scholarly journals Randomised clinical trial evaluating the effect of different timing and number of fixed timed artificial inseminations, following a seven-day progesterone-based protocol, on pregnancy outcomes in UK dairy heifers

2017 ◽  
Vol 181 (22) ◽  
pp. 595-599 ◽  
Author(s):  
John Paul Walsh ◽  
Amy Coates ◽  
Fabio Lima ◽  
Rob Smith ◽  
Georgios Oikonomou

The objective of this study was to determine the effect on pregnancy outcome of either inseminating heifers twice (at 48 and 72 hours after withdrawal of a controlled internal drug release insert (CIDR) containing progesterone) or once (56 hours after CIDR withdrawal) following a seven-day CIDR synchronisation protocol. Dairy heifers (n=267) from five farms, with an age range of 388–736 days, were randomly assigned to one of two treatment groups (group A heifers were inseminated twice; group B heifers were inseminated once). Both groups received a CIDR on day (D) 0 and an intramuscular injection of d-cloprostenol on D6; the CIDR was withdrawn on D7. Measurements of withers height, body condition score and hearth girth (used to estimate weight) were taken on D0. The diameter of the largest follicles and corpora lutea was recorded on both D0 and D6. Data were analysed with the use of multivariable logistic regression modelling. Treatment group and farm were not statistically significantly associated with pregnancy per treatment (P/T). Age and dominant follicle size on D6 were significantly associated with P/T. Heifers with the largest dominant follicle sizes (16–22 mm) were 5.54 times less likely to be pregnant than those heifers with the smallest dominant follicles (8–10 mm) on D6. It was shown that the cost associated with inseminating heifers twice after a seven-day CIDR synchronisation protocol is not justified.

1991 ◽  
Vol 52 (1) ◽  
pp. 157-163 ◽  
Author(s):  
R. G. Gunn ◽  
T. J. Maxwell ◽  
D. A. Sim ◽  
J. R. Jones ◽  
M. E. James

ABSTRACTThe effects of high-low (HL) and low-high (LH) patterns of nutrition during the 5 weeks prior to a synchronized mating were studied on the reproductive performance of 115 Welsh Mountain and 114 Brecknock Cheviot ewes in a range of body condition at the start of treatment. For 2 months prior to treatment imposition, ewes were grazed in a systematic way at different stocking rates on different sward heights to obtain a range of body condition scores. Target score groupings were 2·00 to 2·25, 2·50 to 2·75 and 3·00 to 3·25 and although scores of 1·50 to 3·25 were obtained, most lay in the 2·00 to 2·75 range. Two treatment groups, balanced for live weight and body condition score, received high and low levels of nutrition for 16 days from mid October, achieved, respectively, by a low stocking rate on a sward with a high surface height plus ad libitum concentrate and a high stocking rate on a sward with a low surface height plus 200 g hay per head per day. Treatments were then reversed for the 17 days prior to mating. Live-weight and body condition-score changes were recorded and reproductive performance at first mating was measured from counts of corpora lutea and viable embryos at slaughter either at return to service or at 4 weeks after first mating. There were no differences due to nutritional pattern in live weight or body condition score at mating. The LH treatment significantly increased the rates of ovulation, conception, multiple ova survival and potential lambing per ewe pregnant and per ewe mated in the Welsh Mountain breed but significantly increased only the rates of ovulation and potential lambing per ewe pregnant in the Brecknock Cheviot breed compared with the HL treatment. The relatively poorer response in the latter breed was partially due to a lower ovulation rate potential coupled with non-significantly lower rates of conception and survival of single-shed ova associated with the LH treatment. Much of this relatively poorer reproductive performance in the Brecknock Cheviot breed was in ewes with body condition scores 3= 2·75. Reproductive performance increased with increasing body condition at the start of treatment over the range of scores =≤ 2·25 to 2·50 in both breeds and, while continuing to improve in scores above 2·50 in the Welsh Mountain breed, in the Brecknock Cheviot breed it started to decline. Ewes with a body condition score of 2·50 in both breeds showed the greatest response in potential lambing rate to the LH treatment.


