Gilt development and mating in commercial swine herds with varying reproductive performance

The primary objectives were to improve standard operating procedures for gilt development and mating, based on a comparison of practices among commercial Japanese herds with varying reproductive performance. Questionnaires were sent to 115 herds; the 96 herds (83.5%) responding were classified, on the basis of the upper and lower 25th percentiles of pigs weaned per mated female per year, into high-, intermediate- or low-performing herds. During gilt development, high-performing herds switched to a gilt developer diet at an earlier age than low-performing herds (P < 0.05). More high-performing herds performed first insemination “immediately,” with second insemination “6 to 12 h” after first estrus detection than low-performing herds (P < 0.05). However, there were no differences (P > 0.05) among productivity groups with regard to the use of nutritional flushing or percentage of AI used. In multilevel analyses (17,582 service records), gilts in herds using direct boar contact were 13.73 d younger at first mating than those in the herds using indirect boar contact (P < 0.05), but age was not related to feeding practices or the number of days of boar contact per week (P > 0.05). First-serviced gilts in the herds that performed first insemination “immediately” after first estrus detection had an 8.3 to 8.4% higher farrowing rate (FR) than those in herds that performed first insemination at “6 to 12 h” and “24 h” (P < 0.01). Reserviced gilts in the herds with first insemination “immediately” after first estrus detection had 7.5% higher FR than those in herds with first insemination at “6 to 12 h” (P < 0.05). Meanwhile, first-serviced and reserviced gilts in herds that restricted feed after insemination had 0.23 and 0.17 more pigs born alive (PBA) than gilts in the herds that did not restrict feed (P < 0.05). However, PBA was not related to time of insemination (P > 0.05). In conclusion, to improve gilt reproductive performance, we recommend stimulating gilt estrus by using direct boar contact, performing first insemination “immediately” after first estrus detection, and restricting feed intake after insemination.     

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.     

Economic consequences of reproductive performance in dairy cattle

The net economic value of reproductive efficiency in dairy cattle was estimated using a stochastic dynamic simulation model. The objective was to compare the economic consequences of reproductive performance scenarios (“average” and “poor”) of a cow having a good reproductive performance and to explore which reproductive factors have an important impact on economic efficiency. A “good” reproductive performance scenario was defined with 1 ovulation rate (POVU_i), 0.7 estrus detection rate (PEst), 0.7 conception rate (PCon), 0.03 incidence rate of postpartum disorders prolonging the ovarian cyclicity (CO), 0.2 incidence rate of postpartum disorders reducing conception (ME), 0.05 embryonic death rate (ED), and voluntary waiting period (VWP) of 9 wks pp (post partum). In the current situation of dairy cows in the Netherlands, an “average” reproductive scenario (0.95 POVU_i, 0.5 PEst, 0.5 Pcon, 0.07 CO, 0.27 ME, 0.07 ED and VWP of 12 wks pp) and a “poor” reproductive scenario (0.90 POVU_i, 0.3 PEst, 0.3 Pcon, 0.11 CO, 0.33 ME, 0.09 ED and VWP of 15 wks pp) were identified. A sensitivity analysis was performed by comparing changes of single effect of factors in a good and poor scenario with the average scenario. The mean net economic loss (NEL_i) compared with the good scenario was €34 and €231 per cow per year for the average and poor reproductive performance scenario, respectively. Increasing the calving interval resulted in greater economic loss. The important factors on the cost of reproductive efficiency were the involuntary culling cost and the return of milk production. Variation in PCon, PEst, ME, ED, and VWP had large impacts on economic benefits.     

Seasonal influence on the reproductive performance of swine in the humid zone of Ghana

Relationships between month and climatic factors (ambient temperature, relative humidity, RH, and rainfall) with litter size, conception rate, days from weaning to conception and mortalities at birth and preweaning were studied in large white pigs under research station (RS) and commercial farm (CF) conditions. In RS and CF 868 and 572 farrowing records, respectively, were involved. Litter size was almost evenly distributed in all months of the year, at both farms, despite significant (P<0.05) negative but low correlations between litter size and maximum (r=–0.272, RS) and minimum (r=–0.233, CR) temperatures in the month after conception. There were no significant differences in conception rate between months. However under RS conditions there were significant (P<0.05) correlations between minimum temperature and conception rate in the months prior to (r=–0.362) and at conception (r=–0.221). Days from weaning to conception were bimodally distributed with peak values occurring between January and June and October and December. Significant mortality at birth (P<0.05) and preweaning was generally highest in the cold rainy months of May to October. However, only under CF conditions were there significant correlations between minimum temperature in the month of birth and percentage mortalities at birth (r=–0.217) and preweaning (r=–0.250). Rainfall and RH had no significant (P>0.05) correlation with birth and preweaning mortalities.     

