Sows exposed to octylphenol in early gestation: no estrogenic effects in male piglets, but increased rate of stillbirth.

Octylphenol is an industrial chemical with estrogenic effects both in vitro and in vivo. In this study the effects of short-term intramuscular exposure to 0.1 mg/kg of body weight and 1.0 mg/kg of body weight in early gestation were evaluated in pregnant sows with respect to reproductive parameters in the newborn male piglets, as compared with male piglets from unexposed control sows. The male piglets were examined immediately after birth with respect to the macroscopic appearance of the reproductive organs and testosterone concentration in serum. It was not possible to identify any estrogenic effects in the newborn male piglets. However, in the sows exposed at the highest level of octylphenol, there was an increased number of stillborn piglets and an increased proportion of sows with stillborn piglets in the litter (P < 0.05). This was an unexpected finding which has not been reported previously.

The development of a model for artificial insemination by backyard pig farmers in Thailand.

The aim of this study was to develop and evaluate a model of artificial insemination (AI) technology transferable to backyard pig farmers for strengthening pig productivity in rural areas in Thailand. An AI center, criteria and process for farmer selection, an AI training program, AI practice in pigs, and a backyard farmer network were created as a model. Five hundred and thirty-one farrowing records from 307 sows were analyzed. Farrowing rates (FR), total number of piglets born (TB), and number of piglets born alive (BA) were studied. AI has led to better results in FR, TB, and BA than natural mating (P < 0.05). Demographic factors such as sex and age of farmers only had significant effects on FR (P < 0.05), while educational levels and farmers' AI experience had significant effects on TB and BA (P < 0.05). Model factors such as type of training, semen delivery systems, and semen storage time did not have significant effects on FR, TB, and BA. In conclusion, using this model, we found that backyard farmers could be trained in AI techniques in order to achieve equally good results as experienced technicians. Male farmers within working age or older, with a high school education or higher are the recommended target groups for implementing this model. Strong cooperation with clear responsibilities of all stakeholders could create a good network of backyard pig farmers. Therefore, the implementation of AI techniques in pig production can be applied to the target group with an aim towards a sustainable, self-sufficient community.

Influence of repeat-service and weaning-to-first-service interval on farrowing proportion of gilts and sows.

The present study was performed to evaluate different components of reproductive failure after service under a tropical climate and to investigate the influence of repeat-service and delayed wean-to-service interval (WSI) on subsequent fertility in gilts and sows. The study was conducted in four commercial swine breeding herds in the northeastern part of Thailand. Data were collected during a 3-year period from July 2005 to June 2008. A total of 30,058 insemination records from 9037 gilts and sows was included. On average, the farrowing proportion (FP) was 81.9% and adjusted FP (excluding gilts/sows culled after service) was 85.3%. The reasons for the failure to farrow included return-to-oestrus 9.4%, abortion 1.7%, not being pregnant 1.0% and not-in-pig 2.0%. Non-repeat-service females had 83.7% FP, while those that experienced repeat-serviced for 1, 2 and > or = 3 times had 71.2%, 57.7% and 43.4% FP, respectively (P<0.001). The seasonal influence on FP was observed in non-repeat-serviced females, but not in those that experienced repeat-service. Sows mated during 0-6 days after weaning had 86.8% FP, while those mated 7-10, 11-20 and 21-60 days after weaning had 78.9%, 78.9% and 78.4% FP, respectively (P<0.001). It is concluded that repeat-service in gilts/sows resulted in a 12.5% decrease in FP. Sows returning to oestrus later than 6 days after weaning had 7% lower FP than sows mated within 6 days after weaning.

Comparison of artificial insemination with natural mating on smallholder farms in Thailand, and the effects of boar stimulation and distance of semen delivery on sow reproductive performance.

Following the implementation of artificial insemination (AI) services for smallholder pig farms, we investigated the reproductive performance after AI and its influencing factors. A small-scale boar station with an AI lab was established with two active boars having good genetics and free from reproductive diseases. Individual sow cards were used for reproductive data recording. A total of 171 sows on 92 farms situated within a radius of 50 km from the AI center were included in this study. Sows bred by AI (n = 121) were inseminated twice per estrus by two trained inseminators. A further 50 sows were mated by natural services using local rental boars. The impact of boar stimulation and distance from the AI center to the farm were also determined. Non-return (P = 0.02) and farrowing rates (P = 0.03) were higher for AI than for naturally bred sows (84.0% and 76.0% vs. 74.0% and 70.0% for AI and naturally bred, respectively). For sows bred by AI, boar stimulation increased non-return rate (84.1% vs. 70.0%; P = 0.09), farrowing rate (83.7% vs. 69.2%; P = 0.01) and litter size (11.2 +/- 2.3 vs. 9.7 +/- 1.7; P < 0.01). There was no effect on performance due to distance of semen transport. These results clearly indicate that sow performance on smallholder farms will improve if AI is utilized and boar stimulation is employed.

The association between growth rate, body weight, backfat thickness and age at first observed oestrus in crossbred Landrace x Yorkshire gilts.