2021 ◽  
Vol 8 (2) ◽  
pp. 30
Author(s):  
Luis Emilio Fazzio ◽  
Santiago José Raggio ◽  
Juan Facundo Romero ◽  
Juver Membrebe ◽  
Antonio Humberto Hamad Minervino

A safety study on ketoprofen 10% was carried out on pigs using a different dosing and treatment scheme. Forty healthy crossbreed pigs with similar age, weight, and body condition score were distributed into five treatment groups. The pigs were intramuscularly injected once with different doses of ketoprofen: 3 mg/kg (group 1X), 6 mg/kg (group 2X), 9 mg/kg (group 3X). In addition, the 3 mg/kg dosis was administered on three consecutive days (group 1X ext.). Intramuscular injections of saline solution were used in control group (CTL). The pigs were clinically examined throughout the trial and blood samples were taken for hematological and biochemical evaluation on days −4 (before treatment), +3, +7, and +14 (the end of the trial). Any unusual behaviour or clinical signs were reported as potential toxic effects of ketoprofen. Serum measurements showed that none of the ketoprofen doses produced changes in renal or hepatic biochemical parameters, liver enzymes, or total bilirubin. Likewise, hematological assessment indicated no altered parameters or hematocrit percentage in the study groups. These results demonstrate that ketoprofen has no adverse effects in pigs when the doses and scheme evaluated in this study are applied.


1979 ◽  
Vol 29 (2) ◽  
pp. 277-282 ◽  
Author(s):  
R. G. Gunn ◽  
J. M. Doney ◽  
W. F. Smith

ABSTRACTOver 2 years, 104 Greyface ewes were mated at a synchronized oestrus either in early October or early November. From late September until slaughter at return to service or between 4 and 7 weeks after mating, ewes were fed to maintain their body condition score as previously adjusted by differential group feeding on grass. Ovulation rate and potential lambing rate were derived from counts of corpora lutea and viable embryos at slaughter. Both rates were higher in the early-mated ewes in comparable body condition. Stress factors were implicated as contributing to the decline in ovulation rate with time, while ewes which failed to hold to first mating were largely responsible for the decline in potential lambing rate.


1985 ◽  
Vol 41 (2) ◽  
pp. 167-175 ◽  
Author(s):  
M. J. Ducker ◽  
Rosemary A. Haggett ◽  
W. J. Fisher ◽  
S. V. Morant

ABSTRACTData from a large controlled experiment to investigate the effect of level of nutrition on reproductive performance were used to assess the value of production and blood measures as indicators of energy status in lactating dairy heifers. Live-weight change showed the strongest and most consistent relationship to mean energy balance (the difference between metabolizable energy intake and that used for milk production and maintenance) (P < 0·01 to P < 0·001). Body-condition score at a particular time was more closely related to mean energy balance in the preceding 4-week period (P < 0·05) than current energy balance. There was also a lag in the relationship between energy balance and live-weight change and mean body-condition score. Ultrasonic back fat measurements were significantly correlated with both loin and tailhead body-condition score (P < 0·001) but were more strongly related to mean energy balance in the preceding period (P < 0·05 to P < 0·001) than the body-condition scores.Blood samples were taken from all heifers 2 weeks before calving and 1, 5, 9, 13 and 18 weeks after calving and were analysed for 13 constituents. Concentrations of blood metabolites did not show consistently strong correlations with mean energy balance. The only blood metabolite to be measurably affected by the nutritional treatments applied in lactation was β-hydroxybutyrate.At best, combinations of production measures and blood metabolites were only able to predict the mean daily energy balance with a 95% confidence interval of ±20 MJ for an individual animal although this confidence interval was reduced to ±3 MJ for 100 animals.


2010 ◽  
Vol 22 (1) ◽  
pp. 177 ◽  
Author(s):  
M. Ramos ◽  
L. Cutaia ◽  
P. Chesta ◽  
G. A. Bó

