4. Crops for silage production in semiarid regions

The mains characteristics that determine the fermentation profile during ensiling involve the interaction of factors such as: DM content, WSC concentration, and buffering capacity of plant. In the case of semiarid, plant species resistance to hydric deficit and climatic conditions are indicated to ensiling. The main forages are sorghum, pearl millet, tropical grasses, leguminous, and cactus pear.

#### 4.1. Sorghum

unavoidable, such as biochemist changes, plant respiration, and fermentation (Table 3), other

The energy and dry matter disappearance is an indicative of losses in the ensiling process. The residual respiration during filling the silo and immediately after sealing, types of fermentation, effluent production, undesirable fermentation during the storage, and aerobic deterioration

The losses related to respiration usually occur early. The respiration in silo initially occurs due to the presence of oxygen in the ensiled materials, thus the cellular respiration use the air oxygen and substrates producing CO2, heat, and H2O. Some factors can affect the respiration rate in the silo, such as temperature, which increase the initial rate of reaction and destruction of enzymes, usually by denaturation; oxygen concentration, the high amount of oxygen in the silo promotes an increase in the respiration rate and higher the temperature, and consume more energy; WSC content: the amount of soluble substrates in ensiled materials can influence

Silage fermentation usually causes DM losses due to the activity of microbial and enzymes. The losses related to the fermentation represent the highest percentage of losses in the silage process. These losses can be resulting from the production of water, gas, heat, and effluents

The effluent losses are associated with the DM content of plant, the activity of the water metabolism and the physical procedure of cutting and application of additives in ensiled forage [23] and DM losses can be highly variable [16]. After evaluating the sorghum silages in

In ensiling, besides DM losses, nutritional losses should also be taken into account. Sugarcane and sorghum silages can show high nutritional losses because of a high content of WSC, which may result in increase in alcoholic fermentation. Many studies indicate that the application of additives in the ensiled material considerably reduced these losses of substrates [24–26].

Other fermentation can also occur and reduce the nutritive value of silage, as proteolysis. The proteolysis is associated with DM, protein, WSC content, pH, and ensiling time [27]. It is an undesired reaction because the resulting products of the process (ammonia and amines, prin-

In discharge of silo to offer silage to animals aerobic deterioration can also occur, which is one of the main problems after exposure to air [28]. This process occurs due the penetration of air in ensiled materials, which is favorable for the grown of aerobic microorganisms, acid tolerant, and the oxide products resulting in silage fermentative process [29]. The air exposure of silage

The mains characteristics that determine the fermentation profile during ensiling involve the interaction of factors such as: DM content, WSC concentration, and buffering capacity of plant.

types of losses can be avoided with appropriate practice of the ensiling procedures.

are the main causes of energy and dry matter losses [21].

the respiration, since they are consumed during respiration.

Brazilian semiarid we observed a variation of 10–24% DM losses.

can chance its chemical compositions and alter the nutritional value.

4. Crops for silage production in semiarid regions

during the fermentation process [22].

72 Advances in Silage Production and Utilization

cipally) indicate high nutritional losses.

Sorghum (Sorghum bicolor L. Moench) is an appropriate grass for silage with agronomic and nutritional characteristics, because it is tolerant to drought and responds even in soils with limited nutrients [30] and its phenotypic characteristics facilitate planting, management, harvesting, and storage. The other significant characteristic of sorghum is that it will regrowth after each harvesting [31].

The sorghum is a resistant to hydric deficit in semiarid. Their resistance is associated with the physiology characteristics and efficiency of rain. Researchers evaluated the efficiency of rain in sorghum genotypes in semiarid and found positive results, values between 944.37 and 126.25 kg DM/ha/mm that indicated high efficiency in covert water of rain in production [32].

In addition to their agronomic traits, sorghum has desirable characteristics for fermentation, such as a suitable dry matter content, high carbohydrate concentration, and low of buffering substance content [33, 34].

Sorghum is a crop that has desirable characteristics for the production of silage; however, as the WSC concentration is higher in the stem, forage sorghum and saccharine sorghum usually have high concentration of carbohydrates, which can facilitate the multiplication of yeasts, molds, and enteric bacteria. The presence these microorganisms cause losses in silage process of sorghum.

