A. Madej

Effect of a Gonadotropin-releasing Hormone Vaccine (ImprovacTM) on Steroid Hormones, Boar Taint Compounds and Performance in Entire Male Pigs

The objective of this study, comprising two trials, was to evaluate the effect of a gonadotropin-releasing hormone (GnRH [corrected] vaccine Improvac; Pfizer Ltd) in a sample of the Swedish pig population. The pigs (n = 120) were assigned to three groups: control (entire male pigs), surgical castration and immunization against GnRH. Surgically castrated pigs did not express detectable levels of either testosterone or estrone sulphate (E1S) in plasma, or androstenone in fat and had lower skatole and indole levels in fat than entire male pigs. Immunization significantly reduced testes weight and bulbourethral gland length, plasma levels of the testicular hormones testosterone and E1S, and fat levels of androstenone, skatole and indole. Skatole levels in plasma were significantly lower than in entire male pigs in the second trial, but not in the first due to overall low skatole levels. All immunized pigs and surgically castrated pigs expressed skatole concentrations in fat below the level of 0.2 microg/g, above which meat is regarded as tainted. In contrast, eight entire male pigs exceeded this level. Indole levels in plasma from immunized pigs were lower than those from entire male pigs. Surgical castration caused lower daily weight gain in the suckling period compared with piglets raised intact, whereas in the post-weaning period no difference was observed. Immunization resulted in higher feed intake and daily weight gain after the second injection. The estimated lean meat content was improved in comparison with the castrated pigs, but was lower than for entire male pigs. Dressing percentage was lower in immunized pigs than in surgically castrated and entire male pigs. The frequency of skin damage did not differ between immunized and entire male pigs or between immunized and surgically castrated pigs.

Blood levels of 15-keto-13, 14-dihydroprostaglandin F2α during the postpartum period in primiparous cows

Plasma levels of the PGF(2alpha) metabolite 15-keto-13, 14-dihydroprostaglandin F(2alpha) were determined postpartum in 51 primiparous Black and White Lowland cows. The highest geometric mean was 1702 pmol/l on day 3 and lowest 190 pmol/l on day 21. It should be noted that variation between animals in the concentration of the metabolite is high. For instance, on days 4, 10, 16 and 22, concentration of metabolite ranged from 775-2500, 209-2450, 45-851 and 30-398 pmol/l, respectively. The duration of the massive postpartum release of PGF(2alpha) could be determined in only 29 cows. Significant correlations were found between the duration of elevated PGF(2alpha) metabolite levels and the time required for completion of uterine involution (r = -0.41, P < 0.05) and between the duration of increased PGF(2alpha) metabolite levels and the interval from parturition to occurrence of the first ovulation followed by a normal luteal phase length (r = -0.37, P < 0.05). The occurrence of the first ovulation followed by a normal luteal phase length in the 29 cows was positively correlated with the time needed for completion of uterine involution (r = 0.54, P < 0.01).

Endocrine profiles and embryo quality in the PMSG-PGF2α treated cow

Plasma progesterone and LH concentrations around estrus were determined for both PMSG treated (experimental animals) and non-treated (control animals) dairy cows and heifers of the Holstein Friesian and Jersey breeds, and these hormone profiles were related to the embryo quality. Most experimental animals experienced an increase in progesterone concentrations following PMSG treatment and an abrupt decrease to values below 3 nmol/l after PG injection. The mean (+/-SE) intervals from prostaglandin treatment to estrus were 46.9+/-1.8 h and 64.5+/-4.8 h for experimental and control animals, respectively. At the onset of heat the progesterone concentration in experimental animals with optimal embryo quality (group I) was significantly lower (p<0.01) than in experimental animals which yielded unfertilized eggs (group II) (1.2+/-0.1 versus 3.9+/-0.8 nmol/l) and significantly higher than the level in the control group (0.6+/-0.1 nmol/l). Following estrus the progesterone profiles in all 3 groups were studied and the length of the superovulatory cycle was measured to 26.0+/-4.8 days. The preovulatory LH surge occurred sooner after prostaglandin injection in experimental (41 h) than in control animals (65 h). The LH surge in group I occurred within a narrow range and reached a higher average level than group II (24.2+/-2.2 ng/ml and 16.3+/-3.7 ng/ml, respectively). The control group attained an even higher LH surge (31.8+/-8.8 ng/ml) than did the experimental animals. The data presented in this experiment indicate that plasma levels of progesterone and LH in PMSG-PGF2alpha treated animals are related to embryo or egg quality.

