Øystein Andresen

Estimation of genetic parameters of boar taint; skatole and androstenone and their correlations with sexual maturation

Boar taint is mainly caused by two components; skatole (3-methylindole) and androstenone. By castrating the male pigs, boar taint will be avoided. In Norway, castration of pigs will no longer be permitted after 2009. This represents a substantial cost for the Norwegian swine production. Other Norwegian studies have shown that a large proportion of pigs are above the consumer detection limits for these two chemical components. The obvious question for the geneticist arises: Is it possible to select against skatole and androstenone in a breeding programme? Skatole is produced in the gut by bacteria. It is then absorbed in the blood stream. Skatole is either metabolised in the liver or transported and stored in fatty tissue. Androstenone is produced in the testis, and its biochemical pathway is related to the pathway of testosterone. In this study, fatty tissue was collected from the carcasses of Norwegian Landrace and Duroc boars, and analysed for androstenone and skatole. The length of glandula bulbourethralis was measured on the same animals, as this is regarded as a good indicator of sexual maturation. Heritabilities of androstenone and skatole were substantial. The two components were genetically correlated. Sexual maturation was also highly heritable. However, correlations to both androstenone and skatole were significantly unfavourable.

Effect of Toxoplasma gondii infection on the development of pregnancy and on endocrine foetal-placental function in the goat

The effect of Toxoplasma gondii inoculation on pregnancy and on endocrine foetal-placental function in pregnant goats was studied. Five susceptible goats were inoculated subcutaneously with T. gondii bradyzoites at 71 +/- 2 days of gestation. Another five goats were used as controls. Plasma was analysed for progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha. The condition of the foetuses was monitored by real-time ultrasonography. All inoculated goats aborted or delivered stillborn or weak kids 54-73 days after inoculation. None of the goats showed signs of general disease. In cases of foetal death, the ultrasound examination revealed that death occurred between day 1 and 12 before abortion or birth. The appearance of the foetuses varied from fresh to mummified, depending on the number of days between foetal death and expulsion. All five goats became serologically positive to T. gondii after inoculation. None of the goats used as controls aborted, but one goat delivered one mummified and one weak kid for unknown reasons. In inoculated animals an increase in 15-ketodihydro-PGF2 alpha levels in plasma and a subsequent tendency to a decrease in oestrone sulphate levels were observed from about day 40 after inoculation and until abortion or birth. High levels of 15-ketodihydro-PGF2 alpha were seen after foetal death. High levels of 15-ketodihydro-PGF2 alpha were not always followed by a drop in progesterone levels. The mean level of progesterone was slightly decreased after inoculation and onwards. The pattern of progesterone levels around abortion in the inoculated goats was very similar to the pattern around parturition in the control goats. However, 15-ketodihydro-PGF2 alpha levels were higher both before and after abortion in inoculated goats than in control goats. The level of oestrone sulphate did not increase in the inoculated group before abortion in contrast to the level in goats which delivered healthy kids. The patterns of changes in levels of 15-ketodihydro-PGF2 alpha and oestrone sulphate in inoculated animals indicate that the endocrine foetal-placental function was disturbed in most of the inoculated goats, probably due to the injury caused by the establishment and development of T. gondii infection in the placenta and foetus.

Foetal loss in dairy goats: An epidemiological study in 22 herds

Abstract In this study, 22 herds comprising 1439 dairy goats presumed to be pregnant were studied during the gestation period 1990–91. Altogether, 160(11.1% of the total number of goats) experienced foetal loss following conception. In all, 85(53%) of these goats aborted, 45(28%) delivered dead foetuses at full term and from 30(19%) goats no discharge or foetus was observed. The incidence of foetal loss in the different herds varied from 3–38%. The proportion of foetal loss was >20% in three herds comprising a total of 169 goats. In 10 herds comprising 677 goats the proportion of foetal losses were

Pregnancy diagnosis in dairy goats using progesterone assay kits and oestrous observation

Two qualitative on-farm milk progesterone test kits were used for early pregnancy diagnosis in goats. One kit was based on latex agglutination (LA) and the other on enzyme-linked immunosorbent assay (ELISA). The accuracy of early pregnancy diagnosis by these two methods was compared with the accuracy of oestrous observation (OeO) and the level of plasma progesterone measured by radioimmunoassay (RIA). Dairy goats (n = 73) from a single herd were used for collection of milk and blood samples 20 days after breeding. Ultrasound examination 50 days after mating found that 49 (67%) goats were pregnant, and 24 (33%) were not pregnant. Using ultrasound as a reference method, the accuracy of early pregnancy diagnosis by RIA and OeO was 92% and 86%, respectively, and for non-pregnancy 100% for both RIA and OeO. The accuracy of early pregnancy diagnosis by ELISA and LA was 82% and 79% and for non-pregnancy, 88% and 100%, respectively. The kappa-statistic for RIA, OeO, ELISA and LA was 0.93, 0.84, 0.77 and 0.73, respectively. It was concluded that LA and ELISA tests can be used for early pregnancy diagnosis in dairy goats. However, in the herd studied, early pregnancy diagnosis by OeO was as good as that achieved with progesterone determination using the kits.

