A Study on the Use of Fecal Characteristics for Feed Digestibility Determination in Goat

This study aimed to explore physical characteristics and its correlation to feed digestibility in goat.Sixteen Ettawah Grade goats in the second milk production periods and in the 4-5th month of lactationwere used in this study. The study was arranged with completely randomized block block design basedon milk production as replications. The goats were fed ration containing 16% of crude protein and 65%of total digestible nutrients (TDN). Some of crude protein content were supplied by urea. The treatmentswere control ration (without urea; T0), ration with 0.4% urea (T1), ration with 0.8% urea (T2), andration with 1.2% urea (T3). Parameters observed were feed digestibility, fecal extended level (FEL), andfecal rough particle distribution (FRPD). Data were analyzed using correlation-regression to find thecorrelation between fecal characteristics and feed digestibility. The results showed that urea content inthe rations up to 1.2% of dry matter did not affect dry mater digestibility, water content and fecalcharacteristics (FEL and FRPD). There were highly negative correlation (r= -0.665) between feeddigestibility and water content of feces as well as feed digestibility and FEL (r= -0.553), whilecorrelation between digestibility and FRDP was positive (r=0.608). The conclusion of this study waswater content, degree of FEL and FRPD can be used to determine the quality of feed. If feces composedof finer texture, dried and small particles indicated having better digestibility, while if feces composed ofrough texture, wet, and large particles indicated having low digestibility.


INTRODUCTION
Goat plays an important role in rural economic due to the easiness of raising, handling and low capital needed. These are some advantages of raising goats, especially dairy goat such as: Ettawah Grade goat in term of the price of goat milk which are relatively more expensive than those of cattle milk. However, up to now the milk production is still low, fluctuated and varied. This condition might be caused by poor anticipation on the change of milk production due to the month of lactation and different feedstuff given during rearing periods which may have different feed utilization. The feed utilization can be determined by its digestibility using digestion trials or indicator methods (Drennan et al., 1970;Weller et al., 1971). These methods are accurate and need several days to determine the feed digestibility, and therefore these methods were not practical.
One of promising methods to determine feed digestibility is by using fecal characteristics. The previous studies on the use of feces have been reported. The science that studies feces, called Scatology, has been done since 1920's (Seton, 1925) by exploring several types of information obtained from feces and their contents, such as for identifying the animal (Camardella et al., 2000), diet composition (Santos andHartz 1999, Kauhala andAuniola 2001), seasonal diet changes (Aragona and Setz 2001), health condition, and potential enteroparasitosis dynamics (Patton et al. 1986, Page et al., 2001. Moreover, recently, feces could be used to determine starch digestion (Fredin et al., 2014;Zinn et al., 2007) as well as organic matter digestion (Lukas et al., 2005).
Theoretically, the more digestible feeds will be more degradable into smaller particles because it will give a better absorption due to wider surface to be penetrated by microbes or digestion enzymes. Remond et al. (2004) found that starch digestibility decreased with the increasing of particle size in their study using corn. This is similar to Lykos and Varga (1995) in their in situ study that reported a linear inverse relationship between the particle size and ruminal digestibility of corn (Lykos and Varga, 1995). Since the particle size of feed is influenced by chewing and rumination activities. This condition could affect the shape, characteristics, and the amount of feces particles that contribute to the characteristics of fecal consistency such as soft, hard, liquid, crushed and so on (Johnson and Taylor, 2001). Based on the above explanation, it can be hypothesized that feces from highly digestible feeds will compose of smaller particle size and bigger extended level of feces than those from lowly digestible feeds. Therefore, this study aimed to explore the correlation between physical fecal characteristics and feed digestibility in order to provide a practical method to monitor feed utilization in animal farming system.

Animals and experimental design
Sixteen lactation of Ettawah Grade goats with initial body weight of 47.2 ± 1.9 kg (CV = 11.9%) at the second lactation periods were used in this study. These goats were in the 4-5 th month of lactation and having milk production range of 100-400 g/day. The goats were raised in an individual metabolic cage equipped with feeder and drinker separately.
The study was arranged with completely randomized block block design based on milk production as replications. The goats were fed ration containing 16% of crude protein and 65% of total digestible nutrients (TDN), Some of crude protein content were supplied by urea. The treatments were control ration (without urea; T0), ration with 0.4% urea (T1), ration with 0.8% urea (T2), and ration with 1.2% urea (T3). Goats were fed a single feed (mixed ration) in mash form with nutrients composition listed in Table 1. Parameters observed were feed digestibility, fecal extended level (FEL), and fecal rough particle distribution (FRPD).

