia becomes softer after treatment.
Where wet forage has been treated and/or the solution has not been applied uniformly, one might notice pockets which are not only brown to black but also deliquescent, imparting a very strong smell of ammonia: these indicate over-treatment due to an overdosage in a very wet zone where the released ammonia has been “trapped” by the excess water: it is better to reject these parts of the forage and not feed them to the animals.
Still considering the case of urea treated forage which used a lot of water, the forage situated at the bottom of the silo or the treatment enclosure might be much damper and darker than the rest through a depth of 10 to 20 cm: it is advisable to mix this with the rest to make it more homogeneous, as long as it is not too deliquescent. Again it should be rejected if it is too wet and black.
Absence of mould
Well treated forage has no mould as its development is suppressed by the ammonia atmosphere within the forage mass. Furthermore, one can take advantage of this property to conserve forages which are too wet to make into silage (for example, the authors have done this on a large scale in a temperate zone with spaths and maize stalks).
Absence of mould is a good indication of good hermetic sealing of the treatment enclosure. One might notice in the case of forages which have been apparently well treated in bulk with urea, that one finds white mould developing on the surface because these parts are no longer being protected by the ammonia atmosphere. These cases which are not serious, are more frequent with urea treatment where the forage has been dampened, rather than the drier treatment achieved with anhydrous ammonia. These fringe moulds can, paradoxically, appear on forage treated by urea at either high or low moisture contents. They are however, much more common when the forage is wet. No mould will appear if the forage mass, even if wet, is hermetically sealed.
In certain rare cases in temperate regions and when treatment and conserving damp forages (DM less than 40 %) such as maize stalks made into round bales before being properly dried, the authors have sometimes noticed development of green mould following well defined veins within the bales. Although rare, this case is dangerous as this mould is toxic. Feeding this forage should be avoided as it can rapidly cause serious poisoning.
As a general rule, one should avoid feeding the animals with either straw or forage which in any way is contaminated by mould: one should take samples and decide if mould only exists on the outer edges where the forage has been in contact with the air. If contamination is too serious, one must reject the totality of the feed.
Classical chemical analyses (proximate analysis) do not allow correct evaluation of the nutritional value of low quality and highly lignified forages, particularly straw. The same is the case for treated forages (CHENOST and REINIGER, 1989).
This consists of a very general and heterogenous criterion from the bio-chemical point of view, and one which is not sufficiently precise to yield information concerning the content of parietal constituents in either natural or treated straw. Crude fibre content determination does not allow distinction between treated or non treated straw. Furthermore the analysis is expensive and therefore it is not worth undertaking.
This series of treatments allows a better determination of:
the overall content of the parietal elements (Neutral Detergent Fibre or NDF),
the composition of this parietal fraction:
ADF (Acid Detergent Fibre), representing the ensemble of lignin plus cellulose;
NDF - ADF, roughly representing the hemicelluloses;
the lignin ADF, representing the lignin;
ADF - lignin ADF, roughly representing the true cellulose.
Even here though, these different criteria do not yield sufficient information regarding the actual nature of the parietal fraction of low quality forages: their structure and above all, the distribution of the lignin in these cells which will determine in fact their degradability and their digestibility. They do not illuminate the nature of the biochemical modifications caused by the treatment. And so it is, as shown in Table 6, that despite the improved digestibility achieved by treatment, the NDF levels of these forages remain unchanged. As was already described in Chapter 1, treatment basically consists of breaking the lignin/hemicellulose bonds to the cellulose (Figure 10) which will not alter their overall concentrations. Determination of these fractional values therefore, is of little practical interest.
| Straw | Dry Matter | Mineral content | Crude Protein | Neutral Detergent Fiber (N D F) | Acid Detergent Fiber (A D F) | Acid Detergent Lignin (A D L) | Digestibility (%) |
|---|---|---|---|---|---|---|---|
| Non treated | 90 | 9 | 3 | 76 | 47 | 4 | 46 |
| Treated | 64 | 7 | 14 | 75 | 49 | 5 | 59 |
Figure 13: Schematic representation of the respective proportions of the treating nitrogen (%) which are lost or fixed and usable by the rumen microorganisms.
