12 Ovulation Timing Following an Aromatase Inhibitor-Based Synchronization Protocol in Beef Heifers and Cows

2018 ◽  
Vol 30 (1) ◽  
pp. 145
Author(s):  
E. M. Zwiefelhofer ◽  
W. Lillico ◽  
G. P. Adams
Keyword(s):  
Aromatase Inhibitor ◽  
Repeated Measures ◽  
Prostaglandin F2α ◽  
Maximum Diameter ◽  
Beef Heifers ◽  
Lactating Cows ◽  
Follicle Diameter ◽  
Ovulatory Follicle ◽  
Status Interaction ◽  
Synchronization Protocol

The study was conducted to determine the effects of parity/lactation and the timing of gonadotropin-releasing hormone (GnRH) treatment on the efficacy of a non-steroidal aromatase inhibitor-based synchronization protocol in cattle. Results from previous studies confirmed drug-release from a new letrozole-impregnated intravaginal silicone device, which was used in the present study. Hereford-cross cows with suckling calves (41 to 65 days postpartum; n = 30) and sexually mature heifers (n = 30), at random stages of the oestrous cycle, were given a letrozole intravaginal device for 4 days followed by a luteolytic dose of prostaglandin F2α (PGF2α). Following PGF2α treatment, animals were assigned randomly to 3 groups and given GnRH (100 μg of gonadorelin) intramuscularly at 48 or 60 h, or no GnRH (n = 10 cows and 10 heifers per group). Ovaries were examined by transrectal ultrasonography every 8 h starting at the time of PGF2α treatment to record follicle diameter and ovulation. After ovulation, ultrasonography was done every 24 h until Day 10 (Day 0 = ovulation) to assess the corpus luteum (CL) diameter profile. The timing of ovulation, diameter of the preovulatory follicle, synchrony of ovulation, and Day-7 CL diameter were compared using two-way ANOVA, and CL diameter profiles were compared by two-way ANOVA for repeated measures. There was no treatment × parity/lactation status interaction for any endpoint. The ovulation rate within 96 h of PGF2α treatment was not different between heifers and cows (24/30 v. 27/30; P = 0.14) or treatment group (18/20, 18/20, and 15/20 in the 48 h, 60 h, and no GnRH groups, respectively; P = 0.18). The interval from PGF2α treatment to ovulation was not influenced by parity/lactation (83.1 ± 2.4 h) but was shortest in the GnRH 48 h group (mean ± SEM; 74.2 ± 2.7 h, 85.6 ± 4.8 and 89.2 ± 4.1, respectively; P < 0.05). Similarly, the variation in the interval to ovulation (mean ± s.e.M of residuals) was not influenced by parity/lactation (16.0 ± 2.0 h), but was lower in the GnRH groups than the no-GnRH group (P < 0.01), and tended to be lower (P = 0.1) in the GnRH 48-h v. 60-h group (10.0 ± 2.8, 14.2 ± 3.5, and 24.1 ± 3.1 h, respectively). The maximum diameter of the ovulatory follicle was larger for cows than heifers (17.0 ± 0.4 v. 15.1 ± 0.5; P < 0.01), and was smaller in the GnRH groups than the no-GnRH group (15.3 ± 0.3, 15.4 ± 0.7 and 17.3 ± 0.5 mm, respectively; P < 0.01). The diameter of the CL on Day 7 was larger for cows than heifers (22.3 ± 0.8 v. 20.2 ± 0.6 mm; P < 0.05) and was influenced by treatment (21.9 ± 0.5, 19.5 ± 0.7, 22.3 ± 1.1 mm, respectively; P = 0.05). A tendency for a treatment effect on CL diameter profile (P = 0.1) was attributed to a smaller profile in the GnRH 60-h group. In conclusion, GnRH treatment 48 h after PGF2α treatment increased synchrony of ovulation without adverse effects on ovulating follicle diameter or resulting CL growth, and may be incorporated into a novel steroid-free oestrous synchronization protocol for use in beef heifers and lactating cows. Research was supported by the Alberta Livestock and Meat Agency and Vencofarma, Brazil.