In general, the fermentation losses imply in the reduction of the availability of the ensiled forage, since there is no way to recover the DM losses in the form of gases and effluent.

The exposure of silage to air, converting the anaerobic environment (responsible for the conservation of forage) to aerobic, can cause changes in its chemical composition, altering its nutritional value, because the population of microorganisms that were dormant (bacteria, yeasts, and then mold action) and with oxygen began intense metabolic activity [35].

There is reduction in soluble components of silage, which are used as substrates for these microorganisms [30] and may even be a degraded part of the fibrous portion of food by fungal microbiota [28].

Evaluation of the aerobic stability of sorghum silages [26] found the aerobic deterioration losses of 85.6 kg/t DM in silages upon exposure to air during 48 hours. As the air to silage exposure is unavoidable during discharge, many research studies aim to reduce the aerobic deterioration with the use of additives [36].

The adding urea to acidic silage can neutralize part of acidity in the chemical reaction by partial neutralization, where, in an acid environment, an agent that has alkalizing action forms salts of organic acids [37] and subsequently providing the nitrogen applied [24].

Chemical additives such as urea can also benefit from the silage sorghum (Table 4). Although sorghum silage with urea present pH values and higher N ammonia, it does not mean that the


predisposition to the development of deleterious microorganisms such as yeasts, and when

Ensiling of Forage Crops in Semiarid Regions http://dx.doi.org/10.5772/101990 75

In turn, grasses silages have lower amounts of WSC, buffering capacity, and relatively larger pH, which would lead to an increase in the production of acetic acid, the resulting product is essentially heterofermentative bacteria. Acetic acid has antifungal properties and may delay the development of fungi and degradation of nutrients in silage with high nutritional value,

Considering these characteristics, the production of mixed silage sorghum with grass could promote appropriate fermentation profile, resulting in silage quality, as well as increase the aerobic stability of silage when exposed to air in the discharge phase, resulting in the reduction

Evaluating sorghum silage mixed with 0, 25, 50, 75, and 100% of elephant grass, researchers found losses are reduced by gases (up to the level of 50%) and effluent (when added 75% grass elephant) in sorghum silage mixed with elephant grass [40]. Still mixed with elephant grass silages showed high resistance to heating after exposure to air of silage, there was an improve-

The pearl millet (Pennisetum glaucum) is a grass of tropical region that can be considered alternative to forage production in Brazilian semiarid because it is a short cycled plant with high nutritive value adapted to climatic and soil conditions and it has great potential of production [41]. Because of its hardiness, rapid growth, adaptation to low soil fertility, and excellent biomass production capacity, it is an alternative to semiarid climates, where there are

This grass species has been widely used by producers as an alternative to attempt the requirements of animals in the critical part of the year. Pearl millet has been used as forage for the production of silage in periods of drought because of its specific characteristic such as more persistent drought, adapted to low fertility soils, fast growth, and good biomass production

Researchers evaluated the recovery of dry matter and losses of dry matter in the form of gases and effluent, and pH in silage of two pearl millet genotypes under nitrogen fertilization and found that the silages with lower pH were decreased the DM recovery and increased the

The release of effluent can contribute to significant losses in the silage, considering that the DM content of pearl millet plants is relatively low. In many cases, good results have been achieved

The incorporation of substances that absorb moisture inside the silo, such as citrus pulp, corn disintegrated with straw, corn cornmeal, and sorghum, favors the fermentation process. The incorporation of 3–7% of additives is sufficient to increase the DM content of the silage up to 25% DM, but this strategy should always be evaluated based on cost. Another alternative is to

soluble carbohydrates, which triggered the alcoholic fermentation [16].

under aerobic conditions in the silo-opening phase, aerobic stability is reduced.

thus increasing the aerobic stability.

ment in the aerobic stability of silage.

of aerobic degradation losses.

4.2. Pearl millet

[35, 42].

large climatic uncertainties.

by using moisture-absorbing additives.

Note: LB = Lactobacillus buchneri; LP = Lactobacillus plantarum; ND = Not detected. Sources: Adapted from Filya [38] and Santos [26].

