1. Introduction

The rumen ecology is basically a fermentation vat that inhabits a huge amount of various microbes [1] [2]. Microbes in the reticulorumen include bacteria, protozoa, fungi, archaea and viruses. The United States Environmental Protection Agency (USEPA) [3] reported that during enteric fermentation in ruminants, methane is produced, the second most important greenhouse gas (GHG) emitted by livestock. The most appropriate technique in the ruminant production nowadays was to understand the rumen ecosystem and determine how to improved and attain the symbiotic relationship of the animals and the rumen microorganisms [4] [5] [6] [7], thus, to improve the digestion efficiency of the rumen microorganism for various feedstuffs.

As a popular tool for studying rumen digestion, degradability and ecology, the nylon bag (in sacco) technique [8] [9] [10] was used. The nylon-bag technique has become more widely used and it is now being recommended as a means for evaluating tropical livestock feeds. However, little work has been done on the practical application of the technique to the evaluation of feeding systems. The use of degradation characteristics as a means of formulating ration combinations for ruminants becomes an aide or guide especially for those nutritionists.

Several researchers employing the nylon-bag technique [11] [12] [13] to study ruminant digestion use a specific basal diet so as to minimize any variations between animals and different trial periods within animals. However, while the results gained do indicate relatively dry-matter digestibility (DMD) of forages, they do not represent natural conditions where the animals are free-ranging and there is variation in basal diets and hence in DMD efficiencies.

2. Materials and Methods

2.1. Care & Management of Animals

The study was conducted at the Metabolism Laboratory of the Institute of Animal and Dairy Sciences Cluster (ADSC), University of the Philippines, Los Baños, College, Laguna, Philippines.

Three (3) mature (rumen-cannulated goats) weighting 27.33 ± 1.53 kg were housed in individual elevated metabolism stalls provided with 30% concentrate in the morning based on feed requirements (3% of their body weight (BW) dry matter (DM) basis) of the animals. Ad libitum feeding of Napier grass follows thereafter. Clean drinking water were made available all the time in the respective animal watering troughs.

Degradability on DM, CP, NDF and ADF were collected sequentially in every cycle of the study. There were seven (7) days lag period in every cycle for the animals to return to each natural state. On the 8th day of every cycle, animals were given different dietary treatment. Sequential insertion of nylon bag was done on the 15th to 16th day (7 days after treatment).

2.2. Research Design and Lay-Out

Three mature goats surgically fitted with rumen cannula were used. The experimental animals were in good body condition prior to and throughout the duration of the study. Complete Randomized Design (CRD) was used to evaluate the effect of different dietary treatments. Five dietary treatments were used in the study with dietary treatment combinations as follows.

2.2.1. Treatment Combinations

The rumen-cannulated goats were supplemented with different levels of two dietary fat sources with dietary treatment combinations as follows (Table 1):

Treatment 1-CONTROL

Treatment 2% - 3% Virgin Coconut Oil (VCO)

Treatment 3% - 5% Virgin Coconut Oil (VCO)

Treatment 4% - 3% Lard

Treatment 5% - 5% Lard

Animal were randomly selected on different dietary treatment at different cycle. For each cycle, animals were provided with Napier grass ad libitum in the

morning and concentrate (30%) in the afternoon. Free access to clean potable water was made available at all time. All data were collected sequentially in every cycle of the study. There were 7 days lag period in every cycle for the animals to return to each natural state.

On the 8th day of every cycle animals were given different dietary treatment. Sequential insertion of nylon bag was done on the 15th to16th day (7 days after treatment).

2.2.2. Laboratory Analysis

Evaluation of Napier grass rumen degradability in sacco in supplemented with different sources and amount of dietary fats were done through different biochemical analysis of different parameters gathered such as.

2.2.3. Experimental Treatment

A total of 48 nylon bags measuring 17 × 10 cm each were prepared with 16 bags each animal. All bags containing around 5 g grounded Napier grass sample were incubated into the rumen following sequential elimination at 0, 3, 6, 9, 12, 24, 36 and 48th hours.

After incubation, the bags were immediately placed in cold water to stop fermentation, and to remove the feed particles adhering to the bags. Then, it was rinsed under running water for about 20 minutes or until the wash water is cleaned. (A good guide to the sample and bag being clean is when the water from a slowly running tap will run out of the bag as quickly as it enters.) The bags are then dried to a constant weight at 60˚C - 70˚C for 24 hours. The washed samples were placed in a desiccator (for 20 - 30 minutes) kept at room temperature. Percent digestion of feedstuff and digestion kinetic parameters is then calculated using the exponential equation:

$D=a+b\left(1-e-ct\right)$

$e-ct=\left(a+b-D\right)/b$

where: D = Degradation (% degradation), a = intercept (soluble fractions), b = potential degradable fraction, c = degradation rate of fraction b, and e = natural logarithm [12].

