Department of Animal Science, AU Foulum, Aarhus University, DK 8830 Tjele, Denmark.
Department of Animal Science, AU Foulum, Aarhus University, DK 8830 Tjele, Denmark.
J Dairy Sci. 2022 Nov;105(11):8806-8823. doi: 10.3168/jds.2021-21653. Epub 2022 Aug 31.
The objective of this study was to investigate the effects of heat treatment (toasting) and particle size alterations (grinding; rolling) on nutrient utilization, ruminal fermentation, and supply of metabolizable protein (MP), and to study the interaction between processing conditions of fava beans and forage type. Six Danish Holstein dairy cows fitted with ruminal, duodenal, and ileal cannulas were used in a 6 × 4 incomplete Latin square design with 4 periods of 21-d duration. Cows were fed ad libitum with 6 experimental diets: diets high in either grass-clover silage or corn silage were combined with ground untoasted, ground toasted, or rolled untoasted fava beans. Samples of ruminal fluid, digesta from duodenum and ileum, and feces were collected, and nutrient digestibility was estimated using CrO and TiO as flow markers. Diets high in corn silage resulted in higher ruminal pH and higher proportion of propionate in ruminal volatile fatty acids compared with diets high in grass-clover silage. Diets high in corn silage resulted in higher apparent total-tract digestibility of crude protein and starch but lower apparent ruminal and total-tract digestibility of neutral detergent fiber compared with diets high in grass-clover silage. Rolling of fava beans decreased the in situ small intestinal disappearance of rumen-undegradable protein corrected for particle losses. Compared with grinding, rolling of fava beans reduced apparent ruminal digestibility of starch, true ruminal digestibility of organic matter, crude protein, and AA, and small intestinal digestibility of AA and starch. Grinding of fava beans increased apparent ruminal digestibility of neutral detergent fiber and reduced the proportion of propionate in ruminal volatile fatty acids compared with rolling of fava beans. In addition, rolling of fava beans had no effect on MP supply. Toasting of fava beans had no effect on in vivo nutrient digestibility except for an interaction with forage source on apparent ruminal dry matter and organic matter digestibility. Toasting of fava beans did not affect small intestinal digestion of individual and total AA, and therefore failed to increase MP supply. In conclusion, neither replacing grass-clover silage with corn silage, nor toasting nor rolling of fava beans had an effect on supply of MP.
本研究旨在探究热处理（烘烤）和颗粒大小改变（粉碎；碾压）对养分利用、瘤胃发酵和可代谢蛋白（MP）供应的影响，并研究烘烤处理条件和饲草料类型之间的相互作用。选用 6 头安装有瘤胃、十二指肠和回肠瘘管的丹麦荷斯坦奶牛，采用 6×4 不完全拉丁方设计，每个周期 21d，共 4 个周期。奶牛自由采食 6 种试验日粮：高青贮玉米或高青贮三叶草日粮分别与粉碎未烘烤、粉碎烘烤和碾压未烘烤的蚕豆组合。采集瘤胃液、十二指肠和回肠食糜及粪便样品，使用 CrO 和 TiO 作为示踪剂估算养分消化率。与高青贮三叶草日粮相比，高青贮玉米日粮导致瘤胃 pH 升高，瘤胃挥发性脂肪酸丙酸比例增加。高青贮玉米日粮导致粗蛋白和淀粉的表观全肠道消化率升高，而中性洗涤纤维的表观瘤胃和全肠道消化率降低。与粉碎相比，碾压降低了校正颗粒损失后的瘤胃未降解蛋白的原位小肠消失率。与碾压相比，粉碎降低了蚕豆的表观瘤胃淀粉消化率、真瘤胃有机物消化率、粗蛋白和氨基酸、以及小肠氨基酸和淀粉消化率。与碾压相比，粉碎增加了中性洗涤纤维的表观瘤胃消化率，降低了瘤胃挥发性脂肪酸中丙酸的比例。此外，粉碎对 MP 供应没有影响。除了与饲草料来源的互作，烘烤对体内养分消化率没有影响，仅影响表观瘤胃干物质和有机物消化率。烘烤没有影响单个和总氨基酸的小肠消化，因此未能增加 MP 供应。总之，无论是用青贮玉米替代青贮三叶草，还是烘烤或碾压蚕豆，都不会影响 MP 的供应。
