Influence of lactation length and gonadotrophins administered at weaning on fertility of primiparous sows

The aim of this study was to determine the effect of lactation length and treatment with gonadotrophins at weaning on reproductive performance of primiparous sows. After 3 wk of lactation, primiparous sows were either weaned (W3; n=273) or received a 7-d-old foster litter for a further 14 d of suckling (W5; n=199). At final weaning (3 wk or 5 wk lactation) sows were randomly assigned to receive an injection of 400 IU equine chorionic gonadotrophin plus 200 IU human chorionic gonadotrophin (PG600(®); W3 + P; n=108 and W5 + P; n=96) or no injection (W3; n=165 and W5; n=103). Sows were inseminated at first observed estrus after final weaning and 24h later. The proportion of sows showing estrus by 6 d post-weaning was greater (P<0.01) for W3+P (86%) compared to W3 (64%), however, there was not a difference (P=0.13) for W5 + P (79.4%) compared to W5 (69.1%). There was no effect of either lactation length or gonadotrophin treatment on farrowing rates or on the proportion of sows culled before breeding. Total born litter size was smaller (P=0.05) for W3 + P (11.7 ± 0.4) compared to W3 (12.6 ± 0.3). However, sows that lactated for 35 d had larger litters than sows that lactated for 21 d regardless of gonadotrophin treatment (14 ± 0.5 and 14.5 ± 0.4 for W5+P and W5, respectively; P<0.001). These data indicate that for primiparous sows, a longer lactation improves total born litter size at their next farrowing. Gonadotrophin treatment is useful in shortening the weaning to estrus interval but subsequent total born litter size may be negatively affected.

Opportunities for genome-wide selection for pig breeding in developing countries

Genetic improvement of exotic and indigenous pigs in tropical developing countries is desired. Implementations of traditional selection methods on tropical pig populations are limited by lack of data recording and analysis infrastructure. Genome-wide selection (GS) provides an approach for achieving faster genetic progress without developing a pedigree recording system. The implications of GS on long-term gain and inbreeding should be studied before actual implementation, especially where low linkage disequilibrium (LD) is anticipated in the target population. A simulation case study of this option was performed on the basis of the available 60,000 SNP panel for porcine genome. Computer simulation was used to explore the effects of various selection methods, trait heritability, and different breeding programs when applying GS. Genomic predictions were based on the ridge regression method. Genome-wide selection performed better than BLUP and phenotypic selection methods by increasing genetic gain and maintaining genetic variation while lowering inbreeding, especially for traits with low heritability. Indigenous pig populations with low LD can be improved by using GS if high-density marker panels are available. The combination of GS with repeated backcrossing of crossbreds to exotic pigs in developing countries promises to rapidly improve the genetic merit of the commercial population. Application of this novel method on a real population will need to be performed to validate these results.

Persistency of accuracy of genomic breeding values for different simulated pig breeding programs in developing countries

Genetic improvement of pigs in tropical developing countries has focused on imported exotic populations which have been subjected to intensive selection with attendant high population-wide linkage disequilibrium (LD). Presently, indigenous pig population with limited selection and low LD are being considered for improvement. Given that the infrastructure for genetic improvement using the conventional BLUP selection methods are lacking, a genome-wide selection (GS) program was proposed for developing countries. A simulation study was conducted to evaluate the option of using 60 K SNP panel and observed amount of LD in the exotic and indigenous pig populations. Several scenarios were evaluated including different size and structure of training and validation populations, different selection methods and long-term accuracy of GS in different population/breeding structures and traits. The training set included previously selected exotic population, unselected indigenous population and their crossbreds. Traits studied included number born alive (NBA), average daily gain (ADG) and back fat thickness (BFT). The ridge regression method was used to train the prediction model. The results showed that accuracies of genomic breeding values (GBVs) in the range of 0.30 (NBA) to 0.86 (BFT) in the validation population are expected if high density marker panels are utilized. The GS method improved accuracy of breeding values better than pedigree-based approach for traits with low heritability and in young animals with no performance data. Crossbred training population performed better than purebreds when validation was in populations with similar or a different structure as in the training set. Genome-wide selection holds promise for genetic improvement of pigs in the tropics.

Prevalence of Yersinia enterocolitica shedding and bioserotype distribution in Ontario finisher pig herds in 2001, 2002, and 2004

We investigated characteristics of Yersinia enterocolitica infection in Ontario finisher pig herds. Our specific objectives were to estimate or test: prevalence of Y. enterocolitica shedding in finisher pigs, bioserotype distribution, agreement between the herd-level tests based on sampling pig and pooled fecal samples, whether bioserotypes cluster by farms, and whether Y. enterocolitica-positive herds cluster spatially. In total, 3747 fecal samples were collected from 100 farms over the years 2001, 2002, and 2004 (250 total herd visits). Fecal samples were tested by culture and positive isolates were biotyped and serotyped. Apparent pig-level prevalence of Y. enterocolitica was 1.8%, 3.2%, and 12.5% in 2001, 2002, and 2004, respectively. Estimated true pig-level prevalence of Y. enterocolitica was 5.1%, 9.1%, and 35.1% in 2001, 2002, and 2004, respectively. Herd-level prevalence was 16.3%, 17.9%, and 37.5% in 2001, 2002, and 2004, respectively. In all years, the most common bioserotype was 4, O:3, followed by bioserotype 2, O:5,27. Kappa between herd-level status based on pig and pooled samples ranged between 0.51 and 0.68 for biotype 1A and bioserotype 4, O:3, respectively. For 4, O:3, a significant bias in discordant pairs was detected, indicating that pig samples were more sensitive than pooled samples in declaring a herd as positive. Farms tended to be repeatedly positive with the same bioserotype, but positive study farms did not cluster spatially (suggesting lack of between herd transmission and lack of a common geographic risk factor).

Effect of hCG treatment on the oestrous and ovulation responses to FSH in prepubertal gilts

To ensure sufficient numbers of pregnant females, particularly at hotter times of the year, hormonal induction of gilt oestrus may be necessary. However, the gilt oestrus and ovulation responses to gonadotrophin treatment have often proven unpredictable. The objective of this study was to examine possible reasons for this unpredictability. Prepubertal gilts (approximately 150 days of age, n = 63) were assigned to one of three treatments: injection of 300 IU hCG (n = 15); pre-treatment with 100 mg FSH in polyvinylpyrrolidinone administered as 2 x 50 mg injections 24 h apart, followed by 600 IU eCG at 24 h after the second FSH injection (n = 23); or FSH pre-treatment as above followed by 300 IU hCG at 24 h after the second FSH injection (n = 25). To facilitate oestrus detection, gilts were exposed to a mature boar for 15 min daily for 7 days. Blood samples were obtained on the day of eCG or hCG injection and again 10 days later and gilt ovulation responses determined based on elevated progesterone concentrations. The oestrus responses by 7 days were 6.7%, 17.5% and 64.0% for gilts treated with hCG, FSH + eCG and FSH + hCG, respectively (p < 0.001). The oestrous gilt receiving hCG alone and one oestrous FSH + hCG gilt did not ovulate, all other oestrous gilts ovulated. A further two anoestrous FSH + eCG-treated gilts ovulated. These data suggest that FSH pre-treatment facilitated the development of ovarian follicles to the point where they became responsive to hCG, but had little effect on the response to eCG.

