Blagoje Stančić

Ovarian activity and uterus organometry in delayed puberty gilts

About 30% of the total number of gilts selected for reproduction at the large breeding farm units in Vojvodina (Republic of Serbia) are culled due to prolonged pre-insemination anoestrus (estrus not detected until 8 mo of age). The aim of this study was to provide the answer to the following question: do the culling gilts reach cyclic ovarian activity at all? One hundred seventy five culled gilts in which external estrus manifestations were not detected by 8 mo of age were sacrificed and their reproductive organs were examined for determination of sexual maturity (ovaries exhibiting pre-ovulatory follicles 8 to 11 mm in diameter, corpora hemorrhagica, corpora lutea and corpora albicantia). Uterine weights and horn length were also determined. Functional ovaries were observed in 107 (61.1%) examined gilts, with 62 animals having one and 45 having two puberty ovarian cycles (57.9% and 42.1%, respectively). Pathomorphological changes which could result in prolonged pre-insemination anoestrus were not observed on the reproductive organs of sexually mature gilts. Our results indicate that most of the culling gilts have reached cyclic ovarian activity. The main reason for culling due to the absence of external estrus manifestations in sexually mature gilts could be inadequate estrus detection technology.

Fertility of sows after intracervical or intrauterine insemination with different spermatozoa number in reduced volume doses.

Modern intensive pig production demands an increasing number of insemination doses per ejaculate of genetically superior boars. In order to achieve such a result the possibility of producing insemination doses in both reduced volume and spermatozoa count without decreasing the fertility of sows is studied. In this trial we studied the effect of insemination with reduced volumes of semen (50 mL) and varied spermatozoa count (4, 2 or 1x109). Insemination was performed by the classical (intracervical) or by the new (intrauterine) techniques and the basic fertility parameters (farrowing % and litter size) were measured. The farrowing value decreased with decreasing spermatozoa numbers after intracervical and intrauterine insemination. However, the farrowing value, regardless of spermatozoa numbers, was significantly higher after intrauterine insemination (83.3%, 76.7%, 66.7%) compared to the classical intracervical insemination (73.3%, 66.7% and 50%). Litters size did not vary significantly depending on the applied insemination procedure or spermatozoa number. These results indicate that application of the new intrauterine insemination procedure enables the use of doses with a smaller volume and spermatozoa number, at the same time obtaining a satisfactory farrowing and litter size. This opens the possibility of obtaining a significantly higher number of doses per ejaculate when compared to the classical intracervical insemination procedure. In such a way can be increased significantly the degree of reproductive exploitation of genetically superior boars.

Ovarian reaction and estrus manifestation in delayed puberty gilts after treatment with equine chorionic gonadotropin