Experimental procedures
The study was conducted in four stages, namely preparation, adaptation, treatment and data collection periods. At preparation stage, the goats were injected with vitamin (Injectamin®) at a dose of 2 mL per 25 kg of body weight to recover from stress during transportation, and administered endo and ectoparasites (Ivomec®) at a dose of 1 mL per 25 kg of body weight to avoid the parasites effect on animal performance.
At the initial adaptation phase, the goats were weighed to determine the nutritional needs based on their body weight. Then, the goats were grouped based on the milk production and randomized to the treatments. Adaptation on feed to determine the goat's feed intake capacity for feeding treatment was lasted for 2 weeks. The feed requirement was calculated based on the nutrients requirements and milk production according to NRC (1981). The treatment periods included data collection were done for 4 weeks.

Digestibility and Fecal Characteristics Measurement
In the last one week, the feed digestibility was measured using 7-days total collection methods. During this period, the feed given, the feed residual and the amount of feces excreted were weighed and sampled daily to determine the dry matter intake and feed digestibility. The calculation was done in dry matter base after all of the materials were oven-dried at 135 o C for 2 hours.
Fecal samples were used to determine the fecal characteristics such as water content, FEL and FRPD. Fecal characteristics were measured using fresh feces (less than 1 hour excreted). The water content of feces was determined by ovendried feces in 135 o C for 2.5 hours. The loss weight between before and after drying process was considered as water, and was calculated in the percentage.
Fecal extended level was measured on 10x1 pieces of goat feces of each treatment which was placed in the modified FEL equipment. The structure and the working procedure of this equipment are illustrated in Figure 1. The works of this tool are: 1) the 500 g or metal load was pull up to 7 cm height from the bottom (the 500 g load's weight and 7 cm height were determined by trial and error prior to fit for application), while 2) the feces was put on the point vertically of the load, and 3) when the load is released and fallen down, the feces will be flattened, and the surface area of feces will be wider. The wide area of feces was measured with millimeter block. The FEL was determined by subtracting the wide area after flattened with the wide area of feces intact. The value of FEL was calculated in the percentage.
The particle distribution of feces was determined by soaking the 25 g of feces in 1000 ml of water for 24 hours prior to be sieved gently to pass 1.0 mm. The feces that cannot pass the 1.0 mm sieve were dried in 135 o C for 2 hours, weighed, and was percentaged to the initial fresh   Feedstuffs  T0  T1  T2  T3 - weight. The value of FRPD was percentaged.

The Effect of Urea Levels on Feed Intake
The intakes of dry matter (DMI) and crude protein (CP) of four feeding treatments are presented in Table 2. The DMI per body weight ranged from 2.71 to 3.12% was classified as normal in goat, being 2.0 to 5.0% of NRC (1981) or 2.0 to 4.7% of Devendra and Burn (1994). Some studies in Angora goats found that the DMI was varied from about 2.33-2.84% BW under intensive rearing system (Trana and Sepe, 2008) to 3.3% of BW in extensive rearing (Bonanno et al., 2008).The DMI per kilogram of metabolic bodyweight (MBW; BW 0.75 ) ranged at 67.38-78.72 g/kg MBW was in normal range of Jamnapari goats which were reported at 40.5-127.3 g/kg MBW (Devendra and Burn, 1983) and 34-104 g/kgMBW (Decandia et al., 2008). Variations of DMI per kilogram body weight were influenced by breeds, feedstuffs composed the feed and feed composition, body weight, maintenance requirements, ambient temperature and seasons (Devendra and Burn, 1994;Decandia et al., 2008).
The dry matter and crude protein intakes in this study were not significant. This result indicated that the urea contained in the ration up to 1.2% of DMI did not affect the palatability. The absence of differences among the treatments in DMI may also possibly due to the ration consisted of the same materials (Table 1) which was confirmed with the statement of Abdulah and Mirajuddin (2005). This study is also agreed to the study of Chanjula and Ngampongsai (2008)   that in the native Thailand crossed goats with Anglo Nubian fed ration containing urea up to 3% DMI did not affect feed consumption and the digestibility.

The Effect of Urea Levels on Feces Characteristics
The results of the DM digestibility of feed, fecal water content, FEL and FRPD of goat are presented in Table 3. The feeding treatments did not give a significant differences on these parameters. This might be caused by the urea concentration in the feed at 0 -1.2% did not affect microbial activity in the rumen fermentation process, therefore it did not cause differences in digestibility, so the substitution of urea to feed protein did not affect feed utilization. Another possible reason for explaining this phenomenon was that the Nitrogen and energy content in the rations were relatively the same in all of the treatments. When the availability of energy in feed was sufficient for rumen microbial activity, the sources of nitrogen feeds (including those derived from urea) did not affect microbial N synthesis as well as in nitrogen balance of goats (Asih et al., 2011). The DM digestibility in this study which ranged at 60.88-62.13% was higher than 55-56% that was reported by Preston and Leng (1987).

