Melatonin Implants Research Articles

Melatonin implants in late pregnancy increase yield and enhance milk quality in dairy goats

Melatonin implants in late pregnancy increase yield and enhance milk quality in dairy goats

Effect of Melatonin on the Production Performance, Blood Biochemical Parameters, Nutrient Digestibility, and Gastrointestinal Microbiome of Liaoning Cashmere Goats

Melatonin’s capacity to improve cashmere production and quality in goats is well established, but its underlying mechanisms, particularly those concerning the gastrointestinal microbiome, remain inadequately understood. This study aims to elucidate the effects of melatonin implantation on the production performance, blood biochemical parameters, nutrient digestibility, and gastrointestinal microbiome of Liaoning cashmere goats. Thirty newborn Liaoning cashmere goat lambs were selected and randomly assigned to control and melatonin groups using a paired test design. The melatonin group received three melatonin implantations at 15, 75, and 135 days of age, respectively, with a dosage of 2 mg/kg body weight, while the control group received no treatment. Digestive metabolism tests were conducted at 150 and 300 days of age; prior to these tests, blood, rumen fluid, and rectal feces were collected. Apparent nutrient digestibility and blood biochemical indexes were determined, and rumen fluid and rectal feces were analyzed using microbial 16S rRNA sequencing. The results indicated that melatonin significantly reduced daily weight gain and body weight at 60 days (p < 0.05) while significantly increasing daily weight gain at 300 days (p < 0.05). Additionally, it significantly increased cashmere length and reduced its fineness (p < 0.05). Melatonin significantly enhanced nitrogen deposition (p < 0.05), elevated plasma levels of T-AOC, CAT, GSH-PX, and BUN (p < 0.05), and reduced plasma levels of MDA, GOT, GPT, and AKP (p < 0.05). Moreover, melatonin significantly elevated the microbial Ace and Chao1 indices in rectal feces (p < 0.05), increasing genera beneficial for feed digestion and absorption, including Prevotella, Lachnospiraceae, Ruminococcus, and Synergistaceae (p < 0.05); the abundance of these beneficial genera were positively correlated with improved cashmere production performance, antioxidant activity, and liver and kidney function. In conclusion, melatonin enhances cashmere production by modulating gastrointestinal microbiota, antioxidant activity, liver and kidney function, and nitrogen metabolism in cashmere goats. This study provides a theoretical foundation for melatonin’s role in microbiota modulation, which is essential for promoting high-quality and sustainable development in the cashmere goat industry.

Exogenous melatonin ameliorates embryo-maternal cross-talk in early pregnancy in sheep.

Melatonin plays a crucial role in enhancing reproductive performance in small ruminants. This paper reveals the effects of exogenous melatonin on the placental and endometrial rearrangement in early pregnancy in sheep. Early pregnancy losses cause 25% of pregnancy failures in small ruminants because of asynchrony between conceptus and uterine signals. In this context, melatonin plays a crucial role in sheep reproductive dynamics, but little is known about its effects during the peri-implantation period. We hypothesized that melatonin supports embryo implantation by modulating the uterine microenvironment. This study aimed to assess the effects of exogenous melatonin on the endometrial and early placental rearrangement. Ten multiparous ewes either did (MEL, n = 5) or did not (CTR, n = 5) receive a subcutaneous melatonin implant (18 mg) 50 days before a synchronized mating. On day 21 of pregnancy, the sheep were euthanized. MEL ewes exhibited a higher prolificity rate (2.8 vs 2.0 embryos/ewe) and plasma progesterone levels (3.84 vs 2.96 ng/mL, P < 0.05) than did CTR ewes. Groups did not differ significantly in embryo crown-rump length. MEL placentas had significantly (P < 0.001) more binucleated trophoblast cells in the chorion region, and ovine placental lactogen expression was significantly (P < 0.05) more strongly upregulated than in CTR. Exogenous melatonin increased significantly (P < 0.05) gene expression of angiogenic factors (VEGFA, VEGFR1, IGF1R), IFNAR2, and PR in the caruncular endometrium. Expression of the MT2 receptor in the endometrium and placenta was significantly (P < 0.05) higher in the MEL group. These results indicate that melatonin implants acted differentially on uterine and placental rearrangement. Melatonin increases differentiation in the placenta and induces changes that could promote vessel maturation in the endometrium, suggesting that it enhances the uterine microenvironment in the early stage of pregnancy in sheep.

