Ovulation and lambing rates in Karaguniki ewes after treatment with follicular fluid

The aim of the present study was to examine the effect of steroid-free bovine follicular fluid (bFF) on both ovulation and lambing rates. For this purpose, 30 adult ewes of the Karaguniki breed were randomly allocated to three treatment groups (A,B and C; n=10 ewes each) during the breeding season of 1988. The ewes in Group A received bFF (6 ml iv) twice daily during their luteal phase, starting on Day 5 and lasting until Day 9. The ewes in Group B received a mixture of bFF/arachid oil (3 ml sc, 2:1) on Days 3, 4, 5, 10 and 12 of the estrous cycle. The ewes in Group C (Controls) were treated subcutanecusly with a mixture of steroid-free bovine plasma and arachid oil (2:1) on the same days as the ewes in Group B. Plasma concentrations of progesterone showed that the luteal function during the treatment cycle was normal in all treated and control ewes. The ovulation and lambing rates, however, were greater in Group A (2.5 +/- 0.2 and 1.9 +/- 0.3, respectively) and in Group B (2.1 +/- 0.2 and 1.6 +/- 0.1, respectively) than in Group C (1.5 +/- 0.2 and 1.2 +/- 0.3, respectively). Precipitating antibodies were detected in the plasma of Group B ewes only.     

Ovulation and embryo recovery rates following immunization of mares against an inhibin alpha-subunit fragment

Six normally cycling mares were immunized 5 times at 3-week intervals with a synthetic porcine inhibin alpha-subunit fragment which had been conjugated to bovine serum albumin and emulsified in Freund's incomplete adjuvant. Immunized mares ovulated a significantly larger (P < 0.01) number of follicles per estrous cycle (2.8 +/- 1.1; range 1 to 8 ovulations) than 14 nonimmunized control mares (1.1 +/- 0.1; range 1 to 2 ovulations). Day-7 embryo recovery rates tended to be higher (P < 0.1) in immunized mares (1.6 +/- 0.5 embryos per flush) than in control mares (0.7 +/- 0.2 embryos per flush). No differences in interovulatory intervals were found between the 2 groups. These results indicate that immunization against inhibin may be useful in inducing development and ovulation of multiple follicles for embryo transfer in the mare.     

Factors affecting pregnancy rates following laparoscopic insemination of 28,447 Merino ewes under commercial conditions: a survey

The results of laparoscopic insemination of 28,447 Australian Merino ewes with semen from 468 rams were used to study factors influencing pregnancy. The overall pregnancy rate was 71.7% (20,423/28,447). Pregnancy rates varied with type of progestagen implant, type and dosage of PMSG, fresh or frozen semen, wool type and number of ewes inseminated per hour. The pregnancy rate (64.6%) obtained with Medroxy-progesterone acetate (MAP) sponges, was significantly (P < 0.01) lower than with Fluorogestone acetate 30 mg (FGA 30; 74.7%) sponges, Fluorogestone acetate 40 mg (FGA 40; 72.1%) sponges, and Controlled Internal Drug Release (CIDR-G; 71.7%) implants. A PMSG dose of 200 IU resulted in significantly (P < 0.05) lower pregnancy rates (62.4%) compared with 250 IU (72.9%), 300 IU (79.1%) and > or = 375 IU (69.4%). The mean pregnancy rate for ewes administered Folligon PMSG was 71.9%, which was significantly higher (P < 0.001) than that of ewes treated with Pregnecol PMSG (65.8%). The use of Pregnecol PMSG and MAP sponges was associated, and thus their conditional effects could not be calculated. Ewes inseminated with fresh semen were significantly (P < 0.001) more likely to become pregnant (82.2%) than those inseminated with semen frozen in pellets (69.5%) or straws (71.6%). Ewes inseminated during the months of March, April or May (fall, 71.5%) were just as likely to become pregnant as those ewes inseminated in November, December, January or February (69.6%). Significantly (P < 0.05) fewer strong wool ewes become pregnant to laparoscopic AI, (67.6%) than fine (71.7%), fine medium (73%) or medium wool ewes. Significantly (P < 0.0001) more pregnancies (77.6%) were achieved when more than 55 ewes were inseminated per hour compared with fewer than 35 ewes per hour (63.4%).     

