250 Effect of Pre- and Post-ai Nutrition on Ovarian Dynamics, Steroidogenesis, and Expression of Estrus in Beef Heifers

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 131-131
Author(s):  
Kaitlin M Epperson ◽  
Jerica J Rich ◽  
Abigail L Zezeski ◽  
Saulo Menegatti Zoca ◽  
Julie Walker ◽  
...  
Keyword(s):  
Body Weight ◽  
Ovarian Function ◽  
Plasma Concentrations ◽  
Nutrient Restriction ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Follicle Diameter ◽  
Before And After ◽  
Follicle Size ◽  
Dietary Treatments

Abstract The objective of this study was to evaluate nutrition before and after artificial insemination (AI) on follicular dynamics, expression of estrus, and steroidogenesis. Seventy-nine beef heifers were randomly assigned to one of two dietary treatments (High;155% and Low;86% of maintenance energy) 30d prior to AI. Estrus was synchronized (PG 6-d CIDR protocol) and heifers received AI (d0) 8 to 12h following onset of estrus. On d0, heifers were randomly reassigned diets generating four Pre-x-Post-AI nutritional treatments; High-High (HH, n = 20), High-Low (HL, n = 20), Low-High (LH, n = 19), and Low-Low (LL, n = 20). Heifers remained on new diet treatments until embryo collection (flush; d7-8). Blood samples were collected daily from d-3 to d0, and on d1, 3, 5, 7 and 8 for plasma concentrations of estradiol (E2) and progesterone (P4). Dominant follicle diameter was evaluated on d-3 and d0, and CL diameter was recorded at flush. Statistical analyses were completed in SAS using the MIXED (body weight, E2, P4), GLIMMIX (expression of estrus), and GLM (ovarian parameters, interval to estrus) procedures. There were Pre-AI (P < 0.0001) and Post-AI by time (P < 0.0001) interactions on body weight; heifers in high and low treatments gained and lost weight, respectively, during both periods. Estradiol concentrations increased (P < 0.0001) from d-3 (2.18±0.15pg/mL) to d0 (6.05±0.04pg/mL). Pre-AI diet increased the proportion of heifers in estrus (80±6.3% vs. 59±7.9%; P = 0.05), and dominant follicle size (11.7±1.42mm vs. 10.68±1.33mm; P = 0.0016) in High vs. Low, respectively. Additionally, High Pre-AI heifers had greater P4 after AI compared to Low Pre-AI heifers (4.85±0.37ng/mL vs. 3.53±0.38ng/mL; P = 0.015). Post-AI treatment did not influence concentrations of P4 (P = 0.88). There was no effect of Pre, Post or Pre-x-Post-AI treatment on initial follicle size, follicle growth rate, E2 concentrations, interval to estrus, or CL size at flush (P > 0.10). In conclusion, nutrient restriction before AI negatively impacted ovarian function, steroidogenesis, and expression of estru.

scholarly journals The Effect of A PRID®Delta-Based Estrus Synchronization Protocol On Pregnancy Rates In Cows With No Estrus Symptoms

2022 ◽  
Author(s):  
Murat Can Demir ◽  
Cihan Kaçar ◽  
Umut Çağın Arı ◽  
Semra Kaya ◽  
Oğuz Merhan ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Prostaglandin F2α ◽  
Pregnancy Rates ◽  
Dominant Follicle ◽  
Serum Progesterone ◽  
Blood Samples ◽  
Follicle Diameter ◽  
Follicle Size ◽  
Equine Chorionic Gonadotropin

