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T. E. Trigg - One of the best experts on this subject based on the ideXlab platform.
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Preliminary study of ovarian activity in Fillies treated with a GnRH vaccine.
Australian veterinary journal, 1997Co-Authors: U. Tshewang, K. F. Dowsett, L. M. Knott, T. E. TriggAbstract:OBJECTIVE: To investigate the effects of two doses (200 and 400 mg) of a water-soluble gonadotrophin-releasing hormone vaccine on the ovarian activity of 2-year-old Fillies. DESIGN: A controlled vaccination dose rate experiment. ANIMALS: Six 2-year-old Australian Stock Horse Fillies were randomly allocated to three treatment groups; unvaccinated controls, those receiving 200 mg of the vaccine and those receiving 400 mg of the vaccine. RESULTS: Ovarian activity of the treated Fillies was suppressed at the peak of breeding season while that of untreated controls continued normally. The control Fillies displayed oestrous activity and behaviour. Suppression of ovarian activity occurred for 25 and 30 weeks in the 200 and 400 mg groups, respectively. These differences were not significant. Ovarian activity ceased 2 to 3 weeks after primary vaccination. Antibody titres were low (330) until after the booster immunisation when they rapidly peaked at 22,000 and 28,000 in the 200 mg and 400 mg groups, respectively. Plasma progesterone concentrations of the treated Fillies remained below 3.18 nmol/L while GnRH was suppressed. The vaccine had no significant effect on plasma androstenedione concentrations. Recovery from the effect of the vaccine was associated with development of ovarian follicles, normal oestrous behaviour and ovulation. Three of the four treated Fillies and one of the controls conceived during the next breeding season and foaled normally. All the treated Fillies conceived and produced normal foals in the following two breeding seasons. CONCLUSION: Both dose rates suppressed ovarian function and prevented oestrous behaviour. These effects were reversible and the subsequent fertility of the vaccinated Fillies was normal.
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Immunocastration of colts and immunospeying of Fillies
Immunology and Cell Biology, 1993Co-Authors: K. F. Dowsett, U. Tshewang, L. M. Knott, A. E. Jackson, T. E. TriggAbstract:A series of experiments using an ovalbumin conjugated gonadotrophin releasing hormone was used to stimulate antibody production, suppress testosterone secretion and depress testicular function in yearling and 2 year old colts and Fillies. In the preliminary experiment, an injectable oil-based formulation was administered to yearling colts. Testicular development and testosterone secretion were retarded for a period of approximately 28-32 weeks while antibody titres were greater than 1:1000. An implant and water-soluble vaccine (200 and 400 mg) is presently being tested in 2 year old colts. Testicular dimensions and testosterone concentrations decreased following vaccination. Preliminary results indicate that the effects of the implant are reversible and last for approximately 30 weeks. The water-soluble vaccine produced effective antibodies for 10-19 weeks. Plasma testosterone of all colts was reduced to gelding levels (0.2 ng/mL) while antibody titres were greater than 1:1000. Semen evaluation, morphometric analysis and daily sperm production data indicate that the testes recovered normal function. These experiments are continuing and more definitive data on the vaccine and its reversibility will be available at their conclusion. Ovarian activity of the treated Fillies (200 and 400 mg) ceased soon after vaccination. Their progesterone concentrations have remained below 1 ng/mL for 20 weeks. The untreated control Fillies have continued to cycle normally as determined by ovarian ultrasonography and progesterone concentrations.
K. F. Dowsett - One of the best experts on this subject based on the ideXlab platform.
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Preliminary study of ovarian activity in Fillies treated with a GnRH vaccine.
