**3. Nutritive value of silages**

in high amounts during a short period of time, the harvest season. Their preservation is required so they can be maintained for longer periods of time and used then as feed for animals. Silage represents an appropriate technique for this purpose. Also these materials may have adequate characteristics for ensiling, i.e., adequate moisture content and high fermentable carbohydrates. These byproducts may have low crude protein (CP) and mineral concentration and some

The improvement in nutritional quality of silages with nonconventional products may contribute to better animal feeding and production in tropical and subtropical areas. In addition, the use of alternative silages for animal feeding also may contribute by reducing environmental pollution. If by-products are not used in a short time (during the harvest season) they will be wasted in fields and in other cases they are burned. The objective of this chapter is to review the potential use of nonconventional silages (sugarcane tops [SCT], citrus byprod-

Silage is the preservation of feeds by anaerobic fermentation, usually by epiphytic bacteria that convert soluble carbohydrates mainly to lactic acid, and minor amounts of other volatile fatty acids. This reduces pH, which inactivates or inhibits microbial growth and results in the preservation of ensiled material. The ensiling process has four stages. In phase 1, aerobic microorganisms are active during the aerobic phase and occur under aerobic conditions during the few hours after ensiling. The ensiled material and facultative microorganisms (yeasts and enterobacteria) continue respiration, reducing the oxygen present. The enzymes of the ensiled material are active and pH is close to 6. In phase 2, anaerobic fermentation starts and continues for several days depending on substrate availability and ensiling conditions. Lactic bacteria become the main strain, and lactic acid reduces pH to 3.8–5.0. In phase 3, the process is stable, because changes can occur even in anaerobic conditions; most microorganisms reduce their numbers. During this phase, while the silage maintains anaerobic conditions, the process is practically unchanged. Phase 4 starts with the opening of the silage, or air exposure. The spoilage of silage in this phase is due to two processes: one is the degradation of acids that

ucts, pumpkin and cassava) for ruminant feeding in tropical and subtropical areas.

preserve the silage and the second is the spoilage by some microorganisms [1].

To produce good quality silage the following principles of fermentation during the phases of ensiling should be considered. For phase 1, adequate particle size of ensiled material with efficient filling (adequate packing density) will reduce aerobic respiration that allows faster growth of anaerobic microorganisms that produce lactic acid. Phases 2 and 3 can be enhanced and/or stabilized using some additives to silage during its preparation. For fast time of pH reduction and decrease dry matter (DM) losses, additives containing water soluble carbohydrates are used. To improve the fermentation process, some microbial inoculants, organic acids and enzymes can also be used. It is pointed out [2] that additives in silage stimulate lactic acid bacteria growth, responsible of silage stability, decreasing nutrient loss during fermentation and resulting in silage of higher nutrient concentration. Additives that contribute to silage

additives may help increase the nutritive value of these silages.

**2. Ensiling process**

86 Advances in Silage Production and Utilization

#### **3.1. Nutritive value of sugarcane tops silage**

In tropical areas, high amounts of vegetal biomass are produced due to the dynamic ecosystem, which is favored by the climatic conditions, i.e., humidity and temperature that propitiate accelerated growth of plants. An example of these plants is sugarcane (*Saccharum officinarum*); it can be fed to animals as an entire plant [3]. During the harvest of sugarcane for sugar extraction in the field an abundant biomass of sugarcane tops is wasted or burned; they constitute about 15% dry matter of total plant [4] and have greater protein content than the stalks [5], representing an alternative forage for ruminants in subtropical areas, where the climatic conditions complicate forage preservation; for this, sugarcane tops silage represents an alternative. The replacement of stalks by fresh tops of sugarcane in feedlot cattle diets has increased dry matter intake and body weight gain, **Table 1** [6]. The supplementation with urea of slow ruminal degradation to fresh sugarcane tops improved weight gain in lambs, **Table 2** [7]. Ruminal fermentation of fresh sugarcane tops is improved when supplemented with nitrogen and nonstructural carbohydrates [8], also similar results are observed in **Table 3** [9].


ADG = average daily gain; DMI = dry matter intake; feed conversion = feed intake/weight gain. Adapted with permission from Ferreiro and Preston [6].

**Table 1.** Summary of growth performance of feedlot cattle fed with different proportions of tops:stalks of sugarcane.


SCT = sugarcane tops; ADG = average daily gain; DMI = dry matter intake. Adapted with permission from Galina et al. [7].

**Table 2.** Summary of growth performance of feedlot lambs fed with sugarcane tops supplemented with slow degrading urea and corn plant.


of moisture are needed in silage [13]. From 30 to 45% BL enhanced lactic acid production and pH was acceptable; however, 60% of BL in silage resulted in high buffer capacity with high

Potential Use of Nonconventional Silages in Ruminant Feeding for Tropical and Subtropical Areas

http://dx.doi.org/10.5772/64382

89

In a study, sorghum stover was substituted with sugarcane top silage supplemented with urea [0 (T1), 5 (T2) and 10% (T3) DM] in high concentrate diets for feedlot hair lambs. It was observed a reduction of effective ruminal degradability with increased SCT contents in silage. Feedlot hair lambs observed reduced feed intake augmenting sugarcane tops silage in their ration. Nevertheless daily weight gain was not affected by diet. Feed efficiency (gain/feed intake) was not influenced by treatment. It was concluded that ensiled sugarcane tops constitute alternative