Effect of prior FSH treatment on the estrus and ovulation responses to eCG in prepubertal gilts

The objective of this study was to determine the effect of pre-treatment of prepubertal gilts with FSH on the estrus and ovulatory responses to eCG injection at two ages. A total of 149 prepubertal Hypor gilts were selected at 150 days (n=76) or 180 days (n=73) of age and assigned to injection of 400 IU eCG plus 200 IU hCG (PG600), 600IU eCG alone (Folligon), pre-treatment with 72 mg FSH (Folltropin) administered as 6 x 12 mg injections at 12 h intervals with 600 IU Folligon 12h after last FSH injection, or non-injected controls. To facilitate detection of estrus, gilts were exposed to a mature boar for 15 min daily for 7 days. To determine ovulatory responses, blood samples were obtained on the day of injection and 10 days later and assayed for progesterone content. Following treatment at 150 days, one control gilt (5.3%) was deemed estrus but ovulation did not occur. Compared to treatment with Folligon alone, PG600 injection tended (P=0.1) to increase the estrus response (52.6% compared with. 26.3%) and increased (P<0.01) the ovulatory response (89.5% compared with. 47.4%). The estrous response in gilts pretreated with Folltropin was intermediate (42.1%) but the ovulatory response (47.4%) was the same as for Folligon alone. Following treatment at 180 days, two control gilts (10.5%) were deemed estrus and ovulation did occur in these gilts. There was no difference between hormone-treated groups for estrus or ovulatory responses, although the ovulatory response of PG600-treated gilts tended (P=0.1) to be greater than for the Folligon-treated group (89.5% compared with 66.7%), with Folltropin-pretreated gilts being intermediate (76.5%). These data demonstrate that the estrus and ovulatory responses of gilts were greater for PG600 than for Folligon and that while responses to PG600 were not affected by gilt age, for the combined Folligon groups, estrous response (P<0.02) and ovulatory response (P<0.05) improved with increased gilt age.

Effect of insemination-ovulation interval and addition of seminal plasma on sow fertility to insemination of cryopreserved sperm

In swine, the use of frozen-thawed (FT) sperm for artificial insemination (AI) is limited because of poor sow fertility, possibly associated with a post-thaw capacitation-like status resulting in fewer fully viable sperm. Sow fertility to AI with FT sperm may improve with deeper deposition of sperm within the female tract, insemination very close to ovulation, or reversal of cryocapacitation by seminal plasma (SP). We performed two experiments to examine these suggestions. In experiment 1, 122 multiparous Yorkshire sows received 600 IU equine chorionic gonadotrophin at weaning and 5 mg pLH 80 h later to control time of ovulation. The predicted time of ovulation (PTO) was 38 h after pLH injection. Thereafter, sows were assigned on the basis of parity to a single AI of FT sperm at 2 h before PTO, or at 12 h before PTO, or FT sperm supplemented with 10% SP at 12 h before PTO. Control sows received fresh semen at 12 h before PTO. All semen doses were adjusted to 3 x 10(9) live cells and deposited into the cervix. Experiment 2 employed 99 multiparous crossbred sows and repeated the treatments of experiment 1 except that all FT inseminations were intrauterine. In both experiments, farrowing rates were lower (p < 0.01) following FT inseminations with no effect of time of insemination or of supplemental SP. In experiment 1, litter size was smaller following FT insemination (p < 0.05), but no effect on litter size was evident in experiment 2. Supplemental SP had no effect on litter size in either experiment. The lack of effect of either SP or timing of FT insemination on sow fertility suggests that the non-lethal sperm cryoinjury affecting fertility involves more than just cryocapacitation.

In vitro assessment of antimicrobial activity of carvacrol, thymol and cinnamaldehyde towards Salmonella serotype Typhimurium DT104: effects of pig diets and emulsification in hydrocolloids

AIMS

To determine the effect of pig diets in vitro on the antimicrobial activity of carvacrol, thymol and cinnamaldehyde, and to identify an emulsifier/stabilizer that can stabilize the essential oil (EO) components in aqueous solution and retain their antimicrobial activity in the presence of the diets.

METHODS AND RESULTS

Emulsification of essential oil components with hydrocolloid solution was achieved by blending with a Polytron. Antimicrobial activity was measured through in vitro assays to determine the inhibition of bacterial growth by measuring the optical density at 600 nm or plating on nutrition agar after incubation of the mixtures of an EO component with the culture of Salmonella serotype Typhimurium DT104 in the presence or absence of pig diets. The results generated through the in vitro assays indicated that pig diets were able to abolish the antimicrobial activity of EOs. Xanthan, fenugreek and yellow mustard gums were the best in forming stable emulsions of five different EO components among ten different plant polysaccharides and surfactants examined. Emulsification of all the EO components in the fenugreek gum solution did not alter their antimicrobial activity. However, the antimicrobial activity of geraniol was significantly reduced when emulsified with other polysaccharides and surfactants. Both fenugreek and xanthan gum solutions were unable to protect the antimicrobial activity of carvacrol and thymol when mixed with the diets. Although cinnamaldehyde required no emulsification, but a high concentration (equivalent to at least three times of minimum bactericidal concentration for cinnamon oil) to inhibit Salmonella growth significantly in the presence of the diets, emulsification in fenugreek gum appeared to be essential for cinnamaldehyde solution to retain its antimicrobial activity during storage.

CONCLUSIONS

The diets for newly weaned pigs were a significant factor limiting the antimicrobial activity of EOs and their components. Cinnamaldehyde required a high concentration to retain its antimicrobial activity in the diets, in addition to its requirement for emulsification to stabilize its activity during the storage.

SIGNIFICANCE AND IMPACT OF THE STUDY

The assay with the diets used in this study for measuring the antimicrobial activity can be used in vitro for rapid and effective screening of potential antimicrobials for swine production. This study has identified polysaccharides that are able to stabilize EO component solutions. It has also identified cinnamaldehyde for further in vivo studies that may have potential in future application in controlling Salmonella and possibly other enteric pathogens in swine production.

