不同蛋白水平的缺硒日粮对仔鸡生长及发病死亡的影响

用1日龄Hubbard肉用仔鸡,喂给缺硒日粮,比较在不同蛋白水平下,仔鸡生长及死亡的差别。试验分五个组,三个缺硒组(含硒0.01ppm),每组24只鸡。两个补硒组(0.15ppm),每组16只鸡。基础日粮用黑龙江省产的低硒玉米(0.003ppm)和豆饼(0.017ppm)配成。日粮的蛋白水平用豆饼和玉米的百分比不同来调正。三个缺硒组的蛋白水平分别为22.8、19.3及15.8％。补硒的两个组各为19.3和15.8％。试验期30天。结果表明,缺硒高蛋白组仔鸡开始死亡日龄早,并且死亡率高。蛋白水平为22.8％和19.3％的两组,仔鸡从17日龄开始死亡,而15.8％蛋白组从24日龄才开始死亡。三个组24日龄的死亡率分别为79,58,及21％。在30日龄试验结束时,死亡率分别为96、92及67％。蛋白水平不同,仔鸡增重有明显差别。蛋白水平为22.8％和19.3％的两组仔鸡,10日龄的平均增重比15.8％蛋白组分别提高54％和45％(P<0.01)。仔鸡的血、肝、胰、肌肉的含硒量及全血谷胱甘肽过氧化物酶活性随日粮补硒而提高。     

缺硒对鸡胰腺影响的病理组织学观察

用1日龄来航公雏,进行两次试验。第一次试验,将180只雏鸡按体重平均分为两组,每组90只。试验组喂低硒基础日粮(含硒0.01ppm),对照组在基础日粮中补硒至0.20ppm。试验于6、12、18、24、30日龄时分批进行剖检。每次随机从各组取6只做胰腺的病理组织学观察。 第二次试验,将275只雏鸡按体重平均分成5组,每组55只,日粮含硒水平为0.01ppm、0.025ppm、0.05ppm、0.10ppm、0.20ppm。试验于39日龄时随机从每组取5只进行胰腺的病理组织学观察。 结果,低硒组6日龄时,胰腺腺泡上皮细胞胞浆内出现空泡,12日龄时多数与6日龄的变化几乎相似;18日龄时,腺泡上皮细胞胞浆内出现玻璃小体,并有腺泡轻度萎缩;24日龄时胰腺组织的实质内空泡剧增,呈蜂窝状,部分区域的腺泡萎缩,间质开始纤维化;30日龄时胰腺组织的部分区域出现纤维化;39日龄时日粮硒水平0.01ppm组胰腺组织大部分区域出现纤维化。日粮硒水平0.025及0.05ppm组胰腺组织的部分腺泡严重萎缩或轻度纤维化。日粮硒水平0.10ppm组胰腺组织轻度纤维化或腺泡萎缩。两次试验只有0.20ppm组,除个别胰腺实质中出现少量的空泡外,其余未见异常变化。作者初步认为,鸡日粮中硒的含量以0.15～0.20ppm为适宜。     

鸡缺硒的组织病理学考察

将2日龄洛克鸡分成3组。第1组喂一种缺硒的天然日粮(含0.0065ppm硒);第2组补充维生素E(100Iu/公斤日粮);第3组添加0.2ppm硒,试验7周。在3周龄时表现缺硒症状。病理学检查说明有胰腺的变性、坏死、萎缩和纤维变性,皮肤下有含大量蓝     

动物对不同化合态硒的利用率

近二十年来的研究表明,硒已被公认为动物生命活动所必需的微量元素之一。研究发现动物的白肌病、雏鸡渗出性素质及营养性肝坏死等病与动物饲料缺硒有关。饲养标准规定,饲料含硒量为0.10ppm,而有些饲粮原料含硒低于0.1ppm,所以要在日粮中添加硒化合物。通常以亚硒酸钠的形     

含硒矿物质添加剂喂猪的试验研究

科学家们研究证实,克山病、大骨节病、癌肿、生育及视觉障碍、畜禽白肌病等与机体缺硒密切相关,补硒能增强机体免疫和抗病力。据国外研究,健康猪肝应含硒1.82ppm±0.47,病猪肝硒为0.2ppm±0.05。而兰州兽医研究所翟旭久等报道,我国猪肝含硒量,平均为0.67ppm,云南猪则为0.73ppm。我国云南省普遍缺硒,该所苏琪等报道,生长猪日粮含硒量为0.3ppm时,日增重可比含硒0.01ppm的对照组提高26.7％,血硒量增加12.6倍。     

