Impact of manganese amino acid complex on tissue-specific trace mineral distribution and corpus luteum function in gilts

Functional corpora lutea (CL) are required for pregnancy establishment and gestational maintenance in swine, and CL function is susceptible to environmental influences. Manganese (Mn) could be critical in regulating CL function since it is a component of the antioxidant enzyme Mn superoxide dismutase (MnSOD) as well as enzymes involved in cholesterol and steroid hormone synthesis. We hypothesized that a more bioavailable dietary Mn source would increase Mn content in the CL thereby influencing luteal function during the mid-luteal phase of the estrous cycle. Postpubertal gilts (n = 32) were assigned to one of four gestation diets. The control diet (CON) met or exceeded National Research Council (2012) requirements and was formulated to contain 20 parts per million (ppm) of added Mn in the form of Mn sulfate. Three additional diets included 20 (treatment [TRT]1), 40 (TRT2), or 60 (TRT3) ppm of added Mn from a Mn–amino acid complex (Availa-Mn; Zinpro Corporation) instead of Mn sulfate. Dietary treatment began at estrus synchronization onset and continued through 12 days post estrus (dpe) of the ensuing estrous cycle. Blood samples were collected at estrus onset, which was assigned as 0 dpe, as well as 4, 8, and 12 dpe. Gilts were euthanized and tissues were collected at 12 dpe. Serum progesterone (P₄) increased (P < 0.01) from 0 to 12 dpe but was unaffected by dietary treatment (P = 0.15) and there was no effect of the interaction between day and treatment (P = 0.85). Luteal Mn content increased (P ≤ 0.05) by 19%, 21%, and 24% in gilts fed TRT1, TRT2, and TRT3, respectively, compared to CON. Luteal P₄ concentrations decreased (P = 0.03) 25%, 26%, and 32% in gilts fed TRT1, TRT2, and TRT3, respectively, compared to CON. Relative to CON gilts, CL calcium content decreased (P = 0.02) by 36%, 24%, and 34% for TRT1, TRT2, and TRT3 gilts, respectively. Collectively, these data support the hypothesis that feeding a more bioavailable Mn source increases Mn accumulation in CL tissue. If and how this influences CL function may be related to altered luteal P₄ concentrations.     

Colour‐Doppler ultrasound imaging as a laparoscopy substitute to count corpora lutea in superovulated sheep

This study evaluated colour‐Doppler ultrasound imaging (UI) as a substitute for laparoscopy to count the corpora lutea (CL) in superovulated sheep. Twenty‐five Santa Ines ewes were superovulated three times at 21‐day intervals. Corpora lutea were counted by colour‐Doppler UI (CL_DOPPLER) 6 days after each superovulation and confirmed by laparoscopy (CL_LAP) 12 hr later. The mean number of CL was similar for both techniques (2.1 ± 2.5 vs. 2.1 ± 2.7 for CL_DOPPLER and CL_LAP, respectively) with a significant positive correlation (r = .94; r²=.89). Colour‐Doppler UI effectively evaluated the ovarian response in superovulated ewes and efficiently identified animals that did not respond to superovulation.     

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.     

Age‐related changes in the bovine corpus luteum function and progesterone secretion

Decreased fertility associated with maternal ageing is a well‐known critical problem, and progesterone (P4) concentration decreases during the menopause transition in women. The corpus luteum (CL) secretes P4, thereby supporting the implantation and maintenance of pregnancy. It is proposed that a bovine model is suitable for studying age‐associated decline of fertility in women because the physiology of cows is similar to that of women and cows have a greater longevity compared with other animal models. Thus, we investigated the age‐dependent qualitative changes and inflammatory responses in the bovine CL. In vivo experiment: Cows were divided into three groups, namely, young (mean age: 34.8 months), middle (80.1 months) and aged (188.9 months). Blood samples were collected on days 7 and 12 during the estrous cycle. In vitro experiments: Cows were divided into young (mean age: 27.6 months) and aged (183.1 months). The CL tissues of these groups were collected from a local slaughterhouse and used for tissue culture experiments. An in vivo experiment, plasma P4 concentration in aged cows was significantly lower than that in young cows, whereas no difference was found regarding the area of CL. An in vitro examination in the bovine CL tissues showed that the luteal P4 concentration, P4 secretion, and mRNA expression of StAR and 3β‐HSD were lower in aged cows compared with young cows, especially in the early luteal phase. However, no differences were detected in the mRNA expression of inflammation‐ and senescence‐related factors and inflammatory responses to lipopolysaccharides between the CL tissues from young and aged cows, indicating that an age‐dependent increase in inflammation is not involved in the luteal function. P4 production and secretion from the bovine CL diminish in old cows, especially during the early luteal phase, suggesting that senescence may affect the luteal function in cows.     