scholarly journals Evaluation of forage soybean, with and without pearl millet, as an alternative for beef replacement heifers1

2017 ◽  
Vol 1 (2) ◽  
pp. 179-185
Author(s):  
E. G. Taylor ◽  
P. J. Gunn ◽  
L. A. Horstman ◽  
R. L. Atkinson ◽  
K. Herron ◽  
...  
Keyword(s):  
Pearl Millet ◽  
Body Condition Score ◽  
Control Diet ◽  
Latin Square ◽  
Reproductive Function ◽  
Pregnancy Rates ◽  
Beef Heifers ◽  
Estrous Synchronization ◽  
Follicle Diameter ◽  
Ovulatory Follicle

Abstract Apparent ruminal digestibility of forage soybean-based silages, with and without pearl millet, was determined along with evaluation of silages on heifer performance and reproductive function. Fermenters were utilized in a Latin square design and randomly assigned to 1 of the following treatments: 1) control diet of alfalfa haylage (CON), 2) soybean silage (SB) or 3) soybean and pearl millet silage (SB×PM). All diets were formulated to meet or exceed nutrient requirements of replacement beef heifers targeted to gain 0.79 kg/d. These same diets were fed to 90 Angus-Simmental beef replacement heifers [body weight (BW) = 366 kg; body condition score (BCS) = 5.53; age = 377 ± 11 d] 65 d prior to timed artificial insemination (TAI). Heifers were randomly allotted by breed, BCS and BW to 1 of the 3 treatments, with 3 reps/treatment. Diets were terminated 21 d post-TAI and heifers were commingled and placed on a common diet. Pubertal status was determined by progesterone concentrations of 2 blood samples taken 10 d apart prior to both trial initiation as well as initiation of estrous synchronization. Ovulatory follicle diameter was determined at time of breeding by ultrasonography. Pregnancy diagnosis was accomplished 35 and 66 d post-TAI, respectively, to calculate TAI and end of season pregnancy rates. Neither SB nor SB×PM had an effect (P &gt; 0.37) on apparent ruminal digestion of nutrients compared to the CON. Final BW (414 kg; P ≥ 0.10) and BCS (5.28; P ≥ 0.26) for the heifers were similar among treatments. Likewise, there were no differences in TAI (48%; P &gt; 0.43) or overall breeding season (93%; P &gt; 0.99) pregnancy rates. Ovulatory follicle diameters (11.7 mm) was not different (P &gt; 0.19) among treatments. In summary, forage soybean-based silages, with and without pearl millet, was an acceptable alternative forage for developing replacement beef heifers.

171 ADMINISTRATION OF GnRH ON DAY 6 ALTERS THE NUMBER OF FOLLICULAR WAVES FROM 2 TO 3 DURING THE ESTROUS CYCLE OF HOLSTEIN COWS

2009 ◽  
Vol 21 (1) ◽  
pp. 184
Author(s):  
E. Dirandeh ◽  
H. Kohram ◽  
A. Zare Shahneh
Keyword(s):  
Estrous Cycle ◽  
Prostaglandin F2α ◽  
Control Treatment ◽  
Control Group ◽  
Third Wave ◽  
Estrous Cycles ◽  
Follicular Waves ◽  
Follicular Wave ◽  
Lactating Cows ◽  
Ovulatory Follicle

