The objectives and production methods in the majority of developing countries in the tropics are quite different to those in temperate countries with developed economies. In addition, feed for ruminants in these countries generally relies upon low quality forages with the further constraint that these are normally only available during certain seasons. Resulting rates of animal production are thus weak or only moderate. To envisage high production levels implies recourse to important amounts of feed concentrates which are often imported and expensive. Such production systems are not realistic. The basic objectives of these countries are likely to be better expressed as follows:
to maintain the weight, or even the very survival of the animals through the dry season,
to ensure the draft animals are in a condition to be able to undertake work at the start of the cropping season,
to reach modest but realistic milk production figures for each cow (increase of one to two litres per day),
to obtain beef cattle showing a weight gain of the order of 300 to 600 g/day.
The objective of this Chapter is to demonstrate how, through the use of techniques to increase the feed value of low quality forages, one may contribute towards achieving these objectives.
A number of case studies concerning more intensive animal production systems will be presented (from North Africa, the Near East, China, … where livestock and cereal production are well integrated) where these techniques can be of interest for certain categories of animal.
The improvements allowed through use of these techniques must always be well reasoned so as to remain both realistic and economic from a nutritional point of view.
Farmers are generally unanimous in remarking upon the positive effect on their animals when these regularly receive multinutrient blocks over a period of sufficient length (several weeks). A summary is presented below concerning the observations remarked on by farmers practising both crop and livestock production in Tunisia, Niger, Cambodia and Laos:
An increase in appetite of the animal, which translates into improved intake of low quality forages and/or the length of time spent pasturing. Women from Niger (Dosso Department, Tibiri Sector) report that their sheep even eat groundnut husk which was normally refused previously. Women from Cambodia (Kandal Province) observe that their cows are less selective when pasturing. A similar situation exists in Northern Tunisia (the zone of Aïn Draham) in the forest shrub which is much better exploited by goats who “fall upon” the multinutrient blocks after their return from pasturing.
An increase in the amount of water consumed, probably due to the increased ingestion of minerals but also to the total amount of dry matter ingested.
A good maintenance of liveweight throughout the dry season and improvement to the general condition of weaker, thinner animals.
Improvement to the animal's fleece or hide, which becomes more brilliant.
Improvement to the work capacity of the draft animals.
The animals stop licking each other and licking stones, the soil, walls and stop searching to eat plastic, rags and bones. This licking habit is often due to mineral shortages, mainly salt and macro-elements which are supplied in the multinutrient blocks.
The main effect of feeding multinutrient blocks is to increase the intake of low quality forage. This is highly significant. If one examines the combined results presented in Table 21, one notices that the average increase in intake for cereal straw (rice or wheat) is some 28 %. This increased intake, as mentioned previously, is due to the resulting intense microbial activity. An increase in nitrogen supply has also been reported (TIWARI et al., 1990) which passed from 31 g to 67.5 g/day for young buffalo feeding from straw supplemented with either 1 kg of concentrates or with 750 g of multinutrient blocks. This increased supply is also accompanied by better efficiency in using the nitrogen from the blocks.
|(kg DM/day)||ADG (g/day)|
|Sudana et Leng (1986)|
|Tiwari et al. (1990)|
|Station de Niono, Mali (1993)|
|Hadjipanayiotou et al. (1993)|
|Lambs (n=35) wheat straw||ND||ND||-88||-58|
|Ewes (n=16) wheat straw||ND||ND||41||67|
|Ewes (n=83) stubble||ND||ND||-56||-6|
|Nyarko et al. (1993)|
|Ewes (n=30) wheat straw||43 (1)||60 (1)||-2.8||6.4|
(1) in g/kg W 0.75 where W is Liveweight
O = without blocks
B = without blocks
ND = not determined
The increased intake is often accompanied by greater consumption of water. In a trial conducted in Pakistan, three groups of young buffalo were fed a ration based on wheat straw, green forage and silage made from oats; this was either fed alone or with multinutrient blocks; those groups which were also supplied with the blocks consumed 25 % more water (ALI et al., 1986).