Effect of sperm cryopreservation and supplementing semen doses with seminal plasma on the establishment of a sperm reservoir in gilts

Frozen-thawed (FT) boar sperm have a reduced fertile life, due in part to a capacitation-like status induced by cooling. Reversal of this cryocapacitation in vitro by exposure to boar seminal plasma (SP) has been demonstrated. The objective of these studies was to determine the effect of SP on the ability of FT sperm to create an oviductal sperm reservoir following artificial insemination (AI). In Experiment one, 35 pre-pubertal gilts were injected (IM) with 400 IU eCG plus 200 IU hCG to induce oestrus. At detection of oestrus, gilts were inseminated with 3 x 10(9) live sperm, either fresh (FS; n = 13), FT (n = 10), or FT supplemented with 10% v/v SP (n = 12). Gilts were killed 8 h later, their reproductive tracts recovered and the uterotubal junctions (UTJs) flushed to recover sperm. Fewer (p < 0.01) sperm were recovered following FT, compared to FS, inseminations, and there was no evident effect of SP. In Experiment two, 30 pre-pubertal gilts received IM injections of 1000 IU eCG followed by 5 mg pLH 80 h later to control time of ovulation. Gilts were inseminated with 3 x 10(9) live FS sperm (n = 6), FT sperm (n = 15) or FT sperm plus 10% SP (n = 9) at 12 h before ovulation and then sacrificed 8 h later. The UTJs were dissected and flushed for sperm recovery. Fewest (p < 0.001) sperm were recovered following FT insemination and there was no evident effect of SP. These data demonstrate that the size of the sperm reservoir is markedly reduced in gilts inseminated with FT sperm. However, the lack of effect of SP suggested that either it did not reverse cryocapacitation or that such a reversal does not impact the in vivo ability to create a sperm reservoir.

Effects of boar presence on agonistic behavior, shoulder scratches, and stress response of bred sows at mixing

The objective of this study was to determine the effects of boar presence on aggression, shoulder scratches, and salivary cortisol in group-housed sows during the period after mixing, which is when dominance hierarchies are formed. A total of 225 York-shire sows were used. Five groups of 15 sows were each exposed to 1 of 3 levels of boar presence (n = 15): physical (boar in pen with sows; 2.15 m2 per sow), fenceline (boar housed adjacent to sows; 2.3 m2 per sow), or control (no boar in the room; 2.3 m2 per sow). The experiment was divided into 2 phases. In phase 1, behavioral measurements were taken for 48 h after mixing and boar introduction. In phase 2, behavioral measurements were taken beginning on d 6 after mixing and included 24 h before and 48 h after boar removal. In phases 1 and 2, shoulder scratches were scored 24 h before and 24 h after mixing and boar removal, respectively. Saliva samples were collected each morning (0600 to 0700) and afternoon (1600 to 1700) during both phases. Frequencies of intersow aggressive contact (bite, body knock, and head knock) and threats as well as frequencies and durations of fighting bouts were determined from video recordings during daily feeding (49.6 +/- 1.4 min) and nonfeeding (21 +/- 0.2 h) periods. During phase 1, boar presence did not affect the frequency of threats during either the feeding or nonfeeding periods. Control groups had fewer aggressive contacts at feeding during the 25- to 48-h period compared with the fenceline groups (P = 0.01). Total duration of fighting and average fighting bout duration were unaffected by treatment. However, the number of fights occurring during feeding 25 to 48 h postmixing was lower in the physical groups than in the fenceline groups (P = 0.023); measures for the control groups were intermediate. Physical sows also received fewer shoulder scratches postmixing than did control sows (P = 0.048). After mixing, physical sows showed greater morning (P = 0.08) and afternoon (6 h postmixing, P = 0.01; 32 h postmixing, P = 0.08) salivary cortisol concentrations compared with fenceline sows, although they were only numerically greater than those for control sows. During phase 2, removing the boar did not increase fighting among sows or affect shoulder scratches or salivary cortisol concentrations. The presence of a boar was minimally effective at reducing fighting and scratches during the postmixing period, and sows showed a greater stress response in the presence of a boar.

Evaluation of enzyme-linked immunosorbent assay (ELISA) tests and culture for determining Salmonella status of a pig herd

The purpose of this study was to evaluate Salmonella ELISA tests and a culture technique to determine Salmonella status using samples collected from commercial herds. Faecal samples from 15 finisher pigs on each of 40 swine farms were cultured for Salmonella. Sera from the same 600 pigs were analysed for the presence of antibodies to Salmonella by means of two different ELISA kits Salmotype (Salmotype Labordiagnostik, Leipzig, Germany) and IDEXX (Herdchek* Salmonella; IDEXX Laboratories, Schiphol-Rijk, Noord-Holland, The Netherlands). The Salmotype ELISA test demonstrated a moderate ability to differentiate culture-positive pigs from culture-negative pigs while IDEXX was relatively poor in classifying those pigs correctly (The area under the curves were 0.79 and 0.65 for Salmotype and IDEXX respectively). The maximum value of sensitivity plus specificity was gained at the cut-off optical density (OD) > or =25% for Salmotype (sensitivity 0.65, specificity 0.84) and at the OD > or =9% for IDEXX (sensitivity 0.59, specificity 0.69). The maximum herd sensitivity and herd specificity was 0.64 (95% CI 0.49-0.79) and 0.72 (95% CI 0.59-0.86) for the Salmotype test and 0.73 (95% CI 0.59-0.87) and 0.62 (95% CI 0.47-0.77) for the IDEXX. Culture and the ELISA tests showed fair agreement at the herd level (kappa=0.3, P<0.05). Likewise there was significant disagreement between the two ELISA tests at the pig level, but very good agreement between the two ELISA tests (kappa=0.8, P<0.0001) at the herd level. The coating antigens in Salmotype and IDEXX represent only 48% of the antigens of Salmonella isolated in our study and need to be revised based upon the Salmonella serovar distribution in Ontario.

