155 Fertility of sexed semen in Holstein heifers and cows

2020 ◽  
Vol 32 (2) ◽  
pp. 204
Author(s):  
M. Yamaguchi ◽  
M. Takayama ◽  
T. Nishisouzu ◽  
H. López ◽  
O. Dochi

Compared with conventional semen, use of sexed semen decreases the conception rate (CR); therefore, it is important to address the factors that lead to sperm damage. Recently, a novel sexed semen technology was developed for improving dairy cattle fertility (Betthauser et al. 2016 J. Dairy Sci. 99 (E-Suppl. 1), 534). However, there are few reports about the fertility of this novel sexed semen in dairy cattle in Japan. The objective of this study was to compare the CR of traditional sorting semen (S1: flow cytometry/cell sorting) and the novel sexed semen (S2: SexcelTM, ABS Global Inc.) in Holstein heifers and cows in Japan. The CR for the first insemination was obtained from 391 Holstein cows and 148 heifers (10.7-17.8 months old) from 14 dairy farms in Hokkaido from June 2017 to April 2019. Semen used for AI was collected from six bulls and packaged into 0.25-mL straws and frozen. Cows inseminated with conventional frozen semen (S3: unsexed semen in 0.5-mL straws) were used as controls. Calving data were collected from 123 cows and 69 heifers that had calved between January 2018 and May 2019. The diagnosis of pregnancy was confirmed using ultrasonography between 30 and 45 days after insemination. The CR and sex ratio were analysed using chi-square test. The average parity number was 1.9±1.1, and average days open was 84.9±20.4 days. The average interval between calving and the first service was 86.2±20.3 days. The average milk yield (at 305 days) was 12 195±1595 kg. All of the animals were inseminated after the onset of standing heat or removal of the tail chalk of natural heats and oestrus and ovulation synchronisation programmes on the farm. Conception rates of heifers of the first service of S1 (n=54) and S2 (n=94) were 68.5 and 70.2%, respectively. Conception rates of cows of the first service of S1 (n=32), S2 (n=173), and S3 (n=186) were 56.3, 57.8, and 53.8%, respectively. There were no significant differences in CR between these groups (P>0.4). The proportion of female calves produced using S1 (n=61) and S2 (n=57) was 91.8 and 93.0%, respectively, which was significantly more (P<0.01) compared with the 50.0% produced using S3 (n=74). There were no significant differences between S1 and S2 (P>0.8) in terms of the proportion of calves produced. The results of this study demonstrated that the traditional sorting and novel sexed semen (S1 and S2, respectively) did not differ in terms of the first-service CR and produced considerably more female calves than when the conventional semen (S3) was used. Furthermore, these findings indicate that the use of this novel sexed semen could achieve a sex ratio close to 90% female offspring.

2007 ◽  
Vol 19 (1) ◽  
pp. 296
Author(s):  
Y. Heyman ◽  
B. LeGuienne ◽  
C. Audouard ◽  
F. Charreaux ◽  
P. Humblot ◽  
...  

Bulls obtained by somatic cell nuclear transfer (SCNT) have proved to develop normally, produce sperm, and be fertile (Shiga et al. 2005 Theriogenology 64, 334–343; Tecirlioglu et al. 2006 Theriogenology 65, 1783–1799). However, due to epigenetic variability encountered with clones, it cannot be excluded that major alterations may affect the X chromosome and especially the dosage of X inactivation in female embryos. This could result in a deviation of the sex ratio in offspring. To test this hypothesis, the sperm from a cloned bull was used in IVF to assess its ability to induce a different proportion of male and female embryos when compared to results obtained with the sperm of the original donor before cloning. In the present experiment, semen was collected twice weekly during 3 months from a 3-year-old cloned bull of the Charolais breed (H-2) and frozen-stored. Samples from 3 different ejaculates were used in comparison with control frozen straws from the original bull (H-0), prepared at the same age, to produce in vitro embryos. A total of 6 replicate IVF experiments were performed on the same batches of in vitro-matured oocytes (n = 654) using the standard swim-up and IVF technique in the laboratory. Twenty hours after insemination, presumptive zygotes were vortexed and cultured for 7 days in microdrops of B2 medium with Vero cells. Fertilization, cleavage, and blastocyst formation was assessed, and by Day 7, all of the blastocysts were individually frozen after grading. Two groups of 40 representative blastocysts derived from each bull (clone or donor) were used to determine the sex ratio using the sexing kit developed by UNCEIA R&D (Maisons-Alfort, France). Percentages between groups were compared by chi-square test. Semen from the cloned bull resulted in significantly lower fertilization and cleavage rates than that from the original donor (82.7% and 70% vs. 94.6% and 91%, respectively; P < 0.01), but further in vitro development was not different, as the proportions of blastocysts/cleaved were, respectively, 31.5% (74/235) vs. 38.7% (112/290). Sex determination was achieved in 79/80 of the in vitro-produced embryos and indicated that 55% of the blastocysts derived from the clone were male (22/40) and 45% female (18/40). This was not different from the proportion of male (61.5%, 24/39) and female (38.5%, 15/39) embryos in the group derived from semen of the original donor bull. In conclusion, these preliminary results indicate that the semen from this cloned Charolais bull has the same potential for in vitro embryo production as its original cell donor, and there is no evidence that SCNT could induce any deviation of the sex ratio. This observation needs to be confirmed with other sets of cloned bulls. (Shiga et al. 2005 Theriogenology 64, 334–343. Tecirlioglu et al. 2006 Theriogenology 65, 1783–1799.)