Stress and its influence on reproduction in pigs: a review

The manifestations of stress, defined as a biological response to an event that the individual perceives as a threat to its homeostasis, are commonly linked to enhanced activity of the hypothalamo-pituitary-adrenal (HPA) axis and the activation of the sympathetic adreno-medullary (SA) system. Activation of the HPA system results in the secretion of peptides from the hypothalamus, principally corticotropin releasing hormone (CRH), which stimulates the release of adrenocorticotropic hormone (ACTH) and beta-endorphin. ACTH induces the secretion of corticosteroids from the adrenal cortex, which can be seen in pigs exposed to acute physical and/or psychological stressors. The present paper is a review of studies on the influence of stressors on reproduction in pigs. The effects of stress on reproduction depend on the critical timing of stress, the genetic predisposition to stress, and the type of stress. The effect of stress on reproduction is also influenced by the duration of the responses induced by various stressors. Prolonged or chronic stress usually results in inhibition of reproduction, while the effects of transient or acute stress in certain cases is stimulatory (e.g. anoestrus), but in most cases is of impairment for reproduction. Most sensitive of the reproductive process are ovulation, expression of sexual behaviour and implantation of the embryo, since they are directly controlled by the neuroendocrine system.

Sequential endocrine changes and behaviour during oestrus and metoestrus in repeat breeder and virgin heifers

Abstract The aim of the experiment was to study the oestrous behaviour and the peripheral blood plasma profiles of luteinizing hormone (LH), progesterone and the prostaglandin metabolite, 15-keto-13,14-dihydro-PGF2α, during oestrus and metoestrus in repeat breeder (RBH) and virgin heifers (VH). Ten animals of each category were utilized. The RBH had a history of at least three inseminations without conception, and the VH were sexually mature animals not previously inseminated or mated. Oestrous symptoms were recorded and blood collected from the onset of prooestrus to 7 days after oestrus. The animals were inseminated during oestrus and their embryos were collected by a nonsurgical technique 7 days after insemination. The morphology of the embryos was evaluated. The duration of oestrus was longer (P The result of the study indicates a hormonal imbalance in the RBH. The hormonal asynchronism starts before or early in oestrus, which presumably leads to a sequence of improper hormonal changes responsible for the elevated embryonic loss in repeat breeder animals.

Effect of food deprivation during early pregnancy on endocrine changes in primiparous sows

Abstract The effect of food deprivation during early pregnancy on maternal plasma endocrine levels and on embryonic survival was studied in primiparous sows. Twelve cross-bred (Swedish Yorkshire × Swedish Landrace) primiparous sows at the same stage of pregnancy were used. Six sows were fasted on Days 10 and 11 of pregnancy, with free access to water. The other six sows were fed as usual and used as controls. Blood samples were collected from Days 7 to 14 of pregnancy for cortisol, corticosteroid-binding globulin (CBG), progesterone (P4), oestradiol-17β (E2), oestrone sulphate and prostaglandin F2α metabolite (PG-metabolite) analysis. The sows were slaughtered on Day 17 of pregnancy and embryos recovered. Cortisol concentrations rose (P

Modulation of porcine cytochrome P450 enzyme activities by surgical castration and immunocastration

The present study aimed to evaluate some cytochrome P450 metabolic enzyme activities in hepatic microsomes prepared from entire male pigs (uncastrated pigs), surgically castrated pigs and pigs immunized against gonadotropin-releasing hormone (immunocastrated pigs). The activities of the following enzymes were measured: ethoxyresorufin O-deethylase (EROD, CYP1A1/1A2), methoxyresorufin O-deethylase (MROD, CYP1A2), pentoxyresorufin O-depentylase (PROD, CYP2B), coumarin hydroxylase (COH, CYP2A) and p-nitrophenol hydroxylase (PNPH, CYP2A/2E1). The total cytochrome P450 contents were not affected by either surgical or immunocastration. Hepatic microsomal activities for EROD, PROD, COH and PNPH were lower in entire male pigs compared with surgically castrated and immunocastrated pigs (P < 0.05). Surgically and immunocastrated male pigs were similar with respect to EROD, MROD, PROD and COH activities (P > 0.05), whereas surgically castrated pigs exhibited lower PNPH activity compared with immunocastrated pigs (P = 0.029). The effect of different concentrations of testicular steroids - testosterone, 17β-estradiol, free estrone and androstenone - on enzyme activities was evaluated by in vitro microsomal study. Testosterone at the concentration of 8 pmol/ml inhibited EROD activities and estradiol-17β at the concentration of 1.8 pmol/ml inhibited PROD activities in hepatic microsomes from surgically castrated pigs. The highest concentration of androstenone (7520 pmol/ml) inhibited COH activities, whereas a 42-fold lower concentration of androstenone (180 pmol/ml) stimulated COH activities in surgically castrated pigs. Both free estrone (3.5 pmol/ml) and androstenone (55 pmol/ml) inhibited EROD activities in microsomes from entire male pigs. Stimulation of COH activities by the highest dose of free estrone (18 pmol/ml) was recorded in microsomes from entire male pigs. However, these effects of steroids were not concentration-dependent and the maximum extent did not exceed ±15% variation compared with the controls. There was no inhibition of PNPH activities in the hepatic microsomes from either entire or castrated pigs. In conclusion, we showed that EROD, PROD, COH and PNPH activities were lower in entire male pigs compared with those in surgically and immunocastrated pigs. Direct inhibition by the testicular steroids - testosterone, 17β-estradiol, free estrone and androstenone - was not the primary cause of the reduced enzyme activities.

