DIET SELECTION IN SHEEP - THE ROLE OF THE RUMEN ENVIRONMENT IN THE SELECTION OF A DIET FROM 2 FEEDS THAT DIFFER IN THEIR ENERGY DENSITY
DIET SELECTION IN SHEEP - THE ROLE OF THE RUMEN ENVIRONMENT IN THE SELECTION OF A DIET FROM 2 FEEDS THAT DIFFER IN THEIR ENERGY DENSITY
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DOI：
10.1079/bjn19950105
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发表时间：
1995-07-01
影响因子：
3.6
通讯作者：
NOLAN, JV
中科院分区：
文献类型：
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作者：
COOPER, SDB;KYRIAZAKIS, I;NOLAN, JV
通过两个实验研究了饲料能量密度（ED）对绵羊日粮选择的影响，以及瘤胃环境与不同 ED 饲料选择日粮之间的关系。在第一个实验中，配制了两种饲料 L 和 H 及其混合物 M（3:1 w/w）。所有饲料均具有相似的计算可代谢蛋白质：代谢能 (ME) 比率，但 ED 不同（L、M 和 H 分别为 7.4、8.1 和 10.1 MJ ME/kg 新鲜饲料）。这些提要是即兴提供的。单独或成对选择（L/M、L/H 和 M/H；每个处理 n6）到生长中的绵羊。尽管 H 饲料的活重 (Lwt) 增加率高于 L 或 M 饲料，并且每日采食率较低，但选择饲料的羊并不只消耗 H 饲料。相反，它们选择了两种饲料的混合物，这样在选择 L/H 和 M/H 时，每公斤新鲜饲料消耗的 H 总量相似。选择 L/H 和 M/H 时绵羊的 Lwt 增益率与仅使用饲料 H 时获得的 Lwt 增益率没有不同。在第二个实验中，选择 L/H 为 8 x 8 拉丁方中的瘘管羊（10 个月大，平均轻重 57.5 公斤），周期为 7 d。治疗是在每个阶段的第1-4天在4小时内向瘤胃（总体积1升）输注酸（HCl；酸1, 400；酸2, 300和酸3, 200 mmol/l）、碱（NaOH；Alk 1, 316；Alk 2, 212和Alk 3, 109 mmol/l）和对照（NaCl；Con 1, 315 和Con 2, 209 mmol/l)。输注液渗透压 (mOs/kg) 为 795（酸 1）、585（酸 2、Alk 1 和 Con 1）、390（酸 3、Alk 2 和 Con 2）和 200（Alk 3）。根据输注液的渗透压，输注处理显着影响绵羊的饮食选择（P < 0.05），但不根据瘤胃 pH 值。在输注过程中，随着处理渗透压的增加，饲料 H 的摄入量趋于下降，而 L 的摄入量保持恒定。对日粮选择和采食量的影响持续时间较短，且无遗留影响。这些结果表明，在两种不同 ED 饲料之间进行选择时，绵羊会选择大量低 ED 饲料；这种饮食选择受到瘤胃环境短期操纵的影响，其方式与维持有效的瘤胃条件一致。
The effect of the energy density (ED) of feeds offered as a choice on the diet selection of sheep, and the relationship between the rumen environment and the diet selected from feeds of different ED were investigated in two experiments. In the first experiment two feeds, L and H, and their mixture M (3:1 w/w) were formulated. All feeds had similar calculated metabolizable protein: metabolizable energy (ME) ratios, but differed in ED (7.4, 8.1 and 10.1 MJ ME/kg fresh feed for L, M and H respectively). The feeds were offered ad lib. either singly or in paired choices (L/M, L/H and M/H; n6 per treatment) to growing sheep. Although the rate of live-weight (Lwt) gain on feed H was higher than on feeds L or M, and the daily rate of feed intake lower, the sheep on feed choices did not consume only feed H. Instead they selected a mixture of both feeds offered, such that the total amount of H consumed per kg fresh feed was similar on choices L/H and M/H. The rate of Lwt gain of sheep on choices L/H and M/H was not different from that achieved on feed H alone. In the second experiment the choice L/H was offered to fistulated sheep (10 months of age, mean Lwt 57.5 kg) in an 8 x 8 Latin square, with 7 d periods. Treatments were infusions into the rumen (total volume 1 litre) over 4 h on days 1-4 of each period of acid (HCl; Acid 1, 400; Acid 2, 300 and Acid 3, 200 mmol/l), alkali (NaOH; Alk 1, 316; Alk 2, 212 and Alk 3, 109 mmol/l) and control (NaCl; Con 1, 315 and Con 2, 209 mmol/l). Infusate osmolalities (mOs/kg) were 795 (Acid 1), 585 (Acid 2, Alk 1 and Con 1), 390 (Acid 3, Alk 2 and Con 2) and 200 (Alk 3). Infusion treatment significantly affected the diet selection of the sheep (P < 0.05) according to the osmolality of infusate, but not according to rumen pH. During infusions intake of feed H tended to decline with increasing treatment osmolality, whereas intake of L remained constant. The effects on diet selection and feed intake were of a short duration with no carry-over effects. These results show that sheep given a choice between two feeds of different ED select a substantial quantity of the low-ED feed; this diet selection is affected by short-term manipulations of their rumen environment, in a manner that is consistent with the maintenance of effective rumen conditions.