Table 4.

Mortality distributional assumptions for cattle type and antimicrobial treatment

Antimicrobial	Placement weight (lb)	Season	Meana (%)	SDa (%)
Upper Tier	600	Summer	1.07	0.91
Upper Tier	600	Winter	1.36	1.23
Upper Tier	800	Summer	0.94	0.55
Upper Tier	800	Winter	1.57	0.54
Lower Tier	600	Summer	4.14	3.77
Lower Tier	600	Winter	5.26	5.08
Lower Tier	800	Summer	3.66	2.30
Lower Tier	800	Winter	6.10	2.24
No Metaphylaxis	600	Summer	6.68	6.49
No Metaphylaxis	600	Winter	8.49	8.75
No Metaphylaxis	800	Summer	5.90	3.96
No Metaphylaxis	800	Winter	9.83	3.87

^aTo account for endogenous producer decisions in using specific antimicrobials on specific cattle populations we use the odds ratios from Abell et al. (2017) for the lower tier antimicrobial and the mortality observed in lower tier antimicrobials to solve for the mortality of the control. We then use this control mortality and the odds ratios for the upper tier antimicrobial to obtain the mortality for the upper tier antimicrobial. This allows us to obtain the mortality of different antimicrobials on different cattle populations. A similar producer was used to find the standard deviations. In some cases, due to the absence of sufficient observations of steer pens (i.e., n ≥ 20), a pooled steer and heifer estimate was used.

Source: Proprietary feedlot data and Abell et al. (2017).