Artificial Insemination In Cows Research Articles

Effects of a single trace mineral injection at beginning of fixed-time AI treatment regimen on reproductive function and antioxidant response of grazing Nellore cows

Two experiments evaluated the effects of injectable trace minerals (ITM) administered 11 d before artificial insemination (AI) on body weight (BW), body condition score (BCS), ovarian structures, pregnancy rate, and antioxidant response of Nellore cows. In Experiment 1, 20 multiparous cows were assigned to one of two treatments: subcutaneous injection (6 mL/cow; 11 d before AI) of saline solution or ITM (60, 10, 5, and 15 mg/mL of Zn, Mn, Se and Cu, respectively) and BW, BCS, ovarian structures and blood were evaluated. In Experiment 2, 1,144 multiparous cows were assigned to same treatments described in Experiment 1 and pregnancy rate on d 30 was evaluated. In Experiment 1, ITM did not affect (P ≥ 0.23) BW, dominant follicle size, ovulation rate, and plasma concentrations of haptoglobin, ceruloplasmin and progesterone (P4). The ITM treatment tended to increase (P = 0.06) cow BCS and reduce (P ≤ 0.06) corpus luteum (CL) diameter and volume. Furthermore, ITM treatment tended to increase (P = 0.06) plasma concentrations of SOD and increased (P = 0.007) GSH-Px compared with saline injection. In Experiment 2, ITM treatment tended (P = 0.06) to increase pregnancy rate of cows with BCS ≤ 5.0 but not cows with BCS > 5.0 (P = 0.99). The ITM treatment did not alter BW, plasma P4, and acute phase response, but enhanced plasma concentrations of antioxidant enzymes, and tended to enhance BCS and pregnancy rates to AI of cows with BCS ≤ 5.0, even though there was a smaller corpus luteum size.

Effects of a single trace mineral injection on body parameters, ovarian structures, pregnancy rate and components of the innate immune system of grazing Nellore cows synchronized to a fixed-time AI protocol

Two experiments evaluated the effects of injectable trace minerals (ITM) administered 30 d before artificial insemination (AI) on body weight (BW), body condition score (BCS), ovarian structures, pregnancy rate, and components of the innate immune system of grazing Nellore cows. In Exp. 1, 20 multiparous cows (BCS = 4.3 ± 0.4, scale 1 to 9; BW = 388 ± 35 kg) were kept on marandu-grass pasture (Urochloa sp.) and offered free-choice access to a trace mineral supplement. Cows were stratified by BCS and BW and randomly assigned to 1 of 2 treatments: subcutaneous injection (6 mL/cow) of saline solution (0.9% NaCl) or ITM (Multimin 90; containing 60, 10, 5, and 15 mg/mL of Zn, Mn, Se and Cu, respectively) administered 30 d (d -30) before AI (d 0). Pregnancy diagnosis was evaluated on d 30, BW and BCS on d -30, 0 and 30, ovarian structures on d 0 and 14, and blood samples collected on d -30, -26, -22, -17, -11, 0, 7, 14, 21 and 30 for analysis of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), haptoglobin, ceruloplasmin and progesterone (P4). In Exp. 2, 573 multiparous cows (BCS = 4.8 ± 0.5; BW = 400 ± 35 kg) received free-choice access to a trace mineral supplement and were assigned randomly to 1 of 2 treatments (ITM or saline injection 30 d before AI). In Exp. 1, ITM did not affect (P ≥ 0.12) BW, BCS, corpus luteum (CL) diameter and volume, pregnancy rate, and plasma concentrations of haptoglobin, ceruloplasmin and P4 compared to saline injection. Administration of ITM increased (P ≤ 0.008) plasma concentrations of SOD on d -22 and -17 and GSH-Px on d -26 compared to saline. In Exp. 2, ITM tended to increase the pregnancy rate compared to saline injection for cows with BCS < 5 (P = 0.09; 58.4 vs. 46.8 ± 6.5% respectively), but not for cows with BCS > 5 (P = 0.36; 71.8 vs. 67.6 ± 3.5% respectively). Therefore, a single ITM injection 30 d before AI did not alter the body parameters, ovarian structures and acute phase response of grazing Nellore cows, but increased plasma concentrations of antioxidant enzymes, and tended to improve pregnancy rates to AI in cows with BCS < 5.

TECHNOLOGY AUDIT ON DAIRY FARMS

Technological audit of dairy farms in the Novosibirsk region revealed the main problems of keeping, feeding and breeding animals, causing a decrease in production efficiency. Only about 30 % of enterprises with a cow yield of less than 7000 kg per lactation harvest high quality feed. At the same time, on average for three years from 24 to 68 % of the harvested forages were classified as non-class according to the analyzed samples from 15 districts of the region. More than 60 % of the surveyed farms are characterized by poor animal hygiene. Conducted late or not carried out functional hoof trimming. The share of enterprises using only artificial insemination of cows is low, the frequency of gynecological diseases is high. The technology of young growth is not observed. Almost all indicators of such enterprises are significantly different from the reference (with milk yield of cows over 7000 kg). Critical to achieving such productivity are technological discipline, including climate, proper feeding and milking, availability of qualified specialists and herd management system.

