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1.
The aim of this study was to compare pregnancy per artificial insemination (P/AI) after timed AI with sex‐sorted sperm (SS) or conventional semen (CS) in lactating dairy cows. Cyclic cows (n = 302) were synchronized by Ovsynch and randomly assigned into two groups at the time of AI. Cows with a follicle size between 12 and 18 mm and clear vaginal discharge at the time of AI were inseminated with either frozen‐thawed SS (n = 148) or CS (n = 154) of the same bull. A shallow uterine insemination was performed into the uterine horn ipsilateral to the side of probable impending ovulation. Pregnancy per AI on Day 31 tended (p = 0.09) to be less for SS (31.8%) than CS (40.9%). Similarly, P/AI on Day 62 was less (p = 0.01) for cows inseminated with SS (25.7%) compared with CS (39.0%). The increased difference in fertility between treatments from Days 31 to 62 was caused by the greater (p = 0.02) pregnancy loss for cows receiving SS (19.2%) than CS (4.8%). Cow parity (p = 0.02) and season (p < 0.01) when AI was performed were additional factors affecting fertility. Primiparous cows had greater P/AI than multiparous cows both on Day 31 (41.7% vs 25.0% in SS and 53.0% vs 31.8% in CS groups) and on Day 62 (33.3% vs 20.5% in SS and 48.5% vs 31.8% in CS groups). During the hot season of the year, P/AI on Day 31 was reduced (p = 0.01) in the SS group (19.6%) when compared with the rates during the cool season (38.1%). In conclusion, sex‐sorted sperm produced lower fertility results compared to conventional semen even after using some selection criteria to select most fertile cows.  相似文献   

2.
Pregnancy rate per AI (PR/AI) and breeding season pregnancy rates between insemination with sexed semen (SS; at 18 hr after the onset of oestrus) and conventional semen (CS; at 12 hr after the onset of oestrus,) and offspring gender ratio between two groups were compared. Angus cross cows (n = 686, during 2019 and 2020 breeding seasons) were oestrus-synchronized using Select-Synch + CIDR protocol and were observed thrice daily for oestrus until 72 hr after PGF2α administration. Cows expressed oestrus (n = 513) were inseminated with either SS (n = 246; SexedULTRA 4M™; y chromosome-bearing sperm) or CS (n = 267). Cows (n = 173) that failed to express oestrus at 72 hr after PGF2α received 100 μg of GnRH and CS insemination concomitantly. Two weeks later, cows were penned with natural service sires (bull:cow ratio 1:25) for 45 days. Pregnancy was diagnosed 30 days after bull removal. Calves' gender was determined at birth. For cows that expressed oestrus, PR/AI did not differ (p > .1) between SS (65.0%) and CS (66.7%) groups. The overall PR/AI differed (p < .05) between SS (65.0%) and CS (56.4%) groups. The natural service PR differed (p < .001) but breeding season PR (p > .05) did not differ between SS vs. CS groups. Bull:heifer gender ratio following AI was 88:12 and 52:48 for SS and CS groups, respectively, with an overall 66:34 ratio. Bull:heifer gender ratio for the two breeding seasons was 79:21 and 52:48 for SS and CS groups, respectively, with an overall 62:38 ratio. In conclusion, the fertility of SS insemination at 18 hr after onset of oestrus was 97% of CS insemination at 12 hr after onset of oestrus. Though breeding season pregnancy did not differ between SS and groups, preferred calf gender was 25 percentage points greater for SS over CS application. The gender accuracy was 88%.  相似文献   

3.
The main objective was to investigate the effects of timed-AI protocols versus AI following oestrus detection on circulating progesterone (P4) and embryo survival after first service in Holstein cows. Cycling status was determined by ultrasonography and by plasma P4 concentrations 14 and 26 days after calving, and only cows with a corpus luteum and/or P4 ≥ 1 ng/ml were used. Cows were randomly allocated to one of three types of breeding: DO (n = 80), received GnRH-7d-PGF2α-3d-GnRH and Ovsynch56 was initiated 7 days later; G7G (n = 70), received PGF2α-2d-GnRH and Ovsynch56 (GnRH-7d-PGF2α-56h-GnRH-16h-AI) was initiated 7 days later; or AI based on oestrus detection, EDAI (n = 60). Progesterone was also determined at AI and 8, 16, 18 and 20 days after AI; ISG15 and MX2 mRNA abundance were determined 16 days after AI. Mean plasma P4 at AI was greater in the EDAI group compared with DO and G7G groups, while after AI, P4 was greater in DO and G7G groups compared with EDAI group. However, the percentage of cows with a concentration of P4 < 0.8 ng/ml at AI did not differ among groups. Relative mRNA abundance of ISG15 and MX2 was greater in the DO and G7G groups compared to those in EDAI group. Pregnancy per AI 16, 32 and 60 days after AI was greater (p < .05) in cows in the DO group compared with those in EDAI group (47.5%, 38.8% and 36.3% vs. 30.0%, 21.7% and 15.0%). Pregnancy losses between 16 and 60 days after AI were greater (p < .05) in cows in the EDAI (50.0%) group compared to those subjected to DO (23.7%) or G7G (24.1%). In conclusion, the use of timed-AI synchronization protocols resulted in greater circulating P4 concentrations post-AI and greater embryo survival following first service in lactating Holstein cows.  相似文献   