The additional nitrogen which is contributed by treatment with either anhydrous ammonia or urea, is partially retained by the straw. The nitrogen fixation ratio determines the proportion of nitrogen retained as compared to that injected or applied during the treatment (Figure 13). The average ratio is about 30 %, a figure based on a series of trials in temperate regions undertaken on straw of diverse botanical origin, in summer, both on Station and on farms and with ammonia application rates of between 3.5 and 5.0 kg per 100 kg of forage matter (DEMARQUILLY et al., 1989).
The nitrogen content of treated forage depends on the fixation ratio. This latter is thus a good indicator of treatment efficiency.
The portion which is fixed is itself made up of two fractions (see Figure 11)
one fraction (a little less than half) which is “fixed” by adsorption of the ammonia on the vegetal matter. This fraction is however unstable and will gradually be lost once the treated straw is opened up and if it is then left too long in the open air. This fraction, which is soluble in water, is used by the rumen microbes;
another fraction (a little more than half) which is no longer ammonia; it is chemically fixed to the cells of the straw and is insoluble in water. One portion (25 to 30 % of the total fixed nitrogen) is soluble in neutral detergents and is also used by the rumen microbes. The other portion (30 to 35 % of the fixed nitrogen) is solidly bonded to the indigestible cells, is insoluble in neutral detergents and remains unused by the rumen microbes.
The bibliographic review by DEMARQUILLY et al. (1989) shows an increase in crude protein of:
58 g +/- 20 g per kg of straw DM
This increase is very variable and seems to be related to the initial nitrogen content of the straw. It depends very little on the ammonia dosage when this lies in the range of 3.5 to 5.0 % (the fixation ratio reduces for higher values); in contrast, the increase is more marked at higher levels of moisture content and when the straw remains longer in the ammonium atmosphere, particularly when outside temperatures are low. It increases with treatment duration.
One may conclude that the increase in crude protein content is a good indicator of treatment efficiency.
The special case of urea treatment:
The crude protein level of forage after treatment can form a topic for discussion and some misinterpretation, depending upon whether the ureolysis has been complete or only partial. It is well understood that during urea treatment, one aims to achieve complete ureolysis so as to obtain maximum effect from the ammonia (see above discussion of the factors affecting successful urea treatment).
It is however possible that, for various reasons (§ 42), ureolysis might not have been complete and that some urea will remain within the forage. In this case, the nitrogen content of the forage will be high, despite the fact that the “alkaline” treatment has been only partial due to the amount of ammonia released being not as high as expected. So the high nitrogen content is no longer a good indicator of treatment efficiency as it includes some nitrogen from the residual urea itself.
Should one try to determine the amount of residual urea? Such a determination is delicate and expensive and presupposes availability of well equipped laboratories. One could not consider it under normal practical circumstances. There is however a way to overcome this difficulty, based only on the total dosage of nitrogen. This may be illustrated by the following example:
Let us take the example of straw with an initial crude protein content of 4 % which is treated with 6 kg of urea per 100 kg of straw DM:
First hypothesis - there is no ureolysis:: the added nitrogen will remain only in the urea, which is:
6 x 46/100(1) x 6.25 = 17.25 points of Crude Protein
the straw, after treatment, will therefore have a total amount of crude protein equal to:4+17.25 = 21.25%
Second hypothesis - ureolysis is complete: the added nitrogen is all transformed into ammonia, which is:
6 x 57/100(2) x 82/100(3)×6.25 = 17.5 points of crude protein (ammonia) of which about 1/34 is fixed by the straw, which is:
17.5 x 1/3 = 5.8 points of Crude Protein
the Crude Protein content of the straw after treatment will thus be: 4+5.8 = 9.8%
(1) 46 g of N per 100 g of urea
(2) 57 g of NH3are generated per 100 g of urea (§41)
(3) 82 g of N per 100 g of NH3
(4) this fixation ratio is certainly a little underestimated because during urea treatment, one adds water which favours fixing the nitrogen
It is thus seen that in the case of urea treatment when one is unsure of the success of ureolysis, a first order estimation may be made by first estimating the amount of nitrogen which should be present if ureolysis is complete, based upon N × 6.25 (Kjeldahl):
ureolysis will be correspondingly less complete as the measured crude protein content rises above this estimated value; ureolysis is probably still complete when the crude protein content is between 9 and 12 %; it is likely to have been a total failure if it rises above 20 %, at least for the case of straw with an initial protein content of 4 % and with a urea dosage of 6 kg per 100 of straw.
