Higher Conception Rate Research Articles

Conception Rates of Holstein Bulls for Artificial Insemination on a California Dairy

Data of milk production and reproduction were collected from a 2,500-cow dairy in California for measuring conception rates of bulls for artificial insemination. The bulls were placed into groups of low, medium, or high conception rates. Mean conception rates were 38.2%, 55.7%, and 66.1%, range 34% to 70%. To predict the conception-rate group of a bull required 30 services.There were no differences in average number of lactations and days to first service of the cows bred to the three groups of bulls. Cows bred to the bulls with high conception rate produced 667kg more milk than cows bred to bulls with low conception rate. Cows bred to the low bulls were bred, on the average, in mid-July, whereas cows bred to the other two groups were bred in June and May. The cost to this dairy for using low conception rate bulls was $21,000.

Estrus synchronization and controlled breeding in goats using prostaglandin F 2α

Estrus synchronization in the goat employing the double injection regimen of 7.5 mg of prostaglandin F 2α (Lutalyse) at each injection, resulted in 64% and 84% synchronization at first and second injections, respectively. Breeding at estrus induced by the second injection resulted in 90% conception. Kidding at the end of the gestation period was spread over a 17-day period. The first and the last does had 141 and 158 days of gestation, respectively. The findings of this study indicate that two injections of prostaglandin F 2α 10 days apart is superior to a single injection for estrus synchronization in the goat. Breeding following the second injection resulted in high conception rate. Due to individual differences in gestational lengths, estrus synchronization with prostaglandin F 2α cannot be depended upon for synchrony of kidding.

Characteristics of the menstrual cycle in nonhuman primates. III. Timed mating in Macaca arctoides.

Analysis of five years of reproductive data from Macaca arctoides showed the mean menstrual cycle length was 29.9 +/- 4.4 days. Using timed mating, a conception rate of 16.3% was observed. The highest conception rate occurred after matings on day 11 of the cycle. Eight pregnancies went to term and the mean gestation length was 172.4 days. The sex ratio was 137.8 males per 100 females in fetuses obtained on day 100 post-conception.

Control of estrus in bos indicus and bos taurus heifers with prostaglandin F 2 alpha

Lutalyse * , a commercial preparation of prostaglandin F 2a was injected intramuscularly into nulliparous heifers of the German Brown, Holstein—Friesian and White Fulani cattle. Two injections, 25mg/animal each time, were given at intervals of 12 days. All the heifers were inseminated 80h after the second injection. Heifers that were cycling responded well to the treatment and had a higher conception rate than the controls.

REPRODUCTIVE EFFICIENCY OF ARTIFICIALLY BRED HOLSTEINS IN QUEBEC

A total of 2216 lactations, initiated between July 1973 and June 1976, of 1382 Holstein cows in 36 herds from the Nicolet, Rock Forest and St-Hyacinthe regions of Quebec were studied. All cows were bred exclusively by AI. Mean services per conception, percent conception on first service, days from calving to first service and days open were 1.97 services, 47%, 88 days and 121 days, respectively. Based on maximum likelihood estimates of cow and error variance components, repeatabilities of services per conception, days from calving to first service and days open were 0.04, 0.09 and 0.07, respectively. Cows calving in spring had better reproductive performance than those calving during other times of the year. Reproductive efficiency was lower among both 2-yr-old and mature cows compared to intermediate aged cows. Lower reproductive efficiency was also associated with cows at high milk production levels. As herd size increased, conception rates declined. Herds feeding at high levels of net energy had higher conception rates than herds with low and medium net energy intake levels. Dairymen who managed their labor efficiently for milk production had herds with high reproductive efficiency.