Representative samples were analyzed for dry matter following the AOAC method; Crude protein using Kjeldahl analysis based on AOAC [14] procedure, Neutral detergent fiber (NDF) and Acid detergent fiber (ADF) analysis were done following the Van Soest and Wine [15] procedure. This was done on the 15th to 16th day of every consecutive cycle.

Data were further subject to NEWAY software analysis to generate data on degradation and regression fit curve.

3. Result and Discussion

3.1. DM Degradability

The dry matter degradability of Napier grass after incubation for each incubation period (0, 3, 6, 9, 12, 24, 36 and 48 hours) in goats fed with varying levels of dietary fats (coco oil and lard) in the concentrate was presented (Figure 1) showed that degradability of the dry matter (DM) content of the Napier was found to be 72.30% at 48 hrs of incubation. The 68% potentially degradable fraction has a rate of degradation (disappearance) at 49%.

After 48 hours of incubation, control got the highest degradation with 49.170% followed by treatment given with VCO (5%), Lard (5%), Lard (3%), and VCO (3%) with 48.77, 48.14, 40.38, and 39.47 percent, respectively.

It was also observed that the percentage degradability (% loss) of DM was noticed exponentially on the first twelve hours of incubation and slower down on the next few hours until 48 hours. Result ranges from 39% - 49% dry matter degradability however, no significant difference (P > 0.05) among treatment means was observed on dry matter degradability. This may imply that rumen microorganism did not utilize the dry matter content of Napier grass efficiently. However, it may also indicate that extending the incubation in the rumen makes the sample totally degraded by rumen microbes [1] [2].

Napier grass dry matter disappearance in the rumen at various incubation time in goat fed different dietary fats (Table 2) showed that different treatment

¹ = Effective degradability; a = Solubility or readily soluble fraction; b = slowly soluble fraction; a + b = potentially digestible fraction; c = Degradation rate constant; CO = Coconut oil; L = Lard; NGC = animal feed at 3% BW (70% Napier grass + 30% concentrate); NGC + 3% = animal feed at 3% BW + 3% dietary fat on the concentrate; NGC + 5% = animal feed at 3% BW + 5% dietary fat on the concentrate.

soluble fractions (a) ranges from 17.2% - 20.8% with the highest readily soluble fraction from treatment supplemented with lard (3%) and the lowest was coming from the control. Readily soluble fractions were high on fat supplemented compare from control. However, the soluble fraction of Napier grass DM in rumen of female mature goat was not significantly (P > 0.05) differ with dietary fat supplementation.

The insoluble but potentially fermentable fraction (b) of Napier grass DM decreased with fat supplementation. The insoluble but potentially fermentable fraction of Napier grass on rumen of goat with fat supplementation on Control, VCO (3%), Lard (5%), VCO (5%), Lard (3%) were 52.7%, 47.1%, 44.0%, 40.3% and 24.5%, respectively.

Adding of dietary fat on the concentrate decreases the potential fermentable fraction of Napier grass. This could be due to the decrease of microbial population present in the rumen during fat supplementation. Addition of fat will result to depression in fiber digestion in the rumen [16] [17]. Also, saturated fatty acids such as coconut oil have been shown to have a toxic effect on protozoa and methanogens [16] [18]. In similar study feeding 3.5% and 7% coconut oil reduced ciliate protozoa to [1.0 (105 ml/li) and 0.3 (105 ml/li)], respectively, compared to no oil supplementation [1.7 (105 ml/li)] [18].

Potentially digestible fraction (a + b) on the goat rumen at various incubation time supplemented with different dietary fats on the concentrate ranges from 45.0% - 69.9% with a highest potentially digestible fraction from control groups while the lowest was coming from Lard (3%) (Figure 2).

Degradation rate of DM of Napier grass in the rumen showed that Control got the lowest degradation rate of 0.031 followed by VCO (5%), Lard (5%), VCO (3%), and Lard (3%) of 0.036, 0.049, 0.06 and 0.122, respectively. No significant difference (P > 0.05) across treatments at different incubation period in terms of DM degradation rate of Napier in the rumen of goat supplemented with different dietary fats was observed.

Effective degradability at 0.02, 0.05 and 0.08 outflow rate/hour was tabulated to evaluate the effect of different dietary fats on the degradability of Napier grass at specific outflow rate/hour. Data showed that goat fed with VCO (5%) got the highest effective degradability followed in decreasing order of treatments, Lard (5%), Control, Lard (3%) and VCO (3%). Despite of difference on outflow rate/hour at 0.02, 0.05 and 0.08, no significant difference (P > 0.05) were observed on among treatment means on outflow rate/hour.

