11 EFFECTS OF CIDR-BASED PRESYNCHRONIZATION AND eCG ON FERTILITY FOR A GnRH-BASED TIMED-AI PROTOCOL IN BEEF CATTLE

2006 ◽  
Vol 18 (2) ◽  
pp. 114 ◽  
Author(s):  
M. Colazo ◽  
J. Small ◽  
J. Kastelic ◽  
H. Davis ◽  
D. Ward ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Factorial Design ◽  
Pregnancy Rate ◽  
Animal Health ◽  
Beef Cows ◽  
Beef Heifers ◽  
Treatment Control ◽  
Pfizer Animal Health ◽  
Exogenous Progesterone ◽  
To Receive

The objectives were to determine the effects of presynchronization and eCG on fertility for a GnRH-based timed-AI (TAI) protocol in beef cattle. Previously autoclaved once-used CIDR inserts (Colazo et al. 2004 Anim. Reprod. Sci. 81, 25-34) were used for experimental purposes so that all cattle had equivalent exogenous progesterone after Day 7 in Experiment 1, and to induce GnRH-responsive follicles in Experiment 2. In Experiment 1, 12-15 month old beef heifers (n = 447) were used (three locations, A, B, and C). On Day 0, half received a new CIDR insert (Pfizer Animal Health, Montreal, Quebec, Canada) and 500 �g of cloprostenol i.m. (PGF: Estrumate; Schering-Plough Animal Health, Pointe-Claire, Quebec, Canada). On Day 7, the remainder received an autoclaved once-used CIDR and all received 100 �g of GnRH i.m. (Cystorelin; Merial Canada, Inc., Victoriaville, Quebec, Canada). On Day 14, CIDR inserts were removed, PGF was given to all heifers, and heifers were given either 300 IU eCG i.m. (Pregnacol; Bioniche Animal Health, Belleville, Ontario, Canada) or no treatment (2 � 2 factorial design). On Day 16 (54-56 h after CIDR removal and PGF administration), heifers were given 100 �g of GnRH i.m., concurrent with TAI. Transrectal ultrasonography was done on Day 0 to assess ovarian structures, and on approximately Day 50 (range, 44-69) to confirm pregnancy. Overall, 72.7% of heifers were puberal on Day 0 (150/150, 5/37, and 170/260 for locations A, B, and C, respectively; P < 0.001). Pregnancy rate was affected (P < 0.001) by location (27.3, 62.2, and 51.1% for the three locations, respectively) but was not affected (P = 0.3) by puberal status at locations B and C. Pregnancy rate was not affected (P = 0.5) by presynchronization, but tended (P = 0.1) to be reduced by eCG treatment (40.4 vs. 47.7%, respectively). In Experiment 2, lactating crossbred beef cows (n = 411), 2-12 years of age were randomly allocated to receive either a previously used, autoclaved CIDR for 7 days and 25 mg of dinoprost i.m. (PGF: Lutalyse; Pfizer Animal Health) or no treatment (control; Day 0). At CIDR removal (Day 7), all cows received 100 �g of GnRH. On Day 14, all cows received PGF and were allocated to receive either 400 IU of eCG i.m. or no treatment (2 � 2 factorial design). On Day 16 (54-56 h after PGF), cows were given 100 �g of GnRH concurrent with TAI. Transrectal ultrasonographic examinations were done on approximately 65 cows in each group on Days 0, 7, and 14 to assess ovarian structures and on all cows on Day 42 to confirm pregnancy. Overall, 88.8% of cows had a corpus luteum (CL) on Day 0. Presynchronization increased both the proportion of cows that ovulated to GnRH treatment on Day 7 (76.7 vs. 55.0%; P < 0.001) and pregnancy rate (58.2 vs. 45.4%; P = 0.03) for cows that had received a CIDR vs. control cows. However, eCG treatment did not affect pregnancy rate (P = 0.3) in either group. In summary, presynchronization with a used CIDR and PGF prior to a Cosynch protocol increased ovulation rate to the first GnRH treatment and pregnancy rate in cows but not in heifers. In a GnRH-based TAI protocol, treatment with eCG had no significant effect on fertility in cows, but tended to decrease fertility in heifers.

scholarly journals 18 STRATEGIES TO IMPROVE FERTILITY WITH COSYNCH-CIDR PROTOCOLS IN BEEF CATTLE

2005 ◽  
Vol 17 (2) ◽  
pp. 159 ◽  
Author(s):  
R. Mapletoft ◽  
M. Colazo ◽  
L. Siqueira ◽  
J. Small ◽  
M. Rutledge ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Animal Health ◽  
Beef Cows ◽  
Preovulatory Follicle ◽  
Beef Heifers ◽  
Treatment Control ◽  
Pfizer Animal Health ◽  
Follicle Size ◽  
D 12 ◽  
To Receive