Use of the prostaglandin F 2α analog cloprostenol (ICI 80, 996) in dairy cattle with unobserved estrus

Two field trials were designed to evaluate use of the prostaglandin F 2α analog cloprostenol (CP) in dairy cattle with unobserved estrus and a palpably mature corpus luteum (CL). In Trial 1, 98 cows were treated with CP (500 μg IM) and 83 were given saline. Cows in both groups were assigned to be inseminated based on observed signs of estrus. Cows treated with CP were inseminated sooner than controls although heat detection still presented some difficulty. Conception rates were the same for both groups. In Trial 2, 154 cows were treated with CP for unobserved estrus and were assigned to be inseminated at estrus (78 cows) or were inseminated twice by appointment at 72 and 96 hours after treatment (76 cows). Appointment breeding eliminated problems associated with detection of estrus so nearly all cows were inseminated soon after treatment. In addition, cows bred twice by appointment had a higher conception rate than those bred based on signs of estrus. Induction of luteolysis with the prostaglandin F 2α analog CP in cows with unobserved estrus and a CL should prove to be a very effective addition to reproductive herd health programs. Successful use of CP for this purpose is dependent upon accurate diagnosis of the presence of a mature CL. In these trials 83 (92.4%) of 90 cows sampled had blood serum progesterone concentrations indicative (≥ 2.0 ng/ml) of significant luteal tissue activity.

Net Returns from Using Genetically Superior Sires

The net present value of a unit of semen from a genetically superior sire is compared with the net present value of a unit from a sire with predicted difference milk of zero. The method includes all ensuing female progeny and lactations in as many future generations as desired. Variables include conception rate for the initial unit of semen, probabilities of survival of cows to various ages, predicted difference milk and fat for the sire, price of milk, mature equivalent production factors to convert to actual yield, probability of female calves, age at first calving, calving interval, costs of extra feed and health care for daughters of superior sires, minimum attractive annual rate of return, years to recover investment, and the base price of a unit of semen from an average bull with predicted difference of zero.For a fixed set of parameters, the net present value varies linearly with the predicted difference for dollar value (PD$) of the bull. In a typical example with milk selling for $22.05/100kg, the net present value for semen from a bull with PD of +454kg compared with an average bull is .39 PD$, .25 PD$, .05 PD$ for years of investment recovery 20, 10, and 4, the latter representing one lactation from the initial daughter. Returns are from milk only. Semen from genetically average bulls with high rates of conception is as valuable as semen from high PD bulls with average conception. Conception rate influences whole lactations in addition to genetic superiority.

A SURVEY OF DAIRY HERDS IN THE FRASER VALLEY OF BRITISH COLUMBIA TO DETERMINE POSSIBLE CAUSES OF UNSATISFACTORY REPRODUCTIVE PERFORMANCE

In a preliminary study of reproductive performance of 261 dairy herds in the Lower Fraser Valley of British Columbia for the period 1966 through 1970, mean non-return rate was 4.7% less in 1970 than in the previous 4 yr. In February 1972, factors associated with the reproductive performance of 68 herds in the same region were studied in greater detail. Herd non-return rates for 1971 were estimated from artificial insemination (AI) unit records. Feed samples, soil samples, feed intakes, and herd production levels were obtained for each period. The results indicated that differences in mineral nutrition between herds were associated with reproductive performance. The Cu/Mo ratio in silage was the most important factor, with increases in Cu relative to Mo being associated with low herd non-return rates. Other minerals found to be important included the Cu/Mo ratio in hay and grain, Cu in hay, Mo and Se in grain, Ca and P in silage and the variability of soil Mg levels. The type of forage fed was also important, with herds receiving diverse rations having higher conception rates than those restricted to one type of silage and/or hay.