2017 ◽  
Vol 3 (2) ◽  
pp. 123
Author(s):  
Dian Novianto ◽  
Budi Nugraha ◽  
Andi Bahtiar

Ikan todak berparuh pendek atau ikan tumbuk atau shortbill spearfish (Tetrapturus angustirostris) merupakan salah satu hasil tangkapan sampingan rawai tuna. Informasi mengenai ikan todak berparuh pendek seperti komposisi ukuran, perbandingan kelamin, dan tingkat kematangan gonadsangat terbatas. Tulisan ini bertujuan untuk menyajikan data dan informasi mengenai aspek biologi ikan todak berparuh pendek yang merupakan hasil tangkapan sampingan dari rawai tuna yang beroperasi di Samudera Hindia. Penelitian ini dilakukan pada bulan September sampai Desember 2008 di perairan Samudera Hindia. Hasil penelitian menunjukan bahwa ikan todak berparuh pendek memiliki kisaran panjang tubuh 135-175 cmLJFL dan modus pada kisaran 155-165 cmLJFL.Perbandingan jenis kelamin ikan jantan dan betina 1:13,5, berdasarkan atas hasil uji chi-square menunjukan bahwa rasio ikan jantan dan betina pada periode penelitian ini tidak seimbang. Pada bulan September ikan todak berparuh pendek betina didominansi oleh tingkat kematangan gonad IIsebesar 66,7%, bulan Oktober oleh tingkat kematangan gonad V sebesar 46,2%, bulan Nopember oleh tingkat kematangan gonad II sebesar 53,3%, sedangkan pada bulan Desember oleh tingkat kematangan gonad III sebesar 42,9%. Pada bulan Nopember sampai Desember terlihat bahwa tingkat kematangan gonad V mulai berkurang, hal ini menunjukan bahwa pada bulan Nopember sampai Desember diduga banyak ikan todak berparuh pendek betina yang sudah memijah. Shortbill Spearfish (Tetrapturus angustirostris) is one of bycatch of tuna longline. Information about shortbill spearfish on the size composition, sex ratio, and maturity stage is still very limited. The objective this paper is to present the data and information about shortbill spearfish which is a bycatch of tuna longline that operated in the Indian Ocean. Research was conducted during September until December 2008 in Indian Ocean. The results showed that the shortbill spearfish have body length about 135-175 cmLJFL and modes in 155-165 cmLJFL. Sex ratio of the male and female was 1:13.5. Based on chi-square test showed that the ratio of male and female in the period of the study was not balanced. In September, the female stage maturity was dominated by level II of 66.7%, October by level V of 46.2%, November by level II of 53.3%, and December by level III of 42.9%. During November until December showed that the maturity stage of level V was decreased, this shows that in this time the female of shortbill spearfish was spawned.


