Effect of photoperiod on reproductive activity and hair in mares.

The effects of photoperiod on reproductive activity and hair changes in pony mares were studied in 2 experiments. In experiment I, the effect of a fixed daily photoperiod on the onset of the breeding season was studied in 36 mares from Nov 13, 1973, to June 13, 1974. The 4 treatment groups were as follows: daily photoperiod equivalent to the normal day length (control group); constant light 24 hours a day with no dark (L24:D0 group); 16-hour daily photoperiod with 8 hours of dark (L16:D8 group); and 9-hour daily photoperiod with 15 hours of dark (L9:D15 group). The intervals from beginning of experiment to 1st ovulation of breeding season, to shedding of hair in tufts, and to appearance of a smooth coat were shorter (P less than 0.05) for L16:D8 group (107.1 +/- 11.1, 56.0 +/- 0, and 145.8 +/- 4.0 days, respectively) than for control, L24:D0, and L9:D15 groups and were shorter (P less than 0.05) for L24:D0 group (less than 156.1 +/- 12.2, 99.5 +/- 9.5, and 173.9 +/- 9.9 days, respectively) than for control group (192.1 +/- 3.3, 134.9 +/- 8.9, and 205.0 +/- 0 days, respectively) or L9:D15 group (less than 200.3 +/- 5,8, 150.6 +/- 12.9, and 201.7 +/- 3.3 days, respectively). These intervals were not significantly different between the control group and the L9:D15 group, but fewer (P less than 0.05) mares in the L9:D15 group had at least 1 ovulation by termination of the project. In experiment II, the effect of photoperiod on onset of anestrus was studied in 3 groups of 7 mares each. Mares in group A, as part of a previous experiment, were induced to enter the breeding season earlier than normal by a gradual increase in daily photoperiod beginning on Oct 13, 1972. From Feb 16, 1973, to June 22, 1973, group A mares were maintained at a fixed daily photoperiod of 15 hours 23 minutes. Mares in group B, as part of a previous experiment, were kept under environmental conditions simulating normal conditions in southern Wisconsin. On June 22, 1973 (beginning of the present experiment), the following treatments began: groups A and B were exposed to natural day length. In addition, 7 mares (group C) were allotted from a band of mares that had been exposed to natural day length and were exposed to 15-hour 23-minute daily photoperiod from the beginning of the present experiment (June 22, 1973) to the end (June 22, 1974). The interval to onset of anestrus was longer (P less than 0.05) for group C mares (234.6 +/- 35 days) than for group B mares (133.6 +/- 16.5 days). Significant difference did not exist between group A (144.0 +/- 45.9 days) and group B. A fixed daily photoperiod of 16 or 24 hours induced early onset of the breeding season and early shedding of hair, with development of a smooth coat. A photoperiod of 9 hours retarded the onset of the breeding season. Mares induced to begin the breeding season earlier than normal did not become anestrous earlier than normal. Mares kept on a long daily photoperiod in the fall became anestrous later than normal.     

Effect of photoperiod on gonadotrophin concentrations in domestic turkeys

1. Circulating immunoreactive luteinising hormone (LH) and follicle stimulating hormone (FSH) concentrations have been measured during photoperiodically‐induced changes in the reproductive state of turkeys.

2. In a period of sexual quiescence on short photoperiods (6L : 18D) LH concentrations were higher during the hours of darkness in both sexes.

3. Transfer to long photoperiods (16L : 8D) stimulated a rapid increase in LH and FSH concentrations. This was maintained for between 2 to 3 months when the concentrations of both gonadotrophins decreased as the birds became photorefractory.

4. Return to short photoperiods had no immediate effect on the concentrations of LH and FSH in females. The concentration of LH was increased during the 3rd week of short photoperiods when the hens were moulting.

5. LH concentrations fluctuated during the ovulatory cycle and were highest about 6 h before ovulation.     

光周期对紫花苜蓿SOD、POD活性的影响

研究了8,12和16h不同的光照时间对秋眠型紫花苜蓿品种Vernal的超氧化物歧化酶（SOD）和过氧化物酶（POD）活性的影响。结果表明：Vernal的SOD和POD的活性呈现出8h光照最高,12h次之,16h最低的趋势;同一光周期条件下,SOD、POD的活性随着生长期的延长而升高,说明SOD、POD的活性与光周期有关,短日照可提高SOD、POD的活性,增强其抗逆性。     

