公猪诱情对后备母猪初情期的影响

<正>后备母猪发情可通过许多日常管理来实现,与成熟公猪的接触来刺激,可使发情日龄提前。在诱情过程中,公猪要经常替换,避免习惯性,以保持兴趣。公猪单独饲喂,每天将公猪赶到母猪栏内诱情,进行可靠的刺激,促使小母猪早些达到初情期。笔者从2012年9月至2013年4月对黄陵基础母猪存栏数800头的某猪场进行追踪,对新引进后备母猪160日龄时与公猪接触后对发情影响的统计,总结了后备母猪与公猪接触对发情的影响。     

荣昌猪后备母猪发情规律的研究

观察31头荣昌后备母猪第1~4个情期的采食量变化情况、情期阴户变化并测量记录每个猪发情盛期时的体重和日龄。研究结果与前人的结论有一定差异,研究认为,对荣昌后备母猪的测定宜在初情期前开始,即3月龄开始,荣昌后备母猪培育的最佳结束月龄宜5月龄,即第三情期结束(150 d即体重45 kg左右较为合适),最佳配种月龄为6月龄(即三次情期后再发情配种效果好)。     

3种非传染性因素引起的母猪繁殖障碍

非传染性因素引起的母猪繁殖障碍主要有:青年母猪初情期延迟,经产母猪断奶后不发情或发情延迟,多次配种不孕,隐性发情,卵巢及子宫疾病等等。1初情期迟缓发育正常的外来品种后备母猪,若达7月龄后仍未见发情的,即可视为初情期迟缓。1.1原因1.1.1饲养管理不当。后备母猪在培育期间     

公猪诱情对后备母猪初情期和经产母猪断奶后发情配种的影响试验

就现在普遍存在的青年母猪性成熟及经产母猪断奶后发情延迟现象,我们于2002年在本场,进行了公猪诱情对后备母猪初情期和经产母猪断奶后发情配种的影响试验。选择本场4月龄大约克后备母猪48头,随机分成试验组和对照组,每组24头,每组6个重复(栏),每个重复4头。两组后备母猪饲养于环境条件完全相同的不同后备猪舍中,试验组后备母猪达160日龄起每天以栏为单位与成年公猪同栏接触2次,每次15～20分钟,直至初情期到来。对照组后备母猪不接触公猪。选择本场体况、胎次相近大约克经产断奶母猪32头,随机分为试验组和对照组,每组16头,每组4个重复(栏),…     

后备母猪不发情的预防与处理

1预防应在160日龄时让公猪跟母猪每天接触1~2小时,诱导其发情,用不同公猪多次刺激比同1头公猪效果更好。后备母猪在160日龄以后,需要每天到栏内用压背结合外阴检查法来检查其发情情况。对发情母猪要建立发情记录,为将来的配种做准备,还可     

高原母猪配种间隔的调查研究

通过对青海省互助猪保种场2000-2008年的配种产仔记录统计分析表明,该场不同品种的配种间隔介于21.80～27.60d,平均配种间隔为25.02d;配种间隔随胎次增加而缩短;不同品种猪在同一胎次的配种间隔无显著差异(P＞0.05).通过对2008年128头次母猪在一个情期内的发情配种记录分析得出,该场母猪在一个情期内主要集中在断奶后6～8d内发情配种,并且该期间的情期受胎率也较高;同时母猪的配种间隔与季节有一定的关系,在春、夏、秋季较短,冬季较长.     

不同输精时间间隔对异常发情母猪和后备母猪生产性能的影响

本实验旨在探究不同输精时间间隔对异常发情母猪与后备母猪生产性能的影响。实验1选取健康且体况相近的1～5胎长大二元异常发情母猪210头,根据输精次数和输精间隔分为12 h组（发情立即配种,平均每间隔12 h输精1次,连续输精3次）和24 h组（发情立即输精,间隔24 h再输精1次）,每个处理3个重复,每个重复35头猪。实验2选取长大二元后备母猪390头,分为12 h组与24 h组,每个处理3个重复,每个重复65头猪。结果表明：后备母猪12 h组与24 h组间配种受胎率、配种分娩率、窝均总产仔数、窝均健仔数以及繁殖力指数均无显著差异,异常发情母猪12 h组的配种受胎率、配种分娩率以及繁殖力指数均高于24 h组（P<0.05）。经济效益分析发现,生产中后备母猪采用间隔24 h复配1次的配种模式,异常发情母猪应采用每间隔12 h复配1次连续配种3次的配种模式,按照上述配种模式,生产批次内每配种10头异常发情母猪,可额外增加5 376.3元的盈利。由此可见,针对不同类型母猪采用不同配种方式可增加猪场盈利。     