Abstract The present study aimed to determine the effects of progesterone-based gonadotropin-releasing hormone (GnRH), prostaglandin F2α (PGF2α), and equine chorionic gonadotropin (eCG) injections on progesterone profiles and pregnancy rates in cows with no estrus symptoms within 60 days after parturition. A total of 80 cows were included in the study. All animals had the progesterone-releasing device PRID®Delta placed intravaginally for nine days with an injection of GnRH. On the eighth day, PGF2α was injected, and PRID®Delta was removed from the vagina on day nine. Artificial insemination was carried out 60 hours after PRID®Delta removal. In half of the animals (n = 40), 600 IU of eCG was injected when PRID®Delta was removed on the ninth day before artificial insemination 60 hours later. Blood samples were taken from the tail vein on days 0 and 8 to determine progesterone levels. The pregnancy rate in the group that received eCG was 37.5%, while it was 27.5% in those that did not (P = 0.4). While the dominant follicle diameter was 15.5 mm in cows injected with eCG during timed artificial insemination, the follicle diameter was 12.4 mm in cows with no eCG injection (P <0.001). There were no differences in serum progesterone values in blood samples taken until the time of artificial insemination. However, progesterone values in the blood taken during artificial insemination were 0.94 ng/ml in the eCG- group and 0.72 ng/ml in the eCG+ group (P <0.05). As a result, it was determined that eCG injections, in addition to progesterone-based GnRH and PGF2α applications, increased the pregnancy rates in cows without symptoms of estrus. The dominant follicle diameter was larger in cows treated with eCG during artificial insemination; however, follicle size did not increase the pregnancy rate.

Effects of extending the length of pro-oestrus in an oestradiol- and progesterone-based oestrus synchronisation program on ovarian function, uterine environment and pregnancy establishment in beef heifers

2018 ◽  
Vol 30 (11) ◽  
pp. 1541 ◽  
Author(s):  
J. J. de la Mata ◽  
R. Núñez-Olivera ◽  
F. Cuadro ◽  
D. Bosolasco ◽  
V. de Brun ◽  
...  
Keyword(s):  
Ovarian Function ◽  
Progesterone Receptors ◽  
Fixed Time ◽  
Conventional Group ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Serum Progesterone ◽  
Ovulatory Follicle ◽  
Sexual Steroid ◽  
Uterine Environment

The aim of the present study was to investigate the effects of a strategy for extending pro-oestrus (the interval between luteolysis and ovulation) in an oestrus synchronisation protocol (named J-Synch) in beef heifers on follicular growth, sexual steroid concentrations, the oestrogen receptor ERα and progesterone receptors (PR) in the uterus, insulin-like growth factor (IGF) 1 and pregnancy rates. In Experiment 1, heifers treated with the new J-Synch protocol had a longer pro-oestrus period than those treated with the conventional protocol (mean (± s.e.m.) 93.7 ± 12.9 vs 65.0 ± 13.7 h respectively; P < 0.05). The rate of dominant follicle growth from the time of progesterone device removal to ovulation was greater in heifers in the J-Synch than conventional group (P < 0.05). Luteal area and serum progesterone concentrations were greater in the J-Synch Group (P < 0.05) for the 12 days after ovulation. Progesterone receptor (PGR) staining on Day 6 after ovulation in the uterine stroma was lower in the J-Synch than conventional group (P < 0.05), and the expression of PR gene (PGR) and IGF1 gene tended to be lower in J-Synch-treated heifers (P < 0.1). In Experiment 2 (n = 2349), the pregnancy rate 30–35 days after fixed-time AI (FTAI) was greater for heifers in the J-Synch than conventional group (56.1% vs 50.7% respectively). In conclusion, our strategy for extending pro-oestrus (i.e. the J-Synch protocol) significantly improves pregnancy establishment in beef heifers. This improvement was related to an increased rate of growth of the dominant ovulatory follicle, greater progesterone concentrations during the ensuing luteal phase and different uterine patterns of PGR and IGF1, which may have favoured embryo development and pregnancy establishment.

109 Pre-synchronization and reutilization of progesterone devices during a 6-day CO-Synch protocol for fixed-time artificial insemination in beef heifers

2021 ◽  
Vol 33 (2) ◽  
pp. 161
Author(s):  
E. R. Canadas ◽  
B. J. Duran ◽  
G. Machado ◽  
A. Nall ◽  
S. E. Battista ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Mixed Models ◽  
Generalized Linear Mixed Models ◽  
Fixed Time ◽  
P Value ◽  
Beef Heifers ◽  
Follicle Diameter ◽  
Follicle Size ◽  
Gonadotrophin Releasing Hormone ◽  
Intravaginal Device

