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At least 631 records · Page 35Linked to original sources
PubMed1995

Effect of treatment with ivermectin on reproductive performance of yearling beef heifers.

To determine the effect of treatment with ivermectin on reproductive parameters, 78 fall-born, yearling heifers were allotted to either an ivermectin treatment group or to the control, non-treatment group. The heifers were treated in June and October when they were approximately 7 and 11 mo old, respectively. Ivermectin effectively lowered fecal egg counts in the treated heifers compared with that of the controls. In heifers that were maintained on a marginal plane of nutrition, treatment with ivermectin not only improved weight gains during each recording period but also hastened the onset of puberty and improved the pregnancy rate during a 60-d breeding season. The positive effect of ivermectin on these reproductive characteristics could not be explained by increased weight gain alone, because the correlation between weight gain and puberty was not significant. Treatment with ivermectin positively affected pelvic area but not uterine score when compared with those of the controls.

Journal Article↗
PubMed2006

Reproductive performance of captive collared peccaries (Tayassu tajacu) in the eastern Amazon.

This study analyses reproductive parameters resulting from 74 parturitions in a population of captive collared peccaries in the eastern Amazon (Belém, State of Pará, Brazil) during a 65-month survey. Parturitions were homogeneously distributed throughout the year. The average litter size was 1.85 newborns per parturition. Collared peccary females had a newborn sex ratio of 52.6% females and 47.4% males. The mean age at first parturition was 639, although, the earliest first parturition occurred at age of 381 days. Estimated parturition-conception interval was 58 days. Mean farrowing interval was 196 days and mean production was 1.03 litters and 1.86 newborns per year per female. Mortality rate in newborns less than 2 months old was 26.9% of the total newborn population. Most identified causes of death were abandonment by the mother (22.2%) and trauma due to aggression (13.9%). Newborn deaths occurred mainly during the first two days of life. This study suggests that the collared peccary possesses interesting reproductive parameters for its introduction in captive breeding programmes in the Amazon region.

Animal Husbandry↗
PubMed1977

The effect on reproductive performance of porcine parvovirus infection in a susceptible pig herd.

An acute episode of reproductive failure occurred following natural introduction of porcine parvovirus to a susceptible herd of 48 breeding sows. Serological data gave a close estimate of the time that infection spread through the herd, and enabled a correct forecast of the reproductive failure that followed. Severe fetal mummification was seen over a three-week period. Epidemiological data is presented strongly linking in utero parvovirus infection with the mummification that occurred, and the significance of this data is discussed in connection with the present knowledge of transplacental porcine parvovirus infection.

Animals↗
PubMed1996

Reproductive Performance of Women with Uterine Anomalies after Abdominal or Hysteroscopic Metroplasty or no Surgical Treatment

The reproductive outcome of 404 women with confirmed uterine malformations was studied. The most common uterine anomaly was complete or incomplete septate uterus (48%). Bicornuate uterus was found in 17% of women, and unicornuate and didelphic both in 10%. The fetal survival rates without metroplasty were 70% for the partially bicornuate group, and 76% and 63% for the septate and subseptate groups, respectively. Metroplasty was performed in 64 (26%) of 247 women with a septate, subseptate, or partially bicornuate uterine abnormality. The indication for operation in most women was recurrent spontaneous abortions. Abdominal metroplasty (Strassmann or Jones procedure) was carried out in 12 (22%) of 55 women with a partially bicornuate uterus. Metroplasty was done in 52 (27%) of 192 women with a septate or subseptate uterus. Abdominal metroplasty (Jones or Tompkins procedure) was used in 20 patients, and transcervical metroplasty by means of hysteroscopic scissors or resectoscopic division in 32. In all, the reproductive outcome improved from 9% successful pregnancies before to 84% after metroplasty.

Journal Article↗
PubMed2005

Reproductive performance of anestrous dairy cows treated with progesterone and estradiol benzoate.

Anestrus is a major reproduction problem in pasture-based dairy operations that results in poorer reproductive outcomes than herdmates detected in estrus before the start of the seasonal breeding program. The objective of the current study was to assess a combined progesterone and estradiol benzoate treatment program including resynchrony with no treatment. Anestrous pasture-fed dairy cattle (n = 756) in 9 herds were blocked by herd and age and assigned within sequentially presented pairs of cows to be treated with an intravaginal progesterone-releasing insert for 8 d plus 2 mg of estradiol benzoate injected i.m. at insert insertion and 1 mg of estradiol benzoate injected 1 d after insert removal (d -1). Those cows detected in estrus from 0 to 3 d had a used progester-one-releasing insert reinserted for 6 d commencing on d 16 with 0.5 mg of estradiol benzoate injected i.m. 1 d after insert removal (treatment). The other cow within the pair was left as an untreated control (control). Treatment increased the risk of insemination and pregnancy by 28 d into the breeding program and resulted in conception 15 d earlier compared with controls. In contrast, treatment did not increase the risk of pregnancy after 56 d into the breeding program or at the end of the breeding season. It is concluded that treatment of anestrous dairy cattle with progesterone and estradiol benzoate combined with reinsertion of the progesterone insert resulted in earlier conception, but no difference in the final pregnancy rate compared with no treatment.