The results presented in Table 21 show that consumption of the blocks (from 100 to 250 g for small ruminants and 400 to 800 g for cattle and buffalo) significantly improved the performance of the animals. With these rations which only consisted of straw, use of the blocks significantly limited weight loss and allowed the animals to be maintained throughout the dry season. When comparing alternatives for feed supplements, rations based on low quality forages are generally better exploited by supplementing them with blocks made from molasses and urea than by adding concentrates (NYARKO, 1993). Another trial was undertaken by a research team from the Sahel Animal Production Research Station at Niono, Mali (1990) where the following three types of supplement were investigated: salt, multinutrient blocks and a commercial feed concentrate (1 kg) with three groups of Zebu cattle which were maintained by pasturing for five months (March to July). Weight gains observed were + 192 g/day for the “block” treatment as compared with -410 g/day and -99 g/day for the “salt” and “concentrate” treatments respectively.
One of the most remarkable aspects concerning this subject is that, whatever the agro-ecological situation of the livestock farmer, opinions converge in each case (in Togo, Niger, Tanzania, Madagascar, Morocco, Mauritania, Tunisia, Egypt, Cambodia and Laos). Opinions are as follows:
a/ An increase in the consumption of feed (often noticed as a “passion” for the treated forage). However, and accounts are systematic in their observations, such passion only is achieved after several days or even a week from when this type of feed has been introduced to the animals. At the same time, farmers notice that their animals eat the treated forage “more quickly”. When this is given ad libitum, refusal is less common than with the previous non treated roughage, particularly as regards stalks of millet, sorghum or maize. Whilst the animals used to only eat the leaves and the ends of the stalks, leaving the main portion, they eat practically the entire ration when it has been treated. This remark is further emphasised by the observation that the stalks easily break into small pieces following the trampling and compression received during treatment in the silo. In a single word, the feed is more “appetizing” than before. Once stocks of treated feed have been exhausted, farmers notice a sense of dissatisfaction by the animals for the non treated roughage when there are problems to renew supplies.
b/ An increase in the amount of water consumed by the animal, particularly noticed when drinking water is physically supplied to the animal (when it is tethered or in a stable). The number of drinking sessions tends to rise from one or two per day, up to three or four.
c/ A general improvement to body condition (the best level of “stoutness” often becomes apparent). Those animals receiving the treated forage (either as a basic ration or as a supplement) tend to maintain their liveweight throughout the dry season, have less parasites and are more resistant to disease. Their pelt is more brilliant. Weak or thin animals which are put on a diet including treated forage, recover quickly and their general condition improves over the course of the first few weeks (about three weeks on average), depending upon the amounts given. Several farmers in Niger have saved cachectic animals towards the end of the dry season, thanks to feeding them treated straw.
d/ An increase in revenue gained from fattening: animals fatten more readily if they are fed treated straw which is then supplemented with cotton seed, cereal bran or hay from legume crops (groundnut, cowpea). In fact, the following occurs:
a reduction in the time required for fattening.
a lower consumption of those supplements most frequently purchased.
a greater ease to sell the animal on the market during the dry season (an optimum liveweight) when the competition can only offer thin animals.
a higher profit margin.
e/ An increase both in milk production and general body condition both of the mother and the calf.
f/ An improvement in fertility levels: after feeding treated forage, cows show more intensely the characteristics of being on heat.
g/ An increased strength and endurance of work animals which, in some countries, have been given priority for being fed treated forage, particularly in the Sahel region (in Niger, 80 % of animals fed treated forage are draft animals) and in South East Asia.
h/ And finally a very revealing and important observation relating to the increased production of manure of better quality by animals fed on treated forage. “They produce more pats which are softer and darker in colour”. This farmer observation accompanies those concerning soil texture which is improved and concerning crop development which is considered more vigorous and productive. The manure from animals eating treated forage has also allowed some farmers to reduce their application rates of chemical fertilizers. This observation agrees with research study results (see § 532).
|Initial weight||Intake (g DM/day)||Average Daily|
|(kg)||Wheat straw||Concentrate||Fish meal||Blocks||Gain (g/day)|
Cases where crop residues remain in abundant quantities are relatively frequent. Unfortunately, these forage resources are often badly managed (with losses, poor storage, burning, …). The treatment presents the occasion to improve their nutritional value and, as a result, the general nutritional state of the animals. It also helps, at the same time, to improve management of these resources.