Ovulatory response to the initial gonadotrophin-releasing hormone (GnRH) of the CO-Synch protocol is affected by circulating progesterone (P4) and follicle size. In addition, heifers that ovulate to the initial GnRH treatment have greater fertility after AI. Thus, this study determined the effect of (1) presynchronization (Presynch) before a 6-day CO-Synch protocol and (2) circulating [RCE1] (P4) on ovulatory response, oestrus expression, and pregnancies per AI (P/AI) in beef heifers. Yearling beef heifers (n=233) at three locations were randomly assigned in a 2×2 factorial design to the following treatments: (1) Presynch+6-day CO-Synch with a new P4 device; (2) Presynch+6-day CO-Synch with a once-used P4 device; (3) 6-day CO-Synch with a new P4 device; and (4) 6-day CO-Synch with a once-used P4 device. Presynch consisted of insertion of a new P4 intravaginal device (1.38g of P4) on Day −17 and removal of P4 device on Day −11 concurrently with 500µg of cloprostenol sodium (PGF). On Day −9, all heifers received either a new (New) or once-used (Used) CIDR and 100µg of gonadorelin acetate (GnRH). Six days later (Day −3), CIDRs were removed, 1000µg of PGF was administered and an oestrous detection patch applied (Estrotect). At 72h after CIDR removal, AI was performed concurrently with administration of 100µg of GnRH. Pregnancy was determined by transrectal ultrasonography 31 days after AI. A subset of heifers (n=155) was examined on Day −9 and Day −3 by ultrasonography to determine ovulation to Day −9 GnRH. Data were analysed using generalized linear mixed models (SAS 9.4; SAS Institute Inc.). Presynch heifers had larger follicle diameter on Day −9 (12.7±0.3 vs. 10.1±0.3 mm; P&lt;0.001), greater ovulatory response to Day −9 GnRH (82.5%; 66/80 vs. 56%; 42/75; P&lt;0.001), greater expression of oestrus (90.6%; 106/117 vs. 78.4%; 91/116; P&lt;0.02), and earlier oestrus (49.8±1 vs. 53.1±1 h; P&lt;0.01) compared with controls. There was a treatment×CIDR interaction on oestrous expression, such that a lesser (P&lt;0.05) percentage of control heifers with new CIDR expressed oestrus compared with all other groups (Table 1). Heifers with a used CIDR during the 6-day CO-Synch tended (P=0.08) to have greater P/AI (52.1%; 61/117) than those with a new CIDR (40.5%; 47/116). In conclusion, presynchronization before initiation of a 6-day CO-Synch increased follicle diameter, enhanced ovulatory response and oestrous expression, but did not affect fertility. The earlier onset of oestrus in presynchronized heifers suggests that the timing of AI may need to be modified. Table 1. Oestrous expression and pregnancy per AI (P/AI) in beef heifers with or without presynchronization and treated with a new or used CIDR during a 6-day CO-Synch Treatment CIDR Oestrus (%; n/n) Time of oestrus (h) P/AI (%; n/n) Control New 67.8a (40/59) 53.7±1.5a 33.9 (20/59) Used 89.5b (51/57) 52.7±1.6a 50.9 (29/57) Presynch New 94.7b (54/57) 50.9±1.4b 47.4 (27/57) Used 86.7b (52/60) 48.7±1.3b 53.3 (32/60) P-value Treatment 0.03 0.01 0.21 CIDR 0.62 0.19 0.08 Interaction 0.003 0.75 0.38 a,bValues with different superscripts differ (P&lt;0.05).

scholarly journals Effects of oestradiol and progesterone on secretion of gonadotrophins and health of first wave follicles during the oestrous cycle of beef heifers

Reproduction ◽  
2002 ◽  
pp. 531-541 ◽  
Author(s):  
EJ Austin ◽  
M Mihm ◽  
AC Evans ◽  
JL Ireland ◽  
JJ Ireland ◽  
...  
Keyword(s):  
Growth Factor ◽  
Antral Follicle ◽  
Follicle Development ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Follicle Diameter ◽  
Oestradiol Benzoate ◽  
Lh Release ◽  
Follicle Selection ◽  
Intravaginal Device

