Chapter 3 Sugar cane

Sugar cane (Saccharum officinarum L.) is a tropical, perennial grass that tillers at the base to produce multiple stems, three to four metres high and approximately five centimetres in diameter. Its composition varies depending upon the climate, soil type, irrigation, fertilizers, insects, disease control, varieties, and the harvest period (Meade and Chen, 1977). The air-dry (AD) “millable” cane stalk, approximately 75% of the entire plant, contains 11–16% fibre, 12–16% soluble sugars, 2–3% non-sugars, and 63–73% water (Dillewijn, 1952). Although the average yield of “millable” cane is 60 t/ha/yr (FAO, 1992a), this figure can vary between 30 and 180 tons per hectare.

Sugar cane can be used as a major feed resource for most livestock, either by the small-scale farmer who grows between one and five hectares and has several pigs, some ducks and small ruminants (Preston and Murgueitio, 1992), or by the sugar factory that manages up to 10,000 ha and needs to diversify and/or produce food for its workers (FAO, 1988). In fact, one group of researchers in Puerto Rico has promoted the idea of “energy” cane, using the entire crop to exploit its biomass potential by bringing the whole plant into the factory to be used for raw sugar, animal feed and energy. They maintain that the growth potential of sugar cane, long thought of only in terms of the “millable” stem for sucrose, has been “underrecognized and underutilized”, and that the production of up to 286 t/ha of sugar cane biomass is possible (Alexander, 1988).

Sugar cane, reportedly one of the most efficient plants to use solar energy to convert carbon dioxide and water to carbohydrates, is presently undergoing a “user-friendly” metamorphosis with regard to its potential both as an industrial raw material and for feeding all kinds of livestock (Table 3.1), not only pigs, the objective of the remainder of this chapter.

PRODUCTION AND TECHNOLOGICAL PROCESSES

Sugar cane is presently grown in more than 100 countries. The following figures refer to “millable” cane (Table 3.2).

a NIOM = non-identified organic matter.b SCJ = sugarcane juice (non-industrial).c water is added during the extraction process, the real extraction rate is 82–86% of total available juice in millable cane which is 72–75% of totaljuice; d dried for storage, contains 2–3% moisture

Source: FAO (1992)a; * 1 000 mt of “millable” cane

THE PRODUCTION PROCESS FOR INDUSTRIAL RAW CANE SUGAR.

The harvested cane stalks are sent to the factory where they are crushed by means of a series of three to six “3-roller-mills”. Water is added to improve juice extraction; this increases the weight of the diluted juice to between 90 and 96% of the weight of the milled cane. The extracted sugar cane juice is immediately subjected to three processes: liming, heating and settling, which is carried out in sedimentation tanks, called clarifiers. After two to three hours, the resulting “clarified” juice is sent to the evaporators where it is concentrated to a syrup.

Bangasse, a fibrous residue of 50% dry matter, is screened through rotary or vibrating sieves to sift out finer particles called bagasse pith. The pith is used to filter a mud-like sediment produced in the clarifiers which, after processing, is called “filter-press mud” or“filter-press cake”. Most of the remaining bagasse is burned in the mill to produce steam and electricity to operate the factory.

The syrup, meanwhile, undergoes a progressive series of steps in the vacuum pans to produce industrial raw sugar. A and B, combined to form commercial raw sugar non-commercial raw sugar C (low-grade or crystal seed-sugar) and final or C molasses. The final or C molasses is pumped out of the mill. Approximately two-third's of the C sugar (crystal seed-sugar) is dissolved and incorporated in the original syrup. The A and B commercial raw sugar can be bagged or sent to the refinery.

Raw sugar, processed to white or refined sugar, produces a residue called “refinery final molasses”, similar to C molasses. The amount is insignificant and generally if the refinery is part of the sugar factory it is simply deposited in the C molasses tanks. The entire process for the production of raw sugar, from start to finish, requires 20–28 hours.

PRODUCTION ALTERNATIVES FOR A SUGAR FACTORY

The following diagram shows the five alternatives, together with average yields, when 100 tons of millable cane enters a traditional raw sugar factory (Figure 3.1.). Four tons of bagasse has been considered the thermal equivalent of one ton of fuel oil. This fact has been emphasized due to the potential use of bagasse to generate electricity.

Fig. 3.1. Schematic representation of 100 tone of millable cane in a sugarmill (Pérez 1990).

The first alternative is the production of diluted cane juice of 15 to 19% dry matter, depending on the stage of the harvest and the amount of water added during the grinding process. If the sugar mill is used exclusively to produce diluted juice then the amount of surplus bagasse would be between 50 and 60% of the total amount needed to produce the vapor for a traditional factory. In a non-industrial operation (simple crusher), 100% of the pressed cane stalk (bagasse), together with a significant amount of residual cane juice, would be available for small ruminant feeding (Preston, 1990a; Vargas, 1993), as fertilizer or a fuel (Preston and Murgueitio, 1992).

The second alternative is the production of high-test molasses which is clarified and partially inverted concentrated cane juice. This option would save between 25 and 40% of available bagasse, which as earlier emphasized might be used to generate electricity. High-test molasses can completely replace cereals in liquid diets for pigs and has been used for this purpose when market conditions and/or tariffs have blocked the commercialization of raw sugar.

The third alternative is the production of raw sugar A, about 77% of available raw sugar, together with type A molasses. This alternative could save between 20 and 35% of the total amount of bagasse produced. If stored, the A molasses would have to be partially inverted to avoid crystallization. Inversion requires the addition of 0.5 kg/t of hydrochloric or sulphuric acid followed by mixing for 30 minutes, and finally neutralization with lime. Type A molasses still contains a considerable amount of commercial raw sugar, therefore, although it has been increasingly promoted for the experimental feeding of pigs (see below) it has not, as yet, been utilized as an important energy resource for commercial livestock production.

The fourth alternative is the production of commercial A and B raw sugar, some 89% of the total available raw sugar, and B molasses which does not frequently crystallize. This option saves 10 to 30% of the total bagasse needed to run the factory and was the alternative first developed in Cuba for commercial pig feeding systems (see below).

