**5. Effects on the animal's nutrition and health**

As mentioned previously, fiber is not considered an essential nutrient for animals. Although its consumption can be beneficial for reducing energy intake, promoting satiety, supporting gut health, and hairball management [26, 49–55].

Fiber can be of particular interest for the health and wellbeing of cats as they are known to suffer from hairballs. Hairballs, also known as trichobezoars, are hair masses formed in the cat's stomach due to the extensive period of time they groom themselves [54, 56, 57] and some anatomical [57, 58] and physiological adaptations [59]. As a result of these idiosyncrasies, cats can accumulate hair in the stomach and regurgitate it when the mass is too big to pass to the duodenum. In addition, there are reports of intestinal blockages caused by trichobezoars [60]. It is believed that the addition of fiber in the diet can decrease or eliminate this issue. For example, [61] patented (patent number US 7,425,343 B2) the use of high fiber concentrations in the diet for the purpose of improving gastric motility in an effort to pass the trichobezoars to the small intestine and(or) increase the gastrointestinal passage rate. Other fibers have been evaluated as well [5, 54, 62, 63] with variable success. Their inconsistent results may be related to different methodologies used for evaluation of animal responses and the types of fiber used. Clearly, any comparison between studies must be approached with caution and more studies are needed to determine the effects of fiber in hairball management in cats. Miscanthus grass was evaluated as a fiber source to aid in hairball management in cats [5]. In this research trial, 12 American short-hair cats were fed a control diet and a test diet in which Miscanthus grass was added at 10% in exchange of rice flour. The cats were fed the diets for 21 days (16 adaptation days plus 5 days of total fecal collection) with fresh water available throughout the duration of the trial. In addition, cats were brushed prior to the start of each feeding period of a switch-back study design to remove loose hair. It was observed that less hair clumps and total hair weight were excreted per gram of dry feces in cats fed the Miscanthus grass diet. While these results were somewhat expected, because more dry feces was evacuated by cats fed Miscanthus grass, it also provided an indication that fibers (in this case Miscanthus grass) could be used in hairball management in cats as a matter of hair dilution and (or) separation to avoid aggregation. However, it is crucial to state some of the limitations of this trial, such as the use of cats that did not have a history of hairballs and had short hair. Future studies should consider evaluation by cats that have a history of hairballs, have longer hair, and the feeding period should be longer (since regurgitation frequency of a hairball could be monthly) in order to gain a true assessment of hairball elimination.

In similar fashion, weight management, food acceptance, digestibility, fecal consistency and defecation frequency, and colonic fermentation are also affected by the type of fiber. A variety of fiber ingredients are currently used in food production or for supplements intended for both humans and their pets. In general, it is

#### *Miscanthus Grass as a Nutritional Fiber Source for Monogastric Animals DOI: http://dx.doi.org/10.5772/intechopen.99951*

known that obesity can lead to major chronic health issues for humans and pets [53, 64–68]. In theory weight loss by calorie restriction or alternatively an increase in energy expenditure is a simple principle, but in practice it is much more complicated as evidenced by the growing numbers of obese individuals [24] and pets [23]. Dietary fiber ingredients can contribute to caloric restriction and increase the perception of satiety [49, 69]. Unfortunately, dietary fiber addition is also known to decrease acceptance or palatability of a food [27, 70, 71] which contributes to the relatively low success of weight loss/management programs.