4.
The objectives were to evaluate the reproductive indices and survival analysis of pregnancy outcomes in multiparous repeat breeder Holstein cows (n = 557). The cows were synchronized to ovulate by Ovsynch, new controlled internal drug release device (N‐CIDRsynch), and once‐used CIDR device (U‐CIDRsynch). The pregnancy per AI at 28 days post‐insemination (P/AI 28) in the N‐CIDRsynch group (28.75%) was significantly (COR = 1.49; p = 0.011) greater than that reported in the Ovsynch (23.46%) and U‐CIDRsynch (21.73%) groups. Furthermore, the pregnancy per AI at day 75 post‐insemination (P/AI 75) in the N‐CIDRsynch group was significantly greater than the Ovysync group (COR = 1.35; p = 0.050). The repeat breeder cows received a N‐CIDR device had a significantly higher progesterone level on day 2 and day 4 of CIDR insertion (1.38 and 1.67 ng/ml, respectively) than those received a U‐CIDR device or the control group (p = 0.012 and 0.001, respectively). The Cox regression model recorded significant associations for synchronization protocols, THI at the TAI and season of calving with the hazard of P/AI 28 and P/AI 75 (p = 0.044 and 0.046; 0.001 and 0.005; 0.003 and 0.001, respectively). Multiparous repeat breeder cows (>3) had a lower hazard ratio (HR) of P/AI 28 than that reported in the reference (2nd parity) group (HR = 0.74, p = 0.050). The repeat breeder cows inseminated at 76–80 and >80 temperature‐humidity index (THI) had significantly lower HR of P/AI 28 than those inseminated at the baseline (<70) THI value (HR = 0.73 and 0.30, p = 0.036 and 0.001, respectively). The current results indicate that the use of N‐CIDR synch protocol may achieve satisfactory pregnancy outcomes in repeat breeder cows.  相似文献   

5.
The present study was designed to compare the reproductive performance of pre-synchronized post-partum dairy cows subjected, either to the Ovsynch protocol without screening for ovarian status (control group), or to a specific oestrous synchronization protocol applied according to their ovarian status, as determined by transrectal ultrasound (experimental group). The study was conducted on 428 lactating dairy cows. Cows in the Ovsynch group (n = 205) were synchronized and time inseminated after receiving the Ovsynch protocol treatment. Cows in the specific synchronization (Ssynch) group (n = 223) were weekly subjected to transrectal ultrasound exams for 4 weeks, or until AI or starting treatment, and divided into four subgroups according to their ovarian status: (i). corpus luteum (CL) subgroup (n = 130), cows with a CL; (ii). natural oestrus (NE) subgroup (n = 58), cows showing NE; (iii). anovulatory follicles (AF) subgroup (n = 26), cows considered to have AF; and (iv). ovarian cysts (OC) subgroup (n = 9), cows with OC. Cows in the Ssynch group were synchronized and time inseminated following a specific oestrous synchronization protocol, or inseminated at NE. Logistic regression analysis was carried out for the dependent variables ovulation and pregnancy rates to first and to second AI (second AI: first AI + return AI). Cows subjected to Ssynch were 2.1 times more likely to become pregnant at first and at second AI compared with those synchronized using the Ovsynch protocol (P < 0.0001). Our results show that the response of post-partum pre-synchronized cows to a specific oestrous synchronization protocol applied according to their ovarian status is more effective than the response to the Ovsynch protocol applied without taking into account the ovarian status of the animals.  相似文献   

