Artificial Insemination Group Research Articles

261 Vitamin A administration in pregnant cows or newborn calves: Growth performance and carcass traits

Abstract This study aimed to evaluate the effects of Vitamin A (VA) injection on the growth performance and carcass traits of Nellore × Angus crossbred steers and heifers. For that, the same sire inseminated Nellore cows from two artificial insemination (AI) groups were randomly assigned to one of three treatments at 250 d of gestation: no VA injection (Control); VA injection in pregnant cows at 250 d of gestation (VAcow; 2,000,000 IU single dose); VA injection in newborn calves at birth and 60 d of age (VAcalf; 200,000 IU each dose). Cow-calf pairs were kept in the same paddock, and calves received creep-feeding supplementation from 90 d of age to weaning. After weaning, steers and heifers [n = 36; body weight (BW) 213 ± 25.7 kg] were stratified by treatment and BW and allotted into 16 pens. After 207 d of feeding (77 d of growing diet + 130 d of finishing diet), steers and heifers were slaughtered at a commercial abattoir. Data were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of VA injection, sex, and VA injection*sex interaction. The random effects were animal, AI group, and cow parity. Average daily gain before weaning (P < 0.01) and final BW in the finishing phase were greater (P = 0.04) in VAcow steers compared with heifers from all treatments (Table 1). Vitamin A had a positive impact on weaning BW of male calves and a negative impact on heifers (P < 0.01). There was no treatment difference (P = 0.35) in feedlot average daily gain (ADG), but steers had greater (P = 0.03) ADG compared with heifers. Moreover, VAcow steers had greater dry matter intake (DMI) in the feedlot (P = 0.04) compared with other treatments, and there was no effect of VA on DMI of heifers. On the other hand, feedlot feed efficiency tended to be greater (P = 0.07) in Control steers compared with other treatments, with no VA effect on heifers too. The ribeye area was greater (P = 0.04) in VAcow steers than in Control steers and heifers from all treatments. Intramuscular fat content was greater (P = 0.04) in VAcow steers than in Control and VAcalf steers. However, there was no effect of VA on heifers and VAcow steers. In addition, VAcow treatment tended (P = 0.08) to increase backfat thickness. In conclusion, VA injection in pregnant cows can be a strategy to improve marbling in steers, but there is no effect on intramuscular fat in heifers. Additionally, VA injection in pregnant cows produced intramuscular content in beef of steers, similar to heifers.

Is prolonged luteal phase a problem in lactating Holstein cows?

In this study, the main objective was to assess if long luteal phases could have other causes than pregnancy losses. We enrolled Holstein dairy cows ≥50 d in milk (DIM) from a commercial herd in Brazil from October 2016 to August 2017. All cows received an estradiol-based synchronization protocol, and, on the day of insemination (d 0), were randomly assigned either an artificial insemination (AI) or a placebo insemination (PBO) in a 3:1 ratio. An ultrasound was used to assess the presence of a CL on d17, 24, and 31, which, combined to the information from patches for the detection of estrus, was used to determine the length of the luteal phase following AI or PBO. Pregnancy was assessed by ultrasound on d 31 and cows that were pregnant were excluded from the analyses. The length of the estrous cycles was categorized as short (<17 d), normal (17-23 d), long (24-30 d), and very long (≥31 d). We compared the proportion of cows in each category between the AI and PBO groups using a cumulative ordinal mixed model. We define prolonged luteal phase as estrous cycles ≥24 d and tested its association with potential risk factors (parity, season, DIM, uterine size and position score, milk production, body condition score, and the presence of a corpus luteum (CL) at enrollment to the synchronization protocol) using mixed logistic regression models. Results are presented as odds ratio (OR) and 95% credible intervals (BCI). Data from 876 inseminations (AI: n = 616, PBO: n = 260) was collected. Overall, 12% of estrous cycles were short, 31% were normal, 19% were long, and 38% were very long. There was no difference in the odds of being in longer estrous cycle categories for the AI compared with the PBO group (OR = 0.92, 95% BCI = 0.76-1.10). Season and presence of a CL at enrollment were associated with prolonged luteal phase. In the AI group, there was a possible effect of early pregnancy losses on the lifespan of the CL, but not the PBO group, which led us to conclude that long and very long estrous cycles were not all caused by the embryonic loss. In fact, the high prevalence of cows with an extended CL lifespan in the present study suggests this could be an under- or miss-reported characteristic of high-producing lactating Holstein cows. This finding may have important repercussions in the understanding of the CL function physiology of lactating Holstein cows.