It is suggested that pregnancy rate is greater in lactating cows inseminated following ovulation of a third-wave follicle compared with a second-wave follicle. The number of follicular waves is not apparent during the estrous cycle. However, GnRH injection on Day 6 is supposed to initiate a new follicular wave earlier; as a result, the number of cows with 3 follicular waves will be increased. This study was done to change the 2-follicular-wave cycles to 3 follicular waves during the estrous cycle. The estrous cycles of 10 cows were synchronized with 2 i.m. injections of prostaglandin F2α given 11 days apart. The cows were randomly assigned to 1 of 2 treatments. Cows in the control treatment received no treatment, whereas GnRH6 cows received a GnRH injection on Day 6 of the estrous cycle (estrus = Day 0). Ovaries of all cows were scanned daily, from estrus (Day 0) to the subsequent estrus (Day 23). Profiles of the mean number of follicles (i.e. 4- to 6-mm and ≥7 mm), the diameter of the largest follicle (F1), and comparison of 2- and 3-wave cows were compared by least squares analysis of variance using the general linear model (GLM) procedure of SAS. The number of 4 to 6 mm follicles had a tendency to decline until Day 6 (3.0 ± 2.1 v. 0.8 ± 1.6). In response to an injection of GnRH, the number of small follicles in group GnRH6 on Day 6 (1.5 ± 1.6 follicles) increased (P < 0.05) on Day 8 (5.0 ± 1.7 follicles) and the number of medium and large follicles (≥7 mm) on Day 6 (1.8 ± 0.5 follicles) decreased (P < 0.05) on Day 9 (0.8 ± 0.6 follicles). Over the 4-day period before GnRH treatment, the diameter of F1 was increasing (from 4.7 ± 0.9 mm to 10.0 ± 0.6 mm) in cows treated with GnRH on Day 6 of the estrous cycle; thereafter, the diameter of the F1 decreased (P < 0.05) within 2 days of GnRH treatment. In the control group the diameter of the F1 increased over the 4-day period before GnRH treatment (from 5.0 ± 0.9 mm to 11.2 ± 0.6 mm), whereas it remained constant (11.2 ± 1.2 mm to 11.2 ± 1.2 mm) between Days 6 and 9 of the estrous cycle (P < 0.003). Results showed that 4 out of 5 cows in control group had 2 follicular waves, whereas all of the cows (n = 5) in GnRH6 group had 3 follicular waves. The first follicular wave begins at Day 1.1 ± 0.50 and 0.70 ± 0.50 in the control and GnRH groups, respectively. The second follicular waves appeared at Day 11.00 ± 0.80 and 8.30 ± 1.50 (P ≤ 0.05) for the 2- and 3-wave animals, respectively. The third follicular waves (n = 6) initiated at Day 16.30 ± 1.50. Cows with 2 follicular waves had shorter estrous cycles (P ≤ 0.05) than 3-wave cows (20.50 ± 0.60 v. 22.40 ± 0.90). The ovulatory follicle in 2-wave cows grew larger (14.00 ± 1.80 v. 12.50 ± 0.90 mm; P ≤ 0.05), and maintained for a longer period of time (9.50 ± 1.80 v. 6.1 ± 0.90; P ≤ 0.05) than in 3-wave cows. In conclusion, an injection of GnRH on Day 6 of the estrous cycle could promote the emergence of a new follicular wave earlier in cows and alter the estrous cycles with 2 waves into 3 follicular waves.

4 EFFECT OF A PROLONGED AROMATASE INHIBITOR TREATMENT ON PRE-OVULATORY OVARIAN FOLLICLES IN CATTLE

2012 ◽  
Vol 24 (1) ◽  
pp. 113 ◽  
Author(s):  
J. Yapura ◽  
J. Singh ◽  
R. J. Mapletoft ◽  
R. Pierson ◽  
D. Rogan ◽  
...  
Keyword(s):  
Aromatase Inhibitor ◽  
Corpus Luteum ◽  
Repeated Measures ◽  
Slow Release ◽  
The Body ◽  
Maximum Diameter ◽  
Dominant Follicle ◽  
Follicular Wave ◽  
Letrozole Treatment ◽  
Intravaginal Device