Influence of Exogenous Melatonin Treatment on the Ram Fertility of the North-east Bulgarian Fine-wool Sheep Breed

The potential of the epiphyseal hormone melatonin to effect on seasonally breeding species has been extensively studied, but the data remain inconclusive. Levels of reproductive parameters modulation are important to monitoring, given the breed affiliation, as example analyzed breed, which has a pronounced seasonal type of reproduction. The objective of this study was to determine whether application of exogenous melatonin has an effect on ram fertility of the North-east Bulgarian fine-wool sheep breed, as estimated by the reproductive performances of ewes, in the non-breeding season. In addition, the study quantified the effects of exogenous melatonin on ejaculate volume and concentration of sperm in rams with melatonin implants (n = 5) and per os treated rams (n = 5). The application of exogenous melatonin improves the fertility of rams of the studied breed. As a result of the current study, in the 2nd experimental group there was a positive trend on ejaculate volume and concentration of sperm throughout the experiment compared to control group. Although rams exhibited an improvement in sperm parameters, a significantly increased birth rate was found in sheep mating with male receiving melatonin both through implants (P &lt; 0.05) and per os (P &lt; 0.05). It was found to increase the total percentage of birth lambs in 1st (28%) and 2nd (29%) experimental groups compared to control. The results are guiding for North-east Bulgarian fine-wool sheep farmers and breeders, in terms of opportunities to improve the breeding process and obtain more lambs.

Effects of Melatonin Implants on Hormone Profile and Mating Behaviour in Rams

Effects of Melatonin Implants on Hormone Profile and Mating Behaviour in Rams

Effects of melatonin implants on reproductive performance in sheep: a systematic review and meta-analysis

Context Sheep are seasonal breeding animals. Different reproduction systems exist to enhance productivity in non-breeding season. One of the methods used in enhancing reproductive performance in sheep breeding is melatonin administration. Aim This study aimed to evaluate the impact of melatonin application on reproductive performance in sheep by meta-analysis according to different factors. Methods To find eligible studies, PubMed and Web of Science databases were searched. Twenty studies published between 1991 and 2021 were included in the meta-analysis. The effect sizes of pregnancy rate, lambing rate and litter size were calculated according to breeds, production characteristics (dairy-meat breeds) and season (breeding–non-breeding). The study estimated the risk ratio for pregnancy and lambing rates, and standardized mean difference for litter size as effect size. Key results The melatonin hormone increases the pregnancy rate by 1.07 times and the lambing rate by 1.36 times. The effect size (risk ratio) of the Rasa Aragonesa breed (1.15) for pregnancy rate and the Merino breed (1.65) for lambing rate was higher than the Sarda breed. Conclusions The positive effect of melatonin was found to be higher in the non-breeding season than in the breeding season for the three reproductive performance traits examined. Implications This study is a comprehensive research study examining the effect of melatonin application in sheep according to different factors.

FRESH AND CRYOPRESERVED SEMEN CHARACTERISTICS OF BUFFALO BULLS AS INFLUENCED BY MELATONIN IMPLANTATION

This study explored the effect of melatonin implantation on the fresh and cryopreserved semen quality of Iraqi buffalo bulls (Bubalus bubalis). Nine adult bulls were used and divided equally into three groups. The first group was left without treatment and regarded as control (T1), whereas the second (T2) and third (T3) groups were subcutaneously implanted with 72 and 90 mg of melatonin respectively on the left ear base and repeated one month post the first implantation. Semen was collected for 12 weeks and evaluated weekly for fresh, cooling, and post-cryopreserved (PC) protocols. The T3 group exhibited a higher (P≤0.05) sperm cell individual motility percentage, whereas, the T1 and T2 groups recorded better (P≤0.05) sperm acrosome integrity percentage for fresh semen. A lesser (P≤0.05) total sperm abnormality (TSA) percentage in the T2 and T3 groups and a greater (P≤0.05) sperm acrosome integrity (SAI) percentage in the T3 group were noticed during the cooling preservation. Moreover, the T3 group exhibited a lesser (P≤0.05) TSA percentage whereas, the T2 and T3 groups revealed a leaser (P≤0.05) SAI percentage during the PC period. Concomitantly, lower (P≤0.05) PC malondialdehyde concentration in seminal plasma was observed in the T2 and T3 groups than control group. In conclusion, the melatonin implantation (72 and 90 mg) ameliorated some fresh and PC semen attributes of the Iraqi buffalo bulls.