Two experiments were designed to evaluate strategies to improve fertility with Cosynch-CIDR protocols in cattle. The first experiment investigated the effect of low levels of progesterone prior to a Cosynch-CIDR protocol. On Day 0, lactating beef cows (n = 34) and heifers (n = 37) were placed in two groups to receive 500 μg cloprostenol (PGF; Estrumate, Schering-Plough Animal Health, Pointe-Claire, Quebec, Canada) or a twice-used CIDR (Bioniche Animal Health, Belleville, Ontario, Canada) for 5 days (Pretreatment) or no treatment (Control). On Day 5, used CIDRs were removed and all cattle received a new CIDR (Pfizer Animal Health, Montreal, Quebec, Canada) and 100 μg GnRH (Cystorelin, Merial Canada Inc, Victoriaville, Quebec, Canada). On Day 12, CIDR were removed and PGF was given. A second GnRH was given concurrent with timed AI (TAI) on Day 14 (54–56 h after PGF). Cattle were examined by transrectal ultrasonography for CL and follicle development, and for confirmation of pregnancy (Days 42 to 49). Diameter of the dominant follicle on Day 5 was larger and more variable in cows than in heifers (15.5 ± 5.6 vs. 11.4 ± 3.5 mm, respectively; means, P < 0.001; variance, P < 0.003), and tended to be larger in the Pretreatment group (14.3 ± 4.9 vs. 12.6 ± 5.2 mm; P = 0.13). More Pretreated (60.0%) than Control (36.1%) cattle (P < 0.005), and more cows (64.7%) than heifers (32.4%; P < 0.03) ovulated following the first GnRH. At the time of TAI, 5 (13.5%) heifers had already ovulated (P < 0.03). Diameter of the preovulatory follicle was affected by parity (P < 0.001), but not Pretreatment (P = 0.4), and tended to be larger in heifers that became pregnant (P = 0.13). Pregnancy rate was not affected by parity (P = 0.71), or pretreatment (P = 0.34); pretreatment tended to increase pregnancy rate in heifers (63.2 vs. 38.9%; P = 0.19). The second experiment evaluated the use of eCG in a Cosynch-CIDR protocol in beef heifers. Beef heifers (n = 127) were fed 0.5 mg/head/day of MGA (Pfizer Animal Health) for 15 d; 12 d after the last feeding (designated as Day 0) heifers received a CIDR and 100 μg GnRH. On Day 7, CIDR were removed, and heifers received PGF, and were randomly placed in 2 groups to receive 300 IU of eCG (Pregnacol; Bioniche Animal Health) or no treatment (Control). On Day 9 (54–56 h after PGF), all heifers received 100 μg GnRH, concurrent with TAI. Ultrasonographic examinations were done as in the first experiment. Overall, 79.5% of the heifers had a CL, and 9.4% had a luteinized follicle on Day 0. Seventy-eight heifers (61.4%) ovulated following the first GnRH, and those that ovulated had a less variable preovulatory follicle size than those that did not (13.7 ± 1.7 vs. 13.8 ± 2.3 mm; means, P = 0.76; variance, P < 0.01). However, there was no difference in preovulatory follicle size (P = 0.63), or pregnancy rate (49.2 vs. 53.1%; P = 0.7) for eCG-treated vs. Control heifers. In summary, pretreatment with a twice-used CIDR plus PGF increased the proportion of cattle that ovulated to the first GnRH, but not preovulatory follicle size or fertility in cows; fertility tended to be improved in heifers. Treatment with eCG did not increase preovulatory follicle size or fertility in heifers subjected to an Cosynch-CIDR protocol.

scholarly journals 13 EFFECTS OF PRESYNCHRONIZATION WITH A USED CIDR, AND TREATMENT WITH eCG ON FERTILITY IN LACTATING COWS SUBJECTED TO A COSYNCH PROTOCOL

2005 ◽  
Vol 17 (2) ◽  
pp. 156 ◽  
Author(s):  
M. Colazo ◽  
M. Rutledge ◽  
J. Small ◽  
J. Kastelic ◽  
L. Siqueira ◽  
...  
Keyword(s):  
Factorial Design ◽  
Pregnancy Rate ◽  
Animal Health ◽  
Beef Cows ◽  
Preovulatory Follicle ◽  
Dominant Follicle ◽  
Treatment Control ◽  
Lactating Cows ◽  
Follicle Size ◽  
To Receive