缺硒对幼年公猪生殖器官发育及精子发生影响的初步研究

为进一步探索硒在公猪繁殖中的确切作用,本试验观察了11头缺硒的(日粮的硒水平为0.01ppm)及8头补硒(日粮的硒水平为0.26ppm)的幼年公猪的生殖器官。观察到缺硒组睾丸、附睾、尿道球腺、精囊腺及前列腺的重量(克/每公斤体重)分别是:1.94、0.38、0.31、0.22及0.04,补硒组相应的各生殖器官的重量是:1.78、0.44、0.44、0.41及0.05,两组精囊腺重量差异显著。观察到7头缺硒组猪的曲精细管的生殖细胞层内有很多大小不一的空泡。并且,附睾尾的附睾管外径及附睾头和附睾尾的附睾管上皮细胞高度,都是补硒组显著比缺硒组高。缺硒组猪附睾尾精浆中精子密度比补硒组低,活率也较低、头部及尾部畸形率都较高,两组精子的尾部畸形率差异显著。测定了各试验猪睾丸及副性腺的硒含量,缺硒组猪的睾丸、尿道球腺、精囊腺及前列腺的硒含量(鲜样重,ppm)是:0.115、0.015、0.030及0.028,补硒组相应的硒含量为:0.222、0.069、0.114及0.118,两组副性腺的硒含量差异非常显著。     

AA肉鸡预防接种暴发缺硒症

全国已查明从黑龙江到云南存在一个缺硒带,其中以黑龙江省最为严重。我场地处本省严重缺硒地区,其日粮含硒<0.02ppm,还不到肉鸡需要量为同粮中0.2ppm 的1/10。这样,我们采取从出壳3日龄的苗雏开始饮     

钙磷水平对猪利用硒的影响

1982年以前,一致认为猪日粮添加0.1ppm的硒(每吨全价饲料含硒90.7mg)是合理的。但是1982年美国食品和药物管理局规定,体重为50磅以下的猪的日粮中添加0.3ppm的硒。许多研究证明,0.3ppm的硒满足了体重在50磅以下的猪最小需要量。同时还表明体重在50磅以下猪的商品饲料中也应该添加0.3     

对一起雏鸡白肌病的治疗观察

鸡渗出性素质病也称鸡白肌病,是日粮中缺乏硒—维生素E引起的一种代谢病,其死亡率不亚于某些传染病。我县属严重缺硒区,部分饲料含硒量的测定结果是:硒平均值为0.019ppm,仅为正常值0.1～0.3ppm的6.3～19％。这就容易导致畜禽缺硒病的发生,近年来,我县犊牛白肌病时有发生。     

奶山羊缺硒病的实验研究

本文分别以低硒日粮和加硒日粮喂饲实验母奶山羊,并对实验母羊后代肌肉注射0和0.2mg/kg体重的亚硒酸钠,进行缺硒病研究。结果表明,母羊和羔羊对低硒营养均有明显的应答反应。应用低硒日粮喂饲奶山羊60天以后可引起发病,母羊和羔羊的发病率分别为50％和85.7％,死亡率为50％和71.4％。被检的17种器官组织含硒水平的组间比较均呈显著差异(P<0.05、0.01或0.001)。血硒和被毛硒水平的变化出现较早,其测定结果可作为奶山羊缺硒病的早期诊断指标。     

生长猪对微量元素硒需要量的初步研究

<正> 硒是动物营养所必需的微量元素,缺硒不但引起人畜发生一系列营养疾病,如人的克山病,幼畜的白肌病以及人畜心脏,肝脏等病变,而且影响家畜的发育,繁殖等,对畜禽生产力危害甚为严重,所以近些年来硒的营养作用在国内外引起了普遍注意。     

Long-term effects of dietary organic and inorganic selenium sources and levels on reproducing sows and their progeny