Table 23 presents a theoretical balance sheet for the nutritional needs for production cattle. Whereas non-treated straw will not even cover the basic maintenance requirements (hence the weight loss which is observed), the same straw after treatment, amply covers these requirements and can go a long way towards providing needs for production.
This is the interpretation made by many farmers interviewed in Niger, Madagascar, etc., … who had never treated their rice straw with urea before. They notice that the general body condition of their animals improves after only three or four weeks.
|Production state of the animal||Requirements including maintenance (1)||Intake||Nutrient supply (2)|
|Maintenance (350 kg liveweight)||2.85||341||5.25||7,00||2.0||210||3.15||700|
|Milk (350 kg liveweight; 4 litres / day)||4.15||689||5.25||7,00||2.0||210||3.15||700|
|Growth (200 kg liveweight; ADG=250g)||2.60||450||3.00||4,00||1.14||120||1.8||400|
|Traction (350 kg liveweight; moderate work)||3.55||570||5.25||7,00||2.0||210||3.15||700|
(1) - N R C, 1976
(2) - Values (g/kg DM) for non treated straw (NT: N × 6.25 = 40, TDN = 380 and a daily consumption of 1.5 kg / 100kg liveweight and, for treated straw (T): N × 6.25 = 100, TDN = 480 and 2 kg / 100 kg liveweight
|DM intake (kg / day)||3.45||3.48||4.20|
|ADG (g / day)||125||303||310|
|Feed conversion (kg of feed / kg gain)||28||11.5||13.50|
Most small farmers only cultivate limited areas under cereals (often less than a hectare) and production rates of straw and cereal stalks are low.
I ha of rice producing say, 3 ton of paddy (in Africa) or 2 ton (in Asia) represents a stock of between 2 and 3 tons of straw, if the average Grain/Straw ratio is 1.
In this case, the straw is generally given in limited quantities in the evening after the animals have returned from pasturing. This will also be the case for the treated straw which will only constitute a supplement (from 3 to 4 kg per day) to the pasture.
Table 25 shows results from an example in Cambodia where for a similar and even modest intake of treated and non-treated straw (3 kg DM/day), the digestibility of the dry matter and the amount of crude protein ingested were respectively, increased by 35 % and multiplied by a factor of 3 (KAYOULI, 1994b). Under similar conditions (see Table 24), other authors have recorded an increase in Average Daily Gain (ADG) of 180 g/day (KHAN and DAVIS, 1981).
Farmers in numerous Asian countries (Bangladesh, Cambodia, Laos, …) and from the Sahel (Mauritania, Niger, …) who endure this type of situation, are unanimous in remarking that liveweight is maintained and body condition improved for their animals, particularly during the dry season.
This beneficial effect resulting from treating the straw is mainly due to the fact that it supplies nitrogenous elements which are missing in the diet and which are needed for cellulolysis of the cell matter (pasture during the day, straw at night); and this despite the fact that the treated straw will not make up more than half the overall daily ration of coarse forage. The effect is also partly due to the digestible energy provided through the supplement.
|Non treated straw||Treated straw|
|Composition and digestibility|
|Crude protein (N x 6.25) (% DM)||3,5||10.3|
|Digestibility of the dry matter (%)||35||46|
|Intake (kg / day / animal)|
|Digestible dry matter||1.05||1.38|
There is no doubt that treating low quality forages is fully justified, whether stocks are great or small. Should stocks be abundant, the farmer will be encouraged to improve management practices.
Apart from perhaps India in Asia and a few special cases in the highlands of Africa, the majority of livestock farmers in these continents do not specialise in either dairy or meat production, rather they seek multipurpose production objectives.
|RICE STRAW (ad libitum)||NON TREATED||TREATED|
|Number of animals||17||17|
|DM Intake (kg/day)|
|MILK PRODUCTION (kg/day) IN|
|ADDITION TO THE CALF REQUIREMENTS|
The herds are of very variable size under these farming systems and produce calves which are suckled by their mothers and from which a few litres of any remaining milk are taken for domestic consumption, occasionally some being sold. The calves may be sold locally for fattening (if there is a local specialist fattening centre and an organised market), fattened on the farm itself or perhaps raised and later trained as draft animals for tillage and transport purposes.