6.
The objective of this retrospective study was to assess the effect of receiving a single (n = 50,285) or double (n = 4392) artificial insemination (AI), 12 h apart, within a timed artificial insemination protocol on pregnancy per AI (P/AI) in nulliparous heifers (inseminated with either sex-sorted or conventional semen) and pluriparous Holstein cows in a commercial dairy herd. Also, this study aimed to investigate the relationship between temperature-humidity index (THI) and time of the first AI and fertility. Fertility of cows receiving two AI with normothermia (THI <68) was higher (p < .05) than cows receiving a single AI (42.9% vs. 36.4%). P/AI of cows receiving two AI with severe heat stress (THI >85) was higher (p < .05) than cows receiving a single AI (21.0% vs. 12.6%). Regardless of heat stress conditions, applying the first AI in the morning increased (p < .05) P/AI in cows with double AI than in cows whose first AI occurred in the afternoon (38.4 vs. 33.3%). With moderate heat stress, and sexed-sorted semen, P/AI to timed AI was higher (65.0 vs. 51.9%; p < .05) in heifers receiving double AI than those serviced once. It was concluded that double AI, 12 h apart, enhanced fertility at timed AI than herd mates with a single AI, particularly with heat stress at breeding.  相似文献   

7.
Crossbred cows (n = 1073) from five locations had oestrous cycles synchronized with 100 μg of GnRH IM and insertion of controlled internal drug release device (CIDR) on Day 0 followed by 25 mg of PGF2α IM and CIDR removal on Day 7. Kamar® patches were placed on all cows at CIDR removal. Cows were observed three times daily for oestrus after PGF2α administration. In the Ovsynch‐CIDR group, cows detected in oestrus (n = 193) within 48 h after PGF2α were inseminated using the AM–PM rule. Among these cows, 80 received and 113 did not receive a second GnRH at 48 h after PGF2α. Cows (n = 345) not detected in oestrus received a second GnRH at 48 h after PGF2α on Day 9, and fixed‐time AI 16 h after the GnRH on Day 10. In the CO‐Synch‐CIDR group, cows detected in oestrus (n = 224) within 48 h after PGF2α were inseminated using the AM–PM rule. Among these cows, 79 received and 145 did not receive a second GnRH at 64 h after PGF2α. Cows (n = 311) not detected in oestrus received a second GnRH on Day 10 at the time of AI, 64 h after PGF2α. The AI pregnancy rates were not different between the Ovsynch‐CIDR and CO‐Synch‐CIDR groups (p = 0.48). There were no differences in the AI pregnancy rates for cows inseminated at a fixed time (p = 0.26) or at detected oestrus (p = 0.79) between the treatment groups. Among cows inseminated in oestrus, there were no differences in the AI pregnancy rates between cows that received or did not receive the second GnRH (p = 0.47). In conclusion, acceptable AI pregnancy rates can be achieved with or without inclusion of oestrus detection in the Ovsynch‐CIDR and CO‐Synch‐CIDR protocols. Among cows detected in oestrus, cows that received a second GnRH yielded similar pregnancy rates when compared with cows that did not receive the second GnRH.  相似文献   

8.

The objective of this study was to evaluate the fertility of sexed semen compared with conventional semen with regard to the puberty and breeding ages of Holstein dairy heifers subjected to double Ovsynch protocol with fixed time of artificial insemination. A total of 468 Holstein heifers were divided into two groups. The first group was 122 dairy heifers inseminated via conventional semen, while the second group was 346 heifers inseminated with sexed semen. The puberty and breeding ages of heifers were determined from the farm records. Estrus was synchronized using the double Ovsynch protocol. Numbers were estimated for pregnancy at 40 and 60 days post insemination, embryonic loss, and abortion. The results revealed that the heifers inseminated with sexed semen had a significantly lower first-service pregnancy rate (51.45%) than those inseminated with conventional semen (61.47%). Heifers achieving puberty before 350 days old had a higher pregnancy rate. Embryonic losses and abortion rates did not differ between the two types of semen. Holstein heifers subjected to Ovsynch protocol with sexed semen had an acceptable first-insemination pregnancy rate. Even the applications of sexed semen reduce the reproductive fertility and pregnancy rate in Holstein heifers.