Other benefits of fiber in the diet are related to the production of fermentation products in the colon that promote health through the production of post-biotics, especially the short chain fatty acid butyrate. The benefits of butyrate for human health have been extensively reviewed elsewhere [25, 72]; however, there is still the need to verify most of these benefits for pets. The rate of fermentation and the amount of each SCFA is dependent on the fiber source [51, 52, 73, 74]. Thus, if the fiber source is concentrated in soluble and fermentable fibers rather than insoluble and non-fermentable fibers, more SCFA will be produced [75–77]. Miscanthus grass has been evaluated in an in vitro fermentation model using canine feces as an inoculum [3] and its fermentation was comparable to cellulose, an insoluble and non-fermentable fiber source. As a result, Miscanthus grass may not be an effective prebiotic in companion animal diets. Finet et al. analyzed total phenols and indoles, short- and branched-chain fatty acids, and ammonia in fecal samples of cats after they were fed a diet containing 9% Miscanthus grass for 21 days. The authors reported that cats fed Miscanthus grass diet had a higher excretion of indoles compared to cats fed either beet pulp (11% inclusion) or cellulose (7% inclusion). Additionally, acetate and propionate fecal concentrations were also lower compared to cats fed the beet pulp diet; however, no changes in butyrate, branched-chain fatty acids, and ammonia were reported [7]. The addition of Miscanthus grass to feline diet at 9% increased alpha diversity compared to beet pulp supplemented diet when considering Faith's phylogeny and Shannon entropy index [7]. This suggests that while not as substantially fermented compared to other fiber sources, there may be some soluble and fermentable substrate in Miscanthus grass that could benefit the animal if provided at a sufficient dose.

By definition fiber escapes upper gastrointestinal tract digestion and would be available for fermentation in the colon. With more fiber in the diet, dry matter, organic matter, and energy digestibility of foods would decrease [78]. This contributes to dietary energy dilution, especially for insoluble fibers. Dogs [2] and cats [5] fed diets containing 10% Miscanthus grass each had decreased dry matter, organic matter and total dietary fiber digestibility compared to animals fed diets containing a similar level of beet pulp. That [7] did not see an effect of Miscanthus grass (9% inclusion) on dry matter, organic matter, and energy digestibility of dried cat foods compared to those fed diets containing beet pulp is a bit of a mystery. When diets containing 3% Miscanthus grass were fed to broiler chicks, gross energy and apparent metabolizable energy digestibility were lower compared to chickens fed beet pulp diets [1] without changes in dry matter and organic matter digestibility reported. A summary of the digestibility studies published in which Miscanthus grass was a primary fiber source for monogastric animals can be found in **Table 2**.

While this is expected, for some animal industries (*e.g.*, swine and poultry) the addition of fiber is considered to be a nutrient dilution which is undesirable and kept to a minimum. However, there is some indication that addition of fiber ingredients could be beneficial for poultry production and might decrease or replace the use of antibiotics as growth promoters by stimulating the growth of beneficial gut bacteria [80–82]. Further, Miscanthus grass might not qualify as a prebiotic, but its coarse physical characteristics in the feed provided to chicks may stimulate gizzard


*1 From Donadelli et al. [1]; values are averages of tested life stages and the two different tested Miscanthus grass particle sizes.*

*2 From Donadelli and Aldrich [2].*

*3 From Donadelli and Aldrich [5].*

*4 From Finet et al. [7]; fecal scores converted to a similar scale to the other studies.*

*5 According to Carciofi et al. [79]; 1 = liquid diarrhea, 5 = hard pellets.*

*n/a: not available.*

#### **Table 2.**

*Summary of digestibility and stool quality animal studies with Miscanthus grass as a dietary fiber source.*

contractions which is known to stimulate digestive secretions. This may improve nutrient digestibility and limit bacterial growth in the proventriculus with hydrochloric acid release [82].

Fiber ingredients can aid fecal consistency and defecation frequency; however, their effects are source and dose dependent [26, 83, 84]. When fed to dogs and cats, the addition of dietary Miscanthus grass did not affect defecation frequency; however, fecal dry matter was higher for animals fed Miscanthus grass [2, 5] compared to pet fed beet pulp. Moreover, feces of dogs and cats fed Miscanthus grass were harder than animals fed beet pulp.

One benefit that Miscanthus grass could have in human health is the control of cholesterol levels. Lignin was shown to have hypocholesterolemic effects in mice [85]. While Miscanthus grass still needs to be evaluated in humans, this could be another use of this fiber source.