The transfer of parthenogenetic embryos following artificial insemination in cows can enhance pregnancy recognition via the secretion of interferon tau.

Repeat breeding is a reproductive disorder in cattle. Embryo transfer following artificial insemination (AI) improves pregnancy rate by replenishing interferon tau (IFNT), but it results in a notably higher rate of twin occurrence. This study hypothesized that parthenogenetic (PA) embryo transfer following AI (AI + PA) could improve the conception rate because that PA embryo become as a supplemental source of IFNT without twins. PA embryos showed higher IFNT mRNA expression than in vitro fertilization (IVF) embryos. An examination of the effect of the cultured conditioned media (CM) of PA or IVF embryos on Madin-Darby bovine kidney cells with stably introduced promoter-reporter constructs of interferon-stimulated gene 15 (ISG15, marker of IFN response) showed higher stimulation levels of ISG15 promoter activity with PA than with IVF embryo. We investigated in vivo the effect of AI + PA on healthy Japanese Black cattle. Cattle transferred with PA embryo alone were non-fertile, but those that underwent AI + PA showed a pregnancy rate of 53.3%, the similar as that with AI alone (60%). In pregnant cattle in AI + PA group, adding the PA embryo upregulated the expression of ISGs and plasma progesterone concentration. No twin were generated in AI only and AI + PA groups. Using repeat breeding Holstein cows that did not become pregnant with 4–9 times of AI, transfer of PA embryo following AI resulted in a higher pregnancy rate than that of control (AI only). We suggest that AI + PA may be beneficial for improving maternal pregnancy recognition in repeat breeder cattle while avoiding twin generation.

Most Common Bulls for Artificial Insemination of Cows and Heifers in a Field of Operation of Veterinary Ambulance Farkasevac

In a field of operation of Veterinary Ambulance Farkasevac farmers are mainly breeding Simmental cattle, followed by the number of Black Holstein and the Red Holstein used for crossing with Simental breed. The selection of bulls for the artificial insemination of cows and heifers in 2014 and 2015 in the field of operation of Veterinary Ambulance Farkasevac shows the interest of the cattle breeders for the bulls that have the best milking index. Such a unilateral selection of bulls for a well-adapted combined Simmental breed points out the shortcomings of selected bulls with a weak index of meat or legs. With such approaches in the second or third generation, the female calves will become good dairy cows, but will have weak legs and reduced longevity. In the case of male calves for fattening, due to poor meat index, such calves will not grow for 15 to 16 months in quality fattening steers, which will ultimately prolong fattening, increase production costs and reduce the quality of meat on slaughter line.

Supplementation with long-acting progesterone in early diestrus in beef cattle: II. Relationships between follicle growth dynamics and luteolysis

The aims were to characterize follicular dynamics in response to supplemental progesterone (P4) and to investigate the relationships between follicular growth and onset of luteolysis in P4-treated cows, submitted or not to artificial insemination (AI). Nonsuckled beef cows detected in estrus were assigned to receive AI or to remain non-AI. Three days after ovulation (ie, D3), AI cows were injected with 150 mg of long-acting P4 (AI + injectable P4 formulation [iP4]; n = 22), and the non-AI cows were assigned to receive 150 mg iP4 (n = 19) or saline (control, n = 19). Between D3 and D21, growth dynamics of the dominant follicles (DFs) was monitored by ultrasonography. Plasma P4 concentrations were measured every other day from D9 to D19. Pregnancy status (ie, P: pregnant and NP: nonpregnant) was examined by ultrasound on D28 to D32. Injectable P4 formulation supplementation decreased average maximum diameter of first-wave DF (DF1). Neither day of emergence of DF2 or DF3 nor the proportion of two- or three-wave cycles were altered by supplemental P4. Daily mean diameter of DF2 and DF3 was also similar between control and iP4 groups. Consistently, daily mean diameter of DF1 in iP4-treated cows was smaller for cows that underwent luteolysis by D15 compared to a later onset. Progesterone concentrations between D9 and D19 decreased earliest in the iP4 group, latest in the control group and was intermediate for the NP-AI + iP4 group. In addition, three-wave cycles presented a delayed decrease on plasma P4 concentrations than two-wave cycles. Further analysis revealed that on two-wave cycles, P4 concentrations on D15 were lowest in the iP4 and NP-AI + iP4 animals compared to the control and P-AI + iP4 groups. Conversely, for three-wave cycles, on D15, P-AI + iP4, NP-AI + iP4, and controls had greater P4 concentrations than the iP4 group. In summary, our data indicate that impairment of first follicular growth was associated with P4-induced shortened luteal lifespan (D14–D15) and that three-wave cycles after AI can be more supportive for pregnancy maintenance in P4-treated cows. We speculate that such conditions play a critical role in the embryonic ability to inhibit iP4-induced early luteolysis reported in part I of this series.