不同光照对一化性柞蚕解除滞育的影响

柞蚕蛹感光解除滞育的方法是柞蚕"一化二放"秋柞蚕制种的唯一措施,探明柞蚕蛹感光解除滞育的规律,可为柞蚕种质资源鉴定、保存、开发利用等方面提供技术支撑。     

Effect of dietary selenium and vitamin E on spermatogenic development in boars

An experiment involving a total of 61 crossbred boars evaluated the effects of dietary Se and vitamin E on spermatogenic development at various stages of sexual development and the prostaglandin F2alpha (PGF2alpha) content in the seminal vesicle and prostate glands at 18 mo of age. The experiment from 5.4 to 9 mo of age was conducted as a 2 x 2 factorial in a randomized complete block design. Dietary Se at 0 or .5 ppm was the first factor and vitamin E at 0 or 220 IU/kg diet was the second. From 9 to 18 mo of age, a group of sexually active and inactive boars was a third factor. Treatment diets were fed from weaning (28 d of age) to the end of the experiment. Three boars per treatment group at 5.4 (105 kg BW), 6.2 (130 kg BW), and 9.0 (150 kg BW) mo of age were killed and the testes collected. From 9 to 18 mo of age, three boars from each dietary treatment group were used for semen collection, and another set of three to four boars from each treatment group remained sexually inactive. At 18 mo, both sets of boars were killed and their testes, prostates, and seminal vesicles were collected. The testis at each age was evaluated for sperm reserve numbers and germ and Sertoli cell populations. At 5.4 or 6.2 mo of age, testicular sperm reserves were not affected by dietary Se (P > .15), at 9.0 mo of age there was a trend for a higher (P < .10) number of sperm reserves, and by 18 mo of age the Se-fed boars had higher (P < .01) numbers of sperm reserves. Vitamin E had no effect (P > .15) on testicular sperm reserves at any age period. Boars fed dietary Se had a greater number of Sertoli cells (P < .01) and round spermatids (P < .01) at 6.2 mo of age, but by 18 mo of age the boars fed Se had more Sertoli cells (P < .05), more secondary spermatocytes (P < .01), and more round spermatids (P < .05). Vitamin E did not affect Sertoli or germ cell populations at the various ages. Boars at 18 mo of age had lower PGF2alpha concentrations in the prostate (P < .05) and seminal vesicles (P < .01) when vitamin E was fed, whereas Se had no effect. Sexually active boars had lower PGF2alpha concentrations in the seminal vesicles (P < .01) than sexually inactive boars, but there was no effect (P > .15) of sexual activity on the number of Sertoli cells, primary or secondary spermatocytes, or round spermatids. Our results indicate that Se has a role in establishing the number of boar spermatozoal reserves and Sertoli cells, whereas supplemental vitamin E did not affect these criteria.     

Effect of photoperiod on the mean oviposition time of two breeds of laying hen

1. Oviposition times were recorded for brown and white egg‐laying hybrids under 8, 10, 13 and 18 h photoperiods.

2. Mean oviposition time for both breeds was advanced relative to dusk by approximately 0.5 h for each 1 h extension of photoperiod.

3. Mean oviposition time for the brown egg hybrid was 1.2 to 1.4 h earlier than that of the white egg hybrid under each lighting regimen.

4. A genetic difference in phase setting of the Open Period for Luteinising Hormone (LH) release is the likely reason for the difference in mean time of lay of the two breeds. The difference is possibly one between brown and white hybrids generally, rather than between the particular varieties of hen used in this trial.

5. The proportion of the day in which eggs are laid is shorter under long photoperiods presumably because light at the end of the photoperiod inhibits the pre‐ovulatory surge of LH.     

Effect of photoperiod and temperature on prolactin secretion in ovariectomized gilts

Five ovariectomized (OVX) gilts were placed in each of two chambers at 20 C with a photoperiod of 12 h light and 12 h dark for 8 d (12L:12D). On d 1, blood samples were collected via jugular cannula every 30 min from 0830 to 1630. At 1630, 200 micrograms of thyrotropin releasing hormone (TRH) were injected iv and blood samples taken every 10 min for 1 h and every 30 min for the next 2 h. On d 2, samples were taken every 30 min from 0830 to 0930 and from 1530 to 1630. Temperature was changed to 10 C or 30 C on d 3. Samples were taken from 0830 to 1630 on d 3, 4 and 9. At 1630 on d 9, the TRH challenge was repeated. Mean basal serum concentrations of prolactin (PRL) were similar for all gilts and for all periods. However, serum PRL response (ng PRL X ml-1 X 150 min-1) to TRH increased (P less than .0001) after exposure to 30 C, while exposure to 10 C failed to alter PRL response. In Exp. 2, six ovariectomized gilts were assigned to each chamber. The protocol of Exp. 1 was followed through d 3, except temperature and photoperiod were changed to 10 C and 8L:16D or 30 C and 16L:8D. On d 34 the TRH challenge was repeated. Mean basal serum concentration of PRL was similar for all gilts and all periods. However, simultaneous increases in temperature and photoperiod increased (P less than .005) serum PRL response to TRH, whereas simultaneous decreases in temperature and photoperiod failed to alter PRL response to TRH.     