  相似文献   

9.
The objective of the study was to compare the fertility after using sex-sorted or conventional semen either with oestrus detection (EST) or timed artificial insemination (TAI) in Holstein heifers. Holstein heifers were randomly assigned to one of the following treatments in a 2 × 2 factorial design. Heifers in the EST group were inseminated with sex-sorted (n = 114) or conventional semen (n = 100) after spontaneous or induced oestrus. Heifers in the TAI, subjected to the 5-day Cosynch+Progesterone protocol (GnRH+P4 insertion-5d-PGF2α+P4 removal-1d-PGF2α-2d-GnRH+TAI), were inseminated with sex-sorted (n = 113) or conventional semen (n = 88). Statistical analyses were performed using PROC GLIMMIX procedure of SAS 9.4 (SAS Institute Inc., Cary, NC). Overall P/AI was 60.7% for EST and 54.2% for TAI regardless of types of semen and 68.1% for conventional and 48.9% for sex-sorted semen regardless of insemination strategies. Fertility of heifers inseminated with either sex-sorted (53.5%; 44.2%) or conventional (69.0%; 67.0%) semen did not differ between EST and TAI respectively. Besides, the interaction between the semen type and the insemination strategy was not significant for P/AI. The embryonic loss was significantly greater with sex-sorted semen (17.1%) compared to conventional semen (1.6%). There was no sire effect with sex-sorted semen on P/AI (52.6% vs. 46.2%) and embryonic loss (16.4% vs. 18.0%). As expected, sex-sorted semen resulted in more female calves (89.8% vs. 51.6%) than conventional semen. Thus, sex-sorted semen can be used with 5-day Cosynch+Progesterone protocol to eliminate the inadequate oestrus detection and to increase female calves born in dairy heifers.  相似文献   

10.
The study aimed to evaluate pregnancy per artificial insemination (P/AI) of cows subjected to synchronization and resynchronization in ovulation protocols using intravaginal progesterone‐releasing insert (P4) before pregnancy diagnosis (PD) and the relationship of PR with the diameter of preovulatory follicles (ØPOF) before TAI. Cows (n = 378) were distributed into two groups: a resynchronization group with new devices (GRN; n = 185) and resynchronization group with used devices (GRU; n = 193). On Day 0, both groups received a new P4 and estradiol benzoate (EB). On D8, P4 removal + D‐cloprostenol + eCG + estradiol cypionate (EC) was done. On d10, TAI was conducted. On d32, cows were resynchronized and divided into two groups, GRN (n = 185) and GRU (n = 193). The GRN group received a new P4 + EB, and the GRU group received a used P4 + EB. On d40, the P4 was removed + PD. The non‐pregnant cows received D‐cloprostenol + eCG + EC. US was done again on d42 to determine ØPOF before the second TAI. The P/AI of the GRN and GRU groups after synchronization were 56.2% and 57.0% (p = 0.87), respectively, and those after resynchronization were 58.0% and 37.3% (p < 0.008), respectively. The P/AI of the GRN and GRU groups observed after TAI (synchronization + resynchronization) were 81.6% and 73.1%, respectively (p = 0.047). No difference (p = 0.067) in ØPOF between the pregnant and non‐pregnant cows in the GRN was found, whereas the GRU group showed a significant difference (p = 0.003). Resynchronization protocols optimized the P/AI in both groups. New intravaginal devices resulted in greater P/AI and P/AI accumulation in resynchronization as compared with the GRU; the ØPOF was related with P/AI.  相似文献   

11.
The main objective of this study was to assess the effect of month of breeding on reproduction performance of Holstein heifers and cows inseminated with sex-sorted or conventional semen in a hot environment. Pregnancy per artificial insemination (P/AI; 64,666 services over an 8-year period) both in heifers (n?=?22,313) and cows (n?=?42,353) from a large dairy herd in northern Mexico (26°N) were evaluated with the GENMOD procedure of SAS, with respect to month of AI. Overall, P/AI with sex-sorted semen was greater (P?<?0.01) in heifers (41.6 %) than cows (17.3 %). P/AI for cows serviced with conventional semen was 10 % points higher (P?<?0.01) in January and December (31 vs. 21 %) than cows serviced with sex-sorted semen. While there was no difference in P/AI between the sex-sorted sperm and conventional semen in cows inseminated in July (16 and 18 %, respectively), P/AI plummeted for both groups of cows during the summer and fall (more severe heat stress). P/AI was not different between heifers serviced with sex-sorted or conventional semen during the hottest months of the year (July to October). However, during the coldest month of the year (January and February), P/AI was 10 percentage points greater (P?<?0.01) in heifers serviced with conventional than sex-sorted semen. It was concluded that in this hot climate cow and heifer fertility declined in the summer and fall when inseminated with conventional semen. However, the use of sex-sorted semen during summer and fall did not compromise the breeding success in heifers. Thus, this data suggest that sex-sorted semen promotes some embryonic thermoprotective mechanism, which leads to a marginal summer and fall fertility depression with this type of semen in this particular hot environment.  相似文献   