An experiment evaluated the effects of feeding either a basal non-Se-fortified diet, two Se sources (organic or inorganic) each providing 0.15 and 0.30 ppm Se, or their combination (each providing 0.15 ppm Se) on gilt growth and sow reproductive performance. The experiment was a 2 x 2 + 2 factorial conducted in a randomized complete block design in three replicates. One hundred twenty-six crossbred gilts were started on one of the six treatment diets at 27.6 kg BW. During the grower phase, animals were bled at 30-d intervals with three gilts killed per treatment at 115 kg BW for tissue Se analysis. Fifteen gilts per treatment were bred at 8 mo of age and were continued on their treatment diets for four parities. Sow serum collected within parity was analyzed for Se and glutathione peroxidase (GSH-Px) activity. Tissue Se was determined from five 0-d-old pigs per treatment from fourth-parity sows. Three sows per treatment were killed after the fourth parity for tissue Se analysis. Similar treatment performance responses occurred from 27 to 115 kg BW. Serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased for both Se sources to 0.30 ppm Se during the grower and reproductive periods. Serum Se and GSH-Px activity decreased from 70 to 110 d postcoitum in all treatment groups, but increased at weaning (P < 0.01) in the Se-fortified groups. The number of pigs born (total, live) increased (P < 0.05) with the 0.15 ppm Se level for both Se sources. Tissue and total body Se content of 0-d-old pigs increased with Se level (P < 0.01) and also when the organic Se source (P < 0.01) was fed to the sow. When sows were fed either Se source, pig serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased at weaning. Colostrum and milk Se concentrations increased (P < 0.01) with Se level for both Se sources, but were substantially greater (P < 0.01) when sows were fed organic Se. The combination of Se sources had sow milk and tissue Se values that were similar to those of sows milk and fed 0.15 ppm organic Se. The fourth-parity sows had greater tissue Se concentrations when organic Se level was increased (P < 0.01), more so than when sows were fed inorganic Se. These results suggest that both Se sources resulted in similar sow reproductive performances at 0.15 ppm Se, but sows fed the organic Se source had a greater transfer of Se to the neonate, colostrum, milk, weaned pig, and sow tissues than sows fed inorganic Se.     

Comparative effects of high dietary levels of organic and inorganic selenium on selenium toxicity of growing-finishing pigs

This experiment evaluated the effect of high dietary Se levels using organic or inorganic Se on the selenosis responses in growing-finishing swine. A 2 x 4 factorial arrangement of treatments in a randomized complete block design was conducted in two replicates. Sodium selenite or Se-enriched yeast was added at 5, 10, 15, or 20 ppm Se to corn-soybean meal diets. A basal diet without added Se was a ninth treatment group. Ninety crossbred barrows initially averaging 24.7 kg BW were allotted at five pigs per pen. Pigs were bled at 3-wk intervals and plasma Se, glutathione peroxidase (GSH-Px) activity, glutamic oxalacetic transaminase (PGOT), hemoglobin, packed cell volume, and blood cell Se concentration were measured. After 12 wk, pigs were killed and various tissues and bile were collected for Se analyses. Pig body weights, daily gains, and feed intakes were similar for both Se sources when provided at < or = 5 ppm Se, but each measurement declined in a different manner for each Se source as the dietary Se level increased. The decline was more rapid when the inorganic rather than organic Se source was fed, resulting in interaction responses (P < 0.01). Hair loss (alopecia) and separation of the hoof at the coronary band site occurred at > or = 10 ppm inorganic Se but at > or = 15 ppm organic Se level. Plasma GSH-Px activity increased (P < 0.01) when high dietary Se levels of either Se source was fed. Plasma and blood cell Se increased at each period as dietary Se level increased (P < 0.01) and was greater when organic Se was provided (P < 0.05). Blood cell Se concentration reached a plateau when inorganic Se, but not when organic Se, was fed and increased as the experiment progressed. This resulted in a three-way interaction (P < 0.01). Plasma GOT activity at the 12-wk period was elevated when inorganic Se was provided at > or = 15 ppm Se but not when organic Se was fed, resulting in an interaction (P < 0.05). Tissue Se concentrations increased as dietary Se level increased and when organic Se was provided, resulting in interaction responses (P < 0.05). Bile was a yellow color when the basal diet was fed but was dark brown at > 10 ppm inorganic Se and at 20 ppm when organic Se was provided. Bile Se increased as dietary Se level increased (P < 0.01). These results suggest that dietary Se from inorganic or organic sources was toxic at > or = 5 ppm Se, but subsequent selenosis effects were more severe and occurred sooner when sodium selenite was the Se source.     