Incomplete ureolysis will not necessarily mean that the straw cannot be used but one must make sure that ingestion is regular and be vigilant concerning the addition of fermentable energy supplements (adding PDIE) as with the straw being rich in urea and hence non protein nitrogen (NPN), it will contribute more PDIN than foreseen (hence the optimum equality PDIN = PDIE will not be achieved).
However in tropical countries, ambient temperature favours ureolysis which is almost total and the increases in crude protein content (N × 6.25) shown in Table 7 (66 g +/- 30 g per kg DM) constitute a good indication of successful treatment.
| Straw | Urea (%) | N × 6.25 | References | ||
|---|---|---|---|---|---|
| NT | T | Increase T - NT | |||
| RICE | 5 | 3.1 | 6.7 | 3.6 | DOLBERG et al. (1981a) |
| BARLEY | 4 | 4 | 14 | 10 | ABDOULI et al. (1988) |
| WHEAT | 4 | 4 | 14 | 10 | GUPTA et al. (1986) |
| WHEAT | 5 | 5 | 11 | 6 | NYARKO et al. (1993) |
| WHEAT | 5 | 5.5 | 12 | 6.5 | RAMANA et al. (1989) |
| RICE | 5 | 4.8 | 9.2 | 4.4 | GIHAD et al. (1989) |
| RICE | 5 | 4 | 8 | 4 | WANAPAT et al. (1985) |
| RICE | 5 | 4 | 16 | 12 | GUPTA et al. (1986) |
| WHEAT | 4 | 2.4 | 9.5 | 7.1 | RAHMAN et al. (1987) |
| RICE | 4 | 5.9 | 8.5 | 2.6 | TRUNG et al. (1988) |
| BARLEY | 5 | 3 | 8 | 5 | KADZERE and MEULEN (1986) |
| RICE | 5 | 2.9 | 6.7 | 3.8 | SAADULLAH et al. (1981 a) |
| RICE | 6 | 4.1 | 8.2 | 4.1 | DJAJANEGARA et DOYLE (1989) |
| RICE | 6 | 4.5 | 14 | 9.5 | KAYOULI (1988) |
| WHEAT | 5 | 3 | 14 | 11 | BA (1993) |
| AVERAGE | 4.0 | 10.6 | 6.6 | ||
| Standard deviation | 1.0 | 3.0 | 3.0 | ||
NT Non treated straw
T Treated straw
Ash content is an interesting measure which can reveal the importance of any forage contamination which might have occurred initially due to soil or sand and the importance of the mineral fraction of rice straw which is very rich in minerals (due to the silica). Ash content cannot serve as an indicator of treatment effects as it is not present in either the ammonia or urea, the treatment agents. In the limit, it may be used as an indicator of losses of soluble elements during treatment if the forage is then observed to have an ash content significantly lower than the untreated forage.
Ammonia treatment improves the digestibility of straw and low quality forages. A bibliographic study has already been cited which describes the increase in nitrogen content due to various treatment methods with anhydrous ammonia and urea. The same study shows that increases in OMD are very variable and reflect differences in treatment techniques, the amount of ammonia incorporated, the ambient temperature, the treatment time and the type of forage treated; they also depend upon the method by which digestibility is measured (the quantity and nature of the supplements added which gives an expression for the potential digestibility, taking into account the phenomenon of associative digestibility, hence calculating the actual digestibility of the straw in the ration).
The incremental increase in digestibility, Δ OMD, is on average, more significant for forage with a lower initial digestibility prior to treatment, OMD.i, (initial organic matter digestibility); to a lesser extent Δ OMD rises as the incremental increase in crude protein content, Δ CP, becomes more important:
Δ OMD = 20.32 - 0.247 OMD.i + 0.032 Δ CP (%DM) + 3.14 R = 0.591 n = 56
This increase is respectively, 14.2, 11.9 and 9.8 points for an initial digestibility of 30, 40 and 50 %.
How can this increase be predicted in the field without performing measurements on the animals?
One should recall, just as for non-treated straw, classical chemical analyses do not allow prediction of the digestibility of properly treated straw. One must therefore revert whenever possible, to biological tests in the laboratory (CHENOST and REINIGER; 1989).
Without entering into further details at this juncture, one may summarize by saying that the only relatively simple tests are as follows:
determination of the in vitro digestibility (IVD),
determination of in sacco digestibility (nylon bags).