Sex control by Zfy siRNA in the dairy cattle

Zinc-finger Y is located in the short arm of the Y-chromosome and is a highly conserved gene that plays an important role in spermatogenesis. The objective of this study was to investigate the influence of silencing the Zfy gene during spermatogenesis on Y-sperm formation and offspring sex determination in Bos taurus cattle. Three recombinant expression vectors pLL3.7/a, pLL3.7/b and pLL3.7/c were evaluated and only pLL3.7/a effectively silenced the Zfy gene. The pLL3.7/a recombinant expression vector was injected into bull testes, using three injections. Semen was collected and preserved by extending and freezing. The frozen semen was subsequently used in artificial insemination of cows during a breeding season in accordance with the production plan on the farm where the experiment was conducted. Results showed that, after exposure to pLL3.7/a, sperm motility decreased (P < 0.01), but the sperm density was similar (p > 0.05) to the non-treated control semen. Injection of pLL3.7/a resulted in 72.0% female offspring, and was greater than the 49.4% female calves in the control (P ＜ 0.01), Results from this research suggests that the Zfy gene plays a role in the process of Y-sperm formation, and Zfy siRNA is a potential useful approach to control sex of offspring in cattle.

Extending the duration of the voluntary waiting period from 60 to 88 days in cows that received timed artificial insemination after the Double-Ovsynch protocol affected the reproductive performance, herd exit dynamics, and lactation performance of dairy cows

This experiment evaluated the reproductive performance, herd exit dynamics, and lactation performance of dairy cows managed with a voluntary waiting period (VWP) of 60 or 88 d. Secondary objectives were evaluating VWP effect on cyclicity status, uterine health, systemic inflammation, and body condition score (BCS) before first service. Lactating Holstein cows from 3 commercial farms in New York State cows were blocked by parity group and total milk yield in their previous lactation and then randomly assigned to VWP of 60 (VWP60; n = 1,352) or 88 (VWP88; n = 1,359) days in milk (DIM). All cows received the Double-Ovsynch protocol (GnRH-7 d-PGF2α-3 d-GnRH-7 d-GnRH-7 d-PGF2α-56 h-GnRH-16 to 20 h-timed artificial insemination; TAI) for synchronization of ovulation and TAI. For second and greater artificial insemination (AI), cows received AI after detection of estrus or the Ovsynch protocol (GnRH-7 d-PGF2α-56 h-GnRH-16 to 20 h-TAI) initiated 32 ± 3 d after AI for cows not re-inseminated at detected estrus. Cyclicity status (progesterone concentration), uterine health (vaginal discharge and uterine cytology), BCS, and systemic inflammation (haptoglobin concentration) were evaluated at baseline (33 ± 3 DIM for both treatments), beginning of the Double-Ovsynch protocol, and 10 d before TAI. Effects of treatments were assessed with multivariable statistical methods relevant for each outcome variable. Extending duration of VWP from 60 to 88 DIM increased pregnancies per AI (P/AI) to first service (VWP60 = 41%; VWP88 = 47%). Nonetheless, the greatest benefit of extending VWP on first-service P/AI was for primiparous cows (VWP60 = 46%; VWP88 = 55%), as P/AI did not differ within the multiparous cow group (VWP60 = 36%; VWP88 = 40%). Physiological status more conducive to pregnancy-characterized by improved uterine health, greater BCS, reduced systemic inflammation, and to a lesser extent more time to resume ovarian cyclicity-explained the increment in P/AI to first service. Our data also indicated that despite having greater P/AI to first service, cows with the longer VWP had delayed time to pregnancy during lactation (hazard ratio = 0.72; 95% confidence interval 0.69-0.98) and greater risk of leaving the herd, particularly for multiparous cows (hazard ratio = 1.34; 95% confidence interval 1.23-1.47). This shift in pregnancy timing led to an overall extension of the lactation length (+13 d), which resulted in greater total milk yield per lactation (+491 kg) but not greater milk yield per day of lactation. In conclusion, data from this experiment highlight the importance of considering the complex interactions between reproductive performance, herd exit dynamics, and lactation performance as well as the effects of parity at the time of defining the duration of the VWP for lactating dairy cows.

Effects of service number on conception rate in Japanese Black cattle.

The conception rate (CR) of Japanese Black cattle has been decreasing since 1990. The objectives of this study were to compare CR by artificial insemination (AI) number, and to assess the interaction between AI number and possible factors related to CR in Japanese Black cattle. Records of 11,182 AI records for 6,741 heifers and 61,302 AI records for 13,139 cows on 977 farms were analysed. The average CR of heifers was 47.0%, and CR at the first, second and third AI was higher than at the fourth or subsequent AI (p<0.05). The average CR of cows was 47.8%, and their CR at first and second AI was higher than the fourth or subsequent AI (p<0.05). Data analysis with CR as the dependent variable revealed significant interactions of AI number with interval from calving to first AI and AI season. Cows first serviced at ≤48days post-partum had lower CR than those at ≥90days at first AI (p<0.05), but the interval from calving to first AI did not affect CR at second AI. Cows serviced in the autumn had a higher CR at first AI than those serviced in the spring and winter (p<0.05); however, there was no seasonal difference in CR at the second AI. In summary, CR began to decrease from the fourth AI in heifers and the third AI in cows. The AI season and the interval from calving to first AI significantly affected CR only at the first AI.