Effect of exogenous melatonin implant on post-thaw semen quality of buffalo bulls.

Melatonin is an intracellular antioxidant of sperm membrane that protects the cells from lipid peroxidation. Yet, its role as an antioxidant on semen quality of buffalo bulls is still obscure. The present study was undertaken to assess the effect of exogenous melatonin implant (18 mg/50 kg bodyweight) on post-thaw sperm characteristics, oxidative stress, endocrinological profiles and fertility of buffalo bulls. Six apparently healthy breeding Murrah buffalo bulls were randomly selected at bull farm, Guru Angad Dev Veterinary and Animal Sciences University for the present study and divided into two groups viz. control (n = 3) and melatonin implanted group (n = 3). A total of 120 ejaculates were collected from bulls of both groups (n = 60 each) throughout the study period. Most beneficial effects of melatonin implants were observed during post-implantation period. The percentages of post-thaw sperm total and progressive motility, viability and mitochondrial membrane potential were higher (p < .05) in melatonin implanted buffalo bulls compared to controls during post-implantation period. Following melatonin implantation, MDA production in post-thaw semen was lower (p < .05) in melatonin implanted group than in control group. Plasma melatonin and testosterone concentrations were higher (p < .05) in buffalo bulls implanted with melatonin as compared to their control counterparts. No differences (p > .05) in plasma LH concentrations were observed in both groups. First service pregnancy rate was 43.3% using semen of melatonin implanted bulls and 30.0% with semen of controls (p > .05). Thus, melatonin was able to protect sperm membrane against oxidative damage and improve post-thaw semen quality, thereby resulting in higher fertilizing potential of spermatozoa.

Assessment of oxidative stress parameters in summer anestrous buffaloes exhibiting differential fertility following melatonin implants treatment

For evaluating the impact of melatonin implants treatment during non-breeding season to ameliorate oxidative stress, 132 anestrous buffaloes were subcutaneously inserted with 2x4 mm absorbable slow-release melatonin implants (18 mg/50 kg b wt) at the base of left ear and 60 buffaloes were used as control. Ovarian ultrasonography and jugular vein blood sampling were carried out at 7-day interval till day 35 post-treatment or till ovulation, whichever was earlier. Control and implanted buffaloes were subjected to artificial insemination (AI) at overt or induced estrus followed by pregnancy diagnosis at day 90 post-AI. Erythrocytic lipid peroxidation (LPO) values were reduced (P&lt;0.05) in implanted buffaloes from day 21 post-treatment onwards when compared to their pre-treatment and Control group values. However, the concentrations of erythrocytic glutathione peroxidase (GPx), glutathione reductase and superoxide dismutase (SOD) were invariably higher (P&lt;0.05) following treatment as compared to their pre-treatment and Control group values. The buffaloes ovulating in Control or Treatment group revealed higher (P&lt;0.05) erythrocytic GPx in the Latter group. Also, between pregnant counterparts of Control and Treatment group, the Latter group buffaloes exhibited low (P&lt;0.05) erythrocytic LPO, and high (P&lt;0.05) erythrocytic GPx, SOD and catalase. It can be concluded that melatonin implants treatment was successful for mitigating the oxidative stress in summer anestrous buffaloes, and the status of oxidative stress parameters following treatment was better in buffaloes that ovulated or conceived subsequently.

Impact of melatonin administration on sperm quality, steroid hormone levels, and testicular blood flow parameters in small ruminants: A meta-analysis.

