REMIXING LIGHTWEIGHT PIGS IN THE GROWER-FINISHER

A recent study has shown that sorting and regrouping lightweight pigs with pigs of similar size does not improve their growth performance and carcass characteristics. M. C. Brumm and coworkers (2002) hypothesized that managing variation in the nursery and grower-finisher by sorting and regrouping lightweight pigs might improve their performance. Five experiment stations (in Illinois, Iowa, Michigan, Minnesota, and Nebraska) cooperated in the study’s first experiment. Treatments used were:

1. 15 pigs per pen from approximately 58 pounds to market.
2. 20 pigs from 58 pounds to 154 pounds and then reduced to 15 pigs until market weight.
3. 15 pigs per pen from 154 pounds to market with groups made up using the five lightest pigs from Treatment 2.

Thus, pig performance after 154 pounds of body weight can be compared to determine differences between the management strategies.

Treatment 1 indicates the results when no remixing took place. Treatment 2 represents the pens with light pigs removed. Treatment 3 represents the pens with the lightest pigs combined into new pens. Floor space was maintained within treatments, and pigs were fed a four-phase, sepa-rate-sex diet program (1.00, 0.88, 0.73, and 0.60 percent lysine for barrows and 1.00, 0.93, 0.88, and 0.69 percent lysine for gilts from 58 to 255 pounds of body weight). Remixing pigs resulted in a group of pigs that was heavier (Treatment 2) and a group of pigs that was lighte (Treatment 3), compared to pigs that were left in their original groups. Pigs in the lightweight group grew more slowly and consumed less feed, compared to the other groups. To determine the effects of remixing, the combined performance results of pigs in Treatments 2 and 3 need to be compared to the performance of pigs in Treatment 1. Daily gain, feed intake, feed efficiency, and lean percent (containing 5 percent fat) were not different between the two management strategies. However, sorting of light-weight pigs resulted in a reduction in pen variation immediately following sorting, and this effect was still evident at slaughter.

In the second experiment, the same treatments were used as in Experiment 1. However, in this study, pigs were weaned at 17 days of age and remixed after three weeks (20.4 pounds of body weight). Pigs were housed in a wean-to-finish facility.

Similar to Experiment 1, removing lightweight pigs from Treatment 2 increased the average weight in that group following sorting and resulted in lower initial weights in Group 3. Lightweight pigs had poorer growth and feed intake compared to the other groups. However, when management strategies were compared (Treatment 1 vs. Treatments 2 and 3 combined), no differences in pig perfor-mance were observed. Although within-pen variation was reduced by sorting initially, variation was not different at the end of the experiment.

Brumm and coworkers concluded that removal of lightweight pigs and remixing in separate pens does not improve pig performance or decrease variation at market weight. The authors recognized that feeding diets formulated to more closely match the nutritional requirements of the lightweight pigs may have resulted in different results. Indeed, growth performance of lightweight pigs was always lower than that of their counterparts. In addition, the authors suggested that remixing the heaviest or the midweight pigs might have been more effective than remixing the lightweight pigs and therefore avoiding in the lightweight pigs the increased levels of stress associated with remixing.

Reference

Brumm, M. C., M. Ellis, L. J. Johnston, D. W. Rozeboom, D. R. Zimmerman, and NCR-89 Committee on Swine Manage-ment. 2002. Effect of removal and remixing of lightweight pigs on performance to slaughter weights. Journal of Animal Science 80:1166-72.

—Eric van Heugten

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DIFFICULT DECISIONS ON EUTHANASIA

By definition, euthanasia should be timely and humane; in practice, however, simultaneously achieving both goals on the farm can be difficult. Most managers intuitively understand that euthanasia is an important part of good husbandry, but that doesn’t necessarily make the actual process any easier to carry out for an individual affected animal. Also, the rapid industrialization of production agriculture, as exemplified in the swine industry, has brought about many changes, most notably fewer individuals with a farming background looking after the animals. Publicity following recent prosecutions of people mistreating animals during the euthanasia process has resulted in industry-wide concern with the issue of on-farm euthanasia.

