Luteinizing hormone (LH) response to different doses of synthetic gonadotropin releasing hormone (GnRH) in prepubertal gilts

The object of this investigation was to study luteinizing hormone (LH) response to different doses of synthetic gonadotropin-releasing hormone (GnRH) in prepubertal gilts. Four crossbred prepubertal gilts, 128–134 days old and body weight 57–63 kg, were used in this study. Four doses, 0. 5, 25 and 125 μg, of GnRH were administered via a jugular vein catheter in a latin square design. Each treatment consisted of 3 injections at 90 min intervals. Frequent blood samples were taken during a period of 90 min before up to 90 min after treatment. Total LH responses were measured from post-treatment samples as the area under the curve above base level obtained from pre-treatment samples. A positive relationship between GnRH dose and LH release was obtained in all gilts, except for 1 treatment given to a gilt with high plasma level of oestradiol-17β on the day of treatment. This study has demonstrated the responsiveness of the pituitary gland by LH release to different doses of GnRH in 4.5-month-old prepubertal gilts.     

Sperm distribution in the reproductive tract of sows after intrauterine insemination

The purpose of the present study was to compare the number of spermatozoa obtained from different parts of the oviducts and the uterine horns of sows after intrauterine insemination (IUI) and conventional artificial insemination (AI), 24 h after insemination. Twelve crossbred (Landrace x Yorkshire) multiparous sows were used in the experiment. The sows were examined for standing oestrus using a back pressure test and were examined every 4 h after standing oestrus by real-time B-mode ultrasonography to estimate the time of ovulation. The sows were allocated to two groups, group I sows (n = 6) were inseminated by a conventional AI technique with 3 x 10(9) motile spermatozoa in 100 ml of extended semen, and group II sows (n = 6) were inseminated by an IUI technique using 1 x 10(9) motile spermatozoa in 50 ml of extended semen. A single dose of AI or IUI was given using the same boar, 8-10 h before the expected time of ovulation during the second oestrus after weaning. Twenty four hours after insemination, the sows were ovario-hysterectomized. The oviducts and the uterine horns were removed and divided into seven parts, the cranial, middle and caudal uterine horns, the utero-tubal junction (UTJ), the cranial and caudal isthmus, and the ampulla. All parts of the reproductive tract were flushed and the spermatozoa were counted using a haemocytometer. The results revealed that the spermatozoa were found in both the oviducts and the uterine horns in all animals. The number of flushed spermatozoa in the UTJ of groups I and II, was 142,500 and 131,167 (p > 0.05), and in the caudal isthmus was 1411 and 1280 (p > 0.05), respectively. The proportion of spermatozoa in different parts of the reproductive tract in relation to the total number of spermatozoa within the tract was not significantly different between groups I and II (p > 0.05). It could be concluded that IUI, with a three-time reduction in the number of spermatozoa used resulted in the same number of spermatozoa to be deposited in the sperm reservoir around ovulation time.     

Clinical and endocrinological studies in primiparous post partum sows. Effects of lactation length and litter size

The object of this investigation was to determine the relationships between clinical findings and hormonal patterns in primiparous sows with different lactation length and litter size during lactation, weaning and to the first oestrus. Seven pairs of primiparous full sib sows were used to determine the effect of lactation length with normal litter size. One sow of each pair was assigned to nurse the piglets for 3 weeks (group A) while the other nusred for 5 weeks (group B). Another 8 primiparous sows (group C) were assigned to nurse 2–4 piglets during a 5-week lactation period. Oestrus detection was performed twice daily and laparoscopic examination every 2 weeks. If the sows did not come in oestrus within 3 weeks after weaning they were slaughtered. Peripheral plasma levels of progesterone, oestradiol-17β and LH were estimated by radioimmunoassays throughout the experimental period.     

Investigation into the use of prostaglandin F2 alpha (PGF2 alpha) and oxytocin for the induction of farrowing

This experiment was conducted in order to compare the effects of injecting PGF2 alpha alone, PGF2 alpha with oxytocin and placebo on the induction of farrowing in swine and to compare the relative effects of 3 different dosages of oxytocin (10, 20 and 30 iu per animal) when combined with PGF2 alpha (10 mg). The findings revealed that animals treated with 30 iu oxytocin farrowed within 10.6 h which was similar to those receiving PGF2 alpha only (9.4 h), but shorter than control animals (53.6 h). Animals receiving 20 and 10 iu of oxytocin farrowed within 1.4 and 1.7 h, respectively. Difficult farrowings requiring manual assistance occurred in 30%, 30%, 50% and 10% of sows given 30 iu, 20 iu and 10 iu of oxytocin and in the control group, respectively. Thirteen of 73 sows treated with PGF2 alpha farrowed within 12.6 +/- 5.3 h. Stillbirths were highest (10.2%) in the control animals whilst in the others it was under 7%. Oxytocin at dosages of 20 and 10 iu, seemed most promising in terms of synchronising farrowing following PGF2 alpha treatment in swine. However, farrowing complications were more common in these groups.     

Plasma levels of cortisol in zero-weaned and lactating sows during the first two weeks post partum

The object of this investigation was to study the plasma levels of cortisol during the day of parturition and the first two weeks post partum in primiparous zero-weaned (weaned within 12 hr after birth) and lactating sows. Fourteen primiparous sows were used. They were grouped as follows: group A, (3 sows) zero-weaned, ovulating; group B, (4 sows) zero-weaned, anovulatory; group C, (4 sows) lactating with normal litter size; group D, (3 sows) lactating with small litter size. The peripheral plasma levels of cortisol were determined by radioimmunoassay throughout the experimental period,The peripheral plasma levels of cortisol were significantly higher in the anovulatory than in the normally ovulating sows. The lactating sows had almost the same levels of cortisol as the zero-weaned sows with anovulatory estrus. There was no difference in cortisol levels between sows nursing small or normal litters.It may be concluded that elevated plasma levels of cortisol might be one of several factors inhibiting the LH surge during the first estrus after zero-weaning. No relationship was found between cortisol levels and number of suckling piglets.     

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.     

The effect of activation protocols on the development of cloned goat embryos

This study was conducted to compare the developmental competence of somatic nuclear transfer (NT) embryos, after either ionomycin or ethanol activation, in locally bred goats. Donor cells were prepared from the ear skin fibroblasts of a female goat. Cells, at passage 3-8, starved by culturing in 0.5% FCS for 4-8 d, were used for NT. Immature oocytes were obtained from FSH-stimulated goats and matured for 22 hr before enucleation and NT. After fusion, the reconstructed embryos were activated with either ionomycin or ethanol followed by culturing in 6-dimethylaminopurine (6-DMAP) and cytochalasin B (CB), for 3 hr. In experiment I, the fused NT embryos (n=63, ionomycin and n=68, ethanol treatments, respectively) were cultured in B2 with a Vero co-culture system and their developmental competence was evaluated through to Day 9. In experiment II, the NT embryos at the 2-4 cell stage on Day 2 derived from each treatment (ionomycin n=46, and ethanol n=37), were transferred into 10 synchronous recipients. There were no significant differences between the NT embryos derived from the ionomycin and ethanol groups, in fusion (86.3% versus 82.9%), cleavage (90.5% versus 82.4%) and for morula/blastocyst development rates (9.5% versus 5.9%). Sixty percent (3/5) of the recipients from ionomycin became pregnant by midterm (2.5 mts) while only 20% (1/5) from ethanol treatment was pregnant by Day 45. The results demonstrate that activation with either ionomycin or ethanol in combination with 6-DMAP-CB treatment does not affect the development of cloned goat embryos.