Khan Ghulam Q, Prestløkken Egil, Lund Peter, Hellwing Anne L F, Larsen Mogens
Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences (NMBU), Ås, Norway.
Department of Animal Science, Aarhus University, Tjele, Denmark.
J Anim Physiol Anim Nutr (Berl). 2023 Jul;107(4):981-994. doi: 10.1111/jpn.13787. Epub 2022 Nov 10.
Dynamics of starch digestion in dairy cows fed extruded pellets differing in physical functional properties were investigated by measuring starch digestibility, post-prandial rumen fermentation patterns, and post-prandial duodenal starch appearance. Additionally, starch digestion effects on neutral detergent fiber (NDF) digestibility and methane (CH ) emission were studied. Pure barley was extruded to produce three treatments having pellets of either low-density (LD), medium-density (MD) or high-density (HD). The experiment was conducted in a 3 × 3 Latin square design using three lactating Danish Holstein cows fitted with ruminal, duodenal and ileal cannulas. After the allocation of experimental concentrate directly into the rumen through the rumen cannula, cows were fed a basal diet low in starch. Eight samples were collected on equal time intervals (9 h) from duodenal digesta, ileal digesta and feces (grab sample) to determine digestibility. For post-prandial rumen fermentation patterns, four sample sets of rumen dorsal, medial and ventral fluid were taken from each cow, whereas for post-prandial duodenal starch appearance, 14 samples of duodenal chyme were obtained from each cow relative to morning feeding of experimental concentrate at 07:00 h. Ruminal, small intestinal, hindgut and total tract digestibility of starch did not differ among treatments. Similarly, NDF digestibility and CH emission also remained unaffected by treatments. However, compared with the LD and MD treatments, the HD treatment showed higher acetate: propionate ratio at all positions in the rumen and a higher post-prandial duodenal starch appearance. This indicates lower ruminal starch degradation (RSD) and higher starch flow into the small intestine for HD treatment. In conclusion, the current study indicates that pellets' physical properties can manipulate RSD, where pellets with high density and fluid stability can partly shift starch digestion from the rumen to the small intestine. Indeed, further investigations are needed.
通过测量淀粉消化率、餐后瘤胃发酵模式和餐后十二指肠淀粉出现情况，研究了饲喂具有不同物理功能特性的挤压颗粒饲料的奶牛淀粉消化动态。此外，还研究了淀粉消化对中性洗涤纤维（NDF）消化率和甲烷（CH）排放的影响。将纯大麦进行挤压，制成三种处理的颗粒饲料，分别为低密度（LD）、中密度（MD）或高密度（HD）。实验采用3×3拉丁方设计，使用三头装有瘤胃、十二指肠和回肠瘘管的丹麦泌乳荷斯坦奶牛。通过瘤胃瘘管将实验精料直接放入瘤胃后，给奶牛饲喂低淀粉基础日粮。在相同时间间隔（9小时）从十二指肠食糜、回肠食糜和粪便（随机样本）中采集八个样本，以测定消化率。对于餐后瘤胃发酵模式，从每头奶牛采集瘤胃背侧、中间和腹侧液体的四个样本组，而对于餐后十二指肠淀粉出现情况，相对于07:00时实验精料的早晨饲喂，从每头奶牛获取14个十二指肠食糜样本。各处理间淀粉的瘤胃、小肠、后肠和全消化道消化率无差异。同样，NDF消化率和CH排放也不受处理影响。然而，与LD和MD处理相比，HD处理在瘤胃所有位置的乙酸：丙酸比值更高，餐后十二指肠淀粉出现量更高。这表明HD处理的瘤胃淀粉降解（RSD）较低，进入小肠的淀粉流量较高。总之，本研究表明颗粒饲料的物理性质可控制RSD，高密度和流体稳定性高的颗粒饲料可使淀粉消化部分从瘤胃转移至小肠。确实，还需要进一步研究。
