Wiegand Jacob B, Cooke Reinaldo F, Brandão Alice P, Schubach Kelsey M, Colombo Eduardo A, Daigle Courtney L, Duff Glenn C, Gouvêa Vinicius N
Department of Animal Science - Texas A&M University, College Station, TX.
Prairie Research Unit - Mississippi State University, Prairie, MS.
Transl Anim Sci. 2020 Nov 10;4(4):txaa204. doi: 10.1093/tas/txaa204. eCollection 2020 Oct.
This experiment compared physiological, health, and performance responses of beef heifers assigned to different commingling schemes (one, two, or four sources per pen) during a 56-d feedlot receiving period. Ninety-six recently weaned Angus-influenced heifers were obtained from an auction facility. Heifers originated from four cow-calf ranches, and were reared in the same herd within each ranch since birth. Heifers were loaded into two livestock trailers at the auction yard (two sources per trailer; d -2), arranged in two sections of each trailer according to source, and transported for 10 h to stimulate the stress of a long-haul. Heifers were not mixed with cohorts from other sources prior to and at the auction yard. Upon arrival (d -2), shrunk body weight (BW) was recorded and heifers were maintained in four paddocks by source with ad libitum access to a complete starter feed and water for 36 h. On d 0, heifers were ranked by source and shrunk BW and allocated to 1 of 24 drylot pens (four heifers per pen) containing: 1) heifers from a single source (1SRC, = 8), 2) heifers from two sources (2SRC, = 8), or 3) heifers from four sources (4SRC, = 8). From d 0 to d 55, heifers had free-choice access to the complete starter feed and water. Heifers were assessed daily for symptoms of bovine respiratory disease (BRD), and feed intake was recorded from each pen daily. Blood samples were collected on d 0, d 6, d 13, d 27, d 41, and d 55, and shrunk BW (after 16 h of water and feed withdrawal) was recorded on d 56 for average daily gain (ADG). No treatment differences were noted ( ≥ 0.56) for heifer ADG (mean ± SE = 0.853 ± 0.043 kg/d), final shrunk BW, feed intake, and feed efficiency. No treatment differences were noted ( ≥ 0.27) for plasma concentrations of cortisol and haptoglobin, and serum concentrations of antibodies against BRD viruses and . No treatment differences were noted ( ≥ 0.17) for incidence of BRD (mean ± SE = 59.3 ± 5.0%) or mortality. The proportion of heifers diagnosed with BRD that required three antimicrobial treatments to regain health increased linearly ( = 0.03) according to the number of sources (0.0, 12.3, and 20.8% of 1SRC, 2SRC, and 4SRC heifers, respectively; SEM = 7.0). Hence, commingling heifers from different sources did not impact performance, physiological responses, and BRD incidence during a 56-d receiving period, although recurrence of BRD after the second antimicrobial treatment increased according to commingling level.
本实验比较了在56天的饲养场接收期内，分配到不同混群方案（每栏1个、2个或4个来源）的小母牛的生理、健康和生产性能反应。从一个拍卖场获得了96头最近断奶的受安格斯影响的小母牛。这些小母牛来自四个母牛-犊牛牧场，自出生以来一直在每个牧场的同一牛群中饲养。小母牛在拍卖场被装入两辆牲畜拖车（每辆拖车2个来源；第-2天），根据来源在每辆拖车的两个区域进行安排，并运输10小时以模拟长途运输的应激。在拍卖场之前和期间，小母牛没有与其他来源的同群牛混合。到达时（第-2天），记录收缩体重（BW），并按来源将小母牛饲养在四个围场中，自由采食完全开食料和饮水36小时。在第0天，按来源对小母牛进行排名并记录收缩体重，然后将其分配到24个干栏中的1个（每栏4头小母牛），其中包含：1）来自单一来源的小母牛（1SRC，n = 8），2）来自两个来源的小母牛（2SRC，n = 8），或3）来自四个来源的小母牛（4SRC，n = 8）。从第0天到第55天
