Plasma LH, Ovulation and Conception Rates in Cats Mated Once or Three Times on Different Days of Oestrus

Although cats are induced ovulators, the relationship between the day of breeding, the number of matings and the likelihood of ovulation and conception have not been extensively investigated. In this experiment, cats were mated either once or three times on day 1 or day 5 of oestrus to study the incidence of the LH surge, ovulation and conception rates. The percentage ovulating and the conception rates after a single mating on day 1 of oestrus were 60% (6/10) and 33.3% (2/6), respectively, and for cats mated once on day 5 of oestrus were 83.3% (10/12) and 40% (4/10), respectively. When cats were mated three times on day 1 of oestrus, the ovulation rates and conception rates were 70% (7/10) and 85.7% (6/7), respectively, and for those mated three times on day 5 of oestrus were 100% (10/10) and 100% (10/10), respectively. The concentration of LH did not increase in non-ovulating cats, and cats that were mated three times had LH concentrations that were numerically higher than those that were mated once. Litter size was neither related to the day of mating nor to the number of matings. Although an increase in the number of matings on day 1 of oestrus produced a numerically larger LH surge, it did not increase the ovulation rate, suggesting that plasma oestradiol concentrations were not sufficiently elevated to induce a high pituitary response to mating stimulation. The conception rate after a single mating was low, suggesting that the number of sperm per mating was not sufficient. These results suggest that mating more than once in the middle of oestrus is required to improve ovulation rates and conception rates in cats.     

重复交配对雌性金州黑色标准水貂繁殖性能的影响

为建立完善的金州黑色标准水貂交配体系,选择性成熟的雌性和雄性金州黑色标准水貂,采用同一雄性的2次交配("1+1"、"1+7"或"1+8")、同一雄性3次交配("1+7+1'或"1+8+1")、不同雄性2次交配("A1+B7"或"A1+B8")和不同雄性3次交配("A1+A7+B1'、"A1+B7+B1"或"A1+B7+...     

Reproductive Performance of Thoroughbred Mares in Sweden

During 1997–2001, a total of 430 Thoroughbred mares were mated by one of the two Thoroughbred stallions on a well‐managed stud farm in the central part of Sweden. On arrival, a thorough gynaecological examination of all mares was performed. An early pregnancy examination was performed on days 14 and 15 after ovulation. The overall conception rates for the two stallions were 92.2 and 88.8%, and the corresponding live foal rates were 82.6 and 75.2%, respectively. The mean number of served oestrous cycles was 1.60 per mare per conception and 1.86 per live foal. The first and second cycle conception rates are reported for different age groups, mare categories and month of mating. The age of the mares had a significant influence on the live foal rate, being lower for mares >13 years of age. Resorption and abortion occurred in higher percentages among mares >8 years of age. The highest embryonic death occurred among mares with a history of being barren, or with having resorbed or aborted foetuses during the previous season. The month of mating had no significant influence on the first cycle conception rate or the second cycle conception rate. The frequency of twinning was 10.5% and the results of manual crushing of one of the conceptuses was successful in 88.9% of all cases, according to the ultrasound scanning 2 days later.     

Reproductive efficiency of intensively managed Thoroughbred mares in Newmarket

The findings of a retrospective survey of 1393 Thoroughbred mares visiting 22 studfarms in the Newmarket region of the UK during the 1998 mating season were compared with those of a similar study undertaken in 1983. The effects of mare age and status, stallion, month of mating, application of uterine treatments and other parameters on the rates of singleton and twin conception and subsequent pregnancy losses were analysed. Mare age and status significantly affected the per cycle pregnancy rate and the incidence of pregnancy loss. Overall, the mean number of matings per oestrus was 1.12 and the mean number of times a mare was mated until diagnosed pregnant at 15 days after ovulation was 1.88. An overall mean per cycle pregnancy rate of 59.9% at 15 days after ovulation resulted in 94.8% of the mated mares being pregnant at least once at 15 days after ovulation. This high initial pregnancy rate fell to 89.7% by Day 35 and 87.5% by the time of the October pregnancy test; 82.7% of the mares surveyed gave birth to a live foal at term, which compares favourably with the proportion of mares foaling in 1983 (77%). However, despite improvements in the foaling rates over the last 15 years, the overall rate of pregnancy failure remains high and represents a major loss to the Thoroughbred breeding industry.     