Prevalence of hepatitis E virus antibodies in Canadian swine herds and identification of a novel variant of swine hepatitis E virus

Swine hepatitis E virus is a newly identified potentially zoonotic virus from pigs of particular concern for possible direct transmission to a human xenotransplant recipient by organ transplantation. In the present study, prevalence of serum antibodies to hepatitis E virus was examined in Canadian swine herds. A total of 998 serum samples collected from 6-month-old healthy slaughter hogs were examined by enzyme immunoassay and Western blot analysis for antibodies to the recombinant open reading frame 3 (ORF3) protein of hepatitis E virus expressed in Escherichia coli. These samples represented more than 80 different swine production units from five major swine-producing provinces across Canada. From this study, 594 samples (59.4%) were found to be positive for hepatitis E virus antibody. The seroprevalence was higher in Quebec (88.8%) and Ontario (80.1%) than in Alberta and Saskatchewan (38.3%). By PCR using a pair of oligonucleotide primers deduced from the ORF2 sequence of human hepatitis E virus, a specific hepatitis E virus sequence was recovered from feces of pigs. The nucleotide sequence identity between the U.S. swine hepatitis E virus and the Canadian isolate (SK3) was only 85.8%, suggesting that genotypic variations may exist in swine hepatitis E virus in North America. Among 165 serum samples collected from humans in Saskatchewan, 2.4% were found to be positive for antibodies to the hepatitis E virus ORF3 protein. Our data indicate that hepatitis E virus is highly prevalent in commercial swine populations in Canada and support the suggestion that the swine hepatitis E virus may be an important zoonotic agent for humans.

Effect of health management strategy during rearing on grower-finisher pig performance and selected indicators of immune system stimulation

The effects of health management strategy during rearing on subsequent growth performance and indicators of immune system stimulation in grower-finisher (G-F) pigs were evaluated. Pigs of approximately 25 kg body weight (BW) were sourced from three different management systems: (1) a farrow-to-finish unit with identified respiratory problems (Conventional), (2) segregated early weaned (SEW; piglets sourced from multiple sow herds), and (3) a minimal disease farrow-to-finish operation (MD). The pigs were of similar genetic background and were housed under similar conditions until slaughter. During the grower phase, MD had the highest average daily gain (ADG) (P < 0.05), while it was similar for SEW and Conventional (P > 0.10). Feed to gain (F:G) was similar for MD and SEW (P > 0.10), and poorest for Conventional (P < 0.05). During the finisher phase, SEW had the lowest ADG, and the poorest F:G (P < 0.05); these parameters were similar for Conventional and MD (P > 0.10). Over the entire G-F period, performance of MD pigs was better than that of Conventional and SEW pigs. Performance depressions appeared related to the degree of anterior-ventral lung atelectasis, antibody titers to porcine reproductive and respiratory syndrome (PRRS) virus and Mycoplasma hyopneumoniae, thymus size, plasma insulin-like growth factor levels, stomach ulceration, nasal turbinate damage, and microbial burden. The current study shows that the growth depressing effects of exposure to infectious organisms can be substantial in G-F pigs. Key words: Pigs, growth performance, disease, cytokines

An investigation of the etiology of a mild diarrhea observed in a group of grower/finisher pigs

An investigation into a mild diarrhea in a group of grower/finisher pigs was carried out in order to determine the etiology. A tiamulin injection and a carbadox-medicated ration were given to pens of pigs in a 2 x 2 factorial experimental design. Pens of pigs were assessed a score, based on the consistency of the feces in the pen, each week. The clinical investigation looked for the intestinal pathogens Brachyspira pilosicoli, B. hyodysenteriae, Lawsonia intracellularis, Salmonella spp., Yersinia spp., transmissible gastroenteritis virus, and rotavirus. Despite a rigorous investigation, the diarrhea was not attributed to any pathogen. A mild colitis was noted among pigs necropsied while affected with diarrhea. Improved diagnostic tools may allow a more effective response to an outbreak of mild disease, while at the same time reducing the amount of antimicrobials used in swine production.

The use of omeprazole to alleviate stomach ulcers in swine during periods of feed withdrawal

Controlled trials were conducted to determine if treatment with the benzimidazole compound, omeprazole, would prevent gastric ulceration associated with feed withdrawal. Pigs were fed ad libitum, fasted for 24 h, or fasted for 48 h, and within each of these 3 groups the effect of no medication (controls), of 20 mg or 40 mg of omeprazole was evaluated on the pH of gastric fluid and the presence or absence of lesions in the pars esophagea. Medication with 40 mg of omeprazole resulted in significantly higher gastric pH 24 h after treatment compared with untreated pigs or pigs medicated with 20 mg of omeprazole. Fasting for 24 h or for 48 h, resulted in more pigs developing ulcers (15 of 25) than pigs allowed free access to feed (1 out of 10) (P = 0.01). The results of this trial suggest that omeprazole was effective in preventing some, but not all, of the tissue damage in the pars esophagea related to feed withdrawal. In addition to hydrochloric acid, possibly other components, such as bile acids in the fluid gastric contents, are important in causing epithelial injury.

Circadian variation of portal, arterial and venous blood levels of melatonin in pigs and its relationship to food intake and sleep

Circadian levels of melatonin were determined in the hepatic portal vein, cranial vena cava, and the lower aorta of ten juvenile pigs. Blood was sampled every hour for a total of 24 hr via temporary cannulas introduced into blood vessels under anesthesia. No peak levels of melatonin were found in the mid-scotophase, but hepatic portal concentrations peaked at 06.00 hr. Overall levels of melatonin were highest in the hepatic portal vein (range 35-65 pg/mL), followed by an artery (range 30-55 pg/mL) and the vena cava (range 25-35 pg/mL). Levels of melatonin exhibit strong variation between individual pigs, but generally the average levels from all three sources follow each other's time course. However, on occasion, melatonin levels in the hepatic portal vein varied independently from the levels in the vena cava. Large portal peaks were usually preceded by a feeding period and were associated with a subsequent period of sleep. The data indicate that: 1) there is no clear circadian rhythm of melatonin in the peripheral blood of pigs, 2) relatively little melatonin is metabolized during the first liver passage, 3) food intake may elevate melatonin levels in the hepatic portal vein, and 4) increased levels of melatonin originated in the gastrointestinal tract may induce sleep.

Evaluation of lansoprazole (an H+/K+-ATPase inhibitor) and azithromycin (an antibiotic) for control of gastric ulceration in swine during periods of feed deprivation

Helicobacter-like organisms as well as fermentative bacteria have been implicated in gastric ulcer production in swine. Irregular feeding schedules are also considered a major risk factor. A research trial was conducted to determine whether medication with an acid secretion inhibitor (lansoprazole), either alone or in combination with an antibiotic (azithromycin), would protect pigs from gastric ulceration if the animals were subjected to a 48 h period of fasting. In a 2 x 3 factorial design, 48 pigs were fasted, while an equal number were fed ad libitum. Within these 2 study groups, pigs were randomly assigned to 1 of 3 treatments: control, 30 mg lansoprazole s.i.d. for 7 d, or lansoprazole (30 mg s.i.d. for 7 d) and azithromycin (500 mg s.i.d. for 3 d). Overall, fasted pigs were 1.9 times more likely to develop erosive or ulcerative lesions of the pars esophagea (chi2 = 9.89, P < 0.002). Treatment with an acid secretion inhibitor alone or in combination with an antibiotic did not protect pigs from developing gastric lesions. Helicobacter-like organisms were not detected in any of the stomachs. Possibly, the lansoprazole dose of 30 mg given once per day was insufficient to prevent pH levels from becoming low enough to cause damage to epithelial tissue. Alternatively other substances such as bile acids may have caused the ulcerative lesions, even though stomach acid production was suppressed.

