Influence of Dietary Forage Neutral Detergent Fiber on Ruminal Fermentation, Chewing Activity, Nutrient Digestion, and Ruminal Microbiota of Hu Sheep
by
,
Zhian Zhang
1,
Fei Li
1,*,
Fadi Li
1,
Zongli Wang
1,
Long Guo
1,
Xiuxiu Weng
1,
Xuchun Sun
2,
Zhenhu He
3,
Xianyu Meng
4,
Zhaoqing Liang
5 and
Xiong Li
6 1
State Key Laboratory of Grassland Agro-Ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
2
Linxia Animal Husbandry Technical Extension Station, Linxia 731199, China
3
Linxia County Animal Husbandry Development Centre, Linxia 731804, China
4
Dongxiang County Animal Husbandry Development Centre, Linxia 731199, China
5
Linxia State Xiaokangcun Feed Co., Linxia 731801, China
6
Hezheng County Animal Husbandry Development Centre, Linxia 731299, China
*
Author to whom correspondence should be addressed.
Animals 2025, 15(3), 314; https://doi.org/10.3390/ani15030314
Submission received: 3 January 2025
/
Revised: 19 January 2025
/
Accepted: 21 January 2025
/
Published: 23 January 2025
(This article belongs to the Special Issue Maximizing Fiber Utilization for Sustainable, Efficient Ruminant Production)
Simple Summary
The role of dietary forage neutral detergent fiber in maintaining rumen function is critical for ruminants, yet it remains unclear what an optimal proportion of forage neutral detergent fiber that is suitable for sheep is in the pelleted total mixed ration feeding model. This investigation aimed to explore the influence of dietary forage neutral detergent fiber on ruminal pH, fermentation characteristics, chewing activity, nutrient digestibility, and the ruminal bacterial community of Hu sheep fed a pelleted total mixed ration. The results showed that increasing dietary forage neutral detergent fiber content shifted the rumen fermentation pattern towards acetate production, reduced lactate concentration in the rumen, and stimulated both chewing and ruminating, thereby mitigating the severity of subacute rumen acidosis in sheep. Additionally, increasing dietary forage neutral detergent fiber content increased the proliferation of cellulolytic bacteria in the rumen, and it promoted fiber utilization. A ratio of forage neutral detergent fiber (12.48%) to rumen-degradable starch (15.57%) with 0.8 was found to be optimal for maintaining stable ruminal function.
Abstract
As the key components of dietary carbohydrates, ensuring a balance between forage-neutral detergent fiber (FNDF) and rumen-degradable starch (RDS) is essential for ruminant health. Eight male Hu sheep equipped with rumen cannulas were randomly divided into four groups based on dietary FNDF content: low FNDF (L-FNDF, 6.08%), middle low FNDF (ML-FNDF, 9.47%), middle high FNDF (MH-FNDF, 12.48%), and high FNDF (H-FNDF, 15.68%), while the RDS levels (15.65% of DM on average) were similar among the four groups. A replicated 4 × 4 Latin square design was employed in this study. The results indicated that mean and minimum ruminal pH increased linearly with increasing dietary FNDF content, while the duration and area of pH under 5.8 and 5.6, along with the acidosis index, reduced linearly (p ≤ 0.002). There were no differences between the MH-FNDF group and the H-FNDF group in these indicators (p > 0.05). The molar proportions of acetate, butyrate, isobutyrate, and isovalerate, as well as the acetate-to-propionate ratio, increased linearly, while propionate and valerate molar proportions and lactate concentration displayed a linear decrease with increasing FNDF content in the diet (p < 0.001). Increasing dietary FNDF content extended ruminating and chewing time while enhancing ruminal microbial diversity, promoting the proliferation of Fibrobacterota and Butyrivibrio in the rumen, and improving fiber degradability (p < 0.05). When the dietary FNDF content exceeded 12.48%, no effects of FNDF on acetate to propionate ratio and fiber utilization were observed (p > 0.05). The results suggest that augmenting FNDF content in the PTMR can reshape ruminal fermentation towards acetate production and promote rumination to enhance ruminal pH, thereby alleviating the risk of ruminal acidosis. When the RDS content in the PTMR was 15.57%, an FNDF content of 12.48% was optimal for maintaining stable ruminal function in sheep, and the recommended ratio of FNDF to RDS was 0.8.
