Growth Performance, Rumen Fermentation and Inflammatory Response on Holstein Growing Cattle Treated with Low and High Non-Fibrous Carbohydrate to Neutral Detergent Fiber Ratio Pelleted Total Mixed Ration

SIMPLE SUMMARY: Total mixed rations (TMR) have become the usual feeding method for cattle, since being brought into ruminant feeding systems. Though there are numerous benefits of TMR, it also possesses some drawbacks, especially feed sorting. This has resulted in the recent tendency to provide fully pelleted TMR to sheep and goats in some regions of the world. However, the application of pelleted TMR treated with different non-fibrous carbohydrate (NFC) to neutral detergent fiber (NDF) ratio on Holstein growing cattle was unknown. This research was carried out to investigate the influences of low and high NFC to NDF ratio pelleted TMR on growth performance, rumen fermentation and inflammatory response in Holstein growing cattle. The results demonstrated that low NFC/NDF (1.07) pelleted TMR can improve the growth performance, reduce feed costs and elevate the digestibility of DM, NDF as well as ADF of Holstein growing cattle. However, high NFC/NDF (1.71) pelleted TMR has adverse effects on rumen fermentation and inflammatory response compared with low NFC/NDF (1.07). Under the condition of this experiment, low NFC/NDF (1.07) pelleted TMR is recommended when applied for Holstein growing cattle fattening. ABSTRACT: Twenty-four healthy castrated male Holstein growing cattle, with similar body weight (301 ± 11.5 kg), were enrolled in this study and randomly allocated into two groups (12/pen). Holstein growing cattle in the LPT (low NFC/NDF pelleted TMR) group were fed basal pelleted TMR with a low NFC/NDF ratio (NFC/NDF = 1.07), while the HPT (high NFC/NDF pelleted TMR) group were fed with a high NFC/NDF ratio diet (NFC/NDF = 1.71). The results showed that: (1) Body measurements were found to be increased for the LPT group (p < 0.05); compared with the HPT group, feed intake to gain ratio and feed cost in the LPT group were decreased by 12.24% and 15.35%, respectively (p < 0.01). Compared with the HPT group, the LPT group tended to increase chest girth. (2) Digestibility of DM and NDF in the LPT group was higher (p < 0.05) than in the HPT group, being increased by 3.41% and 4.26%, respectively, and increased digestibility of ADF in the LPT group was significant (p < 0.01). (3) The daily feed consumption of NDF in the LPT group was higher than that in the HPT group and the daily rumination time and chewing time in the LPT group were longer than that in the HPT group (p < 0.05). (4) Compared with the LPT group, the parameter of pH, microbial protein and acetate: propionate (p < 0.05) in the HPT group were decreased by 8.57%, 12.46% and 23.71%, respectively. In contrast, the concentration of total volatile fatty acids, acetate and propionate were higher (p < 0.05) in the HPT group, and increased by 13.49%, 19.59% and 52.70%, respectively. (5) Compared with the LPT group, rumen fluid in the HPT group diet up-regulated the mRNA expression levels of BRECs pro-inflammatory factor IL-1β and TNF-α (p < 0.05), and meanwhile, up-regulated the mRNA expression levels of BRECs pro-inflammatory factor IL-6 (p < 0.01); compared with the LPT group, rumen fluid in the HPT group diet up-regulated the mRNA expression levels of CCL28 and CCL20 (p < 0.05) chemokines in CCL types of BRECs; in addition, compared with the LPT group, rumen fluid in the HPT group up-regulated the mRNA expression levels of CXCL2, CXCL3, CXCL9 and CXCL14 chemokines in CXCL types of BRECs (p < 0.01), and the mRNA expression levels of the CXCL5 chemokine tended to be increased (p = 0.06).