Difference In Conception Rate Research Articles

Comparison of sperm parameters and fertility between sperm cryopreserved from ejaculated semen and from the epididymis of subfertile stallions

Despite the benefits provided by seminal plasma during natural cover, its function is questionable when a biotechnology such artificial insemination is used. Studies employing spermatozoa from the cauda epididymis with or without the addition of seminal plasma showed no difference in conception rates. Furthermore, studies have reported deleterious effects of secretions from accessory glands on sperm viability and conception rate (Aurich et al., Theriogenology, 1996; 46, 791-797), especially in stallions with poor semen quality. Thus the aims of this study were: 1) compare the sperm kinetic parameters, viability and fertility of sperm recovered from the ejaculate (G1) and from the cauda epididymis (G2) of subfertile stallions (pregnancy rate<35%). For G1, one ejaculate from each of eight subfertile stallions was collected and then subjected to cryopreservation using the extender BotuCrioTM. One week after the last semen collection, the stallions underwent bilateral orchiectomy. Sperm from the cauda epididymis were harvested immediately after castration by retrograde flushing the caudal portion (G2) of the epididymis using a skim milk-based extender (BotuSemenTM). The recovered sperm were then cryopreserved using BotuCrioTM extender. The sperm samples were analyzed for kinetic parameters by computer-assisted analyses (CASAHTM-IVOS) and plasma membrane integrity (Propidium iodide, Sigma; Hoechst 33345, Sigma), acrosome integrity (FITC-PSA, Sigma; Hoechst 33345, Sigma) and degree of translocation of phosphatidylserine (Annexin-V–APC, Pharmingen; Hoechst 33345, Sigma) by flow cytometry (BD-LSRFortessa ). For analysis, straws were thawed in a 46 C water bath for 20 sec. Artificial insemination was performed in the tip of the uterine horn ipsilateral to

Treatment protocol with progesterone, estradiol and oxytocin to improve conception rate and allows for early diagnosis of pregnancy in Black Bengal goat

This work was performed to develop a treatment protocol that will shorten the length of estrous cycle in mated goats those fail to conceive, without reduction in conception rate. In experiment 1, ninety goats (single parity, 1½ to 2 years age) were divided into nine groups of ten goats each. On return to heat, all groups were mated barring groups 1, 3 and 4. On days 3-5 of estrous, progesterone was treated at the dose rate of 10 mg i.m (groups 3, 5 and 7) or 30 mg i.m. (groups 4, 6 and 8). Groups 7, 8 and 9 received estradiol (500 µg i.m.; day 8) + oxytocin (10 IU i.m.; day 9) treatment. Following treatments, the goats were observed for heat and appearance of embryonic vescicles (EV) by transabdominal ultrasonography. In experiment 2, group 2 (n=50) was equal to group 8 of experiment 1 and group 1 (n=50) served as control. The litter size and weight was recorded at birth. Early progesterone treatment significantly (P<0.05) shortened the cycle length in groups 3 (day 15) and 4 (day 17) respectively compared to control (group 1; 21 days), whereas mated group 5 and 6 did not have any difference in conception rate compared to control (group 2). In does of group 5 & 6, EVs were observed much earlier than group 2. Estradiol + oxytocin treatment had no effect on conception rate of group 8, while does of group 7 and 9 returned to heat on day 12. In experiment 2, significant difference in conception rate and percentage of single, double, triplet and quadruplet born was observed between control and treated groups while the mean litter weight born was non-significant. Thus early pregnancy diagnosis can be done at by progesterone + estrogen treatment that not only shortens the length of estrous cycle, if the animals fail to conceive, but also improves the conception rate.

The Quality of Cryopreserved Sperm Collected from Feline Caudal Epididymides Using Seminal Plasma

It is thought that differences in conception rate between feline epididymal sperm and ejaculate sperm occur because, unlike ejaculated sperm, caudal epididymal sperm have not been sensitized with seminal plasma (SP). In this study, we investigated whether collection of feline epididymal sperm with SP influences sperm qualities after freezing-thawing. Sperm were sensitized with SP for 10 min at room temperature. As a result, the motility of caudal epididymal sperm sensitized with SP immediately after collection was significantly lower than that of ejaculate sperm, and no difference was noted in sperm qualities after freezing-thawing. This shows that the qualities of caudal epididymal sperm cannot be improved to a level higher than those of ejaculate sperm by sensitization with SP.