Australian veterinary journal, 1997Co-Authors: U. Tshewang, K. F. Dowsett, L. M. Knott, T. E. TriggAbstract:OBJECTIVE: To investigate the effects of two doses (200 and 400 mg) of a water-soluble gonadotrophin-releasing hormone vaccine on the ovarian activity of 2-year-old Fillies. DESIGN: A controlled vaccination dose rate experiment. ANIMALS: Six 2-year-old Australian Stock Horse Fillies were randomly allocated to three treatment groups; unvaccinated controls, those receiving 200 mg of the vaccine and those receiving 400 mg of the vaccine. RESULTS: Ovarian activity of the treated Fillies was suppressed at the peak of breeding season while that of untreated controls continued normally. The control Fillies displayed oestrous activity and behaviour. Suppression of ovarian activity occurred for 25 and 30 weeks in the 200 and 400 mg groups, respectively. These differences were not significant. Ovarian activity ceased 2 to 3 weeks after primary vaccination. Antibody titres were low (330) until after the booster immunisation when they rapidly peaked at 22,000 and 28,000 in the 200 mg and 400 mg groups, respectively. Plasma progesterone concentrations of the treated Fillies remained below 3.18 nmol/L while GnRH was suppressed. The vaccine had no significant effect on plasma androstenedione concentrations. Recovery from the effect of the vaccine was associated with development of ovarian follicles, normal oestrous behaviour and ovulation. Three of the four treated Fillies and one of the controls conceived during the next breeding season and foaled normally. All the treated Fillies conceived and produced normal foals in the following two breeding seasons. CONCLUSION: Both dose rates suppressed ovarian function and prevented oestrous behaviour. These effects were reversible and the subsequent fertility of the vaccinated Fillies was normal.
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Immunocastration of colts and immunospeying of Fillies
Immunology and Cell Biology, 1993Co-Authors: K. F. Dowsett, U. Tshewang, L. M. Knott, A. E. Jackson, T. E. TriggAbstract:A series of experiments using an ovalbumin conjugated gonadotrophin releasing hormone was used to stimulate antibody production, suppress testosterone secretion and depress testicular function in yearling and 2 year old colts and Fillies. In the preliminary experiment, an injectable oil-based formulation was administered to yearling colts. Testicular development and testosterone secretion were retarded for a period of approximately 28-32 weeks while antibody titres were greater than 1:1000. An implant and water-soluble vaccine (200 and 400 mg) is presently being tested in 2 year old colts. Testicular dimensions and testosterone concentrations decreased following vaccination. Preliminary results indicate that the effects of the implant are reversible and last for approximately 30 weeks. The water-soluble vaccine produced effective antibodies for 10-19 weeks. Plasma testosterone of all colts was reduced to gelding levels (0.2 ng/mL) while antibody titres were greater than 1:1000. Semen evaluation, morphometric analysis and daily sperm production data indicate that the testes recovered normal function. These experiments are continuing and more definitive data on the vaccine and its reversibility will be available at their conclusion. Ovarian activity of the treated Fillies (200 and 400 mg) ceased soon after vaccination. Their progesterone concentrations have remained below 1 ng/mL for 20 weeks. The untreated control Fillies have continued to cycle normally as determined by ovarian ultrasonography and progesterone concentrations.
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Ovarian activity in Fillies treated with anabolic steroids prior to the onset of puberty.
Journal of reproduction and fertility. Supplement, 1991Co-Authors: K V Skelton, K. F. Dowsett, N P McmenimanAbstract:This study investigated the effects of zero, low (0.55), medium (1.1) and high (2.2 mg/kg LW) boldenone undecylenate on the reproductive physiology of sixteen Fillies from the ages of 7 to 11 months until 2 years. Ovarian activity measured by cross-sectional area, total number of ovulations, total number of follicles and the number of large follicles (greater than 30 mm in diameter) was significantly reduced by steroid treatments. Of Fillies that ovulated during the first breeding season, the age of first ovulation and the second breeding season was significantly delayed in the high dose group. Final clitoral diameters and the increase in clitoral diameter over the period of the study were significantly greater in the treated groups.
Adalgiza Souza Carneiro De Rezende - One of the best experts on this subject based on the ideXlab platform.