Factors influencing litter size in swine: parity-one females

The influence of age at conception, number of matings per conception, season of conception, and breed of female on parity-1 litter size was investigated in 4,944 females from 5 commercial swine herds located in North America. The influence of age at conception on reproductive performance of females in subsequent parities also was investigated. As the age at conception increased from 180 to 245 days, litter size increased 0.017 and 0.012 pig per day, respectively, (P less than 0.05) in 2 of the 3 herds that recorded such data. Age at conception did not influence litter size when conception occurred after 245 days of age. Longevity (parity achieved before death or culling) of females was not influenced by age at first conception. Gilts that conceived before 220 days of age had significantly shorter weaning-to-conception intervals in one herd and shorter farrowing-to-conception intervals in another herd throughout subsequent parities. In 1 of 3 herds that recorded such data, live and total litter size increased from 9.46 to 10.46 and 10.16 to 11.50, respectively (P less than 0.05), as number of matings increased from 1 to 3 per conception. No significant influence of number of matings per conception was observed in the other 2 herds. The effect of season of conception was variable among herds. In 2 herds, there was no significant effect of season of conception on subsequent litter size.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of Mating Frequency on Sow Reproductive Performance under Field Conditions and Natural Mating in Large Outdoor Production Units

The effect of mating frequency on fertility and litter size of sows, kept in outdoor production systems was investigated. Sows that were mated once or twice during a single oestrus were included in the study to compare the effect of number of matings on farrowing rate and litter size. Natural mating was used during the study period. Four groups of sows of parity two or more were either mated once 28–30 h after the onset of oestrus or were mated 28–30 h after the onset of oestrus and again 24 h later. The farrowing rate did not differ significantly between single‐ and double‐mated sows, although a noticeable but non‐significant depression in farrowing rate was evident between the groups of single‐mated and double‐mated animals. With the exception of total‐born litter size (p > 0.05), the total number born and number of live‐born piglets per litter were significantly (p < 0.05) lower in the group of sows that received only one mating compared with the double‐mated animals. The implication of these results is that the double mating by natural service of sows kept in an outdoor production systems may improve litter size.     

Pregnancy detection in putatively unmated mink (Mustela vison) by serum progesterone level

The aim of this study was to determine whether blood plasma progesterone is a reliable indicator of pregnancy in mink at an early stage of gestation. We also attempted to establish the threshold value of progesterone as a pregnancy indicator. The analysis was carried out at a production farm on 42 standard female mink aged 1 year, which were grouped both according to the observed success of mating ("mated" and "unmated") and the level of blood serum progesterone measured afterwards ("pregnant" and "nonpregnant"). It was next verified whether a particular female had been assigned to the proper group in the first place. An analysis of accuracy of mating success assessment within the group of unmated females revealed that more than one-third of decisions were wrong, since some females that had been considered unmated ultimately whelped. This suggests that mating supervision by farm workers lacks reliability. A progesterone test for verification of such management decisions should limit the risk of err,or. We suggest that progesterone tests could be carried out using the threshold values 1.9 ng/ml and 20 ng/ml in blood sampled on 25 March and 8 April, respectively, although some level of uncertainty should be taken into account.     

Longevity, lifetime pig production and productivity, and age at first conception in a cohort of gilts observed over six years on commercial farms.