Two experiments were designed to evaluate the effect of the timing of fixed-time AI (FTAI) in relation to the removal of an intravaginal progesterone-releasing device (1 g of progesterone, DIB, Syntex SA, Buenos Aires, Argentina) on pregnancy rates in Bos indicus × Bos taurus cross-bred heifers. In experiment 1, 285 Bonsmara × zebu cross-bred heifers, between 18 and 24 months of age and with a body condition score (BCS) between 3.0 and 3.5 (1-5 scale) were used. On the day of initiation of treatment (Day 0), the heifers’ ovaries were palpated (92% of them had a CL) and they received a new DIB plus 2 mg of estradiol benzoate (EB; Syntex SA) and 250 μg of cloprostenol (Ciclase DL, Syntex SA). On Day 8, DIB devices were removed and all heifers received 250 μg of Ciclase plus 0.5 mg of estradiol cypionate (ECP; Cipiosyn, Syntex SA). At that time the heifers were randomly divided to receive FTAI between 48 to 49 h, 53 to 54 h, or 58 to 59 h after DIB removal. The heifers underwent FTAI with semen from 4 bulls by 2 inseminators. In experiment 2, 260 heifers from the same group as those used in experiment 1 (87% with a CL) were treated exactly as those in experiment 1, except that previously used DIB was inserted on Day 0. Pregnancy diagnosis was performed 30 days post-fixed-time AI by ultrasonography. The data were analyzed by logistic regression, taking into account the effect of time of FTAI, semen, and inseminator on pregnancy rates. In experiment 1, pregnancy rates were lower (P = 0.04) in the heifers undergoing FTAI between 48 and 49 h after DIB removal (46/95, 48.4%) than those undergoing FTAI 53 to 54 h (61/99, 61.6%) or 58 to 60 h (57/91, 62.6%) after DIB removal. However, no differences in pregnancy rates were found (P = 0.72) in experiment 2 between the 3 treatment groups, with 39/91 (42.9%) for the 48 to 49 h group, 45/89 (50.6%) for the 53 to 54 h group, and 35/89 (43.8%) for the 58 to 59 h group. There was no effect of the semen or inseminator (P > 0.2) in either experiment. We conclude that when Bos indicus × Bos taurus beef heifers are synchronized with new DIB devices and ECP, higher pregnancy rates are obtained in heifers undergoing FTAI late (between 53 to 60 h after DIB removal) than in those undergoing FTAI early (48 to 49 h after DIB removal). However, time of insemination does not apparently affect pregnancy rates when Bos indicus × Bos taurus beef heifers are synchronized with previously used DIB devices and ECP.


2021 ◽  
Vol 33 (2) ◽  
pp. 181
Author(s):  
C. Brochado ◽  
B. J. Duran ◽  
J. C. L. Motta ◽  
J. D. Kieffer ◽  
A. Pinczak ◽  
...  

The objective of the present study was to evaluate the effect of length of the FSH superstimulatory treatment on ovarian response and embryo production in sheep. Poll Dorset ewes (n=63) 3.2±0.2 years old weighing 58.5±1.5kg and with a body condition score of 2.7±0.1 (0=emaciated; 5=obese) were used during the transition from the breeding to the non-breeding season. All ewes received an ovarian superstimulatory treatment during the first follicular wave (Day 0 protocol). On Day −9 all ewes received a 0.3-g progesterone intravaginal device (CIDR, Zoetis) for 6 days. On Day −3, the CIDR was removed and all ewes were administered 125μg of cloprostenol sodium intramuscularly (IM) (PGF, estroPLAN, Parnell) and 200IU of equine chorionic gonadotrophin (eCG)+100IU of human chorionic gonadotrophin (hCG) IM (P.G. 600, Merck). Thirty-six hours after CIDR removal (Day −1.5) ewes were administered 100μg of gonadorelin acetate IM (gonadotrophin-releasing hormone, GnRH; Gonabreed, Parnell). Superstimulatory treatments were initiated on Day 0 (84 h after CIDR removal) with a total of 240mg of NIH-FSH-P1 (12 mL, Folltropin, Vetoquinol), and a new CIDR was used from the first to the last FSH dose (6-dose=3 days; 8-dose=4 days). Ewes were randomised to receive the total dose of FSH distributed in eight decreasing doses (8-dose group, n=33) or six decreasing doses (6-dose group, n=30) twice daily 12h apart. Two doses of PGF were administered with the last two doses of FSH, and GnRH was administered 12h after the last FSH administration. Intrauterine AI with fresh semen was performed by laparoscopy 16h after GnRH administration. Ovarian response was determined by laparoscopy 6 days after AI and ova/embryos were collected surgically in ewes with &gt;2 corpora lutea (CL). Data were analysed using generalized linear mixed models (SAS 9.4; SAS Institute Inc.) and presented as mean±s.e.m. in Table 1. The percentage of responding donors (&gt;2 CL) was 93.3% (28/30) and 78.8% (26/33; P=0.5) for the 6-dose and 8-dose groups, respectively. The number of CL tended (P=0.06) to be lesser in ewes in the 6-dose than the 8-dose group. However, no differences (P&gt;0.10) were found in total ova/embryo, fertilized ova, transferable embryos, or freezable embryos. In conclusion, despite a tendency for a greater ovarian response in ewes treated with 8 doses of FSH, embryo yield did not appear to differ after either 6 or 8 doses of FSH administered during the first follicular wave in sheep. Table 1. Ovulatory response and embryo production in responding ewes (&gt;2 corpora lutea) superstimulated with either 6 or 8 doses of FSH during the first follicular wave Outcome Treatment P-value 6-dose 8-dose Number of ewes 28 26 Corpora lutea (n) 14.2±1.7 20.3±2.8 0.06 Total ova/embryos (n) 9.0±1.3 10.9±1.8 0.38 Fertilized ova (n) 8.1±1.4 10.2±1.9 0.34 Fertilized ova (% per ewe) 89.0±5.0 81.7±7.0 0.40 Degenerate embryos 1.3±0.4 2.0±0.8 0.89 Transferable embryos (Grade 1–3) 6.8±1.2 8.2±1.8 0.52 Transferable embryos (% per ewe) 85.7±4.4 75.4±8.4 0.46 Freezable embryos (Grade 1–2) 6.6±1.1 8.2±1.8 0.43 Freezable embryos (% per ewe) 80.5±5.6 75.4±8.4 0.61