Table 4. Values of pH, relation ammoniacal nitrogen/total nitrogen (NH3/TN), lactic acid (LA), acetic acid (AA), and ethanol (ET) of sorghum silage.

fermentation process is undesirable. Urea may act primarily in the metabolism of microorganisms, such as yeasts, reducing the conversion of the soluble compounds to ethanol, reducing DM losses. Furthermore, the addition of urea in sorghum silage had no negative effect on the production of lactic acid [26].

The sorghum has high WSC that can excessively acidify the silage due to excessive lactic acid production. The effect of different doses of urea on sorghum silage [26] found that the addition of urea reduced DM and WSC losses, reducing the production of ethanol from treated silages. Another benefit noted by the author was a high possibility of recovery of the nitrogen applied in the silages by incorporating the biomass ensiled.

The use of microbiological and chemical additives in sorghum silage can benefit from the fermentation process, and prolong the aerobic stability of silages [26].

After evaluating sorghum silage inoculated with lactic acid bacteria homofermentative and heterofermentative (Table 4), the researchers observed that the pH and WSC concentration decreased during fermentation, while increased lactic acid, acetic acid, ethanol, and ammonia content [38].

The addition of inoculants from lactic acid bacteria, such as Lactobacillus buchneri and Lactobacillus plantarum can benefit fermentation. Sorghum silages additive with L. plantarum showed low pH, lower content of acetic acid, ammonia nitrogen, and increased the production of lactic acid [38]. While silage inoculated with L. buchneri had a higher content of acetic acid and ethanol and lower lactic acid concentration [38].

L. buchneri is heterofermentative bacteria capable of converting water-soluble carbohydrates into lactic acid and other compounds with less acidifying power of the medium, such as acetic acid [39]. Still, these bacteria are capable of producing ethanol, which justifies higher values in the silage [39].

Another alternative is production of sorghum silage mixed with grasses. The sorghum silage has a high carbohydrate concentration, which implies the production of acid silage with predisposition to the development of deleterious microorganisms such as yeasts, and when under aerobic conditions in the silo-opening phase, aerobic stability is reduced.

In turn, grasses silages have lower amounts of WSC, buffering capacity, and relatively larger pH, which would lead to an increase in the production of acetic acid, the resulting product is essentially heterofermentative bacteria. Acetic acid has antifungal properties and may delay the development of fungi and degradation of nutrients in silage with high nutritional value, thus increasing the aerobic stability.

Considering these characteristics, the production of mixed silage sorghum with grass could promote appropriate fermentation profile, resulting in silage quality, as well as increase the aerobic stability of silage when exposed to air in the discharge phase, resulting in the reduction of aerobic degradation losses.

Evaluating sorghum silage mixed with 0, 25, 50, 75, and 100% of elephant grass, researchers found losses are reduced by gases (up to the level of 50%) and effluent (when added 75% grass elephant) in sorghum silage mixed with elephant grass [40]. Still mixed with elephant grass silages showed high resistance to heating after exposure to air of silage, there was an improvement in the aerobic stability of silage.

#### 4.2. Pearl millet

fermentation process is undesirable. Urea may act primarily in the metabolism of microorganisms, such as yeasts, reducing the conversion of the soluble compounds to ethanol, reducing DM losses. Furthermore, the addition of urea in sorghum silage had no negative effect on the

Table 4. Values of pH, relation ammoniacal nitrogen/total nitrogen (NH3/TN), lactic acid (LA), acetic acid (AA), and

TRAT pH NH3/TN LA AA ET Sorghum 4.73 0.228 6.01 0.83 0.44 Sorghum + LB 4.78 0.257 3.09 3.93 0.46 Sorghum + LP 4.25 0.189 12.46 0.56 0.40 Sorghum + 0.5% urea 3.69 0.169 5.27 0.85 0.60 Sorghum + 1.0% urea 3.73 0.401 6.69 0.37 0.26 Sorghum + 2.0% urea 3.76 0.525 5.71 0.70 ND Sorghum + 4.0% urea 3.98 0.767 6.72 0.83 ND

