Thompson Logan R, Beck Matthew R, Buskirk Daniel D, Rowntree Jason E, McKendree Melissa G S
Department of Animal Science, Michigan State University, East Lansing, MI.
Faculty of Agriculture and Life Sciences, Lincoln University, Canterbury, New Zealand.
Transl Anim Sci. 2020 Sep 10;4(3):txaa166. doi: 10.1093/tas/txaa166. eCollection 2020 Jul.
In recent decades, beef cattle producers have selected cattle for biological traits (i.e., improved growth) to maximize revenue, leading to an increase in average cow body size. However, matching cow size to the production environment would allow producers to maximize productivity and economic returns per unit of land. This may help meet the goals of sustainable intensification, but environmental complexity and varying cow-calf production systems dictates a regional approach. The objective of this experiment was to examine the biological efficiency and economic returns of a Northern Michigan cow-calf system. We hypothesized that biological efficiency and economic returns would decrease with increasing cow body size. Data were collected from a Red Angus cow herd located at the Lake City AgBio Research Center in Lake City, MI from 2011 to 2018 on cow age, weight, and body condition score at weaning, and subsequent 205 d adjusted calf weaning weight (WW), sex, and yearling weight. Biological efficiency was defined as WW as a percentage of cow body weight (DBW). Enterprise budgeting techniques were used to calculate expected net returns from 2011 to 2018 after classifying cows into 11 BW tiers at 22.67 kg intervals beginning at 430.83 kg. Forward-looking net present value (NPV) was calculated using the same tier system, for a 10-yr production cycle with the baseline being a 200 d grazing season. Weaning weight increased with increasing DBW ( < 0.01), but the percentage of cow body weight weaned was reduced by -38.58 × Ln(DBW) ( < 0.01). This led to cows weaning 26.38 kg/ha more with every 100 kg drop in DBW. Expected net returns from 2011 to 2018 did not differ by DBW tier on a per cow basis but did on a per ha basis with a decrease in $10.27/ha with each increase in DBW tier ( < 0.01). Net present value was maximized in the baseline scenario at 453.51 kg DBW and decreased in value as DBW increased. These results suggest that for a Northern Midwestern cow-calf herd, comparatively lighter cows provide a higher economic value on a land basis.
近几十年来，肉牛养殖户为了实现收益最大化，选择具有生物学特性（即生长性能更好）的牛，这导致母牛平均体型增大。然而，使母牛体型与生产环境相匹配，能够让养殖户实现单位土地生产力和经济回报的最大化。这可能有助于实现可持续集约化的目标，但环境复杂性和不同的母牛-犊牛生产系统决定了需要采取因地制宜的方法。本试验的目的是研究密歇根州北部一个母牛-犊牛养殖系统的生物学效率和经济回报。我们假设生物学效率和经济回报会随着母牛体型的增大而降低。2011年至2018年期间，从密歇根州莱克城的莱克城农业生物技术研究中心的一个红安格斯牛群收集了数据，内容包括母牛年龄、体重、断奶时的体况评分，以及随后的205天调整后犊牛断奶体重（WW）、性别和周岁体重。生物学效率定义为WW占母牛体重（DBW）的百分比。在将母牛按照从430.83千克开始、以22.67千克为间隔划分为11个体重等级后，采用企业预算技术计算2011年至2018年的预期净回报。使用相同的等级系统计算前瞻性净现值（NPV）（10年生产周期，以200天放牧季节为基线）。断奶体重随DBW增加而增加（<0.01），但断奶时占母牛体重的百分比下降了-38.58×Ln(DBW)（<0.01）。这导致DBW每下降100千克，母牛每公顷断奶体重增加26.38千克。2011年至2018年的预期净回报按每头母牛计算，在不同DBW等级间没有差异，但按每公顷计算则有差异，DBW等级每增加一级，每公顷净回报减少10.27美元（<0.01）。在基线情景下，净现值在DBW为453.51千克时最大化，且随着DBW增加而降低。这些结果表明，对于美国中西部北部的一个母牛-犊牛群来说，相对较轻的母牛在单位土地上具有更高的经济价值。