Ovulation, fertilization and lambing rates, and peripheral progesterone concentrations, in ewes inseminated at a natural oestrus during November or February.

The objective of this study was to determine the relative importance of seasonal changes in ovulation rate, fertilization rate and embryo survival as the cause of reduced lambing rates in ewes mated in February compared with those mated in November. The study was conducted at 57 degrees N using mature Mule ewes and Suffolk rams. Sixty ewes were allocated equally to five groups: unbred (UB) or mated at a natural oestrus during November (N) or February (F) by natural (N) or cervical artificial (A) insemination. Groups were maintained separately at pasture supplemented with hay. A raddled vasectomized or non-vasectomized ram was present with UB, NN and NA groups from 26 October 1995 to 1 January 1996 and with UB, FN and FA groups from 25 January 1996 to 31 March 1996. Ewes marked by the ram were recorded twice a day, and those in groups NN, NA, FN and FA were inseminated at their second behavioural oestrus. For all ewes, blood samples were obtained once a day from introduction of the vasectomized rams until 30 days after mating (groups NN, NA, FN and FA) or 20 days after the first oestrus (group UB), and ovulation rate was measured by laparoscopy 7 days after the first oestrus. For ewes in groups NN, NA, FN and FA, ovulation rate was measured again after the second oestrus and ova were recovered from six ewes per group for assessment of fertilization before autotransfer. Pregnancy and lambing rates were recorded at term. Mean (+/- SE) dates of the first recorded oestrus for ewes in groups NN, NA and UB, and FN, FA and UB were 4 +/- 1.1 November and 4 +/- 0.9 February, respectively, and intervals between the first and second oestrus were 16 +/- 0.2 and 17 +/- 0.3 days (P < 0.01), respectively. Ovulation rates were 2.6 +/- 0.08 and 2.0 +/- 0.05 (P < 0.001), and peripheral progesterone concentrations during the luteal phase were 8.5 +/- 0.25 and 7.6 +/- 0.31 ng ml-1 (P < 0.05), for November and February, respectively. The difference in peripheral progesterone concentration was not solely attributable to the difference in ovulation rate. There was no significant effect of month or method of insemination, or of embryo recovery and autotransfer procedures on pregnancy rates and the proportion of ewes that became pregnant were NN 0.92, NA 0.83, FN 0.67 and FA 0.75. For ewes undergoing embryo recovery and autotransfer, ova recovered per corpus luteum were 1.00, 0.93, 1.00 and 0.92, fertilized ova per ovum recovered were 0.69, 0.92, 1.00 and 0.83, and lambs born per corpus luteum were 0.62, 0.79, 0.78 and 0.58 for NN, NA, FN and FA groups, respectively. There were no significant seasonal effects on fertilization rate or embryo survival. It is concluded that a seasonal decline in ovulation rate is the primary cause of reduced lambing rates in ewes mated in February compared with those mated in November. Pregnancy rates were high after mating in both periods and were not enhanced by the use of cervical insemination.     

Filtering and feeding rates of cyclopoid copepods feeding on phytoplankton

The algal biomass ingested by omnivorous cyclopoid copepods (Cyclops kolensis and C. vicinus) was measured by two methods in the hypertrophic Heiligensee in Berlin (West Germany). The clearance and ingestion rates inferred from measurements of natural populations of ¹⁴C labelled phytoplankton were compared with those obtained from chlorophyll a determinations using the presence/absence method (observed chlorophyll a content of natural lake phytoplankton with and without addition of cyclopoids). Both methods gave similar results. Nevertheless, the radio tracer method is preferred, mainly because the short feeding duration excludes high variations in both the food composition and food concentration that limit the presence/absence method.     