These two groups of measurements require using animals carrying a rumen fistula (donor animals) which consume a “cellulolytic” ration (whereby the rumen microbes are able to normally degrade the cell walls of the forage under test);
determination of the cellulase digestibilities which calls upon the cellulolytic enzymes (the cellulases) whose activity must be perfectly standardised.
These measurements only show relative variations in digestibility (the increase in digestibility as compared to that of the untreated forage). The values cannot therefore be considered as true values of OMD if one has not previously determined, for the known digestibility in vivo of the forages (measured on the animals), the equations which allow “transfer” of the in vitro values to the corresponding in vivo values. These measurements imply two analyses, one before and one after treatment.
Table 4 gives the values of N × 6.25 and of the estimated digestibility as determined by these methods for a range of forages and straw which were treated with urea under different climatic conditions and on true large scale on farms. The average rise in digestibility is 10 points, a value which compares well with the generally agreed standards described above.
Treatment increases the crude protein content and also the apparent digestibility. The result is an increase to the Digestible Crude Protein (DCP) which on average will rise from 0 before treatment to values reaching 30 to 40 g/kg DM afterwards (see Table 8).
How is the DCP used by the animal?
Without entering into too much detail, one may summarize by saying that the utilization of nitrogen by the animal is less than what one would normally expect due to the increase in the level of crude protein. In practice, treatment involves an increased loss of nitrogen through faecal excrement (BORHAMI et al., 1981; WINTHER et al., 1983; CHENOST et al., 1987; RAMIHONE, 1987; DEMARQUILLY et al., 1989; MASON et al., 1989, amongst others). This increased faecal loss is due to:
| Parameters | Non treated | Treated |
|---|---|---|
| Crude Protein(% DM) | 3 – 5 | 9 – 10 |
| DCP(g/kg DM) | 0 | 30 – 40 |
| OMD(%) | 35 – 45 | 50 – 60 |
| UFL(per kg DM) | 0.40 – 0.45 | 0.55 – 0.65 |
| PDIN(g / kg DM) | 22 | 44 |
| PDIE(g /kg DM) | 44 | 55 |
| Indigestible Crued Protein(g /kg DM) | 40 | 60 |
the nitrogen fixed to the indigestible cell walls,
the microbial nitrogen arising from further microbial fermentation in the large intestine and which has not been able to be digested (HASSEN et al., 1992).
and finally, poor utilisation by the rumen microorganisms of the nitrogen added through the treatment action, although degradation might reach a level of 90 % (MICHALET-DOREAU et al., 1989); this poor utilisation is indicated by the presence of nitrogen in soluble form, in the faeces of treated forages (HASSEN et al., 1992).
In more practical terms, this latter point implies:
over-estimation of the nitrogen value of treated forages will occur if one uses classic calculation methods which do not take this phenomenum into account. One should also take account, as will be shown in Chapter 6, the amount and quality of the nitrogen supplements which have been added to the treated forages so as to fully exploit their potential, particularly when high performance rates are expected from the animals being fed.
the faeces of the animals consuming these treated forages are richer in nitrogen (see Tables 9 and 10).
| Forages (straw, stalks) | Crude Protein content % DM of the corresponding faeces | ||
|---|---|---|---|
| INRA, 1988 | |||
| Non treated | 9.5 | ±0.6 | n = 7 |
| Treated with ammonia | 15.6 | ±2.6 | n = 7 |
| Treated with urea | 13.8 | ±1.3 | n = 4 |
| Treated with caustic soda | 10.8 | ±0.9 | n = 4 |
| Demarquilly et al., 1989 | |||
| Non treated | 6.3 | nd | n = 18 |
| treated with ammonia | 11.4 | nd | n = 18 |
| Kayouli, 1994 b | |||
| Non treated | 6.4 | 1.8 | n = 5 |
| Treated with ammonia | 11.4 | 2.6 | n = 5 |
| Nature of the treatment | g Crude Protein/kg DM | g MAND / kg DM | MAND due to treatment as % of crude protein supplied through treatment (*) | ||
|---|---|---|---|---|---|
| straw | straw intake | ||||
| Value | Increases | Value | Increase | ||
| Non treated (NT), n = 18 | 33.5 | 38.0 | |||
| Treated with ammonia | 97.5 | 64.0 | 56.5 | (TNH3 - NT) = 18.5 | 29 (1) |
| (TNH3), n = 18 | (TNH3 - TNaOH) = 12.1 | 19 (3) | |||
| Treated with caustic soda (TNaOH), n = 18 | 33.5 | 0.0 | 44.4 | (TNaOH - NT) = 6.4 | 10 (2) |
(*): the fraction of the crude protein supplied by the ammonia treatment which apparently remainsunused (1), due to the alkaline effect (2) and the fraction of the ammonia which is truly indigestible (3)
Furthermore and in conclusion, Table 8 shows that both straw and all other low quality forages which are treated with ammonia or urea, have nitrogen values which are not only higher but which are also almost balanced in contrast to untreated forages, to which one would need to add nitrogen so as to enhance the PDIE value (otherwise this would remain only “potential”)
Ingestibility is an individual characteristic of forage which describes its aptitude to be voluntarily ingested in either larger or smaller quantities. The Fill Value of Forage (FVF, which is the French VEF) is expressed in Fill Units (FU, UE in French), (INRA, 1988). Higher values indicate forage with lower rates of ingestibility. For a given species, it is independent of the animal's appetite, this being expressed in terms of its Capacity of Intake (CI), (INRA, 1988).