Goat supplemented with 5% fats got the better effective degradability of Napier grass whereas the 3% supplemented group got the meager result. Despite variation on different treatments given, no significant difference (P > 0.05) observed across treatments at different incubation period. This implies further that adding dietary fat on the concentrate as high as 5% does not influence the goat’s degradability performance of Napier grass.

3.2. Crude Protein Degradability

Crude protein degradability of Napier grass after incubation period (0 h, 3 h, 6 h, 9 h, 12 h, 24 h, 36 h and 48 h) in goats fed with varying levels of dietary fats (coco oil and lard) presented (Figure 3) showed that after 48 hours of incubation, VCO (5%) got the highest crude protein degradation with 7.110% followed by control group, Lard (5%), Lard (3%), VCO (3%) with 7.0, 6.4, 5.6 and 5.1 percent, respectively. However, the differences between treatments failed to satisfy the P < 0.05, hence all treatment means for crude protein degradability were comparable.

The crude protein (CP) degradability resulted to 60.98% of the 11.66% CP content of the Napier grass, a 7.11% breakdown of protein components after 48 hrs of incubation. Although more than 17.36% was observed between the lowest to highest CP degradability after 48 hours, no significant difference (P > 0.05) among treatment means was observed., This implies that supplementing 3 to 5% dietary fats from two different sources (VCO and Lard) in ruminant diet do not influence the crude protein degradability of mature female goats.

The result deviate on the study of Henry [19] and Dawson [20] that crude protein is 97% digestible those aided rumen microbes for reproduction and good

digestion. The deviation of the result could be due to limited number of exposed time of forage material to the microbes in the rumen. Ørskov and McDonald [12] stated that potential degradability of roughages degraded in the rumen for about 70 hours.

Napier grass dry matter disappearance in the rumen at various incubation time in goat fed different dietary fats (Table 3) showed that different treatment soluble fractions (a) ranges from 15.967% - 19.367% with the highest readily soluble fraction from NGC + CO (5%) and the lowest was coming from the control group. Readily soluble fractions were apparently higher on fat supplemented compare from control group. However, the soluble fraction of Napier grass crude protein in rumen of goat was not significant influenced dietary fat supplementation. The insoluble but potentially fermentable fraction (b) of Napier grass CP decreased with fat supplementation except for VCO (5%) treatment with 80.6% potential fermentable fraction followed by control with 69.1%, followed by Lard (5%) of 51.5%, followed by VCO (3%) of 45.4% and the lowest insoluble but potentially fermentable fraction was coming from Lard (3%) of 39.4%.

Potentially digestible fraction (a + b) on the goat rumen at various incubation time supplemented with different dietary fats on the concentrate ranges from 57.933 to 100.000% with a highest potentially digestible fraction from NGC + CO (5%) while the lowest was coming from NGC + L (3%).

Results also revealed that there is no significant difference (P > 0.05) across treatments at different incubation period in terms of CP potentially digestible fraction. No interaction effect on fat source, level and block was observed. The result emphasized that adding of fats (coco oil and lard) as high as 5% do not influence the changes in potentially digestible fraction of CP of Napier grass in the rumen.

Degradation rate of CP of Napier grass in the rumen showed that 3% fat supplementation group got the highest degradation rate of 0.063 followed by VCO (5%), control, Lard (5%), of 0.029%, 0.020%, and 0.003%, respectively. No

¹ = Effective degradability; a = Solubility or readily soluble fraction; b = slowly soluble fraction; a + b = potentially digestible fraction; c = Degradation rate constant; CO = Coconut oil; L = Lard; NGC = animal feed at 3% BW (70% Napier grass + 30% concentrate); NGC + 3% = animal feed at 3% BW + 3% dietary fat on the concentrate; NGC + 5% = animal feed at 3% BW + 5% dietary fat on the concentrate.

significant difference (P > 0.05) across treatments at different incubation period in terms of CP degradation rate of Napier grass in the goat rumen supplemented with different dietary fats on the concentrate was been observed although there were variations on the resulting data, statistics showed insignificant. Data revealed that no interaction effect on between fat source, level and replication. The result further emphasized that adding of fats (coco oil and lard) as high as 5% do not influenced the changes in CP degradation rate of Napier grass in the rumen (Figure 4).