Accessory corpora lutea formation in pregnant Hokkaido sika deer (Cervus nippon yesoensis) investigated by examination of ovarian dynamics and steroid hormone concentrations

Generally, sika deer conceive a single fetus, but approximately 80% of pregnant females have two corpora lutea (CLs). The function of the accessory CL (ACL) is unknown; moreover, the process of ACL formation is unclear, and understanding this is necessary to know its role. To elucidate the process of ACL formation, the ovarian dynamics of six adult Hokkaido sika deer females were examined ultrasonographically together with peripheral estradiol-17β and progesterone concentrations. ACLs formed in three females that conceived at the first estrus of the breeding season, but not in those females that conceived at the second estrus. After copulation, postconception ovulation of the dominant follicle of the first wave is induced by an increase in estradiol-17β, which leads to formation of an ACL. A relatively low concentration of progesterone after the first estrus of the breeding season is considered to be responsible for the increase in estradiol-17β after copulation.     

Corpus luteum vascularization during the maternal recognition of pregnancy in llamas (Lama glama)

The aim of this study was to characterize corpus luteum vascularization and its association with plasma progesterone concentration in early stages of pregnancy, when maternal recognition of pregnancy is expected to occur. In all animals, both plasma progesterone concentration and corpus luteum vascularization increased from Day 6 to Day 8 post-mating and afterwards in non-pregnant llamas they started to decrease to reach basal levels around Days 12 to 14 post-mating, while in pregnant animals, both variables remained elevated until the end of the study. A lineal positive relationship between corpus luteum vascularization and plasma progesterone concentration was observed in pregnant (r² = .46, p < .0001) and non-pregnant llamas (r² = .66, p < .0001). Pregnant animals showed higher plasma progesterone concentration and corpus luteum vascularization than the non-pregnant ones from Day 12 post-mating until the end of the study (p ˂ .05 and p ˂ .01, respectively). These results suggest that maternal recognition of pregnancy should occur before Day 12 post-mating in order to expand luteal lifespan, maintaining corpus luteum vascularization and progesterone production. Also, the assessment of CL vascularization area could be a useful and non-invasive method for early pregnancy diagnosis due to its association with plasma progesterone concentration.     

牦牛不同妊娠阶段孕酮的主要来源器官研究

为明确牦牛不同妊娠阶段孕酮的来源,分别对53头不同妊娠阶段牦牛的黄体组织、肾上腺组织和胎盘组织进行体外细胞培养,同时对44头牦牛的上述组织进行匀浆处理,采用放射免疫分析法（RIA）测定培养液及组织匀浆上清液中孕酮的含量。结果显示,黄体细胞在体外培养时,妊娠前2个月内孕酮分泌量显著升高（P〈0．05）：妊娠2-5个月,培养液中孕酮含量变化不明显（P〉0．05）,但在妊娠5个月以后,其浓度又开始显著增加（P〈0．01）。肾上腺组织体外培养时,分泌孕酮的能力随不同个体差别较大,孕酮浓度在整个妊娠期变化不明显（P〉0．05）。胎盘组织体外培养时仅分泌少量孕酮,且在整个妊娠期其浓度变化不明显。黄体组织匀浆上清液中孕酮浓度在妊娠前2个月内呈上升趋势（P〈0．05）,之后其浓度开始下降,至妊娠第4个月时下降到最低水平,以后又逐渐上升（P〈0．05）,妊娠6-7个月时达到峰值,临近分娩时,又下降至较低水平。肾上腺组织匀浆中孕酮含量的变化差异较大,且无明显的变化趋势,胎盘组织匀浆中孕酮的含量也很低,甚至检测不到。结果表明,黄体是牦牛整个妊娠期孕酮的主要来源器官。     

