Department for Farm Animals and Veterinary Public Health, Institute of Animal Nutrition and Functional Plant Compounds, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria.
Department for Farm Animals and Veterinary Public Health, Institute of Animal Nutrition and Functional Plant Compounds, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria.
J Dairy Sci. 2021 Jul;104(7):7781-7793. doi: 10.3168/jds.2020-19998. Epub 2021 Apr 15.
We reported recently that adding bakery by-products (BP) to the diets of dairy cows up to 30% improved performance and rumen pH, but caused major shifts in the nutrient profile and availability, likely modifying nutrient degradation patterns throughout the gastrointestinal tract. The aim of this study was to investigate the effects of the gradual replacement of cereals by BP on the apparent total-tract digestibility (ATTD), the fermentation patterns, and the microbial community in feces of dairy cows. Twenty-four mid-lactating Simmental cows (149 ± 22.3 days in milk, 756 ± 89.6 kg of initial body weight) were fed a total mixed ration ad libitum (fresh feed was offered twice per day) containing a 50:50 ratio of forage to concentrate (dry matter basis) throughout the experiment. The trial lasted 5 wk, whereby the first week was used for baseline measurements, in which all cows received the same diet, without BP. Cows were then randomly allocated into 3 groups differing in the BP content of diets (0% BP, 15% BP, and 30% BP on a DM basis) and fed for 4 wk. Fecal samples were taken for analysis of pH, volatile fatty acids (VFA), and 16S rRNA gene sequencing. The inclusion of BP resulted in an increase of ether extract and sugars, and a reduction of starch and neutral detergent fiber in the diet. Feeding BP linearly increased the ATTD of almost all nutrients resulting in up to 2 kg more digestible organic matter intake (DOMI). Increasing BP level up to 30% increased fecal total VFA concentration and decreased the pH. The proportion of butyrate in feces increased linearly, but the proportion of all other VFA was not affected by BP-feeding. The richness and diversity indices of the fecal microbiota linearly declined by the inclusion of BP. The cellulolytic phyla Fibrobacteres decreased, whereas amylolytic phyla, such as Proteobacteria, increased. Overall, results showed that feeding BP linearly increased ATTD and DOMI, but impaired fecal microbial diversity and pH. In the interest of the optimization of BP inclusion in the dairy cows' feeding, a dietary level between 15 to 30% of BP might be a better compromise than 30% in terms of an enhanced DOMI and performance with still lowered risk of hindgut dysbiosis, but this will require further investigations.
我们最近报道称，在奶牛日粮中添加 30%的面包店副产品（BP）可以提高奶牛的生产性能和瘤胃 pH 值，但会导致营养成分和可利用性的重大变化，可能会改变整个胃肠道的营养降解模式。本研究旨在探讨逐渐用 BP 替代谷物对奶牛的全肠道表观消化率（ATTD）、发酵模式和粪便微生物群落的影响。24 头泌乳中期西门塔尔奶牛（泌乳天数 149±22.3 天，初始体重 756±89.6kg）在整个试验过程中自由采食含 50:50 比例的粗饲料和精料的全混合日粮（每天提供两次新鲜饲料）。试验持续 5 周，第 1 周用于基线测量，所有奶牛均接受相同的日粮，不含 BP。然后将奶牛随机分为 3 组，日粮中 BP 的含量分别为 0%、15%和 30%（以干物质基础计），并分别饲喂 4 周。采集粪便样本进行 pH 值、挥发性脂肪酸（VFA）和 16S rRNA 基因测序分析。BP 的添加增加了乙醚提取物和糖的含量，降低了日粮中的淀粉和中性洗涤纤维。BP 的添加线性增加了几乎所有养分的 ATTD，导致可消化有机物采食量（DOMI）增加了 2kg 以上。BP 水平增加至 30%时，粪便总 VFA 浓度增加，pH 值降低。粪便中丁酸的比例呈线性增加，但所有其他 VFA 的比例不受 BP 喂养的影响。BP 喂养线性降低粪便微生物区系的丰富度和多样性指数。纤维素分解菌厚壁菌门减少，而淀粉分解菌如变形菌门增加。总的来说，结果表明，BP 的添加线性增加了 ATTD 和 DOMI，但损害了粪便微生物的多样性和 pH 值。为了优化 BP 在奶牛日粮中的添加，在提高 DOMI 和生产性能的同时，BP 的添加水平在 15%至 30%之间可能比 30%更具优势，因为这样可以降低后肠菌群失调的风险，但这还需要进一步研究。
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