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At least 397 records · Page 22Linked to original sources
PubMed2026

Hormone priming and metabolic engineering of phytohormone crosstalk in rice under combined biotic and abiotic stresses: a multi-omics perspective for climate-resilient crop development.

Rice (Oryza sativa L.) is the caloric backbone for more than half of humanity, yet it remains one of the most vulnerable crops to the simultaneous biotic and abiotic stresses exacerbated by climate change. Phytohormone priming and the complex crosstalk networks governed by transcription factor hubs like WRKY, MYB, and NAC serve as the central adaptive mechanism for stress resilience. This review synthesizes how multi-omics integration, including spatial and single-cell transcriptomics, is resolving the molecular architecture of hormonal priming and epigenetic stress memory. We critically evaluate advanced metabolic engineering and genome-editing strategies such as CRISPR-Cas9, base/prime editing, and synthetic gene circuits that enable precision modifications to decouple stress tolerance from historical yield penalties. Furthermore, we discuss the emerging roles of microbiome-assisted priming via synthetic consortia and the application of artificial intelligence and digital twins (continuously updated computational models of crop physiology) for predictive stress management. By integrating these diverse technological pillars, we propose a systems-level roadmap for developing climate-resilient rice cultivars capable of maintaining yield stability across a volatile combinatorial stress landscape. This synthesis provides a framework for translating mechanistic hormonal insights into field-applicable cultivars to ensure global food security.

CRISPR↗
PubMed1992

High density molecular linkage maps of the tomato and potato genomes.

High density molecular linkage maps, comprised of more than 1000 markers with an average spacing between markers of approximately 1.2 cM (ca. 900 kb), have been constructed for the tomato and potato genomes. As the two maps are based on a common set of probes, it was possible to determine, with a high degree of precision, the breakpoints corresponding to 5 chromosomal inversions that differentiate the tomato and potato genomes. All of the inversions appear to have resulted from single breakpoints at or near the centromeres of the affected chromosomes, the result being the inversion of entire chromosome arms. While the crossing over rate among chromosomes appears to be uniformly distributed with respect to chromosome size, there is tremendous heterogeneity of crossing over within chromosomes. Regions of the map corresponding to centromeres and centromeric heterochromatin, and in some instances telomeres, experience up to 10-fold less recombination than other areas of the genome. Overall, 28% of the mapped loci reside in areas of putatively suppressed recombination. This includes loci corresponding to both random, single copy genomic clones and transcribed genes (detected with cDNA probes). The extreme heterogeneity of crossing over within chromosomes has both practical and evolutionary implications. Currently tomato and potato are among the most thoroughly mapped eukaryotic species and the availability of high density molecular linkage maps should facilitate chromosome walking, quantitative trait mapping, marker-assisted breeding and evolutionary studies in these two important and well studied crop species.

Centromere↗
PubMed1984

Trace element studies in weanling rats: maternal diets and baseline tissue mineral values.

The initial nutritional status of experimental animals can influence their response to subsequent dietary regimens. In the present study, we determined the variations in minerals in diet NIH-31, a breeding colony stock diet, and in tissues of weanling rats nursed by dams fed this diet. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used to determine nine elements (Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn) in diet and in liver, kidney, spleen, duodenum and femur from 22- to 26-day-old rats. Wet digestions were performed in mixtures of nitric, perchloric, and sulfuric acids (diets and soft tissues) or nitric and perchloric acids (femur). Solution concentrations ranged from less than 25 ng/ml for the trace elements to greater than 100 micrograms/ml for the major elements. Large variations in mineral content were found between batches of commercially prepared NIH-31 diet; relative amounts of Cu, Fe, Mn and Zn varied markedly. Significant differences in concentrations of major and trace minerals in liver, kidney, spleen and duodenal tissue were found among groups of weanling rats obtained from the same supplier at different times. Mn was readily quantitated in all tissues except spleen, where it was below detection limits. The precision obtained with the ICP-AES methodology has significant advantages for establishing variations in tissue mineral levels.

Animal Nutritional Physiological Phenomena↗
PubMed1994

[Scrapie from the clinical aspect].