Animals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3509
Author(s):  
Kangmin Seo ◽  
Hyun-Woo Cho ◽  
Julan Chun ◽  
Junghwan Jeon ◽  
Chanho Kim ◽  
...  

The aim of this study was to evaluate the suitability of fermented oat (FO) and black soldier fly larva (BSFL) as food ingredients for dogs. A total of 20 spayed female dogs were divided into four treatment groups, with 5 dogs per group. The four treatment groups consisted of a control group, a diet with 10% FO, one with 5% BSFL, and one with 10% FO and 5% BSFL, and each experimental food was fed for 12 weeks. The feeding of FO and/or BSFL did not affect the daily food intake, body weight, body condition score, fecal score, or skin condition of the dogs. In all the experimental groups, no significant differences in serum IgG, IL-10, or TNF-α levels were observed upon the feeding of FO and/or BSFL. Some hematological (white blood cell and basophils) and serum biochemical parameters (phosphorous, globulin, and alkaline phosphatase) showed significant differences with FO and/or BSFL feeding compared to the control group, but they were within the normal reference range. No adverse clinical signs related to these parameters being affected by FO and BSFL were observed. The feeding of BSFL for 12 weeks reduced the serum cholesterol level (p < 0.05) at the end of the experiment. Our findings suggest the suitability of FO and BSFL as food materials for dogs.


2014 ◽  
Vol 26 (1) ◽  
pp. 118 ◽  
Author(s):  
M. Re ◽  
J. J. de la Mata ◽  
G. A. Bo

Several studies, performed mainly in North America, have shown that the 5-day co-synch timed-AI (TAI) protocol results in similar or higher pregnancy rates than conventional 7-day co-synch protocols in beef cows and beef and dairy heifers. It is hypothesised that the 5-day co-synch protocol reduces the incidence of persistent follicles and provides for a longer proestrus, with increasing oestradiol concentrations due to continuous gonadotropin support for the dominant follicle (Bridges et al. 2008 Theriogenology 69, 843–851). Similar findings have been reported recently following the use of a shortened oestradiol-based protocol that also provides for a longer proestrus (named J-synch; de la Matta and Bo 2012 Taurus 55, 17–23). A study was designed to compare these 2 treatment protocols for synchronization of ovulation that allow for a prolonged proestrus with the conventional oestradiol-based protocol currently used for TAI in South America for heifers. Cycling Holstein heifers that were, on average, 17 months of age, weighting 350 to 380 kg, and with a body condition score of 2.5 to 3.5 (scale of 1 to 5), were randomly allocated to 1 of 3 treatment groups. Heifers in the 7-day estradiol benzoate (EB) group received a progesterone device (DIB 1 g of progesterone; Syntex SA, Buenos Aires, Argentina) and 2 mg EB (oestradiol benzoate, Syntex SA) on Day 0, 500 μg of cloprostenol (prostaglandin F2α; Sincronil, Proagro SA, Argentina) and DIB removal on Day 7, 1 mg of EB on Day 8, and TAI 30 h later (54 h after DIB removal). Heifers in the J-synch group received a DIB and 2 mg of EB on Day 0, PGF and DIB removal on Day 6, and 10 μg of buserelin acetate [gonadotropin-releasing hormone (GnRH); Receptal, Intervet, Millsboro, MD, USA] and TAI on Day 8 (72 h later). Heifers in the 5-day co-synch group received a DIB and GnRH on Day 0, DIB removal and prostaglandin F2α (twice, 12 h apart) on Day 5, and GnRH along with TAI on Day 8 (72 h later). Treatments were coordinated so that DIB were removed in all groups at the same time to decrease a possible time effect of follicle parameters and pregnancy rates. Two experiments were conducted; the first evaluated follicular dynamics and ovulation rates by twice daily ultrasonography (Honda 101 V, 5.0 MHz) in 20 heifers per group and the second determined pregnancy rates to TAI in 172 heifers. The mean (± standard error of the mean) interval from DIB removal to ovulation was shorter in the 7-day EB group (82.7 ± 3.1 h) than in the J-synch (103.8 ± 3.3 h) and 5-day co-synch (96.8 ± 3.3 h) groups (P = 0.01). However, the mean diameter of the dominant preovulatory follicle was smaller (P = 0.01) in the 7-day EB (12.8 ± 0.5 mm) and the J-synch (13.1 ± 0.6 mm) groups than in the 5-day co-synch group (14.9 ± 0.6 mm). Although pregnancy rates in the second experiment were numerically lower in the 7-day EB group (31/58; 53.4%) and 5-day co-synch group (30/55; 54.5%) than in the J-synch group (37/59; 62.7%), differences were not significant (P > 0.3). Preliminary results indicate that the 3 protocols evaluated result in comparable pregnancy rates to TAI in dairy heifers.