The objectives were to investigate the effects of pretreatment with a used CIDR on follicle size and ovulation rate in cows after an injection of GnRH, and treatment with eCG at the time of PGF on preovulatory follicle size and fertility in cows subjected to a Cosynch protocol. Lactating crossbred beef cows (n = 292), 2 to 12 years of age were allocated to two groups to receive either a used CIDR (Bioniche Animal Health; Belleville, Ontario, Canada) for 15 days or no treatment (Control). At CIDR removal (Day 0), all cows received 100 μg of GnRH i.m. (Cystorelin, Merial Canada Inc., Victoriaville, Quebec, Canada). On Day 7, all cows received 500 μg of cloprostenol i.m. (PGF; Estrumate, Schering-Plough Animal Health, Pointe-Claire, Quebec, Canada) and were further allocated to receive either 400 IU of eCG i.m. (Pregnacol; Bioniche Animal Health) or no treatment (2 × 2 factorial design; n = 73 per group). On Day 9 (54 h after PGF), cows were given 100 μg of GnRH i.m., concurrent with timed AI (TAI). Transrectal ultrasonographic examinations were done on a subset of approximately 40 cows in each group on Days −15, 0, 7, and 9 to assess ovarian structures, and on all cows on Day 37 to confirm pregnancy. Data were analyzed by SAS CATMOD and ANOVA. Overall, 53% of cows had a CL present on Day −15 (P = 0.23). At first GnRH (Day 0), fewer CIDR-treated cows than Control cows had a CL (15.2 vs. 85.0%, respectively; P < 0.001), while mean (± SEM) diameters of the dominant follicle were larger in CIDR-treated cows (18.2 ± 0.4 vs. 13.8 ± 0.4 mm, respectively; P < 0.001). Moreover, the proportion of cows that ovulated following the first GnRH was higher (P < 0.001) in CIDR-treated (75.0%) than Control (48.7%) cows. Eight (10.0%) cows presynchronized with a CIDR did not ovulate and had a luteinized follicle (31.7 ± 1.9 mm) at the time of PGF. Although CIDR-treated cows had larger (P < 0.002) dominant follicles than Control cows on Day 9 (16.6 ± 0.3 vs. 15.2 ± 0.3 mm), presynchronization did not affect fertility (53.4 vs. 54.1%, respectively). However, diameter of the dominant follicle at TAI in cows that became pregnant was smaller in CIDR-treated vs. Control cows (15.3 ± 0.3 vs. 16.6 ± 0.3; P < 0.005). Treatment with eCG on Day 7 did not affect (P = 0.17) the diameter of the dominant follicle at TAI, but tended (P = 0.06) to increase pregnancy rate (58.9 vs. 48.6%). Furthermore, pregnancy rate tended to be higher (P = 0.08) in Control cows given eCG (47/73, 64.4%) than in the Control- (32/73, 43.8%), CIDR- (39/73, 53.4%) or CIDR/eCG- (39/73, 53.4%) treated cows. In addition, pregnancy rate was affected by parity; 2-yr-old cows had a lower (P < 0.04) pregnancy rate than older cows (42.9, 58.7, and 58.2% for 2, 3–4, and >5 years, respectively). Treatment with eCG increased pregnancy rate by 33% (P < 0.03) in 2-yr-old Control cows. In summary, presynchronization with a used CIDR prior to a Cosynch protocol increased the proportion of cows responding to the first GnRH. Although CIDR-treated cows had a smaller dominant follicle at TAI, pregnancy rate was not affected. Treatment with eCG increased fertility in Control cows; eCG may be useful in GnRH-based protocols in lactating beef cows.

13 EFFECTS OF PLASMA PROGESTERONE CONCENTRATIONS ON LH RELEASE AND OVULATION IN BEEF CATTLE GIVEN GnRH

2006 ◽  
Vol 18 (2) ◽  
pp. 115
Author(s):  
H. Davis ◽  
M. Colazo ◽  
M. Rutledge ◽  
J. Small ◽  
J. Kastelic ◽  
...  
Keyword(s):  
Animal Health ◽  
Beef Cows ◽  
Dominant Follicle ◽  
Plasma Progesterone ◽  
Lactating Cows ◽  
Significant Difference ◽  
Prostaglandin F ◽  
Pfizer Animal Health ◽  
Lh Release ◽  
To Receive