Production levels are modest, particularly as regards the quantities of milk produced by cows, which are not primarily dairy cattle.
All results described by interviewed farmers and shown by studies undertaken at field level tend to agree with those achieved under the more rigorous conditions at experiment station level. The substitution of non-treated forage by that which has been treated translates into increased milk production, improvement to the cow's body condition and to growth of the calf. Schematically, the response tends to be more “dairy” oriented at the beginning of lactation and more “corporal” towards the end of lactation (due to changes which occur in mobilisation/storage of the body reserves during the lactation/gestation cycle of the cow).
Published references are found mainly to refer to experiences in India, Sri Lanka and Bangladesh where cattle farming is directed more towards dairy production, but few relate to Africa. Without referring to all, one may draw out the following points:
Table 26 shows results from a trial in Sri Lanka, described eloquently by PERDOK et al., (1982). The local breed of cows, Gir, were voluntarily fed rice straw which was either untreated or treated and in each case, supplemented with 1.5 kg/day of concentrates; results for the treated straw showed a significant increase in daily milk production (of 1 kg/day), together with increased liveweight gain for the cows (+95 against -266 g/day) and also the calves (257 against 181 g/day).
in another trial, rice straw treated with 4 % urea was offered for voluntary feeding, mixed with 1 kg/day of concentrates: this ration allowed accomplishing a daily milk production of 2.5 to 3 kg whereas the control group, fed with non-treated straw but the same amount of concentrates could only cover their basic maintenance requirements (REDDY et al., 1991).
in India, an increase in daily milk production was recorded of 1.7 kg (5.9 as opposed to 4.2 kg), together with being able to economise by halving the supply of proteins (KUMAR et al., 1991).
in Tanzania, both purebred and crossbred Tanzanian Zebu and Shorthorn gave an increased milk production of some 1 kg/day when fed maize stalks treated with 6 % urea, supplemented with leaves from banana and grass harvested along pathways, together with 2 to 3 kg of concentrates (CHENOST et al., 1993).
One may also mention the experiences and results from the following field experiences witnessed by the authors but which they have only recorded as field notes and mission reports, the records remaining as yet unpublished:
|(a) - Animal production systems|
|- Rice straw treated with 6 kg of urea and 100 kg of water per 100 kg of straw (for 5 weeks)|
|- Malgache Zebu cows or Friesian or Danish crossbreeds - 1 to 5 cows per farmer|
|- Production level: 4 to 8 kg / day in addition to supplying the calf|
|- Grazed during the day along the irrigation bunds and on rice regrowth|
|- supplement: 5 kg of rice straw in the evening with 2 to 3 kg of cassava tubers|
|(b) - Results of the survey|
|Increase in the amount of milk produced in addition to the calf (kg/day additionally)||0– 0.5||0.5 – 1.0||1.0 – 1.5||1.5 – 2.0||2.0||Total|
|Observed on (number of cows)||4||4||12||9||4||33|
|(c) - Nutritional verification:|
|NT||T||Increase(T - NT)|
|Straw DM intake (kg/day)||5||5|
|per kg straw DM||0.40||0.55|
|per kg straw DM||10||40|
Increase allowed by the supplementary intake of UF: 0.75/0.4 = 1.8 – 1.9 kg of milk
Increase allowed by the supplementary intake of DCP: 150/60 = 2.5 kg of milk
(0.4 UF / kg of milk)
(60 g DCP / kg of milk)
taking up milking the cows again (producing between 2 and 3 litres/day) during the dry season by those practising mixed farming at Dioundali, 200 km South of Niamey in Niger, following feeding of rice straw treated with 5 % urea (KAYOULI, 1994a) and also a similar situation on the right-hand bank of the Senegal River in Mauritania (CHENOST, 1995); in both cases, farmers previously would normally stop milking during this period so as to favour the production requirements of the calves.
an increase in milk production recorded in Niger over a four month period which rose from 160 to 300 litres/cow after providing an evening feed ration of treated straw, so supplementing the daily pasture intake.