Effective degradability at 0.02, 0.05 and 0.08 outflow rate/hour was tabulated to evaluate the effect of different dietary fats on the degradability of Napier grass at specific outflow rate/hour. Data showed that goat fed with VCO (5%) got the highest effective degradability followed in decreasing order of treatments, Control, Lard (5%), Lard (3%), and VCO (3%).

Goat supplemented with 5% fats got the better effective degradability of Napier grass whereas the 3% supplemented group got the lowest result. Despite of variation on different treatments given, no significant difference (P > 0.05) observed across treatments at different incubation period. This implies further that adding dietary fat on the concentrate as high as 5% do not influence the crude protein degradability performance of Napier grass on goat.

3.3. Neutral Detergent Fiber Degradability

Neutral detergent fiber degradability of Napier grass after incubation period (0 h, 3 h, 6 h, 9 h, 12 h, 24 h, 36 h and 48 h) in goats fed with varying levels of dietary fats (coco oil and lard) (Figure 5) showed that after 48 hours of incubation, Control got the highest neutral detergent fiber degradation with 18.43% and the lowest was coming from Lard (3%) of 11.84% (Figure 6).

The neutral detergent fiber degradability (NDF) resulted to 27.03% of the 68.21% of NDF content of Napier grass, a 18.43% breakdown of neutral detergent fiber components after 48 hours. Although there were 11.42% difference from the highest to the lowest NDF degradability after 48 hours, no significant

difference (P > 0.05) among treatment means was observed., This implies that mature female goat diet cannot be influenced by dietary fats from two different sources (VCO and Lard) at 3% to 5% supplementation. This shows that rumen microorganism partly utilized the NDF content of Napier grass efficiently. On the other hand, extending the incubation in the rumen can increase the degradability of Napier grass by rumen microbes [1] [2].

Napier grass neutral detergent fiber disappearance in the rumen at various incubation time in goat fed different dietary fats on the concentrate (Table 4) showed that different treatment NDF soluble fractions (a) range from 3.8% - 5.9% with the highest readily soluble fraction from VCO (5%) and the lowest was coming from the control group. Readily soluble fractions were high on fat supplemented compare from the control group. However, the soluble fraction of Napier grass crude protein in rumen of goat was not significant (P > 0.05) influenced dietary fat supplementation.

¹ = Effective degradability; a = Solubility or readily soluble fraction; b = slowly soluble fraction; a + b = potentially digestible fraction; c = Degradation rate constant; CO = Coconut oil; L = Lard; NGC = animal feed at 3% BW (70% Napier grass + 30% concentrate); NGC + 3% = animal feed at 3% BW + 3% dietary fat on the concentrate and NGC + 5% = animal feed at 3% BW + 5% dietary fat on the concentrate.

The NDF insoluble but potentially fermentable fraction (b) of Napier grass on the was high on the treatment without supplementation of 96.2% followed by Lard (5%) of 79.8%, followed by VCO (3%) of 65.3%, followed by VCO (5%) with 38.1% and the lowest insoluble but potentially fermentable fraction was coming from Lard (3%) of 31.7%. Adding of dietary fat on the concentrate lowers the potential fermentable fraction of Napier grass NDF in the rumen. Despite 64.5% difference, result showed no significant difference (P > 0.05) among treatment means was observed.

Neutral detergent fiber potentially digestible fraction (a + b) of Napier on the goat rumen at various incubation time supplemented with different dietary fats on the concentrate ranges from 37.5% to 100% with a highest potentially digestible fraction from the control while the lowest was coming from Lard (3%).

Results also revealed that there is no significant difference (P > 0.05) across treatments at different incubation period in terms of NDF potentially digestible fraction.

Degradation rate of NDF of Napier grass in the rumen showed that VCO (5%) got the highest degradation rate of 14.2% followed by Lard (3%), VCO (3%), Lard (5%) and control with 3%, 2.8%, 0.4% and 0.3%, respectively. NDF degradation rate of Napier grass showed no significant difference (P > 0.05) across treatments at different incubation period. Although there were variations on the resulting data, statistics showed insignificant. The result further emphasized that adding of fats (coco oil and lard) as high as 5% do not influence the changes in NDF degradation rate of Napier grass in the rumen.

Effective degradability at 0.02, 0.05 and 0.08 outflow rate/hour was tabulated to evaluate the effect of different dietary fats on the degradability of Napier grass at specific outflow rate/hour. Data showed that control got the highest effective degradability while VCO (3%) showed the lowest. Comparing the supplemented group, goat supplemented with 5% fats got the better effective degradability compared from the 3% supplemented group but despite variation on different treatments given, no significant difference (P > 0.05) observed across treatments at different incubation period. This implies further that adding dietary fat on the concentrate as high as 5% do not influence the NDF degradability performance of Napier grass on goat.