Prolonged feeding of high dietary levels of organic and inorganic selenium to gilts from 25 kg body weight through one parity

An experiment evaluated the selenosis effects from feeding high dietary Se levels of organic or inorganic Se sources to growing gilts with the dietary treatments continued through a reproductive cycle. A total of 88 gilts were allotted at 25 kg BW to two replicates in a 2 x 4 factorial arrangement in a randomized complete block design. Inorganic Se (sodium selenite) or organic (Se-enriched yeast) Se were added to diets at 0.3, 3, 7, or 10 ppm Se. At 105 kg BW, four gilts per treatment were killed and livers collected for Se analysis. At 8 mo of age, three gilts from each treatment group were bred and fed their treatment diet, with subsequent reproductive performance and selenosis effects evaluated. Serum collected at various intervals in gilts, sows, and progeny measured glutathione peroxidase activity and Se concentrations. Sow colostrum and milk was analyzed for their Se concentrations. Three pigs per treatment were killed before colostrum consumption and at weaning (14 d) and tissue collected for Se analysis. Gilt gains (P < 0.01) and feed intakes (P < 0.05) declined during the grower period as dietary Se level increased for both Se sources. Serum and liver Se concentrations increased as dietary Se level increased and was higher when organic Se was fed (P < 0.01). Sows fed dietary Se levels at > 7 ppm had lower gestation weights (P < 0.05) and lower lactation feed intakes (P < 0.05). As Se level increased, sows fed organic Se had a lower number of live pigs born (P < 0.05) and weaned fewer pigs (P < 0.05) with lower litter gains (P < 0.05) than did sows fed inorganic Se. Colostrum and milk Se concentrations increased as dietary Se levels increased particularly when organic Se was fed (P < 0.01). Neonatal and weanling pig tissue Se and serum Se concentrations increased as dietary Se level increased and when organic Se was fed, resulting in interaction responses (P < 0.01). Pigs nursing sows fed > 7 ppm inorganic Se had hoof separation and alopecia, with the severity being greater when sows were fed the inorganic Se source. These results suggest that both the organic and inorganic Se sources were toxic when fed at 7 to 10 ppm for a prolonged period, but organic Se seemed to express the selenotic effects more on reproductive performance, whereas inorganic Se was more detrimental during lactation.     

Effect of grazing pasture with a low selenium content on the concentrations of triiodothyronine and thyroxine in serum, and GSH-Px activity in erythrocytes in cows in Chile

AIM: To determine the effect of grazing pasture that had a low selenium (Se) concentration on serum concentrations of triiodothyronine (T3) and thyroxine (T4), and erythrocyte glutathione peroxidase (GSH-Px) activity in dairy cows. METHODS: Forty pregnant Friesian cows were grazed on pasture that contained 0.03-0.04 ppm Se on a dry matter (DM) basis. Two months before parturition, 20 cows were randomly selected and treated with 1 mg Se/kg bodyweight subcutaneously, as barium selenate (Group Se-S). The other group (Se-D) was not supplemented. Blood samples were taken before supplementation (-60 days) and 30, 60, 90, 180 and 270 days after parturition, for determination of concentrations of T3 and T4 in serum, and GSH-Px activity in erythrocytes. RESULTS: Erythrocyte GSH-Px activity in the Se-D group was <60 U/g haemoglobin (Hb) throughout the experiment. Supplementation increased (p<0.05) activities to >130 U/g Hb throughout lactation. Mean serum concentrations of T4 in Se-D and Se-S cows increased from 23.7 (SEM 0.7) and 23.4 (SEM 0.8) nmol/L, respectively, in the prepartum period to 69.6 (SEM 0.1) and 67.6 (SEM 0.2) nmol/L, respectively, at 180 days of lactation (p<0.01), and no effect of Se supplementation was evident. Serum concentrations of T3 in Se-D cows decreased (p<0.05) from 1.6 (SEM 0.1) nmol/L prepartum to 1.0 (SEM 0.2) nmol/L at the beginning of lactation, and remained lower (p<0.05) than those in the Se-S cows which did not decrease after calving and ranged from 1.9 (SEM 0.1) to 2.4 (SEM 0.2) nmol/L throughout lactation. CONCLUSIONS: Serum T3 concentrations decreased during early lactation in unsupplemented cows grazing pastures low in Se (0.03-0.04 ppm) and both serum T3 and erythrocyte GSHPx activities were consistently lower throughout lactation compared with Se-supplemented cows. Se supplementation had no effect on serum T4 concentrations.     