利用发情经产母猪诱情对后备母猪初情期影响的试验研究

选择5月龄丹系长白后备母猪60头,随机分成试验组和对照组,每组30头,每组5个重复(栏),每个重复6头。试验组达161日龄起每天以栏为单位与发情经产母猪同栏接触2次,每次15~20 min,直至180日龄;对照组达161日龄起每天以栏为单位与成年公猪同栏接触2次,每次15~20 min,直至180日龄。结果:试验组和对照组后备母猪180日龄内的初次发情率和初情期分别为63.33%、179.82 d和70.00%、176.54 d。表明2种诱情法的效果基本相同,都能有效促进后备母猪初情期提前,故利用发情经产母猪诱情代替公猪诱情是可行的。     

互助猪配种间隔的调查研究

通过对互助八眉猪保种场2000 - 2008年的配种产仔记录统计分析表明,该场不同品种的配种间隔介于21.80～27.60d,平均配种间隔为25.02d;配种间隔随胎次增加而缩短;不同品种猪在同一胎次的配种间隔间无显著差异(P＞0.05).并对2008年128头次母猪在一个情期内的发情配种记录分析得出,该场母猪在一个情...     

运动及公猪刺激对后备母猪发情率的影响

为了研究运动及公猪刺激对后备母猪发情率的影响,试验以6月龄长白×大白二元后备母猪为研究对象,分别通过公猪刺激、运动加公猪刺激两种处理方式比较对后备母猪发情的影响。结果表明:公猪刺激组、运动加公猪刺激组后备母猪的发情头数和发情率均极显著地高于对照组(P0.01);运动加公猪刺激组后备母猪发情率达到72.6%,极显著地高于对照组和单纯公猪刺激组(P0.01),可以作为促进后备母猪正常发情的有效措施应用于生产实践。     

Effect of age and physical or fence-line boar exposure on estrus and ovulation response in prepubertal gilts administered PG600

Boar exposure has been used for estrus induction of prepubertal gilts, but has limited effect on estrus synchronization within 7 d of introduction. In contrast, PG600 (400 IU of PMSG and 200 IU of hCG; Intervet, Millsboro, DE) is effective for induction of synchronized estrus, but the response is often variable. It is unknown whether boar exposure before PG600 administration might improve the efficiency of estrus induction of prepubertal gilts. In Exp. 1, physical or fence-line boar contact for 19 d was evaluated for inducing puberty in gilts before administration of i.m. PG600. Exp. 2 investigated whether 4-d boar exposure and gilt age influenced response to PG600. In Exp. 1, 150-d-old prepubertal gilts were randomly allotted to receive fence-line (n = 27, FBE) or physical (n = 29, PBE) boar exposure. Gilts were provided exposure to a mature boar for 30 min daily. All gilts received PG600 at 169 d of age. Estrous detection continued for 20 d after injection. In Exp. 2, prepubertal gilts were allotted by age group (160 or 180 d) to receive no boar exposure (NBE) or 4 d of fence-line boar exposure (BE) for 30 min daily before receiving PG600 either i.m. or s.c. Following PG600 administration, detection for estrus occurred twice-daily using fence-line boar exposure for 7 d. Results of Exp. 1 indicated no differences between FBE and PBE on estrus (77%), age at puberty (170 d), interval from PG600 to estrus (4 d), gilts ovulating (67%), or ovulation rate (12 corpora lutea, CL). Results from Exp. 2 indicated no effect of age group on estrus (55%) and days from PG600 to estrus (4 d). A greater (P < 0.05) proportion of BE gilts expressed estrus (65 vs. 47%), had a shorter (P < 0.05) interval from PG600 to estrus (3.6 vs. 4.3 d), and had decreased (P < 0.05) age at estrus (174 vs. 189 d) compared with NBE. Ovulation rate was greater (P < 0.05) in the BE group for the 180-d-old gilts (12.7 vs. 11.9 CL) compared with the NBE group. However, age group had no effect on ovulation (77%) or ovulation rate (12 CL). Collectively, these results indicate that physical boar contact may not be necessary when used in conjunction with PG600 to induce early puberty. The administration of PG600 to 180-d-old gilts in conjunction with 4 d prior fence-line boar exposure may improve induction of estrus, ovulation, and decrease age at puberty.     