Steroid secretion rates and plasma binding activity in androstenedione-immune ewes with an autotransplanted ovary

Mature Merino ewes in which the left ovary and its vascular pedicle had been autotransplanted to the neck were divided into control (N = 5) and immunized groups (N = 6). The immunized ewes were treated (2 ml s.c.) with Fecundin 1 and 4 weeks before the start of blood sampling. Ovarian and jugular venous blood was collected every 10 min at two stages of the follicular phase (21-27 h and 38-42 h after i.m. injection of 125 micrograms of a prostaglandin (PG) analogue) and during the mid-luteal phase (8 h at 15-min intervals). The ewes were monitored regularly for luteal function and preovulatory LH surges. Hormone concentrations and anti-androstenedione titres were assayed by RIA and ovarian secretion rates of oestradiol-17 beta, progesterone and androstenedione were determined. After the booster immunization, progesterone increased simultaneously with titre in immunized ewes, reaching 30 ng/ml at the time of PG injection when median titre was 1:10,000. All ewes responded to PG with LH surges 42-72 h later: 2 of the immunized ewes then had a second LH surge within 3-4 days at a time when peripheral progesterone values were 2-3 ng/ml. The frequency of steroid and LH pulses was greater in immunized ewes (P less than 0.05) during the luteal phase but not the follicular phase. The secretion rate of androstenedione was 6-10 times greater (19-37 ng/min; P less than 0.001) in immunized ewes at all sampling stages. Progesterone secretion rates were 3 times greater (16 micrograms/min; P less than 0.001) during the luteal phase in immunized ewes. The amplitude of oestradiol pulses was significantly reduced in immunized ewes (4.8 vs 2.1 ng/min at +24 h and 6.5 vs 2.8 ng/min at +40 h in control and immunized ewes, respectively: P less than 0.05) during the follicular phase. However, the mean secretion rate of oestradiol at each phase of the cycle was not significantly different between treatment groups. Analysis of bound and free steroid using polyethylene glycol showed that greater than 98% of peripheral and ovarian venous androstenedione and 86% of peripheral progesterone was bound in immunized ewes but there was no appreciable binding (less than 0.1%) in control ewes. Similarly, 50% of ovarian venous oestradiol was bound in immunized ewes compared to 15% in control ewes. We conclude that immunization against androstenedione increases the secretion rate of androstenedione and progesterone but not of oestradiol.(ABSTRACT TRUNCATED AT 400 WORDS)     

Fluid intake rates in ants correlate with their feeding habits

This study investigates the techniques of nectar feeding in 11 different ant species, and quantitatively compares fluid intake rates over a wide range of nectar concentrations in four species that largely differ in their feeding habits. Ants were observed to employ two different techniques for liquid food intake, in which the glossa works either as a passive duct-like structure (sucking), or as an up- and downwards moving shovel (licking). The technique employed for collecting fluids at ad libitum food sources was observed to be species-specific and to correlate with the presence or absence of a well-developed crop in the species under scrutiny. Workers of ponerine ants licked fluid food during foraging and transported it as a droplet between their mandibles, whereas workers of species belonging to phylogenetically more advanced subfamilies, with a crop capable of storing liquids, sucked the fluid food, such as formicine ants of the genus Camponotus. In order to evaluate the performance of fluid collection during foraging, intake rates for sucrose solutions of different concentrations were measured in four ant species that differ in their foraging ecology. Scaling functions between fluid intake rates and ant size were first established for the polymorphic species, so as to compare ants of different size across species. Results showed that fluid intake rate depended, as expected and previously reported in the literature, on sugar concentration and the associated fluid viscosity. It also depended on both the species-specific feeding technique and the extent of specialization on foraging on liquid food. For similarly-sized ants, workers of two nectar-feeding ant species, Camponotus rufipes (Formicinae) and Pachycondyla villosa (Ponerinae), collected fluids with the highest intake rates, while workers of the leaf-cutting ant Atta sexdens (Myrmicinae) and a predatory ant from the Rhytidoponera impressa-complex (Ponerinae) did so with the lowest rate. Calculating the energy intake rates in mg sucrose per unit time, licking was shown to be a more advantageous technique at higher sugar concentrations than sucking, whereas sucking provided a higher energy intake rate at lower sugar concentrations.     