Effect of dietary selenium source, level, and pig hair color on various selenium indices

The first experiment evaluated the effects of feeding various levels of Se, two Se sources, and hair color on selenosis responses in growing-finishing pigs. The study conducted in two replicates was a 2 x 6 x 2 factorial arrangement in a split-plot design. Sodium selenite and Se-enriched yeast added at 0.3, 1, 3, 5, 7, and 10 ppm Se served as the main plot and pig hair color as the subplot. A total of 96 crossbred pigs were allotted and fed their treatment diets for a 12-wk period. White and dark (red or black) hair samples were collected from the dorsal-midline at the 4-, 8-, and 12-wk periods from one pig of each hair color from each treatment pen. Lower pig weights (P < 0.10) and daily gains (P < 0.05) occurred as dietary Se level increased when pigs were fed either Se source. Selenosis responses were somewhat more severe, when the inorganic Se source was fed. Alopecia and hoof separation were encountered after the 8-wk period when pigs were fed inorganic rather than organic Se. Plasma Se increased as dietary level increased (P < 0.01), when organic Se was provided (P < 0.01), and was higher (P < 0.05) when pigs were white-haired. A time x hair color x dietary Se level interaction (P < 0.05) occurred, in which hair Se concentration was higher in dark- than in white-colored pigs and increased as dietary Se level increased as the experiment progressed. The correlation coefficient between dietary Se level and hair Se concentration averaged 0.90 (P < 0.01). Cysteine was the amino acid in the highest concentration in hair, but this and other amino acids were not affected by Se level, Se source, or hair color. A second experiment was a 3 x 6 factorial arrangement in a split-plot design with three 9-mo-old gilts from each of the Yorkshire, Duroc, and Hampshire breeds to determine whether hair Se concentration differed by body location and breed. Hair samples were collected from the shoulder, back, rump, front-leg, belly, and hind-leg areas. Hair Se concentration was higher in red- and white-haired pigs and lower in black-haired gilts (P < 0.01). Higher hair Se concentrations (P < 0.05) occurred from the lower than from the upper body areas. Our results suggest that selenosis occurs at dietary levels > 5 ppm and that white-haired pigs exhibit alopecia sooner than dark-haired pigs. No difference in hair Se concentration occurred when diets were < 1 ppm Se, but as dietary Se level increased dark-haired pigs retained more Se in their hair than white-haired pigs.     

雏鹅实验性缺硒病及高锌对缺硒影响的病理学研究

１００只一日龄雅安本地白鹅随机分三组，分别喂给低Ｓｅ（含Ｓｅ０．０３１６ｐｐｍ）、低Ｓｅ高Ｚｎ（含Ｓｅ０．３１６ｐｐｍ，Ｚｎ１５００ｐｐｍ）和补Ｓｅ（含Ｓｅ０．０３１６ｐｐｍ＋０．３ｐｐｍ）饲粮，饲喂８周。低Ｓｅ组和低Ｓｅ高Ｚｎ组于第３周至第６周发病、死亡高峰。临诊症状表现为精神沉郁、食欲降低、腹泻、脱水和生长缓慢。特征性的损害为肌胃和骨骼肌变性、坏死和钙化；胰腺萎缩、变性、坏死和纤维化；淋巴免疫     

Comparative responses to sodium selenite and organic selenium supplements in Belgian Blue cows and calves

Belgian Blue (BB) beef cattle is particularly prone to selenium (Se) deficiency due to the poor Se content of soil and roughages on rearing farms and the higher requirements of this hypermuscled breed. The goal of this trial was to compare the effects of different forms and concentrations of Se supplementation on Se status, health and performance in 60 pregnant Se-deficient BB cows. Cows were allocated to 3 experimental groups receiving selenized-yeast at 0.5 ppm Se on total ration (Y–Se 0.5), Na–selenite at 0.5 ppm Se on total ration (Na–Se 0.5) and Na–selenite at 0.1 ppm Se on total ration (Na–Se 0.1), respectively. Cows were supplemented from 2 months before calving until 2 months after calving. Data on performance, health and Se status of the dams and their calves were analyzed using a linear model, least squares means and logistic regression. At the end of the study, plasmatic Se (pSe) was significantly higher (P < 0.01) in cows receiving Y–Se than in cows from other groups. Glutathion-peroxidase in erythrocytes (GSH-pxe) was higher in Y–Se and Na–Se 0.5 than Na–Se 0.1 group (P < 0.01). Se content in colostrum and milk was significantly higher (P < 0.01) in Y–Se than other groups. At birth, Se status of calves from group Y–Se was significantly higher than those of other groups (P < 0.01). Plasmatic Se in calves remained higher for 75 days after birth in Y–Se compared to other groups (P < 0.01). Diarrhoea was the most commonly observed disease in the calves and, during the first 15 days of life, diarrhoea occurred in 6%, 21% and 35% of calves from groups Y–Se, Na–Se 0.5 and Na–Se 0.1, respectively. Over the whole 75 days trial period, incidence of diarrhoea was 19, 29 and 65%, respectively. Average daily gain (ADG) in calves born from Y–Se group of cows tended to be higher than in Na–Se 0.5 (P = 0.06) and Na–Se 0.1 (P < 0.05) but there was no difference between Na–Se 0.5 and Na–Se 0.1 (P > 0.1). At the same dosage, Y–Se conferred better Se status in both dams and their calves than did Na–Se. Requirement of 0.1 ppm Se seems to be insufficient in BB to optimise health and performance. Regarding health status and ADG in calves, Y–Se seems also to result in better performance.     