The influence of stress on early pregnancy in the pig

Abstract The manifestations of stress, defined as disturbances of homeostasis, are commonly linked to enhanced activity of the hypothalamo-pituitary-adrenal (HPA) axis and the activation of the sympathetic adreno-medullary (SA) system. Activation of the HPA system results in the secretion of peptides from the hypothalamus, principally corticotropin releasing hormone (CRH), which stimulate the release of β-endorphin and adrenocorticotropic hormone (ACTH) from the hypothalamus and pituitary. ACTH induces the secretion of corticosteroids from the adrenal cortex, which can be seen in pigs exposed to acute physical and/or psychological stressors. Stress is considered to be associated with a decrease in reproductive functions. The causes of extreme stress may include new social grouping, food deprivation and poor thermoregulation. A brief review is given on current knowledge of these stressors and their impact on early pregnancy in the pig.

Early immunocastration of male pigs with Improvac ® - Effect on boar taint, hormones and reproductive organs

The aim of this study was to investigate the effect of a vaccine against gonadotropin-releasing hormone (GnRH), Improvac(®) (Pfizer Ltd), administered at a pre- or early pubertal stage on boar taint, hormonal status and reproductive organs. Crossbred male pigs (Swedish Yorkshire dams×Swedish Landrace sires or Swedish Yorkshire sires, n=192) were at birth randomly allocated to four groups: one group of pigs surgically castrated without anaesthesia before age 1 week, a second group of early vaccinated pigs given Improvac at ages 10 and 14 weeks, a third group of standard vaccinated pigs given Improvac at ages 16 and 20 weeks, and a fourth group of entire male pigs. Following the second vaccine injection, antibody titres increased rapidly, accompanied by a rapid decrease in testosterone and a slower decrease of skatole in plasma to the same low levels as for surgically castrated pigs. At slaughter, the levels of androstenone and skatole in adipose tissue were low in surgically castrated and vaccinated pigs, whereas entire male pigs had elevated levels (p<0.001). Similarly, oestradiol was at low levels for surgically castrated and vaccinated pigs, whereas entire male pigs had elevated levels (p<0.001). IGF-1 was lowest for surgically castrated pigs and highest for entire male pigs, with vaccinated pigs at an intermediate level (p<0.001). At slaughter, reproductive organs were small in pigs vaccinated with Improvac, and smaller in pigs vaccinated early (p<0.001). Under our experimental conditions, early vaccination with Improvac can be used as an alternative to the recommended schedule with maintained control of boar taint and testicular secretory activity.

Effects of post-ovulatory food deprivation on oviductal sperm concentration, embryo development and hormonal profiles in the pig.

Nutrition is one of the multiple factors that modulate reproduction in animals. The effect of 48 h food deprivation on reproductive and metabolic hormonal changes in relation to cleavage rates was studied. Insemination of 15 sows was performed 20-10 h prior to expected ovulation and ova were recovered at slaughter 65-91 h post ovulation. Blood samples were collected every second hour, beginning from the time of insemination until slaughter, for measurements of progesterone, cortisol, the prostaglandin F2alpha metabolite (15-keto-13,14-dihydro-PGF2alpha) and insulin levels. The embryos from the food-deprived sows (D-group) had fewer accessory spermatozoa in their zona pellucida (ZP) compared with the control sows (C-group). A lower cleavage rate of the embryos in the D-group compared with the C-group was detected. Plasma progesterone, cortisol and prostaglandin F2alpha metabolite levels were significantly higher in the D-group compared with the C-group. Food deprivation is associated with changes in reproductive and metabolic hormones that might lead to changes in the oviductal environment, culminating in a lower cleavage rate of the embryos and presence of fewer viable spermatozoa in the reservoir.