Figure 3.2. Schematic representation of the internal production of “crystal seed-sugar”.

The fifth alternative, that which is normally done in a traditional raw sugar factory, is the production of A and B commercial sugar and non-commercial C sugar, also known as low-grade or crystal seed-sugar, and C or final molasses. Low grade sugar has been studied as a complete substitute for cereals in fattening rations for swine (see below). The removal of excess crystal seed-sugar would improve the overall thermal balance in a traditional raw sugar factory, where normally only 5 to 20% of the bagasse is not needed to produce vapour. The only drawback to using C sugar as a feedstuff would be the need to remove some water; at this stage it contains between 2 and 4% moisture. However, this could be easily remedied by mixing the crystal seed-sugar immediately upon leaving the centrifuge with the other dry components of the ration (Fig. 3.2).

PRODUCTION ALTERNATIVES FOR SUGAR CANE CRUSHERS

Approximately 12% of all raw sugar for human consumption is produced in simple sugar cane crushers (FAO, 1992). These crushers could be used to obtain juice to feed pigs and other livestock. Cane juice, extracted in this way, contains approximately 10 to 13% more total sugars compared to factory juice, principally because no water is added. However, because less pressure is applied and no water added, the extraction rate is only half that of a sugar factory (Table 3.1).

OPTIONS FOR USING SUGAR CANE AS FEED FOR PIGS

Development of a sugar cane juice feeding system

One of the first countries to publish promising results related to cane juice as a partial or complete replacement for cereals in swine diets was Brazil (De Felicio and Speers, 1973). Subsequently, research in Mexico (Preston, 1980; Mena, 1981), and further studies in the Dominican Republic (Fermín, 1983; Fernández, 1985), alerted other tropical countries to this new development (FAO, 1988). In fact, Mena (1987) reported that by the end of 1986, ten thousand pigs in the Dominican Republic had been fattened on cane juice as a substitute for imported maize.

In Mexico, the initial investigative work on the use of sugar cane juice for pigs used fortified soya bean meal to meet protein requirements as established by the National Research Council (NRC, 1979) at that time. For that, three groups of pigs with an average initial weight of 40, 50 and 60 kg were fed until 90 kg liveweight free-choice cane juice and 0.77, 0.81 or 0.96 kg/day of a 40% crude protein supplement. The pigs in each group, until slaughter, consumed 308, 324 and 384 g of protein daily, an average saving of 20% of the then prevailing NRC requirement (NRC, 1979). The control diet was a mixture of sorghum and soya bean meal. The average daily gains and feed conversions of the pigs on the cane juice treatments were 20 and 25% superior to that of the cereal control, respectively (Mena, 1981).

In the Dominican Republic, Estrella et al. (1986) promoted a cane juice feeding system in an attempt to produce lard, normally imported. For that study, three groups of finishing pigs were fed fresh cane juice and different amounts of a protein supplement: 180, 270 or 360 g/day. Surprisingly, the pigs in each group grew at approximately the same rate (Table 3.3: Exp.1). Following that, similar trials were carried out in Colombia using concentrated scums, a waste product from the production of pan sugar. The results (Table 3.3: Exp. 2) supported those of studies previously cited from Mexico and the Dominican Republic, that pigs fed ad libitum sugar cane juice grew well, if not optimally, with approximately one-half the amount of protein provided in cereal feeding systems (Moreno et al., 1989, cited by Sarria, 1990).

To emphasize this essential point: the daily amount of protein currently recommended by NRC for pigs between 50 and 100 kg, fed ad libitum a 13% crude protein, air-dry, cereal diet, is 404 g. The expected average daily gain is 820 g; the air-dry feed intake is calculated as 3.11 kg and the air-dry feed conversion as 3.79 (NRC, 1988). The figures for daily feed intake and feed conversion, adjusted to 90% dry matter, would be 2.8 kg and 3.41 respectively (Table 3.3).

In conventional cereal diets, 50% of the protein needs are supplied by low amino acid-profile cereals, equivalent to approximately 70% of the formula. The protein requirement is achieved through animal or vegetable protein supplementation, at a level of about 30%, the remaining portion of the diet. However, in the case of cane juice diets, all of the protein must come from an outside source, which could mean a superior amino acid balance (Speedy et al. 1991).

Sources: ^a NRC (1998); ^b Estrella et al. (1986); ^cMoreno et al. (1989), cited by Sarria (1990)

A “sugar cane juice feeding system” has developed: it refers to growing/finishing pigs fed free-choice sugar cane juice and a restricted amount of high-quality protein (approximately 200 g/day) generally obtained from 500 g of a soya bean meal-based supplement, preferably fortified with minerals and vitamins (Moreno et al., 1989; Preston, 1990b; Sarria et al., 1990). This same feeding system has now been successfully promoted in Southeast Asia (Van and Men, 1992) and in Africa (Speedy et al., 1991). In Cuba, apart from soya bean meal, 500 g of dry torula yeast has been used (Table 3.4).

^* best gains for 32,000 pigs at 5 different locations fed 0.8 kg/day soya bean meal and free-choice cane juice

Fresh sugar cane juice: farrow-to-finish herd

One of the first references to a swine reproductive herd, fed either fresh sugar cane juice and a restricted protein supplement or a cereal-based commercial ration, referred to the performance of both gestating and lactating sows (Estrella et al., 1984). The confirmed pregnancy rate (85.7 vs. 92.0%) and the piglet average birth weight (1.38 vs. 1.47 kg) was higher on the cane juice feeding system, whereas the average number of live piglets born per litter was lower (8.28 vs. 10.09). Similarly, Piña (1988), reported stronger, more vigorous piglets at birth, and sows that produced more milk and lost less weight during lactation when one month prior to farrowing fresh cane juice (7 kg/day) was added to their other rations.

