Respiratory disease is the primary cause of mortality in the nursery phase.(1) Respiratory disease can also decrease feed intake and increase susceptibility to enteric pathogens.(2) Additionally, as input costs rise, systems need to be as cost competitive as possible in order to maximize throughput. Pulmotil® (tilmicosin phosphate, Elanco, Greenfield, IN, USA) is a macrolide antibiotic approved for use in swine feed for control of respiratory disease associated with Actinobacillus pleuropneumonia and Pasteurella multocida. Since its US approval in 1996, it has shown efficacy in a variety of situations. However, the most common use today in the US is still in the weaned pig.

Materials and Methods

A large production system with a history of clinical viral and bacterial respiratory disease, including Pasteurella multocida, in the nursery was used in this evaluation. Twenty-four wean-to-finish sites were used in this evaluation in a completely randomized design. Treatments were randomly assigned to site and site was used as the experimental unit. Two treatments were used: 1. Standard Program and 2. Pulmotil step-down. Treatments are listed in Table 1. Diets were supplied to each farm by estimating consumption per head for the period (21 day feeding). Treatments began when pigs were weaned and arrived at the site. Both treatments shared the same protocol for remaining feed treatments, water interventions and vaccinations. Data was collected by the production company and analyzed using Proc Mixed (SAS® , Cary NC, USA) on the response variables of growth performance and mortality, standardized for common days. The model included fixed effects of sow source, treatment and the sow source by treatment interaction. No interactions were observed. Significance level was set at 0.05

Table 1. Treatments and Diets

Ration Standard Program Pulmotil
Prestarter carbadox 50 g/ton Pulmotil 363 g/ton
Starter 1 carbadox 50 g/ton Pulmotil 181 g/ton


Main effects of treatment are presented below as LS Means in Table 2. There was not a significant difference in start weight between treatments. The derived benefits of Average Daily Gain (ADG) and market weight were significantly improved due to Pulmotil at weaning. There also tended to be decreased mortality and increased percentage of pigs marketed (those pigs that reached desirable weight in a specific amount of time and sold to primary market) for this system.

Table 2. Effects of nursery treatment on growth performance and mortality traits

Parameter Standard Program Pulmotil Pooled
Sites evaluated, # 14 10   
Total pigs placed, # 30,348 24, 162
Start weight, lbs 11.79 12.00 0.21 0.47
Market weight, lbs 253.8 260.0 1.49 0.01
Average Days 156.6 158.1 1.57 0.51
ADG, lbs/day 1.30 1.37 0.02 0.02
FE, feed: gain 2.60 2.61 0.04 0.80
Mortality, % 12.09 9.43 1.02 0.08
Pigs marketed, %a,b 77.86 81.61 1.89 0.18

a% pigs marketed=(pigs marketed/total pigs placed)*100
bPigs marketed does not include culls, "lights" or pigs moved to opportunity farms


Wean to finish production systems can be challenging to evaluate interventions. Most production systems must rely on on-farm evaluations using data that is already being collected. Using beginning and ending weights that are 24 weeks apart make it difficult to find slight, yet economically important differences in performance parameters and health of pigs. However, this evaluation shows that differences can be found at the end of the finishing period due to nursery treatment


1. USDA NAHMS. Swine 2000 Part I: Reference of swine health and management in the United States, 2000. 2001.

2. Tubbs, R. and Deen, J. Economics of respiratory and enteric diseases. Proc. AASP, 1997.