243 APOPTOTIC-LIKE CHANGES AND FERTILITY OF TRANSGENIC FOR HUMAN α1,2-FUCOSYLTRANSFERASE GENE AND NONTRANSGENIC BOAR SPERMATOZOA

In the current study, we used sperm from transgenic boars with a gene construct containing the human α1,2-fucosyltransferase gene that competes with α1,3-galactosyltransferase for the same substrate, N-acetyl lactose amine. A decreased affinity of the anti-Gal antibodies between the human and the pig can reduce the species-specific immunological difference and reduce the risk of xenographic rejection. The objectives of this research were first to find out if the presence of the human α1,2-fucosyltransferase gene (pCMVFUT gene construct) in boars leads to apoptotic-like changes in the ejaculated spermatozoa, and second, to verify the fertilizing capacity of the sperm from transgenic (TG) boars. Six ejaculates were collected from 5 TG and 5 nontransgenic (NTG) boars, both crossbreds of Polish Landrace and Large White aged 21.3 ± 0.8 months. Only ejaculates with at least 70% motile and 80% morphologically normal sperm were used. Fresh semen were diluted to a final concentration of 2.5 × 109 sperm mL–1 in Biosolwens Plus (Biochefa, Sosnowiec, Poland) extender and used for artificial insemination of gilts (5 gilts per 1 ejaculate). All ejaculates were analysed on the day of insemination using 2 fluorescence methods: an assay to assess the early changes in sperm membrane integrity using the combination of fluorophores YO-PRO-1 and propidium iodide (PI; Molecular Probes Inc., Eugene, OR, USA) and an assay for phosphatidylserine (PS) translocation across the plasma membranes using Annexin-V–fluorescein isothiocyanate (FITC) and PI (Roche, Mannheim, Germany). Fluorescent staining was measured by microscopic observation of at least 200 spermatozoa/sample per slide. Results are expressed as means ± SD. Significance of the differences between means was tested by Student’s t-test. Using the YO-PRO-1/PI assay, we observed 3 groups of sperm: apoptotic sperm (3.1 ± 1.5% v. 3.5 ± 1.6%), necrotic sperm (22.2 ± 5.3% v. 19.7 ± 5.1%), and live sperm (74.7 ± 7.8% v. 76.8 ± 5.6%) in TG and NTG boar semen, respectively. Using the Annexin-V–FITC/PI assay, 4 subpopulations were detectable: early apoptotic sperm (2.3 ± 1.3% v. 2.6 ± 1.5%), late apoptotic/early necrotic (16.9 ± 8.4% v. 15.7 ± 5.6%), necrotic sperm (7.7 ± 3.9% v. 6.2 ± 2.9%), and live sperm (73.1 ± 6.1% v. 75.5 ± 5.8%) in TG and NTG boar semen, respectively. The use of both assays yielded no significant differences (P ≥ 0.05) in all detected subpopulations of sperm of TG boars compared with that of NTG boars. Moreover, no differences in conception rate (87.7 and 83.8%) and in the average number of live-born piglets per litter (10.7 and 11.2) were observed after insemination using the semen from TG and NTG boars, respectively. In conclusion, the presence of human α1,2-fucosyltransferase gene in the genome of TG boars did not increase apoptotic-like changes in sperm and did not affect pregnancy rate or litter size. This work was supported by Grant NR 12 0036 06 from the National Centre of Research and Development, Poland.

Efficiency of two timed artificial insemination protocols in Murrah buffaloes managed under a semi-intensive system in the tropics

The objective of the study was to determine the efficiency of ovsynch (OV) versus presynch-ovsynch (P-OV) protocol for synchronization of ovulation and timed artificial insemination (TAI) in female buffaloes. The OV group (n = 40) received gonadotrophin-releasing hormone (GnRH) on day 0 (random day of the estrous cycle), prostaglandin PGF₂α on day 7 and a second GnRH administration on day 9 followed by a single artificial insemination (AI) 16-20 h later. The P-OV group (n = 40) received two PGF₂α injections 14 days apart, with the second injection administered 14 days before starting the OV protocol. Progesterone (P(4)) was measured at the time of PGF₂α administration (within the OV protocol) and AI. Neither ovulation rate ((24 h after TAI) OV 90%-36/40 vs. P-OV 85%-34/40) nor pregnancy rates ((day 60 after TAI) OV 35%-14/40 vs. P-OV 45%-18/40) differed between the two protocols. Pregnant buffaloes had lower concentrations of P(4) at AI compared with non-pregnant animals in the OV group (0.7 +/- 0.1 vs. 1.1 +/- 0.1 ng/ml); but in the P-OV group, differences did not reach statistical significance (0.8 +/- 0.1 vs. 1.0 +/- 0.1 ng/ml). This apparent trend reached statistical significance when the analysis was carried out in animals from both protocols (0.7 +/- 0.1 (pregnant) vs. 1.1 +/- 0.1 (non-pregnant) ng/ml). In conclusion, both protocols synchronize ovulation effectively with no significant differences in conception rates. High concentrations of P(4) at AI seem to be detrimental for the establishment of pregnancy in lactating buffalo cows.

