Lopes Ana Laura, Santos Flávio A P, Meschiatti Murillo, de Oliveira Mario Olímpio, Fernandes Juliano J R, Drouillard James S, Cappellozza Bruno I
Universidade Federal do Goiás, Escola de Veterinária e Zootecnia, Goiânia, GO, 74690-900, Brazil.
Universidade de São Paulo, Departamento de Zootecnia, Piracicaba, SP 13418-900, Brazil.
Transl Anim Sci. 2021 May 28;5(3):txab091. doi: 10.1093/tas/txab091. eCollection 2021 Jul.
This study evaluated the effects of administration at the beginning of the feedlot period on performance of bulls. On d 0, 383 Nellore bulls (initial shrunk body weight 384 ± 29.2 kg; initial age = 24 ± 2 mo) were assigned to treatments in a randomized complete block design. Treatments consisted of 1) 14 d adaptation diet and transition to a finishing diet (), 2) CONT plus oral administration of 20 mL of Lactipro-NXT () on d 0 of the study (), 3) CONT diet, consisting of 6 d of adaptation diet plus oral administration of 20 mL of Lactipro-NXT on d 0 of the study (), and 4) No adaptation diet and oral administration of 20 mL of Lactipro-NXT on d 0 of the study (). Experimental period lasted 119 d. No treatment effects were observed for any of the performance parameters evaluated herein ( ≥ 0.15). Nonetheless, a treatment × wk interaction was observed for DM, NE, and NE intakes ( < 0.0001). For all these parameters, MEG-0 and MEG-6 had a reduced intake vs. MEG-14 and CONT in the first wk of the study ( ≤ 0.05). For the carcass traits, no effects were observed for HCW ( ≥ 0.24), whereas MEG-6 had a greater REA when compared with MEG-0 and MEG-14 (quadratic effect; = 0.04) and MEG-administered bulls tended to have a greater BFT vs. CONT ( = 0.08). In summary, administration at the beginning of the feedlot period did not improve performance, whereas reducing the length of the adaptation period for 6 d improved REA of finishing bulls.
本研究评估了在育肥期开始时给药对公牛性能的影响。在第0天，383头内洛尔公牛（初始缩体体重384±29.2千克；初始年龄=24±2月龄）被随机分配到各处理组，采用随机完全区组设计。处理组包括：1）14天适应期日粮并过渡到育肥期日粮（），2）对照组（CONT）加在研究第0天口服20毫升Lactipro-NXT（），3）对照组日粮，包括6天适应期日粮加在研究第0天口服20毫升Lactipro-NXT（），4）无适应期日粮并在研究第0天口服20毫升Lactipro-NXT。试验期持续119天。在此评估的任何性能参数均未观察到处理效应（P≥0.15）。然而，观察到干物质（DM）、净能（NE）和净能摄入量存在处理×周的交互作用（P<0.0001）。对于所有这些参数，在研究的第一周，MEG-0和MEG-6的摄入量相对于MEG-14和对照组有所减少（P≤0.05）。对于胴体性状，热胴体重（HCW）未观察到效应（P≥0.24），而与MEG-0和MEG-14相比，MEG-6的肋眼面积（REA）更大（二次效应；P=0.04），并且与对照组相比，接受MEG处理的公牛的背膘厚度（BFT）有增加的趋势（P=0.08）。总之，在育肥期开始时给药并未改善性能，而将适应期缩短6天可提高育肥牛的肋眼面积。