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effect of supplementation of sorghum silage in weanling Fillies during the dry period in brazil
Journal of Equine Veterinary Science, 2018Co-Authors: Diogo Felipe Da Silva Inacio, Rafael Henrique Prado Silva, Adalgiza Souza Carneiro De Rezende, Laydiane De Jesus Mendes, Suzana Maruch, Lilian Reis, ângela Maria Quintao Lana, Marília Martins Melo, Sarah L RalstonAbstract:Abstract Young horses reach nearly 90% of their final height in the first year of life. However, to achieve their genetic potential, it is necessary to receive adequate nutrition during this period of rapid growth. The objective of this study was to evaluate the effect of supplementation of sorghum silage during a period of limited pasture forage availability, on the body development, and health of Mangalarga Marchador (MM) weanling Fillies. Fourteen healthy MM 6-month-old Fillies were randomly assigned to one of two groups: GS (consuming silage) and GH (consuming grass hay (Cynodon spp) in addition to 1.5% of body weight (BW) in dry matter (DM) of a fortified corn-based concentrate (17% CP [crude protein]), which was fed in individual stalls divided into two feedings/day for both groups. After concentrate feedings, the experimental groups remained loose in drylot pens of 50 m2, where the assigned forages were fed ad libitum with free access to salt and water. Group feed intake of the forages was recorded. It was assumed they were consuming a forage:concentrate ratio of 50:50. To assess development, the animals were weighed and measured for height at the withers and croup, body length, girth, and cannon bone circumference. The physical condition of animals, including BW, rectal temperature, mucous membrane color, and body condition score were assessed as well as serum biochemical analyses of creatinine, urea, total protein, gamma glutaminotransferase, aspartate aminotransferase, alkaline phosphatase, glucose, magnesium, calcium, and phosphorus concentrations were evaluated. The weights, morphometric measurements, clinical evaluation, and blood collections were done on the first day and every 21 days during the 84 days trial period. The growth performance and serum were subjected to analysis of variance for repeated measures, factoring treatment, and collection period. Despite higher (P .05) on any of the development or health parameters measured. The use of sorghum silage as forage source for 84 days during the dry season had no negative impact on the body development and health of MM Fillies (6–9 months of age) that were also fed 1.5% BW of a commercial concentrate balanced for growth.
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the use of sorghum silage in feeding weanling horses body development
Livestock Science, 2017Co-Authors: Diogo Felipe Da Silva Inacio, Rafael Henrique Prado Silva, Adalgiza Souza Carneiro De Rezende, Laydiane De Jesus Mendes, Suzana Maruch, Kate Moura Da Costa Barcelos, ângela Quintao Lana, Marília Martins Melo, Sarah L RalstonAbstract:Abstract A correct and balanced nutrition has a great importance in the development of young horses. Weanlings should reach 90% of their final height at twelve months of age, and it is necessary that their rations allow them to reach their genetic potential during this critical growth period. The objective of this study was to compare the growth and development of weanling Fillies fed sorghum silage versus grass hay as the source of forage during the dry season. Fillies of the Mangalarga Marchador breed (MM) were weaned and were randomly allocated to one of 2 groups with 7 foals each: GS: fed sorghum silage (Sorghum bicolor cv. BRS655) or GH: fed Vaquero grass hay (Cynodon cv. CD90160 × cv. Mirage). Both groups were fed a commercial concentrate at the rate of 1.5% body weight (BW) in dry matter daily. The results show that the growth and development of the Fillies in both groups of this experiment was suitable for the breed. The use of sorghum silage for Fillies from 6 to 9 months of age that are also receiving 1.5% BW of a concentrate balanced for growing horses during the dry season allowed normal growth and development of MM Fillies.
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Intense Exercise and Aerobic Conditioning Associated with Chromium or L-Carnitine Supplementation Modified the Fecal Microbiota of Fillies
