Effects Of Neutral Detergent Fiber Composition Of Ryegrass And Particle Size On Eating Behavior, Ruminal Fermentation And Rumen Degradation Kinetics Of Goats

On the research foundation of our studying team , this experiment was conducted to study the effect of ryegrass composition of neutral detergent fiber (NDF) and particle size on eating behavior, ruminal fermentation and rumen degradation kinetics of goats. To provide theoretical basis for effectively evaluated feed nutritive value and reasonablly composed rumen diet.Four [(40.0±1.8) kg BW] ruminally cannulated goats were used in the experiment, and they were housed in individual metabolism crates (0.75 m×1.5 m). The goats were feeding twice daily at 0800 and 2000 h for ad libitum intake. The full-bloom stage or initial bloom stage ryegrass was the only forage in this experiment, and four diets all contained 24.19% FNDF. The The experiment was designed as two factors 4×4 Latin square. Factor 1 was the ryegrass NDF composition (NDFlow lignin and NDFhigh lignin). Factor 2 was the ryegrass particle size (chopped 20 mm and ground 5 mm). Four experimental diets were NDFlow lignin20, NDFlow lignin5, NDFhigh lignin20 and NDFhigh lignin5 Each period consisted of 13 d of adaptation to diets and 7 d of experimental measurements. The next period start immediately after one period fininshed.The main results are as follows:1.Ryegrass composition of NDF and particle size both significantly effected ryegrass particle size distribution(P<0.05). Ryegrass particle size significantly effected dietary particle size distribution.(1) The peNDF8.0 and peNDF1.18 in NDFhigh lignin group was significantly higher than those in NDFlow lignin group(P<0.05);(2) Increasing ryegrass particle size significantly increased dietary pef8.0, pef1.18, peNDF8.0 and peNDF1.18, but significantly decreased the proportion of DM on the pan(P<0.05), significantly increased the proportion of DM on the 19.0 and 8.0 mm sieves, but decreased the proportion of DM on the 1.18 mm sieve(P<0.05);(3) There was a significant interaction between ryegrass particle size and composition of NDF in dietary peNDF8.0 content (P<0.05). 2 Ryegrass composition of NDF and particle size both significantly effected eating behavior.(1) NDFhigh lignin ryegrass tended to increase ruminating time per unit of DM or peNDF1.18 and chewing time (min/kg of peNDF1.18) (0.05<P<0.1), and significantly increased chewing time per unit of DM or peNDF1.18(P<0.05);(2) Decreasing ryegrass particle size significantly increased dry matter intake (DMI), extra significantly increased eating time (min/d and min/kg of peNDF8.0), chewing time (min/kg of peNDF8.0) and ruminating time (min/kg of peNDF8.0), but extra significantly decreased chewing time (min/d), ruminating time (min/d) and eating time (min/kg of DM, min/kg of NDF and min/kg of peNDF1.18)(P<0.01);(3) NDFhigh lignin dietary increased the sorting activity(SA) of diet in 19.0 mm sieves for goats(P<0.05). Reducing ryegrass particle size increased the SA of diet in 8.0 and 1.18 mm sieves and decreased the SA of pan for goats. The goats were preferential consumption for diet DM retained on 19.0, 8.0 and 1.18 mm sieves(SA>100), while disliked diet DM retained on pan(SA<100).3 Increasing the content of lignin in the NDF of ryegrass and ryegrass particle size both significantly improved ruminal pH, but decreased the ruminal VFA concentration; Different treats had different effect on rumen cellulase activity.(1) NDFhigh lignin ryegrass significantly increased mean ruminal pH, significantly decreased the time that the pH was below 6.0(P<0.05) and the ruminal VFA concentration from 97.85(NDFlow lignin20) and 116.71(NDFlow lignin5) to 92.56(NDFhigh lignin20) and 100.74(NDFhigh lignin5) mM(P<0.05);(2) Increasing particle size significantly increased mean ruminal pH and ruminal VFA concentration(P<0.05), but tended to decreased acetate concentration (0.05<P<0.1), significantly decreased the time that the pH was below 6.0(P<0.05) and tended to decreased the time that the pH was below 5.6(0.05<P<0.1);(3) NDFhigh lignin dietary significantly increased the activity of ruminal Crystal cellulose hydrolytic enzyme of goat at 12 and 16 hours, Salicin hydrolytic enzyme at 4 hours and Xylanase enzyme at 8 hours after feeding(P<0.05). Ground ryegrass significantly decreased the activity of Crystal cellulose hydrolytic enzyme at 8 and 16 hours, CMC hydrolytic enzyme at 8 hours and Salicin hydrolytic enzyme at 16 hours (P<0.05). The rumen cellulase activity had the same change trend, all decreased at first and then increased. The activity of Crystal cellulose hydrolytic enzyme, CMC hydrolytic enzyme and Salicin hydrolytic enzyme all achieved to the lowest at 4 hours after feeding, while had a different highest level.4 Ryegrass composition of NDF and particle size both significantly effected rumen degradation kinetics of goats.(1) NDFlow lignin dietary extra significantly increased a and P value of ryegrass DM and NDF and a, c and Lt value of concentrates'mixture(P<0.01), but extra significantly decreased c value of ryegrass DM and Lt value of ryegrass NDF(P<0.01), and significantly increased b value of concentrates'mixture. NDFlow lignin dietary also tended to increase P value of concentrates'mixture and c value of ryegrass NDF(0.05<P<0.1);(2) Increasing ryegrass particle size significantly increased Lt value of ryegrass DM and extra significantly increased c value of concentrates'mixture and a value of ryegrass NDF(P<0.01). The interaction effect of ryegrass composition of NDF and particle size extra significantly influenced on c value of concentrates'mixture and a value of ryegrass NDF(P<0.01), influenced significantly on c value of NDF(P<0.05) and had the trend to Lt value of NDF(0.05<P<0.1).In the experience, this study showed that increasing ryegrass particle size and the lignin in the NDF both significantly improved eating behavior, ruminal pH and the activity of Crystal cellulose hydrolytic enzyme at 16 hours and Salicin hydrolytic enzyme at 4 hours after feeding. but which reduced VFA. Increasd ryegrass particle size reduced DMI.