Boar taint related compounds: Androstenone/skatole/other substances

Introduction Two substances are the main contributors to boar taint in pork from entire male pigs i.e. the steroid androstenone (5α-androst-16-ene-3-one) [1] and skatole (3-methylindole) [2,3]. The relative contribution of these substances to boar taint varies in different studies. Other substances may also contribute to a minor degree and a range of substances with an off-odour/off-flavour has been identified in boar fat. Among these indole and other 16androstene steroids may be of some significance [4,5].

Effects of hCG Stimulation on Hepatic Activities of Cytochromes P4502E1 and P4502A in Pubertal Male Pigs

The effects of human chorionic gonadotropin (hCG) stimulation on fat skatole concentrations and hepatic activities of cytochromes P4502E1 (CYP2E1) and P4502A (CYP2A) were studied in Landrace and Duroc breeds of entire male pigs. Pigs were divided into four groups: two control groups of each breed, without hCG stimulation (n = 20 for each breed), and two experimental groups of each breed, with hCG stimulation (n = 18 for each breed). Pigs were slaughtered 3 days after hCG stimulation and activities of CYP2E1 and CYP2A were measured in liver homogenate. Activities of both CYP2E1 and CYP2A were lower in hCG-stimulated pigs than control pigs for both Landrace (p = 0.005 for CYP2E1, p = 0.016 for CYP2A) and Duroc breeds (p = 0.003 for CYP2E1, p = 0.001 for CYP2A), and skatole concentrations in fat were higher in the hCG-stimulated pigs of both breeds (p < 0.01). For both control and hCG-stimulated groups, Duroc pigs had lower skatole concentrations than Landrace pigs (p = 0.001 for both groups). The activity of CYP2E1 did not differ significantly between breeds in either the control group or the experimental group (p = 0.233 for control pigs and p = 0.210 for experimental pigs). However, whereas CYP2A activity did not differ significantly between breeds in the control groups (p = 0.181 for CYP2A), in the hCG-stimulated groups, CYP2A activity was lower in Duroc pigs than in Landrace (p = 0.011). Based on these findings, we conclude that hCG stimulation can suppress hepatic CYP2E1 and CYP2A activities, probably through an increase in the levels of testicular steroids. Between-breed variations in skatole levels in fat were not related to the activities of CYP2E1 and CYP2A.

Foetal loss in dairy goats: function of the adrenal glands, corpus luteum and the foetal–placental unit

To investigate the causes and mechanisms of foetal loss in Norwegian dairy goats, blood parameters in 40 goats that lost foetuses were compared with those in 40 goats that experienced a normal pregnancy. High mean levels of 15-ketodihydro-PGF2alpha, and low mean levels of oestrone sulphate throughout pregnancy were associated with foetal loss. The mean oestrone sulphate level was low before abortion, and the distinct peak that occurred at parturition in the control goats was not observed in connection with abortion. Association of other blood parameters with foetal loss was not detected. Infectious agents and toxins did not appear to be major causes of foetal loss in this study. The normal level of progesterone and cortisol in goats with foetal loss indicated that the function of the corpus luteum and adrenal glands, respectively, were not disturbed. The rapid decline in progesterone level associated with foetal loss may therefore be a result, rather than the cause, of foetal death. The lowered level of oestrone sulphate and elevated level of 15-ketodihydro-PGF2alpha in goats with foetal loss clearly indicated that the endocrine foetal-placental function was disturbed.