槲皮素对双酚A致小鼠生精功能障碍的治疗作用

将50只雄性昆明小鼠随机分为5组,A组（n=10）正常喂饲,B、C、D、E组（各10只）小鼠均腹腔注射50mg／kg·d的BPA,1次／d,连续注射7d,构造小鼠睾丸损伤模型,同时C、D、E组分别用100、200、400mg／kg·d浓度的Que灌胃7d,A组和B组给予等量生理盐水。记录小鼠的体征、体质量变化及试验结束时睾丸、附睾和精囊腺的质量;试剂盒检测血清中超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GsH—Px）和丙二醛（MDA）的含量;酶联免疫法测定血清睾酮（T）、黄体生成素（LH）和促性腺激素释放激素（GnRH）的水平;对睾丸组织进行组织学观察。结果显示：D组200mg／kg·d小鼠体质量、各脏器质量均较B组有明显改善（P〈O．05或P〈0．01）,接近A组,C组和E组只有附睾质量变化显著（P〈0．05）;Que各剂量组血清中的SOD、GSH—Px活性均高于BPA组,差异极显著（P〈0．01）,其中D组抗氧化酶的活性最高;MDA测定结果显示,D组明显降低,差异极显著（P〈0．01）,E组也有所降低,差异显著（P〈0．05）;C、D、E组小鼠血清生殖激素水平均有一定程度的恢复,但D组各生殖激素指标均接近A组;组织学观察见各给药组睾丸生精小管生精细胞层数、精子数目均高于B组,尤以D组200mg／kg·d恢复最为明显。结果表明：Que能够促进BPA致小鼠睾丸生精功能障碍后生精功能的恢复,且最佳剂量为200mg／kg·d。     

高钼对小尾寒羊睾丸生精功能和病理损伤作用的研究

2月龄雄性小尾寒羊12只,随机分为3组,Ⅰ组饲喂基础日粮(Mo 5.61 mg/kg),Ⅱ、Ⅲ组饲喂高钼日粮(在基础日粮中分别添加30、60 mg/kg的钼构成).120 d后取睾丸,检测精液品质,以流式细胞术和透射电镜的方法观察睾丸的变化.结果表明,与Ⅰ组相比,Ⅱ、Ⅲ组睾丸指数显著降低(P＜0.01),精子密度和精子活力显著下降(P＜0.01),Ⅱ、Ⅲ组之间差异显著(P＜0.05);Ⅱ、Ⅲ组睾丸细胞G0/G1期显著升高,S期,G2 +M期和增值指数(PI)显著降低(P＜0.05或P＜0.01),Ⅱ、Ⅲ组之间各项指标差异极显著(P＜0.01);Ⅱ、Ⅲ组睾丸细胞线粒体肿胀、空泡化,内质网扩张,胞核染色质边集,精子顶体膜模糊或缺损,Ⅲ组出现核溶解的现象.结论:日粮钼含量≥30 mg/kg可造成小尾寒羊睾丸超微结构损伤,导致精液品质和生精功能下降.     

Effect of season and photoperiod on the time of first postpartum ovulation in Awassi ewes