an increased milk production in Madagascar ranging from 0.5 to 2 litres/day (with an average increase of between 1 to 1.5) for local or crossbred Malgache Zebu cattle fed 5 to 6 kg of rice straw treated with 6 % urea, supplemented with pasture gathered from the bunds and rice shoots (regrowth) together with between 2 and 5 kg of fresh cassava roots (CHENOST, 1993); these cattle were producing from 4 to 8 litres/day of milk, in addition to nourishing their calves (see Table 27). This same Table shows that, starting from a simplified calculation of the estimated energy values of the Digestibility in vitro on the one hand, and from an estimate of the digestible crude protein content on the other, for equal quantities of ingested straw (5 kg in each case), results were as follows:
the increase to the energy value of the straw due to treatment contributes an increase in the daily milk production of between 1.5 and 2.0 kh; on the other hand, the effect of increasing the nitrogen content of the intake produces a milk increase of about 2.5 kg/day.
It is interesting to note that response to treatment as observed in the rate of milk production is greater for these modest production levels than for higher levels (SAADULLAH et al., 1988 and HADJIPANAYOTOU, 1992). This is particularly the case for observations made on farms in Bangladesh where milk production rose above 2 litres/day in addition to suckling calves (SAADULLAH et al., 1988). Expressed in other terms and this confirms the observations presented in Chapter 6, response is optimum for animals of low demand when rations are mainly based on forage. These constitute the “target” animals which should be the first beneficiaries of the treatment techniques.
Many tropical countries practice traditional fattening techniques. These consist of feeding, throughout the dry season, the crop residues left after the harvest such as rice straw, stalks from maize, sorghum and maize, hay from cowpea and groundnut and sometimes, leaves from standing tuber crops; these are fed to the thinner animals which have been separated from the herd, or perhaps bought in specially, these animals being kept near to the house. These residues are supplemented by amounts which vary considerably according to availability and price (from 2 to 5 kg); supplements in these situations most frequently consist of two byproducts, broken grain and bran from the artisanal rice mills and cotton seed from artisanal cotton mills (cotton cake from the larger commercial cotton mills situated in the main towns rarely return to the original producers, despite these being potential buyers).
The animal benefits from this favourable nutritional situation and starts growing again (the classic phenomenon of compensatory growth). The experiences of the mixed farmers from Niger quoted above (see § 731) who had started to use treated in place of non-treated straw for these types of animals, were unanimous in observing:
either, a reduction in the time needed for fattening, all supplements being otherwise the same,
or, the possibility of economising the use of supplements (by up to half), the growth rate remaining the same,
This economy in the use of supplements may be quantified by considering the example shown in Table 28: the ration is based on rice straw supplemented with rice bran and is designed for a Zebu with liveweight of 200 kg with a target growth rate of 500 g/day so as to arrive at a liveweight of 300 kg after 200 days (a growth of 100 kg). An economy of almost half the total amount of rice bran can be made but, in recompense, the farmer must take care to manage his stock of straw which will be ingested in larger quantities now that it has been treated.
Table 11 presents a summary of results from on-station trials and field observations mainly recorded in Asia. These show that for equal amount of feed supplement, treating straw with urea allows one to expect an increase in daily growth rate of 200 g (+/-127 g) as compared to basing the ration on non-treated straw. This increase is, however, very variable, the reason probably originating from variations amongst the particular trials or controls concerning not only the treatment itself but also the supplements.
A recent trial was undertaken in Vietnam with crossbred Red Sindhi x Yellow Cattle which were fed either (I) non-treated rice straw alone, (ii) the same straw but supplemented with molasses/urea blocks or (iii) rice straw treated with a mixture of urea (2.5 kg/100 kg), lime (0.5 kg/100 kg) and salt (0.5 kg/ 100 kg). Interesting results were obtained through supplementing the straw with the blocks (+86 g/day) and with the treated rice straw (+ 172 g/day) although this was undertaken with a reduced urea dosage; feeding the rice straw alone gave a growth rate of 277 g/day (BUI VAN CHINH et al., 1994).