Follicular and FSH dynamics in ewes with a history of high and low ovulation rates

Daily transrectal ultrasound scanning and twice-daily blood sampling were used to monitor the temporal relationships between FSH concentrations and follicle development during complete interovulatory intervals for ewes in which the ovulation rate in each of the 2 previous years was high or low (> or = 3 and < or = 2 ovulations, respectively). Follicles that reached > or = 5 mm were used to define a follicular wave and were tracked retrospectively to 3 mm (emergence). The hypothesis that FSH surges (identified with a computer program) and follicular waves (retrospectively determined based on ultrasound scanning) are temporally associated was supported in both groups by the emergence of an anovulatory or ovulatory follicular wave near the peak of an FSH surge. Further support for the hypothesis was a significant increase in FSH concentrations before and a significant decrease after follicular-wave emergence in both groups independent of the identification of FSH surges. Ewes with a history of high ovulation rates had smaller follicles (anovulatory and ovulatory) and more ovulations, but the 2 groups were similar in the number of ovulatory follicular waves and associated FSH surges, number and characteristics of the FSH surges, and mean FSH concentrations per interovulatory interval. Surges of FSH were periodic (every 3 or 4 d) regardless of the ovulation-rate group or follicle response. In ewes with a low ovulation rate, the nonovulatory FSH surges were most frequently associated with emergence of detected anovulatory follicular waves. In ewes with a high ovulation rate, more FSH surges were not associated with a detected follicular wave, as defined, presumably because the largest follicle did not reach 5 mm. The results indicated that the factors resulting in a high ovulation rate were not exerted through circulatory patterns or concentrations of FSH but involved a shorter growth phase and smaller maximal diameter of follicles.     

Ovulation rate and embryo survival in Damline ewes after treatment with bovine follicular fluid in the luteal phase of the oestrous cycle

Treatment of Damline ewes with twice daily i.v. injections of bovine follicular fluid during the luteal phase for 10, 6 or 2 days before prostaglandin-induced luteolysis resulted in an increase in ovulation rate. This was associated with a large rebound increase in plasma concentrations of FSH after the last injection of bovine follicular fluid. While conception rate was not affected by bovine follicular fluid treatment, a higher percentage embryonic loss was observed between Days 3 and 34 of pregnancy in the 10-day treatment group only compared to controls. This reflected the increase in ovulation rate above the optimum for embryonic survival in this breed. The present results suggest that the increase in ovulation rate induced by bovine follicular fluid treatment in the luteal phase of the cycle before mating would result in a significant increase in the number of lambs born.     

Ovulation level and prolificacy in ewes depending on their age, birth type and percentage of prolific genotype

During December mating periods of 2000-2003, wool and meat breeds crossed with East Friesian milk sheep and rams of prolific breeds (Finn or Romanov) were examined laparoscopically. Ovine ovaries were examined between 4 and 9 days after mating. The litter size was recorded and compared with the number of ovulations. The fertility of the analyzed animals was 69.6%, with 192.6% prolificacy. The difference between the average number of corpora lutea found on ovaries and the mean number of lambs born was 0.35 and ranged from 0.32 to 0.41 according to age group, from 0.22 to 0.41 according to sheep birth type, and from 0 to 0.52 lamb per ewe according to percentage of prolific breeds.     

Total follicular populations in ewes of high and low ovulation rates.

The total ovarian follicular populations were studied in two breeds of ewes which differed greatly in their ovulation rates. Thus 8 Romanov (mean ovulation rate 3.1) and 12 Ile-de-France ewes (mean ovulation rate 1.4) were ovariectomized at oestrus during the breeding season. Each right ovary and 3 left ovaries were sectioned at 7 micron and examined microscopically. The number of small follicles, i.e. with 2 or less layers of granulosa cells, was estimated by a tested sampling procedure whilst all larger follicles were measured and arranged into classes. There were half as many small follicles but 1.5--2 times more large follicles in the ovaries of the Romanov ewes compared to those of the Ile-de-France ewes. The number of atretic follicles was approximately the same in both breeds and does not explain the difference observed in ovulation rate. It is concluded that the higher ovulation rate in the Romanov ewe is due to the greater number of large follicles available to be stimulated for ovulation.     