The first cases of scrapie in the Federal Republic of Germany since 1945 occurred in 1990 and 1991. The disease was found in three flocks of Suffolk sheep and it was probably brought to Germany by breeding sheep from France. Scrapie is a transmissible degenerative disease of the central nervous system with a slowly progressing but always fatal course. The scrapie agent is highly resistant against environmental influences as well as against disinfectants. Incubation period and clinical signs of scrapie vary from flock to flock, depending on genetical factors of infected sheep and depending on the involved scrapie strain. In infected flocks normally not more than 1% of the sheep show clinical symptoms. Affected sheep are usually more than two years old (maximum incidence at three years of age). First signs of the disease may be changes in behaviour or pruritus or locomotor symptoms. When the disease progresses, all sheep loose flesh and within some weeks up to some months they get weaker and weaker until they finally die in recumbency. Scrapie cannot be detected in living animals and the disease may be overlooked during autopsy, because in the final stage of the disease many sheep die from non-specific secondary infections. In suspected cases of scrapie, the practicing veterinarian must give a precise history to the pathologist and he must ask for histopathological examination of the brain.

Animals↗
PubMedDate not supplied

A radiographic stress technique for evaluation of coxofemoral joint laxity in dogs.

OBJECTIVE: To develop a radiographic stress technique to quantify hip joint laxity in dogs. STUDY DESIGN: Prospective study on client-owned dogs presented for hip dysplasia screening. ANIMAL POPULATION: 302 nonselected dogs (63 breeds). METHODS: Dogs were sedated and placed in dorsal recumbency. During pelvic radiography, the femoral heads were displaced manually in a craniodorsal direction. On these stress radiographs, the degree of lateral displacement of the femoral heads was assessed in terms of a subluxation index (SI) and compared with the degree of femoral head subluxation and the severity of hip dysplasia found on conventional extended hindlimb radiographs. RESULTS: The degree of subluxation on stress radiographs was significantly greater than on conventional radiographs. Correlation between the severity of canine hip dysplasia (CHD), graded according to conventional techniques, and the degree of subluxation, induced by radiographic stress technique, was positive (r = .57; P<.0001). Two critical SI values were noted. Of the dogs with an SI value of 0.3 or less, 99% were classified as CHD grade normal, borderline, or mildly dysplastic. In dogs with an SI value between 0.3 and 0.5, CHD grading ranged from normal to severely dysplastic. Of the dogs with an SI value greater than 0.5, 95% had dysplastic hip joints. CONCLUSIONS: Hip joint laxity cannot be quantified precisely on standard position radiographs. The proposed stress technique yields significantly higher degrees of femoral head subluxation than the standard position.

Animals↗
PubMed2006

Male-induced short oestrous and ovarian cycles in sheep and goats: a working hypothesis.

The existence of short ovulatory cycles (5-day duration) after the first male-induced ovulations in anovulatory ewes and goats, associated or not with the appearance of oestrous behaviour, is the origin of the two-peak abnormal distribution of parturitions after the "male effect". We propose here a working hypothesis to explain the presence of these short cycles. The male-effect is efficient during anoestrus, when follicles contain granulosa cells of lower quality than during the breeding season. They generate corpora lutea (CL) with a lower proportion of large luteal cells compared to small cells, which secrete less progesterone, compared to what is observed in the breeding season cycle. This is probably not sufficient to block prostaglandin synthesis in the endometrial cells of the uterus at the time when the responsiveness to prostaglandins of the new-formed CL is initiated and, in parallel, to centrally reduce LH pulsatility. This LH pulsatility stimulates a new wave of follicles secreting oestradiol which, in turn, stimulates prostaglandin synthesis and provokes luteolysis and new ovulation(s). The occurrence of a new follicular wave on days 3-4 of the first male-induced cycle and the initiation of the responsiveness to prostaglandins of the CL from day 3 of the oestrous cycle are probably the key elements which ensure such regularity in the duration of the short cycles. Exogenous progesterone injection suppresses short cycles, probably not by delaying ovulation time, but rather by blocking prostaglandin synthesis, thus impairing luteolysis. The existence, or not, of oestrous behaviour associated to these ovulatory events mainly varies with species: ewes, compared to does, require a more intense endogenous progesterone priming; only ovulations preceded by normal cycles are associated with oestrous behaviour. Thus, the precise and delicate mechanism underlying the existence of short ovulatory and oestrous cycles induced by the male effect appears to be dependent on the various levels of the hypothalamo-pituitary-ovario-uterine axis.

Animals↗
PubMedDate not supplied

[Joint research on the precise determination of the energy and protein requirements of fattening pigs. 3. The energy requirement of hybrid swine].