2017 ◽  
Vol 3 (6) ◽  
pp. 363
Author(s):  
Adrian Damora ◽  
Tri Ernawati

Indeks kelimpahan stok ikan beloso (Saurida micropectoralis) di Laut Jawa cenderungmengalami penurunan dari tahun ke tahun dan untuk mencegahnya perlu bahan masukan yang bersumber dari hasil penelitian yang dijadikan sebagai dasar pengelolaannya. Penelitian dilakukan untukmengkaji beberapa aspek biologimeliputi hubungan panjangberat, nisbah kelamin, tingkat kematangan gonad, panjang pertama kali tertangkap dan panjang pertama kali matang gonad, serta kebiasaan makan ikan beloso. Penelitian dilakukan pada bulanApril–Agustus 2009 di perairan utara Jawa Tengah. Hasil penelitian menunjukkan bahwa nisbah kelamin ikan jantan dan betina berada dalam keadaan tidak seimbang. Pertumbuhan ikan beloso bersifat allometrik positif, dimana pertambahan berat lebih cepat dibandingkan pertumbuhan panjangnya dan tingkat kematangan gonad (TKG) ikan beloso didominasi oleh stadium I. Panjang pertama kali ikan beloso tertangkap lebih kecil dari panjang pertama kali matang gonadnya (Lc < Lm) sehingga akan mengancam kelestariaannya. Ikan beloso bersifat karnivora, dimana makanan utamanya adalah potongan ikan dasar, cumi, dan teri. Index of stock abundance of Lizardfish (Saurida micropectoralis) in Java Sea tend to decreased from year to year. The decline was expected because of the potential of Lizardfish decreasing but the effort continue to rise. The objective of this study is to assess the biological aspects including length-weight relationship, sex ratio, gonadal maturity stage, length of first capture (Lc) and length of first mature (Lm), and feeding habit of Lizardfish in north waters of Central Java. This study was conducted from April to August 2009 in north waters of Central Java. Results showed that the sex ratio between males and females was 1:0,97. Based on Chi-square test it is showed that sex ratio is not balanced. The growth of Lizardfish indicated positive allometric where the weight growth more faster than its length growth. The gonadalmaturity stage of Lizard fish is dominated by the first stage. The length of first capture of Lizardfish was under the length of first mature (Lc < Lm) so that will threaten its sustainability. Lizardfish was indicated carnivorous species where its main food are part of demersal fishes, squids and anchovies.


2020 ◽  
Author(s):  
Wei C. Lee ◽  
Hsuan K. Kao ◽  
Mei C. Chen ◽  
Wen E Yang ◽  
Shih M. Chu ◽  
...  

Abstract Background Maintaining the hips in flexion and abduction posture is a common recommendation to facilitate hip maturation in infants. Double diapering helps to maintain a baby’s hips in flexion and abduction posture, but the efficacy of double diapers in hip development has never been verified. We investigated whether double diapering results in greater improvement of the alpha angle in the first months of life. Methods This prospective randomised control study enrolled newborns with Graf type IIa hips. Babies were assigned to the double-diaper or single-diaper group. Parents were instructed on proper hip positioning, except for diapering. Change in the alpha angle from newborn to 1 month after birth, rate of improvement to bilateral Graf type I hips in 1 month, and number of ultrasound examinations and orthopaedic clinic visits in the first year were compared between the two groups. For babies with bilateral IIa hips, we used the averaged data from both hips, and for babies with unilateral IIa hips, we used the data from the IIa hips. Results Seventy newborns with 102 type IIa hips were included from January to December 2017. They were allocated to the double-diaper group (N=33) and single-diaper group (N=37). With a comparable sex ratio, gestational age, and newborn alpha angle, the double-diaper group had a greater increase of alpha angles in 1 month than the single-diaper group (+7.9° vs. +5.2°, t-test, p=0.011). Twenty-eight babies in the double-diaper group (84.8%) and 20 babies in the single-diaper group (54.1%) improved to having bilateral Graf type I hips (chi-square test, p=0.006). Subsequent clinical visits and hip ultrasounds before 1 year were significantly reduced in the double-diaper group. Conclusions Our results support double diapering for enhancing hip maturation in babies with Graf type IIa hips. The amount of improvement may not indicate double diapering as a treatment for hip dysplasia, but its effects in immature hips are noteworthy in reducing further clinical and ultrasound follow-ups.


2010 ◽  
Vol 22 (1) ◽  
pp. 301
Author(s):  
B. G. Moura ◽  
J. Almeida ◽  
F. L. Lima ◽  
G. Balbi ◽  
R. Calmerani ◽  
...  