Fertility of lactating Holstein cows submitted to a Double-Ovsynch protocol and timed artificial insemination versus artificial insemination after synchronization of estrus at a similar day in milk range

Our objective was to compare the AI submission rate and pregnancies per artificial insemination (P/AI) at first service of lactating Holstein cows submitted to a Double-Ovsynch protocol and timed artificial insemination (TAI) versus artificial insemination (AI) to a detected estrus after synchronization of estrus at a similar day in milk range. Lactating Holstein cows were randomly assigned to receive their first TAI after a Double-Ovsynch protocol (DO; n = 294) or to receive their first AI after a synchronized estrus (EST; n = 284). Pregnancy status was determined 33 ± 3 d after insemination and was reconfirmed 63 ± 3 d after insemination. Data were analyzed by ANOVA and logistic regression using the MIXED and GLIMMIX procedures of SAS (SAS Institute Inc., Cary, NC). By design, days in milk at first insemination did not differ between treatments (76.9 ± 0.2 vs. 76.7 ± 0.3 for DO vs. EST cows, respectively), but more DO cows were inseminated within 7 d after the end of the voluntary waiting period than EST cows (100.0 vs. 77.5%). Overall, DO cows had more P/AI than EST cows at both 33 d (49.0 vs. 38.6%) and 63 d (44.6 vs. 36.4%) after insemination, but pregnancy loss from 33 to 63 d after insemination did not differ between treatments. Primiparous cows had more P/AI than multiparous cows 33 and 63 d after insemination, but the treatment by parity interaction was not significant. Synchronization rate to the hormonal protocols was 85.3%, which did not differ between treatments; however, synchronized DO cows had more P/AI 33 d after insemination than synchronized EST cows (54.7 vs. 44.5%). In summary, submission of lactating Holstein cows to a Double-Ovsynch protocol and TAI for first insemination increased the percentage of cows inseminated within 7 d after the end of the voluntary waiting period and increased P/AI at 33 and 63 d after first insemination resulting in 64 and 58% more pregnant cows, respectively, than submission of cows for first AI after detection of estrus at a similar day in milk range. We conclude that, because the proportion of synchronized cows did not differ between treatments, DO cows had more P/AI than EST cows because of an intrinsic increase in fertility after submission to a fertility program.

13 EFFECTS OF NERVE GROWTH FACTOR-β, PURIFIED FROM BULL SEMINAL PLASMA, ON CORPUS LUTEUM FUNCTION AND CONCEPTUS DEVELOPMENT IN COWS

Nerve growth factor-β (NGF) has been identified in the seminal plasma of livestock and is required for the induction of ovulation in camelids. Until recently, it was thought to play a negligible role in species with spontaneous ovulation. On the contrary, recent studies have shown that systemic administration of NGF, purified from llama seminal plasma, was associated with larger corpus luteum (CL) diameter and higher concentrations of progesterone (P) following ovulation. The objective of the current project was to determine if systemic administration of NGF, purified from bovine seminal plasma, would improve CL formation and enhance embryonic development. Our hypothesis was that systemic administration of NGF at the time of artificial insemination in cows would lead to increased CL volume, increased P secretion, and improved expression of markers of conceptus development and maternal recognition of pregnancy. Seminal plasma was harvested from semen collected by electroejaculation in Angus cross bulls. Purification of NGF was performed using a combination of anion- and cation-exchange chromatography and gradient elution. Beef cows were randomly assigned to CONT (n = 30) or NGF (n = 30) groups and synchronized using a 7-day Co-Synch + CIDR program. At time of insemination (day 0), NGF cows received 296 µg of purified NGF, reconstituted in 12 mL of PBS, and CONT cows received 12 mL of PBS intramuscularly. Blood samples were collected from the coccygeal vein of each cow at days 0, 3, 7, 10, 14, 19, 21, 28, 31, 38, 45, and 66. Ultrasound was performed at each time point for determination of ovarian structures (day 0), corpus luteum volume (all time points), and fetus detection (day 28). Statistical analysis was performed using analysis of variance with repeated-measures in R (R version 3.2.2; https://www.r-project.org/). At day 28, 17/30 (57%) CONT cows and 21/30 (70%) NGF cows were diagnosed as pregnant (P = 0.15). At day 0, cows that later became pregnant had a larger follicular diameter (1.46 cm) than those diagnosed as open (1.16 cm; P &lt; 0.01). Follicular diameter at day 0 did not differ significantly between CONT and NGF groups for either open (P = 0.35) or pregnant (P = 0.90) cows. CL volume in open cows was affected by day (P &lt; 0.001) with no treatment (P = 0.84) or treatment by day (P = 0.42) interaction. CL volume in pregnant cows was affected by both day (P &lt; 0.001) and treatment (P &lt; 0.001), with CONT cows having a higher CL volume than NGF cows. Though NGF appeared to have an inhibitory effect on CL volume in pregnant cows, results are still pending for quantification of P, insulin-like growth factor 1, pregnancy-specific protein B, and interferon-stimulated genes, which will more accurately assess the effects that NGF may have on conceptus development. The results of this study will help us to better understand the role of the seminal plasma protein, NGF, at ovulation and determine if it can be utilised to enhance insemination programs in cattle.