Capacity of Intake varies according to the race, sex, physiological condition (gestation, lactation, fattening, etc.…) and the local environmental conditions where the animal is kept.
And so, the amount of feed given the animal which it can ingest is the quotient:
Capacity of Intake CI (kg DM) / Fill Value (FU)
| of the animal | of the forage which it takes voluntarily |
Measurement of ingestibility and Capacity of Intake is delicate and is carried out in-station under well standardised conditions on a large number of animals and with various repetitions over a period of time.
There is very little data available comparing the ingestibility of untreated and treated forages. Treating straw increases its ingestibility (reducing its FVF) but in a proportion which varies considerably according to treatment quality and the nature of the straw. Ammonia treatment of straw causes a partial reduction in the Fill Value of Forage (FVF) of between 1.80 and 1.30 (INRA, 1988). Ingestibility therefore rises by about 40 %.
In practice however, one cannot really talk in terms other than increase of intake, with all the sources of variability which this implies (types of animal, feeding conditions: the portion of supplement in the ration, local environmental conditions, success of the treatment,…).
Table 11 presents the results from 17 feeding trials, showing the amounts of DM intake for cattle and buffalo consuming either treated or untreated rice straw. The average increase of DM intake per day and per animal of treated straw was about 30 % when compared with untreated straw (with extreme values ranging from 15 to 50 %). These increases are of the same order of magnitude as observed in various cattle trials in a temperate region (Demarquilly et al., 1989).
These figures are only indicative. In fact the increase of the intake is extremely variable and depends on:
the treatment quality
the proportion of straw in the overall feed ration: response will be more marked for higher proportions of straw (Chap.6)
the nutritional condition of the animal: response will be greater for animals with an initially poor nutritional condition.
An important point to note is that, in addition to the changes in physical aspect described above, certainly the best criterion for judging treatment success is by looking for increases in the intake.
Table 8 summarises average rises in the feeding value of straw which successful ammonia treatment can provoke.
| Animals | Urea | DM straw intake (kg / day) | Weight gain (g / day) | References | ||||
|---|---|---|---|---|---|---|---|---|
| Liveweight (kg) | (kg/100 kg of straw) | Non treated | Treated | Increase | Non treated | Treated | Increase | |
| Buffalo(200) | 5 | 4.21 | 4.75 | 0.54 | -182 | 79 | 261 | Wanapat et al., 1984 |
| Buffalo(290) | 3 | 5.87 | 6.42 | 0.55 | -130 | -50 | 180 | Wongsrikeao &Wanapat, 1985 |
| 6 | 5.87 | 7.32 | 1.45 | -130 | 210 | 340 | ||
| Cattle(60) | 5 | 1.70 | 1.90 | 0.20 | 35 | 110 | 75 | Saadullah et al., 1982 |
| Cattle(130) | 5 | 2.93 | 3.68 | 0.75 | 125 | 310 | 185 | Khan et al., 1982 |
| Cattle(170) | 4 | 2.09 | 2.84 | 0.75 | 73 | 346 | 273 | Perdok et al., 1982 |
| Cattle(120) | 3.40 | 3.30 | -0.10 | 224 | 306 | 82 | Saadullah et al., 1982 | |
| 3.30 | 3.40 | 0.10 | 193 | 295 | 102 | |||
| Cattle(285) | 5 | 4.97 | 6.82 | 1.85 | -134 | 430 | 564 | Wanapat et al., 1982 |
| 5 | 2.69 | 4.82 | 2.13 | -312 | 75 | 387 | ||
| Cattle(65) | 5 | 2.00 | 2.20 | 0.20 | 107 | 295 | 188 | Hamid et al., 1983 |
| Cattle(125) | 5 | 2.40 | 4.80 | 2.40 | 114 | 227 | 113 | Haque and Saadullah, 1983 |
| 5 | 2.40 | 4.60 | 2.20 | 132 | 227 | 95 | ||
| Cattle(165) | 4 | 3.39 | 4.19 | 0.80 | 141 | 308 | 167 | Kumarasuntharam et al., 1984 |
| 4 | 3.39 | 4.75 | 1.36 | 141 | 207 | 66 | ||
| 4 | 3.39 | 3.94 | 0.55 | 141 | 336 | 195 | ||
| Cattle (-) | 4 | 2.00 | 3.00 | 0.90 | 103 | 282 | 179 | Perdok et al., 1984 |