12.
Objectives were to evaluate risk factors affecting ovulatory responses and conception rate to the Ovsynch protocol. Holstein cows, 466, were submitted to the Ovsynch protocol [day 0, GnRH‐1; day 7, prostaglandin (PG) F2α; day 9, GnRH‐2] and 103 cows were inseminated 12 h after GnRH‐2. Information on parity, days in milk at GnRH‐1, body condition, milk yield, exposure to heat stress, pre‐synchronization with PGF2α and the use of progesterone insert from GnRH‐1 to PGF2α was collected. Ovaries were scanned to determine responses to treatments. Overall, 54.7%, 10.6%, 2.2%, 81.1%, 9.0%, 91.5% and 36.9% of the cows ovulated to GnRH‐1, multiple ovulated to GnRH‐1, ovulated before GnRH‐2, ovulated to GnRH‐2, multiple ovulated to GnRH‐2, experienced corpus luteum (CL) regression and conceived, respectively. Ovulation to GnRH‐1 was greater in cows without a CL at GnRH‐1, cows with follicles >19 mm and cows not pre‐synchronized with PGF2α 14 days before GnRH‐1. Multiple ovulations to GnRH‐1 increased in cows without CL at GnRH‐1 and cows with follicles ≤19 mm at GnRH‐1. Ovulation before GnRH‐2 was greater in cows without CL at PGF2α. Ovulation to GnRH‐2 increased in cows that received a progesterone insert, cows with a CL at GnRH‐1, cows with follicles not regressing from the PGF2α to GnRH‐2, cows with larger follicles at GnRH‐2, cows that ovulated to GnRH‐1 and cows not pre‐synchronized. Multiple ovulations after GnRH‐2 increased in cows with no CL at GnRH‐1, multiparous cows and cows that multiple ovulated to GnRH‐1. Conception rate at 42 days after AI increased in cows with body condition score > 2.75 and cows that ovulated to GnRH‐2. Strategies that optimize ovulation to GnRH‐2, such as increased ovulation to GnRH‐1, should improve response to the Ovsynch protocol.  相似文献   

13.
Previous studies have shown that the use of beef bull semen significantly reduces the rate of abortions due to Neospora caninum in artificially inseminated (AI) seropositive dairy cows. In addition, certain beef breeds could be more resistant to N. caninum infection and abortion than others. The aim of the present study was to determine whether different crossbreed pregnancies, those derived from Limousin, Charolais, Piedmontese or Belgian Blue semen, carry different risks of abortion in Neospora-infected dairy cows. The effects of possible interactions between maternal levels of N. caninum antibodies and the different breed crosses were also evaluated. The study was performed on five commercial Holstein–Friesian dairy herds in Northeast Spain with previously confirmed diagnoses of N. caninum infection in aborted foetuses. The study population was comprised of 1115 pregnancies: 633 pregnancies recorded after AI using Holstein–Friesian semen from 18 bulls and 482 after AI using beef semen from 27 bulls (304 inseminations using semen from Limousin bulls, 191 from Belgian Blue bulls, 89 from Piedmontese bulls and 49 from Charolais bulls). Abortion rates were 32.2% (155/482) and 15.2% (96/633) for seropositive cows inseminated with Holstein–Friesian and beef breed semen, respectively. Logistic regression analysis revealed the herd and the interaction between maternal N. caninum antibody titre and the different crossbreeds as significant factors affecting the abortion rate. Lowest abortion rates, similar to that shown by seronegative animals in the analysed herds (3.2%, 239/7432), were observed in dams AI using Limousin semen that had low (<30 relative index (RI) units) N. caninum antibody titres (2.1% abortion, 3/145) and these cows were used as reference. Compared to the cows used as reference, cows with low N. caninum antibody titres (<30 RI units) showed a similar risk of abortion when inseminated with Piedmontese or Charolais bull semen, but higher risk of abortion when inseminated with Holstein (17.9 times) or Belgian Blue (7.2 times) bull semen. All cows with high N. caninum antibody titres (≥30 RI units) had a higher risk of abortion, ranging from 8.9 times (cows inseminated with Limousine semen) to 37.8 times (cows inseminated with Piedmontese semen), compared to the cows used as reference. In conclusion, different crossbreed pregnancies carried different abortion risks in Neospora-infected dairy cows. The use of beef bull semen dramatically reduced the risk of abortion in dairy cows, especially if Limousin breed semen was used. Moreover, this reduction was found to be dependent on the N. caninum antibody titre such that the lowest incidence of abortions was recorded in Limousin semen inseminated cows with low antibody titres. Insemination of Neospora-seropositive cows with beef bull semen could both reduce the risk of abortion and avoid breeding replacements for infected cattle.  相似文献   