Analysis of Variance↗
PubMed2007

Associations between basal metabolic rate and reproductive performance in C57BL/6J mice.

Basal metabolic rate (BMR) is highly variable, both between and within species. One hypothesis is that this variation may be linked to the capacity for sustained rate of energy expenditure, leading to associations between high BMR and performance during energy-demanding periods of life history, such as reproduction. However, despite the attractive nature of this hypothesis, previous studies have failed to show an association between BMR and fecundity. Our approach was to mate 304 C57BL/6J mice and allow them to wean pups before measuring BMR by indirect calorimetry. We did not find an association between BMR and litter mass, size or pup mass at birth or weaning that could not be accounted for by the body mass of the dam. There was also no relationship between BMR (or BMR corrected for body mass) and birth or weaning success, losses during weaning, or sex ratio. However, a significant relationship was found between BMR and gestational weight loss indicative of foetal resorption. This suggests that during pregnancy the available energy may be limited and partitioned away from the growing foetus and towards maintenance of the mother. In this context, a high BMR may actually be disadvantageous, conflicting with the idea that high BMR may bring reproductive benefits.

Animals↗
PubMed1989

Reproductive performance of three fat-tailed breeds of sheep mated to native, Corriedale and Targhee rams.

Reproduction and lamb production of three fat-tailed, carpet-wool Iranian breeds of sheep; Karakul (130 ewes), Mehraban (103) and Baluchi (119) were studied. The ewes were mated either as purebreds or with Corriedale or Targhee rams. The overall least-squares means for ewes mated (showed oestrus) or ewes exposed, ewes lambed or ewes mated, lambs born of ewes lambing (prolificacy), lambs born alive of total lambs born, lambs weaned of live lambs born, lambs weaned (75 days of age) of ewes mated, kg lamb weaned per ewe mated and kg lamb weaned per 100 kg ewe mated were 98.3%, 93.5%, 103.1%, 94.9%, 97.8%, 90.0%, 18.2 kg and 38.4 kg respectively. The native breeds were not different for any of the traits studied except for prolificacy which was higher in Mehraban than in Karakul. Purebred matings did not differ from the crossbred matings for any of the traits concerning the number of lambs but crossbreeding improved kg lamb weaned per ewe mated (9.2%, P = 0.08) and kg lamb weaned per 100 kg ewe mated (10.0%, P less than 0.05). Among the three native breeds Karakul showed the largest improvement when crossed with the exotic rams for the traits concerning kg lambs weaned. Corriedale and Targhee rams had similar effects on all the traits studied. A lower percentage of virgin ewes showed oestrus, had a lower twinning rate and productivity compared with the mature ones. Sex was not a significant source of variation in lamb livability.

Age Factors↗
PubMed1996

Relationship of production to reproductive performance in Ontario dairy cows: herd level and individual animal descriptive statistics.

Data were collected on reproductive, health and production events in 45 dairy herds distributed throughout southwestern and eastern Ontario. The data were collected between July 1990 and July 1993. The herds were serviced by 11 different veterinary practices. Herd size ranged from 19 to 231 lactating cows, but 90% of the herds consisted of fewer than 125 milking cows. Mean and median actual milk yields per cow per day were 46.0 and 52.3 lbs, respectively, with a minimum of 21.3 and maximum of 67.8 lbs. Mean and medium adjusted corrected milk yields were 56.0 and 62.3 lbs, reflecting mean and median average days in milk of 199.0 and 198.5 d, respectively. Mean and median days in milk at the first estrus were 85.1 and 83.9 d, respectively, at first service 94.0 and 88.9 d, and at conception 126.3 and 115.5 d. Mean and median percentages of days open > 120 were 27.7 and 23.1%, respectively. The mean estrus detection rate was 48.3%, with a minimum of 28.4% and a maximum of 64.2%. The mean first service conception rate was 48.2%, with a minimum of 27.0% and maximum of 72.1%. The mean overall conception rate was 46.7%, with a minimum of 29.8% and a maximum of 70.7%. Mean and median lactation lengths were 341.1 and 338.5 d and the mean and median average dry days were 62.0 and 67.0, respectively. The mean lactational removal rate was 20.6%, with a range of 4.3 to 40.5%. Reasons for culling were available for 1381 cows. Low production accounted for 23.7 % of the cullings; reproductive reasons, 20.6 %; dairy sales, 13.4%; mammary problems, 12.8%; and lameness, 9.9%. Lactational incidence rates for diseases were lower than previously reported for Ontario dairy herds. The most commonly used therapeutic agents were GnRH (10.5%) and PGF (11.7%).