The impact of exogenous melatonin on the sperm quality of small ruminants is controversial. Therefore, this study aimed to synthesize previous findings on the influence of melatonin injection on sperm quality, steroid hormones, and testicular blood flow in small ruminants. Thirty studies were analyzed by computing the raw mean difference (RMD) as the effect size between the control and melatonin treatment groups, using the inverse of the variance for the random-effect model of the method of moments by DerSimonian and Laird. We assessed heterogeneity among studies using Q test. I2 statistic was used to classify the observed heterogeneity. We used Egger's regression method to indicate publication bias. Melatonin injection (p < 0.05) affected sperm concentration (RMD = 0.42 × 109/mL), morphology (RMD = 2.82%), viability (RMD = 2.83%), acrosome integrity (RMD = 4.26%), and DNA integrity (RMD = 1.09%). Total motility (RMD = 5.62%), progressive motility (RMD = 7.90%), acrosome integrity (RMD = 8.68%), and DNA integrity (RMD = 2.01%) of post-thawed semen in the melatonin-treated group were also increased (p < 0.05). Similarly, treatment with melatonin (p < 0.05) enhanced total motility (RMD = 5.78%), progressive motility (RMD = 5.28%), curvilinear velocity (RMD = 4.09 μm/s), straight-line velocity (RMD = 5.61 μm/s), and average path velocity (RMD = 4.94 μm/s). Testosterone (RMD = 1.02 ng/mL) and estradiol 17-ß levels (RMD = 0.84 pg/mL) were elevated (p < 0.05) in the melatonin-injected group. Melatonin implantation ameliorated testicular blood flow, as indicated by a significant reduction (p < 0.05) in the resistive index (RMD = 0.11) and pulsatility index (RMD = -0.15). Melatonin administration can increase the reproductive performance of small male ruminants.

Effects of melatonin implants in late gestation and at lambing on colostrum and milk quality of ewes, birth temperature and growth performance of their lambs

The objective of this study was to measure the effects of melatonin implants in meat ewes at late pregnancy, at lambing, or both, on colostrum and milk composition, growth of their lambs, and lamb surface and rectal temperatures under intensive conditions. Pregnant Rasa Aragonesa ewes, that were previously synchronized (mean parity number ( ± SD): 2.50 ± 0.82, mean live weight: 55 ± 4 kg; mean body condition: 3.00 ± 0.25) received a subcutaneous melatonin implant thirty days before lambing (M-0, n = 14), at lambing (0-M, n = 14), at both periods (M-M, n = 10), or did not receive an implant (0–0, n = 12). Mean ( ± SD) prolificacy (number of lambs born/lambing) was 1.43 ± 0.14; 1.57 ± 0.13; 1.40 ± 0.16, and 1.42 ± 0.14 for the M-0, 0-M, M-M and 0–0 groups, resp. The distribution of lambs born according to their sex was: M-0, 7 males, 12 females; 0-M, 10 males, 11 females; M-M, 6 males, 7 females, and 0–0, 8 males, 6 females. Fat (F), protein (P), and lactose (L) content were measured in colostrum (collected at lambing) and milk (collected every two weeks), and ºBrix and IgG were quantified in colostrum. Lamb weight (LW) was recorded at birth and every two weeks until weaning (day 42 of age). At birth, lamb rectal temperature (RT) and thermography images were taken (Eye=ET; shoulder=ST; mid loin=MT; hips=HT). P and L concentrations in colostrum were significantly (P < 0.05) higher in the M-0 (P: 9.01 ± 0.45, L: 8.53 ± 0.42%) than they were in the M-M group (P: 7.38 ± 0.34, L: 6.99 ± 0.32), with no significant differences among groups for F content. No significant differences were found for birth weight among groups, as well as considering litter size. However, at weaning, male lambs reared by 0-M (12.31 ± 0.57 kg) ewes had significantly (P < 0.05) higher LW than did male lambs reared by M-0 (9.43 ± 1.01) or 0–0 (9.65 ± 0.99 kg) ewes. Lambs from M-0 and M-M ewes had the highest MT and HT, and the effects were most pronounced in male lambs. In conclusion, melatonin implants during pregnancy had positive effects on ewes by improving colostrum quality, and increased the MT and HT in lambs. Implants at lambing enhanced the productive performance of ewes and male lambs, but implants at both moments did not provide beneficial effects.

Proteomics Analysis of Pregnancy in Ewes under Heat Stress Conditions and Melatonin Administration

Melatonin is an indoleamine with broad spectrum properties that acts as a regulator of antioxidant and immune response in organisms. In our previous studies, melatonin improved redox status and inflammatory response in pregnant ewes under heat stress conditions. In the present study, using proteomics, the proteins regulated by melatonin during different stages of pregnancy and lambing were assessed. Twenty-two ewes equally divided into two groups, the melatonin (M) (n = 11) and control (C) group (n = 11), participated in the study and were exposed to heat stress during the first months of pregnancy. In the M group, melatonin implants were administered throughout pregnancy, every 40 days, until parturition (a total of four implants per ewe). Blood samples were collected at the beginning of the study simultaneously with the administration of the first melatonin implant (blood samples M1, C1), mating (M2, C2), second implant (M3, C3), fourth implant (M4, C4) and parturition (M5, C5), and MALDI-TOF analysis was performed. The results revealed the existence of 42 extra proteins in samples M2, M3 and M4 and 53 in M5 (sample at parturition) that are linked to melatonin. The biological processes of these proteins refer to boosted immune response, the alleviation of oxidative and endoplasmic reticulum stress, energy metabolism, the protection of the maternal organism and embryo development. This proteomics analysis indicates that melatonin regulates protective mechanisms and controls cell proliferation under exogenous or endogenous stressful stimuli during pregnancy and parturition.