Roles of reactive oxygen species in the corpus luteum

Cells living under aerobic conditions always face the oxygen paradox. Oxygen is necessary for cells to maintain their lives. However, reactive oxygen species such as superoxide radicals, hydroxyl radicals and hydrogen peroxide are generated from oxygen and damage cells. Oxidative stress occurs as a consequence of the excessive production of reactive oxygen species and impaired antioxidant defense systems. Antioxidant enzymes include superoxide dismutase (SOD), which is a specific enzyme to scavenge superoxide radicals; copper‐zinc SOD, located in the cytosol and Mn‐SOD, located in the mitochondria. Both types of SOD belong to the first enzymatic step to scavenge superoxide radicals. It has been reported that a number of local factors such as cytokines, growth factors and eicosanoids are involved in the regulation of the corpus luteum (CL) function in addition to gonadotropins. Since reactive oxygen species are generated and SOD is expressed in the CL, there is a possibility that reactive oxygen species and SOD work as local regulators of the CL function. The present review reports that reactive oxygen species and their scavenging systems play important roles in the regulation of the CL function.     

Short‐term intake of β‐carotene‐supplemented diets enhances ovarian function and progesterone synthesis in goats

The effect of β‐carotene supplementation upon luteal activity, measured as number (CLT) and volume (VLT) of corpus luteum, and P4 synthesis in goats, was evaluated. Goats (n = 22, 34 months) were randomly assigned to one of two experimental groups: (i) β‐carotene [Beta, n = 10; body weight (BW = 44.8 ± 1.45 kg), body condition score (BCS = 3.25 ± 0.07)], and (ii) Control (Control, n = 12; BW = 45.30 ± 1.32 kg, BCS = 3.33 ± 0.06). Upon oestrus synchronization, the Beta group received 50 mg of β‐carotene per day during 35 days pre‐ and 17 days post‐ovulation. The day 4, 8, 12 and 16 post‐ovulation, blood samples were collected for quantification of serum P4 concentrations by radioimmmunoassay, and transrectal ultrasonographic scanning was performed at day 18 for evaluating CLT and VLT. Overall, CLT and VLT mean were 3.10 and 2211.1 mm³ respectively. The Beta‐goats depicted both the largest values for CLT (p = 0.07) and serum P4 levels (p = 0.05), with no differences (p = 0.53) for VLT between treatments. Results suggest a higher efficiency within the cellular‐enzymatic groups defining the steroidogenic pathways in the β‐carotene‐supplemented goats, generating a larger P4 synthesis. The last is essential for ovulation of healthy oocytes, maintenance of uterine quiescence, nourishment and survival of the embryo around implantation; all of them of paramount significance during the maternal recognition of pregnancy process.     

Effects of amino acids supplementation in low crude protein diets on growth performance,carcass traits and serum parameters in finishing gilts

This study investigated the effects of amino acids (AA) supplementation in low crude protein (CP) diets on growth performance and carcass characteristics in finishing gilts. One hundred and eighty gilts (59.1 ± 5.1 kg) were randomly allotted to one of five diets which consisted of a high CP (15.6%) diet or four low CP (11.6%) diets for 50 days. The low CP diets were supplemented with lysine + threonine + methionine (LCM), LCM + tryptophan (LCT), LCT + valine (LCV) or LCV + isoleucine (LCI), respectively. Gilts were housed at six pigs per pen with six pens per treatment. At the end of the 50‐day experiment, 30 gilts (one pig per pen) with average body weight (BW) of 98 kg were killed to evaluate carcass traits. The pigs fed the diet supplemented with LCV obtained the highest average daily gain (ADG), which was higher than those of pigs fed the diet supplemented with LCM (P < 0.05). Dietary supplementation with tryptophan, valine and isoleucine in low CP diets increased ADG (linear and quadratic effect, P < 0.05), serum levels of valine (quadratic effect, P < 0.05) and isoleucine (linear and quadratic effect, P < 0.05) and immunoglobulin G (IgG) and IgA (linear and quadratic effect, P < 0.05) in finishing gilts. © 2016 Japanese Society of Animal Science     

Quantitative analyses of insulin-like peptide 3 and sex steroid hormones in dominant follicles and corpora lutea during the estrus cycle and in follicular cysts in beef heifers

