Shin Dong-Han, Kang Hyun-Min, Seo Seongwon
Division of Animal and Dairy Science, Chungnam National University, Daejeon, Republic of Korea.
PeerJ. 2017 May 9;5:e3329. doi: 10.7717/peerj.3329. eCollection 2017.
The objective of this study was to evaluate the effects of social relationships on the feed intake, eating behavior, and growth, upon exposure to a novel diet, in Hanwoo () heifers during pregnancy. Twenty-four pregnant Hanwoo heifers, averaging 438 ± 27.8 kg in weight, 21 months in age, and 194 ± 8.5 days in pregnancy, were involved in a two-month (eight weeks) experiment. The heifers were randomly assigned to either the single housing group (SG; one individual per pen, = 12), or the paired housing group (PG; two individuals per pen, = 12). All pens were of the same size (5 × 5 m) and provided with one feed bin, which automatically recorded the individual feed intake and eating behavior. As the experiment began, the diet of the heifers was switched from a total mixed ration (TMR; 250 g/kg ryegrass straw and 750 g/kg concentrate mix) to a forage-only diet (mixed hay cubes composed of 500 g/kg alfalfa, 250 g/kg timothy, and 250 g/kg blue grass hay). The heifers were fed ad libitum twice a day. The individual feed intake and eating behavior were recorded daily throughout the experiment, and body weights (BWs) were measured every four weeks before the morning feeding. PG animals visited the feed bin 22% less often than SG. PG, however, stayed 39% longer in the feed bin and consumed 40% more feed per visit, compared with SG. Consequently, PG heifers spent 23% more time in eating and had 16% more daily dry matter intake than SG during the experiment. Average daily gain during the experimental period tended to be greater in PG than in SG. When pregnant Hanwoo heifers encountered a novel diet, social relationships (i.e., presence of a pen-mate) enhanced their time spent eating and feed intake. Social interactions, even with an unfamiliar individual, may be helpful for pregnant Hanwoo heifers cope with a diet challenge compared to solitary situation.
本研究的目的是评估社会关系对妊娠期间韩牛（）小母牛在接触新日粮时的采食量、采食行为和生长的影响。24头妊娠韩牛小母牛参与了一项为期两个月（八周）的试验，其平均体重为438±27.8千克，年龄为21个月，妊娠期为194±8.5天。小母牛被随机分配到单栏饲养组（SG；每栏一头，n = 12）或配对饲养组（PG；每栏两头，n = 12）。所有栏舍大小相同（5×5米），并配备一个饲料槽，该饲料槽可自动记录个体采食量和采食行为。随着试验开始，小母牛的日粮从全混合日粮（TMR；250克/千克黑麦草秸秆和750克/千克精料混合料）转换为仅含粗饲料的日粮（由500克/千克苜蓿、250克/千克梯牧草和250克/千克早熟禾干草组成的混合干草块）。小母牛每天自由采食两次。在整个试验过程中每天记录个体采食量和采食行为，在早晨饲喂前每四周测量一次体重（BW）。与SG相比，PG组动物访问饲料槽的频率低22%。然而，与SG相比，PG组在饲料槽停留的时间长39%，每次访问消耗的饲料多40%。因此，在试验期间，PG组小母牛采食时间多23%，每日干物质摄入量比SG组多16%。试验期内PG组的平均日增重倾向于高于SG组。当妊娠韩牛小母牛遇到新日粮时，社会关系（即栏舍同伴的存在）增加了它们的采食时间和采食量。与单独饲养的情况相比，即使与不熟悉的个体进行社会互动，也可能有助于妊娠韩牛小母牛应对日粮挑战。