Letrozole, a non-steroidal aromatase inhibitor, prevents the body from producing its own oestrogen. The potential use of this compound for herd synchronization is supported by previous studies in which letrozole treatment increased mean plasma LH concentrations, prolonged the period of dominance of the extant dominant follicle and delayed emergence of the next follicular wave. Heifers given a 3-day regimen of letrozole exhibited greater corpus luteum diameter indicative of a luteotrophic effect. The objective of the present study was to test the hypothesis that letrozole treatment during the development of the preovulatory follicular wave will delay ovulation. Post-pubertal beef heifers were given 2 luteolytic doses of PGF (12 h apart) and monitored by ultrasonography for ovulation. Ovarian follicular wave emergence was synchronized by ultrasound-guided transvaginal follicular ablation 5 to 8 days after PGF-induced ovulation (Day –1 = follicular ablation, Day 0 = wave emergence) and a luteolytic dose of PGF was given 60 and 72 h later. On Day 1, heifers were divided randomly into 2 groups (n = 15/group) and given an intravaginal device containing 1 g of letrozole or a blank device (control). The intravaginal devices were removed on Day 7, or at the time of ovulation, whichever occurred first. The ovaries were monitored by ultrasonography and a blood sample was collected daily from day of ablation to 12 days post-ovulation. Single point measurements were analysed by t-tests and serial data were analysed by analysis of variance for repeated measures. Multiple contrasts were made by Tukey's test. The interval from placement of the intravaginal device to ovulation was longer in letrozole-treated animals (6.1 ± 0.25 vs 5.1 ± 0.26 days, P < 0.01). Compared with controls, the day-to-day diameter profile of the dominant follicle of the ovulatory wave was larger (P < 0.05) and the maximum diameter greater (14.6 ± 0.51 vs 12.4 ± 0.53 mm; P < 0.01) in letrozole-treated heifers. The diameter profile of the corpus luteum formed post-letrozole treatment did not differ between groups; however, plasma P4 concentrations were higher (P < 0.01) in heifers treated with letrozole. In summary, a slow-release intravaginal letrozole device delayed ovulation by 24 h and induced the formation of a corpus luteum that secreted higher levels of progesterone. A slow-release intravaginal letrozole device may become useful for the development of an aromatase inhibitor-based protocol to control ovulation for herd synchronization and to enhance fertility by increasing circulating progesterone concentrations during the first 7 days post-AI or embryo transfer in cattle. Supported by the Natural Sciences and Engineering Research Council of Canada and Bioniche Life Sciences Inc.

156 Oestrus response, corpus luteum function, and pregnancy rates following aromatase inhibitor treatment in beef heifers

2020 ◽  
Vol 32 (2) ◽  
pp. 204
Author(s):  
E. M. Zwiefelhofer ◽  
M. L. Zwiefelhofer ◽  
J. Singh ◽  
M. G. Colazo ◽  
G. A. Franco ◽  
...  
Keyword(s):  
Aromatase Inhibitor ◽  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Repeated Measures ◽  
Plasma Concentrations ◽  
Prostaglandin F2α ◽  
Pregnancy Rates ◽  
Blood Sampling ◽  
Device Removal ◽  
Letrozole Treatment