An observational cohort study was conducted using a producer group of 33 farms selected based on their completeness of reproduction data, including dates of birth, entry to a herd, and removal. Average lifetime pig production and parity at removal in a cohort of 2,265 females born in 1990 were 67.2 pigs born alive and 5.6 parities, respectively. Approximately 90% of farrowings occurred from the second through the fourth year from birth. Farrowing rates between parities of 2 and 4 were higher than other parities, and pigs born alive from parities 3 to 5 were the greatest among parities. The 10th and 90th percentiles of age at first conception were 227 and 322 days. Increasing the age at first mating was associated with low farrowing rate (P<0.01) in parity 0. Older age at first conception was associated with lower parity at removal, shorter reproductive herd life, and fewer lifetime pigs born alive (P< 0.01). Of the 2,265 breeding females, 253 (11.2%) were re-mated at parity 0 and farrowed. These sows with a record re-mating at parity 0 had lower parity at removal, less lifetime pig production and lower lifetime productivity than those with no re-mating at parity 0 (P<0.01). It is recommended that unbred gilts 230 days of age or older should be mated soon.     

The influence of mare numbers, ejaculation frequency and month on the fertility of Thoroughbred stallions

Reason for performing the study: Although considerable variation in per cycle pregnancy rates exists between Thoroughbred (TB) stallions, there is little information on factors that may influence this figure. Objective: To assess the influence of month, mare numbers and mating frequency on the fertility of TB stallions standing on studfarms in East Anglia, England. Methods: The daily breeding records of 31 TB stallions mating 3034 mares on 4851 occasions during the 2010 season were surveyed and related to first scan pregnancy rates. The influences of mare book size, month, number of matings per day and mating frequency or abstinence on per mating pregnancy rates were analysed. Results: The overall per mating pregnancy rate for all the stallions was 59.6%, but for individual stallions the figures ranged from 19.0% to 80.1%. The first mating occurred on 9 February and the last on 24 July and the per mating pregnancy rate per month was significantly reduced in June and July. The number of mares mated by individual stallions ranged from 15 to 161, giving a mean overall workload of 160 matings per 100 mares. The per mating pregnancy rate was not related to book size, the number of matings in the season or the mating frequency per day. However, some stallions showed differences in per mating pregnancy rate related to month or the number of ejaculations in the preceding 3 days. Conclusions: The majority of TB stallions are able to maintain good fertility despite large books of mares. However, 5 of the 31 stallions surveyed showed a per mating pregnancy rate of ≤50%. Potential relevance: This survey has identified wide differences between the per mating pregnancy rate in TB stallions. Identification of the factors involved through more comprehensive surveys would provide useful information for mare and stallion owners.     

Reproductive consequences of deficiency of uridine monophosphate synthase in Holstein cattle

Cattle heterozygous for deficiency of uridine monophosphate synthase required more breeding services per calving when mated to other heterozygotes than did matings of normal cattle. Gestation length, number of breeding services per calving, and days from breeding to pregnancy examination were monitored on 759 complete gestations, 76 false-positive pregnancy diagnoses, 14 false-negative pregnancy diagnoses, and 413 negative pregnancy diagnoses in a dairy herd between 1983 and 1987. For complete gestations, 15 heterozygote x heterozygote matings required 3.13 +/- 0.37 breeding services per calving, which was significantly more than the 2.05 +/- 0.05 breeding services required for normal x normal matings; gestation length and days from breeding to pregnancy examination were similar between mating types. For false-positive pregnancy diagnoses, females diagnosed pregnant, but subsequently found not to be pregnant, 5 heterozygote x heterozygote matings averaged 51 +/- 23 days of gestation, which was less than the 93 +/- 6 days required for 71 normal matings; services and days from breeding to pregnancy examination were similar between mating types. All false-negative pregnancy diagnoses, females diagnosed not pregnant but later found to be pregnant, were made on cattle with normal matings. For negative pregnancy diagnoses, heterozygous matings averaged 0.3 more breeding services per examination than normal matings.     

