*3.3. Apparent Nutrient Digestibility, Digestible Nutrient Intake, and Energy Intake*

Apparent total tract digestibility was affected significantly (*p* < 0.05) by dietary treatments (Table 3). DM, OM, CP, NDF, and ADF digestibility were significantly lower in FDP compared with FDPML. FDPM, FDPC, FDPL, and FDPML were comparable in terms of DM, OM, CP, NDF, and ADF digestibility. Digestible nutrient intake including OM, CP, NDF, and ADF was not different (*p* > 0.05) among treatments. Estimated ME intake, expressed as Mcal/d, was not significant among treatments; however, estimated ME intake, expressed as per kg DM intake, was significant (*p* < 0.05) among treatments. ME intake, expressed as per kg DM intake, was significantly observed between FDP, FDPM and FDPML, in amounts of 2.55 Mcal/kg DM, 2.62 Mcal/kg DM, and 2.69 Mcal/kg DM, respectively.

digestible nutrient intake of growing goats.

Apparent total tract digestibility, %

*Fermentation* **2022**, *8*, x FOR PEER REVIEW 6 of 14

**Table 3.** Effects of untreated and treated discarded durian peel in TMR on nutrient digestibility and

FDPML, respectively. Dietary treatments significantly affected propionate concentration,


**Table 3.** Effects of untreated and treated discarded durian peel in TMR on nutrient digestibility and digestible nutrient intake of growing goats. DM 70.42 b 72.79 a 73.91 a 74.07 a 73.81 a 0.45 <0.01 OM 71.82 b 73.95 a 75.02 a 75.48 a 75.16 a 0.49 <0.01 **Table 3.** Effects of untreated and treated discarded durian peel in TMR on nutrient digestibility and digestible nutrient intake of growing goats.

*Fermentation* **2022**, *8*, x FOR PEER REVIEW 6 of 14

Dietary treatments significantly affected ruminal pH and NH3–N but not ruminal temperature (Table 4). Mean ruminal pH and NH3–N were significantly (*p* < 0.05) observed between FDP and FDPML but FDPM, FDPC, FDPL, and FDPML were comparable. Ruminal pH and NH3–N were 6.71 and 22.58 mg/dL in FDP and 6.44 and 17.29 mg/dL in FDP = untreated discarded durian peel; FDPM = treated discarded durian peel with molasses; FDPC = treated discarded durian peel with cellulase; FDPL = treated discarded durian peel with *L. casei* TH14; FDPML = treated discarded durian peel with molasses and *L. casei* TH14; SEM = standard error of the mean; DM = dry matter; OM = organic matter; CP = crude protein; NDF = neutral detergent fiber; ADF = acid detergent fiber; ME = metabolizable energy. a–c Means in the same row with different letters differ (*p* < 0.05). TH14; FDPML = treated discarded durian peel with molasses and *L. casei* TH14; SEM = standard error of the mean; DM = dry matter; OM = organic matter; CP = crude protein; NDF = neutral detergent fiber; ADF = acid detergent fiber; ME = metabolizable energy. a–c Means in the same row with different letters differ (*p* < 0.05). ⸶ 1 kg DOM = 3.8 Mcal ME/kg [23]. 1 kg DOM = 3.8 Mcal ME/kg [23].

*3.4. Rumen Fermentation Characteristics* 

#### the acetate-to-propionate ratio and acetate—butyrate-to-propionate ratio except total *3.4. Rumen Fermentation Characteristics*

**FDP FDPM FDPC FDPL FDPML Value** 

VFA, acetate, and butyrate concentration. The propionate concentration was significantly higher, while the acetate-to-propionate ratio and acetate—butyrate-to-propionate ratio were significantly lower in FDPML than FDP, FDPM, FDPC, and FDPL. FDPML showed the highest mean propionate concentration (20.31%) and lowest mean acetate-to-propionate ratio (3.58) and acetate + butyrate-to-propionate ratio (3.94). CH4 production was affected significantly (*p* < 0.05) by dietary treatments. Mean CH4 production was significant between FDP and FDPML, at 32.93 g/d and 29.41 g/d, respectively, but FDP, FDPM, FDPC, and FDPL were comparable for CH4 production. Dietary treatments significantly affected ruminal pH and NH3–N but not ruminal temperature (Table 4). Mean ruminal pH and NH3–N were significantly (*p* < 0.05) observed between FDP and FDPML but FDPM, FDPC, FDPL, and FDPML were comparable. Ruminal pH and NH3–N were 6.71 and 22.58 mg/dL in FDP and 6.44 and 17.29 mg/dL in FDPML, respectively. Dietary treatments significantly affected propionate concentration, the acetate-to-propionate ratio and acetate—butyrate-to-propionate ratio except total VFA, acetate, and butyrate concentration. The propionate concentration was significantly higher, while the acetate-to-propionate ratio and acetate—butyrate-to-propionate ratio were significantly lower in FDPML than FDP, FDPM, FDPC, and FDPL. FDPML showed the highest mean propionate concentration (20.31%) and lowest mean acetate-to-propionate ratio (3.58) and acetate + butyrate-to-propionate ratio (3.94). CH4 production was affected significantly (*p* < 0.05) by dietary treatments. Mean CH4 production was significant between FDP and FDPML, at 32.93 g/d and 29.41 g/d, respectively, but FDP, FDPM, FDPC, and FDPL were comparable for CH4 production. Dietary treatments significantly affected ruminal pH and NH3–N but not ruminal temperature (Table 4). Mean ruminal pH and NH3–N were significantly (*p* < 0.05) observed between FDP and FDPML but FDPM, FDPC, FDPL, and FDPML were comparable. Ruminal pH and NH3–N were 6.71 and 22.58 mg/dL in FDP and 6.44 and 17.29 mg/dL in FDPML, respectively. Dietary treatments significantly affected propionate concentration, the acetateto-propionate ratio and acetate—butyrate-to-propionate ratio except total VFA, acetate, and butyrate concentration. The propionate concentration was significantly higher, while the acetate-to-propionate ratio and acetate—butyrate-to-propionate ratio were significantly lower in FDPML than FDP, FDPM, FDPC, and FDPL. FDPML showed the highest mean propionate concentration (20.31%) and lowest mean acetate-to-propionate ratio (3.58) and acetate + butyrate-to-propionate ratio (3.94). CH<sup>4</sup> production was affected significantly (*p* < 0.05) by dietary treatments. Mean CH<sup>4</sup> production was significant between FDP and FDPML, at 32.93 g/d and 29.41 g/d, respectively, but FDP, FDPM, FDPC, and FDPL were comparable for CH<sup>4</sup> production.


**Table 4.** Effects of untreated and treated discarded durian peel on rumen characteristics in growing goats.

FDP = untreated discarded durian peel; FDPM = treated discarded durian peel with molasses; FDPC = treated discarded durian peel with cellulase; FDPL = treated discarded durian peel with *L. casei* TH14; FDPML = treated discarded durian peel with molasses and *L. casei* TH14; SEM = standard error of the mean. a–c Means in the same row with different letters differ (*p* < 0.05).