EPIDEMIOLOGY OF TWIN BIRTHS FROM A CLIMATIC POINT OF VIEW

The twinning rate was analysed using figures taken from statistics for Japan. During the years 1955 to 1959 there were 58 570 twin deliveries out of a total of 9 088 233, a frequency of 6-44 per 1000. Using Winberg's differential method for zygosity estimation, the monozygotic twinning rate was 4-04 per 1000 and the dizygotic was 2-40. Twinning rates in 46 prefectures were also estimated and their correlations with meteorological parameters as well as with the mortality from cerebrovascular disease were examined. The twinning rates increased from a low level in the south west to a high level in the north east of Japan. The tendency was more obvious for the dizygotic than the monozygotic twinning rate. A negative correlation was observed between incidence rates of dizygotic twins and mean air-temperatures throughout the year, and a positive one between incidences of dizygotic twins and mortality rates for vascular lesions affecting the central nervous system in 46 prefectures. A seasonal variation of twinning rates was also observed in Niigata City for statistics of births during the periods 1948-55 and 1963-70. This took the form of a bimodal curve, with high conception rates for twin births in intermediate mild seasons, the spring and autumn and, low rates in the more stressful hot and cold seasons. These relationships between climate and twin births within a single race-group are discussed.

VII. Interactions involving semen fertility levels, sperm dose rate, and technician ability

Abstract From among 122 inseminating technicians employed by the Taranaki Livestock Improvement Association, the results obtained by the group of 7 technicians achieving the highest conception rates in cows (C.R. = 1- to 49-day non-return rate) when using semen of above-or below-average fertility were compared with the results obtained by the group of 7 technicians achieving the lowest conception rates in cows. The C.R. difference between the two groups of technicians when using semen of above-average fertility was 11.8% compared with 11.6% when using semen of below-average fertility. A similar trial, with 8 technicians in each group, showed that increasing the dose rate from 2.5 × 106 total sperm did not significantly reduce the C.R. differences between the 2 groups (6.5% v. 6.3%). sperm per insemination with 16 ejaculates of semen when processed in Caprogen containing Split-batch procedures were used to compare dose rates of 2.5, 3.75, and 5.0 × 106 total catalase (8 sires × 2 ejaculates per sire). The ...

Epidemiology of twin births from a climatic point of view.

The twinning rate was analysed using figures taken from statistics for Japan. During the years 1955 to 1959 there were 58 570 twin deliveries out of a total of 9 088 233, a frequency of 6-44 per 1000. Using Winberg's differential method for zygosity estimation, the monozygotic twinning rate was 4-04 per 1000 and the dizygotic was 2-40. Twinning rates in 46 prefectures were also estimated and their correlations with meteorological parameters as well as with the mortality from cerebrovascular disease were examined. The twinning rates increased from a low level in the south west to a high level in the north east of Japan. The tendency was more obvious for the dizygotic than the monozygotic twinning rate. A negative correlation was observed between incidence rates of dizygotic twins and mean air-temperatures throughout the year, and a positive one between incidences of dizygotic twins and mortality rates for vascular lesions affecting the central nervous system in 46 prefectures. A seasonal variation of twinning rates was also observed in Niigata City for statistics of births during the periods 1948-55 and 1963-70. This took the form of a bimodal curve, with high conception rates for twin births in intermediate mild seasons, the spring and autumn and, low rates in the more stressful hot and cold seasons. These relationships between climate and twin births within a single race-group are discussed.

Production of rats in synchronised batches.

Successful synchronisation of copulations and births for the 1st parity permit continued synchrony of parturitions in subsequent parities. Foetal implantation after post-partum copulation was delayed by multiples of the oestrous cycle; both season and number of sucking neonates influenced the time of implantation. Post-weaning matings gave a high conception rate with a parturition spread of 36 hours for 94% of the original group.

Semen cahracteristics before and after ligation of the left internal spermatic veins in men with varicocele.

The semen from 20 men with varicocele was studied before and after surgical correction of the varicocele. The effect on sperm quality was only marginal and could not explain the fairly high conception rate (20%) after operation. The recommendation that varicocele in men with long-term infertility should be eliminated by ligation of the internal spermatic veins is still justified despite the absence of positive effects on sperm quality.

Effect of short-term progesterone treatment on oestrous response and fertility in heifers.