In Cuba, a 300-sow, farrow-to-finish herd, with a daily average of 3,000 pigs was fed factory-produced fresh juice during the cane harvest season and diluted syrup-off or B molasses during the non-cane season. The protein supplement was soya bean meal (Table 3.5). After a period of six to eight months the following differences in the reproductive herd production parameters were noted: an 8 percent improvement in the farrowing rate (natural service); an increase in the average number of live births per litter (8.6 to 9.3); an increase both in the average live piglet birth weight (0.9 to 1.3 kg) and the 33-day weaning weight (5.0 to 6.8 kg), and most importantly, an average reduction of five days in the weaning to service interval, one of the most difficult indices to improve in a swine reproductive herd, particularly in the tropics. With respect to the productive herd, the average liveweight for age at slaughter increased monthly, during a period of four months, from 79, 83, 94, to finally 102 kg at six months (MINAZ, 1990). This same final liveweight for age on a sugar cane juice feeding system, 100 kg at six months of age, was also reported in the Dominican Republic (Piña ,1988).

The 300-sow, farrow-to-finish herd referred to in Table 3.5 required approximately 20 tons of juice per day. As earlier mentioned, when sugar factory juice was unavailable due to shutdowns for maintenance, prolonged rainy periods, or during the non-harvest season, either diluted B molasses or syrup-off, mixed with three parts water and called “reconstituted cane juice” was used. It was observed that in order to optimize the seasonal opportunities for factory-produced juice, the reproductive herd might be bred to farrow mostly at the beginning of the dry, cane harvest season. This would allow for the majority of pigs to be fattened on the fresh juice, with slaughter at the end of the harvest. In this way, only a skeleton reproductive or maintenance herd would have to be fed during the wet, non-cane season and this could be more easily accomplishied using “reconstituted cane juice”. The unusual growth potential of pigs fed sugar cane juice, between 650 and 700 g/day, as opposed to approximately 500 g/day for most types of molasses systems could mean a weekly net saving of 0.75 kg of protein supplement per head (see Tables 3.13, 3.15).

The feed calculation for a 300-sow, farrow-to-finish unit is presented in Table 3.5.

Source: Pérez (1993); ^a fresh or reconstitued juice; ^b fortified soya bean meal or torula yeast; ^c“soya-sugar,” a 16% CP in DM seedsugar-based dry ration for piglets and weaners to 60 days (see 3.3.3.3); ^dbecause the gestating sows receive 14 kg during last month, use 11 kg for calculation; protein supplement only

An analysis of the data shows that:

• The annual, herd-average dry matter feed requirements are: 1693 t (the soya-sugar and protein supplement contain 90% dry matter; the juice contains an average of 18% dry matter).

• The daily, herd-average air-dry feed needs are: 0.2 t soya-sugar, one ton of protein supplement and 20 tons of juice.

• Each sow and all progeny, generally referred to as the “sow-reproductive-unit”, consumes annually, in air-dry: 1.2 t protein supplement and 24 t of cane juice. Theoretically, if this 300-sow, farrow-to-finish herd produced 400 t liveweight yearly, each ton of liveweight would require in air-dry: 0.91 t protein supplement and 18 t of juice.

• The herd-average dry matter feed conversion is 4.23, that of the productive herd is calculated as 3.42.

• The daily herd-average air-dry feed intake is: 0.38 kg protein supplement and seven kg of cane juice. The calculated average daily gain from farrow-to-finish is 490 g (See Table 1.5).

For pigs unaccustomed to a sugar cane juice feeding system, the growing/finishing period might require three to four additional weeks. This is partly due to the need to adjust to the new diet. The following data (Table 3.6) suggest that each pig would require 60 kg of protein supplement and 1.3 t of juice. In either case, the daily protein supplement should preferably be given in two equal portions (Ly and Muñiz, 1979; Cervantes et al.. 1981).

Source:adapted from Preston and Sansoucy (unpublished data)

Sugar cane juice generally ferments within 12 hours, however, it can be preserved for up to three days using either 0.01 to 0.06% formalin (formaldehyde at 30% concentration) or sodium metasilicate at 5 to 7 g/l (Larrahondo and Preston, 1989), and or up to seven days with 0.15% sodium benzoate (Bobadilla and Preston, 1981). Mena (1988) recommended a 40% formaldehyde solution used at the rate of 0.04 v/v, while Duarte (1981) reported using 28% of aqueous ammonia wt/vol at 1.5 percent. Due to the high cost of chemical preservatives and the need to preserve fresh juice, particularly over the weekend, the use of certain macerated leaves have been studied (Larrahondod and Preston, 1989).

Concentrated sugar cane juice (sugar cane syrup)

For small-scale cane producers, who perhaps raise one or two pigs and have access to a cane crusher, the idea of feeding sugar cane juice is attractive but often too time consuming. Two pigs require 20 kg of juice daily and, although this amount could be obtained from 50 kg of clean stalk, the daily effort to cut, carry, perhaps hook up the water buffalo or oxen, or start an engine, to grind such a small amount of cane often negates the practicality of the entire feeding system. Sometimes a farmer has access to a local crusher and only needs a way to preserve some juice. An FAO Technical Cooperation Project in the Philippines found that some farmers preferred to evaporate (boil) the fresh juice, place the resultant syrup in a covered drum alongside the pig pen and reconstitute this syrup with three parts of water whenever the pigs needed to be fed (FAO, 1991).

In a feeding trial to compare the performance of pigs given 0.5 kg of soya bean meal daily and either C molasses, fresh muscovado scums (see below) or concentrated cane juice (reconstituted), most farmers defended the concentrated cane juice system. The C molasses had to be purchased and muscovado scums were available only six months of the year, besides, most farmers preferred to feed them to their water buffalos. For these farmers, an average daily gain of 450 g with concentrated juice/soya bean meal was an excellent system considering the initial liveweight (Table 3.7) and the fact that growth performance was double that obtained on the previous diet of kitchen scraps and forages.

Source:FAO (1991)

Protein-enriched (fermented) sugar cane juice “Protein-enriched” sugar cane juice was first described by Diaz et al. (1992). Fresh cane juice was fermented with one percent urea during 12 hours. Oxygen was incorporated at hourly intervals and formaldehyde was added (2 cc/kg) to preserve the fermented product. It was reported that the fermented juice of 10% dry matter contained 22% crude protein and 13.0 MJ of digestible energy/kg, both in dry matter. Weaned piglets were used to compare restricted feeding systems in which 20 or 30% of protein-enriched cane juice replaced ground wheat (Table 3.8). The authors concluded that the poorer results from the experimental diets might have been due to a lack of fish meal. They also stated that certain symptoms of drunkenness were probably related to the formation of alcohol due to inadequate fermentation.