Antral follicle development in cattle is initially FSH dependent and then LH dependent. The aim of the present study was to determine the effects of oestradiol- and progesterone-induced suppression of FSH and LH on growth and differentiation of first wave follicles. Cyclic heifers (n = 45, n = 6-10 per group) received the following i.m. injections or treatments beginning 30 h after oestrus: (i) saline (controls); (ii) 0.75 mg oestradiol benzoate (ODB); (iii) insertion of a progesterone-releasing intravaginal device (PRID) for 42 h (progesterone); (iv) 0.75 mg oestradiol benzoate plus PRID (ODB plus progesterone); (v) 0.75 mg ODB plus injection of 1 mg Ovagen(TM) at 33, 39 and 45 h after onset of oestrus (ODB plus FSH). In Expt 1, follicle development was monitored by ovarian ultrasonography once a day. In Expt 2, heifers were ovariectomized. Emergence of the first follicle wave and dominant follicle selection were delayed in ODB plus progesterone-treated heifers compared with controls. Interval to nadir FSH concentration was shorter in ODB-, progesterone- and ODB plus progesterone-treated heifers compared with controls. Frequency of LH pulses was unaffected in ODB- or ODB plus FSH-treated heifers, decreased in progesterone-treated heifers and further decreased in ODB plus progesterone-treated heifers. Intrafollicular oestradiol concentrations were lower in the largest follicle from ODB plus progesterone-treated heifers compared with control (66 h) heifers, but follicle diameter and concentrations of insulin-like growth factor binding proteins (IGFBPs) and inhibin forms were unaffected. Treatment with ODB decreased follicular oestradiol concentration in smaller follicles in the cohort. It is concluded that growing cohort follicles are uniformly responsive to increased FSH concentration but differentially responsive to suppressed FSH and LH release, which is consistent with an LH-mediated survival advantage of the largest follicle in the cohort before cessation of the growth of remaining follicles in the cohort occurs.

scholarly journals Relationship between metabolic hormones and ovulation of dominant follicle during the first follicular wave post-partum in high-producing dairy cows

Reproduction ◽  
2007 ◽  
Vol 133 (1) ◽  
pp. 155-163 ◽  
Author(s):  
Chiho Kawashima ◽  
Saori Fukihara ◽  
Mayumi Maeda ◽  
Etsushi Kaneko ◽  
Carlos Amaya Montoya ◽  
...  
Keyword(s):  
Blood Flow ◽  
Dairy Cows ◽  
Ovarian Function ◽  
Post Partum ◽  
Plasma Concentrations ◽  
Reproductive Hormones ◽  
Follicular Growth ◽  
Dominant Follicle ◽  
Follicular Wave ◽  
Igf I

Recent studies suggest that IGF-I is a crucial regulatory factor in follicular growth during earlypost-partumperiod. The aim of the present study was to determine in detail the changing profiles of metabolic and reproductive hormones in relation to ovulation of the dominant follicle (DF) of the first follicular wavepost-partumin high-producing dairy cows. Plasma concentrations of related hormones in 22 multiparous Holstein cows were measured from 4 weeks pre-partum to 3 weekspost-partum, and the development of DF was observed with colour Doppler ultrasound. Thirteen cows showed ovulation by 15.2 dayspost-partum. Anovulatory cows showed higher GH and lower IGF-I levels than those in ovulatory cows during the peri-partum period. Each DF developed similarly, and a clear blood flow in the follicle wall was observed despite ovulation or anovulation. In addition, detailed endocrine profiles were analyzed in 9 out of the 22 cows. Five cows showed an increase in plasma oestradiol-17β (E2) with follicular growth followed by E2 peak, LH surge and ovulation. In these cows, plasma IGF-I concentrations remained high until 10 dayspost-partumfollowed by a gradual decrease. Subsequently, the insulin level increased together with the E2 peak towards ovulation. These profiles were not observed in anovulatory cows. In conclusion, our data strongly support the concept that IGF-I and insulin represent ‘metabolic signals’ of the resumption of ovarian functionpost-partumin high-producing dairy cows. Moreover, we provide the first visual evidence that both ovulatory and anovulatory DFs of the first follicular wavepost-partumare similarly supplied with active blood flow.

scholarly journals Effects of a non-steroidal aromatase inhibitor on ovarian function in cattle