Changes in Conception Rate, Calving Performance, and Calf Health and Survival From the Use of Crossbred Jersey × Holstein Sires as Mates for Holstein Dams

Differences in conception rates in matings of Holstein sires or F1 Jersey×Holstein sires to Holstein dams in the University of Wisconsin–Madison experimental herd were evaluated, as were differences in birth weight, dystocia, serum protein, serum IgG, fecal consistency, respiratory disease, and perinatal and pre-weaning mortality among the resulting calves. When mated to randomly chosen, lactating Holstein cows, Holstein sires (n = 74) and crossbred sires (n = 7) did not differ in male fertility. Calves from Holstein sires and multiparous Holstein dams (n = 99) were 1.9kg heavier than calves from crossbred sires and multiparous Holstein dams (n = 211), leading to greater likelihood (odds ratio of 1.24) of dystocia. Furthermore, calves from crossbred sires and multiparous Holstein dams had higher serum protein and serum IgG levels between 24 and 72h of age, as well as lower rates of perinatal and preweaning morality than calves from Holstein sires and multiparous or primiparous Holstein dams. Mean fecal consistency scores from birth to 7 d of age and number of days with scours also tended to be lower among calves from crossbred sires, compared with calves from Holstein sires. No differences were observed in the incidence or severity of respiratory disease. Results of this study suggest that introduction of Jersey genes via crossbreeding may lead to a reduction in dystocia and improvements in calf health and survival in Holstein herds. Future studies should address other traits related to dairy farm profitability, including milk composition, female fertility, longevity, feed efficiency, and resistance to infectious and metabolic diseases.

214 EFFECT OF TIMING OF PGF, eCG, AND ESTRADIOL BENZOATE IN RECIPIENTS SYNCHRONIZED WITH A PROGESTIN-BASED PROTOCOL FOR FIXED-TIME EMBRYO TRANSFER