Journal Article↗
PubMed2006

Survey of management practices on reproductive performance of dairy cattle on large US commercial farms.

A survey regarding general management, sire selection, reproductive management, inseminator training and technique, heat abatement, body condition scoring, facility design and grouping, nutrition, employee training and management, and animal health and bio-security was carried out from March to September of 2004 in 153 herds in the Alta Genetics (Watertown, WI) Advantage Progeny Testing Program. A total of 103 herds (67.3%) completed the survey. Herd size was 613 +/- 46 cows, with herds located in Wisconsin (26), California (12), New York (11), Minnesota (10), Michigan (7), Washington (6), Pennsylvania (6), Iowa (5), Idaho (5), Texas (4), Ohio (4), and other states (7). These farms sold 34.5 +/- 0.3 kg of milk/d per cow, with an annual culling rate of 34 +/- 1% and a calving interval of 13.8 +/- 0.1 mo. Cows were observed for estrus 2.8 +/- 0.3 times/d, for a duration of 27 +/- 4 min, but 78% of the respondents admitted that detection of estrus was not the employee's sole responsibility at that time. Managers tried to achieve pregnancy until 8.8 +/- 0.9 failed inseminations, 300 +/- 26 d postpartum, or milk yield <17.7 +/- 0.5 kg/d. Nonpregnant cows were culled at 326 +/- 36 d postpartum or milk yield <16.4 +/- 0.3 kg/ d. Mean durations of the voluntary waiting period were 52 +/- 1.3 and 53 +/- 1.4 d for primiparous and multiparous cows, respectively. Hormonal synchronization or timed artificial insemination programs were used in 87% of the herds, with 86% synchronizing first services, 77% resynchronizing repeat services, and 59% treating cystic, anestrous, or anovular cows. Finding good employees was identified as the greatest labor challenge, followed by training and supervising employees. Mastitis and hairy heel warts were noted as the greatest animal health concerns, followed by lameness, abortions, and death losses, whereas the greatest reproductive challenges were artificial insemination service rate, conception rate, twinning, and retained placenta or metritis. Results of this study can provide a useful benchmark or reference with regard to commonly used management practices on large commercial US dairy farms at the present time.

Animals↗
PubMed1990

Reproductive performance after methotrexate treatment of ectopic pregnancy.

The purpose of this study was to examine return of reproductive potential, hysterosalpingographic findings, and time to conception in patients treated with methotrexate and citrovorum factor for unruptured ectopic pregnancy. Fifty-seven patients with unruptured ectopic pregnancies less than 3.0 cm in greatest dimension were treated with methotrexate and citrovorum factor. The mean time from resolution of the ectopic pregnancy to return of menses was 26.0 (0 to 157) days. Forty-four patients were available for follow-up (2 to 15 months). Nineteen of 23 patients who had hysterosalpingograms demonstrated patency in the ipsilateral tube. Fourteen patients desired pregnancy; 11 of 14 (78.6%) were successful, with 10 of 11 (90.9%) having an intrauterine pregnancy, whereas one of 14 (9.1%) were extrauterine gestations. The mean time from first attempt to achieving pregnancy was 2.3 (1 to 4) months. We conclude that methotrexate and citrovorum factor treatment of unruptured ectopic pregnancy is associated with subsequent tubal patency and does not impair return of menses. Most importantly, the pregnancy rates after this form of therapy appear to be better than those achieved by traditional surgical methods, and are comparable to results after laparoscopic salpingostomy.

Adolescent↗
PubMed1992

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.

Animals↗
PubMed1980

Artificial insemination of individually caged broiler breeders. 1. Reproductive performance of males in relation to age and strain of females.