The present study aims to investigate the association between growth rate (GR), body weight (BW), backfat thickness (BF) and age at first observed oestrus in crossbred Landrace x Yorkshire (LY) replacement gilts in the tropics. The study was carried out on five commercial swine herds in Thailand between 2004 and 2006. A total of 6946 LY gilts were included. The gilts entered the herd at about 163 days of age. The BW (kg) and BF (mm) of the gilts were measured when the gilts entered the gilt pools and again when the gilts were sent to the breeding house. The GR from birth to entry into the gilt pools (birth to 90 kg BW) (GRe), the GR from entry into to exit from the gilt pools (91-134 kg BW) (GRi) and the GR from birth until the gilts were sent to the breeding house (birth to 134 kg BW) (GRs) were calculated. The relationship between age at first observed oestrus and GRe, GRs, GRi, BW and BF were analyzed. Pearson's correlation and four general linear models (GLMs) were conducted. On average, the gilts showed first observed oestrus at 200+/-28 days of age. The means of age at first observed oestrus varied from 188 to 251 days (P<0.001) among the herds. The GRs of the gilts significantly correlated with the BW (r=0.55, P<0.001) of the gilts when they were sent to the breeding house and the age at first observed oestrus (r=-0.40, P<0.001). Gilts with a high GRe and GRs were younger at first observed oestrus compared to gilts with a low GRe and GRs. On average, the gilts with GRs of over 604 g/day showed first observed oestrus before 5 months of age. GRi was not correlated with the age at first observed oestrus (P>0.05). Neither the BF of the gilts at entry nor the BF that the gilts gained within the gilt pools significantly correlated with age at first observed oestrus (P=0.29 and P=0.69, respectively). But the gilts with a higher BF at entry tended to have a higher BW when they were sent to the breeding house (r=0.44, P<0.001). The present study indicates that replacement gilts with a high GR (both GRe and GRs) tend to show sign of oestrus earlier than gilts with a low GR (both GRe and GRs).

Effect of season and outdoor climate on litter size at birth in purebred landrace and yorkshire sows in Thailand.

The objective of the present study was to retrospectively investigate causes of variation on litter size at birth (total number of piglets born per litter (TB) and number of piglets born alive per litter (BA)) of Landrace (L) and Yorkshire (Y) sows in swine nucleus herds in Thailand. The data included sows farrowed during a four-year period from January 1998 to December 2001. The analyzed data set included observations on 8020 litters from 2199 L sows and 6919 litters from 1680 Y sows. Analysis of variance (ANOVA) was applied for statistical analyses using General Linear Mixed Model (MIXED) procedure of SAS. No breed difference was found for both TB and BA. Farrowing months significantly influenced TB and BA (P<0.001). Sows farrowed in August and September had a lower BA than sows farrowed from November to June (P<0.05). Effect of farrowing months on both TB and BA was more pronounced in primiparous compared with multiparous sows. Average minimum daily temperature during gestation negatively correlated with both TB and BA, average maximum daily temperature during gestation negatively correlated with BA and average daily humidity during gestation negatively correlated with both TB and BA. The correlations were stronger in L than in Y sows.

A study on the number of recovered spermatozoa in the uterine horns and oviducts of gilts, after fractionated or non-fractionated insemination.

The objective of this study was to compare the number of recovered spermatozoa, in different parts of the uterine horn and oviduct in gilts, after insemination with fractionated (experiment) and non-fractionated (control) liquid stored semen. The number of spermatozoa and volume of backflow was also investigated. Twenty three cross-bred gilts were used in the study. They were divided into 2 groups, a control group (non-fractionated liquid stored semen, n=10) which were inseminated with 100 ml of liquid stored semen containing 3,000 million spermatozoa per dose and an experimental group (fractionated liquid stored semen, n=10) which were inseminated with 50 ml of liquid stored semen, with 3,000 million spermatozoa per dose and followed by another 50 ml of semen dilutor (Beltsville Thawing Solution, BTS). Thereafter, backflow semen was collected and measured every 15 min for a period of 1 hr. Three or 12 hr after insemination, 5 gilts from each group had the uterus, the horn of the uterus, the oviducts and the ovaries removed under general anaesthesia. The horn of uterus and the oviducts were seperated by ligation into 6 segments. All 6 segments were flushed with BTS to collect all spermatozoa within the segment. Recovered spermatozoa were counted, using a haemocytometer and the volume recorded. It was seen that the percentage of spermatozoa in the backflow semen in the experimental group was less than in the control group. The difference was not significant in the gilts that were operated on 3 hr after insemination, the mean number of spermatozoa in the uterine horn and the utero-tubular junction (UTJ) was more in the experimental than in the control group, but less in the isthmus and the ampulla of the oviduct. The gilts which were operated on 12 hr after insemination, had relativity more ovulating gilts in the control group than in the experimental group (3 of 4 gilts compare to 3 of 5 gilts). The control group had more spermatozoa in the oviduct than the experimental group, but less in UTJ and in the horn of the uterus. Again the difference was not significant. It can be concluded that fractionated (experimental) or non-fractionated (control) insemination of semen with the same number of spermatozoa provides no significant difference in the number of spermatozoa either in the horn of the uterus, the UTJ or the oviduct of gilts.