Summary. The reasons for a reduced oestrous response in heifers following a 9-day treatment with implants of progesterone were determined. Progesterone implants were inserted into Hereford cross heifers for 9 days at different stages of the oestrous cycle. Oestradiol benzoate (5 mg) was also given at the time of insertion of implants. The oestrous response obtained was low in animals receiving implants on Days 3 or 17 but was high in those receiving implants between Days 5 to 15. Injecting 50 mg progesterone with the 5 mg oestrogen increased the oestrous response in animals receiving implants on Day 17 but the onset of oestrus was more variable following this treatment in animals receiving implants on Day 3 or between Days 5 and 15. Removing the implants after 12 days instead of 9 days, however, gave a precise onset of oestrus. The conception rate to A.I. was not different in heifers synchronized with a 9- or 12-day treatment from that of the controls but it was lower in heifers synchronized with implants of progesterone removed after 18 or 21 days. The high conception rates obtained at slaughter 30 to 40 days after the last insemination were substantiated by allowing a group of heifers to calve after synchronization with a 9-day progesterone treatment.

Survey observation on the mating performance of sheep in New Zealand Romney stud flocks

The mating performance of 2075 New Zealand Romney rams joined singly with 127,683 ewes for three 16-day periods during the breeding season is given. These observations were conducted between 1962 and 1969 in stud flocks situated in four geographical localities based on latitude, throughout New Zealand. Area differences were observed in mean dates of first joining, in the number of ewes in oestrus, and in conception and return rates. Rams were joined with the ewes later in southern areas. When compared with flocks in the North Island, southern flocks showed a higher proportion of ewes detected in oestrus during the first 16 days of mating, higher conception rates, and lower return rates. Wide differences were observed between rams as regards the conception rate of ewes. Significant correlations between numbers of ewes joined and proportions of ewes detected in oestrus showed a quadratic rather than a linear fit, with marked differences from north to south. There were no significant correlations between the number of ewes joined and percentage conception rate.

Economic analysis of Red Chittagong Cattle farming system in some selected areas of Chittagong district

The study was carried out in 5 Upazilas under Chittagong district with a view to analyze the present socio-economic status of RCC farming practices on 100 RCC rearers (Potiya, Raujan, Chandanaish, Anowara and Satkania Upazila). The study showed that, about 39.00 percent of RCC farm owners were landless, 31.00 percent were small and marginal farmers, 17.00 percent were medium and 13.00 percent were large farmers according to their landholding sizes. The cost of rearing RCC per cattle per year was found to be Tk. 17503.76, Tk. 15540.27, and Tk. 33044.03 as cash cost, non cash cost and total cost respectively. The study also revealed that, average daily milk yield, lactation yield and lactation length of RCC were found to be 2.71 liters, 581.61 liters and 215.41 days, respectively. The average per year per cattle gross return of RCC was found Tk. 25390.41. The gross returns over cash cost and full cost basis of rearing per lactation per cattle of RCC were found at Tk 8058.642 and Tk.-7501.53, respectively. The benefit cost ratio on the basis of cash cost and full costs per year per cattle was found 1.47 and 0.77, respectively. The study also revealed that, the rural farmers prefer RCC farming than other breeds due to high conception rate, each year calving, disease resistance, high milk fat per cent and cost effective farming. Keyword: RCC; Cost; Return; Profitability; Disease Occurrences DOI: 10.3329/jbau.v8i2.7937 J. Bangladesh Agril. Univ. 8(2): 271-276, 2010

Inheritance of Fertility in Cattle Inseminated Artificially

Higher conception rates were obtained in both virgin heifers and cows when the following estrus characteristics were present at insemination: good standing heat, presence of heat mucus, intense red color of the internal portion of the vagina, easy cervical passage with a pipette, good uterine contractions, normal ovaries and follicles, and soft follicles. Precise determination of these estrus characteristics was difficult, and heritability estimates ranged from 0 to 0.24. Consequently, an improvement in fertility by selection of these characteristics would be uncertain.Heritability and repeatability estimates of nonreturn rates after first insemination in virgin heifers in herds with low fertility were 0.17 and 0.23, respectively, and nearly zero in herds with good fertility. Thus, the use of nonreturns to first insemination for virgin heifers in herds with low fertility appears to be more valuable for fertility improvement through selection, because 1) these data can be obtained very easily and 2) this measurement determines the fertility complex better than other traits evaluated.