Sampling considerations for herd-level measurement of faecal Escherichia coli antimicrobial resistance in finisher pigs

The objective of this study was to determine the most efficient means of sampling faeces of finisher pigs for accurate and precise farm-level estimates of antimicrobial resistance among faecal Escherichia coli. Resistance to tetracycline and gentamicin of 8250 isolates of E. coli from 55 finisher pigs on one farm was measured with a hydrophobic grid membrane filter method. The between-pig, within-pen component of variance in resistance was large (97.5%), while between-pen, within-room and between-room components were small (2.5% and 0%, respectively). Using these resistance data, the abilities of two sampling strategies to estimate prevalence were modelled with a Monte Carlo 'bootstrap' procedure. Compositing faecal samples from several pigs before testing produced unbiased and precise estimates of prevalence and is simpler technically than individual animal testing.

Effect of feed particle size and dietary melatonin supplementation on gastric ulcers in swine

Gastric ulcers may be an underrecognized problem in the swine industry. An experiment was conducted to evaluate the effects of dietary melatonin supplementation and particle size on prevalence and severity of ulcers in growing pigs. Sixty-four Yorkshire barrows and gilts (29.5 ± 1.0 kg) received either a finely ground (763 ± 2.18 µm) or a coarsely ground (953 ± 2.29 µm) corn–wheat diet, either with or without added melatonin (5 mg kg−1). One half of the pigs underwent endoscopic examination to assess the severity of ulcers on days 4 and 25. Growth performance and feed consumption were monitored throughout the experiment. All pigs were slaughtered on day 28, and ulcers were assessed postmortem. Endoscopy at the beginning of the experiment found that 53% of the pigs already had some degree of ulceration. Pigs fed the fine diet had greater average daily gain and average daily feed intake than pigs fed the coarse diet (P < 0.05), but particle size did not significantly affect prevalence of stomach ulcers. Melatonin supplementation increased the apparent digestibility of crude protein (P < 0.04) and dry matter (P < 0.08) of the diets and decreased the prevalence of ulcers (P < 0.05) but did not significantly affect growth performance. Pigs that received melatonin had higher levels of melatonin (P < 0.01) in most gastrointestinal tissues, with highest concentrations found in the stomach (P < 0.001). Pigs that did not have ulcers had a higher concentration of melatonin in the plasma and stomach than pigs with ulcers (P < 0.05). Melatonin may be useful in decreasing ulcers. Initial ulcer condition may be a significant source of variation in growth experiments. Key words: Pigs, gastric ulcers, particle size, melatonin, gastrointestinal tract

The effect of the Hurnik-Morris (HM) system on sow reproduction, attrition, and longevity

Sows were randomly selected and assigned to either the Hurnik-Morris system (HM; n = 59) or a conventional gestation crate system (GC; n = 90) before breeding. The HM system provides housing for sows in small groups. All sows were bred to Duroc x Hampshire commercial boars. A common farrowing barn with 18 farrowing crates was used for the HM and GC sows. The HM sows had less (P<.001) backfat at farrowing. Average parity per sow (P<.046), lifetime number of pigs born per sow (P<.02), lifetime number of pigs born alive per sow (P<.02), and lifetime number weaned per sow (P<.045) were higher for sows housed in the HM system. The total number of sows removed from the GC system was higher (P<.025) than the number leaving the HM system. The higher parity level and lifetime production exhibited by the sows in the HM system indicates that this system supports greater longevity and may reflect the superior effect that this housing system has on animal well-being.

Individual and group antimicrobial usage rates on 34 farrow-to-finish swine farms in Ontario, Canada

Antimicrobial drug-use was assessed on 34 farrow-to-finish operations that marketed at least 500 hogs/yr. These operations either did not use any antimicrobials or used narrow-spectrum or broad-spectrum antimicrobials in rations of post-weaning pigs. Total antimicrobial use was measured for two months after obtaining inventories and records of all antimicrobials used. The collection of empty medication bottles and inventories of drugs on hand was convenient for producers and useful for estimating or validating recorded treatment rates, particularly for antimicrobials that were used only in one class of pig. Treatment records, however, underestimated by approximately 35% the amounts used for 27/29 farm-antimicrobial combinations. Rates of individual-pig treatment varied from 0-24.1 pigs treated/1000 pig-days, with a median of 5.29. Most individual animal treatments were given to piglets and sows at parturition and penicillin was the most commonly used antimicrobial. Gentamicin was administered to suckling piglets on 19 of the farms.

Associations among antimicrobial drug treatments and antimicrobial resistance of fecal Escherichia coli of swine on 34 farrow-to-finish farms in Ontario, Canada

Logistic regression was used to model associations between antimicrobial treatment and resistance among fecal Escherichia coli of finisher pigs at the farm level. Four sets of potential risk factors representing different levels of refinement of antimicrobial use on farms were modelled on resistance to antimicrobials. Final models for each antimicrobial were constructed from treatment and management variables significant on initial screening, and corrections for overdispersion were made. In general, in-feed antimicrobial treatment of pigs was more consistently associated with an increased risk of resistance than individual-animal treatment. Antimicrobial treatment in starter rations was significant in final models of resistance to ampicillin, carbadox, nitrofurantoin, sulfisoxizole, and tetracycline. Treatment in grower-finisher rations was significantly associated with resistance to ampicillin, spectinomycin, sulfisoxizole, and tetracycline. There was little evidence that in-feed antimicrobials increased the risk of resistance to gentamicin, which is a drug used only for individual-pig treatment in this study population. These results suggest that antimicrobial medication of rations of post-weaning pigs selects for and maintains antimicrobial resistance among E. coli of finisher pigs. Although resistance was common on farms that did not medicate rations of post-weaning pigs, the results indicate that antimicrobial use does increase the risk of resistance to the antimicrobials studied.