The aim of the work was to study the effects of year period, technical team, breed, beef cattle and dairy cattle on the pregnancy rates in fresh embryos used in bovine transfer of IVF programs. The study was carried out at the fertilization laboratory In Vitro Nyltta Britto de Carvalho, in partnership with In Vitro Brazil, located at the Boa Vista farm, Barra do Pirai, during August 2007 to September 2008, seeking subsidies to improve the use of the technique in the field. During that period, aspirations and inovulations in 3 different periods I (August to December), II (January to April), and III (May to September) were carried out. The jobs were accomplished by 9 technical teams (A, B, C, D, E, F, G, H, and I) rendering services to the laboratory, by working with 2 beef breeds (Brahman and Nelore) and 3 dairy breeds (Gir, Girolando, and Holstein). The different breed receivers were synchronized, and in general, from 6 to 8 days after heat, they received embryo transfer, the cervical way, under low epidural anesthesia, where each female received 1 fresh embryo of IVF. All cows were submitted to gestation diagnosis by rectal palpation and ultrasonography, in general, 42 days after embryo transfer. The numbers of embryo transferred and pregnancy rates were submitted to the chi-square test, which presented significant differences (P < 0.05). There were pregnancy rates of 36.25%a (n = 960), 39.83%a (n = 1180), and 32.59%b (n = 919) in the I, II, and III periods, respectively. Among the 9 technical teams, there were verified pregnancy rates (%) of 33.51d (n = 1313), 30.30d (n = 330), 35.00cd (n = 405), 39.24cd (n = 1060), 59.25a (n = 7), 33.33d (n = 24), 53.57bc (n = 28), 43.31c (n = 157), and 58.33ab (n = 12) for A, B, C, D, E, F, G, H, and I teams, respectively. Among breeds there were rates (%) of 36.89ab (n = 412), 34.68b (n = 1286), 35.13ab (n = 74), 38.94a (n = 1140), and 37.80ab (n = 82) for Brahman, Nelore, Gir, Girolando, and Holstein, respectively. In the study, pregnancy rates (%) of 35.21b (n = 1698) in beef cattle and 38.65a (n = 1296) in dairy cattle were observed. The differences in pregnancy rates with respect to the evaluated factors, may be explained by individual, breed, and nutritional variations of the animals. There are few data in the literature with results on the embryo transfer use of IVF bovine under field conditions.


2011 ◽  
Vol 23 (1) ◽  
pp. 118 ◽  
Author(s):  
M. Yamaguchi ◽  
M. Tanisawa ◽  
H. Koyama ◽  
S. Takahashi ◽  
O. Dochi

In recent years, reproductive performance of dairy cows has been declining worldwide, especially among cows of high genetic merit for milk production. The cause of the low fertility may considerably vary across countries and is probably multifactorial. This problem remains unsolved. Further, the first-service conception rate of dairy cows has remarkably decreased worldwide. The number of services required for conception has increased due to the low fertility in dairy cows. However, there are few reports about the relationship between conception rates and the number of services in the current dairy cows. The objective of this study was to investigate whether the number of services affects the conception rates of dairy cows. Data concerning the conception rates was obtained for 8386 Holstein cows from 40 commercial dairy herds in eastern Hokkaido, Japan, from 2006 to 2009. The diagnosis of pregnancy was confirmed by rectal palpation between 30 and 45 days after insemination. The average interval between calving and the first-service was 87.3 days. The average milk yield was 8500 kg. Number of conducting services was from the first to the seventh service. The conception rate was analysed using chi-square test. The results are presented in Table1. The conception rate from the first to the seventh service was 40.2 to 54.0%. The conception rate at the first service was significantly low (40.2%); however, the conception rates did not significantly differ after the second-service. A similar tendency was observed during each year. Moreover, the total percentage of conceptions from the first to the third service was 83.8%. The average number of services per conception was 2.2. The results of this study indicate that the first service yielded the lowest conception rates. The conception rates after the second service did not significantly differ. Moreover, ∼84% of the dairy cows became pregnant between the first service and the third service. However, this result shows that ∼16% of the dairy cows in the herds were repeat breeding. In order to improve fertility, it is necessary to study the factors that affect the first-service conception rates of dairy cows. Moreover, to improve the conception rate of dairy cows, it is important to elucidate the cause of these problems. Table 1.The number and percentage of dairy cows conceiving at each of the services for consecutive services


Author(s):  
Obafemi F.A. ◽  
Olabode H.O.K. ◽  
Edeh M.O.