Reproductive performance of beef cow herds in New Zealand

AIM: To describe the reproductive performance of beef cow herds in New Zealand and to develop reference ranges for assessing the reproductive performance of individual herds from in-calf rates, that take into account variation in the length of mating periods. METHODS: Veterinary practices throughout New Zealand involved in beef cattle work were asked to collect reproductive data from seasonally calving beef cow herds mated in the spring of 2001 through to the end of summer of 2002. An estimate of conception rate (termed calculated conception rate: CCR) was determined for each herd, assuming that the conception rate was constant for each 21-day interval of the mating period. The algebraic relationship between CCR and in-calf rate at pregnancy testing was defined for mating periods of different durations and, therefore, given the in-calf rate and the duration of the mating period, a CCR could be determined for each herd. Expected pregnancy rates were recalculated from CCR data for a range of mating period durations to produce a look-up table for assessing herd reproductive performance. Reproductive data describing regional differences in in-calf rates and CCRs, bull:cow ratios, breed characteristics, start dates of mating and durations of mating periods were summarised. The effect of study variables in explaining CCRs was examined using a general linear model (GLM). RESULTS: Data were collected from 1,005 beef cow herds distributed throughout New Zealand. The median in-calf rate for all herds was 91%, the lower quartile was < or =88% and the upper quartile > or =94%. The mean CCR for herds with complete reproductive data (862) was 55% (SD 11), the lower quartile was < or =48% and upper quartile > or =61%. Median in-calf rates for 2-year-old heifers (mated at approximately 15 months of age), 3-year-old heifers (mated at approximately 27 months of age), and mixed-age cows were 90%, 91% and 92%, respectively. The study variables that accounted for significant variation in breeding group CCR in a multivariate GLM were 'region' (p<0.01) and 'date mating commenced' (<0.01). The adjusted R2 for the model was 0.055. CONCLUSIONS: The reproductive reference range produced provides veterinarians and herd managers with a quantitative method for assessing reproductive performance of beef cow herds compared with industry averages, from in-calf rates at the time of pregnancy testing and durations of mating periods.     

中国荷斯坦牛初配年龄对繁殖性能的影响

利用扬州大学农牧场979头第1胎中国荷斯坦牛初配年龄及其繁殖性能数据,分析不同初配年龄对受胎情期数、产犊到受胎时间间隔、产犊间隔、妊娠期等指标的影响。结果表明:初配年龄显著影响受胎情期数和妊娠期长短(P0.05),18月龄配种母牛受胎情期数和妊娠期均最低,初配年龄对产犊到受胎时间间隔和产犊间隔均无显著影响(P0.05),但随着初配月龄的不断增加,奶牛产犊到受胎时间间隔和产犊间隔有逐渐降低的趋势。     

Fertility of sows mated on different days of the week

The farrowing rates resulting from matings on different days of the week were determined for a 2800-sow intensive piggery in both 1983 and 1984. The results showed that sows mated early in the week achieved a significantly higher farrowing rate than sows mated late in the week (P less than 0.0001). During the seasonal (summer to autumn) infertility period, Wednesday matings resulted in a poor farrowing rate whereas for the rest of the year farrowing rates following Wednesday matings were similar to those for Sunday Monday and Tuesday matings. Consistent results were obtained for data from both years. It is proposed that the stress of regrouping unmated sows on Wednesday to accommodate newly weaned sows is responsible for this decrease in fertility. This study illustrates how detailed analysis of farrowing rates on a day of mating basis can identify a problem which is otherwise masked by weekly data.     

Reproductive performance of farmed red deer (Cervus elaphus) in New Zealand: III. Risk factors for yearling hind conception.

A 2-year longitudinal observational study of 15 red-deer farms was carried out in New Zealand from March 1992. Seven hundred yearling hinds were individually monitored for reproductive success. After mating, hinds were pregnancy tested by ultrasound and were classified as having conceived before 1 May, after 1 May, or as being not pregnant. Risk factors potentially affecting the probability of conception before 1 May or of conception that year were investigated using path analysis. To increase the probability of conceiving early, this study suggests yearling hinds should be selected prior to mating for high bodyweight and height. Young stags and hinds should be joined late summer (14 months of age) before mating. Mobs of yearling hinds should not be combined with large mobs of adult hinds. Paddocks with limited gullies, hills and trees should be chosen for mating. Finally, paddocks for mating should be away from human disturbance. To increase the probability of yearling hinds conceiving that year, yearling hinds should be in moderate-to-low body condition (around 2.5), and nutrition during mating should be prioritised to ensure optimal growth rates. Short and/or lightweight hinds may be mated successfully if they are well fed but they generally conceive later. Trees should be limited in the mating paddocks.     