MPA impregnated intravaginal sponges for the induction of oestrus in anoestrous Border Leicester × Merino ewes. 1. Lactating ewes

In the spring of 1965, anoestrous lactating Border Leicester X Merino ewes were treated for 13 days with intravaginal sponges impregnated with 17a - acetoxy 6a - methylpregn - 4 - ene - 3,20 - dione (MAP) 7-11 weeks after lambing. Each ewe received 1000 i.u. Pregnant Mare Serum Gonadotrophin (PMSG) at the time of sponge removal. Half of the ewes received another 1000 i.u. PMSG 16 days after sponge removal. In the 2-4 days after sponge removal 80.5 per cent of the treated ewes exhibited oestrus, and 75.8 per cent of these were pregnant at autopsy 15 weeks later. The mean number of foetuses per pregnant ewe was 2.46. It was not until approximately 15 weeks after the period of treatment that a similar number of untreated ewes had exhibited oestrus. The second injection of PMSG had no effect on either the number of ewes pregnant or on the number of foetuses present at autopsy. This was largely due to the high rate of conception at the first induced oestrus.

The Effect of Visual Isolation on Reproduction in the Female Ranch Mink

Visual isolation of female ranch mink ( Mustela, vison ) caused alterations in their reproductive performance. Estrus was delayed and the isolation was considered inhibitory to sexual development prior to the normal breeding time. However, slightly lower pre- and post-natal mortality rates, a considerably higher conception rate, and increased litter sizes for the isolates indicated that visual isolation subsequent to fertilization may raise the reproductive potential by reducing the social stress on the animal.

Improvement of conception rate and diagnosis of pregnancy in sows by an androgen-oestrogen-depot preparation.

This paper records observations made on conception in sows treated with a long-acting androgen-oestrogen mixture. The observations were made as part of an experiment originally undertaken to examine the value of treatment with this agent for the diagnosis of pregnancy in pigs. It has previously been observed that administration of a similar mixture was followed by heat in cattle previously showing ovulation in the absence of heat. By the same treatment an ovulatory heat was induced in anoestrous, barren animals, but existing pregnancies were not disturbed (J\l=o\chle,1964). It seemed probable that the existence of pregnancy would be established if heat failed to occur following administration of the agent. Two milligrammes oestradiol valerate and 5 mg testosterone enanthate were administered to sows 9 to 12 days following service. The experimental group comprised ninety-eight German Landrace sows (from two research farms of the Max-Planck-Institute) served at the first heat following weaning. A group of 619 sows at the same farms, mated over the experimental period, served as controls. The matings of the treated animals were made by a total of sixteen boars (see Table 1). Only animals which farrowed were judged to have been pregnant. All non-pregnant sows showing heat were mated again immediately. Treatment with the androgen-oestrogen mixture proved highly effective as an indicator of the existence of pregnancy : all treated non-pregnant sows showed heat, but no treated pregnant sow showed heat symptoms. Unexpected was the unusually high conception rate of the treated animals: 90\m=.\8% (89 out of 98 sows) farrowed compared with 78\m=.\2%(484 out of 619) control animals (P = 0\m=.\01). This percentage varied from 15 to 25 % between the two farms and the boars used for mating. To eliminate those influences, treated and untreated animals mated by the same boar have been compared. Table 1 summarizes the farrowing performance of sows mated to the individual boar. It is shown that there were considerable differences in fertility between boars. Altogether conception rate among treated sows is higher (90\m=.\8%) than that among untreated sows (81\m=.\9%)(P = 0\m=.\05). In seven out of nine boars treatment apparently increased the number of sows mated successfully. There is no evidence