Universal temperature and body-mass scaling of feeding rates

Knowledge of feeding rates is the basis to understand interaction strength and subsequently the stability of ecosystems and biodiversity. Feeding rates, as all biological rates, depend on consumer and resource body masses and environmental temperature. Despite five decades of research on functional responses as quantitative models of feeding rates, a unifying framework of how they scale with body masses and temperature is still lacking. This is perplexing, considering that the strength of functional responses (i.e. interaction strengths) is crucially important for the stability of simple consumer–resource systems and the persistence, sustainability and biodiversity of complex communities. Here, we present the largest currently available database on functional response parameters and their scaling with body mass and temperature. Moreover, these data are integrated across ecosystems and metabolic types of species. Surprisingly, we found general temperature dependencies that differed from the Arrhenius terms predicted by metabolic models. Additionally, the body-mass-scaling relationships were more complex than expected and differed across ecosystems and metabolic types. At local scales (taxonomically narrow groups of consumer–resource pairs), we found hump-shaped deviations from the temperature and body-mass-scaling relationships. Despite the complexity of our results, these body-mass- and temperature-scaling models remain useful as a mechanistic basis for predicting the consequences of warming for interaction strengths, population dynamics and network stability across communities differing in their size structure.     

Uncontrolled admixture and loss of genetic diversity in a local Vietnamese pig breed

The expansion of intensive livestock production systems in developing countries has increased the introduction of highly productive exotic breeds facilitating indiscriminate crossbreeding with local breeds. In this study, we set out to investigate the genetic status of the Vietnamese Black H'mong pig breed by evaluating (1) genetic diversity and (2) introgression from exotic breeds. Two exotic breeds, namely Landrace and Yorkshire used for crossbreeding, and the H'mong pig population from Ha Giang (HG) province were investigated using microsatellite markers. Within the province, three phenotypes were observed: a White, a Spotted and a Black phenotype. Genetic differentiation between phenotypes was low (0.5-6.1%). The White phenotypes showed intermediate admixture values between exotic breeds and the Black HG population (0.53), indicating a crossbreed status. Management practices were used to predict the rate of private diversity loss due to exotic gene introgressions. After 60 generations, 100% of Black private alleles will be lost. This loss is accelerated if the admixture rate is increased but can be slowed down if the mortality rate (e.g., recruitment rate) is decreased. Our study showed that a large number of markers are needed for accurately identifying hybrid classes for closely related populations. While our estimate of admixture still seems underestimated, genetic erosion can occur very fast even through indiscriminate crossbreeding.     

Freemartinism and FecX allele determination in replacement ewes of the Rasa Aragonesa sheep breed by duplex PCR

A new naturally occurring mutation in the fecundity gene BMP15 in the Rasa Aragonesa sheep breed (Ovis aries) has been found to affect prolificacy. This mutation (FecX^R allele) is a deletion of 17 base pairs that leads to an altered amino acid sequence, and this alteration increases prolificacy in heterozygous ewes but causes sterility in homozygous ewes. Selection of repository lambs with the FecX^R allele increases rates of twins and multiple lambing and thereby also increases the probability of lambing freemartins that will become sterile. In this sense, an accurate, reliable, and quick method was developed by duplex polymerase chain reaction (PCR) for sex, amplifying an ovine-specific Y chromosome repetitive fragment, and BMP15 genotype determination in replacement ewe lambs. The BMP15 fragment served as an internal control of the amplification and detected the FecX^R allele, avoiding a false negative and then a mistake in freemartin detection. This assay uncovered 6 freemartin females among 195 replacement ewes from 7 different commercial flocks and 1 experimental flock. Furthermore, 1554 rams from 64 commercial flocks were also analyzed to identify FecX^R rams. This analysis identified 103 rams hemizygous for the FecX^R allele and 1 heterozygous ram. Because this gene is located on the X chromosome, this heterozygous animal is a freemartin ram that is co-amplifying the DNA from XX and XY lymphocytes. These results confirm the usefulness of this multiplex PCR assay for detecting phenotypically sexed females, freemartins, and the BMP15 genotype to detect highly prolific ewes in commercial flocks and to assist breeders in selection of repository lambs.     