2010 ◽  
Vol 22 (1) ◽  
pp. 366
Author(s):  
B. D. M. Silva ◽  
T. A. S. N. Silva ◽  
L. Dalcin ◽  
C. M. Lucci ◽  
J. P. Neves

Superovulation in ewes has been a source of many studies aimed at obtaining high superovulatory response and number of viable embryos recovered. In a protocol called Day 0, superovulatory treatment was initiated at the time of wave emergence in the absence of a dominant follicle (Menchaca A et al. 2002 Theriogenology 58, 1713-1721). The aim of this study was to compare ovarian response and number of embryos recovered after treatment between ewes treated with a Day 0 protocol and those treated with a traditional protocol. Santa InÊs ewes (n= 18) between 2 and 5 years old were randomly distributed into 2 superovulation treatment groups: traditional protocol and Day 0 protocol. Each treatment was repeated twice in a crossover model. The traditional protocol consisted of the intravaginal insertion of a sponge containing 60 mg of medroxiprogesterone acetate (MAP; Progespon®, Tecnopec, São Paulo, Brazil) for 14 days, which was replaced on Day 7, followed by 150 μg of cloprostenol (Prolise®, Tecnopec) i.m. On Day 12, FSH (Folltropin®-V, Bioniche, Belleville, Ontario, Canada) treatment was initiated using a total dose of 200 mg, given in twice-daily i.m. injections that decreased in dose over 4 days. A dose of 200 IU of eCG (Novormon®, Syntex, Buenos Aires, Argentina) i.m. was given at the time of sponge withdrawal. The AI was done by laparoscopy at 48 and 55 h after sponge withdrawal using fresh semen. The Day 0 protocol consisted of a previous 9-day synchronization treatment with a sponge containing 60 mg of MAP, followed by 150 μ of cloprostenol i.m. and 200 IU of eCG i.m. given on Day 7. A dose of 0.05 mg of GnRH (lecirelin; Gestran Plus®, Tecnopec) i.m. was given 16 h after sponge withdrawal. In a preliminary study, 38 ewes ovulated 42 ± 52 h after sponge withdrawal. Therefore, 48 h after sponge removal was considered as Day 0 and FSH treatment was initiated at that time, with a total dose of 200 mg of Folltropin®-V, given in 6 twice-daily decreasing doses. Two doses of cloprostenol (150 μg) were given i.m. concurrent with the fifth and sixth FSH treatments. Gonadotropin-releasing hormone (0.05 mg of lecirelin i.m.) was given 12 h after the last FSH treatment. Artificial insemination with fresh semen was done by laparoscopy 16 and 26 h after GnRH treatment. Five days after AI, embryos were recovered surgically. Results were evaluated by the parametric t-test. The number of corpora lutea and ova/embryos recovered did not differ (P > 0.05) between the traditional (9.8 ± 5.3; 4.5 ± 4.6) and Day 0 (10.0 ± 6.0; 3.5 ± 4.3) protocols. Similarly, no difference in the number of viable embryos was observed between treatments (1.6 ± 2.0 and 1.7 ± 2.4 for the traditional and Day 0 treatments, respectively). Within viable embryos, the traditional protocol (0.4 ± 1.0) resulted in ahigher (P < 0.05) number of morulae than that of the Day 0 protocol (0.1 ± 0.3). The ewes that had no superovulatory response did not differ (P > 0.05) between the traditional (11.11%) and Day 0 (5.56%) protocols. In summary, there was no difference in the parameters evaluated between both protocols. Financial support: FAPDF, CNPq, Tecnopec.