The primipara reproductive performance of Bali cows with natural mating compared to artificial insemination

This study was conducted to observe Bali cows’ primipara reproductive performance between natural mating and artificial insemination. Fifty Bali cows owned by 44 farmers in Central Lombok Regency, West Nusa Tenggara Province, were used as the research sample at the first mating; 19 cows were subjected to natural mating (NM) and 31 cows to artificial insemination (AI). Farmer’s profile data, rearing system, and reproductive performance (the age of puberty, the first mating, gestation period, postpartum estrus, postpartum mating, and calving interval) were obtained from the farmer’s interview and inseminator record. An independent sample t-test was performed to analyze the differences in reproductive performance between NM and AI groups. The results showed that there were significant differences (P<0.05) in postpartum estrus (48.94 ± 12.75 vs. 82.74 ± 26.51 days), postpartum mating (59.00 ± 14.00 vs. 85.64 ± 25.45 days), and calving interval (348.57 ± 18.20 vs. 393.19 ± 31.05 days). In conclusion, Bali cows’ reproductive performance in primipara with natural mating is better than artificial insemination. So recommended that for the first mating, it is better to have a natural mating.

Differences in hormone levels around parturition in Hanwoo cattle (Bos taurus coreanae) following artificial insemination and embryo transfer.

BackgroundWith unique genetic traits, Hanwoo cattle (Bos taurus coreanae) are well‐adapted to the Korean environment. However, their perinatal mortality rate is 2%–3%, which imposes an economic burden.ObjectiveDue to insufficient data on hormonal changes around parturition, the timing of parturition is often predicted subjectively; few studies have examined hormones in Hanwoo cattle. We measured the changes in various hormones around parturition, to seek an objective predictor of parturition time.MethodsIn 14 female Hanwoo cattle, we measured progesterone, prolactin and cortisol concentrations daily in jugular vein blood samples, beginning 6 days before parturition until 7 days after parturition. Conception was induced in five animals using artificial insemination. Nine animals received embryo transfer.ResultsDuring parturition, the concentration of progesterone decreased significantly in the embryo transfer group (n = 9) and in the total population (n = 14); it did not change significantly in the artificial insemination group (n = 5). Prolactin concentration increased on the day of parturition but did not differ significantly among the groups. Cortisol remained constant throughout the study course.ConclusionWe concluded that parturition time can be predicted in Hanwoo cattle using progesterone concentration. This knowledge can reduce perinatal mortality, which would help to improve farm income and animal welfare.

Consequences of nescient mating: Artificial insemination increases cub rejection in the giant panda (Ailuropoda melanoleuca)

Artificial insemination (AI) is a valuable tool for conservation breeding programs as it can promote reproductive success and genetic diversity in species with decreasing populations. However, females that undergo AI do not experience natural mating events, which we term, “nescient mating.” Thus, these females would not be able to assess the quality of their mate through physical, olfactory, or visual cues. Previous research has found that AI can lead to diminished breeding outcomes when compared to natural mating. In this study, we investigated whether fertilization method (natural mating versus AI) affects postpartum behaviors, such as cub rejection and maternal care in female giant pandas. We analyzed data from 202 cubs and 43 mother-cub dyads between 1996 and 2018. We did not find a difference in gestation length, cub weight, or cub survivorship between naturally mated and artificially inseminated females. Compared to naturally inseminated females, artificially mated females were significantly more likely to reject cubs (p = 0.039). Contrary to what we had predicted, maternal care and infant behaviors during the first month did not differ between natural mating and AI groups. Taken together, our results indicate that female giant pandas who experienced nescient mating may have reduced offspring investment, manifest in increased cub rejection. However, the lack of behavioral differences between AI and natural mating groups was encouraging, indicating that once a female accepted a cub to rear, maternal care was adequate to ensure cub survival. Nonetheless, we recommend that conservation breeding programs prioritize natural mating as higher rates of maternal rejection increase the facility and human time cost of cub rearing and also the chances of detrimental downstream effects on offspring adult behaviors in the giant panda.