The Correlation between Digestibility and Fecal Water Content
The same digestibility value found in this study lead to the similar quality of fecal excreted by goat and give a similar value in FEL and FRPD. One of the factors affecting the FEL was the water content in feces. The data of this study showed that fecal water content was similar, ranging from 61.73 to 64.43%.
The FRPD level of feeding treatment is presented in Table 3. Urea levels in feed did not affect the level of FRPD which was ranged at 21.44 -22.44%. This was related to the feed degradation in the digestive tract indicating that the opportunity of feed to be utilized in the digestive tract.
The correlation between feed digestibility and fecal water content in Ettawah Grade goats are presented in Figure 2. There was a negative correlation (r = -0.665) between DM digestibility (%) and fecal water content (%). The results showed that DM digestibility of feed affected fecal water content, or by another words, the fecal water content indicated the digestibility of feed. From this correlation, the determinant of feed digestibility to fecal water content was 44.3%. This presumably because feces excreted was derived from the same quality diets (Table 1), as proved by the similar DM digestibility (Table 2).
Water content of feces was a major factor that affected the texture of feces. The higher fecal water content made the softer fecal texture. This softer fecal texture would be resulted in faster passage in the digestive tract, and the digestibility will be lower. Fecal water content was influenced by the crude fiber levels of feed. The low crude fiber content in the diet resulted a high dry matter content in feces. In this study, the dry matter digestibility were ranging at 60.88-62.13%, that were higher than 55 -56% observed by Preston and Leng (1987). Meanwhile, the feeds with high crude fiber have a low digestibility (Tillman et al., 1998), and increase the water content of feces (Hafez and Dyer, 1969).

Correlation between Feed Digestibility and Fecal Extended Level
The correlation between DM digestibility (%) and fecal extended level (FEL) (%) is presented in Figure 3. There was a correlation (r = -0.553) between DM digestibility and FEL, with determinant factor of 30.5%. The texture of feces Fecal Characteristics for Feed Digestibility Determination (S.A.B. Santoso et al.) 63 *) All parameters among the treatments were not significant affected FEL. The harder texture produced smaller FEL; otherwise the softer texture produced broader FEL. These results were consistent with the relationship between dry matter digestibility and FEL. Lower digestibility of feed produced lower fecal water content and smaller FEL.

Correlation between Feed Digestibility and Fecal Rough Particle Distribution
The correlation between DM digestibility (x) and fecal rough particle distribution (FRPD) (y) is presented in Figure 4. The correlation of DM digestibility and FRPD observed was positive (r = 0.608). The results showed that DM digestibility affected FRPD level, with determinant factor of 37.0%. This phenomenon could be explained by the process of feed digested in the digestive tracts. Feed was broken down into smaller particle during mastication process in the mouth, then the feed particles move towards esophagus and reticulo-rumen. In the rumen, the feed received a degradation and fermentation process by microbial activity, and in addition, by friction between the feed particles due to rumen motility. The feed particle size met the size of reticuloomasal orifice (the tunnel connected rumen and omasum) will advance go to the omasum, abomasum and intestine (Ulyatt et al., 1986;Poppi et al., 1980), while particle size that still greater than the size of that orifice will be returned to the mouth for remastication to be degraded into smaller size and then was reswallowed. Meanwhile, the FEL was influenced by nutrients and water absorption by small and large intestine, respectively, from material passing through it prior to be excreted as feces (Stevens et al., 1979;Cunningham and Klein, 2007). By assuming that absorption rate was depend on the available nutrients could be absorbed, the nutrients contained in higher digestibility rations will be absorbed more than of the lower digestibility, and in turn proportionally remains higher water content in the feces. Therefore, the feed with a high digestibility will give higher FRPD.

CONCLUSIONS
Fecal water content, fecal extended level and fecal rough particle distribution in Ettawah Grade Goats have a correlation to feed digestibility, therefore, these characteristics could be used to determine feed quality, especially in farm usage. Feces had a finer texture, drier and smaller particles size indicated having better digestibility, otherwise if feces had rough texture, wet, and large particles size indicated having low digestibility. There was a strong negative correlation between DM digestibility with feces water content, and level of FEL, but positive with FRPD goat feces. This study also concluded that level of urea in the ration did not affect the correlation between fecal characteristics and feed digestibility.