14.
Beef cows (n = 473) from two locations were stratified by breed, postpartum interval, age, and AI sire and were randomly allotted to one of four treatments for synchronization of ovulation. Ovulation synchronization protocols included the Ovsynch protocol with (n = 114) or without (n = 123) 48-h calf removal from d 7 to 9 (d 0 = 1st GnRH injection) or the CO-Synch protocol with (n = 119) or without (n = 117) 48-h calf removal from d 7 to 9. The Ovsynch protocol included administration of GnRH (100 microg; i.m.) on d 0, PGF2alpha (25 mg; i.m.) on d 7, GnRH (100 microg; i.m.) on d 9, and timed insemination on d 10. The CO-Synch protocol included administration of GnRH (100 microg; i.m.) on d 0, PGF2alpha (25 mg; i.m.) on d 7, and GnRH (100 microg; i.m.) with timed insemination on d 9. Blood samples were collected from all cows on d -10 and d 0 for analysis of serum progesterone. Cows with at least one serum progesterone concentration greater than 1 ng/mL were considered to be cyclic at the time of treatment. Conception rates of cows that received the CO-Synch + calf removal, Ovsynch + calf removal, CO-Synch, or Ovsynch protocol (63, 61, 54, and 52%, respectively) were not different (P = 0.50). Conception rates were not different (P = 0.80) among CO-Synch- and Ovsynch-treated cows; however, both estrual status and 48-h calf removal affected conception rates. Conception rates of cyclic cows (66%) were greater (P = 0.01) than those of anestrous cows (53%), regardless of which synchronization protocol was used. When data were pooled across synchronization protocol, conception rates of cows with 48-h calf removal (62%) were greater (P = 0.09) than conception rates of cows without calf removal (53%). The CO-Synch + calf removal protocol induces a fertile ovulation in cyclic and anestrous cows, requires handling cattle just three times, results in high conception rates from timed insemination, and should be a useful program for synchronization of ovulation in beef cows.  相似文献   

15.
The objective of the study was to evaluate the interval from onset of oestrus to time of artificial insemination (AI) to obtain the optimum pregnancy rate with sex-sorted semen in Holstein heifers. Heifers in oestrus were detected and inseminated only by using heat–rumination neck collar comprised electronic identification tag at the age of 13–14 months. Heifers (n = 283) were randomly assigned to one of three groups according to the timing of insemination at 12–16 hr (G1, n = 97), at 16.1–20 hr (G2, n = 94) and at 20.1–24 hr (G3, n = 92) after reaching the activity threshold. The mean duration of oestrus was 18.6 ± 0.1 hr, and mean peak activity was found at 7.5 ± 0.1 hr after activity threshold. The mean interval from activity threshold to ovulation was 29.4 ± 0.4 hr. The overall pregnancy per AI (P/AI) was 53.0% at 29–35 days and 50.9% at 60–66 days after AI. There was a significant reduction between G1 (13.8 ± 1.4 hr) and G3 (7.9 ± 1.4 hr) related to the intervals from AI to ovulation time. Sex-sorted semen resulted in significantly higher P/AI at 29–35 days when heifers inseminated in G3 (60.9%) after oestrus than those inseminated in G1 (49.5%) and G2 (48.9%). In terms of fertility, when the temperature–humidity index (THI) was below the threshold value (THI ≤65) at the time of AI, there was a tendency (≤65; 57.2% vs. > 65; 47.1%) for high pregnancy rate. There was no effect of sire on P/AI. In addition, the interaction of the technician with the time of AI was found significant, and three-way interaction of technician, sire and time of AI was tended to be significant on pregnancy rate. Thus, in addition to delaying the time of insemination (between 20.1 and 24 hr) after oestrous detection, THI and experienced technician were also found to be critical factors in increasing fertility with the use of sex-sorted semen in Holstein heifers.  相似文献   