Growth analysis and blood profile in piglets born by embryo transfer

Assisted reproductive technologies (ART), besides solving several reproductive problems, it has also been used as a tool to improve the animal productivity that is required for feeding the human population. One of these techniques, the embryo transfer (ET), has presented limitations in the porcine species, which could constrain its use in the porcine industry. To clarify the potential of this technique, we aimed to compare the impact of using ET or artificial insemination (AI) on the phenotype of the offspring during its first days of age, in terms of growth and blood parameters. At birth, the body weight was higher for ET-females than AI-females, but this difference was no longer observed at day 15. On day 3, it was observed a higher concentration of red blood cells, haemoglobin, and haematocrit in females-ET and a higher concentration of white blood cells in both ET-derived piglets (males and females) when compared to AI groups. On day 3, the biochemical analysis showed a higher level of albumin for ET-derived males, and a lower level of bilirubin for ET-females than AI controls. However, all values were within the normal ranges. Our results indicate that piglets derived from ET seem to be phenotypically similar to those born by AI, which provides preliminary evidence that the ET procedure is a safe technique, but additional studies beyond 15 days of life are requested to conclude its global impact. Furthermore, the presented reference values of blood parameters in this species are interesting data for the pig industry.

The effects of natural mating and artificial insemination on reproductive traits of 1-and 2-year-old domestic Turkish geese.

The aim of this study was to assess the sperm quality traits of 1- and 2-year-old ganders and the reproduction traits of 2-year-old domestic Turkish geese in natural mating (NM) and artificial insemination (AI) conditions. The study comprised 72 two-year-old females, 12 one-year-old, and 12 two-year-old ganders. Thirty-six female geese were mated naturally (18 with 1-year-old ganders, 18 with 2-year-old ganders); the remaining thirty-six were inseminated artificially (18 with 1-year-old ganders, 18 with 2-year-old ganders). Twenty-four ganders were separated into groups (12 for NM; 12 for AI). The male:female ratio was 1:3 for NM and AI groups. Egg production, broodiness, fertility and hatching traits were determined in female geese, sperm quality traits such as semen volume, sperm concentration, sperm quality factor (eSQF: ejaculated semen SQF; dSQF: diluted semen SQF), sperm motility, and sperm morphological traits in ganders. The insemination method and gander's age did not affect egg production, AI geese showed significantly more broodiness than NM groups as the breeding months progresses (p < 0.05). Fertility was higher in the groups containing 2-year-old ganders than in those 1-year-old ganders, and NM groups compared to AI (p < 0.05). The insemination method significantly affected semen volume, sperm concentration, eSQF, sperm motility, total live sperm, normal sperm, macro-cephalic sperm, and dead sperm percentages in ganders (p < 0.05).Managing females in the NM system with ganders was able to partially suppress the broodiness behavior, possibly due to synchronization of pair-bond behaviors. Greater fertility was achieved with 2-years-old AI ganders, which had lower dSQF compared to 1-year-old NM ganders. This is a good indication that only SQF is not sufficient to achieve sustainable-desired fertility, and sexual experience is also an important factor.

Investigating Plasma Metabolomic Profiles at the Time of Weaning, Based on Pregnancy Outcome, in Bos Taurus heifers

Abstract The objective of this study was to identify differences in the metabolomic profiles of heifers at the time of weaning based on their subsequent pregnancy outcomes. Angus/Simmental-cross heifers (n = 36) were weighed at weaning and 10ml of blood was collected. The blood plasma and white blood cells (WBCs) were isolated. Heifers were then assessed 30 days prior to artificial insemination (AI) for weight, pelvic area (PA), body condition scores (BCS) and reproductive tract scores (RTS). Reproductively mature heifers underwent an AI program with estrus detection and were then exposed to a bull two weeks after AI. Heifers were categorized into three groups: pregnant by AI, pregnant by natural breeding or open after 3 consecutive estrous cycles. 9 heifers pregnant by AI and 11 open heifers were chosen for metabolomic profiling. Of the 20 heifers selected, there was no difference in weight at weaning (355.6±21.9 kg AI, 364.2±33.3 kg Open, p &amp;gt;0.05), BCS (5.7±0.4 AI, 5.6±0.4 Open, P &amp;gt;0.05), RTS (4.1±0.6 AI, 4.0±0.7 Open, P &amp;gt; 0.05) or PA (173.7±10.8cm2 AI, 175.6±9.1cm2 Open, P &amp;gt; 0.05). Ten metabolites were found to be significantly up or down regulated in the heifers who remained open after three consecutive cycles, when compared to those pregnant by AI. Alanine, cystine, lysine, methionine, tyrosine, tryptophan and valine were down regulated while glycerol, fructose-6-phosphate and ribulose-5-phosphate were found to be up regulated in open heifers (P &amp;lt; 0.05). RNA isolated from WBCs was used to compare the expression of five inflammatory cytokines in the open and pregnant by AI groups (TNFα, IL6, CXCL5, POSTN and MCP1). Inflammatory cytokines were increased in all heifers that remained open after three consecutive cycles (p&amp;lt; 0.05). In summary, the quantity of specific metabolites present within the blood plasma are different at weaning between heifers with differing reproductive potentials. This could potentially be used to develop an assay to aid in selecting replacement females.