Serum profiles of progesterone, LH, FSH and prolactin immediately preceding induced puberty in gilts

Two experiments were conducted to determine if the secretory patterns of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) and serum concentrations of progesterone change immediately preceding induced puberty in gilts. To help predict when prepubertal gilts would attain puberty, gilts were induced into puberty by relocation from confinement housing to an outdoor lot and exposure to mature boars. In Exp. 1, 17 prepubertal gilts were bled on two successive days from 0800 to 1200 h before relocation and boar exposure and until the second day of estrus or for 8 d in gilts that failed to exhibit estrus. Blood samples were collected from indwelling cannulas at 20-min intervals for 4 h. In Exp. 2, blood samples were collected from 20 prepubertal gilts at 20-min intervals from 0800 to 1200 h and from 2000 to 2400 h until the second day of estrus or for 6 d if the gilt failed to exhibit estrus. In each experiment, 11 gilts exhibited pubertal estrus 3 to 6 d after relocation and boar exposure. When the frequency of LH spikes in each gilt was normalized to the day of her preovulatory surge of LH (d 0), a decline in the frequency of LH secretory spikes was observed as gilts approached puberty. However, neither the average magnitude of LH spikes nor mean LH concentrations were different among these days. Mean serum concentrations, frequency of spikes or average magnitude of secretory spikes of FSH or PRL did not change on the days preceding the preovulatory peak of LH.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of growth rate and onset of boar contact on puberty attainment of replacement gilts raised in Thailand

This study aimed to investigate the influence of growth rate and onset of boar contact on age at first observed estrus of the replacement gilts raised in Thailand. In total, 766 gilts were measured for body weight and backfat thickness prior to insemination. Body weight was further calculated for growth rate. Estrus detection was performed twice a day by back pressure test with an existence of mature boars with high libido. The first date of boar exposure and that of first observed estrus were individually recorded. Due to growth rate, they were classified into three groups: high (>700 g/day), moderate (600–700 g/day), and low (<600 g/day). According to onset of boar contact, the gilts were grouped into two categories: early (<150 days) and late (≥150 days). The results revealed that the gilts expressed first observed estrus, averagely, at age 205.1?±?34.1 days, had a growth rate of 615.5?±?57.6 g/day, and first contact with boars at 160.7?±?19.9 days of age. The gilts with low growth rate expressed first estrus later than those with moderate (208.6?±?2.0 vs 198.0?±?3.2 days, P?=?0.033) and high growth rate (208.6?±?2.0 vs 193.9?±?6.7 days, P?=?0.005) groups. Together with the influence of boar exposure, the gilts contacted boar earlier with high growth rate showed first estrus at age 180.3?±?10.1 days, whereas those with later boar contact with low growth rate showed first estrus at age 197.9?±?3.2 days. In summary, the replacement gilts should have high growth rate and contact boar early to attain puberty faster and possess decent subsequent reproductive performance.     

Effects of adrenalectomy and glucocorticoids on puberty in gilts reared in confinement

The effect of adrenal function and flumethasone (FM, a synthetic glucocorticoid) on induction of puberty in crossbred gilts raised in confinement was examined in two experiments. In Exp. 1, gilts were adrenalectomized (Adx) or subjected to sham adrenalectomy (Sham) between 140 and 160 d of age. Twenty days later indwelling jugular catheters were implanted in Adx, Sham and another group of intact gilts designated as Controls, and the gilts were moved from confinement to outdoor pens and checked daily for estrus with a mature boar. Fewer (P less than .05) Adx (1/11) than Sham (9/14) gilts showed estrus and ovulated by 205 d of age. Response of Control gilts (6/14) was not different from the other groups. Although Adx gilts received 40 mg cortisone acetate and 10 mg deoxycorticosterone acetate daily throughout the experiment, mean plasma glucocorticoids were lower (P less than .05) in Adx (24 +/- 4.7 ng/ml) than in either Sham (47 +/- 8.1 ng/ml) or Control (44 +/- 6.1 ng/ml) gilts. Experiment 2 was conducted to determine whether FM given to Adx gilts immediately after surgery could have inhibited estrus and ovulation. Intact gilts received a total of 27.5 (FM1) or 17.5 (FM2) mg FM over 4 d between 150 and 160 d of age before relocation and boar exposure 20 d later. Control gilts received no injections. Nine of 13 FM-treated but none of the Control gilts showed estrus. It is concluded from these results that the adrenal glands may facilitate the onset of puberty in gilts through increases in glucocorticoid production, but that this is not required for puberty to occur.     