Two experiments were conducted to determine the effects of plasma progesterone (P4) concentrations on LH release and ovulation in beef heifers and lactating beef cows given gonadotropin-releasing hormone (GnRH). Previously autoclaved, once-used CIDR inserts (Colazo et al. 2004 Anim. Reprod. Sci. 81, 25-34) were used for experimental purposes to induce differential plasma progesterone concentrations. In Experiment 1, postpubertal heifers received 25 mg of dinoprost i.m. (prostaglandin F (PGF); Lutalyse; Pfizer Animal Health, Montreal, Quebec, Canada). On Day 4 (estrus = Day 0), heifers were randomly assigned (10/group) to receive no treatment (control) or 1 or 2 autoclaved once-used CIDR (Pfizer Animal Health) inserts (1CIDR and 2CIDR, respectively). On Day 5, heifers in the 1CIDR group were given PGF twice 12 h apart. On Day 6, all heifers received 100 �g of GnRH i.m. (Cystorelin; Merial Canada, Inc., Victoriaville, Quebec, Canada). Once daily on Days 4 to 9, a blood sample was collected and ultrasonography was performed. On Day 6, heifers in the control (3.0 � 0.4 ng/mL; mean � SD) and 1CIDR groups (3.0 � 0.3 ng/mL) had lower (P < 0.01) plasma progesterone concentrations than those in the 2CIDR group (5.7 � 0.4 ng/mL). However, the diameter of the dominant follicle was larger (P < 0.001) in heifers in the control and 1CIDR groups than in the 2CIDR group (12.1 � 1.0, 11.5 � 0.7, and 10.1 � 0.7 mm, respectively). More (P < 0.01) heifers ovulated in response to GnRH in the control and 1CIDR groups than in the 2CIDR group (10/10, 9/10, and 3/10, respectively). In Experiment 2, ultrasound-guided follicular ablation (FA) was performed (to synchronize ovarian follicular wave emergence) 4 to 6 days after estrus in 20 postpubertal heifers and 20 mature lactating cows. Cattle were randomly and equally assigned to receive an autoclaved, once-used CIDR, either with no further treatment (High-P4) or with two PGF treatments 12 h apart (Low-P4) given after FA. All cattle received 100 �g of GnRH either 6 days after FA or the day after the dominant follicle reached 9 mm in diameter. Ultrasonography was performed daily (from 4 days after FA to ovulation or to 3 days after GnRH treatment). In three cows and three heifers per group, blood samples were collected every 30 min for 12 h after GnRH. The dominant follicle at GnRH treatment was larger in cows than heifers (11.0 � 1.1 vs. 10.3 � 0.9 mm, respectively; P = 0.05) and tended to be smaller in the High-P4 group vs. the Low-P4 group (10.3 � 1.0 vs. 11.0 � 1.0 mm; P = 0.06). Ovulatory response was not different (P = 0.9) between heifers (77.7%) and cows (78.9%), but combined for heifers and cows, was lower in High-P4 vs. Low-P4 cattle (61.1 vs. 94.7; P < 0.01). The GnRH-induced LH surge did not differ (P = 0.23) between cows and heifers, but it was lower and of shorter duration (P < 0.001) in the High-P4 group than in the Low-P4 group. In summary, higher plasma P4 concentrations resulted in decreased LH release and the proportion of cattle ovulating in response to GnRH treatment. There was no significant difference between heifers and cows in LH release or ovulatory response.

20 ADMINISTRATION OF FOLLICLE-STIMULATING HORMONE AT CIDR REMOVAL DOES NOT AFFECT THE PREGNANCY RATE IN A CIDR-BASED, COSYNCH PROTOCOL IN LACTATING BEEF COWS

2008 ◽  
Vol 20 (1) ◽  
pp. 90 ◽  
Author(s):  
J. Small ◽  
F. Dias ◽  
L. Pfeifer ◽  
K. Lightfoot ◽  
M. Colazo ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Pregnancy Rate ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Animal Health ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Condition Score ◽  
Secondary Objective ◽  
Pfizer Animal Health

In previous studies, giving eCG at CIDR removal significantly increased the pregnancy rate after timed-AI in beef cows. However, eCG is not universally available. Therefore, we tested the hypothesis that giving pFSH at CIDR removal might improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows; a secondary objective was to compare pregnancy rates when GnRH v. pLH was used to synchronize wave emergence and ovulation. This work was conducted as two experiments (separate locations). All cows were given a CIDR (containing 1.9 g progesterone; Pfizer Animal Health, Montreal, QC, Canada) on Day 0 (without regard to stage of estrous cycle or cyclicity). On Day 7, CIDRs were removed, all cows were concurrently given 25 mg PGF (Lutalyse; Pfizer Animal Health, Groton, CT, USA), half were given 20 mg pFSH (Folltropin-V; Bioniche Animal Health, Belleville, ON, Canada), and all cows were timed-AI 54 h later (Day 9). In Experiment 1, 240 cows [94 � 10.8 days postpartum; body condition score (BCS: 1 = emaciated, 9 = obese; mean � SD): 5.8 � 0.4] were used; at CIDR insertion and AI, cows were allocated to receive either 100 µg GnRH (n = 160; Cystorelin, Merial Canada Inc., Victoriaville, QC, Canada) or 12.5 mg pLH (n = 80; Lutropin-V, Bioniche Animal Health). In Experiment 2, 109 cows (59.2 � 19.5 days postpartum; BCS: 5.6 � 1.1) were used; all received 100 µg GnRH (Cystorelin) at CIDR insertion and AI. In Experiment 1, three cows that lost their CIDR were excluded; pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, synchronizing treatment, and their interactions) were not different between cows given pFSH v. control cows (64.7 v. 65.2%; P > 0.80), nor between cows given GnRH v. pLH (62.7 v. 69.6%; P = 0.91). However, there was an interaction (P < 0.04) between parity and the synchronizing treatment; in primiparous cows, pregnancy rates were significantly lower in those given GnRH v. pLH (59.3 v. 83.3%). In Experiment 2, pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, and their interaction) were not different between cows given pFSH v. control cows (38.2 v. 42.6%; P > 0.6). In conclusion, our hypothesis was not supported; giving pFSH at CIDR removal did not significantly improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows.