The sorghum has high WSC that can excessively acidify the silage due to excessive lactic acid production. The effect of different doses of urea on sorghum silage [26] found that the addition of urea reduced DM and WSC losses, reducing the production of ethanol from treated silages. Another benefit noted by the author was a high possibility of recovery of the nitrogen applied

The use of microbiological and chemical additives in sorghum silage can benefit from the

After evaluating sorghum silage inoculated with lactic acid bacteria homofermentative and heterofermentative (Table 4), the researchers observed that the pH and WSC concentration decreased during fermentation, while increased lactic acid, acetic acid, ethanol, and ammonia

The addition of inoculants from lactic acid bacteria, such as Lactobacillus buchneri and Lactobacillus plantarum can benefit fermentation. Sorghum silages additive with L. plantarum showed low pH, lower content of acetic acid, ammonia nitrogen, and increased the production of lactic acid [38]. While silage inoculated with L. buchneri had a higher content of acetic acid and

L. buchneri is heterofermentative bacteria capable of converting water-soluble carbohydrates into lactic acid and other compounds with less acidifying power of the medium, such as acetic acid [39]. Still, these bacteria are capable of producing ethanol, which justifies higher values in

Another alternative is production of sorghum silage mixed with grasses. The sorghum silage has a high carbohydrate concentration, which implies the production of acid silage with

production of lactic acid [26].

ethanol (ET) of sorghum silage.

Sources: Adapted from Filya [38] and Santos [26].

74 Advances in Silage Production and Utilization

content [38].

the silage [39].

in the silages by incorporating the biomass ensiled.

ethanol and lower lactic acid concentration [38].

fermentation process, and prolong the aerobic stability of silages [26].

Note: LB = Lactobacillus buchneri; LP = Lactobacillus plantarum; ND = Not detected.

The pearl millet (Pennisetum glaucum) is a grass of tropical region that can be considered alternative to forage production in Brazilian semiarid because it is a short cycled plant with high nutritive value adapted to climatic and soil conditions and it has great potential of production [41]. Because of its hardiness, rapid growth, adaptation to low soil fertility, and excellent biomass production capacity, it is an alternative to semiarid climates, where there are large climatic uncertainties.

This grass species has been widely used by producers as an alternative to attempt the requirements of animals in the critical part of the year. Pearl millet has been used as forage for the production of silage in periods of drought because of its specific characteristic such as more persistent drought, adapted to low fertility soils, fast growth, and good biomass production [35, 42].

Researchers evaluated the recovery of dry matter and losses of dry matter in the form of gases and effluent, and pH in silage of two pearl millet genotypes under nitrogen fertilization and found that the silages with lower pH were decreased the DM recovery and increased the soluble carbohydrates, which triggered the alcoholic fermentation [16].

The release of effluent can contribute to significant losses in the silage, considering that the DM content of pearl millet plants is relatively low. In many cases, good results have been achieved by using moisture-absorbing additives.

The incorporation of substances that absorb moisture inside the silo, such as citrus pulp, corn disintegrated with straw, corn cornmeal, and sorghum, favors the fermentation process. The incorporation of 3–7% of additives is sufficient to increase the DM content of the silage up to 25% DM, but this strategy should always be evaluated based on cost. Another alternative is to prewilting of the forage to be ensiled. This practice is effective. However, due to the significant increase in hand-to-work has proved more viable for small-scale silage production.

WSC content, resulting in reduction of pH and ammonia-N concentration and increasing the

Ensiling of Forage Crops in Semiarid Regions http://dx.doi.org/10.5772/101990 77

Other sources that are used as additives, which are rich in soluble carbohydrates, are the residuals of fruit processing, such as cherry, pineapple, guava, passion fruit, mango, and papaya. These residues are usually dry, and used as both WSC sources and to increase the

The leguminous species found in semiarid regions are drought tolerance. In order to reduce production costs, leguminous are often used as protein banks to feed ruminant animals, since

The main leguminous fed to cattle in the semiarid region are leucaena (Leucaena leucocephala), pigeon pea (Cajanus cajan), Gliricidia (Gliricidia sepium), jitirana (Merremia aegyptia), sisal (Agave