Bone marrow mesenchymal stem cells as nuclear donors improve viability and health of cloned horses.

IntroductionCell plasticity is crucial in cloning to allow an efficient nuclear reprogramming and healthy offspring. Hence, cells with high plasticity, such as multipotent mesenchymal stem cells (MSCs), may be a promising alternative for horse cloning. In this study, we evaluated the use of bone marrow-MSCs (BM-MSCs) as nuclear donors in horse cloning, and we compared the in vitro and in vivo embryo development with respect to fibroblasts.Materials and methodsZona-free nuclear transfer was performed using BM-MSCs (MSC group, n=3432) or adult fibroblasts (AF group, n=4527). Embryos produced by artificial insemination (AI) recovered by uterine flushing and transferred to recipient mares were used as controls (AI group).ResultsBlastocyst development was higher in the MSC group than in the AF group (18.1% vs 10.9%, respectively; p<0.05). However, pregnancy rates and delivery rates were similar in both cloning groups, although they were lower than in the AI group (pregnancy rates: 17.7% [41/232] for MSC, 12.5% [37/297] for AF and 80.7% [71/88] for AI; delivery rates: 56.8% [21/37], 41.5% [17/41] and 90.1% [64/71], respectively). Remarkably, the gestation length of the AF group was significantly longer than the control (361.7±10.9 vs 333.9±8.7 days), in contrast to the MSC group (340.6±8.89 days). Of the total deliveries, 95.2% (20/21) of the MSC-foals were viable, compared to 52.9% (9/17) of the AF-foals (p<0.05). In addition, the AF-foals had more physiological abnormalities at birth than the MSC-foals; 90.5% (19/21) of the MSC-delivered foals were completely normal and healthy, compared to 35.3% (6/17) in the AF group. The abnormalities included flexural or angular limb deformities, umbilical cord enlargement, placental alterations and signs of syndrome of neonatal maladjustment, which were treated in most cases.ConclusionIn summary, we obtained 29 viable cloned foals and found that MSCs are suitable donor cells in horse cloning. Even more, these cells could be more efficiently reprogrammed compared to fibroblasts.

Morbidity and mortality among very preterm singletons following fertility treatment in Australia and New Zealand, a population cohort study

BackgroundDue to high rates of multiple birth and preterm birth following fertility treatment, the rates of mortality and morbidity among births following fertility treatment were higher than those conceived spontaneously. However, it is unclear whether the rates of adverse neonatal outcomes remain higher for very preterm (<32 weeks gestational age) singletons born after fertility treatment. This study aims to compare adverse neonatal outcomes among very preterm singletons born after fertility treatment including assisted reproductive technology (ART) hyper-ovulution (HO) and artificial insemination (AI) to those following spontaneous conception.MethodsThe population cohort study included 24069 liveborn very preterm singletons who were admitted to Neonatal Intensive Care Unit (NICU) in Australia and New Zealand from 2000 to 2010. The in-hospital neonatal mortality and morbidity among 21753 liveborn very preterm singletons were compared by maternal mode of conceptions: spontaneous conception, HO, ART and AI. Univariate and multivariate binary logistic regression analysis was used to examine the association between mode of conception and various outcome factors. Odds ratio (OR) and adjusted odds ratio (AOR) and 95% confidence interval (CI) were calculated.ResultsThe rate of small for gestational age was significantly higher in HO group (AOR 1.52, 95% CI 1.02–2.67) and AI group (AOR 2.98, 95% CI 1.53–5.81) than spontaneous group. The rate of birth defect was significantly higher in ART group (AOR 1.71, 95% CI 1.36–2.16) and AI group (AOR 3.01, 95% CI 1.47–6.19) compared to spontaneous group. Singletons following ART had 43% increased odds of necrotizing enterocolitis (AOR 1.43, 95% CI 1.04–1.97) and 71% increased odds of major surgery (AOR 1.71, 95% CI 1.37–2.13) compared to singletons conceived spontaneously. Other birth and NICU outcomes were not different among the comparison groups.ConclusionsCompared to the spontaneous conception group, risk of congenital abnormality significantly increases after ART and AI; the risk of morbidities increases after ART, HO and AI. Preconception planning should include comprehensive information about the benefits and risks of fertility treatment on the neonatal outcomes.