An experiment was designed to evaluate alternative treatment protocols for fixed-time embryo transfer (FTET) in recipients in order to reduce cattle handling. Non-lactating, cycling Bos taurus � Bos indicus beef cows (n = 918), with a body condition score (BCS) of 2.5 to 3.5 out of 5, received a progesterone-releasing device (DIB; Syntex, Buenos Aires, Argentina) and 2 mg estradiol benzoate (EB; Syntex) IM on random days of the cycle (Day 0); DIB were removed on Day 8. Cows were placed randomly into 6 treatment groups in a 3 � 2 factorial design. The factors evaluated were time of administration of PGF and eCG [control treatment: PGF Day 5 and eCG Day 5 (Bo et al. 2002 Theriogenology 57, 53–72); PGF Days 0 and 8 and eCG Day 5; PGF Days 0 and 8 and eCG Day 8] and the time of administration of the second injection of EB (at DIB removal or 24 h later). Therefore, cows in the control treatment received 150 �g of d-Cloprostenol (PGF, Ciclase; Syntex) and 400 IU eCG (Novormon; Syntex) on Day 5, whereas cows in the other 2 treatments received 75 �g of PGF on Days 0 and 8 and 400 IU eCG on either Day 5 or Day 8. Each treatment group was further subdivided to receive 1 mg EB IM on either Day 8 (EB Day 8) or Day 9 (EB Day 9). All recipients, whether observed in estrus or not and with more than one CL with luteal area (total CL area minus cavity area) &amp;gt;76 mm2 on the day before embryo transfer, received frozen-thawed embryos (IETS Grade 1) on Day 16 (EB Day 8) or Day 17 (EB Day 9) by direct transfer. Pregnancy was determined by ultrasonography 30 days after FTET. Continuous data were analyzed by ANOVA and pregnancy rates were analyzed by logistic regression. No effects of body condition score or technician were detected (P &amp;gt; 0.1). Although there were no differences in conception rates between recipients treated with EB on Day 8 or Day 9 (168/321, 52.3% vs. 203/350, 58.0%, respectively; P &amp;gt; 0.1), treatment with EB on Day 8 resulted in fewer recipients selected/treated (321/460, 69.7% vs. 350/458, 76.4%; P &amp;lt; 0.05) and pregnant/treated (168/460, 36.5% vs. 203/458, 44.3%; P &amp;lt; 0.05) than 24 h later (EB Day 9), respectively. The mean interval from DIB removal to estrus was shorter (P &amp;lt; 0.05) for recipients in the EB Day 8 (28.1 � 7.2 h) than in the EB Day 9 (43.5 � 9.4 h) group, and the mean (� SEM) CL area was also less in the EB Day 8 group than in the EB Day 9 group (261.7 � 96.7 vs. 293.1 � 114. mm2; P &amp;lt; 0.05). The number of recipients selected/treated was higher in the group receiving PGF on Days 0 and 8 and eCG on Day 8 (243/305, 79.6%) than in the group receiving PGF on Days 0 and 8 and eCG on Day 5 (208/301, 69.1%) or the control group (220/312, 70.5%). Although the luteal area was greater (P &amp;lt; 0.05) in the PGF on Days 0 and 8 and eCG on Day 5 group (304.4 � 127.1 mm2) than in the groups receiving PGF and eCG on Day 5 (274.6 � 98.6 mm2) or PGF on Days 0 and 8 and eCG Day 8 (258.4 � 90.2 mm2), pregnancy rates did not differ between PGF and eCG treatment groups (P &amp;gt; 0.05). It was concluded that it may be possible to reduce animal handling by treating recipients with a half dose of PGF at the time of DIB insertion and removal, when eCG is also administered, without compromising pregnancy rates.

Performance of mouse lines divergently selected for heat loss when exposed to different environmental temperatures. I. Reproductive performance, pup survival, and metabolic hormones.

Mouse populations differing in metabolic rate have been developed through selection for high (MH) and low (ML) heat loss, along with the unselected controls (MC). Objectives of the study were to compare the MH, ML, and MC lines for reproductive performance, pup survival, and metabolic hormones when reared at 12, 22, and 31 degrees C, and to search for line x environment interactions. Conception and litter size were recorded on the parent generation mice introduced to the environments at 11 wk of age and bred after a 3-wk acclimatization period. Survival of pups (preweaning to 3 wk; postweaning from 3 to 9 wk of age) was measured with continuous exposure in the designated environment from birth to the time of measurement. Corticosterone, triiodothyronine (T3), and thyroxine (T4) serum concentrations were measured on the parent generation after producing litters and on the pup generation at 9 wk. No line x environment interaction was detected for conception rate, preweaning mortality, postweaning survival, pup weaning weight, or body temperature. There were no differences in conception rate among lines and environments. Environments affected survival of pups, but there were no line differences. Rectal body temperatures were greater for MH than ML mice, and MC mice were intermediate; body temperature of mice did not differ among the environments. Lines differed significantly in litter size only in the 22 degrees C environment. No significant line differences were found for serum corticosterone or serum T3 or T4. Line x environment interaction was detected only for litter size and for serum corticosterone concentration in dams. Contrary to the other two lines, ML dam performance relative to MH and MC was not affected negatively by either of the thermal environments. Results from this study do not raise concern that selection to decrease maintenance requirements will produce livestock with any greater liability to cope and perform under an array of environmental temperatures.

Supplementing previously treated anestrous dairy cows with progesterone does not increase first-service conception rate

The objective of this study was to investigate the effect of supplementing previously treated anovulatory anestrous (AA) dairy cows with progesterone delivered intra-vaginally for 7 days, commencing 4 or 5 days after insemination, on first-service conception rate. A clinical trial, involving 990 AA dairy cows in 14 dairy herds, was conducted during the 2002/2003 breeding season. On Day −8, all cows were treated with a progesterone-containing intravaginal device (Cue-Mate ®). The devices were removed on Day −2; on Day −1, all cows were given 1 mg of estradiol benzoate im. Cows in the control group ( n = 499) received no further treatments. Cows in the treatment group ( n = 491) that had been inseminated on Day 0 or 1 had a new device inserted (on Day 4 or 5), with removal of the device after 7 days. First-service conception rates for the control and treatment groups were not different (35.0% versus 36.7% respectively; P = 0.41). Furthermore, there was no difference in conception rates between cows that had devices inserted on Day 4 or 5 (31.3% versus 37.2% respectively; P = 0.45). In conclusion, supplementation of previously treated AA dairy cows with an intravaginal progesterone-releasing device for 7 days (commencing 4 or 5 days after insemination) did not significantly improve first-service conception rate.