PloS one, 2016Co-Authors: Maria Luiza Mendes De Almeida, Adalgiza Souza Carneiro De Rezende, Walter Feringer, Julia Carvalho, Isadora Mestriner Rodrigues, Lilian De Rezende Jordão, Mayara Gonçalves Fonseca, Antonio De Queiroz Neto, J. Scott Weese, Marcio C. CostaAbstract:Recent studies performed in humans and rats have reported that exercise can alter the intestinal microbiota. Athletic horses perform intense exercise regularly, but studies characterizing horse microbiome during aerobic conditioning programs are still limited. Evidence has indicated that this microbial community is involved in the metabolic homeostasis of the host. Research on ergogenic substances using new sequencing technologies have been limited to the intestinal microbiota and there is a considerable demand for scientific studies that verify the effectiveness of these supplements in horses. L-carnitine and chromium are potentially ergogenic substances for athletic humans and horses since they are possibly able to modify the metabolism of carbohydrates and lipids. This study aimed to assess the impact of acute exercise and aerobic conditioning, associated either with L-carnitine or chromium supplementation, on the intestinal microbiota of Fillies. Twelve "Mangalarga Marchador" Fillies in the incipient fitness stage were distributed into four groups: control (no exercise), exercise, L-carnitine (10g/day) and chelated chromium (10mg/day). In order to investigate the impact of acute exercise or aerobic conditioning on fecal microbiota all Fillies undergoing the conditioning program were analyzed as a separate treatment. The Fillies underwent two incremental exercise tests before and after training on a treadmill for 42 days at 70-80% of the lactate threshold intensity. Fecal samples were obtained before and 48 h after acute exercise (incremental exercise test). Bacterial populations were characterized by sequencing the V4 region of the 16S rRNA gene using the MiSeq Illumina platform, and 5,224,389 sequences were obtained from 48 samples. The results showed that, overall, the two most abundant phyla were Firmicutes (50.22%) followed by Verrucomicrobia (15.13%). The taxa with the highest relative abundances were unclassified Clostridiales (17.06%) and "5 genus incertae sedis" from the phylum Verrucomicrobia (12.98%). There was a decrease in the phylum Chlamydiae and in the genus Mycobacterium after the second incremental exercise test. Intense exercise changed the community's structure and aerobic conditioning was associated with changes in the composition and structure of the intestinal bacterial population of Fillies. The intra-group comparison showed that chromium or L-carnitine induced moderate changes in the fecal microbiota of Fillies, but the microbiota did not differ from the control group, which was exercised with no supplementation. Fecal pH correlated positively with Simpson's index, while plasma pH correlated negatively. Our results show that exercise and aerobic conditioning can change in the microbiota and provide a basis for further studies enrolling a larger number of horses at different fitness levels to better understand the effects of exercise and training on the intestinal microbiota of horses.
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Skeletal Muscle Fiber Composition of Untrained Mangalarga Marchador Fillies
Journal of Equine Veterinary Science, 2016Co-Authors: Adalgiza Souza Carneiro De Rezende, Maria Luiza Mendes De Almeida, Lilian De Rezende Jordão, Mayara Gonçalves Fonseca, Antonio De Queiroz Neto, Flora Helena De Freitas D'angelis, Guilherme De Camargo Ferraz, José-luis L. RiveroAbstract:Abstract Mangalarga Marchador (MM) is the most important and numerous equine breed in Brazil. So far, no studies have been carried out on the breed's skeletal muscle composition, which is important to develop specific physical conditioning programs. To characterize the skeletal muscle fiber composition of young MM females, gluteus medius muscle biopsies were obtained from 13 Fillies between 2.5- and 3-year-old using a biopsy needle at 60-mm depth. Types I, IIA, and IIX fibers were determined by the metachromatic staining method of ATPase activity in myofibers using preincubation followed by incubation in alkaline medium. Relative frequency (%F), average cross-sectional area (CSA), and relative cross-sectional area (%CSA) of each muscle fiber type were determined. Considering %F, 29.5 ± 5.4% were type I, 40.3 ± 5.5% were type IIA, and 30.2 ± 5.9% were type IIX fibers. CSA of type I fibers was 2,633 ± 798 μm 2 , of type IIA was 3,407 ± 492 μm 2 , and of type IIX was 5,856 ± 1,237 μm 2 . %CSA was composed of 19.7 ± 4.9% of type I fibers, 35.4 ± 4.7% of type IIA, and 44.9 ± 7.4% of type IIX. The gluteus medius muscle of untrained MM Fillies was predominantly composed of type IIA fibers, but the highest total relative area was occupied by type IIX fibers, suggesting moderate aptitude to the oxidative and glycolytic metabolisms.