Split-time artificial insemination in beef cattle: I–Using estrous response to determine the optimal time(s) at which to administer GnRH in beef heifers and postpartum cows

Two experiments evaluated timing of GnRH administration in beef heifers and cows on the basis of estrous status during split-time artificial insemination (AI) after controlled internal drug release (CIDR) based protocols. In experiment 1, estrus was synchronized for 816 pubertal and prepubertal or peripubertal heifers using the 14-day CIDR-PGF2α (PG) protocol, and in experiment 2, estrus was synchronized for 622 lactating cows using the 7-day CO-Synch + CIDR protocol. For both experiments, estrus detection aids (Estrotect) were applied at PG, with estrus recorded at 66 and 90 hours after PG. Treatments were balanced across locations for heifers using reproductive tract score and weight; whereas for cows, treatments were assigned and balanced to treatment according to age, body condition score, and days postpartum. Timing of AI for heifers and cows was on the basis of estrus expression 66 hours after PG. Females in each treatment that exhibited estrus before 66 hours were inseminated at 66 hours, whereas AI was delayed 24 hours until 90 hours after PG for females failing to exhibit estrus before 66 hours. Females in treatment one received GnRH 66 hours after PG irrespective of estrus expression; however, in treatment 2, GnRH was administered coincident with delayed AI only to females not detected in estrus at 66 hours after PG. Among heifers, there was no effect of treatment on overall estrous response (P = 0.49) or AI pregnancy rate (P = 0.54). Pregnancy rate for heifers inseminated at 66 hours was not influenced by GnRH (P = 0.65), and there were no differences between treatments in estrous response during the 24 hours delay period (P = 0.22). Cows in treatment 2 had a greater (P = 0.04) estrous response during the 24-hour delay period resulting in a greater overall estrous response (P = 0.04), but this did not affect AI pregnancy rate at 90 hours (P = 0.51) or total AI pregnancy rate (P = 0.89). Pregnancy rate resulting from AI for cows inseminated at 66 hours was not influenced by GnRH (P = 0.50). In summary, when split-time AI was used with the 14-day CIDR-PG protocol in heifers or the 7-day CO-Synch + CIDR protocol in cows, administration of GnRH at AI to females that exhibited estrus before 66 hours after PG was not necessary. Furthermore, among heifers for which AI was delayed on the basis of failure to exhibit estrus before 66 hours after PG, timing of GnRH (66 vs. 90 hours after PG) was more flexible. Delayed administration of GnRH to 90 hours after PG coincident with AI for cows that failed to exhibit estrus before 66 hours improved overall estrous response; however, in this study, a corresponding increase in pregnancy rate resulting from AI was not observed.

Uterine lavage is efficient to recover endometrial cytology sample and does not interfere with fertility rate after artificial insemination in cows

Productivity rates directly depend on the fertility of a herd, which in turn can be influenced by many factors. Semen deposited in the female reproductive tract is foreign to the body and, in response to this invasion, produces an inflammatory reaction, which is characterized by rapid infusion of polymorphonuclear (PMN) cells. Techniques to obtain an endometrial sample are usually invasive and can mask the true inflammatory response. Ultrasound is a noninvasive technique and can contribute to the diagnosis of postartificial insemination (AI) inflammatory response in cattle. The present study was divided into two experiments. The aim of experiment 1 was to compare two methods of endometrial cytology collection, uterine cytobrush (UC) and uterine lavage (UL), and their effects on uterine hemodynamics that provide information about blood flow. The two methods were evaluated by Doppler ultrasound using the spectral and color modes. For that purpose, 19 Nellore cows were synchronized for timed AI and subjected to UC (n = 9) or UL (n = 10). The techniques were performed 4 hours after AI. The results showed that both techniques allow collection of a good quality sample and with enough PMN cells to perform counting. More PMN cells were obtained by UL than UC. There was no difference in uterine blood flow between the UC and UL groups in any of the periods evaluated (34 hours before and 4, 24, and 48 hours after collection of uterine sample). On the basis of results of experiment 1, the effect of UL on fertility was studied in experiment 2. A total of 128 Nellore cows were synchronized for TAI; 35 cows were subjected to endometrial cytology by UL 4 hours after AI, and 93 were not submitted to any procedure (control). Pregnancy diagnosis was performed by transrectal ultrasound 30 days after AI. Pregnancy rates did not differ between UL (54.29%) and control (56.99%) groups. The results of this study showed that UL allows the collection of more representative cells of the surface of the uterus than UC technique and causes no damage to the reproductive tract. Moreover, UL did not affect pregnancy rate when performed 4 hours after AI.