21DEEP UTERO-TUBAL SEMEN DEPOSITION IN MEDITERRANEAN ITALIAN BUFFALOES USING A NEW ARTIFICIAL INSEMINATION DEVICE

The use of AI in the buffalo species is still marginal due to traditional lower conception rates when compared to cattle. However recently a number of studies in this field have revealed a promising increase in the efficiency of synchronization protocols for AI linked to more acceptable pregnancy rates. The possibility of using lower spermatozoa concentration of high quality buffalo bulls for AI without reduction in pregnancy outcome can be an additional offset, especially if such spermatozoa can be sexed and used for better reproductive management in buffalo farms. Within this conceptual framework, a new artificial insemination device for semen deposition near the utero-tubal junction (UTJ) in cattle (Ghent device), developed at the University of Ghent (Belgium), has been used in this study. The Ghent device is made of disposable materials and consists of 2 hollow plastic tubes, wherein a catheter filled with semen is introduced. The outer tube is completely rigid, while the inner tube consists of a rigid caudal end and a flexible cranial tip. The outer plastic tube can move independently from the inner tube. Once the insemination device is introduced into the uterine body, the inner tube with its flexible tip is moved forward. The flexible tip makes it possible to follow the curvature of the contractile uterus of the estrous cow, but excludes the use of Cassou straws. The semen is then expelled from the catheter by means of 0.1mL of air followed by 0.6mL of physiological saline solution. To assess the efficacy of the new Ghent device, 67 buffalo cows (Bubalus bubalis) were inseminated during a field trial. Two different insemination methods were used: (1) insemination with the conventional insemination device in the uterine body, and (2) insemination with the Ghent device near the utero-tubal junction ipsi-lateral to the site of ovulation. Artificial insemination was performed twice at 72 and 96hrs after administration of prostaglandins to buffaloes bearing a functional corpus luteum as recorded during ultrasound monitoring. Conventional inseminations were performed with full (16–20×106) and half (8–10×106) insemination doses of frozen-thawed semen, while UTJ-inseminations were performed with full, half and quarter (4–5×106) insemination doses. When inseminations were performed with the conventional insemination device, halving the insemination dose resulted in a non-significant decrease of conception rates from 53% (8/15) to 42% (8/19). However, no difference in conception rates was observed when UTJ-inseminations were performed with a full, half or quarter standard insemination dose: 50% (6/12), 45% (5/11) and 50% (5/10), respectively. Despite the limited number of inseminations performed, this preliminary field trial demonstrates that the Ghent device is suitable for the insemination of buffaloes under field conditions, and that UTJ inseminations can be performed with only one-fourth of the standard insemination dose without a reduction in conception rates.

Prolonging the MGA-prostaglandin F 2α interval from 17 to 19 days in an estrus synchronization system for heifers

Our objective was to determine whether extending the interval from 17 to 19 d between removal of melengestrol acetate (MGA) feed and administration of PGF 2α would alter conception rates, pregnancy rates and the degree of synchrony in replacement beef heifers. A commercial heifer operation in north-central Kansas purchased 591 Angus × Hereford heifers from 12 sources. Prior to the spring breeding season, 14% of the heifers were culled. The remaining heifers were assigned randomly to 2 MGA-PGF 2α synchronization systems. All heifers were fed MGA (0.5 mg/head/d) for 14 d, and PGF 2α was administered either 17 or 19 d after the completion of MGA feeding. Heifers were inseminated artificially for 30 d followed by 30 d of natural mating. Based on each source, first-service conception rates ranged from 66 to 90%, whereas overall pregnancy rates ranged from 91 to 100%. Heifers given PGF 2α on Day 17 after MGA had first-service conception rates of 75.9% compared with 81.4% for heifers receiving PGF 2α on Day 19. In response to the PGF 2α injection, 99% of the Day 19 heifers that were detected in estrus were inseminated artificially by 72 h after the PGF 2α injection, whereas 74% of the heifers in the Day 17 treatment were inseminated by that time. Average interval to artificial insemination (AI) after PGF 2α was greater (P < 0.01) for the Day 17 heifers (73.1 ± 1.1 h) than for the Day 19 heifers (56.2 ± 1.1 h). No differences in conception rates or overall pregnancy rates occurred; however, heifers receiving PGF 2α on Day 19 after MGA had shorter intervals to estrus, and a greater proportion was inseminated within 72 h after PGF 2α, thus possibly facilitating successful timed insemination of the remaining heifers not yet inseminated by that time.

