Changes in the activity of the sympathetic nervous system or in the hypothalamo-pituitary-adrenal axis have been extensively used to evaluate pain induced by castration or tail docking in numerous species. Such data are missing in pigs. Therefore, three experiments were conducted to determine the effects of castration, tail docking, or tooth resection on stress hormones. Glucose and lactate also were measured because catecholamines stimulate mobilization of glycogen, which results in glucose and lactate release. In Exp.1, 18 male pigs from seven litters (two or three pigs per litter) were catheterized surgically into one jugular vein, under general anesthesia, at 5 or 6 d of age. Two days later, they were submitted either to bilateral castration, control handling, or no handling (n = 6 per group). Blood samples were collected before (- 15 and -2 min) and after (5, 15, 30, 60, 90, 180 min) the experimental treatment. In Exp. 2, 27 female pigs from 12 litters (one to four pigs per litter) were submitted either to tooth clipping with pliers, tooth resection with a grinder apparatus, control handling, or no handling (n = 6 or 7 per group) at 1 d of age. In Exp. 3, 17 female pigs from nine litters (one to three pigs per litter) were submitted to one of the following treatments: 1) tail docking with an electric-heated scissor docking iron, 2) control handling, and 3) no handling (n = 5 or 6 per group) at 1 d of age. Castration induced significant (P < 0.05) increases in adrenocorticotropin hormone (ACTH; from 5 to 60 min), cortisol (from 15 to 90 min), and lactate (from 5 to 30 min). These variations are indicative of stress and tissue damage following castration. In contrast, neither tail docking nor tooth resection had marked effects on plasma cortisol, ACTH, glucose, and lactate. Measurements of plasma cortisol, lactate, and ACTH could be useful for validating treatments designed to relieve the distress reaction induced by castration in pigs.

No abstract

Effects of nutritional deficit during lactation on secretion of gonadotropic hormones and ovarian follicular populations around weaning were investigated in 24 primiparous crossbred sows. Sows were allocated to receive close to ad libitum intakes (H) or approximately 50% of this amount (L) during a 28-d lactation. Serial blood samples were collected 1 d before weaning (W-1), in the hours following weaning (W), and 1 d after (W+1). Their ovaries were removed on the day of weaning or 2 d later (W+2) and subjected to macroscopic and histological observations. Mean and basal LH concentrations were not influenced by the level of feeding. Frequency of LH pulses was reduced in L sows (.17, .5, and .5 vs 1.50, 1.17, and .83 pulses/6 h at d W-1, W, and W+1 respectively; P < .05). Mean and basal concentrations of LH were influenced by the day of sampling, being significantly increased within hours following weaning. Mean FSH concentrations were influenced neither by the level of feeding nor by the day of sampling. At weaning, the ovaries from L sows were lighter and had smaller follicles and fewer follicles > or = 4 mm (P < .05). Values of these macroscopic characteristics increased after weaning ( P < .05). At weaning, the percentage of healthy follicles was higher in the first class (< 1 mm) and lower in the second class (1 to 2.99 mm) in L compared to H sows (P < .05). Whatever the day of sampling, IGF-I concentrations in follicular fluid tended to be lower in L than in H sows. These results indicate that feed restriction during lactation inhibits LH pulsatility and ovarian activity.

No abstract

The effects of dietary levels of tryptophan (TRP) and protein on voluntary feed intake, growth performance, muscle pH, and brain indoleamine and catecholamine concentrations were studied in an experiment involving 48 crossbred Piétrain x Large White pigs (38 kg initial weight). Equal numbers of females, intact males, and barrows were used and they were given ad libitum access to feed during the 28-d experiment. Four dietary treatments were compared in a 2 x 2 factorial arrangement, with the following levels of analyzed TRP and CP: 1) .12 and .16% TRP, suboptimum and optimum for growth, respectively, 2) 12.7% CP of a diet based on corn-soybean meal and adequately balanced for limiting essential amino acids other than TRP; and 16.7% CP diet with additional protein from corn gluten meal. Dietary CP interacted with TRP on feed intake and growth, with a greater depressive effect at .12% TRP than at .16% TRP in the three genders. Norepinephrine concentration, which was the highest in the preoptic area, was higher in females than in intact or castrated males. Serotonin concentration was increased by TRP supplementation in the different brain regions. Additional CP depressed serotonin concentration more at .12% TRP than at .16% TRP. The greater sensitivity of feed intake and growth of pigs, especially females, to TRP deficiency in the presence of additional CP may have been related to a more critical serotonergic activity, when hypothalamic serotonin concentration fell below a threshold level. Supplemental TRP increased muscle pH, both at 45 min and 24 h after death, in ham (adductor femoris and semimembranosus) and loin (longissimus), suggesting a sedative effect of TRP for reducing stress response.