Effect of time of artificial insemination after oestrus detection on non-return rate of lactating dairy cows on pasture

AIMS: To determine the difference in reproductive performance between cows detected in oestrus during morning or afternoon milking when artificial insemination (AI) was carried out once daily, either after the morning or afternoon milking.METHODS: The study used 20,816 records for cows in 30 spring calving dairy herds that used a camera-based system for oestrus detection during both morning and afternoon milkings. This system automatically determined whether a pressure-sensitive oestrus detection device had been activated or not, or was missing. In all study herds cows were milked twice daily and AI was performed by professional AI technicians once daily, after either morning or afternoon milking. The time of recorded oestrus was classified into AM or PM oestrus groups using 12:00 noon as the cut-off point and time of AI was classified into AM or PM AI groups using 13:00 as the cut-off point. Reproductive performance was determined using non-return to oestrus (NRR) between 2 and 24 days after AI, and was compared between oestrus and AI groups using generalised linear mixed models.RESULTS: Most AI (18,621/20,816; 89%) were carried out after morning milking, and more cows were recorded in oestrus during morning milking (12,328/20,816; 59%) than during afternoon milking (8,488/20,816; 41%). The NRR of cows inseminated after morning milking did not differ (OR=1.04; 95% CI=0.97–1.10) for cows recorded in oestrus in the morning (LSM=68.6 (95% CI=66.3–70.9)%) or afternoon (LSM=67.9 (95% CI=65.4–70.2)%); and did not differ for cows inseminated after the afternoon milking (OR=1.10; 95% CI=0.92–1.32) for cows recorded in oestrus in the morning (LSM=63.4 (95% CI=58.2–68.2)%) or afternoon (LSM=61.2 (95% CI=55.8–66.3)%). There were no differences in NRR between cows detected in oestrus during the morning or the afternoon milking after AI with either liquid (OR=1.04; 95% CI=0.97–1.12) or frozen-thawed (OR=1.02; 95% CI=0.88–1.18) semen.CONCLUSIONS AND CLINICAL RELEVANCE: Results from the present study show that, under New Zealand conditions, the difference in NRR between cows first detected in oestrus during morning milking and those first detected in oestrus during afternoon milking is likely small when AI is carried out once daily after either morning or afternoon milking, regardless of whether the semen used for AI is liquid or frozen. Because twice daily AI is more costly than once daily AI, these results do not support a change to the current once daily AI practice in New Zealand.

Fertility response of artificial insemination methods in sheep with fresh and frozen-thawed semen

The aim of this study was to evaluate the fertility response of artificial insemination (AI) methods with fresh and frozen sperm in sheep. In experiment 1, one hundred and fifty fat tailed Zandi ewes were assigned into 3 equal groups and inseminated with three AI methods consisting of vaginal, laparoscopic and trans-cervical AI with fresh semen. In experiment 2, a factorial study (3 AI methods × 2 extenders) was used to analyze the effects of three AI methods and two freezing extenders containing soybean lecithin (SL) or Egg yolk (EY) on reproductive performance of 300 fat tailed Zandi ewes. Also, total motility, progressive motility, viability and lipid peroxidation of semen were evaluated after freeze-thawing in two extenders. In result, there was no significant difference among three AI methods when fresh semen was used. In experiment 2, the highest percentage of pregnancy rate, parturition rate and lambing rate were obtained in laparoscopic AI group (P < 0.05). Although pregnancy rate, parturition rate and lambing rate in trans-cervical group were higher (P < 0.05) than vaginal group, the results were not as high as laparoscopic group. No difference was observed between SL and EY extenders and their performance was close to each other. It can be concluded that although no difference was observed on reproductive performance for fresh semen, trans-cervical AI was more efficient than vaginal method when frozen-thawed semen was used, but its efficiency was not as high as laparoscopic method. Also, SL extender can be an efficient alternative extender to preserve ram sperm during cryopreservation procedure without adverse effects of EY.