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chromium or l carnitine supplementation during an aerobic conditioning program mildly modified the energy metabolism biomarker response in mangalarga marchador Fillies
Livestock Science, 2015Co-Authors: Mayara Gonçalves Fonseca, Adalgiza Souza Carneiro De Rezende, Maria Luiza Mendes De Almeida, Lilian De Rezende Jordão, Antonio De Queiroz Neto, Jessica Lage, Juliana Moreira Andrade, Guilherme De Camargo FerrazAbstract:Chromium (Cr) and L-carnitine (LC) are potentially ergogenic substances for athletic horses since they are suggested to increase energy availability for the exercise and postpone the onset of fatigue. The present study aimed to assess the effect of supplementation with chelated chromium or L-carnitine on markers of energy metabolism in Mangalarga Marchador (MM) Fillies subjected to marcha treadmill tests. Thirteen Fillies were randomly assigned to three groups: Cr (n¼4; 10 mg/day chelated chromium), LC (n¼4; 10 g/day L-carnitine), and Control (n¼5; no supplementation). The research followed a completely randomized split-split-plot design. Each marcha test represented a plot, each nutritional supplementation group represented a split plot, and each moment in marcha tests represented a split-split-plot. The animals were exercised on the treadmill and automated walker on alternate days from Tuesday to Sunday for 42 days. Treadmill marcha tests took place on days 7 (Test 1), 21 (Test 2), and 42 (Test 3) with 5 min of warmup (1.7 m s � 1 ) followed for 30 min of marcha (3.5 m s � 1 and 3% slope). Heart rate (HR), blood lactate (Lac), blood glucose (Glu), and serum triglyceride levels (Trigl) were assessed before exercise and every 5 min during the marcha tests. The data underwent repeated measures analysis of variance and the means were compared by Tukey's test (Pr0.05). The Cr group had lower HR (Po0.05) at 20 min in Test 1; higher Lac (Po0.05) in Test 1 (from 10 to 35 min), Test 2 (at 10, 30, and 35 min), and Test 3 (at 10 min); and higher Glu (Po0.05) in Test 1 (from 20 to 35 min) and Test 2 (at 15 and 25 min). The LC group had higher (Po0.05) Glu in Test 1 (0 min) and lower Trigl (Po0.05) in Test 2 (at 25 and 30 min). As early as 21 days into conditioning (Test 2), a reduction (Po0.05) was found on HR, Lac, and Glu, however, Trigl was not affected by the conditioning (P40.05). The treadmill marcha tests showed a mild effect of chromium or L-carnitine supplementation on the energy metabolism markers of MM Fillies subjected to an aerobic conditioning program. LC or Cr supplementation associated with an aerobic conditioning program did Contents lists available at ScienceDirect
Kentaro Nagaoka - One of the best experts on this subject based on the ideXlab platform.
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Comparison of growth and endocrine changes in Thoroughbred colts and Fillies reared under different climate conditions
Journal of equine science, 2015Co-Authors: Hirotoshi Mizukami, Yasuo Nambo, Mutsuki Ishimaru, Tsuyoshi Suzuki, Hiroshi Naito, Kenji Korosue, Kentaro Akiyama, Kenji Miyata, Akira Yamanobe, Kentaro NagaokaAbstract:Development and endocrine changes in Thoroughbreds colts and Fillies were compared between those reared at two facilities of the Japan Racing Association, the Hidaka Training and Research Center (Hidaka) and Miyazaki Yearling Training Farm (Miyazaki). Thoroughbred colts and Fillies born in Japan between 2003 and 2010 were used. Each colt group and filly group was divided into 2 groups, respectively, and raised in Hidaka or Miyazaki for 7 months from September at 1 year old to April at 2 years old. For the growth parameters, the body weight, height at withers, and girth and cannon circumferences were measured once a month. For parameters of endocrine function, circulating prolactin, luteinizing hormone (LH), follicle-stimulating hormone (FSH), insulin-like growth factor-1 (IGF-1), testosterone, progesterone, and estradiol-17β levels were measured. Regarding growth, the rate of increase over the 7-month period was significantly higher in both colts and Fillies raised in Miyazaki than in Hidaka in all 4 parameters: body weight, height at withers, and girth and cannon circumferences. The endocrine changes of the colts and Fillies born in 2007 were as follows. In colts, although circulating prolactin tended to be higher in colts reared in Hidaka from October to April, circulating LH, FSH, testosterone, estradiol-17β and IGF-1 tended to be higher in colts reared in Miyazaki than in Hidaka, suggesting that the gonadotropin-releasing hormone-LH/FSH system and the growth hormone-IGF-1 system were more active in colts reared in Miyazaki as compared with those reared in Hidaka. In Fillies, circulating prolactin tended to be higher in Fillies reared in Hidaka in February and March, but no significant difference was noted in the serum LH, FSH, IGF-1, or progesterone level between the 2 groups. Circulating estradiol-17β tended to be higher in Fillies reared in Miyazaki than in Hidaka in October and November. Regarding ovarian function, the initial ovulation occurred by the end of March in 2 (16.7%) of 12 Fillies reared in Hidaka and 7 (38.9%) of 18 Fillies reared in Miyazaki, suggesting that the ovarian function was more active in Fillies reared in Miyazaki as compared with those reared in Hidaka. Based on these findings, it was clarified that development of the body and gonads was faster in Miyazaki compared with Hidaka in both colts and Fillies.