-Blood, colostrum and saliva samples were serially taken from 6 multiparous sows from day 109 of gestation until day 3 postpartum. Plasma was assayed for oestradiol-17β (E2), progesterone (P4), prolactin (PRL), cortisol, immunoglobulin G (IgG) and lactose. Colostrum was assayed for E2, P4, IgG and lactose. Lactoserum, obtained after ultra centrifugation of colostrum, was assayed for PRL. Saliva was assayed for cortisol. Time-related variations in hormone, IgG and lactose concentrations measured in plasma were parallel to those measured in colostrum, lactoserum or saliva. However, the concentrations were higher in colostrum or lactoserum and lower in saliva than in plasma. Ratios of concentrations of cortisol in saliva and PRL in lactoserum over those in plasma did not vary with time and averaged 0.2 and 1.6, respectively. Conversely, the ratios of concentrations of E2 and P4 in colostrum over those in plasma varied with time (P < 0.05) but were quite constant before the end of parturition, averaging 2.7 and 3.6, respectively. The ratios of concentrations of IgG and lactose in colostrum over those in plasma also varied with time (P < 0.05). The concentrations of hormones in plasma on the one hand and in colostrum, lactoserum or saliva on the other hand were significantly correlated but correlations varied with time (PRL across periods: r = 0.31; cortisol across periods: r = 0.60; E2 during parturition: r = 0.83; P4 before parturition: r = 0.82; P4 during parturition: r = 0.67). The present results indicate that around parturition, assays of hormones in colostrum or saliva can be used to study the hormonal status of sows. Furthermore, variations in colostrum and plasma concentrations of IgG and lactose are good indicators of the transition from colostrum to milk synthesis. sow / parturition / steroid / prolactin / lactose / immunoglobulins

We evaluated the effects of high ambient temperature and feed restriction in primiparous lactating sows. Females were exposed to either a constant thermoneutral (20°C ) or hot environment (30°C). Lactating sows at 30°C were given free access to feed (30AL; n = 12), and sows at 20°C were restricted according to the feed intake recorded at 30°C (20RF; n = 6 ) or were given free access to feed (20AL; n = 6). Jugular vein catheters were surgically inserted at 100 ± 1 d postcoitum. During lactation, 30AL sows exhibited higher rectal temperatures ( P < .05) than 20AL and 20RF sows. Feed intake was reduced by 43% for 30AL compared with 20AL sows. Daily body weight loss was lower ( P < .05) in the 30AL than in the 20RF group, and mean litter daily gain over the whole lactation was 18% lower in 30AL than in 20AL sows ( P < .05) and was intermediate in 20RF females. Plasma concentrations of thyroid hormones (triiodothyronine [T 3 ] and thyroxine [T 4 ] ) were lower at 30°C than at 20°C at d 4 postpartum and d 8 after weaning for T 4 ( P < .001) and at d 4 postpartum ( P < .001) and at d 1 and d 8 after weaning for T 3 ( P < .01) but were not influenced by feed restriction at 20°C. Mean concentrations of cortisol measured on d 4 and 19 postpartum and on d 1 after weaning were lower in the 30AL than in the 20AL group ( P < .05), and neither was different from that in 20RF sows. Ambient temperature and feed intake had no influence on prolactin concentrations on d 19 postpartum and d 1 after weaning. In the 30AL group, concentrations of T 3 , cortisol, and prolactin measured at d 19 postpartum were positively correlated with the litter gain observed during the 2nd and 3rd wk of lactation ( P < .05). The return to estrus was slightly delayed in 20RF compared with 20AL sows ( P < .05) and was quite variable in the 30AL group. These results demonstrate that high ambient temperature has negative consequences on litter growth and return to estrus and induces plasma hormonal variations, that cannot be fully mimicked by feed restriction in primiparous sows.

-Twenty-four primiparous sows were allocated at farrowing to a high (H: 5.5-6 kg feed/day) or a low (L: 2.5-3 kg/day) level of feeding. Litters (8-10 piglets) were weaned at 28 ± 2 days. Serial blood samples were collected 1 day before weaning (W-1 in the hours following weaning (W)