Although these species are widely used as protein bank, some species of leguminous produced in the semiarid region have antinutritional compounds such as cyanide and tannin. These compounds may have a negative effect on ruminal degradation and become toxic when leguminous are present in excess. The ensiling process can soften or remove these undesirable compounds, improving the quality of food that provides to animals. This process has often

Leguminous species are not favorable for silage because of low concentrations of dry matter and water-soluble carbohydrates, and high protein content and buffering substances [51]. Because the amount of soluble carbohydrates, DM content, and buffer capacity [39], the fermentation process of leguminous silage may not be acceptable. However, the use of addi-

The fermentation of the silage leguminous is resistant to pH reduction due to the high buffering capacity and low content of soluble carbohydrates, which makes the highest production of lactic acid. There are a high number of pulses present in semiarid. Thus, it is important to use techniques which aimed at improving the ensiling process of legumes, making it favorable for silage. The dry matter content directly influences the fermentative activity [13]. High moisture content and buffering capacity associated with low soluble carbohydrate content can lead to

Leguminous have a high content of protein and minerals. Salts of organic acids, sulfate, nitrates, chlorides, and orthophosphate form the anion fraction of forage, which correspond approximately 68–80% of buffer capacity [52]. The disadvantages of leguminous silage are the need for increased lactic acid production to compensate for the high buffering capacity and

Some strategies are used which can modify and improve the fermentation process of leguminous ensiling. In Table 5, we found that the silage pH perennial peanut had reduced after the

DM content [48].

4.4. Leguminous

DM content of grass silage.

the protein is expensive nutrient for animal nutrition [49].

sisalana), perennial peanut (Arachis pintoi), among others.

tives can improve the silage fermentation of these leguminous.

increased butyric fermentation, with losses of nutrients in the final food.

been used for feeding animals in feedlot [50].

reduce the pH to values below 4.0 [53].

#### 4.3. Grasses

Grasses cultivated under tropical conditions have high production in favorable season and reduction in unfavorable periods. Usually, there has been a fodder surplus in times of water, which should be maintained for subsequent supply in the drought period of the year. In this context, the grasses surplus ensiling can be a good practice to increase the supply of dry matter to animals in unfavorable times. Nevertheless, grasses have low DM and WSC content, as well as a limited number of indigenous bacteria, so that they require the techniques that increase their DM content and favoring the production of lactic acid bacteria [43].

The tropical grasses have low dry matter content, high power buffer, and low in soluble carbohydrates in the growth stages that have adequate nutritional value, which may harm the conservation process through the silage due to the possibilities of arising secondary fermentations, increasing the losses, and reducing the final quality of the ensiled material [44].

Researchers evaluated the effect of plant maturity on the DM content [45] and found the DM contents of 19.42, 21.06, 20.25, and 22.41% for 30 crops with heights of 40, 50, and 60 cm, which are unfavorable for appropriate fermentation of grass silage.

The WSC content in grasses is generally low depending on species and time of harvesting. The minimum WSC concentration to ensure the appropriate fermentation process is in the range 8–10% (DM basis) [13]. The WSC represents the main substrate for lactic acid bacteria, and must be at high concentration in plants prior to ensiling, so that the fermentation process is accelerate and the pH lowered rapidly, thereby inhibiting the growth of undesirable microorganisms.

The WSC and DM contents and buffering capacity influence directly the fermentation process of silage. Researchers [46] found that the DM and WSC content increases with the increase of regrowth age. Water-soluble carbohydrate levels in tropical grasses are low and thus it is difficult to reduce pH because of the absence of substrate for lactic acid bacteria, which suppresses the fermentation process.

Besides WSC and DM contents, buffering capacity also influences the ensiling process. The buffering capacity of forage resists changes in pH, which reduced the rapid lowering of pH necessary for forage preservation. The ratio of WSC and buffering capacity is important for the silage process. When the ratio is decreased it needs to increase in the DM content to avoid undesirable fermentation inside the silo.

The control of the ensiling process may be realized by the use of additives. Researchers [47] evaluated the effect of citrus pulp on Tanzania grass silage and found increased ratio of WSC and buffering capacity, which resulted in improved fermentation characteristics of silages with reduction of pH and ammonia-N values.