Insulin-like peptide 3 (INSL3) and sex steroids were measured in bovine dominant follicles and corpora lutea during the estrus cycle and in follicular cysts. Paired ovaries from beef heifers (n = 47) were classified, by their morphological features, either into four stages of the estrus cycle (Day 1 = day of ovulation, Day 20 = day of estrus) as Stage I (Days 1–4; n = 8), Stage II (Days 5–10; n = 10), Stage III (Days 11–17; n = 8), and Stage IV (Days 18–20; n = 11) or follicular cystic (n = 10). Cysts (n = 15) were subdivided into estrogen-active (n = 7) and estrogen-inactive (n = 8) cysts. INSL3, testosterone, and estradiol-17β concentrations in the dominant follicular fluid of Stage IV were higher than those in Stages II and III (P < 0.05). INSL3 concentrations in the cystic fluid were similar to those in dominant follicles at Stage IV, whereas testosterone and estradiol-17β concentrations were lower in cysts (P < 0.05). INSL3 content per estrogen-inactive cyst was higher than that of Stage IV (P < 0.05). INSL3 and progesterone concentrations in luteal tissue and contents per corpus luteum were higher in Stages II and III (P < 0.05). In conclusion, INSL3 secretion in bovine dominant follicles increased with maturation. Follicular cysts may retain the production of INSL3 during their formation but tend to lose the capacity for testosterone secretion. Estrogen-inactive cysts subjected to advanced atresia may accumulate more INSL3. INSL3 production in bovine corpora lutea is enhanced during maturation.     

Presence of multiple corpora lutea affects the luteolytic response to prostaglandin F2α in lactating dairy cows

Since the 1970s, luteolytic doses used for synchronizing estrus in dairy cattle have remained unchanged. This study aimed to evaluate the dose-response effect of prostaglandin F_2α (PGF_2α), which is used for synchronizing estrus, and subsequent fertility in cows with two or more corpora lutea (CL). The study population consisted of 1,683 cows with a single CL (1CL), 501 cows with multiple CL receiving a single dose of PGF_2α (2CL1), and 252 cows with multiple CL receiving a 1.5 × PGF_2α dose (2CL1.5). Cows with a single CL (n = 1,245) showed estrus significantly (P < 0.01) earlier (3.01 ± 1.23 days; mean ± SD) than cows with multiple CL (n = 287; 3.33 ± 1.69 days). Using 1CL cows as reference, the odds ratio (OR) for the estrus response in 2CL1 cows was 0.13 (P < 0.0001), whereas the ORs for estrus response and pregnancy of 2CL1.5 cows were 1.8 (P = 0.0001) and 1.7 (P = 0.001), respectively. Based on the results for only the 2CL1 cows, the OR for the estrus response was 0.7 (P = 0.01) for cows producing ≥ 45 kg of milk at treatment, compared to the remaining cows producing < 45 kg of milk. Our results showed that the presence of multiple CL reduced the estrus response to that induced by a single PGF_2α dose and milk production was inversely associated with this response, whereas an increased PGF_2α dose improved the estrus response. Therefore, an increase in the standard PGF_2α dose is recommended.     

Effect of prolonged branched-chain amino acid supplementation on metabolic response to anaerobic exercise in standardbreds

This study investigated the effect of prolonged BCAA supplementation on metabolic response to a 1600m run on treadmill in Standardbred trotters. Four trained Standardbreds were divided into two groups and assigned in a 2×2 Latin square design. Both groups were fed and exercised similarly: one group received an oral amino acids supplement (12 g leucine, 9 g isoleucine and 9 g valine) 30 minutes prior to exercise and immediately after, the other group received a placebo. The horses received the supplement 3 days per week for 5 weeks. In the last week horses performed an anaerobic exercise test on an inclined (3.5%) high-speed treadmill. The exercise consisted of a 15 minute warm-up phase immediately followed by a 1600 m run at maximal speed (heart rate > 200 beats/min). Blood samples were collected pre-exercise, after exercise and during recovery (10 min, 30 min, and 24 h), and analyzed for lactate, ammonia, total protein, urea, uric acid, creatinine, free fatty acids (FFA), creatine kinase (CK), lactate dehydrogenase (LDH), aspartate amino transferase (AST). Heart rate was continuously recorded during exercise and recovery. No statistical differences between the groups were observed for all the considered parameters. Nevertheless, BCAA supplementation resulted in a higher plasma ammonia and urea concentrations as reported in previous studies in humans and rats. These data suggest that a BCAA supplementation are not effective in enhancing performance in healthy and well-fed horses.     