Source: Diaz et al. (1992); ^* all diets contained 20% rice polishing and different proportions of micro/macro elements; ^** contained 8.7% fishmeal and 2.7% yeast

CANE MOLASSES C molasses has been recommended as an additive to improve the palatability of dry rations, and particularly in cane-producing countries, as an addition to concentrate or swill-based rations at levels up to approximately 30 percent (Buitrago et al., 1977; Preston, 1982). Higher levels have generally not been recommended. The reasons have been; difficulties in handling and mixing; loose feces associated with diarrhoca; dirtier animals and floor pens, and most importantly, an increasingly inferior feed conversion as higher levels of molasses were used (Preston et al., 1968; Velázquez, 1970; Castro, 1976). In summary, certain physiological constraints inherent in C molasses support poor pig performance (Chapter 1).

The fact that large ruminants in Cuba had been successfully fed diets in which C molasses made up 70% of total dry matter (Preston et al., 1967) led to the experimental (Velázquez et al., 1978), and finally commercial practice (MINAG, 1982) of the use of high levels of C molasses for all categories of swine (Table 3.9). This was followed by the first use of another type of molasses, type B, for wide-scale, commercial pig production (Perez et al., 1982; Pérez, 1988).

^aconverted from C to B molasses in the 1980s; ^b100 thousand sows and 500 thousand grower/finishers; ^cprocessedorganic wastes, molasses and water (20%DM);^dcontains 36%DM

There have been many attempts to ameliorate certain of the aforementioned negative effects associated with feeding pigs high levels of C molasses. For example, Brooks and Iwanaga (1967) proposed the use of bagasse pith and fat, while Preston et al. (1968) suggested the addition of raw sugar. Combinations of high-test and C molasses were studied by Marrero and Ly (1976); in the end, they questioned its “doubtful practicality”. Castro and Elias (1978) even recommended using low levels of the mineral zeolite.

Molasses, commonly used as a source of energy, contains approximately 80% of the energy of cereals (Table 1.1). It is practically free of fat and fibre, has low nitrogen content and the amount of ash fluctuates between nine and thirteen percent of dry matter. The nitrogen-free-extract, the main fraction representing between 87 and 95% of total dry matter, is composed of a mixture of simple sugars (62 to 70%) and non-identified organic matter (19 to 24%). The latter has an apparent digestibility of only 51 percent (Ly 1989).

According to the results of several recent studies, it is the increasing amount of this non-identified organic matter in each successive type of molasses, from A to C, that determines the nutritional value of molasses. The amount (% dry matter) of this substance in each type of Cuban molasses is: high-test, 4 to 6%; A molasses, 8 to 14%; B molasses, 12 to 17%; and C molasses, 19 to 24% (Table 3.1). This could be partially related to the fact that mechanically-harvested sugar cane, which in the case of Cuba represents 70% of total cane, contains a higher level of extraneous material which is reflected in the molasses.

In addition, during the process of producing industrial raw sugar, various chemical substances are added, such as; electrolytes, formaldehyde, sulphur dioxide, hypo-chlorides, sodium bi-sulphite, as well as several tenso-active compounds. The concentration of these substances, which increases from A to C molasses, might possibly affect metabolism, and therefore, swine performance.

During 20 years, researchers, mostly from Cuba, have systematically studied the performance of pigs fed high levels of molasses (Figueroa and Ly, 1990; Diaz and Ly, 1991). As an example of their hypothesis, finishing pigs fed a daily average of 2.75 kg of dry matter, particularly where C molasses constituted 60% of the ration, received 14% of their daily ration in the form of non-identified organic matter. A further 10% of ash in the C molasses would mean that 20% of the daily ration was non-identified organic matter and ash. Undoubtedly, the performance data presented in Tables 3.13 and 3.15 reflect this situation.

It was finally decided that from the point of view of both animal and sugar mill performance, it would be better to change to B molasses. This meant that in 1989. over 400,000 t of B molasses were extracted for pig production from 37, of the then functioning 156 sugar mills, and C molasses was left for ruminants. The following description of the study of different types of molasses for pig feeding attempts to focus on this most interesting experience.

Integral molasses

Integral molasses is produced from unclarified sugar cane juice which has been partially inverted to prevent crystallization, then concentrated by evaporation to approximately 85% dry matter. Because unclarified juice is used, the evaporative process produces heavy encrustations and scum deposits that can lead to frequent mill breakdowns. Velázquez and Preston (1970) compared integral and high-test molasses as basal energy sources for pigs; they used two levels of fishmeal. There was no significant difference in feed conversion between energy sources, and it was concluded that the lowered growth performance with integral molasses might have been due to a reduction in voluntary intake. This hypothesis confirmed an earlier observation by MacLeod et al. (1968) that the lack of difference in average daily gain between two protein levels in high-test molasses diets (12.6 and 16.2%) might have meant that when fishmeal was used as a protein supplement, the protein requirement was lower compared to that of a cereal feeding system (Table 3.10).

High-test molasses

High-test molasses is clarified, partially inverted, concentrated cane juice from which sucrose has not been extracted (Table 3.1). Perhaps for this reason, and also because in most cane sugar-producing countries pig production has remained independent of the sugar industry, the commercial use of high-test molasses for feeding pigs has not been practised.

Source: Velázquez and Preston (1970); ^* all diets contained 3% Saccharomyces yeast and 2% macro/micro elements

Recently, Pérez (1993) suggested that one way to maximize protein efficiency for the production of pigs would be to use fresh juice during the cane harvest season and diluted high-test molasses during the non-cane harvest season. The data in Table 3.11, particularly the superior results of high-test molasses as the only energy source, support this idea: the substitution of only 15% high-test molasses by C molasses reduced the average daily gain by 15% (almost 100 g/day), as well as increased the dry matter feed conversion by more than five percent. High-test molasses, compared to C molasses, contains a minimum of non-identified organic matter; this must favor the digestibility of the diet (Chapter 1), and thus the dry matter feed conversion.