2012 ◽  
Vol 24 (4) ◽  
pp. 631 ◽  
Author(s):  
M. Jimena Yapura ◽  
Reuben J. Mapletoft ◽  
Jaswant Singh ◽  
Roger Pierson ◽  
Jonathan Naile ◽  
...  
Keyword(s):  
Aromatase Inhibitor ◽  
High Performance ◽  
Ovarian Function ◽  
Plasma Concentrations ◽  
Dominant Follicle ◽  
Follicular Wave ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Arrest Growth ◽  
Phosphate Buffered Saline

Effects of the non-steroidal aromatase inhibitor letrozole on ovarian function in cattle were determined. The hypothesis that letrozole would arrest growth of the dominant follicle, resulting in emergence of a new follicular wave at a predictable post-treatment interval, was tested. Heifers were assigned randomly to four groups 4 days after follicular ablation (~2½ days after wave emergence) and given intravenous doses of 500 (n = 9), 250 (n = 10), or 125 µg kg–1 (n = 10) letrozole or phosphate-buffered saline (controls; n = 10). Blood was collected and ovarian structures were monitored daily by transrectal ultrasonography. Plasma concentrations of LH and FSH were measured by radioimmunoassay; plasma concentrations of letrozole were determined by high-performance liquid chromatography tandem mass spectrometry. A single intravenous dose of letrozole did not induce regression of the dominant follicle present at the time of treatment, nor did it directly affect FSH release. Conversely, treatment with letrozole increased endogenous concentrations of LH and extended the lifespan of the dominant follicle, which delayed the next FSH surge and subsequent follicular wave emergence. Letrozole continues to have potential as a non-steroidal treatment for controlling ovarian function in cattle.

Presynch-Heatsynch: A New Approach to Improve Ovarian and Fertility Responses in Water Buffalo (Bubalus bubalis)

2021 ◽  
Author(s):  
Harmeet Singh Sandhu ◽  
Shahbaz Singh Dhindsa ◽  
Harpreet Singh ◽  
Mrigank Honparkhe ◽  
Prahlad Singh
Keyword(s):  
Fixed Time ◽  
Estradiol Benzoate ◽  
Bubalus Bubalis ◽  
Gnrh Analogue ◽  
Dominant Follicle ◽  
New Approach ◽  
Follicle Diameter ◽  
Group I ◽  
Follicle Size ◽  
Group Ii

Background: Standard estrus synchronization regimens resulted in variable outcomes in buffaloes. The present study evaluated ovarian and fertility responses following presynchronization in Heatsynch protocol administered in postpartum buffaloes. Methods: In group-I (Presynch-Heatsynch group, n = 30), PGF2α was administered on days -14 and -2. Then, GnRH analogue, PGF2α (Cloprostenol) and Estradiol benzoate were administered on day 0, 7 and 8, respectively followed by fixed-time artificial insemination (FTAI) 48 hours later. In group-II (Heatsynch group, n = 30), rest protocol was same, except that first two PGF2α injections were not administered. Result: The progesterone concentrations differed (P less than 0.01) between the two groups on days -2, 0 and 7. Post-treatment, progesterone profiles were also higher in pregnant compared to non-pregnant buffaloes in both the groups except on day 10. CL diameter differed (P less than 0.01) between groups on days -2, 0 and 7. It was larger in pregnant than non-pregnant buffaloes on day 7 in both the groups. Dominant follicle diameter remained larger on days -2, 0 and 8 in group-I than -II. Buffaloes getting pregnant had a larger (P less than 0.01) dominant follicle size on the day of FTAI in group-I than of group-II. Ovulatory response of 93.33 and 90.00% was observed in group-I and II. The conception rate was higher (66.66 vs. 40.00%; P less than 0.05) in group-I than Group-II. Presynchronization improved reproductive efficiency in Heatsynch treatment and may aid for better fertility in buffaloes.