Determination of the relationship between serum anti‐Müllerian hormone level and superovulatory response in Simmental cows

The most significant focal points of the embryo transfer technology are as follows: the selection of donors, the response of the selected donor to the superovulation protocol and the obtained number of the transferable embryos. For this purpose, it is suggested that donor selection can be done by anti‐Müllerian hormone (AMH) levels, and embryo production is evaluated. AMH is secreted by the granulosa cells of primordial, pre‐antral and antral follicles below 4 mm in the ovary, independent of FSH. Therefore, the aim of this study was to investigate the relationship between serum AMH levels and the number of corpus luteum (CL), total embryos and transferable embryos that were shaped after a uniform superovulation protocol. For this reason, 48 Simmental cows, which were located at General Directory of Agricultural Enterprises (region, province, etc. instead of the general directorate), were used as donors for the embryo transfer. Blood samples were taken at random, regardless of the stage of animal's sexual cycle. AMH levels were measured by enzyme‐linked fluorescent assay (ELFA) method of the miniVIDAS^® (bioMérieux SA) using AMH Bovine Test Kit. According to the statistical analyses of the obtained data, AMH levels were positively correlated with CL and total embryos (p < .05). No significant correlations between AMH and transferable embryos were approved (p > .05). It was also determined that each 200 pg/ml increase in serum AMH level resulted in one increase in CL number. Overall, considering the positive correlation between AMH level and the obtained number of CL and total embryos after a superovulation treatment, it was concluded that measuring blood AMH level prior to any further costly implementation may be an effective method in donor selection.     

Effects of cysteamine supplementation on the intestinal expression of amino acid and peptide transporters and intestinal health in finishing pigs

This study aimed to evaluate the effects of cysteamine supplementation on the expression of jejunal amino acid and peptide transporters and intestinal health in finishing pigs. Sixty barrows were allocated into two experimental diets consisting of a basal control diet supplemented with 0 or 142 mg/kg cysteamine. After 41 days, 10 pigs per treatment were slaughtered. The results showed that cysteamine supplementation increased the apparent digestibility of crude protein (CP) (P < 0.05) and the trypsin activity in jejunal digesta (P < 0.01). Cysteamine supplementation also increased the messenger RNA abundance of SLC7A7, SLC7A9 and SLC15A1, occludin, claudin‐1 and zonula occludens protein‐1 (P < 0.001) in the jejunum mucosa. Increased glutathione content (P < 0.01) and glutathione peroxidase activity (P < 0.05) and decreased malondialdehyde content (P < 0.01) were observed in pigs receiving cysteamine. Additionally, cysteamine supplementation increased the concentrations of secretory immunoglobulin A (IgA) (P < 0.05), IgM (P < 0.001) and IgG (P < 0.001) in the jejunal mucosa. It is concluded that cysteamine supplementation could influence protein digestion and absorption via increasing trypsin activity, enhancing the digestibility of CP, and promoting the expression of jejunal amino acid and peptide transporters. Moreover, cysteamine improved intestinal integrity, antioxidant capacity and immune function in the jejunum, which were beneficial for intestinal health.     

Use of two cloprostenol administrations 11.5 days apart efficiently synchronizes oestrus in photostimulated multiparous dairy goats in the non-breeding season