The Effect of Subcutaneously Administered Crystal's Oily Solution on Estrus and Conception Rates in Ewes

The study aims to evaluate the effects of subcutaneously (SC) injected oily solution of melatonin crystal at different doses in 2-3 years, healthy, multiparous sheep during the anoestrus period on serum melatonin and prolactin levels, estrus occurrence, mating, conception, and pregnancy rates. The study group consists of 350 ewes. The ewes were divided into 5 groups: MEL10 (n=70, 10mg melatonin), MEL20 (n=70, 20mg melatonin), MEL40 (n=70, 40mg melatonin), placebo (n=70), and control (n=70) groups. The melatonin groups received SC injections of the oily melatonin solution 11 days before ram introduction. The placebo group received only the oily solution. The control group did not receive any treatment. Blood samples were collected from all groups before the melatonin injection and on the 11th day after the injection. The data showed that the melatonin level in the blood samples collected before and after the injection increased in the MEL10 (P:0.045) and MEL20 (P:0.0359) groups. Additionally, the prolactin level decreased in the second blood sample collected from all groups (P&gt;0.05). Regarding reproductive parameters, the estrus rate in the MEL10, MEL20, MEL40, placebo, and control groups was 75.71%, 58.57%, 54.28%, 51.42%, and 52.85%, respectively. The mating rate was 61.42%, 57.14%, 52.85%, 48.57%, and 50% in the same groups, and the pregnancy rate was 60%, 52.85%, 42.85%, 41.42%, and 38.57%, respectively. The conception rate was determined as 97%, 92%, 81%, 85%, and 77% in the MEL10, MEL20, MEL40, placebo, and control groups, respectively. In conclusion, subcutaneous injection of melatonin at appropriate doses to sheep can indirectly simulate the breeding season, and stimulate heat. Additionally, it can increase pregnancy and conception rates. This method can considered a potential alternative to melatonin implants or different synchronization methods in the future.

Effect of melatonin implantation on reproductive performance in post-partum murrah buffaloes (Bubalus bubalis) during Summer season

Effect of melatonin implantation on reproductive performance in post-partum murrah buffaloes (Bubalus bubalis) during Summer season

Effect of Melatonin Implantation on Sexual Behavior and some of Semen Quality of Iraqi Buffalo Bulls

This study investigated the effect of melatonin implantation on sexual behavior and some aspects of the semen quality of buffalo bulls. Nine buffalo bulls had divided into three groups (3/group). The first group was the control group (C1). The buffalo bulls were implanted with melatonin hormone in the second (72 mg; C2) and third (90 mg; T3) groups under the skin of the left ear base and repeated one month after the first implantation. Semen was collected for 14 weeks and evaluated weekly. The first amount of time was lower in the C3 group than in the C2 and C1 groups. Semen volume at 2nd ejaculation was higher (P<0.05) in the C3 group than in other groups. Mass activity and motility increased in the C3 group compared to the C2 and C1 groups at different ejaculation times. The melatonin implantation (90 mg) can improve the semen quality of Iraqi bulls which in turn enhancing the reproductive performance, conception rate of female buffalo and increasing the artificial insemination productivity and owner’s income.