| Average | 3.29 | 4.28 | 0.98 | 38 | 235 | 203 | 11 references, 17 trials | |
| std. dev. | 0.76 | 127 | ||||||
In conclusion, the increase of the intake will constitute, along with the changes in physical aspect (colour, smell, texture), the best criteria for judging success of the treatment as these are the direct consequences of the increase in feeding value. This would be an excellent starting point for the field extension agent.
Ammonia treatment, which may be undertaken either directly with anhydrous (or aqueous) ammonia or indirectly with urea, allows improvement to the digestibility and the intake of low quality forages. It also allows improvement to the nitrogen value which represents an additional advantage when compared to treating with caustic soda or other alkaline reactive agents. There are no major differences between urea treatment and ammonia treatment as regards their effect on the forages and less so when equal quantities of ammonia are ensured (that is to say, in the case of urea treatment, when there is a total hydrolysis of the urea). The advantage of urea over ammonia seems to be the possibility of reducing the amount of urea below the theoretically required quantity without reducing its beneficial effect; this is certainly due to the fact that the action of generating ammonia is improved by the higher moisture content involved with urea treatment. In contrast it seems that response to increasing amounts of urea is less marked than that of increasing quantities of anhydrous ammonia.
Anhydrous ammonia treatment presupposes availability of ammonia in the country together with a distribution network, appropriate equipment (storage tanks, trucks, …) and of trained personnel for its handling. This technique is thus only appropriate in those countries and for those farms which are well organised and equipped. Tunisia and Egypt are two good examples where this technique has been put into practice.
Where there is lack of ammonia or where organisation for its distribution and handling would be too difficult or onerous, urea treatment constitutes a perfectly valid alternative. Results of analyses and field observations are in agreement with classical results. Moreover, they show that urea treatment is efficient even when locally available materials are used. Equally, they show that the treatment conditions and parameters which have been adopted were correct.
This technique has been introduced to numerous countries of which the majority now use it currently. It is particularly well adapted for small isolated farms. It can also be established on large or cooperative farms. In this last instance, it is even feasible to mechanise the treatment.
Treatment of low quality forages is not the only means to improve their utilisation by the animal. Nutritive elements lacking in the forage can be added through other food crops as a supplement to the low quality forage.
These additional possibilities through the use of supplements will now be described, serving for optimising the utilisation of non treated forages or for optimising the utilisation of treated forages.
Photo 1: Harvesting bush straw (Cenchrus biflorus (cram-cram) and Schoenefeldia gracilis towards the end of the dry season in Mauritania. Photo. Chenost.
Photo 2: Treating straw in a stack with anhydrous ammonia, using a mobile tank of 500 kg capacity (Tunisia). Photo. Chenost.
Photo 3: Treating a stack of straw with anhydrous ammonia supplied from a 30 kg bottle (Tunisia). Photo. Chenost.
Photo 4: Filling a mobile tank of 500 kg capacity with anhydrous ammonia from a “mother” tank of 2,000 kg capacity (Tunisia). Photo. Chenost.
Photo 5: A batch of rice straw in the Egyptian delta region, ready to be injected with anhydrous ammonia from a truck tanker belonging to the cooperative. Photo. Chenost.