115 Presynchronization and reutilization of progesterone devices during a 6-day CO-Synch protocol for fixed-time artificial insemination in beef heifers

2021 ◽  
Vol 33 (2) ◽  
pp. 165
Author(s):  
E. R. Canadas ◽  
B. Duran ◽  
G. Machado ◽  
A. Nall ◽  
S. E. Battista ◽  
...  
Keyword(s):  
Factorial Design ◽  
Artificial Insemination ◽  
Fixed Time ◽  
P Value ◽  
Beef Heifers ◽  
Follicle Diameter ◽  
Follicle Size ◽  
Gonadotrophin Releasing Hormone ◽  
Intravaginal Device ◽  
Second Use

Ovulatory response to the initial gonadotrophin-releasing hormone (GnRH) of the CO-Synch protocol is affected by circulating progesterone (P4) and follicle size. In addition, heifers that ovulate to initial GnRH treatment have greater fertility after AI. Thus, the aim of this study was to assess the effect of (1) presynchronization (Presynch) before a 6-day CO-Synch protocol and (2) P4 device reuse (new vs. second use) on ovulatory response, oestrous expression, and pregnancy per AI (P/AI) in beef heifers. Yearling beef heifers (n=233) were randomly assigned in a 2×2 factorial design to the following treatments: (1) Treatment (Presynch): (1a) Presynch+6-day CO-Synch with new P4 device; (1b) Presynch+6-days CO-Synch with a once-used P4 device; (2) Control (no Presynch): (2a) 6-day CO-Synch with new P4 device; (2b) 6-day CO-synch with once-used P4 device. Presynch consisted of insertion of a new P4 intravaginal device (CIDR, 1.38g of P4; Zoetis) on Day −17 and removal of the CIDR on Day −11 concurrently with 500µg of cloprostenol sodium. On Day −9, all heifers received either a new or once-used (used) CIDR and 100µg of gonadorelin acetate (GnRH, Parnell Inc.). Six days later (Day −3) CIDRs were removed, 1000µg of PGF was administered, and an oestrous detection patch applied (Estrotect, Rockway Inc.). At 72h after CIDR removal, 100µg of GnRH and AI using 3 different sires was performed. Pregnancy was determined by ultrasonography 31 days after AI. A subset of heifers (n=151) were examined on Day −9 and Day −3 by ultrasonography to assess ovulation to Day −9 GnRH. Data were analysed using GLIMMIX (SAS 9.4; SAS Institute Inc.). Presynch heifers had larger follicle diameter on Day −9 (12.7±0.3 vs. 10.4±0.3 mm; P&lt;0.0001), greater ovulatory response (84.6%; 66/78 vs. 52.05%; 38/73; P&lt;0.0001), greater oestrus expression (90.6%; 106/117 vs. 78.4%; 91/116; P=0.03), and expressed oestrus earlier (49.8±1.0 vs. 53.1±1.1 h; P=0.01) compared with controls. There was an interaction for treatment and CIDR on oestrous expression, whereas a lesser (P=0.003) percentage of control heifers with new CIDR showed oestrus compared with all other groups (Table 1). Heifers treated with a used P4 device tended (P=0.08) to have greater P/AI (52.1%; 61/117) than those with a new CIDR (40.5%; 47/116). In conclusion, presynchronization before initiation of a 6-day CO-Synch increased follicle diameter, ovulatory response, and oestrous expression, but did not affect fertility. The earlier onset of oestrus in Presynch heifers warrants further study on timing of AI. Table 1. Oestrous expression and pregnancy per AI (P/AI) in beef heifers with or without presynchronization and treated with a new or used CIDR Treatment CIDR Oestrus (%; n/n) Time of oestrus (h) P/AI (%; n/n) Control New 67.8a (40/59) 53.7±1.5a 33.9 (20/59) Used 89.5b (51/57) 52.7±1.6a 50.9 (29/57) Presynch New 94.7b (54/57) 50.9±1.4b 47.4 (27/57) Used 86.7b (52/60) 48.7±1.3b 53.3 (32/60) P-value Treatment 0.03 0.01 0.21 CIDR 0.62 0.18 0.08 Interaction 0.003 0.78 0.38 a,bValues with different superscripts differ (P &lt; 0.05).