Source: Marrero and Ly (1976); ^* all diets contained: 21% fishmeal, 2.5% saccharomyces yeast and 1.5% mineralsand vitamins.

A molasses

One of the first references to the use of A molasses in animal feeding referred to its use in processed swill for fattening pigs where it was compared to C molasses under commercial conditions. A mixture in dry matter of 40% processed swill and 60% type A molasses produced an improvement of 15% with respect to final liveweight (Pérez, 1975). Following that trial, A and B molasses were compared to C molasses under experimental conditions, where the different types of molasses represented 69% of dictary dry matter. The protein supplement was a mixture of fish meal, soya bean meal and torula yeast. The average daily gain for three groups of pigs of average initial liveweight of 25 kg fed the A, B and C molasses was: 638, 715 and 586 g/day, respectively. The higher concentration of sugars and the lower concentration of ash and non-identified organic matter were indicated as the factors responsible for the improved performance of the A and B molasses diets (Figueroa et al., 1983).

A total of 160 pigs with an average initial liveweight of 25 kg was used to compare the performance of growing/finishing pigs fed four types of cane molasses: high-test, A, B and C molasses produced in the same factory (Cervantes et al., 1984). The sugar factory also produced torula yeast cream. The diets were a mixture of approximately 70% molasses and 30% torula yeast cream in dry matter (Table 3.12). The authors concluded, that “the results pointed out the disadvantage of continuing to use C molasses for pigs ”.

Source: Cervantes et al.,(1984);^* all diets contained 0.4% of salt and 0.4% of micro/macro elements

In Victnam, A molasses was used at an air-dry level of 55% to replace a mixture of broken rice and rice bran for pigs of between 50 and 80 kg. The average daily gain was slightly lower (551 vs. 538 g), as was the daily dry matter feed intake (2.06 vs. 1.84 kg), however, the dry matter feed conversion was better (3.74 vs. 3.42) for the group fed A molasses (Van and Men, 1990). In a second experiment, either A molasses or sugar cane juice completely replaced cereals for pigs weighing between 9 and 80 kg. The average daily gain (g) and dry matter feed conversion on the A molasses, cane juice and the cereal control treatments were, respectively; 430, 4.02; 495, 3.88 and 473 and 3.33 (Van and Men, 1992).

B molasses

In Cuba, over a period of 15 years, a pig feeding system gradually developed based on processed organic wastes, C molasses and concentrates. By 1980, the daily ration for almost five hundred thousand pigs from 25 to 90 kg was 2.4 kg/day (dry matter) of a mixture of processed swill and molasses, and supplementary concentrates, (MINAG 1982). In this way, processed swill, C molasses and concentrates, of 20, 80 and 90% dry matter respectively, represented approximately 37,33 and 30% of total daily dry matter consumption (see Chapter 6).

Performance was generally poor and since the results of several observation trials had shown the superiority of B molasses, it was decided to immediately extend those results to a commercial feedlot of 17,000 head. There, an experimental group of 220 pigs during a 92-day trial, showed a net liveweight difference of 12 kg in support of the use of B as opposed to C molasses. It was also observed that in addition to the difference in liveweight, the pigs ate their ration faster and did not leave any residues in the through as when C molasses was fed. Interestingly, the diarrhea-like symptoms subsided, the feces were harder. This meant that less water was needed to maintain pen hygiene and animal cleanliness. It was also observed that culling due to lameness and other hoof problems gradually subsided; this was attributed to the need for less water for cleaning and the dryer floor pens (Pérez et al., 1982).

Performance data summarized in Table 3.13 indicate a certain advantage to the use of B molasses (89% of available sucrose extracted), even when compared to high-test molasses. This could be partially due to the fact that the former contains less free, poorly-digested fructose (Chapter 1).

^* note: experimental results; if applied commercially reduce overall performance by about 15%

One of the most difficult problems encountered in commercial pig production in the tropics relates to the presentation of estrus, particularly during the hot and humid summer months (Tomes and Nielsen, 1979). In Cuba, Arias and Perez (1985) studied during two summer months the reproductive performance of four groups of weekly weaned sows, a total of 90 sows per group, fed to service or up to a maximum of ten days post-weaning, one kg of a 22% protein supplement and two kg of either C or B molasses, or only concentrates. Immediately after service, and until farrowing, all the sows were fed protein supplement and C molasses, the feeding system used at that time for all open and gestating sows in that country. During lactation concentrates were fed. Both the farrowing rate and the weaning to service interval improved with the use of B molasses (Table 3.14).

Source Arias et al. (1985); ^* a total of 356 sows in 4 treatments fed once daily during July/Aug in Cuba;^**22% CP in DM

The effect of feeding a restricted protein supplement and C or B molasses during two consecutive reproductive cycles was subsequently studied in two groups of sows of similar weight by Lan et al. (1986). During an average 33-day lactation, both groups were fed concentrates. At the end of the second reproductive cycle, the group fed B molasses weighed an average of 152 kg compared to 133 kg of the C molasses-fed group. A similar difference was reflected in the piglets. At 21 days of age, the average weight difference in favor of the piglets whose mothers had been fed during gestation a protein supplement, and B rather than C molasses, was 0.5 kg. At weaning this difference was 0.7 kg, some 11% superior to the piglet weaning weight of 6.2 kg obtained from sows fed the C molasses system. In addition to growth performance, Pérez (1988) reported that when B molasses replaced C molasses in the reproductive herd (see Table 3.9) the farrowing rate, measured the same month the following year and with data from eight thousand sows, improved from 75 to 82 percent.

Finally, in a review of nine publications related to the reproductive performance of sows fed high levels of C molasses, Velazquez and Diaz (1989) pointed out, that the average net liveweight gain of sows fed high levels of C molasses during gestation was only 15.4 kg, compared to a net loss during lactation of 17.5 kg. All of these results were incorporated into Cuba's swine feeding program which at that time meant 100,000 sows and progeny, approximately one million animals. The revised guidelines of the new feeding program were:

• upon weaning, and until presentation of estrus and service, sows would remain on concentrates;

• after service, sows were to be fed a restricted protein supplement, but B rather than C molasses; and

• C molasses was replaced by B molasses in all growing/finishing diets using: processed swill or a protein supplement and molasses (Table 3.9).