The emergence of the novel Coronavirus Disease in 2019 (COVID-19) in Wuhan, China, and the subsequent global threat, resulting in the current pandemic in over 215 countries, characterized by alarming morbidity, mortality, and social effects in affected humans, as well as an economic downturn due to national and international border closures used as a containment strategy, necessitated this study to assess the opinions of the public on the potential vaccination against COVID-19. This research primarily aims to provide policy makers with useful information on public perceptions of the disease, as well as public knowledge and preparedness for its prevention and eventual eradication. Two hundred (200) organized open-ended questionnaires were distributed at random across the six (6) Area Councils in Abuja, Nigeria. The responses were subjected to the Pearson Chi-Square Test at a CI of 95 % and a level of significance of 5%. Of the 1200 respondents sampled, 976 (81.3%) were willing to be immunized if vaccines were available. However, 5 (0.4%) respondents expressed indifference, while 219 (18.3%) respondents did not support the use of COVID-19 vaccine for a variety of reasons, including a lack of confidence in the vaccine, belief in God for COVID-19 virus safety, and fear and dislike of injectable drugs. Thus, showing a vaccine response that was significantly affected by religion, marital status and education (P<0.05). According to the results of the current study, respondents believe the novel Coronavirus has the potential to cause varying degrees of damage, eventually leading to death. However, their response revealed that vaccine acceptance could be hampered by distrust and other apprehensions. As a result, vaccinations must be implemented strategically and with enough publicity for the intent of enlightenment, empowering citizens to adopt the established intervention mechanism.


2007 ◽  
Vol 19 (1) ◽  
pp. 123 ◽  
Author(s):  
Y. Fukui ◽  
H. Kohno ◽  
T. Togari ◽  
T. Matsuoka ◽  
H. Imai

Artificial insemination, especially with the use of frozen semen, is one of the important tools for embryo transfer program in sheep. The present study investigated the effects of insemination times, breeds, and two inseminators on the fertility of ewes intrauterinally inseminated with frozen–thawed ram semen imported from New Zealand. At 8 sheep farms located in Hokkaido, Japan, during the breeding season (October to December) in 2005, a total of 64 mature (1- to 6-year old) Suffolk (32 heads) and Polled Dorset (32 heads) ewes were used. The ewes were treated with controlled intravaginal drug release (CIDR containing 0.3 g progesterone; Pharmacia &amp; Upjohn, Ltd., Auckland, New Zealand) for 12 days and an injection of 500 IU equine chorionic gonadotropin one day before CIDR removal. The fixed-time intrauterine inseminations (early: 43–46 h; late: 47–50 h) after CIDR removal were performed using the frozen–thawed semen from a Suffolk and Polled Dorset ram by two inseminators. The effects of breeds (Suffolk and Polled Dorset), fixed-time insemination times (early and late phases), and two inseminators on pregnancy (number of pregnant ewes/number of ewes inseminated, 60 days after insemination) and lambing (number of lambed ewes/number of ewes inseminated) rates were analyzed by chi-square test. The prolificacy was compared by Student&apos;s t-test, and differences were also analyzed by Tukey&apos;s omega procedure. The effect of the different farms on fertility was not examined due to the small numbers of ewes per farm. Pregnancy (60.0 and 72.4%, respectively) and lambing (60.0 and 71.4%, respectively) rates were not significantly different between Suffolk and Polled Dorset ewes. The inseminators also did not affect pregnancy (62.6 and 68.8%) and lambing (62.6 and 67.7%) rates. For the insemination times, the lambing rate tended to be higher (P ≤ 0.10) in the early insemination than in the late insemination (76.7% and 53.6%, respectively). The present results show acceptable fertility in ewes inseminated with Suffolk and Polled Dorset frozen semen imported from New Zealand. The early intrauterine insemination (43–46 h after CIDR removal) tended to result in higher fertility than the late insemination (47–50 h after CIDR removal). From 38 lambed ewes, 60 newborn lambs were produced, and this has provided new blood lines of Suffolk and Polled Dorset sheep in Japan.


2011 ◽  
Vol 23 (1) ◽  
pp. 180
Author(s):  
C. A. Zanenga ◽  
C. M. Martins ◽  
N. C. Rodovalho ◽  
F. Aidar ◽  
J. F. Hasler ◽  
...  