In a previous study involving the use of the aromatase inhibitor letrozole to synchronise ovulation, incomplete luteolysis appeared to confound the synchronising effect in letrozole-treated heifers. Experiments were done to determine whether letrozole treatment interferes with luteolysis and affects the timing of oestrus (Experiment 1) and whether pregnancy rate is affected by the stage of the oestrous cycle during which letrozole treatment is initiated (Experiment 2). In Experiment 1, Hereford heifers were fitted with a HeatWatch sensor and given prostaglandin F2α (PGF2α). Ovulation (Day 0) was determined by daily ultrasonography, and on Day 3 heifers were given an intravaginal letrozole-releasing device or a sham device for 4 days (n=16 per group). Half of the heifers in each group were given PGF2α on Day 7 (PGF 1×) or on Day 7 and 7.5 (PGF 2×). Ultrasonography and blood sampling were done daily from device insertion to removal, every 12h for 72h following PGF2α and daily for 14 days following ovulation. In Experiment 2, heifers were randomly assigned to three groups (n=10-11 per group) in which a 4-day letrozole-releasing device treatment was initiated during metoestrus (Days 0-2), diestrus (Days 7-9), or pro-oestrus (Days 15-17). Prostaglandin F2α was given at device removal and again 12h later. Heifers were inseminated with frozen-thawed semen and given gonadotrophin-releasing hormone 66h after device removal. Ultrasonography and blood sampling were done twice daily from device removal until ovulation. End points examined included dominant follicle and corpus luteum (CL) diameters, onset of oestrus, and plasma concentrations of oestradiol determined by radioimmunoassay. Nominal data were compared using GENMOD, analysis of variance, or mixed model for repeated-measures and were expressed as means±s.e.m. Proportional data were analysed using chi-square. In Experiment 1, no main effects or interactions were detected between device or PGF treatment for onset of oestrus following PGF2α (overall 60.0±2.5h) or CL diameter profiles during luteolysis. Residual variation was reduced in the timing of the first PGF to ovulation in the PGF 2× group versus the PGF 1× group (5.6±2.2h vs. 15.2±3.2 h; P&lt;0.01). The CL diameter following ovulation was greater in the PGF 2× group compared with the PGF 1× group (P=0.03). Circulating plasma oestradiol during treatment was greater (P=0.04) in both the PGF 1× and sham groups. In Experiment 2, a greater proportion of heifers in the pro-oestrus group ovulated ≤24h after device withdrawal compared with the metoestrus and diestrus groups combined (6/11 vs. 0/22, respectively; P&lt;0.05). Pregnancy rate tended to be greater in the metoestrus group than in the diestrus group (10/11 vs. 6/10; P=0.08), and pregnancy rate in both groups was greater than that in the pro-oestrus group (0/11; P&lt;0.05). In conclusion, letrozole treatment did not interfere with luteolysis, and PGF2α given 2× at a 12-h interval on Day 7 after ovulation decreased variance in the timing to ovulation. Treatment initiated during metoestrus and diestrus yielded greater pregnancy rates than that started during pro-oestrus and warrants efficacy testing in a large fixed-time AI field trial. This research was supported by Alberta Agriculture and Forestry and by Dechra.

scholarly journals Although it induces synchronized ovulation, hCG reduces the fertility of Santa Ines ewes submitted to TAI

2018 ◽  
Vol 70 (1) ◽  
pp. 122-130 ◽  
Author(s):  
L.M.K. Dias ◽  
J.N.S. Sales ◽  
P. Viau ◽  
M.B.P. Barros ◽  
S.S. Nicolau ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Ovarian Response ◽  
Control Group ◽  
Device Removal ◽  
Oestrus Cycle ◽  
Follicle Diameter ◽  
Ovulatory Follicle ◽  
Santa Inês ◽  
Synchronization Protocol

ABSTRACT The aim of this study was to evaluate hCG treatment on ovarian response and on pregnancy rate using a 9-day oestrus synchronization protocol in Santa Ines ewes. On a random oestrus cycle day, ewes received an intravaginal progesterone device (Primer-PR®, Tecnopec, Brazil). Nine days later (Day 9), 30µg of d-cloprostenol (Prolise®, Syntex, Argentina) and 250IU of eCG (Folligon®, Intervet, Brazil) were administered and the progesterone device was removed. This moment, the ewes were randomly assigned on two groups: Control Group and hCG Group. In the hCG Group, the ewes received 500IU of hCG (Vetecor®, Hertape-Calier, Spain) 24h after device removal. In the Control Group, the ewes did not receive any ovulation inductor. Control and hCG Groups ewes were inseminated 60h and 48h after device removal, respectively. There was no difference between the groups regarding the first ovulatory follicle diameter and the second ovulatory follicle. hCG Group ewes had shorter interval between device removal and ovulation (Control: 79.9±15.4h and hCG: 54.7±4.9h; P=0.001) and more synchronized ovulations. However, the treatment with hCG decreased the pregnancy rate after TAI (P=0,009). In conclusion, hCG administration improves ovulatory synchronisation, but causes a decrease in the pregnancy rate.