Seasonal differences in the resumption of postpartum ovarian activity, milk production and periparturient metabolic status were investigated in lactating non-suckling dairy Awassi sheep in two consecutive experiments. In Experiment 1, autumn-lambing (AL, n = 27) and spring-lambing (SL, n = 37) ewes were investigated. Ovarian activity was monitored by means of individual progesterone (P4) profiles from day 5 to day 100 post partum. Most of the AL dams (89%) ovulated till day 35 after parturition and became cyclic thereafter. Incidence of persistent corpus luteum (CLP) and short luteal phases (sCL) was frequent (18% and 29%, respectively) among non-conceiving dams. In contrast, only 24% of the SL ewes ovulated before day 35. P4 levels during the luteal phase were lower in cyclic animals, and the cycle was longer in SL than in AL animals. No CLP or sCL was detected in the spring-lambing group, and 61% of SL ewes remained acyclic till the end of the trial. Lactation length was significantly longer in SL dams than in AL ewes (P = 0.008). According to the plasma metabolites (BHB, NEFA) and metabolic hormones (insulin, IGF-I, thyroxine) examined, negative energy balance did not appear in any of the animals. However, seasonal differences were seen in IGF-I and thyroxine levels, which were higher in the SL dams. In Experiment 2, influence of additional lighting was studied in autumn-lambing ewes. The long-day photoperiod (LD, n = 23) group was exposed to artificial light from sunset till midnight (approx. 16 h light/8 h dark) from some weeks before the expected date of delivery in mid-September until the end of December. The control group (n = 25) experienced only natural daylength. The first postpartum ovulation tended to occur later in the LD animals than in the controls (P = 0.047). The lactation of the LD group tended to be longer (P = 0.061). NEFA, BHB, insulin, IGF-I and thyroxine levels did not differ between the groups. Conclusions: (i) The ovarian function of the Awassi population is seasonal under temperate continental climate conditions. (ii) The first postpartum ovulation of non-suckling, autumn-lambing dams may occur very early, even before the completion of uterine involution. (iii) Additional artificial lighting may delay the time of first postpartum ovulation in AL ewes. (iv) Postpartum negative energy balance is unlikely to occur in dairy Awassi ewes even in high-producing intensive systems.     

光照对非生绒期内蒙古白绒山羊体成分的影响

从体成分的角度研究了光照对内蒙古白绒山羊营养分配的影响。结果表明,光照对体成分有较大影响,体脂肪随着光照时间的减少而增加,长光照、自然光照和短光照条件下绒山羊的体脂肪含量分别为23.6%、15.78%和14.16%,而体蛋白、体水分和体灰分含量则随着光照时间的减少而减少,长光照和自然光照组显著高于短光照组,长光照组和自然光照组差异不显著。证明了光照对绒山羊有调节营养分配的作用,为其在生产实践中的合理应用提供理论依据。     

光周期对不同秋眠型苜蓿光敏色素和内源激素的影响简

 本试验研究了不同光周期对３种秋眠型苜蓿光敏色素和植物体内源激素含量的影响,为揭示苜蓿秋眠性的调控机理提供科学依据。试验采用ＦＱ-ＰＣＲＳＹＢＲ-ＧｒｅｅｎＩ方法,在人工气候室,以美国苜蓿秋眠级标准对照品种Ｎｏｒｓｅｍａｎ（ＦＤ_１,秋眠型苜蓿,秋眠１级）、Ｄｕｐｕｉｌｓ（ＦＤ_５,半秋眠型苜蓿,秋眠５级）和ＣＵＦ１０１（ＦＤ_９,非秋眠型苜蓿,秋眠９级）为材料,设计４个不同的日照长度梯度（７,１０,１３和１６ｈ／ｄ）,对其植株处理３５ｄ,测定叶片中光敏色素（PHYA 、PHYB）ｍＲＮＡ 表达量,采用（ＥＬＩＳＡ）试剂盒法测定内源激素生长素（ＩＡＡ）、脱落酸（ＡＢＡ）、玉米素核苷（ＺＲ）、赤霉酸（ＧＡ_３）的含量。结果表明,３种不同秋眠型紫花苜蓿PHYA 和PHYB 在短日照条件下合成量大,其中以Ｎｏｒｓｅｍａｎ表现最为明显。不同秋眠类型苜蓿叶片中的ＧＡ_３／ＡＢＡ、ＺＲ／ＡＢＡ和ＩＡＡ／ＡＢＡ均随着光照时间延长而增大;短日照条件下３种秋眠型苜蓿ＡＢＡ的合成量均为最大,ＧＡ_３的含量最低,生长严重受到抑制。可能PHYA 和PHYB 直接或间接影响了内源激素ＧＡ３、ＺＲ、ＩＡＡ、ＡＢＡ合成量,进而调控了苜蓿的秋眠。     

The effect of an extended artificial photoperiod and gonadotrophin-releasing hormone infusions in inducing fertile oestrus in anoestrous mares

The occurrence of fertile oestrus early in the breeding season is of paramount importance to the Thoroughbred industry to facilitate early conception. This paper compares 2 techniques for inducing fertile oestrus in anoestrous mares using either an extended photoperiod alone or together with gonadotrophin-releasing hormone (GnRH) infusions. Eleven mares were placed under conditions of 16 h light and 8 h darkness and 5 of these were implanted with osmotic minipumps delivering approximately 100 ng GnRH/kg/h for 28 days (treated mares). The treated mares ovulated 27.7 days earlier than and conceived 32 days earlier than the 6 mares not given GnRH. GnRH-induced ovulations were followed by a competent luteal phase. The combination of GnRH pumps implanted 2 weeks before commencement of service together with extended photoperiod from July 1 has promise in assisting the stud breeder to improve reproductive efficiency on commercial stud farms.     