Effects of semen sexing kits (Heiferplus&lt;sup&gt;TM&lt;/sup&gt; and Bullplus&lt;sup&gt;TM&lt;/sup&gt;) supplemented to frozen-thawed bull semen on pregnancy rates, foetal sex ratios and selected reproductive parameters in cows

It has been claimed that artificial insemination (AI) of cows with frozen-thawed semen treated with commercially produced kits, HeiferplusTM (HP, in favour of female gender) and BullplusTM (BP, in favour of male gender), increases the birth chance of calves with desired sex ratio by at least 20-25% and pregnancy rates by at least 5-20%. Hence, this study was conducted to investigate the efficacy of HP and BP kits as combined with AI on the pregnancy rates, foetal sex ratios and some reproductive parameters in cows. For this, a total of 200 cows (100 Holsteins and 100 Simmentals) from three to five years old were used. Fifty Holstein and 50 Simmental cows served as controls. The other half of Holstein and Simmental cows was artificially inseminated with frozen-thawed semen treated with HP and BP, respectively. Findings showed that the AI of cows with frozen-thawed semen treated with HP had no significant effect on the pregnancy rate [52.0% (26/50) in HP group; 56.0% (28/50) in control group], female calf ratio [52.0% (13/25) in HP group; 44.4% (12/27) in control group], embryonic death, abortion, stillbirth, twinning and gestation length as compared to the control group. Similarly, AI of cows with frozen-thawed semen treated with BP did not lead to any significant effect on the pregnancy rate [64.0% (32/50) in BP group; 58.0% (29/50) in control group], male calf ratio [53.1% (17/32) in BP group; 39.3% (11/28) in control group] and other reproductive parameters as compared to the control group. In conclusion, HP and BP treatments of semen used in the AI provided only slight, non-significant increases in female (7.6%) and male (13.8%) calf ratios, respectively.

Effect of different gonadorelin (GnRH) products used for the first or resynchronized timed artificial insemination on pregnancy rates in postpartum dairy cows

Different GnRH products are used for timed artificial insemination (AI) in postpartum dairy cows. Previous studies reported greater LH release and increased ovulation percentage for gonadorelin diacetate tetrahydrate compared with gonadorelin hydrochloride but pregnancies per AI (P/AI) were not evaluated. The objective, therefore, was to compare P/AI for cows treated with either gonadorelin hydrochloride or gonadorelin diacetate tetrahydrate before the first timed AI or resynchronized timed AI. Holstein cows (n = 3938) in a confinement dairy in northeast Missouri were assigned to weekly cohorts (n = 22) on the basis of calving date. Cows were treated with “Presynch Ovsynch” (PGF2α, 14 days; PGF2α, 14 days; GnRH, 7 days; PGF2α, 56 hours; GnRH, 16 hours; timed AI) so that the first timed AI was 70 to 76 days postpartum. The PGF2α was Lutalyse (5 mL; 25 mg; Zoetis). The GnRH product was either gonadorelin hydrochloride (2 mL; 100 μg; n = 1945) or gonadorelin diacetate tetrahydrate (2 mL; 100 μg; n = 1993) and alternated weekly for cows assigned to cohorts. There were first timed AI (n = 1790) and resynchronized timed AI (n = 2148) cows within each cohort. The resynchronization began 32 days after timed AI (GnRH, 6 days; ultrasound pregnancy diagnosis, 1 day; and then for nonpregnant cows: PGF2α, 56 hours; GnRH, 16 hours; timed AI). The trial was conducted from January to February 2012 (n = 1203) and July to October 2012 (n = 2735). Cows were fed a total mixed ration, milked thrice daily, and milk tested monthly for volume, somatic cell count (SCC), fat percentage, protein percentage, and milk urea nitrogen. Data were analyzed by fitting the binary response data to a generalized linear mixed model for repeated measures. There was no effect of the GnRH product (treatment) on P/AI (38.4 ± 1.2 vs. 35.7 ± 1.3; gonadorelin diacetate tetrahydrate vs. gonadorelin hydrochloride). Treatment interactions with parity, month of breeding, or insemination number were not significant. The first-service P/AI (38.8 ± 1.4%) was greater (P < 0.05) than the resynchronized P/AI (35.3 ± 1.3%). Cows inseminated in the summer had lesser P/AI (effect of month; P < 0.001) compared with cows inseminated in the winter. There was a decrease (P < 0.002) in timed AI conception for cows with a greater milk SCC and an increase (P < 0.003) in P/AI for cows with a greater milk protein percentage. In conclusion, the GnRH product did not affect P/AI for the first or resynchronized timed AI in an Ovsynch-based program. Other factors affected P/AI including service number (lesser for the second service or greater), month (lesser in summer months), SCC (lesser for cows with greater SCC), and milk protein percentage (greater for cows with greater protein percentage).

LEP gene allelic polymorphism in a subpopulation of Ayrshire cattle

Genotyping of the leptin gene locus (LEP) (SNP: R25C, Y7F, and A80V) has been conducted in cows from two cattle droves (n = 106 and n = 34) and in bulls of Ayrshire cattle (n = 9) that are intensively used at present for artificial insemination in cows in Krasnodar krai. The absence of A80V polymorphism (C --> T at position 95691973 bp of leptin gene) has been established in the genotypes of Ayrshire cattle as compared to Holstein cattle; however, the F allele (Y7F site A --> T at position 95689996 bp of LEP gene), which is rare in Holstein cattle, was shown to be frequent in Ayrshire cows and producer bulls (with a frequency of 0.22-0.79). The heterozygosity did not exceed 0.11 in adult animals, which might be evidence of a decreased vitality in animals bearing the FF genotype. Moreover, the CC genotype (R25C site T-C at position 95690050 bp of LEP gene) was revealed to be linked to the YY genotype (Y7F site) in 97% of cases from possible combinations of the CCYY, CCYF, and CCFF genotypes, while the FF genotype (Y7F site) was observed to be linked to the RR genotype (R25C site) in 100% of cases of possible combinations of FFCC, FFRC, and FFRR genotypes.