21 DEVELOPMENT OF A TIMED INSEMINATION PROGRAM IN DAIRY HEIFERS AS A PLATFORM TO DETERMINE IF FLUNIXIN MEGLUMINE IMPROVES PREGNANCY RATE AND EMBRYO SURVIVAL

2008 ◽  
Vol 20 (1) ◽  
pp. 90 ◽  
Author(s):  
W. W. Thatcher ◽  
C. A. Risco ◽  
J. Larson ◽  
M. J. Thatcher ◽  
F. Lima ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Animal Health ◽  
Embryo Survival ◽  
Dairy Heifers ◽  
Flunixin Meglumine ◽  
Prostaglandin F ◽  
Pfizer Animal Health ◽  
Prostaglandin H ◽  
Rectal Palpation ◽  
To Receive

The objectives of the present series of experiments were to develop a timed artificial insemination (TAI) program for dairy heifers and to utilize a TAI program to evaluate the effect of flunixin meglumine (Banamine�; Schering-Plough Animal Health Corp., Atlanta, GA, USA), a prostaglandin H synthase (PGHS)-2 inhibitor, on pregnancy rate and embryo survival. In Experiment 1, 247 heifers were assigned randomly to a prostaglandin F (PGF)/gonadotropin-releasing hormone (GnRH) TAI [i.e., 2 injections of Lutalyse� (25 mg, IM; Pfizer Animal Health Inc., Groton, CT, USA) given 14 days apart in the PM; 60 h after the 2nd Lutalyse injection, heifers received a GnRH injection (Cystorelin�; 100 µg, IM; Merial, Duluth, GA, USA) and were TAI] or a 5-day CIDR/Synch TAI [intravaginal insertion of a CIDR� device (Pfizer Animal Health Inc.) and an injection of GnRH in the AM; 5 days later in the AM, the CIDR insert was removed and Lutalyse was injected, followed by a 2nd injection of Lutalyse� 12 h later; heifers were TAI and injected with GnRH at 72 h after CIDR removal]. Blood samples for progesterone analyses were taken 7 days apart prior to initial PGF or CIDR insertion from the respective groups to determine cycling status. The CIDR/Synch TAI heifers tended to have greater Day 32 (53.1, >46.2%) ultrasound pregnancy rate (USPR) and Day 42 (50.8, >43.7%) rectal palpation (RPPR) than PGF/GnRH heifers (P = 0.10); 4/9 non-cycling heifers of the CIDR/Synch TAI group conceived v. 0/3 of the PGF/GnRH TAI group. In Experiment 2, 176 heifers underwent the CIDR/Synch TAI protocol. However, 2 injections of cloprostenol [500 µg AM/PM; Estrumate�, Schering-Plough Animal Health Corp.) were used to regress the CL at CIDR removal. Heifers at initiation of the CIDR/Synch TAI protocol were assigned randomly to receive injections of Banamine (400 mg IM) at Day 15.5 and at Day 16.0 or no injections (control). Banamine treatment failed to alter either Day 32 USPR (59.6% Banamine v. 59.8% control) or Day 46 RPPR (59.6% Banamine v. 58.6% control). Overall, 4/11 non-cycling heifers conceived. In Experiment 3, 147 heifers underwent a UsedCIDR/Synch TAI protocol utilizing cloprostenol as in Experiment 2. A 5-day used CIDR was employed. Heifers at initiation of the UsedCIDR/Synch TAI protocol were assigned randomly to receive injections of Banamine (400 mg IM) at Day 15.5 and at Day 16.0 or no injections (control). Banamine treatment failed to alter either Day 32 USPR (60.5% Banamine v. 62.0% control) or Day 46 RPPR (59.2% Banamine v. 60.6% control). Pooled overall analyses of pregnancy rates for dairy heifers receiving the CIDR/Synch TAI treatments (n = 451), adjusted for experiments, were 58.3% at Day 32 (USPR) and 57.6% at Day 46 (RPPR). In conclusion, Banamine failed to improve pregnancy rate and/or late embryo survival in dairy heifers, and a CIDR/Synch TAI program is very effective for optimizing the pregnancy rate in dairy heifers. This work was supported by the Florida-Georgia Milk Check-off program.

