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Optimum roughage proportion in barley-based feedlot cattle diets: Growth performance, feeding behavior, and carcass traits.
Journal of Animal Science ( IF 3.3 ) Pub Date : 2020-09-16 , DOI: 10.1093/jas/skaa299
Karen M Koenig 1 , Gwinyai E Chibisa 1, 2 , Gregory B Penner 3 , Karen A Beauchemin 1
Affiliation  

High grain diets are fed to finishing beef cattle to maximize animal performance in a cost-effective manner. However, a small amount of roughage is incorporated in finishing diets to help prevent ruminal acidosis, although few studies have examined optimum roughage inclusion level in barley-based diets. The objective of the study was to evaluate the effects of roughage proportion in barley-based finishing diets on growth performance, feeding behavior and carcass traits of feedlot cattle. Crossbred beef steers (n = 160; mean body weight ± SD, 349.7 ± 21.4 kg) were allocated to 20 pens that were assigned randomly to 4 dietary treatments (5 pens of 8 steers per treatment). The treatment diets contained barley silage at 0, 4, 8, and 12% of dietary dry matter (DM). The remainder of the diets (DM basis) consisted of 80, 76, 72, and 68% barley grain, respectively, 15% corn dried distiller’s grains, 5% mineral and vitamin supplement, and 32 mg monensin/kg diet DM. The diets were fed as total mixed rations for ad libitum intake (minimum of 5% refusal) once per day. Cattle were weighed on 2 consecutive days at the start and end of the experiment and on 1 d every 3 wk throughout the experiment (124 days). Two pens for each treatment group were equipped with an electronic feeding system (GrowSafe Systems Ltd., Calgary, Alberta) to monitor feed intake and feeding behavior of individual cattle. The data for dry matter intake (DMI), average daily gain (ADG), gain:feed (G:F) ratio, and carcass traits were analyzed as a completely randomized design with fixed effect of barley silage proportion and pen replicate as experimental unit. Feeding behavior data were analyzed similarly, but with animal as experimental unit. Averaged over the study, DMI increased linearly (11.1, 11.3, 11.7, 11.8 kg/d; P = 0.001) as barley silage proportion increased from 0, 4, 8, and 12% of DM, but ADG was not affected (carcass-adjusted,1.90, 1.85, 1.87, 1.89 kg/d; P ≥ 0.30). Consequently, G:F ratio decreased linearly (carcass-adjusted, 168.9, 163.8, 158.5, 160.6 g/kg DMI; P = 0.023). When averaged over the study, proportion of barley silage in the diet had no linear or quadratic effects (P > 0.10) on meal frequency, duration of meals, intermeal duration, or meal size, but eating rate decreased linearly with increasing silage proportion (P = 0.008). There was no diet effect on liver abscesses (P ≥ 0.92), and effects on carcass characteristics were minor or non-existent. We conclude that increasing the proportion of barley silage in a feedlot finishing diet at the expense of barley grain to minimize the incidence of ruminal acidosis may decrease feed conversion efficiency.

中文翻译:

以大麦为基础的饲养场牛日粮中的最佳粗饲料比例:生长性能、摄食行为和胴体性状。

将高谷物日粮喂给育肥肉牛,以经济有效的方式最大限度地提高动物性能。然而,在精加工日粮中加入少量粗饲料有助于预防瘤胃酸中毒,尽管很少有研究检查过以大麦为基础的日粮中的最佳粗饲料添加水平。本研究的目的是评估以大麦为基础的育肥日粮中粗饲料比例对饲养场牛生长性能、摄食行为和胴体性状的影响。杂交阉牛 (n = 160; 平均体重 ± SD, 349.7 ± 21.4 kg) 被分配到 20 个围栏中,这些围栏被随机分配到 4 个日粮处理中(每个处理 5 个 8 头牛的围栏)。处理日粮含有 0、4、8 和 12% 的日粮干物质 (DM) 的大麦青贮饲料。其余的日粮(以干物质为基础)由 80%、76%、72% 和 68% 的大麦粒组成,分别为 15% 的玉米干酒糟、5% 的矿物质和维生素补充剂以及 32 mg 莫能菌素/kg 日粮 DM。每天一次将饮食作为随意摄入的总混合口粮(至少 5% 拒绝)喂食。牛在实验开始和结束时连续 2 天称重,在整个实验过程中每 3 周称重 1 天(124 天)。每个处理组的两个围栏都配备了电子饲喂系统(GrowSafe Systems Ltd., Calgary, Alberta),以监测个体牛的采食量和采食行为。干物质采食量 (DMI)、平均日增重 (ADG)、增重:饲料 (​​G:F) 比和胴体性状的数据被分析为完全随机设计,以大麦青贮比例和围栏重复作为实验单位的固定效应. 类似地分析摄食行为数据,但以动物为实验单位。在研究中平均,DMI 线性增加(11.1、11.3、11.7、11.8 kg/d;P = 0.001)随着大麦青贮比例从 DM 的 0、4、8 和 12% 增加,但 ADG 不受影响(胴体调整,1.90、1.85、1.87、1.89 kg/d;P ≥ 0.30)。因此,G:F 比率线性下降(经胴体调整后为 168.9、163.8、158.5、160.6 g/kg DMI;P = 0.023)。当在整个研究中进行平均时,日粮中大麦青贮饲料的比例对进餐频率、进餐时间、餐间持续时间或进餐量没有线性或二次影响(P > 0.10),但进餐率随着青贮饲料比例的增加呈线性下降(P = 0.008)。饮食对肝脓肿无影响(P≥ 0.92),对胴体特性的影响很小或不存在。我们得出结论,以牺牲大麦谷物为代价增加饲养场育肥日粮中大麦青贮饲料的比例以尽量减少瘤胃酸中毒的发生率可能会降低饲料转化效率。
更新日期:2020-09-21
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