A comparative study on the embryo-fetal development in rabbits after artificial insemination

Objectives: Artificial insemination (AI) is the introduction of spermatozoa into a female's uterus or cervix for the purpose of achieving pregnancy. It is a fertility treatment for humans, in animal breeding and embryo-fetal developmental studies. This study investigated the embryo-fetal development in the rabbit via artificial insemination by evaluating the litter size, reproductive data and external morphological abnormalities after insemination. Methods: Ten adult female and three male rabbits weighing 1.8 kg and 2 kg, respectively were used. Group A served as the natural mating, while Group B served as the AI group, and the males served as semen donors. On day 28 of gestation, does were subjected to caesarean section. The ovaries and uteri were removed and examined for the number of corpora lutea and the status of all implantation. Results: Results showed a significant increase in fetal weight, total fetal number, total resorption sites, number of implantation and total number of live foetuses (p 0.05). A conception rate of 100% was observed in Group A compared to Group B with 80% conception rate. External examination carried out on the foetuses revealed no external abnormalities in both groups. Conclusion: The results of this study show the clear advantages in the use of rabbits for AI in terms of embryo-fetal developmental studies. Keywords: artificial insemination; caesarean section; embryo-fetal development

Developmental Outcome and Related Abnormalities in Goats: Comparison Between Somatic Cell Nuclear Transfer- and In Vivo-Derived Concepti During Pregnancy Through Term.

Cloning by somatic cell nuclear transfer (SCNT) is characterized by low efficiency and the occurrence of developmental abnormalities, which are rather poorly studied phenomena in goats. This study aimed at comparing overall SCNT efficiency in goats by using in vitro-matured (IVM) or in vivo-matured oocytes and fibroblast donor cells (mock transfected, transgenic, or wild type), also characterizing symptoms of the Abnormal Offspring Syndrome (AOS) in development, comparing results with pregnancies produced by artificial insemination (AI) and in vivo-derived (IVD) embryos. The SCNT group had lower pregnancy rate (18.3%, 11/60), total number of concepti (20.0%, 12/60), term births (3.3%, 2/60), and live births (1.7%, 1/60) than both the IVD (77.8%, 7/9; 155.5%, 14/9; 122.2%, 11/9; 88.8%, 8/9) and the AI (71.4%, 10/14; 121.4%, 17/14; 100%, 14/14; 78.5%, 11/14) groups, respectively (p < 0.05). No SCNT pregnancies reached term using IVM oocytes, but in vivo-matured oocytes resulted in two term transgenic cloned kids. The proportion fetal membrane (FM) weight/birth weight reflected an increase in FM size and cotyledonary enlargement in clones, for disproportionally bigger newborns in relation to cotyledonary numbers. Overall, goat cloning showed losses and abnormality patterns similar to the AOS in cloned cattle and sheep, which have not been previously well recognized in goats.

Effects of AI protocol and time interval from onset of estrus to AI on conception rate in Japanese Black cows

Two different artificial insemination (AI) protocols were investigated to determine the effect of the time interval from the onset of estrus (as detected by a pedometer) to the AI on the conception rate in Japanese Black cows. Seventy-three cows were divided into two groups that received AI either after the induction of synchronized ovulation (synchronized AI group; n = 26) or at the time of observed estrus (control AI group; n = 47). Each group was further divided into two subgroups, which were artificially inseminated either 0-12 h (early AI group; n = 21) or 12-24 h (late AI group; n = 52) after the onset of estrus. There was no significant difference in the conception rate between the synchronized AI and control AI groups. The AI protocol and the detection of estrus using a threshold of counted steps (as measured by a pedometer) in this study could be effective for planned reproduction management without the observation of standing estrus in Japanese Black cows.