Prevalences of resistance to seven antimicrobials among fecal Escherichia coli of swine on thirty-four farrow-to-finish farms in Ontario, Canada

Fecal specimens were composited and a hydrophobic-grid membrane-filter method was used to measure antimicrobial resistance to ampicillin 16 micrograms/ml, carbadox 30 micrograms/ml, gentamicin 4 mu/ml, nitrofurantoin 32 micrograms/ml, spectinomycin 16 micrograms/ml, sulfisoxazole 32 micrograms/ml and tetracycline 8 micrograms/ml among 8119 Escherichia coli isolates from 68 fecal samples collected on 34 farrow-to-finish swine farms marketing over 500 hogs/yr. The overall prevalences of resistance to antimicrobials among these isolates were: ampicillin 29%, carbadox 3.5%, gentamicin 0.6%, nitrofurantoin 27%, spectinomycin 28%, sulfasoxizole 38% and tetracycline 71%. Thirty to seventy-six per cent of the variations in prevalences were explained by between-farm differences.

Relationship between melatonin levels in plasma and gastrointestinal tissues and the incidence and severity of gastric ulcers in pigs

Four weeks of administration of melatonin mixed in the diet (5 mg/kg of food) significantly reduced the incidence of gastric ulcers in young pigs. In control and melatonin supplemented animals, significantly higher levels of melatonin were found in the stomach tissues as compared to jejunum, ileum, or colon. Pigs with the most severe ulcers exhibited significantly lower concentrations of melatonin in their stomach tissue and the blood plasma. Pigs fed coarsely ground diet exhibited higher tissue levels of melatonin in the stomach than animals fed a finely ground diet. Coarse diet was also associated with a lower score of gastric ulcers. No relationship between tissue levels of melatonin and the severity of gastric ulcers was found in other segments of the gastrointestinal tract. In the second experiment we determined that there was no significant difference between the gastro-protective effects of 2.5, 5.0, and 10.0 mg of melatonin mixed per 1 kg of food. A coarsely ground diet is hypothesized to have a gastro-protective effect by stimulating the production of melatonin in the stomach tissues. Dietary supplementation of food with melatonin, at threshold levels perhaps lower than 2.5 mg/kg/feed, may significantly reduce the incidence of gastric ulcers in pigs.

Measurement of antimicrobial-resistant Escherichia coli in pig feces with a hydrophobic grid membrane filter interpreter system

Hydrophobic grid membrane filter technology was used to measure resistance among Escherichia coli in pig fecal samples to ampicillin, sulfisoxazole, and tetracycline. The method accurately measured resistance, with sensitivities ranging from 96.5 to 99.5% and specificities ranging from 87.0 to 98.3%, and it identified E. coli with 96% confidence.

Effects of castration on early postnatal development of male accessory sex glands in the domestic pig

In the neonatal pig there is a remarkable production of steroids by the testes for the first few weeks after birth. Several androgens and estrogens reach a peak at about one month of age. In order to gain an understanding of the significance of this early steroid secretion we examined the effect on accessory sex glands of removal of the testes before the peak in these compounds would have occurred. Pigs were castrated (n = 38) at 2-3 weeks of age, with littermates serving as intact controls (n = 33). Animals were killed at ages ranging from 4-12 weeks. Blood samples were taken and both bulbourethral (BU) and vesicular glands (VG) were removed, as well as the testes of intact males. Organ pairs were weighted and samples fixed for histological examination. Plasma samples were stored at -20 degrees C until assayed, without extraction, for testosterone, dehydroepiandrosterone sulfate (DHEAS) and estrone sulfate (E1S) by radioimmunoassay. Of the hormones measured, plasma DHEAS concentrations were highest, but variable over the time period (304.2 and 75.6 nmol/l; 87.7 and 21.8 ng/ml at 5 and 12 weeks respectively). E1S declined steadily from 76.6 to 5.8 nmol/l (20.7 to 1.56 ng/ml). Testosterone levels were lowest but rose from 2.67 to 9.54 nmol/l (0.77 to 2.75 ng/ml). No steroids were clearly detectable in samples from castrated males. Testes weights (wt) increased fourfold, as did body wt for both intact and castrate males. Both BU and VG showed absolute increase in wt (3.5x and 5x respectively) in intact males, and each was about 2.8x greater than in castrates (mg/kg body wt). Histological sections were markedly distinctive for both BU and VG between intact and castrate animals, and a lack of developmental changes in both glands was noted in the castrates. Our findings provide clear evidence of an influence of the testes on accessory sex glands in the early postnatal life of the pig.

Development and evaluation of an endoscopic technique permitting rapid visualization of the cardiac region of the porcine stomach

Our study was designed to ascertain whether a flexible videoscope could be used to efficiently monitor ulcers of the pars esophagea in a large group of grower-finisher swine. Gastroscopy was performed on 2 separate occasions in 32 pigs following anesthesia with intravenous pentobarbital, and ulcers of the pars esophagea were subjectively graded. The pigs were then necropsied. Grades from the second endoscopic examination were compared for agreement with grades derived from gross inspection of the pars esophagea at necropsy, and with grades derived from histopathologic examination of sections of the same region. The pars esophagea was adequately visualized in all endoscopic examinations. The average duration of each examination, from anesthetic induction, was approximately 8 min. Gastroscopy permitted appreciation of a wide range of focal and diffuse superficial and deep ulcerative lesions of the pars esophagea, but failed to unequivocally identify parakeratosis of the pars esophagea. Agreement between endoscopic and subsequent necroscopic and histopathologic gradings of ulcerations was poor. We concluded that the use of a flexible videoscope permitted rapid inspection of the pars esophagea, and was therefore a practical method of experimentally monitoring the progression of spontaneous gastric ulcers in pigs. We also postulated that the poor agreement between endoscopic and postmortem findings occurred because endoscopy was possibly more sensitive at detecting small and superficial ulcerations. However, further studies are needed to verify the accuracy of endoscopic diagnosis of gastric ulcers in the live pig.

The effects of feeding a chocolate product on growth performance and meat quality of finishing swine

The effects of including a waste chocolate confectionary product in swine diets on growth performance, carcass composition and meat quality of finishing pigs were determined. Four isocaloric, isonitrogenous diets were formulated to include 0, 10, 20 and 30% of a chocolate product in a pelleted corn and soybean-meal-based-diet and fed ad libitum to 32 gilts and 32 barrows from 54 kg to 105 kg. There were no significant differences among diets for average daily gain, feed intake and feed efficiency. Fat content in the diets increased from 3 to 7% with increasing inclusion, but there were no significant (P > 0.05) differences for backfat depth, total dissected fat, total lean or percent lean of the dissected carcass. With respect to meat quality, there were no significant differences observed for colour, structure and marbling of the loin and ham muscle. There were no treatment differences for the firmness of the inner backfat of pigs consuming the various diets. Waste chocolate confectionary can be fed to growing swine at inclusion levels up to 30% of the diet with no adverse effects on growth or carcass quality. Key words: Alternative feedstuff, chocolate, pigs, growth performance, carcass quality

The effect of the Hurnik-Morris (HM) system on sow locomotion, skin integrity, and litter health

Gilts (n = 187) were randomly assigned to either the Hurnik-Morris housing system (HM) or a conventional gestation crate system (GC) prior to breeding. The Hurnik-Morris system provides housing for sows in small groups. Gilts were synchronized for estrus and bred to Duroc Hampshire commercial crossbred boars. Gilts were reared in their respective housing systems through their gestation period. Housing system during breeding and gestation of sows did not affect their respective piglet mortality and piglet viability levels. The slightly higher feet and leg problem scores for the HM sows at weaning may indicate a necessity for farrowing accommodation that will allow movement of sows during lactation.