|TDN||N × 6.25|
|Feed composition (g/kg DM)|
|Non treated rice straw||380||40|
|Treated rice straw||450||100|
|Needs for maintenance and growth|
|(average liveweight 250 kg, ADG = 500 g)|
|kg / day||3.50||0.560|
|Feed supplies (kg/day)|
|1. by the non treated straw intake (4 kg)||1.520||0.160|
|by the rice bran intake (4 kg)||2.200||0.320|
|2. by the treated straw intake (5 kg)||2.250||0.500|
|by the rice bran intake (2.5 kg)||1.400||0.200|
|Stock required for 200 days||Straw||Bran|
|Non treated straw||200 day × 4 kg = 800 kg||200 day × 4 kg = 800 kg|
|Treated straw||200 day × 5 kg = 1000 kg||200 day × 2.5 kg = 500 kg|
Few rigorous trials have been reported which clarify the “alkali” effect due to treatment as compared to simply supplementing the straw with an equivalent quantity of urea. Those which have been reported (see Table 29) all show that urea treatment gives better results than merely supplementing the non-treated straw with urea.
It is most important to emphasise this point as there have been many remarks implying that urea treatment offers no advantage over simply supplementing the ration with the same amount of urea. It is now well demonstrated that treatment greatly improves both the digestibility and intake of the forages. The only reasons which might justify such remarks are of two types:
|Animals (Liveweight, kg)||Straw intake (kg DM / day)||Liveweight gain (g / day)|
|Cattle (130–140)||1.7||1.7||1.9||35||75||110||Saadullah et al., 1981 b and 1982|
|Cattle||2.1||2.3||2.9–3.0||103||213||237–310||Perdok et al., 1984|
|Cattle (75–78)||2.2||2.4||207||297||Saadullah et al., 1983|
|Cattle (166–178)||3.4||3.9 – 4.8||141||207–336||Kumarasuntharam et al., 1984|
|Cattle||2.8||4.0||111||246||Jaiswal et al., 1983|
|Cattle (177–196)||3.6||4.3||304||598||Promma et al., 1985|
NT - non treated
SU - Supplemented with urea
T - treated with urea
either, the treatment has not been correctly carried out,
or else, the treated forage has not been distributed under nutritional conditions best adapted for ensuring its utility (too high amounts of concentrates, particularly if it is rich in cereals).
Large ruminants are used as draft animals for cultivation tasks and transport in most developing countries, in Asia, Madagascar, the sorghum and millet regions of Africa, …
Measurement of work efficiency of these animals requires sophisticated methods and equipment and methods for judging effects in the field can only be subjective. Despite this observation, the small farmers who have given treated straw to their animals all remark on the apparent improvement in their working efficiency and that they maintain better body condition throughout the work season. They can even sell their animals at a higher price at the end of the season as they are then in better condition than before. Cattle merchants sometimes buy these animals at the end of the season at low prices (because they are exhausted and in poor condition) so that they can allow them to recover or keep them for fattening.
Under medium intensity working conditions, non-treated straw only covers about half the animal's needs (see Table 30) and there is a high deficit of energy and protein. This causes reduced energy available for work and a drop in body condition. The animal does not work as well, is slower and this causes delay in the cultural operations of seeding and rice transplanting. It is therefore necessary to supply them with supplements consisting of rice bran, cotton seeds or even cassava tubers (South East Asia and Madagascar). The example illustrated in Table 30 shows a total requirement of 360 kg of bran over a 4 month period. When the straw is treated, this alone is almost sufficient and only 60 g/day of bran will be needed over the same period. The amount of treated straw required (7 kg/day over 4 months or 840 kg) is more than the amount of non-treated straw which would otherwise be needed (5 kg/day or 600 kg in total).
The economic implications may also be readily calculated and so the relative interest judged concerning whether or not to treat the straw, based on the respective prices of straw, urea for treating and bran for the supplement.
Such a study was undertaken in Takéo Province in Cambodia and it illustrates well the efficiency of treatment and of the supplement (KAYOULI, 1994b): whereas the farmer only managed to use his draft animals previously for some 2 hours when fed on non-treated straw, he obtained 4 hours of work from the same animals after they had been fed treated straw supplemented either with multinutrient blocks or with 0.5 to 1.0 kg of rice bran.