Ovarian luteal activity and reproductive performance of heifers with norgestomet prototype implants

A 122-day trial was conducted with grazing beef heifers (N=120; 14 to 17 months of age) to determine the effects of a silastic Norgestomet prototype implant on heifer weight gain and on the suppression of ovarian luteal activity. The retention rate of the Norgestomet implants and of silastic placebo implants, which were either left untreated, or were topically treated with oxytetracycline, was determined. Medication of the placebo implants with oxytetracycline increased (P < 0.01) implant retention rate at both Day 56 and Day 122. Heifers with Norgestomet implants had higher body weight gains during the last 66 days (P < 0.05), and during the entire 122-day trial (P < 0.07) than heifers with placebo implants. Serum progesterone concentrations on Day 111 or Day 112 indicated a decrease (P < 0.01) in percentage of heifers with ovarian luteal activity on the Norgestomet treatment compared with heifers receiving placebos (23.8% vs 87.7%, respectively). The Norgestomet implant has the potential for suppressing ovarian luteal activity while improving weight gain in beef heifers.     

Effects of fasting ewes before mating on their reproductive performance

Border Leicester x Merino ewes were fasted for the first six days or the second six days of the oestrous cycle preceding mating in the fall season. When not fasting, ewes were grazed with a control group on irrigated pasture. Compared with control ewes, fasting had no effect on oestrous occurrence or fertilization but did reduce the ovulation rate, especially where fasting occurred early in the oestrous cycle.     

Within-farm variability in age structure of breeding-female pigs and reproductive performance on commercial swine breeding farms

This study investigated relationships between herd age structure and herd productivity in breeding herds; it also investigated a pattern in parity proportions of females over 2 years and its relationship with herd productivity in commercial swine herds. This study was based on data from 148 commercial farms in North America stored in the swine database program at the University of Minnesota. The primary selection criterion was fluctuations in breeding-female pig (female) inventories over a 2-year interval. Productivity measurements and parity proportions of females were extracted from the database. A 24-month time-plot in proportions of Parity 0 and Parities 3-5 females (mid-parity) was charted for each farm. Using these charts, a change in proportions of Parity 0 and mid-parity for each farm was categorized into patterns: FLUCTUATE (Parity 0 and mid-parity proportion lines crossed) or STABLE (the two proportion lines never crossed). Higher proportions of mid-parity sows were correlated with greater pigs weaned per female per year (PWFY; P < 0.01). Farms with a FLUCTUATE (73% of the 148 farms) pattern had lower PWFY than those with a STABLE pattern (P < 0.01). The STABLE farms had higher proportions of mid-parity sows, higher parity at culling, higher frequency of gilt deliveries per year, and lower replacement rate than the FLUCTUATE farms (P < 0.01). In conclusion, maintaining stable subpopulations with mid-parity and Parity 0 are recommended to optimize herd productivity.     

Oviposition preferences of the Hessian fly and their consequences for the survival and reproductive potential of offspring

1. The relationship between oviposition preference and offspring performance was investigated experimentally for the Hessian fly Mayetiola destructor (Say) using 10 grass genotypes that represented five different genera and six different species. Oviposition preferences were quantified in a choice test using arrays of 200–400 plants. Offspring performance was estimated by recording survival during three phases of the insect–plant association and by measuring wing length, a correlate of adult reproductive potential. Density effects were examined for all offspring variables, and were taken into account when offspring performance was compared across the 10 grasses. 2. Egg counts from the oviposition choice test revealed a consistent ranking of plants: 18ITSN triticale > Otane bread wheat = Caldwell bread wheat = Stacy bread wheat > 3424 bread wheat = PND durum wheat = Fleet barley = Valetta barley = Matua brome grass > Awapuni oat. 3. Survival and adult wing length varied significantly on the 10 plant types. Survival was ranked: Otane bread wheat > 3424 bread wheat = Fleet barley = Matua brome grass > Caldwell bread wheat = Valetta barley > 18ITSN triticale = PND durum wheat = Stacy bread wheat > Awapuni oat. Adult male and female wing lengths were greatest on Otane, the bread wheat that also provided the best survival. 4. For Hessian flies on each of the 10 plant types, data on survival, wing length, and wing length–fecundity relationships were combined into a single fitness measure. When these fitness measures were compared with egg counts, no overall pattern emerged. On seven of the 10 plant types, there was a positive linear relationship between egg counts and offspring fitness. On the other three plant types, egg counts were high while fitness was low. Possible reasons why Hessian fly females lay eggs on plants that are poor hosts for their offspring are discussed.     