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Effects of an extended photoperiod on gonadal function and condition of hair coats in Thoroughbred colts and Fillies
Journal of equine science, 2015Co-Authors: Hirokazu Kunii, Yasuo Nambo, Mutsuki Ishimaru, Fumio Sato, Kentaro Nagaoka, Atsushi Okano, Akira Matsui, Yo Asai, Kazuki Fujii, WatanabeAbstract:The effects of an extended photoperiod (EP) in Thoroughbreds colts and Fillies from winter at one year old to spring at two years old on the gonadal functions, coat condition, and endocrine changes were investigated. Sixty-two Thoroughbreds (31 colts and 31 Fillies) reared in the Hidaka Training and Research Center (Hidaka), Japan Racing Association were used. Thirty of them (15 colts and 15 Fillies) were reared under EP conditions from December 20 to April 10, and the remaining 32 horses were reared under natural light alone as a control group. For EP, a 100-watt white bulb was set near the ceilings of stalls, and lighting conditions of 14.5-hr light and 9.5-hr dark periods were established. Blood was collected from the jugular vein once a month from October at one year old to February at two years old in both colts and Fillies, and then twice a month in colts and weekly in Fillies after March, and the coat condition was evaluated in January and April in 56 horses. To investigate endocrine changes, the plasma concentrations of prolactin, luteinizing hormone (LH), follicle-stimulating hormone (FSH), immunoreactive (ir-) inhibin, testosterone, estradiol-17β and progesterone were measured. No significant difference was noted in the coat condition between the two groups in January, but they changed from winter to summer coats (molting of winter coats) in April in the EP group compared with the control group. Regarding endocrine changes, the plasma concentrations of prolactin, FSH, ir-inhibin and testosterone were significantly higher in the EP colts than in the control group from January to April. The plasma concentrations of LH tended to rise in the EP colts from January to April compared with the control group. In the EP Fillies, the plasma concentrations of prolactin, LH, ir-inhibin, estradiol-17β and progesterone were significantly higher during January and April, but a significantly high level of FSH was noted in the control than EP group in January. The ovulation day was advanced in the EP Fillies compared with the control group. The present study clearly demonstrated that EP treatment during rearing advanced the molting of winter coats in both colts and Fillies. These results suggested to be due to the action of prolactin being increased by EP treatment. In addition, EP treatment stimulated the hypothalamus-pituitary-gonadal axis even in yearlings, and advanced ovulation in Fillies. Since EP treatment-induced changes in the yearlings were within the physiological range, and the method is safe and simple, EP treatment may be an effective technique in horse husbandry.
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promoting effects of an extended photoperiod treatment on the condition of hair coats and gonadal function in thoroughbred weanlings
Journal of Equine Science, 2015Co-Authors: Takehiro Harada, Yasuo Nambo, Mutsuki Ishimaru, Fumio Sato, Kentaro Nagaoka, Gen WatanabeAbstract:The effects of an extended photoperiod (EP) treatment (14.5 hr light, 9.5 hr dark) on Thoroughbred colts and Fillies from December 25 at 7–9 months old to the following May at 12–14 months old on coat condition and gonadal functions were investigated. Coat condition was evaluated in April. The colts and Fillies in the EP treatment group changed from winter to summer coats (molting of winter coats), whereas those in the control group did not. To determine the day of first ovulation, the plasma concentrations of progesterone were measured once a month in Fillies. The day of first ovulation was advanced in the EP treatment Fillies compared with the control Fillies. The present study clearly demonstrated that the EP treatment advanced the molting of winter coats and advanced ovulation in Fillies, even in weanlings.