Seasonal Variation of Reproductive Performance,Foetal Development and Progesterone Concentrations of Sheep in the Subtropics

The aim of the present study was to investigate the effect of breeding season [late spring (LSP) vs winter (WIN)] on reproductive performances, foetal development and progesterone (P₄) concentrations of sheep in the subtropics. Ewes of Farafra breed were exposed for mating in LSP (n = 79) and WIN (n = 45). Ultrasonographic examinations were performed at days 25, 45 and 75 of mating to estimate the pregnancy rate, incidence of twinning and percentage of foetal losses. Foetal growth rate was determined at 10‐day interval, and blood samples were taken on days 0 (oestrus), 8, 18 of oestrous cycle and on days 30, 45, 60 and 90 of pregnancy for P₄ analysis. The results showed that pregnancy and lambing rates were greater (p < 0.01) for ewes mated in LSP (93.7% and 92.4%) than for those mated in WIN (75.6% and 71.1%), respectively. There was no effect of season on the incidence of twinning (overall 19.1%) or the frequency of foetal losses (overall 7.3%). Transient reduction of placental size, foetal growth and P₄ concentration was observed following LSP matings. In conclusion, pregnancy and lambing rates were higher following LSP matings. Summer heat stress of the late spring mated ewes transiently interferes with foetal growth and P₄ concentrations.     

Plasma progesterone concentrations in pregnant and non-pregnant llamas (Lama glama)

Female llamas ovulate in response to copulation, and progesterone secretion by the corpus luteum indicates recent ovulation (mating) and, or, pregnancy. The plasma progesterone concentration was 0.9 to 1.4 ng/ml in five non-pregnant llamas and 7.4 to 9.2 ng/ml in three llamas in the last month of pregnancy. After ovulation had been induced in nine of 10 llamas by a single intramuscular injection of 500 or 750 iu of human chorionic gonadotrophin, the plasma progesterone concentration increased after two days from 0.5 to 1.2 ng/ml to 4.6 to 10.3 ng/ml after six to nine days and returned to basal values after 10 to 13 days, reflecting the life-span of a corpus luteum in the absence of conception. After a male llama had been introduced into a group of 13 females, 10 matings which resulted in eight conceptions occurred in the first 11 days, and 11 of the llamas became pregnant. The llamas' progesterone concentrations increased after mating and remained high if conception had occurred: 6 to 12 ng/ml in months one to four, and 5 to 9 ng/ml in months five to nine of the 11-month gestation. Two of the 13 llamas had high concentrations of progesterone although they did not become pregnant.     

Failure of a single postpartum prostaglandin treatment to improve the reproductive performance of dairy cows

A study was conducted to evaluate the effects of postpartum prostaglandin treatment on reproduction in 3 seasonal calving dairy herds. Recently calved lactating dairy cows were paired on herd, age, calving date and previous production index. One cow in each of the 196 pairs received a single intramuscular injection of 25 mg of the prostaglandin analogue, dinoprost, between 14 and 28 days after calving. Subsequent reproduction was monitored. Within each herd and overall, there was no significant effect of treatment on the intervals from calving to first service, mating start date to first service, calving to conception, mating start date to conception and first service to conception. Treatment also had no significant effect on 21-day submission and pregnancy rates, on the proportion of each group not pregnant at the end of mating, and on first service pregnancy rates. Responses to treatment did not vary between cows calving within 50 days of mating start date and earlier calving cows or between cows aged less than 5 years and older cows.     