Characterization of swine adiponectin and adiponectin receptor polymorphisms and their association with reproductive traits

In this study, polymorphisms in genes encoding porcine adiponectin (ADIPOQ) and its receptors (ADIPOR1 and ADIPOR2) were evaluated for associations with reproductive traits in a Landrace sow population. Sixteen SNPs were identified, and among these, associations were found between reproductive traits and five SNPs. Heterozygous multiparous females for SNP ADIPOQEF601160:c.178G>A had fewer stillborn piglets (P < 0.05) and shorter weaning-to-oestrus intervals (P < 0.05). Multiparous females bearing the mutant allele for SNP ADIPOQEF601160:c.*1094_1095insC gave birth to fewer stillborn piglets (P < 0.05). In addition, selection for the ADIPOQ [A;C] haplotype is expected to result in multiparous sows having the lowest number of stillborn piglets and shorter weaning-to-oestrus intervals. In second-parity sows, the polymorphism in ADIPOR1 (AY856513:c.*129A>C) showed significant associations with live-born (P < 0.01) and stillborn (P < 0.05) piglets. In multiparous sows, a significant association was observed for an ADIPOR2 polymorphism (AY856514:c.*112G>A), with the c.*112GA genotype associated with shorter weaning-to-oestrus intervals (P < 0.01). Haplotype analyses of ADIPOR2 SNPs revealed that selection in favour of the [A;C] haplotype and against the [G;G] haplotype may result in sows having an increased number of live-born piglets and shorter weaning-to-oestrus intervals. We have therefore described specific SNPs and haplotypes that are associated with large litter size, fewer stillborn and mummified piglets and shorter weaning-to-oestrus intervals. Selection for these SNPs and haplotypes is a strategy to improve reproductive success in pigs.     

Boar culling and mortality in commercial swine breeding herds

The objectives of this study were to measure culling rate and mortality rate of boars; to compare boar life day (BLD: days from birth date to removal date), boar herd life day (BHLD: days from herd entry date to removal date) and herd entry age of boars between high-performing herds and ordinary herds (herd groups); to examine herd measurements for BLD, BHLD and boar age at herd entry; and to observe removal patterns and survival curves for boars by herd groups. This study used 2474 records of individual boars born in 108 herds from 2000 to 2003. Two herd groups were formed on the basis of the upper 25th percentile of pigs weaned per mated female per year (2001-2005). Mixed-effects models and survival analysis were performed. Means of BLD and BHLD (±S.E.M.) were 984 ± 9.5 and 781 ± 8.4 d, respectively. Annualized culling rate and mortality rate were 0.411 and 0.035 boars per 365 BHLD, respectively. Boars in high-performing herds had 51 higher BLD and 62 higher BHLD than those in ordinary herds (P < 0.01). High-performing herds had 32 d lower entry ages than ordinary herds (P < 0.01). Herd measurements such as herd mortality and herd size were not associated with both BLD and BHLD. The hazards in survival analysis were associated with herd groups (P < 0.05). Measurements in the present study provide benchmarks for boar removal in commercial herds.     

A study on reproductive performance and related factors of zebu cows in pastoral herds in a semi-arid area of Tanzania

A prospective longitudinal study was carried out from September 2001 to June 2004 in three adjacent villages in a semi-arid area of Tanzania. The objectives of this study were to measure the intervals between calving and either resumption of cyclical activity or confirmation of pregnancy, to estimate calving intervals, and to investigate the effect of factors assumed to be related to postpartum reproductive performance. A total of 275 lactation periods from 177 Tanzanian Shorthorn Zebu cows managed in a traditional pastoral system in 46 households were initially included. Animals were initially screened for brucelosis and thereafter examined by palpation per rectum at 2-week intervals. Body condition score (scale 1 to 5) was assessed and girth measurement (cm) taken. Occurrence of other reproductive events such as calving, abortion, death of calf, culling and reason for culling were recorded. In a subset of 98 lactation periods from 91 cows milk samples for progesterone (P4) determination were collected twice per week from day 7 after calving to the time of confirmed pregnancy or until milk production ceased before pregnancy. The data were analysed both univariately and in multivariable Cox proportional hazard (frailty) models. The mean (+/-S.E.M.) calving interval was 500+/-13.6 days. Positive reactors in the brucellosis test were 15.6% of the tested animals. Milk P4 analysis showed the rate of abortion/late embryo loss to be 14.3%. Calf mortality rates varied between 14.6 and 17.4%. A positive relationship was found between the outcome variables likelihood of cyclical activity and likelihood of pregnancy in the Cox model, and the explanatory variables: parity and body condition score (BCS) at calving. A negative relationship was found between the outcome variables, and the explanatory variables: maximum BCS loss and calf survival/mortality. Calving in the rainy season was associated with an increased likelihood of pregnancy.     

