Effects of physically effective neutral detergent fiber content on dry matter intake, digestibility, and chewing activity in Korean native goats ( Capra hircus coreanae ) fed with total mixed ration

OBJECTIVE: This experiment was to determine proper physical traits in the diet for goats by investigating the effects of physically effective neutral detergent fiber (peNDF) content on dry matter intake (DMI), digestibility, and chewing activity in black goats fed with total mixed ration (TMR). METHODS: Six growing wethers of Korean native black goats (Capra hircus coreanae) aged 8 months and weighing between 26.9 kg and 27.1 kg (27.03±5.05 kg) were used in this experiment. Three diets of varying peNDF content were obtained by original TMR (T1), 12,000 rpm grinding (T2), and 15,500 rpm grinding (T3) of the same TMR diet. The peNDF1.18 content of the experimental diets was 23.85%, 21.71%, and 16.22% for T1, T2, and T3, respectively. RESULTS: Average daily gain (ADG) was higher in T2 group compared to those of the control and T3 groups, but ADG and DMI were not affected by the dietary particle size and peNDF content. Also, there was no difference between apparent nutrient digestibility of dry matter, crude fiber, ether extract, neutral detergent fiber, and acid detergent fiber. Although there was no significant difference, rumination and total chewing time were associated with decreased peNDF content. CONCLUSION: The feeding of peNDF-based TMR showed no impact on apparent nutrient digestibility and nitrogen balance. Further studies are required with a wider range of dietary peNDF level and particle size to better identify the effect of dietary peNDF and particle size on chewing activity and performance in goats.