The energy requirement for hybrid pigs ((large white X land race pig) X line 150) in the live weight range between 35 and 120 kg is derived from 242 measurings of the total metabolism as the sum of energy requirement for maintenance and energy requirement for live weight gain. Energy requirement is estimated by means of the following equation: (Formula: see text). Energy maintenance requirement, energy content per 1 kg live weightgain in dependence of the daily gain and the derived energy requirement for growth and fattening are compared with corresponding results from investigations with pigs of the species large white and land race pig. Essential differences concerning parameters of energy metabolism determining the requirement could not be detected.

Animal Nutritional Physiological Phenomena↗
PubMed2006

Analysis of kinesin-2 function in photoreceptor cells using synchronous Cre-loxP knockout of Kif3a with RHO-Cre.

PURPOSE: To determine the relationship between the presence of kinesin-2 and photoreceptor cell viability and opsin transport, by generating RHO-Cre transgenic mice and breeding them to mice with a floxed kinesin-2 motor gene. METHODS: Different lines of RHO-Cre transgenic mice were generated and characterized by transgene expression, histology, and electrophysiology. Mice from one line, showing uniform transgene expression, were crossed with Kif3a(flox)/Kif3a(flox) mice. The time courses of photoreceptor Cre expression, KIF3A loss, ectopic opsin accumulation, and photoreceptor cell death were determined by Western blot analysis and microscopy. RESULTS: One of the RHO-Cre lines effected synchronous expression of Cre and thus uniform excision of Kif3a(flox) in rod photoreceptors across the retina. After the neonatal production of CRE and the initiation of KIF3A loss, ectopic accumulation of opsin was detected by postnatal day (P)7, and ensuing photoreceptor cell death was evident after P10 and almost complete by P28. Of importance, the photoreceptor cilium formed normally, and the disc membranes of the nascent outer segment remained normal until P10. CONCLUSIONS: The RHO-Cre-8 mice provide an improved tool for studying gene ablation in rod photoreceptor cells. Regarding kinesin-2 function in photoreceptor cells, the relatively precise timing of events after CRE excision of Kif3a(flox) allows us to conclude that ectopic opsin is a primary cellular lesion of KIF3A loss, consistent with the hypothesis that opsin is a cargo of kinesin-2. Moreover, it demonstrates that KIF3A loss results in very rapid photoreceptor cell degeneration.

Animals↗
PubMed2005

Radiation of pollination systems in the Iridaceae of sub-Saharan Africa.

BACKGROUND: Seventeen distinct pollination systems are known for genera of sub-Saharan African Iridaceae and recurrent shifts in pollination system have evolved in those with ten or more species. Pollination by long-tongued anthophorine bees foraging for nectar and coincidentally acquiring pollen on some part of their bodies is the inferred ancestral pollination strategy for most genera of the large subfamilies Iridoideae and Crocoideae and may be ancestral for the latter. Derived strategies include pollination by long-proboscid flies, large butterflies, night-flying hovering and settling moths, hopliine beetles and sunbirds. Bee pollination is diverse, with active pollen collection by female bees occurring in several genera, vibratile systems in a few and non-volatile oil as a reward in one species. Long-proboscid fly pollination, which is apparently restricted to southern Africa, includes four separate syndromes using different sets of flies and plant species in different parts of the subcontinent. Small numbers of species use bibionid flies, short-proboscid flies or wasps for their pollination; only about 2 % of species use multiple pollinators and can be described as generalists. SCOPE: Using pollination observations for 375 species and based on repeated patterns of floral attractants and rewards, we infer pollination mechanisms for an additional 610 species. Matching pollination system to phylogeny or what is known about species relationships based on shared derived features, we infer repeated shifts in pollination system in some genera, as frequently as one shift for every five or six species of southern African Babiana or Gladiolus. Specialized systems using pollinators of one pollination group, or even a single pollinator species are the rule in the family. Shifts in pollination system are more frequent in genera of Crocoideae that have bilaterally symmetric flowers and a perianth tube, features that promote adaptive radiation by facilitating precise shifts in pollen placement, in conjunction with changes in flower colour, scent and tube length. CONCLUSIONS: Diversity of pollination systems explains in part the huge species diversity of Iridaceae in sub-Saharan Africa, and permits species packing locally. Pollination shifts are, however, seen as playing a secondary role in speciation by promoting reproductive isolation in peripheral, ecologically distinct populations in areas of diverse topography, climate and soils. Pollination of Iridaceae in Eurasia and the New World, where the family is also well represented, is poorly studied but appears less diverse, although pollination by both pollen- and oil-collecting bees is frequent and bird pollination rare.