2017 ◽  
Vol 29 (1) ◽  
pp. 113 ◽  
Author(s):  
E. Pradebon da Silva ◽  
A. B. Machado ◽  
L. S. Gambin ◽  
A. V. Gonsioroski ◽  
M. da Silva ◽  
...  

The aim of this study was to evaluate the effect of presence of corpus luteum (CL) at the onset of timed AI (TAI) protocol, size of ovulatory follicle and oestrus expression on pregnancy rate using E2 cypionate (EC) or GnRH as ovulation inductor in Angus heifers. On day 0, heifers [n = 414; 317 ± 23 kg; 3.08 ± 0.21 body condition score (1 to 5 scale) and 22–24 months of age] received a 1-g progesterone intravaginal device (Primer®, Agener União, Brazil) and 2 mg of oestradiol benzoate, IM, (RIC-BE®, Agener União, Brazil). On day 8, the device was removed, were administered 500 μg of sodium cloprostenol, IM, (Estron®, Agener União, Brazil) and heifers were divided in 2 groups: EC [n = 213; 0.5mg EC, IM, (SincroCP®, Ouro Fino, Brazil) on day 8] and GnRH [n = 201; 25 μg of Licerelin, IM, (GestranPlus®, Agener União, Brazil) at TAI] TAI was performed 50 h after device removal. Heifers were tail painted (Tell Tail®, GEA, New Zealand) to control oestrus expression from device removal to TAI. Heifers were scanned (7.5-MHz linear transducer MediSono® P3V, USA) to determine presence of CL (Day 0), ovulatory follicle diameter (OFD; Day 10) and ovulation (Day 11). Pregnancy was diagnosed 30 days after TAI. Oestrus expression was confirmed when marking ink was removed on day 10. Data were analysed using logistic regression and ANOVA. Oestrus expression was higher (P < 0.05) in EC (93.90%, 200/213) compared to GnRH group (67.66%, 136/201). The OFD differed (P < 0.05) according to presence of CL on Day 0 (10.3 mm) or not (9.6 mm), but was similar in treatment groups. Ovulation rate did not differ in EC (85%, 17/20) and GnRH (95%, 19/20) groups. Pregnancy rates were similar (P > 0.05) between EC (52.58%, 112/213) and GnRH (59.20%, 119/201) groups; however, in heifers that expressed oestrus, rates were higher (P < 0.05) (EC = 56%, 112/200; GnRH = 71.3%, 97/136) than in those did not show (EC = 0%, 0/13; GnRH = 33.8%, 22/65). Presence of CL at onset of TAI protocol was associated with higher pregnancy (P < 0.05) in GnRH group (68%, 68/100) compared with EC (54.46%, 61/112) group, but in heifers without CL, pregnancy were similar for GnRH (50.5%, 51/101) and EC (50.5%, 51/101) groups. Heifers were also classified in 3 groups according OFD: small (≤9.5 mm), medium (9.6–11.5 mm), and large (≥11.6 mm) to verify its effect on oestrus expression and pregnancy. Medium and large OFD were implicated in higher (P < 0.05) oestrus expression [(EC = 100%, 51/51; 96.97%, 32/33) and (GnRH = 83.02%, 44/53; 97.44%, 38/39)] than small OFD [(EC = 85%, 51/60) and (GnRH = 23.8%, 15/63)]. Pregnancy was lower (P < 0.05) in small OFD groups (EC = 28.3%, 17/60; GnRH = 25.4%, 16/63). In medium and large OFD, pregnancy was similar in EC (72.55%, 37/51; 54.55%, 18/33) groups, but differed (P < 0.05) between GnRH large (82.05%, 32/39) and medium (62.26%, 33/53). Higher pregnancy was achieved in heifers with CL in the beginning of TAI protocol treated with GnRH. Size of ovulatory follicle was associated with higher oestrus behaviour and pregnancy rate in EC and GnRH treatments.


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