University of Novi Sad, Faculty of Agriculture, 21000 Novi Sad, Trg D, Obradovića 8, 21000 Novi Sad, Serbia.
Reprod Biol Endocrinol. 2012 Aug 22;10:61. doi: 10.1186/1477-7827-10-61.
Prolonged 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.
Two 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.
Ovulations 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).
In 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.
在伏伊伏丁那的大型养殖场中，多达 30%的后备母猪因发情前期（即青春期延迟）而被淘汰。确定这些母猪是无周期（青春期前）还是有周期但未能表现出发情行为至关重要。最近的研究表明，用马绒毛膜促性腺激素（eCG）处理可以增加性成熟母猪的发情周期持续时间。基于这些发现，本研究的目的是确定注射 eCG 后青春期延迟母猪的繁殖状况。
在伏伊伏丁那的一个养猪场进行了两项实验。在实验 1 中，20 头青春期前（无周期）和 120 头性成熟（有周期）的母猪，在自发发情检测后第 5、11 或 17 天，分别注射 400 IU eCG+200 IU 人绒毛膜促性腺激素（hCG）或 1000 IU eCG（性成熟母猪），以确定它们的卵巢反应和诱导发情表现。在实验 2 中，从繁殖群中淘汰 60 头青春期延迟的母猪（直到 8 月龄才发情，平均 258 天），并进行屠宰以根据卵巢解剖学特征确定其繁殖状态。第二组母猪（n=60）接受单次 1000 IU eCG 注射，根据 eCG 注射到发情检测的间隔时间和持续时间来确定其繁殖状态。数据采用描述性统计、t 检验、方差分析和 Duncan 检验进行分析。
在注射 eCG 后，90%的无周期（青春期前）和平均 93.3%的有周期（性成熟）母猪诱导排卵。在注射 eCG 后平均 4 天，85%的处理无周期（青春期前）母猪和 95%（19/20）的处理有周期（性成熟）母猪发情。在注射 eCG 后第 5 天和第 11 天，分别有 95%（19/20）和 90%（18/20）的性成熟母猪发情，发情检测间隔时间延长（平均 25 天）。在注射 eCG 后第 5 天和第 11 天，40 头无发情的母猪达到了周期性的青春期卵巢活动。在接受单次 1000 IU eCG 注射后，56 头母猪（总处理母猪的 93.3%，平均 259 天龄）表现出发情。在 60 头接受延长 eCG 至发情间隔时间（平均 24.7 天）的母猪中，有 34 头（总发情母猪的 60.7%）被认为是自发的性成熟（有周期），但在治疗前表现为行为性无发情。其余 22 头（发情母猪的 39.3%）在治疗前被认为是真正的青春期前（无周期），或在自发发情周期的黄体期或发情前期接受了 eCG 注射（实验 2）。
在 66.7%的青春期延迟母猪中，在死后检查卵巢时发现了排卵前卵泡（PoF）、 corpora hemorrhagica（CH）、corpora lutea（CL）或 corpora albicantia（CA）。这些母猪在屠宰前被认为是性成熟的。在 60.7%的青春期延迟母猪中，在注射 eCG 后平均 24.7 天检测到行为发情。这些母猪被认为是在自发发情周期的黄体期（发情后期）接受了 eCG 处理。这两个发现都表明，在从繁殖群中淘汰之前，青春期延迟的母猪实际上已经达到了周期性的青春期卵巢活动（性成熟）。