Pregnancy rate following artificial insemination or natural service in postpartum estrus synchronized beef cattle

The objective of this study was to investigate the pregnancy rate following artificial insemination (AI) or natural service (NS) in postpartum estrous synchronized beef cattle. A total of 85 Brangus cows, postpartum, were divided into 2 groups. Group 1 consisted of 35 cows and was further subdivided into 7 groups, each consisted of 5 cows that were naturally mated. Group 2 consisted of 40 cows that were artificially inseminated. Estrus synchronization was carried out using a controlled internal drug releasing device (CIDR) containing 1.38 mg of progesterone, for 7 days. Group 1 cows were mixed with bulls at a 1:5 ratio of bull:cows for 7 days and group 2 cows were inseminated 55-58 h after the CIDR removal. Pregnancy was determined using transrectal ultrasonography 32 days after NS and AI. The pregnancy rate was higher in the NS group (28.6%) than in the AI group (18.0%), but the difference was not significant (P > 0.05).

Morbidity-mortality and performance evaluation of Brahman calves from in vitro embryo production

BackgroundThe use of bovine in vitro embryo production (IVP) increases the reproductive potential of genetically superior cows, enabling a larger scale of embryo production when compared with other biotechnologies. However, deleterious effects such as abnormal fetal growth, longer gestation period, increased birth weight, abortion, preterm birth and higher rates of neonatal mortality have been attributed to IVP. The aim of this study was to compare the influence of in vitro embryo production and artificial insemination (AI) on gestation length, complications with birth, birth weight, method of feeding colostrum, passive transfer of immunity, morbidity-mortality, and performance in Brahman calves.ResultsWhilst gestation length and birth weight were significantly increased in IVP-derived calves, no difference in weaning weight was observed between groups. The passive transfer of immunity (PT), was assessed in IVP (n = 80) and AI (n = 20) groups 24 hours after birth by determination of gamma-glutamyl transferase (GGT) and gammaglobulin activity as well as by quantification of the concentration of total protein in serum. No differences in passive transfer or incidences of dystocia and diseases at weaning were observed between groups. Birth weight, method of feeding colostrum and dystocia were not correlated with PT in either group.ConclusionsIn this study, in vitro embryo production did not affect the health status, development, or passive transfer of immunity in Brahman calves.

Efficacy of embryo transfer in lactating dairy cows during summer using fresh or vitrified embryos produced in vitro with sex-sorted semen

The objective was to determine whether transfer of fresh or vitrified embryos produced in vitro with sex-sorted semen improves pregnancy and calving rates during summer in lactating dairy cows compared with artificial insemination (AI). Lactating dairy cows (n=722) were enrolled during summer months at 2 commercial dairies in Central Texas and randomly assigned to 1 of 3 treatments: AI with conventional semen (n=227), embryo transfer-vitrified (ET-V; n=279) or embryo transfer-fresh (ET-F; n=216). Embryos were produced in vitro using sex-sorted semen and with Block-Bonilla-Hansen-7 culture medium. For vitrification, grade 1 expanded blastocysts were harvested on d 7 after fertilization and vitrified using the open-pulled straw method. Fresh embryos were grade 1 blastocysts and expanded blastocysts harvested on d 7 after fertilization. Cows were submitted to the Ovsynch56 protocol: d −10 GnRH, d −3 PGF2α, d −1 GnRH and d 0 timed AI; or Select Synch protocol: d −9 GnRH, d −2 PGF2α, and AI following detected estrus (day of AI=d 0). On d 7, all cows were examined for presence of a corpus luteum (CL). A vitrified or fresh embryo was transferred to cows with CL in ET-V and ET-F groups. Cows were considered synchronized if progesterone was <1ng/mL on d 0 and a CL was present on d 7. At d 40±7 of gestation, the percentage of cows pregnant was greater for the ET-F compared with the ET-V and AI groups among all cows (42.1 vs. 29.3 and 18.3%, respectively) and synchronized cows (45.5 vs. 31.6 and 24.8%, respectively). Also, the percentage of cows pregnant was greater for the ET-V than the AI group among all cows and tended to be greater among synchronized cows. At d 97±7 of gestation, the percentage of cows pregnant among all cows was greater for ET-F and ET-V groups than for the AI group (36.4 and 25.7 vs. 17.0%, respectively) and the percentage for the ET-F group was greater than for the ET-V group. Among synchronized cows, the percentage of cows pregnant was significantly increased for the ET-F group than for ET-V and AI groups (39.4 vs. 27.8 and 23.1%, respectively) and no difference was found between ET-V and AI groups. No effect of treatment on embryo loss was observed. The percentage of cows with live births was significantly increased for the ET-F than for ET-V and AI groups among all cows (27.5 vs. 17.1 and 14.6%, respectively) and synchronized cows (29.9 vs. 18.5 and 20.0%, respectively). The percentage of cows giving birth to a live heifer was significantly increased for the ET-F and ET-V groups compared with the AI group among all cows (79.1 and 72.5 vs. 50.0%, respectively) and synchronized cows (79.1 and 72.5 vs. 50.0%, respectively). No difference existed between ET-F and ET-V groups for percent live heifer births but both were greater than for the AI group. The transfer of fresh embryos produced in vitro using sex-sorted semen to lactating dairy cows during summer can effectively increase the percentage of cows that establish pregnancy and also the percentage of cows that give birth to a live heifer compared with percentages from AI with conventional semen.