Ultrasonic study of follicular dynamics following superovulation in German Merino ewes

Ewes are commonly superovulated with a single dose of eCG or multiple doses of pFSH. It would be convenient and less expensive to use a single dose of FSH, but results of various trials have been controversial. We wished to investigate ovarian dynamics using ultrasonography after superovulation with a single dose of pFSH and hMG as compared with a single dose of eCG. Estrus was synchronized during the breeding season with fluorogestone acetate-containing intravaginal sponges in adult German Merino ewes (n = 38). They were superovulated with single doses of pFSH (17 mg; n = 10), hMG (600 IU FSH and 600 IU LH; n = 9) or eCG (1250 IU; n = 10) given at the time of sponge removal, or pFSH (17 mg; n = 9) given 36h before sponge removal. Follicular and luteal development were observed by ultrasonic scanning every 8 h from the gonadotrophin injection until the end of estrus, and then once daily until Day 6 after estrus. Jugular venous blood was collected starting immediately before and 1 h after superovulation treatment, then twice daily until the end of estrus and once daily for the following 7 days. Concentrations of estradiol-17beta (E2) and progesterone (P4) were measured in plasma. Differences in the follicular dynamics of the 4 superovulation groups were obvious. The functional duration of the pFSH action was estimated to last approximately 48 h, whereas eCG and hMG were active for up to 72 h. The diameter of the ovulatory follicles proved to be smaller than it was described for unstimulated ewes. Single applications of pFSH or hMG can induce a superovulatory response, although the post-estrus progesterone profile revealed a high premature luteal regression rate in the different superovulation groups. Premature corpus luteum regression could not be seen by ultrasonography at this early stage of the luteal phase, indicating that the technique may fail to detect these corpora lutea in an embryo transfer program. However, ultrasonography represents a suitable method to observe follicular dynamics following different superovulation regimens in sheep.     

SYMMETREE: whole-tree analysis of differential diversification rates

SymmeTREE implements several tests of differential diversification rates that exploit information on the topological distribution of species diversity throughout entire trees to address two general questions: (1) Has a given tree experienced significant variation in diversification rates among its branches? and (2) If so, along which branches have significant shifts in diversification rate occurred? These explicitly model-based methods are robust to uncertainty in estimates of branch length/duration and can accommodate incompletely resolved trees and other forms of phylogenetic uncertainty. AVAILABILITY: http://www.phylodiversity.net/bmoore/software.html CONTACT: brian.moore@yale.edu.     

Inferring gene regulatory networks using differential evolution with local search heuristics

We present a memetic algorithm for evolving the structure of biomolecular interactions and inferring the effective kinetic parameters from the time series data of gene expression using the decoupled Ssystem formalism. We propose an Information Criteria based fitness evaluation for gene network model selection instead of the conventional Mean Squared Error (MSE) based fitness evaluation. A hill-climbing local-search method has been incorporated in our evolutionary algorithm for efficiently attaining the skeletal architecture which is most frequently observed in biological networks. The suitability of the method is tested in gene circuit reconstruction experiments, varying the network dimension and/or characteristics, the amount of gene expression data used for inference and the noise level present in expression profiles. The reconstruction method inferred the network topology and the regulatory parameters with high accuracy. Nevertheless, the performance is limited to the amount of expression data used and the noise level present in the data. The proposed fitness function has been found more suitable for identifying correct network topology and for estimating the accurate parameter values compared to the existing ones. Finally, we applied the methodology for analyzing the cell-cycle gene expression data of budding yeast and reconstructed the network of some key regulators.