Africa South of the Sahara↗
PubMed2005

Impact of maturity rate of daughters on genetic ranking of Holstein bulls.

If genetic evaluations are calculated with a single-trait repeatability model, evaluation changes may be attributed in part to bulls that have daughters that deviate considerably from the typical response to aging. Differences in maturity rate of bull daughters were examined to determine whether they influence change in bull evaluations. Standardized milk records for Holsteins that first calved between 1960 and 1998 were used to calculate 12 tailored predicted transmitting abilities (PTA) for each bull. Predicted transmitting abilities were tailored from combinations of 4 annual cut-off dates and 3 parities. Date screening selected cows first calving before January of 1996, 1997, 1998, or 1999. Parity screening selected milk records from the first 1, 2, or 3 parities. Therefore, 4 evaluations (PTA1) included only first-parity records available for daughters and contemporaries prior to the respective years designated. Four more evaluations (PTA(1,2)) included the records from the first 2 parities for cows first calving prior to those same year cutoffs; likewise, the last 4 evaluations (PTA(1,2,3)) included records from the first 3 parities. Stability of bull evaluations (standard deviations of differences as well as correlations between bull evaluations) across time was compared. Bulls born after 1984 with > or =500 daughters were of interest because of the high precision of evaluations and recent activity. Tailored PTA of those bulls had more uniformity across years in mean records per daughter than did official USDA PTA. Standard deviation of differences in PTA1, PTA(1,2), and PTA(1,2,3) for milk between evaluation years 1996 and 1997 were 28, 28, and 27 kg compared with 63 kg for official evaluations; similarly, between 1996 and 1999, SD were 36, 32, and 32 kg compared with 80 kg. Results suggested that a modification to the current evaluation model to account for maturity rate should reduce fluctuations in individual bull PTA across time and may improve accuracy of evaluations.

Aging↗
PubMed1988

A new model of genetic hypertension in rats with superficial glomeruli.

Despite renal involvement in the genesis of hypertension, the precise renal hemodynamic events prior to and during development of hypertension have not been obtainable by direct study in the available rat models of genetic hypertension. We have developed a model of genetic salt-sensitive hypertension in rats with superficial glomeruli, using the protocol described by Dahl to develop the Brookhaven model. Adult Munich Wistar rats were purchased from Charles River and bred in our laboratory. Offspring were allowed to mature without intervention. Systolic blood pressure and body weight were measured weekly to determine the normal longitudinal changes with increasing age for this strain. Balance studies were also carried out longitudinally, and during these studies plasma renin activity (PRA) was determined. When the rats were 16 weeks old, the availability of superficial glomeruli was assessed under microscopic examination and only those rats with numerous superficial glomeruli/field were mated. The offspring of these breeders were used as the zero generation (F0) of salt-sensitive rats, and were treated as described by Dahl. Systolic blood pressure, body weights and balance studies were carried out in this and in all subsequent generations. Sibling breeding was maintained and rats were bred for salt-sensitivity (systolic blood pressure greater than 155 mmHg at the age of 2 months) and availability of superficial glomeruli. Those rats with systolic blood pressure of less than 120 mmHg were bred in an attempt to develop a salt-resistant strain, and untreated Munich Wistar rats were bred to provide another control.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

B virus-specific pathogen-free (SPF) breeding colonies of macaques: issues, surveillance, and results in 1992.

