Previous studies reported that antibiotics in lactating sow diets reduced problems associated with peripartum infections and improved reproductive performance (1-3). In addition, the inclusion of antibiotics in lactation feed may reduce the transmission of bacterial pathogens from sows to piglets, and improve the health of pigs in the nursery (4). This investigation evaluated the efficacy of Tilmicosin (Pulmotil® 18) in lactation feed to control swine respiratory disease associated with Pasteurella multocida in the sow, to reduce transmission of these pathogens to the piglet, and thus improve piglet survivability and subsequent performance in the nursery. The study also assessed the Integra MicroMeter System® for on-farm delivery of medicated feed.

Materials and Methods

The study was conducted on a commercial farrow-to-wean facility, which had a history of producing pigs with respiratory disease, particularly P multocida. As part of a parity-segregation system, the farm housed primarily gilts. Approximately 96 litters were farrowed each week. Four separate farrowing barns had independent feed systems. Two barns were treatment barns (5 repetitions/barn) and two barns served as controls. Treatment was tilmicosin (363 g/ton) in the feed for the 21 day lactation. Tilmicosin was added to the feed using the MicroMeter System. Piglets and sows were not moved between barns.

Detailed records of farrowing house performance were maintained. For each group, approximately 20 healthy piglets with hernias were euthanized at weaning to facilitate post-mortem examinations.   Appropriate samples were submitted to the Minnesota Veterinary Diagnostic Laboratory. Performance of pigs in the nurseries also was recorded. In treatment and control barns, feed samples were collected from three random feed drops per room. Feed samples were assayed to quantify the tilmicosin delivered in the sow feed. Performance data was analyzed with t-tests.


The MicroMeter was inconsistent and delivered 75%-94% of the target quantity of 363 g tilmicosin/ton.   However, productivity was superior in treatment barns than in control barns (Table 1). Improved productivity also was apparent, albeit somewhat less, in the nursery (Table 1). Joint infections, starve-outs and exudative dermatitis were more common in piglets nursing control sows than in piglets from sows consuming feed with tilmicosin. Diagnostic evaluation of piglets indicated that 23.2+8.7% and 8.7+6.7% of the control and treatment piglets, respectively, had pneumonic lesions, which were confirmed with histopathological examination. Pathogens identified in piglets included Mycoplasma hyopneumoniae, Hemophilus parasuis and Streptococcus suis. PRRSV, SIV, and PCV-2 were diagnosed in occasional pigs with additional PCR testing.  

Table 1. Influence of tilmicosin addition to lactation feed (n=2 barns/treatment, 5 replicates/barn). Mean + STD.   




Farrowing House



Pigs Born Alive

972.3 + 164

986 + 126

Pigs Weaned/Litter Weaned

9.0 + 0.3

9.52 + 0.3a

Pigs Weaned/Sow

8.82 + 0.4

9.26 + 0.4a

Pig Wt (kg) at Weaning

5.62 + 0.6

5.75 + 0.3

PW Mortality (%)

18.5 + 2.3

14.5 + 1.7a




Pigs Moved to Finisher

865 + 334

950 + 310b

ADG (kg/day)

0.34 + 0.04

0.36 + 0.03

FE (feed/gain)

1.4 + 0.1

1.43 + 0.1

% Condemns*

0.67 + 0.4

0.58 + 0.4

Mortality (%)

5.1 + 2.5

3.7 + 2.5c

Kg processed/week**

18367+ 5168


* Pigs unsuitable for transfer to the finishing facilities.

**Total weight of pigs transferred from nursery to finisher. 

a,b,cValues in rows differ, P


Under the conditions of this study, the Integra MicroMeter System® failed to consistently deliver the appropriate quantity of tilmicosin. Additional modifications are required for this system to be effective on this sow farm. Despite lower than expected levels of tilmicosin, overall performance of the treatment barns surpassed the control barns. Diagnostic evaluations revealed that tilmicosin reduced the number of piglets with pneumonic lesions. Consequently, it was apparent that greater numbers of pigs survived the nursery phase of production. Evidently, the tilmicosin did not enhance growth; however, the tilmicosin clearly improved the survivability of pigs. The increased survivability augmented the total kilograms processed each week as pigs moved from the nursery to the finishing phase. In conclusion, this study revealed that the addition of tilmicosin to lactation feed improved the productivity of farrowing facilities, and health of pigs in farrowing and nursery facilities. The therapeutic value of the tilmicosin is easily justified, particularly in a herd with health concerns. 


1.        Frolich, A. et al. (1974). Acta. Agric. Scand. 24, 273-285.

2.        Hays, V. W. et al. (1978). J. Anim. Sci. 46, 884-891.

3.        Maxwell, C. V. et al. (1994). J. Anim. Sci. 72, 3169-3176.

4.        Alexander, T.I.L, et al. (1980). Vet. Rec. 106, 114-119.