C molasses

This section on molasses would not be complete without a discussion of the information contained in Table 3.15 which compares the performance and the behavior of pigs fed ad libitum maize, high-test or C molasses diets (Ly and Castro, 1984). The authors confirm an earlier observation of Preston et al. (1968) that for pigs maize is superior to high-test molasses, which in turn is superior to C molasses. They also suggested that in the case of liquid molasses diets, perhaps the classic approach to animal nutrition does not apply; that is, since molasses diets contain less energy per unit of dry matter, the pigs should have compensated by eating more, however, the reverse seems to be the case. The pigs on the C and high-test molasses diets consumed 86 and 89%, respectively, of the total dry matter intake of the maize diet.

Other observations related to this phenomenon, but during the first stage of growth from 50 to 60 kg, and using torula yeast instead of fishmeal as the only source of protein, have shown that in some cases voluntary feed intake increases during the first stage, but that eventually feed consumption decreases, leading to an overall “normal” pig performance (Figueroa et al., 1988; Maylin et al., 1989). It has also been noted that with sucrose or molasses-based diets the pattern of feed intake is modified due, perhaps, to the concomitant metabolic acidosis from fructose in the diet (see Chapter 1).

The pigs on the C molasses diet, upon receiving their ration and during the first hour, ate 13.8 times and drank water 13 times. The authors suggest that this unusual water drinking pattern, also reported by Marrero and Ly (1977), might have influenced voluntary intake. Called “osmotic shock” by Figueroa et al. (1983), this phenomena perhaps explains the low dry matter content of the feces, 16% as compared to more than 30% on either the maize or high-test diets, as well as the diarrhoea-like symptoms of pigs fed high levels of C molasses.

Measurements during first hour of an once-daily, 8 am, ad libitum feeding:

Digestive parameters:

Source: Ly and Castro (1984); ^* all diets contained 2.5% saccharomyces yeast, the molasses and maize dietscontained 1.5% and 2.5% micro/macro elements, respectively

Protein molasses

Protein molasses, a liquid feed for swine of 36% dry matter (Argudin and Chong, 1972; ICIDCA, 1988) is made by combining on a dry matter basis 70% of B molasses with 30% torula yeast cream (Candida utilis). The yeast cream, a fermentation product of C molasses, contains between 44 and 46% protein in dry matter. Because it contains an average of 17% dry matter and the B molasses 82%, a common procedure is to mix two parts by weight of yeast cream to one of B molasses.

Figueroa (1989) reported that under commercial conditions a group of approximately three thousand pigs of average initial weight of 28.6 kg gained 507 g/day during a 120 day fattening period. The herd-average daily dry matter feed consumption was 2.45 kg; the dry matter feed conversion was 4.90.

CANE SUGAR

Raw cane sugar

There are few published reports on the use of raw cane sugar for fattening pigs. Perhaps this is because the major cane producing countries also produce molasses, no doubt a cheaper alternative. Nevertheless, one early study from the southern United States, referred to “sugar cane left standing in the fields due to a lack of information on how it could be used” (Singletary et al., 1957). The authors substituted maize for 10, 20 and 30% of raw sugar in 16% crude protein, free-choice rations for growing/finishing pigs of an initial liveweight of 29 kilograms. The average daily gain (g), air-dry daily feed consumption (kg) and feed conversion for the maize control diet and the treatments containing 10, 20 or 30% raw sugar groups were: 764, 3.0, 3.93; 818, 3.2, 3.88; 841, 3.1, 3.71 and 791, 3.0 and 3.77, respectively.

A second study, also 35 years ago (Thrasher et al., 1958), interestingly supports the current recommendation to restrict the amount of high-quality protein supplement to approximately 200 g/day in sugar cane product-diets for growing/finishing pigs. The authors designed a trial consisting of a maize control and five experimental groups. The first four experimental groups were fed 20, 30, 40 and 50% raw cane sugar in free-choice mixed rations that also contained maize and a protein supplement (Table 3.16). The fifth experimental group was fed raw sugar, maize and the protein supplement, free-choice, but separately. This last group, which gained weight at about the same rate, 795 g/day, as the maize control, consumed 2.63 kg daily, air-dry (43% sugar, 40% maize and 17% protein supplement). This meant that the pigs in group five consumed an average of 10% crude protein compared to 15% in the mixed rations. The intake of only 236 g/day of protein, in dry matter, compared to an average of 329 g in the other four groups that received mixed rations, represented a net saving of 28% protein, daily.

Source: Thrasher et al. (1958); ^* 20% alfalfa meal, 20% meat/bone meal, 52% soya bean meal and 8% other.

In an attempt to improve the daily liveweight gain and feed conversion in growing/finishing pigs when more than 30% C molasses in dry matter was used, Macleod et al. (1968) substituted raw sugar for molasses. The average daily gain improved as sugar replaced C molasses. Feed conversion was best on the high-test molasses control diet and deteriorated as the proportion of raw sugar decreased (Table 3.17). It was reported that the pigs fed 20% sugar, i.e. those fed the highest level of C molasses, produced a more liquid feces compared to that of the other diets.

Buitrago et al. (1969) substituted maize for raw cane sugar and found that as the amount of sugar was increased in the diet of growing/finishing pigs both the average daily gain and feed conversion improved (Table 3.18). For piglets, to improve palatability, a common commercial practice is to include from 5 to 15% of raw sugar (Ly, 1983).