The effect of graded levels of melatonin on performance and gastric ulcers in pigs

Graded concentrations of dietary melatonin were fed to examine the effects on performance and gastric ulcers in pigs. Four levels of melatonin, 0, 2.5, 5, and 10 mg kg−1, were fed m a finely ground corn–wheat based diet (578 ± 1.89 μm), designed to induce gastric ulcers, to 64 Yorkshire barrows and gilts between 22.2 ± 2.0 and 102.5 ± 4.3 kg. At postmortem, ulcers were scored from 0 (no ulcer) to 3 (severe ulcer). Volume, percent moisture, pH, and bile acid concentration of the stomach digesta were determined. Melatonin supplementation was associated with a decreasing severity of ulcers (P < 0.05). There were no differences in average daily gain between melatonin treatments, although 10 mg kg−1 diet caused a reduction in feed intake. Bile acid concentration in the stomach digesta was highest in pigs receiving the control diet without melatonin (P < 0.05) and was increased with increasing ulcer severity (P < 0.05). Key words: Swine, ulcer, diet, melatonin, bile, acids

Return to oestrus after first insemination in sow herds (incidence, seasonality, and association with reproductivity and some blood parameters)

As no systematic study has been done to get an accurate estimate of the incidence of return to oestrus after first insemination in sows in the Netherlands, the objectives of this investigation were: 1) to obtain an estimate of the incidence of return to oestrus after insemination at the herd level; 2) to investigate the association between incidence of return to oestrus after first insemination and reproduction characteristics in order to get an impression of the economic importance of reproductive failure. These objectives were investigated by using the reproduction results of 240 swine breeding herds in the Southern Netherlands in 1987. This information was obtained from CBK plus computerized herd management records. The average incidence rate of return to oestrus after first insemination at a herd level was 16.9 per 100 first inseminations. The occurrence of return to oestrus after first insemination was distinctly higher in the insemination months July and August compared to the rest of the year. An increased incidence, with 10 returns per 100 first inseminations corrected for confounders in a multiple linear regression model, was associated with a decrease of approximately 0.3 live born piglets/sow/year. A prospective longitudinal study was started in 1988 and 1989 in 37 sow herds. Individual sows were monitored from weaning to first insemination, to the occurrence of return to oestrus, or not, after first insemination, and to farrowing. The investigation focused in particular on the relationship between return to oestrus after first insemination and seroconversion against porcine parvovirus (PPV) and Leptospira interrogans serovar bratislava (L. bratislava).(ABSTRACT TRUNCATED AT 250 WORDS)

[Return to estrus following first insemination in sow herds (incidence and association with reproductivity and various blood parameters)]

As no systematic study has been done to get an accurate estimate of the incidence of return to oestrus after first insemination in sows in the Netherlands, the objectives of this investigation were: 1) to obtain an estimate of the incidence of return to oestrus after insemination at the herd level; 2) to investigate the association between incidence of return to oestrus after first insemination and reproduction characteristics to get an impression of the economic importance. These objectives were investigated using the reproduction results of 240 swine breeding herds in The Southern Netherlands in 1987, using their CBK plus computerized herd management records. The average incidence of return to oestrus after first insemination on a herd level was 16.9 per 100 first inseminations. An increase of incidence with 10 returns per 100 first inseminations, corrected for confounders in a multiple linear regression model, was associated with a decrease of approximately 0.3 liveborn piglets/sow/year. Thereupon individual sows were followed in 1988 and 1989 prospectively in 37 sow herds from weaning to insemination, returning to oestrus or not after first insemination to farrowing. The investigation focused in particular on the relationship between returning to oestrus after first insemination and incident infection with porcine parvovirus (PPV) and Leptospira interrogans serovar bratislava (L. bratislava). During a number of consecutive farm visits sows were blood sampled at weaning and again a blood sample was taken 6 weeks later. The final dataset that was analysed consisted of 161 animals that did not return to oestrus after first insemination and 158 animals that returned to oestrus after first insemination.(ABSTRACT TRUNCATED AT 250 WORDS)

The behavior of gestating swine housed in the Hurnik-Morris system

A group housing system for sows, the Hurnik-Morris (HM) system, was developed to address several of the perceived animal welfare limitations of existing housing methods. The HM system permits socially coordinated eating and resting, controlled and socially undisturbed feed intake, physical exercise, and regular exposure to boars. The HM system effectively uses and reinforces the behavioral phenomenon of the social synchronization of feeding and provides a less restrictive housing environment. The system provides housing for sows in small groups and an individual, non-competitive feeding environment using electronic feeding compartments. Gilts reared during gestation in the HM system were observed to spend less time lying in sternal recumbency (31 vs 21%; P = .004) and performing stereotypies (.10 vs .56%; P = .034) and to spend more time participating in social activities (1.4 vs .19%; P = .0007) than similar gilts kept in gestation crates (GC). The HM sows revealed a significantly longer latent period to postprandial lying than did GC gilts (64 vs 32 min; P = .0001). The order of gilt entry into the feeding compartments tended to be more consistent than the sequence of feeding compartments being entered (W = .57 vs .41; P = .06). This indicates that social factors seemed to be more important than spatial ones in determining the order of entry into the feeder compartments.

Secretion of 19-hydroxyandrostenedione and 19-hydroxytestosterone by porcine Leydig cells in vitro and in vivo

19-Hydroxytestosterone and 19-hydroxyandrostenedione have been identified as secretory products of the testes in the mature male domestic pig. Their isolation and identification were made by reverse-phase high-performance liquid chromatography and capillary gas chromatography-mass spectrometry (CGC-MS) of extracts from testicular vein blood and media of incubations with Leydig cells. Blood was collected from veins on the surface of the testes of anaesthetized boars. Collagenase-dispersed Percoll-purified cells (> 90% pure) were incubated (20 x 10(6) cells/flask) with androstenedione (8.75 mumol/l) or [3H]androstenedione (5 x 10(6) c.p.m.) for < 60 min. Steroids were recovered from plasma or media by solid-phase extraction and the unconjugated fractions chromatographed isocratically in two solvent systems (acetonitrile:water, 37:63 (v/v) and methanol:water, 70:30 (v/v)) before CGC-MS analysis. 19-Hydroxytestosterone was present in greater quantities than 19-hydroxyandrostenedione in testicular vein blood; it was also seen as a quantitatively significant metabolite of unlabelled and radioactive androstenedione in the incubation studies. The demonstration of the secretion of 19-hydroxyandrogens from porcine testes thus raises questions concerning the physiological significance of a testicular, rather than an adrenal, secretion of these compounds.