Another way to increase the level of soluble carbohydrates of forages before ensiling is the inclusion of sugarcane. The benefits of using sugarcane are similar to molasses to increase the WSC content, resulting in reduction of pH and ammonia-N concentration and increasing the DM content [48].

Other sources that are used as additives, which are rich in soluble carbohydrates, are the residuals of fruit processing, such as cherry, pineapple, guava, passion fruit, mango, and papaya. These residues are usually dry, and used as both WSC sources and to increase the DM content of grass silage.

### 4.4. Leguminous

prewilting of the forage to be ensiled. This practice is effective. However, due to the significant

Grasses cultivated under tropical conditions have high production in favorable season and reduction in unfavorable periods. Usually, there has been a fodder surplus in times of water, which should be maintained for subsequent supply in the drought period of the year. In this context, the grasses surplus ensiling can be a good practice to increase the supply of dry matter to animals in unfavorable times. Nevertheless, grasses have low DM and WSC content, as well as a limited number of indigenous bacteria, so that they require the techniques that increase

The tropical grasses have low dry matter content, high power buffer, and low in soluble carbohydrates in the growth stages that have adequate nutritional value, which may harm the conservation process through the silage due to the possibilities of arising secondary fermentations, increasing the losses, and reducing the final quality of the ensiled material [44].

Researchers evaluated the effect of plant maturity on the DM content [45] and found the DM contents of 19.42, 21.06, 20.25, and 22.41% for 30 crops with heights of 40, 50, and 60 cm, which

The WSC content in grasses is generally low depending on species and time of harvesting. The minimum WSC concentration to ensure the appropriate fermentation process is in the range 8–10% (DM basis) [13]. The WSC represents the main substrate for lactic acid bacteria, and must be at high concentration in plants prior to ensiling, so that the fermentation process is accelerate and the pH lowered rapidly, thereby inhibiting the growth of undesirable micro-

The WSC and DM contents and buffering capacity influence directly the fermentation process of silage. Researchers [46] found that the DM and WSC content increases with the increase of regrowth age. Water-soluble carbohydrate levels in tropical grasses are low and thus it is difficult to reduce pH because of the absence of substrate for lactic acid bacteria, which

Besides WSC and DM contents, buffering capacity also influences the ensiling process. The buffering capacity of forage resists changes in pH, which reduced the rapid lowering of pH necessary for forage preservation. The ratio of WSC and buffering capacity is important for the silage process. When the ratio is decreased it needs to increase in the DM content to avoid

The control of the ensiling process may be realized by the use of additives. Researchers [47] evaluated the effect of citrus pulp on Tanzania grass silage and found increased ratio of WSC and buffering capacity, which resulted in improved fermentation characteristics of silages with

Another way to increase the level of soluble carbohydrates of forages before ensiling is the inclusion of sugarcane. The benefits of using sugarcane are similar to molasses to increase the

increase in hand-to-work has proved more viable for small-scale silage production.

their DM content and favoring the production of lactic acid bacteria [43].

are unfavorable for appropriate fermentation of grass silage.

4.3. Grasses

76 Advances in Silage Production and Utilization

organisms.

suppresses the fermentation process.

undesirable fermentation inside the silo.

reduction of pH and ammonia-N values.

The leguminous species found in semiarid regions are drought tolerance. In order to reduce production costs, leguminous are often used as protein banks to feed ruminant animals, since the protein is expensive nutrient for animal nutrition [49].

The main leguminous fed to cattle in the semiarid region are leucaena (Leucaena leucocephala), pigeon pea (Cajanus cajan), Gliricidia (Gliricidia sepium), jitirana (Merremia aegyptia), sisal (Agave sisalana), perennial peanut (Arachis pintoi), among others.

Although these species are widely used as protein bank, some species of leguminous produced in the semiarid region have antinutritional compounds such as cyanide and tannin. These compounds may have a negative effect on ruminal degradation and become toxic when leguminous are present in excess. The ensiling process can soften or remove these undesirable compounds, improving the quality of food that provides to animals. This process has often been used for feeding animals in feedlot [50].