Source: Macleod et al. (1968); ^* all diets contained in DM up to 25% fishmeal, 2.5% yeast and 1.5% minerals andvitamins

Source: Buitrago et al. (1969); maize was the alternative energy source, soya bean meal was the source of protein

Refined cane sugar

As refined cane sugar was used as a substitute for ground maize in exactly the same proportions as shown in the preceding table, both the average daily gains and the feed conversion improved (Table 3.19). In fact, Maner et al. (1969) demonstrated that by feeding a ration that contained 60% refined sugar, it would take only 70 days to fatten a pig! Brooks (1972) also demonstrated the superiority of refined sugar over maize for fattening pigs. A diet, in which the energy source consisted of 50% refined sugar and 10% fat, produced liveweight gains of 740 g/day and a feed conversion of 2.30. Growth performance on the maize diet was 700 g/day and feed conversion was 3.00 which meant that the refined sugar ration represented a 23% improvement in feed conversion. The data of Maner et al. (1969) indicate that there are no nutritional advantages favoring starch as opposed to sucrose-based diets. In fact, sucrose is completely absorbed in the small intestine and there are no significant amounts of carbohydrates fermented in the caecum and colon (Chapter 1).

Source: Maner et al. (1969); ^* % air-dry

C sugar (low-grade or crystal seed-sugar)

C sugar, also known as low-grade or crystal seed-sugar, is produced in a raw sugar factory during the production of raw commercial B sugar and B molasses. It is a non-commercial type of sugar of which one-third is used for “seeding” (hence its name); the other two-third's is normally dissolved and sent back to the boiling house for reprocessing (see Fig. 3.2). It has been suggested that the removal of excess crystal seed-sugar for animal feeding would improve the overall thermal balance of a traditional sugar factory (Pérez, 1990). In this regard, Sarria (1990) reported an average daily gain of 643 g when C sugar was used as the only energy source for growing/finishing pigs. Table 3.5 refers to a dry ration for piglets, called “soya-sugar”, that contains in air-dry: 50% C sugar, 30% soya bean meal, 10% rice polishing and 10% of a macro/micro premix. It was emphasized that because soya bean meal was used, the protein level was reduced by 25 percent.

CANE REFINERY PRODUCTS

Syrup-off and refinery final molasses

Syrup-off, known also as “liquor-off” or “jett”, is the end-product obtained after centrifuging the final massecuite in a raw sugar refinery. It contains 90 to 92% sucrose and for that reason is normally sent back to the raw sugar, or front section of the refinery, where it is reprocessed in order to recover additional sucrose. However, similar to the process for upgrading crystal seed-sugar (C sugar), it is a costly, energy-consuming operation. In Cuba, diluted “syrup-off” has been used as an excellent substitute for fresh cane juice during mill maintenance or the 6-month, non-cane season. Interestingly, the refineries generally only shut down for one month each year. There is still another type of molasses produced in a raw sugar refinery. It is called “refinery final molasses”. However, because it represents less than 1% of the processed raw sugar, it is usually deposited in the C molasses tanks.

“Syrup-off” was compared to both C molasses and refinery final molasses in a 112 day feeding trial in which the three energy sources made up 65% of the dietary dry matter (Pérez et al., 1984). The protein supplement was dry torula yeast, 34%, with an added 1% mineral-vitamin premix. The pigs fed “syrup-off” grew 25% faster, as well as converted their ration, including the protein supplement, into liveweight 22% more efficiently compared to the group fed C molasses (Table 3.20). Figueroa (1990) also reported that pregnant sows, fed “syrup-off” or C molasses as a major source of energy during gestation, were heavier at 105 days of gestation (61.1 vs. 48.1 kg) and farrowed more live piglets (10 vs. 8.9).

Source: Pérez et al. (1984)

RESIDUES

Filter-press mud (filter-cake)

Filter-press mud of approximately 25 to 28% dry matter represents 3% of millable sugar cane. Because it ferments within 24 hours, it is normally returned to the cane fields as fertilizer. Filter-press mud has been used experimentally to replace 5 or 10% of dietary dry matter in C molasses basal diets for pigs (Olengui, 1978, cited by Castro and Lon-Wo, 1990) and up to 13% in processed swill feeding systems (Table 3.21); however, both studies showed that the addition of only 5% filter-mud adversely affected performance.

Source: Patterson et al. (1983)

Cane wax oil

Cane wax oil results from the purification of raw cane wax extracted from filter-press mud. One ton of millable cane produces 33 kg of filter-press mud which contains 0.8 kg of unrefined wax. The composition of the unrefined wax is: 40% refined wax, 40% oil and 20% resin. This means that one ton of millable cane contains 0.32 kg of cane wax oil (MINAZ, 1980). The use of this product to increase the energy content of C molasses diets for growing/finishing pigs (Brito et al., 1985), and for gestating sows (Díaz and Rodriguez, 1987) was unsuccessful. The authors attributed the extremely poor results to impurities in both the oil and the C molasses.

Bagasse pith

Bagasse pith, also known as “fines”, have been fed at air-dry levels of either 30 or 40% together with 30% C molasses, 27% of a protein supplement and 3% of macro/micro elements in a complete self-fed ration for pregnant sows housed in dry lot (Thrasher and Brown 1961). The 30% bagasse pith ration contained 12% of ground maize. The control group was fed a cereal-based gestation ration at a rate of 2.25 kg AD/day. The sows fed the ration containing 30% bagasse pith consumed 53% more compared to those on the 40% pith ration and therefore had the highest daily feed cost. The authors reported that the 40% high-fibre bagasse ration was very satisfactory for self-feeding under dry lot conditions and suggested it also be tried under pasture conditions.

Fresh sugar cane juice scums

The term sugar cane juice “scums” refers to the flocculated, colloidal-like material removed from the surface of boiling cane juice during the production of pan sugar. It is produced by adding calcium to the gently boiling juice while agitating the mixture with certain tree branches that contain tannins which coagulate the extraneous materials at the surface. Besides these residual tannins, the scums contain sugars, minerals, proteins and particles of soil that have adhered to the cane stalk (Preston and Murgueitio, 1992). They ferment rapidly, generally within 24 hours.

Scums, which contain only 20% dry matter, can replace cereal grains in the diet of finishing pigs but tend to cause diarrhoea in younger pigs and in lactating sows (Preston and Sansoucy, 1987). Sarria et al. (1990) reported an average growth performance of 670 g on nine small Colombian pan-sugar (panela) farms for growing/finishing pigs fed 500 g/day of a 40% protein supplement and free-choice fresh scums. There results were superior to those of the Philippines, where pigs fed 0.5 kg soya bean meal and fresh scums grew at only 430 g/day, however, double their previous performance (Table 3.7).

