Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX.
J Anim Sci. 2018 Mar 6;96(2):684-693. doi: 10.1093/jas/sky011.
Effects of live yeast (Saccharomyces cerevisiae) in steam-flaked corn-based diets fed to natural-program beef cattle on growth performance, total tract apparent digestibility, carcass characteristics, and feeding behavior were evaluated in a randomized block design experiment. Steers (n = 144; 341 ± 7.03 kg) were blocked by initial BW and assigned randomly to 1 of the 3 treatments (n = 12 pens per treatment with 4 steers per pen). Treatments included the following: 1) control (CTL; no yeast); 2) low yeast (LY; 1.5 g/animal daily [3 × 1010 CFU]); and 3) high yeast (HY; 3.0 g/animal daily [6 × 1010 CFU]). Technologies such as implants, ionophores, and antibiotics were not used, and the steam-flaked corn-based finishing diets were fed to provide ad libitum access to feed. Yeast was included in a cottonseed meal-based premix as 1% of the dietary DM. Spot fecal samples (twice daily for 5 consecutive days) and diets were composited by pen and analyzed for acid insoluble ash to estimate apparent total tract digestibility of nutrients. Cattle were slaughtered on days 183 (4 blocks) and 204 (8 blocks). Dry matter intake (P ≥ 0.29), ADG (P ≥ 0.17), and G:F (P ≥ 0.33) did not differ among treatments. The percentage of Premium Choice (P < 0.01) carcasses increased linearly with increasing yeast inclusion in the diet. A quadratic response was observed for total tract apparent digestibility, in which steers fed LY had greater digestibility (P < 0.01) of DM by 5.4%, OM by 4.8%, NDF by 15.2%, ADF by 20.2%, CP by 6.2%, and ether extract (EE) by 2.5% compared with steers fed CTL. Feeding behavior was not affected (P = 0.28) by treatments. Live yeast improved digestibility of DM, OM, CP, EE, and fiber, without changing feeding behavior and growth performance of natural-program steers fed steam-flaked corn-based finishing diets.
在一项随机分组设计试验中，评估了在蒸汽压片玉米基础日粮中添加活酵母（酿酒酵母）对自然程序育肥牛生长性能、全肠道表观消化率、胴体特性和采食行为的影响。将 144 头（初始体重 341 ± 7.03kg）公牛按初始体重分组，并随机分配到 3 种处理组（每组 12 个栏，每个栏 4 头公牛）。处理组包括以下三种：1）对照组（CTL；无酵母）；2）低酵母（LY；每天 1.5 克/动物[3×1010CFU]）；3）高酵母（HY；每天 3.0 克/动物[6×1010CFU]）。未使用植入物、离子载体和抗生素等技术，用蒸汽压片玉米基础育肥日粮进行饲养，以自由采食饲料。酵母添加到棉籽粉基础预混料中，占日粮干物质的 1%。每栏每天采集 2 次粪便（连续 5 天）和日粮进行混合，并分析酸不溶灰分以估计养分的全肠道表观消化率。牛于第 183 天（4 个栏）和第 204 天（8 个栏）屠宰。干物质采食量（P≥0.29）、ADG（P≥0.17）和 G:F（P≥0.33）在处理组间无差异。随着日粮中酵母添加量的增加，优质选择（P＜0.01）胴体比例呈线性增加。全肠道表观消化率呈二次响应，LY 组的 DM（P＜0.01）、OM（P＜0.01）、NDF（P＜0.01）、ADF（P＜0.01）、CP（P＜0.01）和 EE（P＜0.01）的消化率分别提高了 5.4%、4.8%、15.2%、20.2%、6.2%和 2.5%，而 CTL 组则无差异。处理组对采食行为无影响（P=0.28）。活酵母提高了 DM、OM、CP、EE 和纤维的消化率，而不改变蒸汽压片玉米基础育肥日粮育肥牛的采食行为和生长性能。
