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Preparturient sows were randomly assigned to either a farrowing crate (n = 12) or farrowing pen (n = 12) across cool and hot seasons (with or without drip cooling) to study space allocation and temperature effects on periparturient maternal behaviors, steroid concentrations, and piglet growth rates. Concentrations of estradiol-17 beta (E2 beta), progesterone (P4), and cortisol were quantified in blood collected from surgically implanted vena cava cannulas. Sows were videotaped from 2 h before to 2 h after farrowing. Similar periparturient behaviors were displayed by all sows, regardless of farrowing environment. Sows in pens had lower (P < .05) prepartum P4 concentrations from d -6 to the day preceding farrowing and a reduced (P < .05) piglet birth interval compared with sows in crates (12.95 +/- 1.35 min vs 18.31 +/- 2.21 min, respectively). Additionally, compared with multiparous sows in crates, multiparous sows in pens weaned heavier piglets (P < .05). Estradiol-17 beta concentrations were lower (P < .01) throughout lactation during hot weather for sows with or without drip cooling, averaging 9.30 pg/mL and 8.57 pg/mL, respectively, compared with 18.65 pg/mL for sows during cool weather. This decrease in E2 beta concentration in sows during hot weather was correlated with an extended (P < .05) interval from weaning to first estrus for the sows in hot weather compared to sows during cool weather. Cortisol concentrations decreased progressively during lactation and were not associated with litter weight gains or the interval between weaning and first estrus.

Male piglets are castrated primarily to prevent the unpleasant odours and flavours of entire male pig meat (boar-taint). Although castration can be legally performed without analgesia in the first seven days of life, available evidence shows that castration at any age is painful and may have a detrimental influence on health. Few anaesthetics or analgesics are licensed for use in piglets. The known methods for general and epidural anaesthesia cannot be run at the farm level for practical and/or legal reasons. Use of the local anaesthetic lidocaine is easy and allows the pain resulting from castration to be alleviated. Local destruction of testicular tissue by intra-testicular injection of chemical compounds (salts and acids) is an alternative to surgical castration but needs further investigation regarding welfare improvement and boar taint reduction. Immunocastration, by which castration is achieved using active immunisation (anti–GnRH immunisation) is an efficient alternative to surgical castration; however, there are no licensed vaccines in the EU and the consequences, in terms of pig welfare as well as its acceptability among EU consumers, need further evaluation.

Corticotropin-releasing hormone (CRH) has been implicated as an important mediator of behavior, immune, and neuroendocrine systems in animals experiencing stress, but its effects on these systems have not been evaluated in an integrated whole animal model. In this experiment we injected porcine and rat CRH (pCRH and rCRH) intracerebroventricularly (icv) and simultaneously and chronologically monitored acute changes in behavior, endocrine, and immune function in the pig. PBS or CRH (15, 50, and 150 micrograms pCRH and 15 and 150 micrograms rCRH) was injected icv, and serial blood samples were collected via an indwelling jugular catheter so that behavior could be monitored simultaneously. The central administration of pCRH and rCRH induced immediate dose-dependent behavioral and physiological responses. Pigs receiving 15 micrograms of either pCRH or rCRH had increased plasma ACTH and were hyperactive and vocal. However, when higher doses (i.e. 50 or 150 micrograms) were administered icv, the endocrine and behavioral responses were accompanied by a profound suppression of Concanavalin-A-induced lymphocyte proliferation. For example, pigs receiving 150 micrograms pCRH had increased plasma ACTH and motor activity at 10 min (P < 0.01) and suppressed lymphocyte proliferation at 30 min (P < 0.001). Whereas ACTH secretion declined after 40 min, the lymphocyte suppression and increased motor activity were sustained, suggesting different control mechanisms. It is suggested that although ACTH and cortisol may have negative feedback effects on ACTH secretion, they did not have these effects on the behavioral action of CRH. Furthermore, although the lowest dose of CRH (15 micrograms) induced motor activity and ACTH secretion, higher doses (50 or 150 micrograms) were necessary for suppression of mitogen-induced lymphocyte proliferation. These findings demonstrate that CRH in the pig brain is active for inducing simultaneous changes in behavioral and physiological systems and are, therefore, consistent with the hypothesis that brain CRH is important in mediating the interaction among behavior, endocrine, and immune systems in animals experiencing stress.

The effect of daily or interval (every 3 d) feeding on body weight change, blood glucose and cholecystokinin (CCK) concentrations, immune function, and behavioral activity were determined during the gestation period of sows. Sows were fed a corn-soybean meal diet either 2 kg daily or 6 kg once every 3rd d (interval). Body weight changes for the 42-d trial period were not different (P > .05) between regimens. Blood glucose concentrations were similar before feeding (P > .05). Two hours after feeding, glucose concentrations increased in interval-fed sows but not in daily-fed sows (P < .05). Premeal plasma CCK concentrations were greater for daily-fed sows than for interval-fed sows (P < .05). The CCK concentrations in sows of both regimens increased after feeding above premeal levels (P < .05), and interval-fed sows exhibited higher concentrations than daily-fed sows (P < .05). Immune function as evaluated through mitogen-induced proliferation of T cells was greater in daily-fed sows than in interval-fed sows (P < .05). Daily-fed sows were more active overall and on any given day than interval-fed sows (P < .05) and thus seemed to expend more energy. Further, daily-fed sows exhibited higher levels of mouth-based activities (i.e., sham chewing, licking, appetitive and consummatory feeding behavior, and excess drinking) than sows restricted to consumption of one large meal every 3rd d. These indicators suggest that feeding motivation significantly affected overall performance of sows. This study emphasizes the need for evaluating the impact of feeding regimens and meal size on feeding motivation and, ultimately, on the well-being of the gestating sows.

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