BackgroundProlonged pre-insemination anestrus (i.e. delayed puberty) is a major contributing factor for culling up to 30% of the replacement gilts at large breeding farm units in Vojvodina. It is imperative to determine if these gilts are acyclic (prepubertal) or cyclic, but just fail to exhibit behavioural estrus. Recent investigations demonstrate that treatment with equine chorionic gonadotropin (eCG) can increase the diestrous phase duration in sexually mature gilts. Based on these finding, the aim of the present studies was to determine the reproductive status of delayed puberty gilts following injection with eCG.MethodsTwo experiments were conducted on a swine breeding farm in Vojvodina. In Exp. 1, 20 prepubertal (acyclic) gilts, and 120 sexually mature (cyclic) gilts were injected with a single injection of 400 IU eCG + 200 IU human chorionic gonadotropin (hCG) or with 1000 IU eCG (cyclic gilts), at d5, d11 or d17 after spontaneous estrus detection, to determine their ovarian reaction and induced estrus manifestation. In Exp. 2, sixty delayed puberty gilts (estrus not detected until 8 month of age, av. 258 days) were culled from breeding herd and slaughtered to determine their reproductive status based on ovarian anatomical features. The second group of gilts (n = 60) was treated with a single 1000 IU eCG injection to determine their reproductive status, based on the interval between eCG injection to estrus detection and duration. The data were analyzed by descriptive statistics, t-test, analysis of variance and Duncan’s test in the software package Statistics 10th.ResultsOvulations were induced in 90% of acyclic (sexually immature) and, on average, 93.3% of cyclic (sexually mature) gilts after the eCG injection. On average, 4 days after the eCG injection, estrus was detected in 85% of the treated acyclic (sexually immature) gilts and in 95% (19/20) of the cyclic (sexually mature) gilts, treated with eCG on day 17 after spontaneous estrus detection. The interval from eCG to induced estrus detection was prolonged (av. 25 days) in 95% (19/20) of the sexually mature gilts treated with eCG on day 5 and in 90% (18/20) of gilts treated on day 11 after spontaneous estrus detection (Exp. 1). Forty anestrous gilts reached cyclic pubertal ovarian activity. Estrus manifestation was detected in 56 gilts (93.3% of the total 60 treated prolonged anestrous gilts, av. 259 days of age), after a single 1000 IU eCG injection. Thirty-four gilts (60.7% of the total gilts in estrus) with prolonged eCG to estrus interval (av. 24.7 days) were considered spontaneously cyclic (sexually mature), but behaviourally anestrous before treatment. The remaining 22 (39.3% of the total gilts in estrus) were considered truly sexually immature (acyclic) before the treatment or were eCG injected in the late luteal or proestrous phase of spontaneous estrous cycle (Exp. 2).ConclusionsIn 66.7% of the delayed puberty gilts, pre-ovulatory follicles (PoF), corpora hemorrhagica (CH), corpora lutea (CL), or corpora albicantia (CA) were found on the ovaries upon post mortem examination. These gilts were considered as sexually mature before slaughtering. In 60.7% of the delayed puberty gilts, behavioural estrus was detected an average of 24.7 days following eCG injections. These gilts were considered as eCG treated during the luteal phase (diestrus) of the spontaneous estrus cycle. Both findings suggest that delayed puberty gilts actually reached cyclic pubertal ovarian activity (sexual maturity) before culling from the breeding herd.

Effect of season, breed and age on the quality of boar sperm 1: The native sperm

Total of 182 ejaculates were investigated in regard to the effect of season breed and age on the quality of boar sperm. The boars of Yorkshire Landrace, Duroc, Hempshire and Pietrain pure breeds and Fr crossbred pigs were divided according to age in four groups: 12, 13-18, 19-24 and 25 months. Ejaculates were examined in the following seasons: January-March April-June, July-September and October-December. Differences in ejaculate volume, total number, concentration and progressive motility (PM), as well as number of ejaculates with less then 65% PM, were estimated within seasons, breeds and age of boars. These results suggest that quality of every single ejaculate must be evaluated before using for AI.

Effect of season on fertility of sows

Reduced fertility of sows during the warmer period of the year is a well-known occurrence in practical production. Namely, during summer months gilts become sexually mature later, the interval from weaning to estrus is prolonged, there is a greater number of postlactation silent estruses anestrias and ovarian cysts, the value of conception is lower, there are more irregular failed fertilizations, there is a higher degree of embryo mortality, and the litter size is smaller. This is why this occurrence presents an important zootechnological, veterinary-medical and economic problem. Most scientific research shows that this phenomenon is a consequence of the effects of an extended daily photoperiod and a higher ambient temperature. However, the degree of the individual effect of these factors has not been determined clearly, or the physiological and endocrinological mechanisms of their action. It is probably not possible completely to avoid the negative influence of seasonal factors on reduced fertility in sows during the summer period. However, it can be significantly alleviated with a regular maintenance technology, diet, hygiene and medical protection of sows. This paper presents knowledge acquired so far on the manifestation of this phenomenon, its physiological and endocrine bases, as well as possibilities for its practical resolving.