Comparison of fertility, regular returns-to-estrus, and calving interval between Ovsynch and CO-synch + CIDR protocols in dairy cows

The main aims of the present study were to compare the pregnancy rate (PR), regular returns-to-estrus, and calving interval of a CO-Synch + controlled internal drug release (CIDR) device, commonly used to synchronize ovulations in beef cows, with the classical Ovsynch protocol in high-producing dairy cows. Holstein-Friesian cows (n = 128) from six commercial dairy herds, ≥40 days postpartum and not previously inseminated, were randomly assigned to one of two treatments. Cows submitted to Ovsynch protocol (group OS as control group; n = 66) received 10 μg of a GnRH analogue 7 days before and 48 hours after 25 mg PGF2α, followed by artificial insemination (AI) 16 hours after the second GnRH administration. Cows submitted to CO-Synch + CIDR (1.38 g of progesterone) inserted for 7 days beginning at the first GnRH administration (group CoS + CD; n = 62) had the second administration of GnRH concurrent with AI, 64 hours after CIDR removal/PGF2α administration. Nonpregnant cows with return-to-estrus between 18 and 24 days after first AI were reinseminated (second AI). Logistic regressions were used to analyze PR and returns-to-estrus. No effect of group or herd was observed in PR at first timed AI. However, the sum of cows pregnant at first AI and nonpregnant cows with regular returns-to-estrus and the total PR (first + second AI) were influenced by group treatment. Overall, cows of group CoS + CD (total PR = 56.5%) were 2.1 times more likely to became pregnant after AI and until first regular returns-to-estrus than cows of group OS. The calving interval was lower in group CoS + CD (425.9 ± 78.8 days; ±SD) than in group OS (475.3 ± 83.7 days). The CO-Synch + CIDR protocol was reliable to use in dairy herds and provided reproductive advantages when compared with Ovsynch protocol.

Effect of early or late resynchronization based on different methods of pregnancy diagnosis on reproductive performance of dairy cows

The aim of this study was to compare the reproductive performance of dairy cows subjected to early (ER) or late (LR) resynchronization programs after nonpregnancy diagnoses based on either pregnancy-associated glycoproteins (PAG) ELISA or transrectal palpation, respectively. In addition, the accuracy of the PAG ELISA for early pregnancy diagnosis was assessed. Lactating Holstein cows were subjected to a Presynch-Ovsynch protocol with timed artificial insemination (AI) performed between 61 and 74 DIM. On the day of the first postpartum AI, 1,093 cows were blocked by parity and assigned randomly to treatments; however, because of attrition, 452 ER and 520 LR cows were considered for the statistical analyses. After the first postpartum AI, cows were observed daily for signs of estrus and inseminated on the same day of detected estrus. Cows from ER that were not reinseminated in estrus received the first GnRH injection of the Ovsynch protocol for resynchronization 2d before pregnancy diagnosis. On d 28 after the previous AI (d 27 to 34), pregnancy status was determined by PAG ELISA, and nonpregnant cows continued on the Ovsynch protocol for reinsemination. Pregnant cows had pregnancy status reconfirmed on d 46 after AI (d 35 to 52) by transrectal palpation, and those that lost the pregnancies were resynchronized. Cows assigned to LR had pregnancy diagnosed by transrectal palpation on d 46 after AI (d 35 to 52) and nonpregnant cows were resynchronized with the Ovsynch protocol. Blood was sampled on d 28 after AI (d 27 to 34) from cows in both treatments that had not been reinseminated on estrus and again on d 46 after AI (d 35 to 52) for assessment of PAG ELISA to determine the accuracy of the test. Cows were subjected to treatments for 72d after the first insemination. Pregnancy per AI (P/AI) at first postpartum timed AI did not differ between treatments and averaged 28.9%. The proportion of nonpregnant cows that were resynchronized and received timed AI was greater for ER than for LR (30.0 vs. 7.6%). Cows in ER had a shorter interval between inseminations when inseminated following spontaneous estrus (21.7±1.1 vs. 27.8±0.8d) or after timed AI (35.3±1.2 vs. 55.2±1.4d). Nevertheless, the ER did not affect the rate of pregnancy (adjusted hazard ratio=1.23; 95% confidence interval=0.94 to 1.61) or the median days postpartum to pregnancy (ER=132 vs. LR=140). A total of 2,129 PAG ELISA were evaluated. Overall, sensitivity, specificity, and positive and negative predictive values averaged 95.1, 89.0, 90.1, and 94.5%, respectively, and the accuracy was 92.1%. In conclusion, PAG ELISA for early diagnosis of pregnancy had acceptable accuracy, but early resynchronization after nonpregnancy diagnosis with PAG ELISA did not improve the rate of pregnancy or reduce days open in dairy cows continuously observed for estrus.