Response of beef heifers and non-suckling beef cows to different oestrous synchronization protocols

2002 ◽  
Vol 74 (3) ◽  
pp. 547-552 ◽  
Author(s):  
D. Cavestany ◽  
N. Negrin ◽  
R. Negrin ◽  
J. F. Groth
Keyword(s):  
Beef Cattle ◽  
Medroxyprogesterone Acetate ◽  
Artificial Insemination ◽  
Experimental Period ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Gnrh Analogue ◽  
Beef Heifers

AbstractThe objective was to evaluate different oestrous synchronization schemes in beef cattle under range conditions. In experiment 1, 202 heifers averaging 26 months of age were assigned randomly to three treatments: (a) GnRH-PG. (no. = 44) day 0 (D0): injection of GnRH; D7: injection of PGF2α; D0 to D25 oestrous detection (OD) and artificial insemination (AI); (b) OD-PG. (no. = 45) D0 to D4; OD + AI; D5: injection of PGF2α; D5 to D25 OD + AI; and (c)Ovsynch. (no. = 113) D0: injection of GnRH; D7: injection of PGF2α; D9: injection of GnRH and 16 h later AI at fixed time. In experiment 2, 318 non-suckling cows were assigned randomly to three treatments: (a) GnRH-PG. (no. = 106) D0: injection of GnRH; D7: injection of PGF2α; D0 to D25 OD + AI; (b) GnRH-MAP-PG. (no. = 106) D0: injection of a GnRH analogue and insertion of an intravaginal sponge impregnated with 250 mg of medroxyprogesterone acetate; D7: injection of PGF2α and sponge withdrawal; D0 to D25 OD + AI; (c) controls. (no. = 106) OD and AI. The experimental period lasted 25 days and, with exception of the Ovsynch treatment, oestrous detection was carried out twice a day (a.m./p.m.) and inseminations performed 12 h later. The pregnancy rates assessed by ultrasonography 30 days after AI were: experiment 1: (a) 30·0%; (b) 28·6% and (c) 62·3% (P < 0·05); experiment 2: (a) 60·2%; (b) 57·8% and (c) 45·5% (P < 0·05). It is concluded that in heifers and non-suckling cows, oestrous synchronization treatments result in higher pregnancy rates. In non-suckling cows, the addition of a progestagen did not improve the response.

scholarly journals 183PREGNANCY RATE FOLLOWING TRANSFER OF IN VITRO- AND IN VIVO-PRODUCED BOVINE EMBRYOS TO LH-TREATED RECIPIENTS

2004 ◽  
Vol 16 (2) ◽  
pp. 213 ◽  
Author(s):  
J. Small ◽  
M. Colazo ◽  
D. Ambrose ◽  
R. Mapletoft ◽  
J. Reeb ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Animal Health ◽  
Beef Cows ◽  
Water Bath ◽  
Bovine Embryos ◽  
Chi Square ◽  
Embryo Survival ◽  
Frozen Embryos