The NIH's National Center for Research Resources, Comparative Medicine Program has sponsored a multi-institutional program for the establishment of specific pathogen-free (SPF) macaque colonies. Herpes B virus (Cercopithecine herpesvirus I) has been targeted as part of this surveillance. Participating institutions have established individual timetables for frequency of testing, types of monitoring, and husbandry techniques, all with the common goal of producing pathogen-free monkeys for research. From January 1990 through December 1992, we screened animals for evidence of B virus infection, using ELISA and immunoblot to detect humoral antibodies. A total of 984 animals were tested during the first year of the program. At the start of the third year, 631 animals remained in our testing program. Of the 36.9% eliminated for all causes over a 3-year period, B virus screening accounted for 12.1, 1.2, and 0.5% during years 1, 2, and 3, respectively. The greatest threat to the success of the program comes from failure to detect seronegative animals with latent infections, if they do indeed exist, either in first-year animals or animals introduced in subsequent years. The best assurance that a colony is SPF comes from negative results of repeated testing. Introducing new animals into an established SPF colony should be done only after careful screening. Simulations using mathematical models suggest that the best way to detect seronegative animals with latent infections is monthly or bimonthly testing separated by a waiting period. Duration of the waiting period cannot be defined precisely until more is known about the reactivation potential of putative seronegative animals with latent infections.

Animals↗
PubMed1998

Molecular characterization of endogenous viral genes of the avian leukosis virus family in an experimental population of brown-egg layers.

Retroviral DNA sequences similar to the exogenous avian leukosis virus can be found in the genome of many chicken breeds and have been identified as the ALVE family of endogenous viral (ev) genes. Most of them have been described by a restriction fragment length polymorphism (RFLP) procedure with two restriction enzymes and a full length viral probe. In order to facilitate the comparison of ALVE genes between strains, the nomenclature workshop held at the XXIV International Society for Animal Genetics Congress recommended that four enzymes and several viral subprobes be used to characterize each locus. This approach has been followed in the present study of a Rhode Island Red experimental population. A previous study had identified ev genes with the SacI and BamHI enzymes and the Rous-associated virus-2 probe (RAV-2). Chickens carrying only one ALVE locus at a time have been produced to facilitate the analysis. Additional enzymes (EcoRI, HindIII, and KpnI), the full probe RAV-2 and three viral subprobes for the gag, pol, and LTR regions have been used. In addition, a PCR diagnostic test has been used to search for homologies with the ALVE1 (= ev1), ALVE6 (= ev6) and evA loci. Currently, 12 loci have been identified precisely: three were identical to ALVE loci described previously, either in White Leghorns, ALVE6 and ALVE18 (= ev18) or in broilers (evB8). In addition, the evB8 locus was found to be identical to the evA locus previously described in brown-egg layers. Nine loci appeared specific to this Rhode Island Red population. Four of these specific loci were complete and one of them could be considered of characteristic of this population, because of its very high frequency. The remaining five specific loci showed small deletions, either in the pol region for one of them or in the env region for three of them or at the 3' long terminal repeat for one of them. Altogether, 5 out of 12 loci were structurally complete, which could suggest that deleted proviruses may have been preferentially retained.

Animals↗
PubMed2005

Molecular dissection of interspecific variation between Gossypium hirsutum and G. barbadense (cotton) by a backcross-self approach: II. Fiber fineness.

A backcross-self population from a cross between Gossypium hirsutum and G. barbadense was used to dissect the molecular basis of genetic variation governing two parameters reflecting lint fiber fineness and to compare the precision of these two measurements. By applying a detailed restriction fragment length polymorphism (RFLP) map to 3,662 BC(3)F(2) plants from 24 independently derived BC(3) families, we were able to detect 32 and nine quantitative trait loci (QTLs) for fiber fineness and micronaire (MIC), respectively. The discovery of larger numbers of QTLs in this study than previously found in other studies based on F(2) populations grown in favorable environments reflects the ability of the backcross-self design to resolve smaller QTL effects. Although the two measurements differed dramatically in the number of QTLs detected, seven of the nine MIC QTLs were also associated with fiber fineness. This supports other data in suggesting that fiber fineness more accurately reflects the underlying physical properties of cotton fibers and, consequently, is a preferable trait for selection. "Negative transgression," with the majority of BC(3)F(2) families showing average phenotypes that were poorer than that of the inferior parent, suggests that many of the new gene combinations formed by interspecific hybridization are maladaptive and may contribute to the lack of progress in utilizing G. barbadense in conventional breeding programs to improve upland cotton.

Analysis of Variance↗
PubMed2004

Evaluation of fertility and infertility in natural service bulls.