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different effects of an extended photoperiod treatment on growth gonadal function and condition of hair coats in thoroughbred yearlings reared under different climate conditions
Journal of Equine Science, 2015Co-Authors: Tsuyoshi Suzuki, Yasuo Nambo, Mutsuki Ishimaru, Hirotoshi Mizukami, Hiroshi Naito, Kenji Korosue, Kentaro Akiyama, Kenji Miyata, Kentaro NagaokaAbstract:One- to two-year-old Thoroughbred colts and Fillies being reared in Miyazaki (warm climate) and Hidaka (cold climate), Japan, were administered extended photoperiod (EP) treatment between December 20 and the following April 10, and its effect on growth, endocrine changes, gonadal activation, and hair coat condition was investigated. In colts reared in Miyazaki, no effect of EP treatment was noted on the growth indices, including body weight (BW), height at withers (HW), girth, and cannon circumference (CC), whereas the BWs and CCs of Fillies were significantly higher in the EP treatment group than the control. In Hidaka, the BWs and HWs of colts and HWs of Fillies were significantly higher in the EP treatment group. Gonadal activation characterized by an increase in circulating hormone concentrations was earlier in the EP treatment group for Fillies reared in Miyazaki [luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (P4), and estradiol-17β (E2)] and in colts (LH, testosterone, and E2) and Fillies (LH, FSH, P4, and E2) reared in Hidaka. Regardless of sex and climate, prolactin was significantly higher in the EP treatment group, whereas insulin-like growth factor (IGF-I) was not. Initial ovulation occurred before April in more of the EP treatment group than the control regardless of the climate. Molting of the hair coat, examined in March, was advanced in the EP treatment group regardless of sex and climate. These results suggest that EP treatment may promote growth and gonadal activation in Fillies reared in Miyazaki and in colts and Fillies reared in Hidaka and that the effect may be mediated by prolactin.
M. Kosec - One of the best experts on this subject based on the ideXlab platform.
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Onset of puberty and duration of seasonal cyclicity in Lipizzan Fillies.
Equine veterinary journal, 2010Co-Authors: N. Cebulj-kadunc, V. Cestnik, M. KosecAbstract:Summary Reasons for performing study: The onset of puberty and duration of seasonal cyclicity in Lipizzan Fillies and young mares have been determined mostly by empirical data, but very little is known about the hormonal changes at puberty and during the seasonal cyclicity in this breed. Objectives: To determine the onset of puberty and the course of the cyclicity in young Lipizzan mares from age 1–4 years. Methods: Blood samples were collected twice a month for 2 years from 46 Lipizzan Fillies age 1–4 years. Progesterone concentrations, indicating ovarian activity, were measured using an EIA kit. Values above 6.4 nmol/l were taken to indicate luteal phase and those below 3.4 nmol/l, oestrus. Results: Fifty percent of Lipizzan Fillies entered puberty during the first spring after their birth at mean ± s.e. age 15.25 ± 0.31 months and 50% during the second spring, at age 25.2 ± 0.57 months. For several Fillies of all ages, manifesting anoestrus during the winter months, the oestrus started in March and reached a peak in June to September. The duration of the oestrus activity was age-dependent, at 2.37 ± 0.62 months in yearlings and 8.56 ± 0.46 months in Fillies age 4 years. In December, >50% of Fillies age 2–4 years still exhibited oestrus activity and some entered anoestrus in January the following year. A small proportion of Fillies age 3–4 years remained cyclic during the whole year, indicating that factors other than photoperiod can be involved in regulating seasonal cyclicity. Conclusions and potential relevance: Our results demonstrate the influence of seasonal factors on the onset of puberty and on the course of oestrus activity in the majority of Lipizzan Fillies. However, certain exceptions were also demonstrated but reasons for the prolonged periods of oestrus activity in some Lipizzan Fillies were not identified, and the role of the hormone leptin should be studied in future investigations.
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Serum Leptin Concentrations in Lipizzan Fillies
Reproduction in domestic animals = Zuchthygiene, 2008Co-Authors: N. Cebulj-kadunc, M. Kosec, V. CestnikAbstract:Contents To determine seasonal changes in circulating leptin concentrations, as well as leptin fluctuations in various patterns of seasonal ovarian activity, blood samples were taken in 107 Lipizzan Fillies aged 1–4 years over the whole year from January to December. Serum concentrations were measured in samples obtained once a month (leptin) or twice a month (progesterone), and evaluated with respect to the age of animals (yearlings, 2-, 3- and 4-year olds) and the pattern of ovarian activity (anoestrous, seasonal cycle, prolonged cyclicity, continuous cyclicity). The mean and monthly leptin concentrations in 3- and 4-year olds were significantly higher than in yearlings and 2-year olds (p 0.05).