Ovulation timing and conception risk after automated activity monitoring in lactating dairy cows

Using 1 market-available activity monitor, 3 experiments were conducted in dairy cows to determine timing of ovulation, compare within-herd conception risk of cows inseminated based on activity monitors versus timed artificial insemination (AI), and determine conception risk of cows inseminated at various intervals after achieving an activity threshold. In experiment 1, ovaries were scanned every 3h by transrectal ultrasonography to determine the time of ovulation beginning 14±0.5h after the achieved activity threshold (n=132) or first standing event (n=59), or both (n=59). Progesterone at the first ovarian scan (0.1±0.01ng/mL) and ovarian structures [1 or 2 preovulatory-sized follicles (16.5±0.2mm)] confirmed that 88.6% of cows identified by activity were in estrus. The remaining 15 cows (11.4%) with a corpus luteum and elevated progesterone concentration (5.3±0.5ng/mL) were classified as false positives. The average interval from first standing event to ovulation (n=59) differed slightly from the interval after the achieved threshold (26.4±0.7 vs. 24.6±0.7h, respectively). In 97 cows fitted with activity monitors, that interval was 25.7±0.4h. In experiment 2, the conception risk in 394 cows in 1 herd fitted with activity monitors was compared with that of 413 cows submitted to a timed AI program through 3 AI services. Days to first AI were reduced in cows fitted with activity monitors, and conception risk after activity threshold was less than that for timed AI at first service because of differing days in milk at first AI. Both median and mean days to pregnancy, however, were reduced in activity-group cows by 10 and 24d, respectively, compared with timed AI cows. In experiment 3, 4,019 cows in 19 herds were inseminated after achieving the activity threshold. Conception risk was determined for cows inseminated at various intervals after the achieved activity threshold. A curvilinear conception risk curve peaked at 47.9% for primiparous cows inseminated between 13 and 16h, whereas conception risk in multiparous cows was steady at 34% through 12h and decreased thereafter. These experiments demonstrate that time of ovulation after activity threshold closely resembles the time of ovulation after first standing estrus. Time of insemination up to 12h after the activity threshold produced similar conception risks for multiparous cows, whereas intervals shorter than 13 and greater than 16h in primiparous cows seemed to compromise their conception risk. Although conception risk may not be improved at individual inseminations after achieving an activity threshold, the rate of achieving pregnancy is hastened. Activity monitors can accurately predict ovulation and time of AI.

Reproductive performance of lactating dairy cows managed for first service using timed artificial insemination with or without detection of estrus using an activity-monitoring system

Lactating dairy cows (n=1,025) on a commercial dairy farm were randomly assigned at 10±3d in milk (DIM) to 1 of 3 treatments for submitting cows to first artificial insemination (AI) and were fitted with activity-monitoring tags (Heatime; SCR Engineers Ltd., Netanya, Israel) at 24±3 DIM. Cows (n=339) in treatment 1 were inseminated based on increased activity from the end of the voluntary waiting period (50 DIM) until submission to an Ovsynch protocol; cows without increased activity from 21 to 65 DIM began an Ovsynch protocol at 65±3 DIM, whereas cows without increased activity from 21 to 50 DIM but not from 51 to 79 DIM began an Ovsynch protocol at 79±3 DIM. Cows (n=340) in treatment 2 were inseminated based on activity after the second PGF2α injection of a Presynch-Ovsynch protocol at 50 DIM, and cows without increased activity began an Ovsynch protocol at 65±3 DIM. Cows (n=346) in treatment 3 were monitored for activity after the second PGF2α injection of a Presynch-Ovsynch protocol, but all cows received timed AI (TAI) at 75±3 DIM after completing the Presynch-Ovsynch protocol. The activity-monitoring system detected increased activity in 56, 69, and 70% of cows in treatments 1, 2, and 3, respectively. Treatment-2 cows had the fewest average days to first AI (62.5), treatment-3 cows had the most average days to first AI (74.9), and treatment-1 cows had intermediate average days to first AI (67.4). Treatment-1 and -2 cows in which inseminations occurred as a combination between increased activity and TAI had fewer overall pregnancies per AI (P/AI) 35d after AI (32% for both treatments) compared with treatment-3 cows, all of which received TAI after completing the Presynch-Ovsynch protocol (40%). Based on survival analysis, although the rate at which cows were inseminated differed among treatments, treatment did not affect the proportion of cows pregnant by 300 DIM. Thus, use of an activity-monitoring system to inseminate cows based on activity reduced days to first AI, whereas cows receiving 100% TAI after completing a Presynch-Ovsynch protocol had more P/AI. The trade-off between AI service rate and P/AI in the rate at which cows became pregnant was supported by an economic analysis in which the net present value ($/cow per year) differed by only $4 to $8 among treatments. We conclude that a variety of strategies using a combination of AI based on increased activity using an activity-monitoring system and synchronization of ovulation and TAI can be used to submit cows for first AI.