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United States Department of Agriculture

Agricultural Research Service

Title: HORMONAL PROFILES, BEHAVIORAL RESPONSES, AND SHORT-TERM GROWTH PERFORMANCE FOLLOWING CASTRATION OF PIGS AT 3, 6, 9, OR 12 DAYS OF AGE

Authors
item Carroll, Jeffery
item Berg, Erika - UNIVERSITY OF MISSOURI
item Strauch, Trista - UNIVERSITY OF MISSOURI
item Roberts, Mary - UNIVERSITY OF TENNESSEE
item Kattesh, Hank - UNIVERSITY OF TENNESSEE

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 23, 2006
Publication Date: May 1, 2006
Citation: Carroll, J.A., Berg, E.L., Strauch, T.A., Roberts, M.P., Kattesh, H.G. 2006. Hormonal profiles, behavioral responses, and short-term growth performance after castration of pigs at three, six, nine, or twelve days of age. Journal of Animal Science. 84:1271-1278.

Interpretive Summary: Male pigs in U.S. swine production systems are routinely castrated to eliminate boar taint in pork, as well as to decrease aggressive behaviors and handling difficulties often encountered with intact male pigs. The optimal age at which a male pig should be castrated to minimize effects on performance and well-being remains an area of debate in both scientific and production communities. It has been demonstrated that pigs castrated after weaning, or at several weeks of age as opposed to several days of age, exhibit a greater negative behavioral and physiological response to castration. Hence, castration before weaning is currently recommended. Nevertheless, in pigs less than 21 d of age, the optimal age to castrate is not clear. The objective of the present study was to determine the effects of castration on overall stress and well-being in 3-, 6-, 9-, or 12-day-old pigs using endocrine measurements, short-term growth performance, and behavior as indicators. For this study, we used 90 intact male pigs which were assigned randomly to a treatment age by litter (3, 6, 9, or 12 days of age; n = 9 to 13 pigs per treatment/age group). Pigs within a single litter were then assigned to non-castrated (NC) or castrated (CAS) treatment groups according to body weight. Pigs were non-surgically fitted with jugular catheters, and blood samples drawn immediately before castration (time 0), and at 0.5, 1, 1.5, 2, 24 and 48 hours after castration. Body weights were obtained when the pigs were catheterized and again at 24 and 48 hours after castration. Minimizing stress to the young pig is essential for pig well-being and optimal performance. Castration causes stress to the young pig, regardless of age; however, the present results indicate that as a pig ages, the stress caused by castration and/or handling increases. Therefore, when making management decisions with regard to procedures that require animal restraint, the potential for handling stress and how it is influenced by age should be considered.

Technical Abstract: The objective of this study was to determine the effects of castration on short-term growth performance, hormone profiles, and behavior in pigs at 3, 6, 9, or 12 d of age. Ninety intact male pigs were assigned randomly to a treatment age by litter (3, 6, 9, or 12 d of age; n = 9 to 13 pigs per treatment/age group). Pigs within a single litter were then assigned to non-castrated (NC) or castrated (CAS) treatment groups according to BW. Pigs were non-surgically fitted with jugular catheters, and blood samples drawn immediately before castration (time 0), and at 0.5, 1, 1.5, 2, 24 and 48 h after castration. Body weights were obtained when the pigs were catheterized and again at 24 and 48 h after castration. Serum samples were analyzed for cortisol, porcine corticosteroid-binding globulin (pCBG), and dehydroepiandrosterone sulfate (DHEA-S). No differences (P = 0.88) were detected in initial BW of pigs, and there was no overall treatment effect on growth performance of pigs at 24 (P = 0.98) or 48 h (P = 0.94) post-treatment. There was a time x treatment effect (P < 0.01) for serum cortisol concentrations, such that cortisol was greater in CAS pigs compared to NC pigs. There was no overall effect of age at castration on cortisol concentrations (P = 0.59). At 24 h after castration, serum cortisol concentrations returned to baseline in all treatment groups (P = 0.24); however, at 48 h after castration, overall cortisol concentrations were elevated (P < 0.01) in the 6-, 9- and 12-day-old pigs in both the CAS and NC groups compared with baseline concentrations. Total cortisol and pCBG were used to calculate the free cortisol index (FCI). There was a time x treatment effect (P < 0.01) on the FCI, such that FCI was greater in CAS males than in NC males. There also was an overall effect of age on the FCI (P < 0.01). There was a time x treatment x age interaction (P < 0.01) for serum DHEA-S, such that DHEA-S concentrations decreased in CAS animals but increased in NC animals, and DHEA-S concentrations increased with age. During the first 2 h after castration, there was an overall age effect (P = 0.01) on the time that pigs spent standing, such that 3-d-old pigs stood more than 6-, 9-, or 12-d-old pigs. There was no treatment effect (P > 0.20) on the time pigs spent nursing, lying, standing or sitting, although there was a trend (P = 0.08) for CAS pigs to be less active than NC pigs. These data indicate that castration is stressful regardless of age; however, the stress associated with handling seems to increase as the pig ages.

Last Modified: 9/1/2014
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