Effect of grazing pasture with a low selenium content on the concentrations of triiodothyronine and thyroxine in serum,and GSH-Px activity in erythrocytes in cows in Chile

AIM: To determine the effect of grazing pasture that had a low selenium (Se) concentration on serum concentrations of tri iodothyronine (T₃) and thyroxine (T₄), and erythrocyte glutathione peroxidase (GSH-Px) activity in dairy cows.

METHODS: Forty pregnant Friesian cows were grazed on pasture that contained 0.03–0.04 ppm Se on a dry matter (DM) basis. Two months before parturition, 20 cows were randomly selected and treated with 1 mg Se/kg bodyweight subcutaneously, as barium selenate (Group Se-S). The other group (Se-D) was not supplemented. Blood samples were taken before supplementation (-60 days) and 30, 60, 90, 180 and 270 days after parturition, for determination of concentrations of T₃ and T₄ in serum, and GSH-Px activity in erythrocytes.

RESULTS: Erythrocyte GSH-Px activity in the Se-D group was >60 U/g haemoglobin (Hb) throughout the experiment. Supplementation increased (p>0.05) activities to >130 U/g Hb throughout lactation. Mean serum concentrations of T₄ in Se-D and Se-S cows increased from 23.7 (SEM 0.7) and 23.4 (SEM 0.8) nmol/L, respectively, in the prepartum period to 69.6 (SEM 0.1) and 67.6 (SEM 0.2) nmol/L, respectively, at 180 days of lactation (p>0.01), and no effect of Se supplementation was evident. Serum concentrations of T₃ in Se-D cows decreased (p>0.05) from 1.6 (SEM 0.1) nmol/L prepartum to 1.0 (SEM 0.2) nmol/L at the beginning of lactation, and remained lower (p>0.05) than those in the Se-S cows which did not decrease after calving and ranged from 1.9 (SEM 0.1) to 2.4 (SEM 0.2) nmol/L throughout lactation.

CONCLUSIONS: Serum T₃ concentrations decreased during early lactation in unsupplemented cows grazing pastures low in Se (0.03–0.04 ppm) and both serum T₃ and erythrocyte GSH-Px activities were consistently lower throughout lactation compared with Se-supplemented cows. Se supplementation had no effect on serum T₄ concentrations.     

Effects of selenium supplementation on plasma progesterone concentrations in pregnant heifers

It is known that selenium (Se) has various functions in animals. Many investigations on the biochemical and physiological effects of Se have been previously reported; however, the detailed function of Se in reproduction is not yet clear. We proposed the possibility that Se plays a notable role in progesterone production. The aim of this study was to clarify the effects of Se supplementation on progesterone levels of pregnant Holstein heifers. Eight Holstein heifers (?Se) were fed basal diet (containing 0.022 ppm of Se) throughout the experiment. While a 0.3 ppm diet of Se (sodium selenite) was fed to another seven animals (+Se) with basal diet. Blood sampling was carried out every week. Plasma Se concentrations were higher in Se‐supplemented cows compared with controls (?Se) (P < 0.01) throughout the experiment. Se supplementation increased plasma progesterone in the 29–39 weeks of pregnancy from 4.98 ± 0.64 to 6.86 ± 0.49 ng/mL on average (P < 0.05). The present findings suggest that Se contributes to maintaining the function of the corpus luteum and/or placenta in the latter period of pregnancy.