Leguminous species are not favorable for silage because of low concentrations of dry matter and water-soluble carbohydrates, and high protein content and buffering substances [51]. Because the amount of soluble carbohydrates, DM content, and buffer capacity [39], the fermentation process of leguminous silage may not be acceptable. However, the use of additives can improve the silage fermentation of these leguminous.

The fermentation of the silage leguminous is resistant to pH reduction due to the high buffering capacity and low content of soluble carbohydrates, which makes the highest production of lactic acid. There are a high number of pulses present in semiarid. Thus, it is important to use techniques which aimed at improving the ensiling process of legumes, making it favorable for silage.

The dry matter content directly influences the fermentative activity [13]. High moisture content and buffering capacity associated with low soluble carbohydrate content can lead to increased butyric fermentation, with losses of nutrients in the final food.

Leguminous have a high content of protein and minerals. Salts of organic acids, sulfate, nitrates, chlorides, and orthophosphate form the anion fraction of forage, which correspond approximately 68–80% of buffer capacity [52]. The disadvantages of leguminous silage are the need for increased lactic acid production to compensate for the high buffering capacity and reduce the pH to values below 4.0 [53].

Some strategies are used which can modify and improve the fermentation process of leguminous ensiling. In Table 5, we found that the silage pH perennial peanut had reduced after the


Cactus pear has a low DM content and high WSC content, which could lead to alcoholic fermentation. However, researchers [56] evaluated cactus pear silages added with urea and found appropriate fermentation and low nutrient losses in silage. Despite some unfavorable attributes for silage, other characteristic of the cactus pear as per their bioactive compounds

Ensiling of Forage Crops in Semiarid Regions http://dx.doi.org/10.5772/101990 79

During rainy seasons, the cactus pear crop is not recommend for the ensiling process, because

Other aspects related to fermentation kinetics of cactus pear silage are the percentage of organic acids found in the cactus pear cladodes, such as oxalic, citric, malonic succinic, and

Cactus pear is forage with low DM content and high WSC concentration, which may favor the development of undesirable fermentation. However, the bioactive compounds present in cac-

The emulsifier gel is formed after cutting of cactus pear, resulting of breaking of chlorenchyma and parenchyma cells, it is store mucilage, a hydrocolloid that promotes fluid retention. The hydrocolloids are compounds formed by highly hydrophilic polysaccharides, which reduce the movement of water providing increased viscosity of materials and thus the mucilage formation [58]. These compounds may be responsible for reducing effluent losses due to

The interaction of forage characteristics and its associative effects, as well as the handling, during ensiling directly influence the efficiency of the preservation process. The additives, in general, have been test more often in order to facilitate the practice of forage silage with high moisture and WSC content. The reports evaluating the silage cactus pear are still incomplete,

In recent studies with silage palm, researchers [56] conducted experiments to evaluate the losses resulting from the fermentation of forage cactus pear using additives such as urea and wheat bran. It observed that the urea reduced the effect of the increasing DM content and the

The cactus pear has favorable characteristics for the ensiling process; it is possible to produce good quality silage. Although many believe that the characteristics of the cactus pear, especially high WSC content, imply in inadequate fermentation characteristics. Cactus pear consists of elements that make it potential to be used as silage. Still, cactus pear silage is composed of a diet rich in energy for ruminants, as well as serve as an alternative source of metabolic

The use of plant to appropriate silage in combination with cultivate, harvesting, and silo filling

water readily available in animal feed, especially in times of drought.

results in a successful preservation of forage as silage.

of the high moisture content that may bring difficulties in handling this material.

tartaric acids [57], which buffers the environment that impedes the lowering of pH.

tus pear promote homeostatic conditions in ensiled mass.

mucilage aggregates of fluid compounds.

as well as studies indicating additives for silage.

crude protein values of cactus pear silage.

5. Final considerations

must be taken into consideration.

Note: Means followed by the same letter in the column do not differ by 5% Tukey test. Source: Adapted from Paulino et al. (2009).