16.
The objective was to compare embryo yield and quality in lactating dairy cows superovulated (SO) with varying amounts of gonadotropins and FSH:LH ratios and inseminated with SexedULTRA? sex‐sorted semen. The SO treatments (n = 77) involved 3 protocols: groups F700 and F1000 were given total doses of 700 and 1,000 IU of Folltropin (FSH:LH ratio 49:1), respectively, whereas group F700P300 was given 700 IU of Folltropin + 300 IU of Pluset (FSH:LH ratio 1:1). Cows were artificially inseminated 3 times over a 10‐hr interval with frozen‐thawed SexedULTRA? sex‐sorted semen (total of 10 × 106 sex‐sorted sperm), starting 18 hr after onset of oestrus, with embryos/ova recovered 7 d after oestrus. Total number of recovered structures and transferable embryos were lower (p < 0.05) in F700 (4.7 ± 3.0 and 1.9 ± 1.7, respectively; mean ± SD) compared to F1000 (8.1 ± 3.8 and 4.4 ± 2.6) and F700P300 (8.5 ± 6.4 and 4.5 ± 3.3). Percentage of cows ovulating >50% of follicles ≥0.8 cm in diameter was lower (p < 0.05) in F700 (35.5%) than in F1000 (82.4%) and F700P300 (73.1%). Percentage of unfertilized oocytes was higher (p < 0.05) in F700 (45.0% vs. 27.7% for F1000 and 29.0% for F700P300) whereas percentage of morulae was higher (p < 0.05) in F1000 (19.3% vs. 8.7% for F700 and 12.2% for F700P300). Embryo quality was similar among groups (p > 0.05). In conclusion, embryo production in lactating dairy cows was improved by increasing total dose of gonadotropins from 700 to 1,000 IU, with SexedULTRA? sex‐sorted semen yielding satisfactory fertilization rates and embryo quality.  相似文献   

17.
The objectives were (i) to evaluate the effect of temperament, determined by modified 2‐point chute exit and gait score, on artificial insemination (AI) pregnancy rates in beef heifers following fixed time AI and (ii) to determine the effect of temperament on cortisol, substance‐P, prolactin and progesterone at initiation of synchronization and at the time of AI. Angus beef heifers (n = 967) at eight locations were included in this study. At the initiation of synchronization (Day 0 = initiation of synchronization), all heifers received a body condition score (BCS), and temperament score (0 = calm; slow exit and walk or 1 = excitable; fast exit or jump or trot or run). Blood samples were collected from a sub‐population of heifers (n = 86) at both synchronization initiation and the time of AI to determine the differences in serum progesterone, cortisol, prolactin and substance‐P concentrations between temperament groups. Heifers were synchronized with 5‐day CO‐Synch+ controlled internal drug release (CIDR) protocol and were inseminated at 56 h after CIDR removal. Heifers were examined for pregnancy by ultrasound 70 days after AI to determine AI pregnancy. Controlling for synchronization treatment (p = 0.03), facility design (p = 0.05), and cattle handling facility design by temperament score interaction (p = 0.02), the AI pregnancy differed between heifers with excitable and calm temperament (51.9% vs 60.3%; p = 0.01). The alley‐way with acute bends and turns, and long straight alley‐way had lower AI pregnancy rate than did the semicircular alley‐way (53.5%, 56.3% and 67.0% respectively; p = 0.05). The serum hormone concentrations differed significantly between different types of cattle handling facility (p < 0.05). The cattle handling facility design by temperament group interactions significantly influenced progesterone (p = 0.01), cortisol (p = 0.01), prolactin (p = 0.02) and substance‐P (p = 0.04) both at the initiation of synchronization and at the time of AI. Inter‐ and intra‐rater agreement for temperament scoring were moderate and good (Kappa = 0.596 ± 0.07 and 0.797 ± 0.11) respectively. The predictive value for calm and pregnant to AI was 0.87, and excited and non‐pregnant to AI was 0.76. In conclusion, the modified 2‐point temperament scoring method can be used to identify heifers with excitable temperament. Heifers with excitable temperament had lower AI pregnancy. Further, cattle handling facility design influenced the temperament and AI pregnancy.  相似文献   

18.
The objective of this study was to characterize the effect of dose and type of cloprostenol (CLO) on the luteolytic response of dairy cattle during the Ovsynch protocol under different oestrus cycle and physiological characteristics. Twelve non‐lactating dairy cows and 111 lactating dairy cows were used in three experiments. In Experiment I, cows were synchronized so that they had only a 5.5‐ to 6‐day‐old corpus luteum (CL) at the time of the prostaglandin F2α (PGF2α) treatment of Ovsynch. In Experiment II, cows were synchronized so that they had at least a CL of approximately 14 days old at the time of PGF2α treatment and an accessory CL if they had responded to the first GnRH of Ovsynch. Furthermore, in each experiment, cows received either a standard or a double dose of d‐CLO as the luteolytic treatment. In Experiment III, lactating cows were blocked by parity and assigned to one of three luteolytic treatments during Ovsynch: 500 μg d,l‐CLO, 150 or 300 μg of d‐CLO. In Experiment I, the dose of d‐CLO had an effect (p = 0.08) on the percentage of cows with full luteolysis, but not in Experiment II (p > 0.1). More cows in Experiment II had full luteolysis than did cows of Experiment I (87% vs 58%, respectively; p = 0.007). In Experiment III, 87.1%, 84.4% and 86.2% lactating dairy cows had full luteolysis and 37.8%, 36.8% and 36.1% of cows became pregnant after treatment with 500 μg d,l‐CLO, 150 or 300 μg of d‐CLO, respectively (p > 0.05).  相似文献   