The objective was to evaluate the effect of pLH treatment on pregnancy rates in recipients receiving in vivo- or in vitro-produced bovine embryos. Heifers (n=37) and lactating (n=28) and non-lactating (n=150) beef cows were treated at random stages of the cycle with 100μg GnRH i.m. (Cystorelin, Merial Canada Inc., Victoriaville, Quebec, Canada) on Day −9, 500μg cloprostenol i.m. (PGF; Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada) on Day —2 and GnRH on Day 0 (66h post-PGF; without estrus detection). Cattle were placed at random, by class, into three groups: no further treatment (Control; n=71), or 12.5mg pLH (Lutropin-V, Bioniche Animal Health, Belleville, Ontario, Canada) on Day 5 (n=72) or on Day 7 (n=72) after the second GnRH. On Day 7, cattle with a CL &gt;10mm in diameter (determined ultrasonically) received in vivo-produced, fresh (Simmental) or frozen (Holstein), or in vitro-produced frozen (Holstein) embryos (embryo type balanced among groups). Embryos were cryopreserved in 10% ethylene glycol; in vivo-produced frozen embryos were thawed 5 to 10s in air, 15s in a water-bath at 30°C and then “direct-transferred” nonsurgically. In vitro-produced frozen embryos (donated by IND Lifetech Inc., Delta, British Columbia, Canada) were thawed in a water-bath at 27°C for 10s and placed in ViGro Holding Plus medium (AB Technology, Pullman, WA, USA) at room temperature, evaluated and then transferred nonsurgically. Pregnancy was determined by ultrasonography on Day 35. Data were analyzed with CATMOD, chi-square and GLM procedures (SAS Institute, Cary, NC, USA.). Twenty cattle (9.3%) did not receive embryos; five heifers had cervical problems, and five heifers and 10 cows did not have a CL &gt;10mm. Overall, 7.1% of the recipients had two CL on the day of embryo transfer. There was no effect (P&gt;0.05) of treatment, embryo type (or interaction) or class of recipient on pregnancy rate (overall, 44.1%, 86/195; Table 1). Similarly, mean (±SD) CL diameter and luteal area did not differ (P&gt;0.05) among groups or between pregnant and open recipients (overall, 22.0±3.4mm and 352.0±108.7mm, respectively). However, recipients with a CL diameter ≥18mm tended (P&lt;0.1) to have a higher pregnancy rate (45.8 vs 25.0%). In a subset of 40 recipients examined ultrasonically on Day 12, 50% of those treated on Day 5 and 70% of those treated with pLH on Day 7 had two CL. In summary, overall pregnancy rate in GnRH-synchronized recipients receiving in vitro- or in vivo-produced embryos by nonsurgical transfer was 44.1%. Embryo survival to Day 35 was not affected by type of embryo or treatment with pLH 5 or 7 days after ovulation. Table 1 Pregnancy rate in recipients on Day 35 based on pLH treatment and embryo-type

162 FERTILITY OF BEEF RECIPIENTS FOLLOWING A FIXED-TIME EMBRYO TRANSFER PROTOCOL WHICH INCLUDED FOLLICLE STIMULATING HORMONE DILUTED IN HYALURONAN

2013 ◽  
Vol 25 (1) ◽  
pp. 229
Author(s):  
J. W. Thorne ◽  
C. R. Looney ◽  
J. F. Hasler ◽  
D. K. Hockley ◽  
D. W. Forrest
Keyword(s):  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Transfer Rate ◽  
Animal Health ◽  
Fixed Time ◽  
Control Groups ◽  
Pfizer Animal Health ◽  
And Control ◽  
Estradiol 17Β

This study was performed to test the viability of administering Folltropin-V® (FSH, Bioniche Animal Health) diluted in hyaluronan (MAP-5 50 mg, sodium hyaluronate, Bioniche Animal Health) to beef cows enrolled in a recipient synchronization protocol to evaluate its effect on recipient fertility. All recipients were administered an estradiol 17β (2.5 mg, IM) and progesterone (50 mg, IM) combination injection on Day 0, a CIDR® (progesterone 1.34 g, Pfizer Animal Health, Groton, CT, USA) was inserted for 7 days. Lutalyse® (dinoprost tromethamine, Pfizer Animal Health, 25 mg, IM) was administered at the time of CIDR removal on Day 7, and estradiol 17β (1 mg, IM) was administered on Day 8. On Day 16, the presence of at least one corpus luteum, detected via ultrasound, resulted in the recipient receiving an embryo (both fresh and frozen–thawed embryos were used). Embryos were not transferred into cows that did not show ultrasonic evidence of a CL. Dependent variables for which data were collected included circulating progesterone levels at the time of transfer and CL diameter, area, and circumference; measured in millimeters. The total study (n = 274) consisted of both wet (n = 85) and dry (n = 189) cows and included both Bos indicus (Brahman-influenced) crossbred (n = 93) and Bos taurus (Angus-based) cows (n = 181). The experiment consisted of cows being placed in either the treated or control groups, with treated cows receiving a single 40 mg (1 mL) IM injection of Folltropin-V in hyaluronan on Day 5 and control cows receiving no additional injections. Results are shown in Table 1. Transfer rate, conception rate, and pregnancy rate were tested for significance with chi-square analysis and remaining statistics were analyzed with a t-test: two-sample assuming equal variances. There were no significant differences found between the treated and control groups for transfer rate, conception rate, or pregnancy rate. Corpus luteum diameter was shown to be larger in control cows (P < 0.05); however, CL area and circumference did not differ significantly. Folltropin-V given with hyaluronan at a 40-mg dose on Day 5 did not improve fertility, induce a larger CL, or increase circulating progesterone levels in synchronized beef recipients as hypothesized. Further work is needed with Folltropin-V in hyaluronan to determine if an alternative dose or timing of administration would be more appropriate for improving fertility in recipients. Table 1.Fertility data in beef recipients following synchronization for fixed-time embryo transfer with a protocol that included (Treated) or did not include (Control) FSH in hyaluronan