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.

scholarly journals PSII-29 Effects of delayed injection of prostaglandin F2α and TAI in the 14-d CIDR-PG & TAI protocol in replacement beef heifers

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 375-376
Author(s):  
Nicky Oosthuizen ◽  
Gabriela Melo ◽  
Lawton Stewart ◽  
George Seidel ◽  
Graham Cliff Lamb ◽  
...  
Keyword(s):  
Prostaglandin F2α ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Transrectal Ultrasonography ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Treatment Groups ◽  
Follicle Diameter ◽  
Randomized Design ◽  
Angus Heifers

Abstract To determine the effects of delaying the injection of prostaglandin F2α (PGF) and fixed-time artificial insemination (TAI) in the 14-d CIDR-PG & TAI protocol, 911 Angus heifers at 5 locations were enrolled in a completely randomized design. Within location heifers were randomly assigned to 1 of 2 treatment groups: 1) PG16 (n = 452), heifers received a CIDR insert on d 0 for 14 d, a 25-mg injection of PGF 16 d after CIDR removal [d 30], and a 100-µg injection of gonadotropin-releasing hormone concurrently with TAI 66 ± 2 h later; or 2) PG17 (n = 459), heifers were treated the same as PG16, however, PGF was administered 17 d after CIDR removal [d 31], and heifers were TAI 66 ± 2 h later. Estrus detection patches were applied to 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 = 171). Furthermore, transrectal ultrasonography was performed to determine pregnancy rates to TAI (PR/AI) between 30 and 45 d after TAI. Estrus expression prior to TAI was similar (P = 0.50) between treatments (48.9 vs. 52.0%, respectively). Moreover, dominant follicle diameter at PGF and TAI was similar (P ≥ 0.43) between PG16 and PG17 heifers. Pregnancy rates to TAI did not differ (P = 0.48) between treatment groups (46.4 vs. 48.9%, respectively). The results of this experiment indicate that delaying the injection of PGF from d 30 to d 31 along with TAI in the 14-day CIDR-PG & TAI protocol had no effects on fertility parameters in beef heifers. In conclusion, the PGF injection and TAI in the 14-d CIDR-PG & TAI protocol may be delayed, providing more flexibility in scheduling without negatively affecting fertility.

scholarly journals 158 Comparison of different presynch-based synchronization protocols in postpartum dairy cattle

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 152-152
Author(s):  
Abid Hussain SHAHZAD ◽  
Shaista Abbas ◽  
Iahtisham Khan ◽  
raafia safdar ◽  
Ali Abbas ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Pregnancy Rate ◽  
Pregnancy Loss ◽  
Chi Square ◽  
Reproductive Management ◽  
Lactating Cows ◽  
Ovarian Status ◽  
Follicle Diameter ◽  
Ovulatory Follicle ◽  
Chi Square Test