LHRH and beta-endorphin in the hypothalamus of the ram in relation to photoperiod and reproductive activity

The regional distribution and relative concentrations of LHRH and beta-endorphin immunoreactivity in the hypothalamus were compared in sexually active and sexually inactive Soay rams. LHRH was localized principally in the medial basal hypothalamus and median eminence with lower concentrations in the anterior hypothalamus and preoptic area. beta-endorphin immunoreactivity was also found in highest concentrations in these regions but was more widely distributed into the rostral, dorsal and lateral parts of the hypothalamus. LHRH content in the medial basal hypothalamus was significantly lower in the sexually active rams compared to inactive rams while there was no difference in beta-endorphin immunoreactivity content between the two groups. Gel filtration chromatography of hypothalamic extracts revealed that the beta-endorphin immunoreactivity was due to both beta-lipotropin and beta-endorphin; the ratio of beta-endorphin: beta-lipotropin tended to be less in the sexually active rams than in the sexually inactive rams. The results are consistent with the hypothesis that beta-endorphin is a physiologically important endogenous opioid involved in the modulation of LHRH secretion.     

Effect of fan induced photoperiod on live performance and yield of male broiler chickens

Increasing broiler house size and ventilation capacity has resulted in increased light ingress through ventilation system components. Light ingress may alter the effective photoperiod for broiler chickens and create local increases in light intensity. This study examined live performance and processing yields in male broilers reared to 63 d of age exposed to either a constant light intensity of 2.5 lx for 18L:6D or a variable light intensity to mimic light ingress through tunnel fans. Body weight, body weight gain, and mortality were not different between treatments. Feed conversion ratio and feed consumption were significantly increased for the variable light treatment, with a difference of 0.06 g feed:g gain (P = 0.01) and 228 g/bird (P = 0.02), respectively. The data herein illustrate the need to mitigate light ingress through ventilation system components to improve live performance in broilers.     

Effect of photoperiod on milk yield and quality, and reproduction in dairy goats

The objective of this study was to examine the effect of long day photoperiod (LDPP) on milk production and reproduction in milk goats. A total of 79 goats were randomly assigned to three treatment groups blocked by day of kidding. Group 1 (Gr1, n = 26) was subjected to natural photoperiod from January 6 to December 5. Group 2 (Gr2, n = 24) was subjected to LDPP (20 h light, 4 h dark) from June 22 to December 5. Group 3 (Gr3, n = 29) was subjected to LDPP from January 6 to December 6. Weekly milk weights and samples were collected for fat, protein and somatic cell count (SCC) determinations. Blood serum was harvested for progesterone (P4) determination. Results indicated a significant effect (p < 0.001) between treatments for body weight changes, feed intake and milk yield. Both light treated groups had a significantly higher (p < 0.001) average daily milk output for the entire lactation period than the control group (G1, 2.193 kg/day; G2, 2.517 kg/day; G3, 2.305 kg/day). Milk fat for the overall lactation was significantly higher in Gr3 (+ 0.19 g/100 ml) than for Gr2 (+ 0.06 g/100 ml) when compared to the control group (x g/100 ml) under natural photoperiod. Somatic cell counts throughout lactation were significantly (p < 0.001) lower for Gr2 (1.70 million/ml) and higher for Gr3 (2.03 million/ml), with the control group (Gr1) having an intermediate level (1.96 million/ml). Progesterone levels between June 9 and August 30 indicated that 27%, 48% and 63% of the animals had P4 levels in excess of 1.0 ng/ml serum for Gr1, Gr2 and Gr3, respectively. Pregnancy diagnosis by ultrasound in December revealed that a high number of does in the light treated groups (10 of 37) were pseudo-pregnant when compared with the control group (1 of 21). Although light appeared to be effective in increasing milk production, further investigations are needed to evaluate the effect of LDPP on pseudo-pregnancy in dairy goats.