Gestation length, birth weight and offspring gender ratio of in vitro-produced Gyr ( Bos indicus) cattle embryos

In vitro embryo production (IVP) has been suggested to result in a greater proportion of male calves, longer gestation and heavier offspring than artificial insemination in Bos taurus cattle. Despite the increasing use of IVP in tropical countries, its effects upon these traits in Bos indicus have not been conclusively investigated. Gyr is a B. indicus dairy breed with known physiological differences from B. taurus, such as a longer gestation period and lighter offspring. The aim of this study was to evaluate the effect of IVP on gestation length, birth weight and gender ratio in Gyr offspring. Oocytes were recovered from Gyr cows by ovum pick-up and were matured and fertilized with thawed Gyr semen in vitro. Embryos were cultured in CR2aa medium with cumulus cells and 10% fetal calf serum under 5% CO 2 at 38.5 °C in air. Seven- to eight-day blastocysts were transferred to synchronized recipients. Data on gestation length and birth weight of calves from in vitro-produced embryos were compared to data obtained from Gyr calves produced by artificial insemination (AI) and natural breeding (NB) during the same period using analysis of variance, and the gender ratio was compared to the expected 1:1 ratio using a chi-square test. IVP increased ( P < 0.01) the percentage of male offspring (76.9%) compared to the expected 1:1 ratio, while no difference ( P > 0.05) was observed in the AI and NB groups. Gestation length was similar ( P > 0.05) between the IVP and AI groups, but IVP-derived offspring were heavier ( P < 0.05) than AI- and NB-derived ones, mainly for male calves ( P < 0.05). These data show that in vitro production affects the subsequent development of Gyr embryos, resulting in a skewed sex ratio and increased birth weight.

A differential staining protocol to investigate sperm selection in the mare`s reproductive tract after heterospermic insemination

In vitro embryo production (IVP) has been suggested to result in a greater proportion of male calves, longer gestation and heavier offspring than artificial insemination in Bos taurus cattle. Despite the increasing use of IVP in tropical countries, its effects upon these traits in Bos indicus have not been conclusively investigated. Gyr is a B. indicus dairy breed with known physiological differences from B. taurus, such as a longer gestation period and lighter offspring. The aim of this study was to evaluate the effect of IVP on gestation length, birth weight and gender ratio in Gyr offspring. Oocytes were recovered from Gyr cows by ovum pick-up and were matured and fertilized with thawed Gyr semen in vitro. Embryos were cultured in CR2aa medium with cumulus cells and 10% fetal calf serum under 5% CO2 at 38.5 °C in air. Seven- to eight-day blastocysts were transferred to synchronized recipients. Data on gestation length and birth weight of calves from in vitro-produced embryos were compared to data obtained from Gyr calves produced by artificial insemination (AI) and natural breeding (NB) during the same period using analysis of variance, and the gender ratio was compared to the expected 1:1 ratio using a chi-square test. IVP increased (P < 0.01) the percentage of male offspring (76.9%) compared to the expected 1:1 ratio, while no difference (P > 0.05) was observed in the AI and NB groups. Gestation length was similar (P > 0.05) between the IVP and AI groups, but IVP-derived offspring were heavier (P < 0.05) than AI- and NB-derived ones, mainly for male calves (P < 0.05). These data show that in vitro production affects the subsequent development of Gyr embryos, resulting in a skewed sex ratio and increased birth weight.