Abstract Objectives were to evaluate three timed AI presynch-based synchronization protocols in lactating Holstein-Frisian cattle. Lactating cows (n = 207) were randomly divided into one of the three treatments: 1)PG-PG-Ovsynch (n = 71), cows were subjected to PG(PGF2α;i.m) at 11-d apart. On 11d post 2nd PG shot, standard Ovsynch (GnRH PG–GnRH) was introduced, 2) G7G-Ovsynch(n = 59), PGF2α-2d-GnRH-7d-Ovsynch, 3) Ovsynch-Ovsynch(n = 67), Ovsynch-7d-Ovsynch. Progesterone profile was measured on d30 and d60 post TAI. For monitoring of ovarian status ultrasonography was done at 1st GnRH, PG and 2nd GnRH of the breeding protocol. Pregnancy was diagnosed on d30, 60 and 90 post TAI and pregnancy loss was also on d60 and 90 post TAI. Pregnancy data was analyzed using Chi-square test and plasma P4 profile by ANOVA in SAS. Ovulatory follicle diameter (mean± SD) was 15.02±1.05 in PG-PG-Ovsynch, 15.41±1.28 in G7G-Ovsynch and 15.23±1.23 in Ovsynch-Ovsynch, respectively (P = 0.167). Plasma P4 profile (ng/mL;Mean±SD) on d30 post TAI was 6.46±1.54,7.07±1.19 and in 6.65±1.40 PG-PG-Ovsynch, G7G-Ovsynch and Ovsynch-Ovsynch groups, respectively (P = 0.08). On d60 post TAI, P4 profile was recorded to be 7.35±1.16,8.06±1.27 and 7.81±0.91 in PG-PG-Ovsynch, G7G Ovsynch and Ovsynch Ovsynch, respectively (P = 0.005). Pregnancy rate on day 30 was 50.70(36/71), 58.20(39/67) and 52.50(31/59) in PG-PG-Ovsynch, G7G-Ovsynch and Ovsynch-Ovsynch, respectively (P = 0.88). Similarly,PR on d60 and d90 post TAI was 46.50(33/71):43.70(31/71), 55.20(37/67): 53.70(36/67) and 50.80(30/59):47.50(28/59) in PG-PG-Ovsynch, G7G-Ovsynch and Ovsynch-Ovsynch groups (P = 0.84:0.78), respectively. Pregnancy loss on d60 post TAI was 8.30,5.0 and 3.20% in PG-PG-Ovsynch, G7G-Ovsynch and Ovsynch-Ovsynch, respectively (P = 0.69). Although statistically non-significant (P = 0.73), overall pregnancy loss on d90 post TAI was also numerically higher in PG-PG-Ovsynch(14.0%) protocol as compared to G7G-Ovsynch (8.30%) and Ovsynch-Ovsynch (9.70%). We concluded that G7G-Ovsynch protocol has resulted in increased PR, P4 profile in comparison with PG-PG-Ovsynch and Ovsynch Ovsynch. Similarly, reduced pregnancy loss,ease and economics makes G7G-Ovsynch as a protocol of choice for improved reproductive management in postpartum dairy cows.

scholarly journals PSV-18 The role of leptin in feed efficiency and behavior attributes of commercial beef heifers

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 162-162
Author(s):  
Nayan Bhowmik ◽  
Kris A Ringwall ◽  
Carl R Dahlen ◽  
Kendall C Swanson ◽  
Jeffrey A Clapper ◽  
...  
Keyword(s):  
Feeding Behavior ◽  
Breeding Season ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Beef Heifers ◽  
Frame Size ◽  
And Behavior ◽  
Plasma Leptin

Abstract Leptin is a 16-kDa-peptide hormone product of the leptin gene (LEP) that is predominantly synthesized by adipose tissues and has known involvement in regulation of feed intake, energy expenditure, reproduction, and immune functions. The objective was to determine the association of leptin genotype (LEP c.73C &gt;T), leptin diplotype (LEPD) and plasma leptin hormone (LEPH) concentration with growth, feed intake, feed efficiency, and behavior characteristics in developing beef heifers. A total of 336 commercial beef heifers were genotyped for the LEP c.73C &gt;T marker. Four single nucleotide polymorphism markers including LEP c.73C &gt;T, ARS-BFGL-NGS-59298 (intron 1), BovineHD0400026029 (upstream) and BovineHD0400026063 (downstream) of LEP were considered for haplotype analysis. Eleven LEPD were identified for this study using parsimony-based analyses. Circulating levels of LEPH were measured on 333 heifers prior to their first breeding season and used to assign low or high concentration group based on population median. Data were analyzed using the mixed procedure of SAS for repeated measures, fixed effects of ancestral breed group (n = 4), dam age category (n = 4), frame size group (n = 4), project cycle nested within birth year (n = 6), week of feed trial × year, LEP (n = 3) or LEPD (n = 11) or LEPH (n = 2), as well as week × LEPH (only for LEPH). There were no significant differences between LEP genotypes (P ≥ 0.11) or LEPD (P ≥ 0.33) for any of the studied traits. Heifers with low LEPH ate fewer meals per day (P = 0.02) and had more DMI per meal (P = 0.04) compared to those with high plasma leptin. Further research is needed to better understand plasma LEPH concentration and its role in feeding behavior attributes. However, circulatory LEPH before the breeding season may serve as a predictor for feeding behavior.

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