Two experiments were conducted to compare conception rates following embryo transfer (ET) of bovine embryos held and transported in Syngro® holding medium (Bioniche, Belleville, Ontario, Canada) with other 2 holding media: Emcare® (ICPbio, Auckland, New Zealand) for in vivo-derived embryos and HEPES-buffered synthetic oviduct fluid (H-SOF) for IVF-derived embryos. The first trial was performed in the period from October through December 2006 at the Curitiba farm in Poços de Caldas, Minas Gerais, Brazil. A total of 140 in vivo-derived embryos were produced from 20 Nelore donor cows and transferred fresh at the same farm. After each donor recovery, embryos were equally separated per stage (morula or blastocyst) and classification (grades 1, 2, and 3) into 2 Petri dishes, each containing either Syngro or Emcare. The embryos were held for an average of 3 h after recovery, loaded into 0.25-mL straws, and transferred fresh into recipients heifers, which were all previously synchronized with the same hormonal protocol treatment and presented a corpus luteum on the day of transference. Conception rate was checked at approximately 60 days of conception by rectal palpation. The chi-square test was used for statistical analysis. The conception rate of embryos maintained in Syngro was significantly higher than those in Emcare: 64.2% (43/67) v. 47.9% (35/73; P < 0.05). A second experiment was performed between September and December 2008 at Embriza Biotechnology Laboratory, Campo Grande, Mato Grosso do Sul, Brazil. A total of 1689 IVF-derived embryos (stage = 7, quality = 1), produced from Nelore donor cows, were randomly assigned to be held and transported in either Syngro (769) or H-SOF transport medium (920). Transportation time ranged from 1 to 9 h, and the recipient farms ranged from 100 to 1200 km in distance from the Embriza Laboratory. Crossbred recipient heifers (Bos taurus × Bos indicus) were synchronized with prostaglandin or vaginal progesterone device protocols. Pregnancy diagnosis was performed by ultrasonography approximately 60 days after ET. Statistical comparisons were performed using the chi-square test. Conception rates resulting from embryos transported in Syngro (45.1%, 347/769) and in H-SOF (42.0%, 386/920) were not different (P = 0.19). Financial support from Embriza Biotecnology, Tecnopec LTDA, and Bioniche Animal Health


2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 281-282
Author(s):  
Nicole N Noga ◽  
Jeremy G Powell ◽  
Brittni P Littlejohn ◽  
Whitney L Rook ◽  
Martin Mussard ◽  
...  

Abstract Preliminary data indicate that shortening the progesterone exposure with CIDR can improve conception rates compared to the established 7-day CO-Synch protocols. The objective was to determine the effects of shortening progesterone exposure from 7 days to 6 days among crossbred beef cows and fixed-time artificial insemination (FTAI) with sex-sorted semen. A total of 147 fall calving (September-November) crossbred beef cows from one location were randomized to one of four treatments: 1 and 4) 7-d CO-Synch + CIDR protocol with administration of gonadotropin-releasing hormone (GnRH) and a CIDR insert on day 0, prostaglandin F2α (PGF) at CIDR removal on day 7, and FTAI occurring 66 h (Treatment 1) or 74 h (Treatment 4) later; 2 and 3) 6-d CO-Synch + CIDR protocol with administration of GnRH and CIDR insert on day 0, prostaglandin F2α (PGF) at CIDR removal on day 6, and FTAI occurring 72 h (Treatment 2) or 80 h (Treatment 3) later. Sex-sorted semen from Angus sires was used for AI. Pregnancy was determined by ultrasound 40 days after AI. Pregnancy rate was analyzed using the MIXED procedure of SAS with CIDR and AI service time as fixed effects. Chi-square analysis was used to assess the number of pregnant and open cows in each treatment using the FREQ procedure of SAS. There was no difference (P = 0.78) in pregnancy rates between 6-d CIDR (0.59 ± 0.05%) and 7 d CIDR (0.57 ± 0.05%) protocols. Cattle bred a shorter period after CIDR removal (0.64 ± 0.05%) had numerically (P = 0.11) greater pregnancy rates compared to those with a longer period after CIDR removal (0.51 ± 0.05%). There was no difference in the number of pregnant and open cows between treatment groups. These data suggest that using a 6-day or 7-day protocol, regardless of breeding time, results in similar conception rates.


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