Evaluation of the effect of melatonin implantation in rams and eCG dose in ewes synchronized by a CIDR-eCG protocol on reproductive performance of Lacaune sheep breed during non-breeding season

Sustainable production of milk is favorable in dairy sheep industry, which necessitates year-round reproduction of rams and ewes even during non-breeding season. Hence, protocols facilitating reproduction of rams and ewes during non-breeding season are of importance for this purpose. Therefore, the present study was conducted to investigate the effect of melatonin implantation in rams and administration of 400 IU eCG (E400) versus 300 IU eCG (E300) in ewes on reproductive performance of Lacaune sheep breed during non-breeding season. Rams were allocated to two groups including untreated (control, CON; n = 36) and melatonin-treated (MEL; n = 37). A subset of rams from CON (n = 7) and MEL (n = 7) groups were used for assessment of scrotal circumference, kinematic and functional characteristics of sperm, total antioxidant capacity (TAC) of semen and circulating testosterone on Days 0 (the beginning of study) and 60 (60 days after melatonin implantation). Further, the study had a 2 × 2 factorial design with four experimental groups including 1) ewes treated with E300 and introduced to CON rams (E300CON; n = 17 rams and 172 ewes), 2) ewes treated with E300 and introduced to MEL rams (E300MEL; n = 18 rams and 177 ewes), 3) ewes treated with E400 and introduced to CON rams (E400CON; n = 19 rams and 192 ewes), and ewes treated with E400 and introduced to MEL rams (E400MEL; n = 19 rams and 190 ewes). Melatonin implantation improved scrotal circumference, concentration, progressive motility, velocity, mitochondrial membrane potential and viability of sperm, TAC of semen, concentration of testosterone and fertility of rams (P < 0.05). Besides, E400 compared with E300 enhanced synchronization of estrus and fertility in ewes (P < 0.05). In conclusion, melatonin implantation promoted reproductive performance in Lacaune rams, and increase in dose of eCG improved reproductive performance in Lacaune ewes.

EFFECT OF MELATONIN AND VITAMIN E AS ANTIOXIDANTS ON BODY WEIGHT, CARCASS TRAITS OF AWASSI LAMBS FED A HIGH-ENERGY AND NORMAL DIET

This experiment was carried out to evaluate the effects of vitamin E (Alpha tocopherol acetate) supplementation and melatonin implants on growth performance, and meat quality traits of Awassi male lambs fed by a high and normal energy concentrated diet in Iraq. Lambs were divided equally to two main groups to be fed either high or normal energy diet ,and each of them divided in to five treatment, the first as a control (T1,T6),two level of melatonin (18, 36mg/lamb) were applied to (T2,T3,T7,T8) and two level of vitamin E (200,400mg/lamb/day) to (T4,T5,T9,T10).All animals were slaughtered at the end of the fattening period. Lambs received 400 g/day vitamin E with high energy diet surpassed significantly other treatment in final weight gain, vitamin E 400 mg/lamb/day and melatonin 18-36 mg/lamb at day 14 of storage increased retail color stability. enhanced meat color parameters. Melatonin implantation 18 mg/lamb, 36 mg /lamb significantly at day 7 of storage reduced MDA value, but at day 14 of storage vitamin E 200 and 400 mg/day/lamb reduced significantly MDA value of the Muscle Longissimus dorsi (LD) during storage.

Assessment of plasma melatonin profile in summer anestrous buffaloes exhibiting differential fertility following melatonin implants treatment

Plasma melatonin vis-a-vis anestrus or estrus status of buffaloes during summer or winter season (n=50 in each group) suggested its impact on reproductive axis as plasma melatonin activity tended to be higher (P&gt;0.05) in buffaloes exhibiting estrus compared to their anestrous counterparts irrespective of season. The differential reproductive status of these buffaloes was confirmed by history as well as differences (P&lt;0.05) in diameter of largest follicle and luteal profile. Further, for evaluating the impact of melatonin treatment during summer season on reproductive axis, 132 anestrous buffaloes were subcutaneously inserted 2x4 mm absorbable slow-release melatonin implants (18 mg/50 kg b wt) at the base of left ear and 60 buffaloes were used as control. In these buffaloes, ovarian ultrasonography and jugular vein blood sampling was carried out at 7-day interval till day 35 post-treatment or till ovulation, whichever was earlier. Control and implanted buffaloes were subjected to artificial insemination (AI) at overt or induced estrus followed by pregnancy diagnosis at day 90 post-AI. In treatment group, an increase (P&lt;0.05) in plasma melatonin was recorded in all the buffaloes, exhibiting differential fertility status, during post-treatment study period compared to their pre-treatment and control group values. However, within treatment group, there was no difference (P&gt;0.05) in plasma melatonin between ovulatory or non-ovulatory as well as between pregnant or non-pregnant counterparts. Moreover, plasma melatonin within control buffaloes remained similar (P&gt;0.05) throughout the study period irrespective of differential exhibition of fertility. It can be concluded that factors other than circulating melatonin are also involved in the display of differential fertility in terms of initiation of ovarian cyclicity/ovulation or ability to conceive in summer anestrous buffaloes.