Although peer-reviewed studies on the attitudes of farm-animal workers to the task of euthanasia are scarce, most farming people we ask state that they do not enjoy the task. In a survey of job satisfaction, farrowing managers reported the most dissatisfaction with their job (31.3% reporting their job satisfaction as 'needs changes' or 'poor') compared with managers (17.2%) assistant managers (26.9%) and herdsman (24.4%) (Kliebenstein, 1996). We surmise that at least a part of their dissatisfaction is associated with their job requirement of having to euthanatize many poor-doing piglets. For business in general, and for the agricultural animal industry in particular, hiring and retaining quality employees is a major responsibility of management and an increasingly difficult task. To help decrease labor turnover, management must be sensitive to factors contributing to employee unease and if it is related to euthanasia a special effort will be needed to resolve these issues.

We suspect farm workers’ attitudes to euthanasia vary according to their prior experience. For example, people raised on farms that have euthanatized animals before, or seen others do it, may be less likely to find it objectionable. Increasingly, the people working on farms do not have a farming background and have no prior experience of euthanasia. Part of the reason people dislike euthanatizing animals is that they transfer their fear and the unpleasant-ness they feel associated with the death of a human to the death of an animal. Farm managers must recognize differ-ences among people in their aversion to euthanasia and delegate the responsibilities accordingly. If people are constantly and reluctantly exposed to euthanasia they can experience dissatisfaction with their work, absenteeism, belligerence, or careless and callous handling of animals.

We are limited to methods of euthanasia that act through the mechanisms of direct neuronal depression, disruption of brain activity, and hypoxia to cause rapid unconsciousness and humane death. Regardless of the particular method, however, people are disturbed less by the euthanasia process when they feel distanced from the physical act of euthanasia or when animals exhibit little or no movement. For example, laboratory technicians reported they felt more comfortable gassing animals, where they were more dissoci-ated from the animals’ death, than directly killing the animal with cervical dislocation (Arluke 1999). Focus groups consisting of North Carolina swine farm managers have told us they would prefer euthanasia methods 'where you could give a shot and the animal goes to sleep' over the physical methods currently in use.

Because the euthanasia process must necessarily combine physical restraint of an animal with a lethal action or chemical agent, animal handlers are at risk for physical injury or even death. Less well understood, however, is that some farm workers suffer psychological distress when asked to euthanatize animals in their care. We believe this is a problem because farm managers tell us it is and researchers have documented the problem for companion animal handlers involved in the euthanasia process. Worker distress associated with on-farm euthanasia is a poorly understood area in production agriculture; who is most affected, how can their concerns be addressed, how can their distress be alleviated? An especially vexing industry problem is that of euthanatizing the well, but uneconomic, farm animal. Providing clear criteria for treatment or euthanasia of farm animals may relieve worker distress.

References

Arluke A: Occupational Medicine: State of the Art Reviews. 14:305-316. 1999.

Kliebenstein J, Hurley T, Orazem P. Personnel management issues and job satisfaction in pork production. Swine Extension Educators Conference. Des Moines, Iowa 1996.

—Morgan Morrow and Robert Meyer

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ON-FARM PERFORMANCE TESTING
The following breeders with validated herds have tested animals in the past 30 days.

Breeder	Address	Breeds
Bob Ivey*	314 N.C. 111 S, Goldsboro 27530	L, D, H, Y, CW, X
Wesley Looper*	4695 Petra Mill Rd., Granite Falls 28630	L, D, H, Y, X
Thad Sharp, Jr., & Sons	5171 N.C. 581 Hwy., Sims 2788030	D, Y, X
Tommy Spruill	Rt. 1, Box 149, Columbia 27925	L, X
Thomas Farms	8251 Oxford Rd., Timberlake 27583	X
UCPRS (Swine Dev. Center)	Rt. 2, Box 400, Rocky Mount 27801	X
Caswell Farm Unit	2415 W. Vernon Ave., Kinston 28501	X
*Real-Time Ultrasound

—Frank Hollowell and David Lee

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Last modified June 3, 2002.

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