Influence of bacterial vaginosis on conception and miscarriage in the first trimester: cohort study

Objectives: To assess whether bacterial vaginosis affects the rates of conception and miscarriage in the first trimester.Design: Cohort study.Setting: Assisted conception unit of a teaching hospital in Leeds.Participants: 867 consecutive...

Factors affecting reproductive performance in Ontario dairy herds

Data were collected on reproductive, health and production events in 45 dairy herds in southwestern and eastern Ontario, Canada, from July 1990 to July 1993. Mean and median days in milk at first estrus, at first service, and at conception were 85.1 and 83.9, 94.0 and 88.9, and 126.3 and 115.5 d, respectively. The mean estrus detection rate was 48.3%, with a minimum of 28.4% and a maximum of 64.2%. The mean overall conception rate was 46.7%, with a minimum of 29.8% and a maximum of 70.7%. The most commonly used used therapeutic agents were GnRH (11.5% lactational incidence risk) and PG (13.1% lactational incidence risk). Estrus management accounted for the largest portion of PG use in the herds studied (69.4%). Results of a two sample t-test indicated no significant difference in reproductive performance among herds housed in free-stall compared with those housed in tie-stall barns. Multivariate linear regression models of 3 reproductive performance measures indicated that cows with ovarian cysts and/or increased peak milk production had significantly longer calving-to-first estrus and calving-to-conception intervals as well as lower conception rates than average producing cows without cysts. Cows with metritis were found to have significantly shorter calving-to-conception intervals but no detectable difference in conception rate or calving-to-first estrus interval than their herdmates. As lactation number increased reproductive performance improved. Cows that were observed in estrus earlier conceived earlier. Animals receiving uterine infusions had significantly longer calving-to-conception intervals and lower conception rates than their herdmates. There was no detectable difference in reproductive performance for cows treated with GnRH or PG compared with the nontreated cows. An increased estrus detection rate was associated with shorter calving-to-conception intervals and lower conception rates. Based on the range of performance in the study herds, the factors with the greatest potential influence on calving-to-conception interval in the average herd were the estrus detection rate and conception rate.

Yellow-flowered lucerne: Properties and influence on performance and reproduction of ewes

Conception rates and prolificacy of Finnish Landrace ewes fed yellow-flowered lucerne (Medicago falcata L.) pasture and silage prior to and during the mating period were compared with those of control ewes fed timothy (Phleum pratense L.) - meadow fescue (Festuca pratensis Huds.) pasture and silage. Ewes grazed pasture for four weeks and received their respective silage for 10 weeks indoors. Dry matter (DM) intake of lucerne silage was higher than that of grass silage (1.77 vs. 1.40 kg DM day-1). Timothy-fescue grass and silage analysed by a new modified method did not contain detectable amounts of plant oestrogens. In fresh and preserved lucerne, the amount of coumestrol was only moderate varying from zero to 59.5 ppm DM. Ewes fed lucerne received higher amounts of plant oestrogens than those on control feeding, but no differences in conception rate or lambing performance were found between the groups. However on lucerne, ewes conceived five days earlier (P=0.03) than control animals. Prolificacy of lucerne and control fed ewes averaged 3.13 and 3.19 lambs/ewe (P=0.76), respectively. There were no ewe health problems. The results suggest that the intake of yellow-flowered lucerne is good and the level of plant oestrogens has no detrimental effects on reproductive performance of adult Finnish Landrace ewes. ;

A model of litter size distribution in cattle.