In countries or regions such as North Africa, the Near East or in China and for peri-urban livestock production in developing countries where production systems are more intensive, it is also possible to incorporate the use of treated forage into the feeding system.
|TDN (kg)||N × 6.25 (g)|
|Requirements for maintenance+work||3.55||570|
|Nutrient supplies from straw|
|NT (5 kg / day)||1.90||1.65||200||370|
|T (7 kg / day)||3.20||1.20||700||None|
|Amounts of bran needed to compensate for deficit (kg)|
|Deficit||Bran (kg/day)||Deficit||Bran (kg/day)|
Nutritional value of the straw and bran:
|TDN (g/kg)||N × 6.25 (g/kg DM)|
|NT = Non treated straw||380.000||40.000|
|T = Treated straw||450.000||100.000|
The performance expected, in terms of milk and meat production, is considerable. Straw and forage, even if treated, will not cover more than the basic maintenance and modest production needs of the animal and results can be very variable; supplements will have to be provided in significant quantities.
The aim must be, as already described above under § 61, to remain within the nutritional limits so as not to constrain cellulolysis. These considerations become more important as the proportion of supplement in the diet increases (the reader should again refer to these nutritional limits discussed above under § 612).
One should recall the case of livestock production as practised in North Africa where it is closely integrated to cereal production and where straw constitutes a very useful forage resource. It would be more logical in these systems to feed treated straw to those animals with only moderate needs, such as heifers at the end of growth and dry cows, the target animals. The good hay (annuals such as vetch/oats in North Africa) should be reserved for the high production cows with efforts made towards improving hay quality (harvest date, quality of the conditioning process and storage conditions).
References from the temperate regions are numerous concerning growing animals and dairy cows, privileged to receive treated straw. A review article allows one to summarise that for equal amounts of feed supplement, the increase in Average Daily Gain (ADG) is of the order of 200 to 300 g/day and, for equal performance rates, it is possible to reduce the amount of supplement by 1.5 to 2.0 kg (DEMARQUILLY et al., 1987).
The Chinese experience merits attention both from the development and nutritional points of view. It constitutes a remarkable experience concerning the use of treated straw for meat production:
China produces some 400 million tons of grain and disposes of over 500 million tons of crop residues (both straw and stalks).
An extension programme concerning urea treatment of these residues was started in 1987, mainly in two provinces of central China. Following the success which was achieved, this technique was generalised through successive phases of a joint project undertaken in 1990 and 1992 by UNDP and the Chinese government (GUO TINGSHUANG et al., 1993).
11 million tons of straw, affecting some 3.3 million farmers were treated in 1993 for feeding to male “Yellow Cattle” after weaning up until they were slaughtered at a weight of 400 to 500 kg, then being aged between 18 and 24 months.
This system was first introduced in the period 1988/1990 for small farmers with an average land holding of 0.5 to 1 ha and who were producing wheat, barley, maize and cotton.
The straw is treated with 5 kg of urea and 30 to 80 kg of water per 100 kg of straw in cement pits which are covered over with plastic for 3 weeks.
The results were presented and critically discussed during the Conference titled “Increasing livestock production through utilization of local resources” held at Beijing in 1993.
The animals (bullocks of 180 kg at the start) are fed ad libitum the treated straw together with 1 to 3 kg of cotton cake which constitutes the only supplement. They are slaughtered once they reach a liveweight of 450 kg. Trials have been undertaken in order to gauge the response of the animals to the level of the feed supplement both from the animal production and economic viewpoints. Table 31, together with a synthesis of this work prepared by DOLBERG and FINLAYSON (1995), show that the daily weight gain responds asymptotically to the amount of cotton cake given. The curve tends to flatten out at about 800 g/day representing a supplement quantity of 2 to 2.5 kg/day of cake per animal.
Considering the relative local costs of urea and the cake, it seems that a ration of between 1 and 2 kg/day of cotton cake represents the best technical/economic compromise. These recommendations are now being extended in the two provinces.
This example well illustrates the possibility of taking full advantage of local forage resources through a combination of using treatment techniques and appropriate amounts of feed supplements.
Many farmers have simultaneously used for the same animals, both forage treated with urea and multinutrient blocks. They note better endurance of the animals and a more rapid regain of weight (DALIBARD; 1994).
The authors have asked many farmers practising mixed farming which of these two techniques they prefer and most reply that both methods are useful and that they complement each other. The tendency is to favour treated straw which, according to them, “fills up” the animal. Treatment is perfectly justified in their eyes for certain categories of animal (for draft and meat production) because results are more rapid and higher, whilst they consider the blocks more as “stimulating the appetite”, often qualifying this to describe the blocks as “medicine” and as better adapted for rangeland livestock production (notably as practised by the nomads).