The effect of diet and exercise on plasma metabolite and hormone concentrations in horses measured before and after exercise

2017 ◽  
Vol 13 (2) ◽  
pp. 97-104 ◽  
Author(s):  
R.B. Jensen ◽  
D. Blache ◽  
K.E. Bach Knudsen ◽  
D. Austbø ◽  
A.-H. Tauson
Keyword(s):  
Metabolic Response ◽  
Plasma Concentrations ◽  
Latin Square ◽  
Field Studies ◽  
Experimental Conditions ◽  
Diet And Exercise ◽  
Before And After ◽  
Dietary Treatments ◽  
Plasma Metabolite ◽  
Plasma Leptin

Exercise influences different endocrine and metabolic parameters, and information in the literature is sparse for some of these hormones and metabolites in the exercising horse. The aim of the present experiment was to study the metabolic response to exercise when feeding diets with varying carbohydrate composition (fibre and starch) under experimental conditions where diet and exercise were standardised and controlled. The response was investigated in a 4×4 Latin square design experiment using four Norwegian Coldblooded trotter horses. The dietary treatments were two fibre based diets, hay only and hay (85% of dry matter intake (DMI)) supplemented with molassed sugar beet pulp (mSBP) (15% of DMI), or two starch based diets of hay (68% of DMI) and barley (32% of DMI), and hay (68% of DMI), barley (26% of DMI) and mSBP (6% of DMI). Each diet was fed for 28 days; 16 days of adaptation followed by 12 days of data collection. 4 h after the morning feeding at 06:00 the horses performed a standardised exercise test (SET) lasting 45 min. Blood samples were taken before feeding the morning meal at 06:00, before the SET (10:00), after the SET (10:45) and after recovery from exercise (15:00), and plasma samples were analysed for relevant metabolites and hormones. Plasma leptin concentrations increased after exercise but were not affected by diet, whereas diet and exercise had no effect on the plasma concentrations of ghrelin and insulin like growth factor 1 (IGF-1). Furthermore, diet influenced the plasma concentrations of short-chained fatty acids (SCFA) more than exercise. The results provide important comparative information that can be useful in studies where diet and exercise cannot be controlled, e.g. in field studies.

scholarly journals Effects of prolonging the interval from progestin removal to prostaglandin F2α injection from 16 to 17 days in a long-term estrus synchronization protocol in beef heifers

2021 ◽  
Author(s):  
N Oosthuizen ◽  
G D Melo ◽  
G E Seidel ◽  
R L Stewart ◽  
L Rowden ◽  
...  
Keyword(s):  
Prostaglandin F2α ◽  
Fixed Time ◽  
Transrectal Ultrasonography ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Treatment Groups ◽  
Follicle Diameter ◽  
Randomized Design ◽  
Angus Heifers

Abstract To determine effects of delaying the injection of prostaglandin F2α (PGF) and fixed-time artificial insemination (TAI) in the 14-d CIDR-PG protocol, 1,049 Angus heifers at six locations were enrolled in a completely randomized design. Within location heifers were randomly assigned to one of two treatment groups: 1) PG16 (n = 518), heifers received a controlled internal drug release (CIDR) insert on d 0 for 14 d, a 25-mg injection of PGF 16 d after CIDR removal (Day 30), and a 100-µg injection of gonadotropin-releasing hormone concurrent with TAI 66 ± 2 h later; or 2) PG17 (n = 531), heifers were treated the same as PG16, however, PGF was administered 17 d after CIDR removal (Day 31), and heifers were TAI 66 ± 2 h later. Estrus detection patches were applied to a subset (n = 482) of heifers at the time of PGF administration and were examined for activation at TAI. Dominant follicle diameter was determined via transrectal ultrasonography at PGF administration and TAI in a subset of heifers (n = 116). Transrectal ultrasonography was performed to determine pregnancy rates to TAI (PR/AI) between 30 and 45 d after TAI. Estrus expression prior to TAI differed by treatment where PG17 heifers had greater (P &lt; 0.01) expression of estrus than PG16 heifers (57.8 ± 6.1 vs. 43.4 ± 6.1%, respectively). Nevertheless, dominant follicle diameters at PGF and at TAI were similar (P ≥ 0.59) between PG16 and PG17 heifers. In addition, PR/AI did not differ (P = 0.29) between PG16 and PG17 treatments (50.5 ± 3.2 vs. 45.7 ± 3.1%, respectively). Results of this experiment indicate that delaying the injection of PGF and TAI in the 14-day CIDR-PG protocol increased estrus expression prior to TAI yet did not improve fertility in beef heifers.

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