Studies were conducted to evaluate the reproductive capacity of male broiler breeders used for artificial insemination over an extended period and mated to females of six strains. Biweekly determinations were made of semen volume, semen concentration, and spermatozoal motility for each of the 47 males caged individually from their 39th to 63rd week of age. The percent fertility, duration of fertility, and percent hatchability were determined at five-week intervals (periods) using three young and three force-molted broiler female strains. With young female strains, the mean percent fertility for a 7-day collection of eggs following a single insemination (1 to 7 days) ranged from 95.7 to 81.1 over six consecutive periods. The mean duration of fertility (days) and the mean percent hatchability of fertile eggs was 13.3 and 13.0, and 92.5 and 84.9 respectively, for the first two periods. With force-molted hens, the mean percent fertility (1 to 7 days) ranged between 97.2 and 86.0 over the first three periods, and the mean duration of fertility and the mean percent hatchability was 13.2 and 12.8, and 91.5 and 84.1, respectively, for the first two periods. Fertility of eggs collected for 10 days following a single insemination was slightly but consistently lower than fertility over 7 days for both female groups. Significant differences among males and between periods existed for each semen trait. The effects of male, young female strain and period on fertility and duration of fertility were significant. Hatchability was significantly affected by period only. No male by female strain interaction existed for percent fertility or hatchability. A significant male by period interaction existed for percent fertility, semen volume and concentration. The results obtained are considered to support the feasibility of maintaining broiler breeders in cages and the use of artificial insemination (AI) to produce broiler hatching eggs.

Age Factors↗
PubMed2003

Aspects of reproductive performance in small ruminants--opportunities and challenges.

Ovulation rate is the principal source of variation in the reproductive rate of small ruminants. There is extensive variability in this trait both in terms of major genes and polygenes. Identification of the DNA changes responsible for the Booroola and Inverdale effects enabled testing for these mutations in any population. Surprisingly, in only one of six populations, with segregation of major genes for ovulation rate, could the effect be attributed to one of these mutations. Current evidence shows that there are five distinct loci that have large effects on ovulation rate. Selection on ovulation rate in Finn sheep produced a 2.2-fold change without any evidence for major gene involvement. The response appears to reflect changes in the thresholds that control the number of ova shed, indicating that a fundamentally different mechanism is involved from those shown for Booroola and Inverdale genes, and probably other major genes. The results also indicate that the variability of ovulation rate, for a given mean value, can be reduced by genetic selection. This has direct implications for neonatal survival, which declines rapidly as the size of the litter at birth increases above two - a major limitation on the exploitation of the known major genes. The effectiveness of genetic improvement programmes, especially in sheep, would be greatly enhanced if the problem of poor pregnancy rate from cervical insemination of frozen-thawed semen was solved. Recent studies reveal major differences among ewe breeds and large ram-to-ram variation in pregnancy rate from cervical AI with frozen-thawed semen. Identification of the basis for ram-to-ram variation could be exploited immediately in selecting rams for AI. Progress in this area would greatly facilitate the exploitation of molecular genetic information in the genetic improvement of small ruminants.

Animals↗
PubMed1985

Effect of dietary gestation and lactation protein levels on reproductive performance and body composition of first-litter female swine.

A 2 X 3 factorial split-plot experiment was conducted to determine the effect of dietary protein on the performance and calculated body compositions of 45 first-litter sows using the D2O dilution technique at various reproductive stages. Animals were initially fed 1.82 kg daily of a 14% protein diet to 14 d post-coitum. Subsequently, two gestation protein levels (5 or 14%) were daily fed at 1.82 kg from 15 d postcoitum to parturition with three dietary lactation protein levels (5, 14 or 23%) fed from parturition to 28 d postpartum. Maternal body compositions were determined at 17, 35, 70, 85 and 105 d postcoitum and 7, 14 and 28 d postpartum using prediction equations reported previously. Gravid sows demonstrated higher maternal tissue accretion of all body chemical components from 14 to 70 d than from 70 to 105 d postcoitum. Sows fed the 5% protein gestation diet had more maternal fat but less protein accretion than those fed the 14% protein at each measurement interval. During the last trimester, those sows fed the 5% protein diet catabolized body protein reserves. Gravid sows fed the 14% protein gestation diet catabolized more maternal protein and water between 105 d postcoitum and 7 d postpartum than those fed the 5% protein diet. Litter and pig birth weights were lower and postpartum mortality higher for sows fed the 5% rather than the 14% protein gestation diet. Sows fed the 5% protein lactation diet mobilized more maternal tissue, particularly fat, between 7 and 28 d postpartum than those fed 14 or 23% protein lactation diets. These results suggest that labile maternal body protein reserves are used by gravid and nursing dams to fulfill reproductive needs and that dietary protein sequence affects the dam's performance and body composition.

Animals↗