Genetic increases in twinning of cattle could result in increased frequency of triplet or higher-order births. There are no estimates of the incidence of triplets in populations with genetic levels of twinning over 40% because these populations either have not existed or have not been documented. A model of the distribution of litter size in cattle is proposed. Empirical estimates of ovulation rate distribution in sheep were combined with biological hypotheses about the fate of embryos in cattle. Two phases of embryo loss were hypothesized. The first phase is considered to be preimplantation. Losses in this phase occur independently (i.e., the loss of one embryo does not affect the loss of the remaining embryos). The second phase occurs after implantation. The loss of one embryo in this stage results in the loss of all embryos. Fewer than 5% triplet births are predicted when 50% of births are twins and triplets. Above 60% multiple births, increased triplets accounted for most of the increase in litter size. Predictions were compared with data from 5,142 calvings by 14 groups of heifers and cows with average litter sizes ranging from 1.14 to 1.36 calves. The predicted number of triplets was not significantly different (chi2 = 16.85, df = 14) from the observed number. The model also predicted differences in conception rates. A cow ovulating two ova was predicted to have the highest conception rate in a single breeding cycle. As mean ovulation rate increased, predicted conception to one breeding cycle increased. Conception to two or three breeding cycles decreased as mean ovulation increased because late-pregnancy failures increased. An alternative model of the fate of ova in cattle based on embryo and uterine competency predicts very similar proportions of singles, twins, and triplets but different conception rates. The proposed model of litter size distribution in cattle accurately predicts the proportion of triplets found in cattle with genetically high twinning rates. This model can be used in projecting efficiency changes resulting from genetically increasing the twinning rate in cattle.

Effect of post-coital intrauterine inoculation of porcine reproductive and respiratory syndrome virus on conception in gilts.

The effect of porcine reproductive and respiratory syndrome virus (PRRSV) on early gestation was investigated by exposing susceptible gilts to the virus shortly after they had been bred naturally. Sixteen gilts were exposed intrauterinely to PRRSV and 23 gilts received a sham inoculum. One day after exposure, and on or about seven, 14, and 30 days after exposure, the gilts were bled and the serum was tested for PRRSV and homologous antibody. The pregnancy status of each gilt was determined on day 30 by ultrasound, and near or at term either by necropsy or by allowing the gilts to farrow naturally. All 16 gilts exposed to PRRSV became infected, as evidenced by the detection of PRRSV in seven of the gilts and homologous antibody in the serum of all of them, whereas all the 23 gilts exposed to a sham inoculum remained free of both virus and antibody. Ten of the 16 infected gilts conceived, and 19 of the 23 uninfected gilts conceived, but the difference in conception rate was not statistically significant. Moreover, the mean numbers of live fetuses or pigs per litter of the infected and uninfected gilts were similar (9.7 and 9.3). These results suggest that the intrauterine infection of susceptible pigs with PRRSV at or near the time of conception may have little or no effect on their reproductive performance.

Phosphorus Supplementation of Replacement Heifers in the Northern Great Plains

Studies were initiated in 1980 and 1984 to compare animal performance, dietary P levels, and serum mineral levels of P supplemented and unsupplemented replacement beef heifers (Bos taurus). Phosphorus supplementation levels averaged 4 g day-1 from 14 November 1980 and 24 January 1984, respectively, until 1 September 1980 and 15 October 1984, respectively, when supplemental P was raised to 6 g day-1. Heifers in both studies received mixed hay, primarily smooth bromegrass (Bromus inermis Leyss.), and rolled oats during their first winter and hay only the second winter. During the summer they grazed on native pastures which contained primarily western wheatgrass (Pascopyrum smithii (Rydb.) A. Love), needleandthread (Stipa comata Trin. and Rupr.), green needlegrass (S. viridula Trin.), blue grama (Bouteloua gracilis (H.B.K.) Griffiths), and upland sedges (Carex spp.). Hereford and Hereford-Angus cross heifers in the first study showed no weight gain or serum P response to supplemental P, but conception rate over the 2 studies was lower (P<0.05) for the unsupplemented heifers and 75% of the open heifers occurred in the first study. Hereford-Simmental heifers used in the second study demonstrated an immediate weight gain response (P<0.06) to supplemental P which persisted to the end of the study in 1985, but there was only 1 open heifer in the unsupplemented group in this study, compared to 3 in the first study. Serum P was higher (P<0.06) for P supplemented than control heifers only when they were removed from summer pasture in the second study. Diet P (2.10 g kg-1) for unsupplemented Hereford-Simmental heifers during the winter of 1984 was marginal, but diet P (2.53 g kg-1) for unsupplemented Hereford and Hereford-Angus heifers during the winter of 1980-1981 was clearly above recommended levels. Modest weight gain differences in the second study, serum P data and differences in conception rate suggest that Northern Great Plains forages are marginal to deficient in P for replacement beef heifers, but P supplementation would be expected to produce small and variable benefits.