Women farmers, such as those in the Sahel, frequently look after important numbers of small ruminants. The physical exertion involved in treating forage is more difficult for them than the fabrication of multinutrient blocks. In these countries, the women are sometimes themselves involved in making the blocks, even commercialising them.
When one is looking for higher levels of production, the use of multinutrient blocks is no longer sufficient. It is then necessary to supply the animals with appropriate “additional” supplements allowing these goals to be reached but without compromising the digestion of the low quality forages.
As has already been described, these supplements must be rich in proteins having a very low solubility. For example:
cake from groundnut or cotton, cotton seed and, above all, fish meal,
other locally available products such as cereal bran,
and finally, certain forages: hay from food crops, leaves and pods from forage bushes.
These aspects are well illustrated in the results presented in Table 22 (TIWARI et al., 1990).
There is no doubt that multinutrient blocks provide an efficient means for improving the nutritional value (intake and digestibility) of straw and low quality forages. They allow a reduction to the weight loss generally registered in tropical countries during the dry season. One might even register modest increases in milk production and weight gain in certain cases. In order to go beyond a mere maintenance diet for the animal, one must have recourse to appropriate supplements which associate with the beneficial action of the blocks through synergy (rather than being antagonistic).
The use of minimum (catalytic) supplements with low quality forages, where a typical example comprises the multinutrient blocks, represents a first step which allows one to safeguard the animals and to limit the weight loss commonly experienced during the dry season in tropical countries. This technique might even allow modest gains in weight.
To advance beyond simple maintenance of the animal, one must resort to the use of appropriate supplements which will associate in a synergetic manner with the beneficial action of the blocks.
It is also possible to revert to urea treatment of the forage when the livestock farmers observe that this is better when compared to using the blocks. It is now well established that treatment with urea gives better results than simply adding the same amount of urea to non-treated straw.
Treating straw and low quality forages for which supplies are limited is also interesting because, once treated, this fodder constitutes a supplement for the natural pasture consumed during the day. When low quality forages are readily available and form the basic ration for the herd, treatment becomes even more interesting. It also encourages the farmer to manage forage stocks better than previously.
For animal production systems wishing to advance beyond simple maintenance, forage treatment constitutes the next stage towards improvement of production levels of the herd. Production response to treatment will be much more marked if the basic rations consist mainly of poor quality forages. Such rations are thus better used for those animals which have only moderate requirements, the “target” animals which should be the prime beneficiaries of the treated material. In addition, treating with urea allows:
either a reduction in the amount of supplement supplied, whilst still maintaining the same performance of the animal. This is particularly appreciated by the mixed farmers and rice farmers who notice their draft animals maintain their work efficiency and general body condition;
or, when feeding the same amount of supplement, an increase to the daily weight gain (approximately an additional gain of 200 g/day) and to the amount of milk produced in addition to that suckled to the calf (an additional 1.5 to 2.5 litres/day), each compared to when non-treated straw is fed.
These increases are very variable due to variations which occur concerning the quality of the treatment and above all, to the condition of the supplementation.
At the higher rates of supplement supply which are required for more intensive production systems, one must be particularly vigilant to ensure that these continue to further optimize the use of the treated material and do not effectively rub out any benefits of the treatment.
This is the risk run in production systems such as those in North Africa, the Near East and China, or even more so in the dairy and fattening zones surrounding major towns in developing countries. Animal production systems are more intensive and errors can be made concerning both the quantities and nature of the supplements. In this respect, the Chinese example well illustrates how to perfectly optimise the use of local forage resources.
In the intensive animal production systems integrated with cereal production where straw, despite its modest nutritive value, constitutes an indispensable forage resource, it becomes even more logical to feed any straw which has been treated to those animals having only modest needs, such as heifers at the end of their growth period and cows at the end of lactation, the “target” animals, and to reserve the best forage for the highly productive cows.
There is no doubt that low quality forages, whether they are treated or not, are far better utilised when production levels of the animals being fed are modest or, in other terms, when the proportion of this forage in the ration is higher.