The production of pan sugar, a batch-type process, often requiring up to three days to complete, means that by the time the second batch is finished, the scums, which ferment within 24 hours, are no longer usable. A practical method of conservation is to boil the fresh scums in open vats to about 50–60% solids. In Latin America, this material is known as concentrated scums or as “melote”.

Concentrated scums (melote)

The performance of three groups of growing/finishing pigs, fed free-choice concentrated scums mixed with two parts of water and different amounts of protein supplement, supports the thesis that 200 g/day of high-quality protein during both the growing and finishing phases is optimal (Table 3.22). An additional trial in Colombia compared diluted, concentrated sugar cane scums to fresh cane juice. The supplement was 500 g/day of a 40% protein supplement based mainly on soya bean meal. Growth performance was superior (780 vs. 640 g); total dry matter intake was higher (2.8 vs. 2.4 kg) and feed conversions were better (3.70 vs. 3.80) on the concentrated scums feeding system (Sarria et al. 1990).

Source:Moreno et al. (1989), cited by Sarria et al. (1990); ^* 200 and 150 g/d of protein during growing and finishingphases, respectively; ^** 200 g/d during both phases; ^*** 300 g/d during both phases

SUGAR CANE STALKS

Fresh, clean (millable) cane stalks

Surprisingly, there is very little information on the use of fresh, clean cane stalks, chopped or ground, for pigs. In view of the performance of growing/finishing pigs fed 500 g/day high-quality protein supplement and free-choice cane juice, perhaps similar studies will determine this same requirement for ground sugar cane.

In Haiti, the work of Bien-Aime and Francois (1990) showed that pigs are only slightly less efficient than simple cane crushers in their ability to extract juice from chopped sugar cane: 43% compared to 49% in a crusher. These authors offered pigs either fresh juice or chopped cane; the protein sources were soya bean meal and fresh Leucaena leaves. The control treatment was a maize/soya bean meal ration (Table 3.23). They concluded that even if the chopped cane system took longer, five months and 25 days, it was better than the results obtained by many commercial farmers in Haiti, and definitely superior to the 12 and 24 months required by the poor peasant farmer to fatten a pig.

Source: Bien-Aime and Francois (1990);^* fresh Leucaena leaves

In Trinidad and Tobago, a FAO Technical Cooperation Project on Sugar Cane for Livestock has pursued this idea. The possibility to use the same machine to grind sugar cane for both pigs and small ruminants could be decisive for the resource-limited, small-scale farmer. It was reported that one farmer ground the stalk to a sawdust-like consistency, added 30% water (by weight), added cooked chicken entrails and fed his pigs this slurry. The squeezed-out fibre was subsequently collected and fed to his small ruminants (FAO, 1992b).

Sugar cane pith

In Barbados, fresh sugar cane pith has been used experimentally as the major source of energy in rations for growing/finishing pigs. In a project designed to use the rind of the cane stalk to manufacture compressed wallboard, the inner portion, 80% of the air-dry weight of the stalk, was used as a major source of energy for all kinds of livestock (James, 1973). For pigs, the fresh pith was incorporated in a 16% iso-proteic diet at air-dry levels of 35, 50 and 75 percent. Raw sugar and water were added (Table 3.24). Pigs of initial weight of 20 kg were assigned to three experimental groups and fed twice daily with ration allocations based on NRC recommendations at that time. A fourth group constituted a cereal control. Performance was best where either 35 or 50% of pith was used.

Source: James (1973); ^* all pith diets contained 20% of a 38% crude protein supplement

A second trial produced entirely different results. It examined the effect of using a level (air-dry) of 60% fresh cane pith in free-choice rations calculated for 15.5% crude protein in dry matter, and in which, either raw sugar or C molasses, or both, were added. Twenty-five percent of a 38% protein supplement was the only source of protein used in the pith diets. The cereal control ration was of commercial origin. The pigs on the cane pith rations gained significantly less (451 vs. 686 g/day) and converted their rations into liveweight 20% less efficiently; however, the authors, maintained that there was a decided advantage to using up to 75% local ingredients (Donefer et al.(1975).

Sugar cane meal

Sugar cane meal, clean cane stalks dried six to eight hours prior to grinding, has been incorporated at levels of 10, 20 and 30% in rations for weaned piglets (Table 3.25). The composition of the meal (dry matter) was: crude protein, 2.4%; ash, 4.6%, crude fibre, 26.0% and total sugars, 66.0 percent. It contained 90% dry matter and hemicellulose represented 45% of the plant cell wall.

At a level of 20% in the diet, there was no significant liveweight or feed conversion difference with respect to the cereal control. It was suggested that performance could be partially explained by the relatively high digestibility that pigs show for hemicellulose.

Source: Lamazares et al. (1988); ^* all diets contained 8% of fishmeal, 0.8% of calcium carbonate and 2% of avitamin/mineral premix; the control diet, in addition, contained 13.2% of rice polishing and 1% of dried grass meal

Protein-enriched sugar cane meal

Protein-enriched sugar cane meal (Saccharina) was first described by a group of Cuban researchers interested in promoting the use of sugar cane in concentrate rations for dairy cows (Elias et al., 1990). They proposed a process for the solid-state fermentation of carbohydrates in sugar cane: non-protein nitrogen, in the form of urea, mixed with ground cane, would supposedly promote the growth of microbes and yeasts that adhered naturally to the cane stalk. The multiplication of single cell organisms would increase the level of protein to approximate that of a cereal.

Source: Lezcano et al, (1990);^* 22% CP in DM; the ration also contained macro/micro elements

The first published trial (Table 3.27) using protein-enriched sugar cane meal for pigs referred to weaned piglets of an average liveweight of 7.2 kg allocated to five experimental rations in which protein-enriched sugar cane meal replaced from 10 to 50% of cereals (Lezcano et al., 1990). During a four-week feeding trial, the piglets were offered, weekly, 270, 470, 700 and 870 g/day of the experimental rations. Performance was superior when 10 or 20% of the enriched meal was incorporated in the diet. It was reported that when more than 20% of protein-enriched meal was used the piglets did not consume all of their ration.

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