Cooper S D, Kyriazakis I, Nolan J V
Genetics and Behavioural Sciences Department, Scottish Agricultural College Edinburgh.
Br J Nutr. 1995 Jul;74(1):39-54. doi: 10.1079/bjn19950105.
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.(ABSTRACT TRUNCATED AT 400 WORDS)
通过两个实验研究了提供多种选择时饲料能量密度（ED）对绵羊饮食选择的影响，以及瘤胃环境与从不同能量密度饲料中选择的饮食之间的关系。在第一个实验中，配制了两种饲料L和H以及它们的混合物M（重量比3:1）。所有饲料的可消化粗蛋白与可消化能量（ME）的计算比值相似，但能量密度不同（L、M和H的ME分别为7.4、8.1和10.1 MJ/kg新鲜饲料）。这些饲料可自由采食，单独或成对提供给生长中的绵羊（L/M、L/H和M/H；每个处理6只）。尽管采食饲料H的绵羊体重增加速度高于采食饲料L或M的绵羊，且每日采食量较低，但选择饲料的绵羊并未只采食饲料H。相反，它们选择了提供的两种饲料的混合物，使得在L/H和M/H选择中每千克新鲜饲料消耗的H总量相似。选择L/H和M/H的绵羊体重增加速度与仅采食饲料H的绵羊无异。在第二个实验中，将L/H选择提供给装有瘤胃瘘管的绵羊（10月龄，平均体重57.5 kg），采用8×8拉丁方设计，每期7天。处理方式为在每个周期的第1 - 4天，在4小时内通过瘤胃瘘管向瘤胃注入（总体积1升）酸（HCl；酸1为400、酸2为300、酸3为200 mmol/l）、碱（NaOH；碱1为316、碱2为212、碱3为109 mmol/l）和对照（NaCl；对照1为315、对照2为209 mmol/l）。注入液的渗透压（mOs/kg）分别为795（酸1）、585（酸2、碱1和对照1）、390（酸3、碱2和对照2）和200（碱3）。根据注入液的渗透压，注入处理对绵羊的饮食选择有显著影响（P < 0.05），但根据瘤胃pH值则无显著影响。在注入过程中，随着处理渗透压的增加，饲料H的采食量趋于下降，而饲料L的采食量保持不变。对饮食选择和采食量的影响持续时间较短，且无残留效应。（摘要截断于400字）