This study assessed the efficiency of synchronous oestrous induction by light programme followed by two doses of cloprostenol in acyclic Saanen goats of different parity orders. Primiparous (n = 22) and multiparous (n = 33) goats were subjected to 16 hr of light and 8 hr of darkness for 60 days (D0-D60), starting 10 days after the winter solstice. All goats received 120 µg cloprostenol doses on D130 (morning) and D141.5 (afternoon) (11.5 days apart). Oestrus behaviour, ovarian follicular dynamics and serum progesterone (P4) analyses were recorded from D0 to D174 at different intervals. Animals in oestrus after D141.5 were randomly assigned into two groups: assisted natural mating (NM) or artificial insemination (AI; 10–24 hr after oestrus onset with frozen-thawed semen). From D57 to D120, 89.0% of goats presented large follicles (5–8 mm) and P4 concentrations were subluteal from D0 to D120. More multiparous compared to primiparous goats (54.5%, 18/33 vs. 18.2%, 4/22) exhibited oestrus after both injections. More primiparous compared to multiparous goats (54.5%, 12/22 vs. 12.1%, 4/33) did not exhibit oestrus after any injection. A total of 35 goats (64%) were in oestrus after the second prostaglandin injection and were subjected to NM or AI. The conception rate was similar among primiparous (70.0%, 7/10) and multiparous (68.0%, 17/25) goats but the pregnancy rate differed, being 31.8% (7/22) and 51.5% (17/33), respectively. No interaction was found between parity order and P4 concentrations in does that became pregnant or not. Thus, the association between light programme (60 days, starting at the beginning of winter) and two cloprostenol administrations 11.5 days apart (starting 70 days after the end of the light treatment) resulted in sufficient synchronous oestrous response in multiparous acyclic Saanen goats to reach satisfactory fertility levels after both NM and AI.     

Crystalline amino acids supplementation improves the performance and carcass traits in late‐finishing gilts fed low‐protein diets

This study investigated the effects of amino acids (AA) supplementation in low‐crude protein (CP) diets on the growth performance and carcass characteristics in late‐finishing gilts. Ninety gilts (93.8 ± 5.5 kg) were randomly allotted to one of the five diets which consisted of a normal‐CP (137 g/kg) or four low‐CP (105 g/kg) diets for 28 days. The low‐CP diets were supplemented with lysine + threonine + methionine (LCM), LCM + tryptophan (LCT), LCT + valine (LCV) or LCV + isoleucine (LCI), respectively. Non‐significant difference in average daily gain (ADG) was obtained in gilts receiving the control and LCV diet, which was higher than that of gilts fed the LCM diet (p < .05). The additions of crystalline AA in the low‐CP diet resulted in the improvements in ADG (linear and quadratic effect, p < .05) and fat‐free lean gain (quadratic effect, p < .05) and influenced the valine concentration (linear and quadratic effect, p < .05) and proportion of saturated fatty acid (linear effect, p < .05) in longissimus muscle. The results indicated that the valine supplementation could further improve the performance in 94 to 118 kg gilts fed the 105 g/kg CP diet.     

Uptake of manganese from manganese–lysine complex in the primary rat intestinal epithelial cells

This study was conducted to compare the differences of the uptake of Mn from Mn–lysine complex (MnLys) and MnSO₄ and to determine the potential mechanisms of the uptake of Mn from MnLys. We first established the primary rat intestinal epithelial cell culture model and used it to determine the uptake of Mn from different Mn sources. The MnLys increased (p < 0.001) Mn uptake when compared to MnSO₄. The uptake of Mn decreased (p < 0.05) with added Fe concentration increasing in the medium regardless of Mn source. The MnLys decreased (p < 0.01) Mn²⁺ efflux transporter ferroportin 1 (FPN1) mRNA level, but did not influence (p > 0.06) Mn²⁺ influx transporter DMT1 mRNA expression when compared to MnSO₄. The results above indicated that the increase of Mn accumulation for MnLys at least partly was due to the decrease of Mn efflux by reduced FPN1 expression. The N‐ethylmaleimide, as an l ‐lysine transport system y⁺ inhibitor, decreased (p < 0.001) the uptake of Mn from MnLys, but did not affect (p > 0.10) the uptake of Mn from MnSO₄. The cycloheximide, as an l ‐lysine transport system b^0,+ activator, increased (p < 0.001) the uptake of Mn from MnLys, whereas also did not influence the uptake of Mn from MnSO₄. The MnLys increased (p < 0.01) the system y⁺ member cationic amino acid transporter (CAT) 1, and system b^0,+ components rBAT and b^0,+AT mRNA expression when compared to MnSO₄. These results suggested that the uptake of Mn from MnLys complex might be transported by CAT1 and system b^0,+, which was different from ionized Mn²⁺ uptake pathway. In conclusion, the uptake of MnLys complex not only might be absorbed as Mn²⁺, but also appeared to be transported through CAT1 and system b^0,+ in the primary rat intestinal epithelial cells.