7 INFLUENCE OF ESTRUS EXPRESSION AND TREATMENT WITH GnRH ON PREGNANCY RATES IN BEEF CATTLE SYNCHRONIZED WITH PROGESTERONE DEVICES AND ESTRADIOL AND INSEMINATED AT A FIXED-TIME

2017 ◽  
Vol 29 (1) ◽  
pp. 111 ◽  
Author(s):  
G. A. Bó ◽  
A. Cedeño ◽  
A. Tribulo ◽  
S. Andrada ◽  
R. Tribulo ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Beef Cattle ◽  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Device Removal ◽  
Oestradiol Benzoate ◽  
Condition Score ◽  
To Receive

We have previously shown that expression of oestrus significantly influences the time of ovulation and pregnancy rates to timed-AI (P/TAI) in beef cattle synchronized with progesterone devices and oestradiol (Bó et al. 2016 Theriogenology 86, 388–396). Furthermore, delaying TAI from 48 h to 54–58 h after device removal improved P/TAI of those animals not showing oestrus by 48 h. The objective of the present study was to determine whether the administration of GnRH to those animals not showing oestrus by 48 h after device removal had an impact on P/TAI. Non-lactating and suckled beef cows and heifers (Bonsmara, Brangus, and Braford; n = 868), with a corpus luteum (CL) or a follicle ≥8 mm in diameter detected by ultrasonography (Mindray DP 30 Vet, 7.5 MHz, China) and body condition score 2 to 4 (1 to 5 scale) were synchronized in 3 replicates. On Day 0, animals received a progesterone device (DIB 0.5 g, Zoetis, Argentina) and 2 mg of oestradiol benzoate (Von Franken, Argentina). On Day 8, DIB were removed and cows received 0.150 mg of D+cloprostenol (Río de Janeiro, Argentina) plus 0.5 mg oestradiol cypionate (Cipiosyn, Zoetis). In addition, all cows were tail-painted on the sacrococcygeal area (CeloTest, Biotay, Argentina) at DIB removal and were observed to determine the expression of oestrus, according to the percentage of paint loss (PL) 48 h later. The animals that showed oestrus (PL > 30%) were recorded and TAI at that time while those with PL ≤ 30% (not in oestrus) were randomly allocated to receive 100 μg of gonadorelin (GnRH; Gonasyn, Zoetis) or no treatment and TAI between 54 to 58 h after DIB removal. Pregnancy was diagnosed by ultrasonography at 45 days after TAI, and data were analysed by logistic regression. There were no significant differences among replicates, inseminators, semen source or animal class (dry cows, suckled cows or heifers; P > 0.11). However, animals showing oestrus by 48 h after DIB removal had higher P/TAI (371/666; 55.7; P < 0.04) than those that did not show oestrus (96/202; 47.5%). Within animals not showing oestrus at 48 h, those that were in oestrus by the TAI at 54 to 58 h had higher P/TAI (71/124, 57.3%; P < 0.01) than those that did not show oestrus within that period (27/78; 34.6%). In addition, P/TAI was higher (P < 0.01) in animals that received GnRH (66/113; 58.4%) than in those that did not receive GnRH (30/89; 33.7%). In conclusion, the expression of oestrus significantly affected P/TAI in beef cattle synchronized with progesterone devices and oestradiol. Furthermore, treatment of animals not showing oestrus by 48 h after DIB removal with GnRH resulted in improved P/TAI performed 6 to 10 h later.

Effect of 1 or 2 norgestomet implants inserted from days 15 to 25 after oestrus on follicular development in beef cows

1996 ◽  
Vol 1996 ◽  
pp. 133-133
Author(s):  
D.A. Adikpe ◽  
M.J. Bryant
Keyword(s):  
Pregnancy Rate ◽  
False Positive ◽  
Luteal Phase ◽  
Follicular Development ◽  
Beef Cows ◽  
Beef Heifers ◽  
Follicular Wave ◽  
Ovulatory Follicle

Controlling the timing of ovulation in cows that fail to conceive after insemination would provide a further opportunity for scheduled rebreeding in a group of cows to save time and optimise results. The ear implant Crestar containing the synthetic progestagen norgestomet provides a means of achieving this control (Sinclair et al., 1992; Lowman et al., 1994). Removing the implant on day 25 after oestrus results in less false positive pregnancy diagnoses than removal on day 21 with the implant in place for nine/ten days. However, treatment of beef heifers with a norgestomet implant towards the end of luteal phase to control oestrus and ovulation is associated with development of a persistent ovulatory follicle and reduced pregnancy rate (Mihm et al., 1994). The objective of this study was to determine the effects of treating beef cows with one or two norgestomet implants on the development of the dominant ovulatory follicle of the second follicular wave.

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