19.
This study compared artificial insemination pregnancy rate (AI‐PR) between 14‐day CIDR‐GnRH‐PGF2α‐GnRH and CIDR‐PGF2α‐GnRH synchronization protocol with two fixed AI times (56 or 72 hr after PGF2α). On day 0, heifers (n = 1311) from nine locations assigned body condition score (BCS: 1, emaciated; 9, obese), reproductive tract score (RTS: 1, immature, acyclic; 5, mature, cyclic) and temperament score (0, calm; and 1, excited) and fitted with a controlled internal drug release (CIDR, 1.38 g of progesterone) insert for 14 days. Within herd, heifers were randomly assigned either to no‐GnRH group (n = 635) or to GnRH group (n = 676), and heifers in GnRH group received 100 μg of GnRH (gonadorelin hydrochloride, IM) on day 23. All heifers received 25 mg of PGF2α (dinoprost, IM) on day 30 and oestrous detection aids at the same time. Heifers were observed for oestrus thrice daily until AI. Within GnRH groups, heifers were randomly assigned to either AI‐56 or AI‐72 groups. Heifers in AI‐56 group (n = 667) were inseminated at 56 hr (day 32 PM), and heifers in AI‐72 group (n = 644) were inseminated at 72 hr (day 33 AM) after PGF2α administration. All heifers were given 100 μg of GnRH concurrently at the time AI. Controlling for BCS (p < .05), RTS (p < .05), oestrous expression (p < .001), temperament (p < .001) and GnRH treatment by time of insemination (p < .001), the AI‐PR differed between GnRH treatment [GnRH (Yes – 60.9% (412/676) vs. No – 55.1% (350/635); p < .05)] and insemination time [AI‐56 – 54.6% (364/667) vs. AI‐72 – 61.8% (398/644); (p < .01)] groups. The GnRH treatment by AI time interaction influenced AI‐PR (GnRH56 – 61.0% (208/341); GnRH72 – 60.9% (204/335); No‐GnRH56 – 47.9% (156/326); No‐GnRH72 – 62.8% (194/309); p < .001). In conclusion, 14‐day CIDR synchronization protocol for FTAI required inclusion of GnRH on day 23 if inseminations were to be performed at 56 hr after PGF2α in order to achieve greater AI‐PR.  相似文献   

20.
The objective of the study was to evaluate the efficacy of ovarian response and pregnancy rate in anovular buffaloes following Ovsynch and Ovsynch Plus protocols. Buffaloes (n = 55) were divided into two groups: Ovsynch group (n = 26): GnRH (10 μg, GnRH1) on Day 0, PGF2α (25 mg) on Day 7, GnRH (10 μg, GnRH2) on Day 9; Ovsynch Plus group (n = 29): 500 IU equine chorionic gonadotropin (eCG) 72 hr (day ?3) prior to Ovsynch protocol, followed by fixed timed artificial insemination (FTAI) 6 and 24 hr after GnRH2 injection in bot groups. Transrectal ultrasonography was performed daily, that is, from day 0 and ?3 in Ovsynch and Ovsynch Plus group, respectively for ovarian response and pregnancy diagnosis at day 30 post‐insemination. In Ovsynch Plus group, administration of eCG prior to GnRH1 increased (p < .001) the diameter (mm) of dominant follicle (DF) from 10.15 ± 0.26 to 12.23 ± 0.34 within 72 hr of treatment resulting higher ovulatory response to GnRH1. Ovulation after GnRH1 was higher (p < .01) in Ovsynch Plus group (96.6%) than Ovsynch group (61.5%). However, ovulation rate to GnRH2 was similar (p > .05) between groups (Ovsynch group: 76.9% vs. Ovsynch Plus group: 70.0%). Mean DF diameter (mm) that ovulated to both GnRHs was higher (p < .01) than non‐ovulated counterparts in both groups (Ovsynch group: 10.80 ± 0.27 vs. 8.47 ± 0.53; Ovsynch Plus group: 11.99 ± 0.24 vs. 9.5 ± 0.63). Pregnancy was established in buffaloes which responded to both GnRHs, irrespective of groups, being higher (p = .52) in Ovsynch Plus group (34.5%) than Ovsynch group (23.1%), though non‐significant. In summary, this study showed that eCG inclusion prior to Ovsynch regimen improves ovulatory response in anovular buffaloes during low‐breeding season.  相似文献   

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