Photo 6: Treating round bales of maize by the “Armako” technique showing mechanised wrapping in plastic sheeting, followed immediately by injection with ammonia (France). Photo. Chenost.
Photo 7: Urea treatment in a pit (in Tanzania): the airtight seal has been achievea here with banana leaves (one may also use the stalks). Photo. Chenost.
Photo 8: Urea treatment in a pit (Madagascar): the airtight cover has been achieved here by using strips of plastic from bags which have been stitched together. Photo. Chenost.
Photo 9: Urea treatment in a battery of two silos made from banco (Mauritania). Photo. Chenost.
Photo 10: Urea treatment in a battery of two silos made from banco (Mauritania). Photo. Chenost.
Photo 11: Making an enclosure for urea treatment using séko (Niger). Photo. Kayouli.
Photo 12: Panniers and shelters which may serve for urea treatment of straw (Cambodia). Photo. Kayouli.
Photo 12': Panniers and shelters which may serve for urea treatment of straw (Cambodia). Photo. Kayouli.
Photo 13: A traditional grain store on stilts which has been adapted for urea treatment by using plastic strips and plaited mats (Cambodia). Photo. Kayouli.
Photo 14: A local silo for urea treatment constructed with a wooden framework and with walls made from plaited mats (Cambodia). Photo. Kayouli.
Photo 15: A local shelter arranged for urea treatment by making walls from sheaves of straw (Cambodia). Photo. Kayouli.
Photos 16 &16': Adaptation of a traditional grain store on stilts for urea treatment of straw (Cambodia). Photos. Kayouli.
Photo 17: Demonstration of urea treatment within a butyl sack (Jordan). Photo Chenost.
Photo 18: Traditional stocks of straw bunches with inclined roofing constructed from the same type of straw bunches (Cambodia). Photo. Kayouli.
Photo 19: Traditional stacks of straw bunches with inclined roofing constructed from the same type of straw bunches (Cambodia). Photo. Kayouli.
Photo 19': A traditional stack in Madagascar. Photo. Chenost.
Photo 20: Hand sprinkling the solution of urea for treating a heap (Tunisia). Photo. Chenost.
Photo 21: Batch treatment of compressed maize stalks using a mechanised system, layer by layer, on a cooperative farm (Tanzania). Photo. Chenost.
Photo 22: Mechanised treatment of wheat straw in the field (France): the water and the urea are applied separately as the straw mounts the pick-up mechanism before the round bale is formed. Photo. Chenost.
Photo 23: Calibrating a simple weighing system for a bunch (sheaf) of straw of a given circumference by measurement with a length of cord (Madagascar). Photo. Chenost.
Photo 24: Preparing bunches of rice straw using the knotted cord and as calibrated beforehand (Madagascar). Photo. Chenost.
Photo 25: Urea treatment of straw in a silo made from séko grass (Niger). Photo. Kayouli.
Photo 26: Sewing together recycled plastic bags to make strips of plastic sheeting (Mauritania). Photo Chenost.
Photo 27: Urea treatment of straw in a silo made from séko grass (Niger). Photo Kayouli.
Photo 28: Urea treatment of straw in traditionally made stacks (Cambodia). Photo. Kayouli.
Photo 28': Urea treatment of straw in traditionally made stacks (Cambodia). Photo. Kayouli.
Photo 29: Colour of rice straw after good treatment. Photo Kayouli.
Photo 29': Colour of rice straw after good treatment (Cambodia (a) and Madagascar (b)). Photo. Kayouli.
Photo 30: Preparing the fabrication of multinutrient blocks based on rice bran and molasses (Cambodia). Photo. Kayouli.
Photo 32: Making a small number of multinutrient blocks (Cambodia). Photo. Kayouli.
Photo 33: Making a small number of multinutrient blocks (Cambodia). Photo. Kayouli.
Photo 34: Making a small number of multinutrient blocks (Cambodia). Photo. Kayouli.
Photo 35: Drying multinutrient blocks in the shade after removal from the moulds (Cambodia). Photo. Kayouli.
Photo 36: Making multinutrient blocks at artisanal level (Niger). Photo. Kayouli.
Photo 37: Making multinutrient blocks at artisanal level (Niger). Photo. Kayouli.
Photo 38: Making multinutrient blocks at artisanal level (Niger). Photo. Kayouli.
Photo 39: Draft oxen working in rice fields (Madagascar). Photo. Chenost.