3.4. Acid Detergent Fiber Degradability

Neutral detergent fiber degradability of Napier grass after incubation period (0 h, 3 h, 6 h, 9 h, 12 h, 24 h, 36 h and 48 h) in goats fed with varying levels of dietary fats (coco oil and lard) on the concentrate was presented (Figure 7) shows that after 48 hours of incubation. The acid detergent fiber degradability (NDF) resulted to 31.71% of the 38.04% of NDF content of Napier grass, a 12.06% breakdown of acid detergent fiber components after 48 hours. Although ADF degradability ranges from 18.3% - 31.7% with 13.4% difference from the highest to the lowest ADF degradability after 48 hours, no significant difference (P > 0.05) among treatment means was observed., This implies that mature female goat diet cannot be influenced by dietary fats from two different sources (VCO and Lard) at 3% to 5% supplementation. This shows that rumen microorganism was partly utilized the ADF content of Napier grass efficiently. On the other hand, extending the incubation in the rumen can increase the degradability of Napier grass by rumen microbes [1] [2].

Results show that there is no significant difference (P > 0.05) across treatments at incubation period at 0, 6, 9, 12, and 24 hours of incubation. On the other hand, significant differences (P < 0.05) were observed at 36 h and 48 h of incubation. No differences were observed between control and treatments supplemented with 5% dietary fats while control and 3% dietary supplementation showed significant difference (Figure 8).

Napier grass ADF disappearance in the rumen at various incubation time in goat fed different dietary fats on the concentrate (Table 5) showed that different treatment ADF soluble fractions (a) range from 4.3% - 6.8% with the highest readily soluble fraction from VCO (5%) and the lowest was coming from the control. Readily soluble fractions were high on fat supplemented compare from

¹ = Effective degradability; a = Solubility or readily soluble fraction; b = slowly soluble fraction; a + b = potentially digestible fraction; c = Degradation rate constant; CO = Coconut oil; L = Lard; NGC = animal feed at 3% BW (70% Napier grass + 30% concentrate); NGC + 3% = animal feed at 3% BW + 3% dietary fat on the concentrate and NGC + 5% = animal feed at 3% BW + 5% dietary fat on the concentrate.

control group. However, the ADF soluble fraction of Napier grass in rumen of goat was not significant (P > 0.05) influenced dietary fat supplementation.

The ADF insoluble but potentially fermentable fraction (b) of Napier grass decreases upon increasing the amount of coconut oil on the concentrate while inversely result on lard supplemented group.

Acid detergent fiber potentially digestible fraction (a + b) of Napier on the goat rumen at various incubation time supplemented with different dietary fats on the concentrate showed control as the highest with 100.0% followed by Lard (5%), VCO (3%), VCO (5%) and Lard (3%) with 95.2, 70.8, 47.9 and 32.7 percent, respectively. Results also revealed that a 67.3% difference showed no significant difference (P > 0.05) among treatments means at different incubation period.

Degradation rate of ADF of Napier grass in the rumen showed that Lard (3%) got the highest degradation rate while control to be the lowest group. No significant difference (P > 0.05) across treatments at different incubation period. Effective degradability at 0.02, 0.05 and 0.08 outflow rate/hour on the other hand showed that control got the highest effective degradability while VCO (3%) showed the lowest. Comparing the supplemented group, 5% dietary fats supplementation got the better effective degradability compared to the 3% supplemented group. Despite variation on different treatments given, no significant difference (P > 0.05) observed among treatment means at different incubation period. This implies further that adding dietary fat on the concentrate as high as 5% do not influence the ADF effective degradability performance of Napier grass on goat.

4. Conclusion

Based on the study conducted, dietary fats supplementation on goats such as VCO and lard given at the maximum level of 5% level did not influence the nutrient degradability of Napier grass in the rumen until it reaches at 48 hours of incubation. Supplementing ruminant diets with dietary fat in goats could increase the energy density of the animal’s diet without adverse effect on rumen degradability.

Acknowledgements

The Filipino people and its administering agencies such as DOST/PCAARRD/SEI, through the Accelerated Science & Technology Human Resource Development Program for the graduate scholarship;

To my advisory committee for their guidance, advices and recommendations and to Dr. Antonio A. Rayos, for conducting rumenotomy on the experimental animals.

To all staff of Animal Nutrition Laboratory, University of the Philippines Los Baños, for their kind assistance during this study.

To my family for the inspiration, encouragement and financial support to finish this study.

To all my professors in UPLB, for the valuable knowledge you’ve shared and for pushing me to work harder and strive for excellence.

To the UPLB Graduate School staff, for their guidance and kind help.