The potential fertility of bulls can be evaluated in the field by assessment of mating ability and physical examination. Both methods are useful for screening out low fertility bulls, although neither allows precise determination of the pregnancy rates that bulls actually achieve. Observations of coitus, libido testing and service capacity testing are the main methods of assessing mating ability in the field and, although not reliable for virgin bulls, are widely used for older bulls. Of the traits that are assessed during physical examination, those most closely correlated with fertility are scrotal circumference and the semen quality parameters of motility and morphology. Whilst these methods allow reasonable accuracy in determining the fertility potential of an individual bull, they do not take into account other managemental constraint to bulls' fertility. Although these are reasonable well understood for beef herds, the managemental factors that affect the performance of natural service sires in dairy herds are poorly understood.

Animals↗
PubMed2006

The role of forensic geoscience in wildlife crime detection.

The increase in both automation and precision in the analysis of geological materials has had significant impact upon forensic investigations in the last 10 years. There is however, a fundamental philosophical difference between forensic and geological enquiry. This paper presents the results of forensic geoscientific investigations of three cases of wildlife crime. Two cases involve the analysis of soils recovered after incidents of illegal badger baiting in the United Kingdom. The third case involves the illegal importation of Eleonora's Falcon (Falco eleonorae) into the United Kingdom from the Mediterranean. All three cases utilise the analysis of soils by a variety of physical, chemical and biological techniques. These involve mineral and grain size analyses, cation and anion compositions, pH, organic content and pollen analysis. The independent analysis undertaken by specialists in each of these three main fields conclude firstly, that there is a significant similarity between sediments taken at the crime site at both badger setts and with sediments recovered from various spades, shovels and clothing belonging to suspects and secondly, that the soils analysed associated with the removal of the falcon eggs in the Mediterranean contained characteristics similar in many respects to the soils of the breeding areas of F. eleonorae on the cliffs of Mallorca. The use of these independent techniques in wildlife crime detection has great potential given the ubiquitous nature of soils and sediments found in association with wildlife sites.

Animals↗
PubMed2003

Bayesian estimation of parameters of a structural model for genetic covariances between milk yield in five regions of the United States.

Inference about genetic covariance matrices using multiple-trait models is often hindered by lack of information. This leads to imprecise estimates of genetic parameters and of breeding values. Patterns in a genetic covariance matrix can be exploited to reduce the number of parameters and to increase quality of inferences. A structural model for genetic covariances was developed and fitted to milk yield data in five regions of the United States. This was compared with a standard multiple-trait analysis using a deviance information criterion, a measure of quality of fit. Data consisted of 3,465,334 Holstein first-lactation records from daughters of 43,755 sires in five regions of the United States (Midwest, Northeast, Northwest, Southeast, Southwest). Parameters of the structural model included an intercept and effects of measures of genetic and of management similarity on genetic covariances. Genetic similarity depended on the number of records contributed by sires that were common to a pair of regions. Management similarity was a function of the quantity of concentrate used to produce 1000 kg of milk in each pair of regions. The structural and the multiple-trait models gave similar estimates of genetic covariances, but the number of parameters was 8 in the former vs. 15 in the latter. Hence, estimates of genetic covariances were more precise with the structural model. A deviance information criterion suggested a slight superiority of the multiple-trait model, although probably within sampling error. For both models, genetic correlations between milk yield in five regions of the United States were larger than 0.93.

Analysis of Variance↗
PubMed2005

The timing of ovulation and insemination schedules in superstimulated cattle.

The development of treatments that control follicular wave dynamics during the bovine estrous cycle has resulted in interesting possibilities for the precise control of follicular wave emergence and the time of ovulation. For superstimulation, follicular wave emergence can be controlled by ultrasound-guided follicle ablation with FSH treatments initiated 1 or 2 d later, or injection of estradiol combined with progesterone at the time of insertion of a progestogen releasing device and FSH treatments beginning 4 d later. These are the most widely used protocols for superstimulation of donor cows because they offer the convenience of being able to initiate treatments quickly and at a self-appointed time, without reducing the number of transferable embryos. However, these protocols still require precise estrus detection of donors following superstimulation in order to conduct AI at the most appropriate time. Recent studies have been designed to develop superstimulation protocols that involve fixed-time AI of donors, without regard to estrus detection. Results presented herein indicate that delaying the removal of a progestogen releasing device, combined with the administration of GnRH or porcine LH (pLH) 12 or 24 h later results in predictable, synchronous ovulations, permitting fixed-time AI without reducing the numbers or quality of embryos. These protocols facilitate the application of on-farm embryo transfer programs because they are practical, easy to administer by farm personnel, and more importantly, they eliminate the need for detecting estrus.

Animals↗