Most citrus species are well adapted in tropical and subtropical areas. Citrus fruits are used as dessert, although considerable amounts are used for industrial juice extraction. Citrus production in the producing countries is increasing [15]. The augmented disposal costs in many parts of the world have stimulated attention in utilizing citrus by-product feedstuffs (BPFs) as alternate feeds for ruminants [16]. In ruminant feeding, the principal citrus byproducts are fresh pulp, silage, dried, meal, molasses and citrus peel liquor. Other minor BPFs from citrus include cull or excess fruit. Citrus BPFs can be used as a high-energy feed in ruminant rations to support growth and lactation, with fewer negative effects on rumen

The world citrus production of the genus *Citrus* are sweet orange (*C. sinensis*: 67.8%), tangerine

The remaining 3.0% of the *Citrus* genera are sour orange (*C. quarantium*), shaddock (*C. grandis*), citron (*C. medica*) and lime (*C. aurantifolia*). The largest world orange juice producing countries are Brazil, the United States, Mexico, Spain, China and Italy. Other significant orange producing countries include South Africa, Israel, Egypt, Iran, Cuba, Costa Rica, Belize, Japan and Australia [17]. It would be convenient to develop methods to preserve the fruit surplus during the production season in tropical countries that would enable this plant material to be

It was showed that ensiling citrus by-products are possible; however, the high water content might affect the quality of the product [16]. This sense, citrus pulp silage produces high quality fermentation when straw and poultry litter are added [19]. In other research [20], fresh orange peel was ensiled without additive (control), or with enzyme inoculate (EI), formic acid (FA), propionic acid (PA) and acetic acid (AA). Samples of fresh and ensiled orange peel were analyzed for dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), *in vitro* dry matter and cell wall disappearance, pH, buffering capacity and ammonia N. In this study, it was concluded that the additives used did not improve nutritional value of orange peel silage. Similarly, it was observed that orange peel silage showed a high apparent digestibility, although additives did not alter nutritive value of silages [21]. In different results, three silages of orange fruit wastes (OFWs) combined with (1) urea (0.5%);

(*C. reticulata*: 17.9%), lemon (*C. limon*: 6.3%) and grapefruit (*C. paradisi*: 5.0%).

levels of ammonia production that caused silage pH increased.

forage in diets for growing-finishing feedlot lambs [14].

utilized as animal feeds for longer periods of time [18].

**3.2. Nutritional value of citrus silage**

fermentation than starch-rich feeds.

TG = Taiwan grass (*Pennisetum purpureum*); PM = poultry manure; HNES = high nitrogen and energy supplement; the latter had (g/kg) ammonium sulfate 18, animal lard 40, cement kiln dust 16, corn 112, cottonseed meal 164, fish meal 42, limestone 32, mineral salts 10, molasses 182, orthophosphate 30, poultry manure 116, rice polishing 160, NaCl 40 and urea 38; within columns, different literals (a or b), denote statistical difference (P<0.05). Adapted with permission from Ortiz-Rubio et al. [9].

**Table 3.** Parameters of ruminal kinetics of sugarcane tops supplemented with different feeds, data obtained from in situ incubations in steers.

Ensiling sugarcane tops is a logical alternative; however, this process may have complications. It is reported that ensiling reduced dry matter digestibility and feed intake in lambs [10], probably because of excessive production of ethanol during the process [11].

Values of 4.7% and 10.1% crude protein, 87% and 78% neutral detergent fiber (NDF), respectively, were reported for fresh and ensiled sugarcane tops [12]; however, this increase in protein could be a dilution effect and not by the fermentative process of ensiling. Acceptable color and odor, indicating no putrefaction was also reported; pH was from 4.0 to 4.04. In vitro gas production was higher for fresh than ensiled sugarcane tops at 24 h; however, the organic matter digestibility estimated from in vitro gas production was higher for ensiled sugarcane tops [12].

It was found that sugarcane tops (SCT) had lower CP and minerals than broiler litter (BL). These two feed ingredients can improve silage nutritional composition, fermentation characteristics, degradation of DM by microorganisms in the rumen and destruction of mycotoxinproducing fungi (MPF). Excessively high amount of BL can cause deleterious effects on the quality of the resulting silage product. It would therefore be recommended that a 30–45% inclusion rate is the most appropriate level of incorporation of BL in silages. Adequate levels of moisture are needed in silage [13]. From 30 to 45% BL enhanced lactic acid production and pH was acceptable; however, 60% of BL in silage resulted in high buffer capacity with high levels of ammonia production that caused silage pH increased.

In a study, sorghum stover was substituted with sugarcane top silage supplemented with urea [0 (T1), 5 (T2) and 10% (T3) DM] in high concentrate diets for feedlot hair lambs. It was observed a reduction of effective ruminal degradability with increased SCT contents in silage. Feedlot hair lambs observed reduced feed intake augmenting sugarcane tops silage in their ration. Nevertheless daily weight gain was not affected by diet. Feed efficiency (gain/feed intake) was not influenced by treatment. It was concluded that ensiled sugarcane tops constitute alternative forage in diets for growing-finishing feedlot lambs [14].