Effects of melatonin implants on locomotor activity, body temperature, and growth of lambs fed a concentrate-based diet

Melatonin is involved in the regulation of circadian rhythms and is implicated in seasonal reproduction in sheep. In several physiological mechanisms, it acts as an antioxidant and an anti-inflammatory molecule, regulating energy metabolism. This work investigated the effects of melatonin implants at 30 days of age on locomotor activity (LA), body temperature, and growth of fattening female and male lambs. Sixty lambs were divided into two groups: one of which received melatonin (MEL, 15 males, 16 females) and a control group (CTR, 16 males, 14 females). In the melatonin group, two 18 mg melatonin implants were placed at 30 days of age. Lambs were fattened for 6 weeks from weaning (45 days of age) to slaughter (85 days). The feed conversion rate (FCR) was calculated based on live weight and the amount of concentrate consumed. LA was measured weekly by actigraphy, and circadian rhythmicity was calculated. Rectal (Trec) and surface temperatures (Tsur) were recorded in the last week of fattening, and subcutaneous fat thickness (FT) over the longissimus dorsi muscle was measured by ultrasound scanning. Treatment did not affect FCR, although MEL female lambs consumed significantly (P < 0.001) less concentrate than CTR lambs. Treatment and sex had a significant (P < 0.05) interaction effect on FT; specifically, FT was significantly (P < 0.05) higher in female MEL lambs (3.22 ± 0.21 mm) than in female CTR lambs (2.57 ± 0.24 mm), but FT in males did not differ between MEL (2.77 ± 0.21) and CTR (2.94 ± 0.24 mm) lambs. Overall activity was significantly (P < 0.001) lower in the MEL lambs (72.22 ± 0.10 counts/min) than in the CTR lambs (78.89 ± 0.12 counts/min). MEL lambs had a significantly (P < 0.01) lower Trec (CTR: 39.00 ± 0.07; MEL: 38.68 ± 0.10) and Tsur for all body regions evaluated than the CTR lambs. In conclusion, treatment with exogenous melatonin at 30 days of age increased food efficiency in fattening female lambs, probably, because of the lower metabolism in treated lambs, which was reflected by the lower body temperature and LA exhibited by these animals. In addition, the study has demonstrated the effect of exogenous melatonin in the growth performances of post-weaning lambs, and that its effects depend on animal sex, which suggests that treatments that target females might be most appropriate in the fattening period.

Effect of melatonin implantation prior to ovsynch plus cidr protocol on subsequent ovarian activity and pregnancy rate in summer anestrous Murrah buffaloes

For assessing the impact of melatonin pre-treatment in summer anestrous Murrah buffaloes on subsequent reproductive activity of a fixed time artificial insemination (FTAI) protocol, 83 anestrous Murrah buffaloes were subcutaneously inserted 2x4 mm size absorbable melatonin (MT) implants (18 mg/50 kg b wt) at the base of left ear and 38 Murrah buffaloes were used as non-implanted controls. On day 35 post-MT, the treatment and control group Murrah buffaloes were subjected to FTAI protocol (Ovsynch plus CIDR). Ovarian ultrasonography and jugular vein blood sampling was carried out on day 7 and 10 of protocol and on day 7-post AI. Overall pregnancy rate on day 90 post-AI in MT group was higher compared to control group (55.4 vs 31.6%, P&lt;0.05), along with the higher (P&gt;0.05) plasma progesterone on day 7 of FTAI protocol in Murrah buffaloes of the former group which conceived subsequently compared to their non-pregnant counterparts. Moreover, MT group had higher (P&gt;0.05) increase in dominant follicle diameter between day 7 and 10 of protocol compared to control group. On day 7 post-AI, the luteal profile in pregnant murrah buffaloes of MT group was better (P&lt;0.05) compared to their counterparts in control group (CL: 14.80±0.70 vs 10.82±0.46 mm, P4: 1.54±0.07 vs 1.04±0.08 ng/ml). In conclusion, melatonin pre-treatment in summer anestrous Murrah buffaloes could be associated with better luteal activity and higher pregnancy rate in the Ovsynch+CIDR protocol.