Relaxin is not associated with poor milk yield in the postpartum sow

Porcine relaxin (pRXN) titers were measured in 109 plasma samples drawn between 24 and 120 h post-partum from good (n = 34), and poor (n = 25) milking sows and from sows (n = 12) exhibiting overt signs of hypogalactia located on six swine farms in Ontario. Mean plasma pRXN titers among the three groups at 24 h post-partum were not significantly different although there was considerable variation. By 48 h however, the pRXN titers had declined markedly in all groups and between 72 and 120 h, pRXN was cleared from the plasma of all sows examined except one hypogalactic animal that had a titer of 1.13 ng/mL at 96 h. These results suggest that, although pRXN may be identifiable in the corpora lutea during the puerperium, it does not contribute to either hypogalactia or poor lactational performance in sows. The data also encourage the view that pRXN could be used at farrowing without deleterious effects on suckling.

A Delphi exercise used to identify potential causes of variation in litter size of Ontario swine

Forty-eight people, considered to the swine experts, were asked to collaborate in a Delphi exercise to identify the factors which they believed affect litter size in Ontario swine. The panel included 16 animal scientists, 16 pork producers, and 16 veterinarians in swine practice. The ten factors with the highest ratings were parity of the sow, mycotoxins in the feed, infections with porcine parvovirus or Leptospira spp., breeding gilts on their second versus first observed estrus, the timing of breeding with respect to the onset of estrus, purebred versus crossbred sows, boar overuse (bred by a boar that was mated more than six times per week), pen versus hand mating, age of gilt when first bred, and body condition of the sow at the time of conception. The experts did not agree about the effect on litter size of the sow's previous lactation, factors ensuring adequate nutrient intake during lactation, health of the sow and the boar, breed of a purebred sow, or the ease of mating the sow.Key items in the use of the Delphi technique to arrive at a consensus are discussed.

Cesarean section in the sow: A retrospective analysis of litter size and stillbirth rate

The purpose of this study was to examine the litter size and stillbirth rate associated with cesarean-derived litters and to examine the relationship between the number of previous cesarean sections a sow had experienced and litter size. The records of 856 cesarean sections during a ten-year period from 1978 to 1988 were examined. The mean litter size was 10.6 +/- 3.2 and the mean number of stillborn pigs per litter was 0.2 +/- 0.8. The low level of stillbirth observed in this study provides supportive evidence to many earlier publications suggesting that the majority of stillborn pigs die during the birth process itself.A negative correlation between the number of previous cesarean sections a sow had experienced and litter size (r(2) = 0.015, p < 0.001) was observed. The slope of the regression line was -0.55, suggesting that litter size is reduced by approximately one-half a piglet for each cesarean section the sow has previously experienced. There are many factors which influence the variation in litter size. The small correlation coefficient (r(2) = 0.015) observed in this study indicates that only 1.5% of the variation in litter size can be explained by the number of previous cesarean sections that the sow has experienced.

An evaluation of vulvomucosal injections of prostaglandins for induction of parturition in swine

Two trials were performed to evaluate the efficacy of prostaglandins administered via the vulvomucosal route at one-half the recommended dosage in comparison to prostaglandins injected intramuscularly (IM) at the standard dosage. In trial 1, sows on three commercial swine farms were given prostaglandin F2alpha at a dosage of 10 mg IM (n = 110) or 5 mg prostaglandin F2alpha using a vulvomucosal injection (n = 94). The numbers of sows farrowing within 36 h postinjection were 92 (84%) and 83 (88%), respectively. In trial 2, sows on four commercial swine operations were induced to farrow by means of one of three treatments: cloprostenol 175 mug IM (n = 71); cloprostenol 87.5 mug vulvomucosally (n = 57); or prostaglandin F2alpha 5 mg vulvomucosally (n = 96). The numbers of sows farrowing within 36 h postinduction were 69 (97%), 53 (93%), and 91 (94%), respectively.Vulvomucosal injections of prostaglandin F2alpha and cloprostenol at one-half the dosage appeared to be as effective as intramuscular injections of prostaglandin F2alpha and cloprostenol at the recommended level. There were fewer sows demonstrating restless behavior following the injection of lower dosages of prostaglandin F2alpha vulvomucosally, compared to sows given the recommended dosage of prostaglandin F2alpha IM.

Isolation of 11 beta-hydroxylated androgens from testicular vein blood of the mature boar

The isolation of 11 beta-hydroxyandrostenedione and 11 beta-hydroxytestosterone from testicular vein blood of the mature male domestic pig is described. Blood was collected from veins and arteries on the surface of the testes of mature boars. Steroids were extracted from plasma with SEP-PAK C18 cartridges and recovered with acetonitrile. A separation of steroids was made by high performance liquid chromatography (HPLC) using acetonitrile/water (37/63; v/v), and fractions were collected manually with detection at 254 nm. Preliminary identification was based on comparison with the HPLC retention time of an authentic steroid standard. Final characterization was achieved by means of capillary gas chromatography-mass spectrometry (GC-MS). The findings record the first evidence for the secretion of C19-11-hydroxylated steroids by normal testes in a mammalian species.

Aromatization of 19-norandrogens by porcine Leydig cells

The aromatization of norandrogens was investigated with highly purified preparations of Leydig cells from mature male pigs. Cell incubations with norandrostenedione and nortestosterone gave rise to large amounts of estrone sulfate in the medium as determined directly by a specific radioimmunoassay (RIA). Estrogen production was at least equal to that seen with androstenedione and testosterone as substrates. Similar findings were made with cells in culture for 5 days before addition of the androgen substrates in a 4h-test of aromatase activity. Stimulation of estrogen formation was noted when cells were exposed for 48 h to either hCG (0.5 i.u.) or FGF-beta (10 ng) daily, as a pretreatment, before adding androstenedione for the test of aromatase activity. Little or no increase was seen with norandrostenedione or nortestosterone as substrate. Further evidence for estrogen production was obtained from HPLC separations of metabolites of cell incubations with norandrostenedione and [14C]nortestosterone monitored by RIA and radioactivity, respectively. It is suggested that norandrogens could serve as important substrates for aromatization in the boar testes.