The effect of confinement on days to puberty in gilts

In the late fall and winter of 1982 to 1983, 112 crossbred gilts were used in a factorially arranged experiment to determine the effect of confinement on the age at which a gilt reaches first estrus (puberty). Two environments (confinement and non-confinement) and three ages at movement to non-confinement (100, 140, and 180 d) were studied. No differences were detected (P greater than .05) between confinement and non-confinement in the proportions of gilts reaching puberty by 210 d of age. Gilts were older at puberty (P less than .05) in confinement than in non-confinement (192.0 vs 187.7 d) and had a longer interval (P less than .05) from first boar contact to first estrus (12.1 vs 7.8 d). Age at puberty (192.1 vs 187.0 vs 190.5 d) and the proportion reaching puberty (56.4 vs 45.7 vs 65.8%) were not different (P greater than .05) between age-of-movement groups. However, a higher (P less than .05) proportion of the non-confinement gilts reached puberty within 10 d after the beginning of boar exposure than confinement (44.6 vs 26.8%). Moving gilts from confinement to non-confinement (pasture) at 180 d appeared to be the most effective method tested for inducing puberty in gilts.     

Growth rate and age at boar exposure as factors influencing gilt puberty

The objective of this study was to verify whether pubertal estrus could be influenced by the growth rate and age of gilts at the onset of boar exposure. Gilts (n = 1486) were evaluated according to two groups of age at boar exposure (A = 130-149 d and B = 150-170 d) and three classes of growth rate (Low = 550–649 g/d; Intermediate = 650–725 g/d and High = 726–830 g/d). Gilts of groups A and B were, respectively, 142.6 ± 4.9 and 157.0 ± 5.1 days of age at the onset of boar exposure. Overall, 85% of gilts showed estrus within 40 days of boar exposure. Within group A gilts a higher (P < 0.05) cumulative percentage of estrus within 20 days of stimulation was observed in High than in Intermediate and Low growth rate gilts (59.7% vs. 48.7% vs. 48.2%; P < 0.05). Nevertheless, within group B there was no difference in the percentage of estrus among growth rate classes (63.8% vs. 67.3% vs. 63.7%, P > 0.05). Within group A, puberty was attained earlier in High than in Low growth rate gilts (159.6 vs. 164.8 days). However, age at puberty was not affected by growth rate, when gilts were exposed to boar in an older age (group B). Overall, age at puberty was positively associated with the age at the onset of boar exposure (r = 0.38; P < 0.0001) and the older the gilts were at boar exposure the lower was the interval (r = - 0.19; P < 0.0001) from stimulation to onset of puberty. In conclusion, successful stimulation of puberty can be obtained through an earlier exposure to boars in high growth rate gilts.     

Reproductive Performance of Gilts with Similar Age but with Different Growth Rate at the Onset of Puberty Stimulation

The aim of this study was to evaluate the reproductive performance of gilts that had a similar age but different weights at the onset of puberty stimulation by boar exposure at 144 days. Gilts were divided into two groups according to their lifetime growth rate from birth to approximately 144 days of age. Mean growth rates at this moment were 577 and 724 g/day for group 1 (G1; n = 58) and group 2 (G2; n = 58), respectively. After selection, gilts were weighed at approximately 155, 165 and 175 days of age, on the insemination day and at slaughter. Gilts were inseminated, on average, at 193 days of age and were slaughtered 32 days after insemination, when the number of corpora lutea and embryos were recorded. Higher growth rate gilts (G2) reached puberty earlier (155.3 vs 164.1 days; p < 0.01). More gilts of G2 group attained puberty by 190 days of age (p = 0.004) than G1 gilts (95%; 55/58 vs 76%; 44/58). The anoestrous rate, until 60 days after the onset of boar exposure was higher (p < 0.01) in G1 (19.0%; 11/58) than in G2 (3.4%; 2/58) group. However, there were no differences in the pregnancy rate (90.7 vs 94.5), ovulation rate (15.9 vs 16.5), total embryos (12.9 vs 11.7), viable embryos (12.0 vs 11.1) and embryo survival (73.7% vs 68.5%), between G1 gilts and G2 gilts, respectively (p > 0.05). High growth rate gilts attain puberty earlier and have a lower anoestrous rate than low growth rate gilts.     

