Carlson Zac E, McPhillips Levi J, Erickson Galen E, Drewnoski Mary E, MacDonald Jim C
Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
Transl Anim Sci. 2022 Jun 29;6(3):txac090. doi: 10.1093/tas/txac090. eCollection 2022 Jul.
An experiment was conducted to measure production responses of an alternative cow-calf production system integrated into a cropping system without access to perennial forage compared to a traditional cow-calf system utilizing perennial forage. Multiparous, cross-bred beef cows ( = 160; average age = 6.2 ± 2.8 yr) were utilized in a randomized complete block experimental design and unstructured treatment design. Upon initiation, cows were blocked by age and stratified by source, assigned randomly to one of two production systems, each with four replicates ( = 20 cows/replicate). Once allotted to their treatment groups, cows remained in their experimental units for the duration of the experiment. Treatments were: 1) a traditional system consisting of April to May calving with smooth bromegrass pasture and grazed corn residue as forage resources (TRAD); 2) an alternative system consisting of July to August calving utilizing partial-drylot feeding, summer-planted oats, and corn residue grazing (ALT). There were no differences ( 0.27) in calving rates (91.8 vs. 86.7 ± 2.92%), pregnancy rates (89.3 vs. 89.9 ± 2.66%), and weaning rates (87.2 vs. 82.3 ± 3.29%) for TRAD vs. ALT, respectively. However, there was an increase ( = 0.04) in the rate of twin offspring in ALT (2.9 vs. 9.4 ± 2.36% for TRAD vs. ALT, respectively). One calf from the set of twins was selected randomly at birth to be removed from the experiment, so the production data are only from single calves. There was no difference ( = 0.47) in calf body weight at birth (40 vs. 39 ± 0.7 kg for TRAD vs. ALT, respectively). At weaning, calves in the ALT system were lighter ( < 0.01) at the same day of age (184 vs. 229 ± 5.5 kg) compared to TRAD calves. Cows from the ALT system had fewer ( < 0.01) kg weaned per cow exposed to bull (150 vs. 199 ± 7.2 kg) compared to TRAD cows. Apart from the twinning rate, no differences in reproductive performance were observed among systems. However, reduced weaning weights and kilogram of weaned calf per cow exposed may negatively impact revenue to the cow-calf enterprise of the ALT system.
进行了一项实验，以测量与利用多年生牧草的传统母牛-犊牛生产系统相比，整合到无多年生牧草的种植系统中的替代母牛-犊牛生产系统的生产反应。采用多胎杂交肉牛（= 160头；平均年龄 = 6.2 ± 2.8岁）进行随机完全区组实验设计和非结构化处理设计。实验开始时，母牛按年龄进行分组，并按来源进行分层，随机分配到两个生产系统之一，每个系统有四个重复（= 20头母牛/重复）。一旦分配到各自的处理组，母牛在整个实验期间都留在其实验单元中。处理方式为：1）传统系统，4月至5月产犊，以草地早熟禾牧场和放牧后的玉米秸秆作为饲料资源（TRAD）；2）替代系统，7月至8月产犊，采用部分舍饲、夏季种植燕麦和玉米秸秆放牧（ALT）。TRAD和ALT的产犊率（分别为91.8%和86.7 ± 2.92%）、妊娠率（分别为89.3%和89.9 ± 2.66%）和断奶率（分别为87.2%和82.3 ± 3.29%）没有差异（P>0.27）。然而，ALT的双胎后代率有所增加（P = 0.04）（TRAD和ALT分别为2.9%和9.4 ± 2.36%）。出生时从双胞胎中随机选择一头小牛从实验中移除，因此生产数据仅来自单胎小牛。出生时小牛体重没有差异（P = 0.47）（TRAD和ALT分别为40 kg和39 ± 0.7 kg）。断奶时，ALT系统中的小牛在相同日龄时（184 kg和229 ± 5.5 kg）比TRAD系统中的小牛体重更轻（P<0.01）。与TRAD系统的母牛相比，ALT系统的母牛每头暴露于公牛的母牛断奶的小牛体重更轻（P<0.01）（分别为150 kg和199 ± 7.2 kg）。除双胎率外，各系统间未观察到繁殖性能的差异。然而，断奶体重降低以及每头暴露母牛的断奶小牛体重减轻可能会对ALT系统的母牛-犊牛企业的收益产生负面影响。