In vitro and In vivo Association of Porcine Hepatic Cytochrome P450 3A and 2C Activities with Testicular Steroids

The aim of this study was to screen the inhibitory potential of several testicular steroids on cytochrome P450 3A (CYP3A) and 2C (CYP2C) activities in porcine liver microsomes. The microsomes used in this study were obtained from pubertal male pigs of two breeds, Landrace and Duroc. For the in vitro inhibition study, porcine microsomes were incubated in the presence of 17β-estradiol, 17α-estradiol, androstenone, dehydroepiandrosterone and dihydrotestosterone. Both reversible and mechanism-based inhibitions were examined. 7-benzyloxyresorufin (BR) and 7-benzyloxy-4-trifluoromethylcoumarin (BFC) were used as substrates for CYP3A, and diclofenac and tolbutamide (TB) as substrates for CYP2C. 7-benzyloxyresorufin O-dealkylase (BROD) activity was inhibited by all tested steroids in the microsomes from Landrace pigs via mechanism-based mode, but in the microsomes from Duroc pigs, BROD activities were inhibited only in the presence of 17β-oestradiol. Mechanism-based inhibition of BFC metabolism by the tested steroids was observed in the microsomes from both breeds, but this inhibition was weak and did not exceed 20%. TB hydroxylase (TBOH) activity in the microsomes from Duroc pigs was inhibited by 17α-oestradiol through the mechanism-based mode of inhibition. None of the investigated steroids inhibited TBOH activity in Landrace pigs. For the in vivo study, male pigs were injected with a single dose of human chorionic gonadotropin (hCG) to stimulate testicular steroid production by the Leydig cells. In vivo stimulation with hGC did not alter BROD activity either in Landrace or in Duroc pigs. BFC metabolism was significantly induced by hCG stimulation in both breeds and TBOH activity only in Duroc pigs. Activity of diclofenac hydroxylase was not detected in either Landrace or Duroc pigs. Breed significantly affected BROD and TBOH activity with BROD being higher in Landrace and TBOH in Duroc pigs. This study improved our understanding of the role of testicular steroids in the regulation of porcine CYP450 activity.

Steroidogenesis in primary cultures of neonatal porcine Leydig cells from Duroc and Norwegian Landrace breeds

Breed differences in steroidogenic activity between primary Leydig cells derived from neonatal purebred Duroc and Norwegian Landrace boars were investigated in vitro. Concentrations of testosterone, estradiol, androstenone, cortisol and progesterone produced into the medium were determined. To explore underlying mechanisms the cellular expression of a suite of genes relevant in steroidogenesis was measured using reverse transcription and quantitative PCR (RT-qPCR). Basal steroid concentrations indicated a larger production capacity for steroids in unstimulated Duroc cells. Stimulation of the cells with LH increased steroid hormone secretion significantly in both breeds in a dose dependent manner. Testosterone and androstenone concentrations increased approximately 50- and 15-fold, respectively, whereas concentrations of estradiol, cortisol and progesterone increased to a lesser extent. At levels of maximal LH stimulation, absolute steroid concentrations were higher in Duroc. However, the relative increase in hormone concentrations was significantly lower in Duroc cells for estradiol, progesterone and cortisol when compared to basal levels. LH exposure was associated with a general up-regulation of mRNA levels for steroidogenic genes, stronger in Duroc than in Norwegian Landrace. This was in agreement with the higher absolute concentrations of steroid hormones measured in culture medium from the LH-stimulated Duroc Leydig cells, but did not concur with the fact that the relative increase in hormone production was lower in Duroc than in Norwegian Landrace Leydig cells for some hormones. It was concluded that breed differences in steroid hormone concentrations and gene expression between Norwegian Landrace and Duroc are complex and cannot be explained by a simple mechanism of action.

Effect of type of roughage and energy level on reproductive performance of pregnant goats

Wilted grass silage of good quality from tower silos, silage of poor quality from aerobically damaged round bales, or barn-dried grass hay was used as the roughage component of the diet fed to 188 goats over 2 years. The goats were fed roughage ad libitum plus 400 g concentrate kg−1 milk for the first 90 days of gestation. From Day 91 to Day 120 of pregnancy they received either roughage ad libitum with supplementation of 100 g concentrate per goat day−1 or were fed only roughage to 70% of maintenance energy requirement. From Day 121 of pregnancy until kidding the feed consisted of 200 g hay, good silage ad libitum and 900 g concentrate per animal day−1. Reproductive losses were significantly higher (P < 0.01) in goats fed silage of poor quality compared with those fed hay or good silage in both experiments. Low energy feeding between Day 91 and Day 120 of pregnancy caused an increase (P < 0.01) in the rate of abortion in goats fed poor silage. Reproductive losses were lowest and number of kids born per goat after normal pregnancy were highest in goats fed good silage, irrespective of the energy level. Listeria monocytogenes was identified as the cause of abortion in five of the 43 goats that aborted. The rate of abortion was higher in older than in younger goats. Feeding silage of poor quality combined with low energy in the period of 91–120 days of gestation increased the rate of abortion in goats. Underfeeding with roughage of good quality during the same period had no influence on the rate of abortion.