Effect of Dietary Calcium Soaps on Milk Yield, Body Weight, Reproductive Hormones, and Fertility in First Parity and Older Cows

The effects were determined of dietary Ca soaps of fatty acids fed to cows to 120 DIM on milk yield, BW, peripheral concentrations of reproductive hormones, and fertility in primiparous and multiparous cows. Milk yield was increased in primiparous and multiparous cows fed Ca soaps, and milk fat and protein yields were enhanced. Body weight losses were greater for all cows fed Ca soaps, and this trend was greater and longer lasting in primiparous cows than in multiparous cows. Plasma triglyceride concentrations were elevated in multiparous cows, but FFA tended to be higher in primiparous cows fed Ca soaps. Conception rate at first AI was lower for primiparous cows fed Ca soaps (33%) than for controls (74%), but differences were not significant for later AI or between multiparous groups. No differences were apparent for plasma progesterone or estradiol in the luteal or follicular phases preceding the first AI, and differences in mean luteinizing hormone concentrations were small in a 6-h window in the follicular phase. The differences in conception rate at first AI in primiparous cows could not be explained on the basis of changes in peripheral hormone concentrations. The enhanced negative energy balance in primiparous cows fed Ca soaps apparently was related to the decrease in their conception rate.

Effect of immunisation of ewes against α 1–26 inhibin fragment on antibody titres, ovulation and lambing rate

Inhibin is involved in the regulation of follicle stimulating hormone (FSH) secretion and thus has a role in controlling the rate of ovulation. Immunisation of ewes against specific fragments of inhibin increases the ovulation rate. The aims of this study were to determine the persistency of antibody titres and changes in ovulation and lambing rates following immunisation against α 1–26 inhibin fragment conjugated to human serum albumin and given in non-ulcerative Freund's adjuvant. In Experiment 1, 38 multiparous ewes were randomised and either immunised (primary on Day 0 with a booster 1 month later) against 0.33 mg inhibin conjugate or left untreated. Weekly blood samples were collected to determine antibody titres at a dilution of 1:2000. The ovaries were examined by laparoscopy on eight occasions between Days 50 and 192. Antibody titres rose significantly in the immunised ewes after booster injection and remained high throughout the experiment. Seven (37%) immunised ewes demonstrated over 20% maximum binding of radiolabelled inhibin, and a further four (21%) ewes had more than 10% binding. There was a significant ( P<0.05) increase in ovulation rate in immunised ewes on each occasion. Six (32%) ewes had superovulatory responses (five or more ovulations) on repeated occasions following immunisation. A log-linear model showed a significant positive association between ovulation rate and antibody titre. The superovulatory response to exogenous equine chorionic gonadotrophin (eCG) treatment was not different in control and immunised ewes. In Experiment 2, 58 adult ewes were used and 29 were immunised as in Experiment 1. All ewes were treated with 60 mg medroxy progesterone acetate pessaries for 14 days; control ewes received 650 IU eCG at pessary withdrawal while immunised ewes received no gonadotrophin; rams were joined 2 days after pessary withdrawal. There was no difference in conception rates (86% vs. 90%) between control and immunised ewes. However, litter size to first service (2.35±0.16 vs. 1.76±0.16, P=0.016) and second service (2.66±0.33 vs. 1.50±0.28, P=0.046) was increased in immunised ewes. The results of these experiments demonstrate that immunisation against α 1–26 inhibin fragment increased ovulation rates from September until February and increased litter size, without having any effect on conception rate in synchronised ewes.

Treatment of infertility associated with endometriosis by selective tubal catheterization under hysteroscopy and laparoscopy

Objective: To evaluate the efficacy of treatment for infertility associated with endometriosis by selective tubal catheterization under hysteroscopy and laparoscopy. Study Design: Eighty-eight infertile women who underwent selective tubal catheterization with insufflation of oil-soluble radiopaque dye were reviewed. The efficacy of treatment was analyzed with regard to conception rate. Results: The conception rate after selective tubal catheterization was higher in women with endometriosis (60%) than in women without endometriosis (36.5%) ( p < 0.05). Most women conceived within the first 4 months after treatment. No statistical difference in conception rate was observed among patients with stage I, II, or III disease. Conclusions: Selective tubal catheterization with insufflation of oil-soluble radiopaque dye was an effective treatment for infertility associated with endometriosis.