组合添加剂对水貂繁殖性能的影响

为研究组合添加剂对水貂精子活力、配种率、平均窝产仔数、断奶成活率、断奶平均体重等繁殖性能的影响。选择种母貂36只、公貂6只,随机分为对照组和试验组,每组3只公貂,18只母貂,母貂设2个重复。对照组貂饲喂基础日粮,试验组在基础日粮基础中添加组合添加剂3 g/(d·只)。试验期120 d,试验期内,测定精子活力、配种率、平均窝产仔数、断奶成活率、断奶平均体重。结果显示,组合添加剂对貂的繁殖性能具有明显的改善作用。与对照组相比,试验组公貂精子活力、母貂受胎率、平均窝产仔数、仔貂断奶成活率和45日龄断奶平均体重等繁殖性能指标分别提高了2.44%、3.93%、13.04%、2.49%、1.85%。     

Reproductive characteristics of the feral raccoon (Procyon lotor) in Hokkaido,Japan

Reproduction of feral raccoons (Procyon lotor) in Hokkaido, Japan, was examined during a 2-year period by analysis of placental scars or fetuses in the uterus. Of 242 collected females, 69 (29%) were juveniles, 71 (29%) yearlings, and 102 (42%) adults. The pregnancy rate averaged 66% in yearlings and was significantly lower than the 96% average observed in adults (p<0.01). Litter size ranged from 1 to 7 offspring per female, and averaged 3.6 in yearlings and 3.9 in adults. There was no significant difference in mean litter size between yearlings and adults. In Hokkaido, the raccoon mating season peaked in February and the majority of litters were born between March and May, similar to patterns described in North America, but some females mated in summer. The reproductive potential of feral raccoons in Hokkaido was similar to that reported in North America. The recent increase in raccoon numbers can be explained by their high productivity. Harvest data suggest that hunting pressure on juveniles is lower than that for older age classes when using box traps in summer. In order to reduce the feral raccoon population, alternative hunting methods that increase juvenile mortality rates are needed.     

Effects of mating behaviour and the ovarian follicular state of female alpacas on conception

OBJECTIVE: To determine relationships between mating behaviour, ovarian follicular state and successful conception in receptive female alpacas. PROCEDURE: Seventy pen matings were observed at a commercial alpaca stud in south-western Victoria. The behaviours observed included time taken to assume sternal recumbency, mating duration, and evidence of nonreceptive behaviour such as spitting, kicking and vocalisation. Ovarian follicular state was determined by ultrasonography, which was complemented by measuring plasma concentrations of oestradiol and progesterone. Pregnancies were confirmed by transabdominal ultrasonography between days 45 and 80 after mating. RESULTS: There were no significant differences between receptive females that conceived and those that failed to conceive in the time taken to adopt the copulation position of sternal recumbency, mating duration, or maximum follicle diameter. There was no significant relationship between time taken to assume sternal recumbency (log10) and maximum follicle diameter or plasma oestradiol (log10). However, there was a significant quadratic relationship between plasma oestradiol concentration (log10) and follicle diameter, and the probability of pregnancy increased as the plasma concentration of oestradiol (log10) at the time of mating increased. Females were sexually receptive most of the time in the absence of a corpus luteum, and regardless of size of the largest follicle or plasma concentration of oestradiol. Breed (Huacaya vs Suri), site of the dominant follicle (left or right ovary), lactation state, number of matings by the male (1 or 2), or interval between parturition and mating, did not affect pregnancy outcome. Follicles with a diameter less than 7 mm were able to ovulate in response to mating. This was smaller than previously reported. Thirty-four pregnancies (49% pregnancy rate) resulted in 30 (88%) births with a gestation length of 343 days (SEM +/- 2, range 316-367 days). There were 4 (12%) abortions between days 45 and 80 of gestation and full term. CONCLUSION: It was not possible to correlate mating behaviour and ovarian state with conception. To optimise pregnancy rates in receptive alpacas, matings need to occur in the presence of an oestrogenic follicle that is capable of ovulation in response to mating. A simple method of detecting alpacas with follicles in this state is not currently available and treatments that control ovarian follicular growth should therefore be investigated.