The effect of duration of boar exposure on the frequency of gilts reaching first estrus

One-hundred crossbred gilts were used in an experiment that was designed to examine the effects of duration of boar exposure on the proportion of gilts reaching first estrus. Two replicates (summer and fall) of 50 gilts each were randomly assigned, within litter, to one of the following treatments: 1) 30 min of daily boar exposure, 2) 15 min of daily boar exposure, 3) 5 min of daily boar exposure, 4) continuous fence-line boar exposure, plus walked to a neutral pen and exposed to a different boar for 10 to 15 min daily, or 5) continuous fence-line boar exposure. Boar exposure lasted for 30 d. The percentage of gilts exhibiting first estrus by 210 d of age ranged from a high of 65.0 for treatment 4 to a low of 10.0 for treatment 5. Treatments 1, 3 and 4 were greater than treatment 5 (P less than .05), but not different from treatment 2. There were no differences in average age at first estrus. Treatment means for days to puberty after boar exposure were not different (P greater than .05). However, a significant treatment X season interaction occurred. This interaction appears to suggest seasonal trends. These results indicate that treatments 1 and 4 (30 min daily and continuous fence-line boar exposure plus 10 to 15 min, respectively) were the most effective methods tested for the induction of first estrus.     

The effect of intramuscular injections of boar pheromone 5alpha-androstenol on the hormonal regulation of the estrous cycle in hypoosmatic gilts

Until 1999 it was accepted that pheromones act exclusively by stimulating the dendritic receptors present in olfactory epithelium. Cycling gilts with an experimentally-disrupted neural olfactory pathway were used to test the hypothesis that boar pheromone 5alpha-androstenol may affect the secretion of hormones involved in the regulation of the estrous cycle by the humoral pathway. On day 12 of the estrous cycle the nasal cavity of gilts (n=15) was irrigated with zink sulfate solution. From day 16 to 20, the experimental group (n=10) was injected intramuscularly with 5alpha-androstenol (20 microg) twice a day. Blood samples were collected from the jugular vein at 4 h intervals on days 17-21 to estimate plasma concentration of LH, oxytocin, estradiol-17beta, testosterone and progesterone. The experimental group displayed a significantly lower mean concentration of LH than the control animals (P<0.0001). The decrease in concentration of LH was accompanied by the reduction of oxytocin (P<0.001), estradiol-17beta (P<0.001) and testosterone (P<0.01) secretion. These results demonstrated that 5alpha-androstenol influenced hormonal regulation by humoral pathway and might be considered to be the priming pheromone in gilts.     

Effect of treatment with and subsequent withdrawal of exogenous porcine somatotropin on growth and reproductive characteristics of gilts

Two experiments were conducted to examine responses of gilts to treatment with and withdrawal of exogenous porcine somatotropin (PST). In Exp. 1, 36 prepubertal gilts (79.7 +/- .9 kg; 159.1 +/- .7 d) were allotted randomly to receive daily either 0 micrograms PST (C) or 70 micrograms PST/kg initial BW for either 21 (PST-3) or 42 d (PST-6). Gilts were examined for estrus daily by a mature boar starting on d 22 and continuing for up to 50 d. Gilts that expressed estrus were mated and removed from treatment. PST-treated gilts had higher ADG (P less than .01) and lower feed/gain (P less than .02) than C gilts. Following initiation of boar exposure, C gilts (mean interval to estrus = 2.0 d) exhibited estrus earlier than PST-3 (24.8 d) and PST-6 (24.0 d) gilts (P less than .07); however, only two C gilts were observed in estrus compared with six PST-3 and six PST-6 gilts. In Exp. 2, 40 prepubertal gilts (72.6 +/- 1.0 kg; 141.1 +/- .7 d) were allotted randomly to receive daily either 0 mg PST (C) or 5 mg PST for 30 d. On d 31, half the gilts were comingled with unfamiliar penmates and examined for estrus daily by a mature boar for up to 45 d. Estrual gilts were removed from treatment.(ABSTRACT TRUNCATED AT 250 WORDS)