Table 5. Values of pH, relation ammoniacal nitrogen/total nitrogen (NH3/TN), lactic acid (LA), acetic acid (AA), butiric acid (BA), and propionic acid (PA) of perennial peanut silage.

addition of corn meal. Furthermore, additive increased the amount of lactic acid and acetic acid and reduced the content of ammonia nitrogen, butyric acid, and propionic acid. The additive corn meal positively changed the fermentation process of silage perennial peanut.

Other techniques such as wilting reduce losses in silage legumes. The wilting reduces the formation of organic ions that can result in the buffering effect on the silage fermentation process [54]. In Table 5, we confirmed the effect of wilting on silage perennial peanuts. Wilting reduced the pH, ammonia nitrogen content, butyric acid, and propionic acid, and increased the amounts of lactic and acetic acid. These changes are desirable, since lactic acid has preservative effect on the fermentation of silage to acidify [13].

The biological additives can be used in leguminous silage. Table 5 shows the results of the addition of inoculant in perennial peanuts silage, when the wilting before ensiling occurred. This can be explained by the fact that due to the lower moisture content in the forage activity of lactic acid bacteria is increases and reduced the activity of other bacteria, such as clostridia, which are sensitive to osmotic pressure.

#### 4.5. Cactus pear

The cactus pear (Opuntia ficus-indica and Nopalea cochenillifera Salm Dyck) has been increasing in the face of constant climate changes in the current production scenario [55] and its use in the objective Brazilian semiarid minimize the action of seasonality in the production process, providing energy and increasing the availability of water via food for animals.

In order to rationalize the use of this forage resource, the cactus pear as a silage is an alternative to this region. From the productive point, and the conservation of the nutritional value of the forage, the cactus pear silage maximizes the use of natural resources found in the Brazilian semiarid, enabling ranchers a new alternative for conservation of foods rich in water and energy, which adds more value to this Cactaceae in arid and semiarid regions.

Cactus pear has a low DM content and high WSC content, which could lead to alcoholic fermentation. However, researchers [56] evaluated cactus pear silages added with urea and found appropriate fermentation and low nutrient losses in silage. Despite some unfavorable attributes for silage, other characteristic of the cactus pear as per their bioactive compounds must be taken into consideration.

During rainy seasons, the cactus pear crop is not recommend for the ensiling process, because of the high moisture content that may bring difficulties in handling this material.

Other aspects related to fermentation kinetics of cactus pear silage are the percentage of organic acids found in the cactus pear cladodes, such as oxalic, citric, malonic succinic, and tartaric acids [57], which buffers the environment that impedes the lowering of pH.

Cactus pear is forage with low DM content and high WSC concentration, which may favor the development of undesirable fermentation. However, the bioactive compounds present in cactus pear promote homeostatic conditions in ensiled mass.

The emulsifier gel is formed after cutting of cactus pear, resulting of breaking of chlorenchyma and parenchyma cells, it is store mucilage, a hydrocolloid that promotes fluid retention. The hydrocolloids are compounds formed by highly hydrophilic polysaccharides, which reduce the movement of water providing increased viscosity of materials and thus the mucilage formation [58]. These compounds may be responsible for reducing effluent losses due to mucilage aggregates of fluid compounds.

The interaction of forage characteristics and its associative effects, as well as the handling, during ensiling directly influence the efficiency of the preservation process. The additives, in general, have been test more often in order to facilitate the practice of forage silage with high moisture and WSC content. The reports evaluating the silage cactus pear are still incomplete, as well as studies indicating additives for silage.

In recent studies with silage palm, researchers [56] conducted experiments to evaluate the losses resulting from the fermentation of forage cactus pear using additives such as urea and wheat bran. It observed that the urea reduced the effect of the increasing DM content and the crude protein values of cactus pear silage.

The cactus pear has favorable characteristics for the ensiling process; it is possible to produce good quality silage. Although many believe that the characteristics of the cactus pear, especially high WSC content, imply in inadequate fermentation characteristics. Cactus pear consists of elements that make it potential to be used as silage. Still, cactus pear silage is composed of a diet rich in energy for ruminants, as well as serve as an alternative source of metabolic water readily available in animal feed, especially in times of drought.