Ovarian and endocrine responses and reproductive performance following GnRH treatment in early postpartum dairy cows

At calving forty-eight Holstein and Guernsey cows were assigned according to age and breed to one of six postpartum periods (1 or 2, 3 or 4, 5 or 6, 7 or 8, 12 or 13 and 18 or 19 days postpartum). Thirty-six of the cows (6 cows per postpartum period) received a single intramuscular injection of 100 μg GnRH. The other twelve cows (2 cows per postpartum period) served as controls and received a single intramuscular injection of the carrier vehicle for GnRH.Four of 36 cows administered GnRH and three of the 12 control cows ovulated by the day following treatment. Four of the cows were 12 or 13 days postpartum (1 control and 3 GnRH treated) and three were 18 or 19 days postpartum (2 controls and 1 GnRH treated). Six of the seven cows that ovulated the day following treatment had a follicle > 1.0 cm the day prior to treatment. Follicular growth was detected in the earlier postpartum periods but ovulation the following day was not detected for either control or GnRH treated cows. Following estrus or silent estrus, plasma progesterone concentrations increased to about 4 ng/ml on day 13. However, in cows ovulating the day following GnRH treatment, plasma progesterone declined from about 3 ng/ml on day 9 to approximately 1 ng/ml on day 13 postestrus. In addition, LH in plasma was higher (P < .01) ? through 13 days following estrus or silent estrus in cows ovulating the day after GnRH treatment in comparison to cows during the first or subsequent postpartum estrous cycles.In summary, in addition to days postpartum other factors including follicular development and maturity are probably involved in GnRH induced ovulation.     

Population consequences of reproductive decisions

Behaviour can be a key component of animal population ecology yet the population consequences of behavioural decisions are poorly understood. We conducted a behavioural and demographic study of the bitterling Rhodeus sericeus, a freshwater fish that spawns in live unionid mussels. We used a population model incorporating game theory decisions and measurements of demographic parameters in order to provide predictions of population size among 13 populations of this fish. Our model predicted that the observed behavioural spawning decisions, while maximizing individual fitness, cause a significant 6% reduction in population size compared with randomly distributed spawnings. We discuss our findings in the context of the population consequences of adaptive behaviour.     

Synthetic cannabinoids and potential reproductive consequences

Increases in emergency room visits due to abuse of designer drugs, popularly known by the street names “K2” and “Spice,” are a cause for social, judicial, and clinical concerns. The psychoactive components in these herbal drugs mainly consist of different synthetic cannabinoids, and users of these street drugs are primarily within the age group of 12 to 20 years old. The abusive use of synthetic cannabinoids results in anxiety, nausea, vomiting, tachycardia, elevated blood pressure, tremors, seizures, hallucinations, and paranoid behavior, but the effects of maternal use of synthetic cannabinoids during pregnancy are ambiguous due to limited studies in humans and a relative short history of the drugs. In this review, we discuss the known and potential adverse effects of synthetic cannabinoids on human pregnancy using knowledge gathered from studies in mice and limited studies in humans. In mice, multiple sites and stages of pregnancy are potential targets of synthetic cannabinoids, including preimplantation embryo development, oviductal embryo transport, implantation, placentation, and parturition. It is anticipated that maternal use of synthetic cannabinoids would result in severely compromised female fertility and pregnancy outcome.     

Causes and consequences of the evolution of reproductive proteins

Proteins involved in reproduction often evolve rapidly, raising the possibility that changes in these proteins contribute to reproductive isolation between species. We review the evidence for rapid and adaptive change in reproductive proteins in animals, focusing on studies in recently diverged vertebrates. We identify common patterns and point out promising directions for future research. In particular, we highlight the ways that integrating the different but complementary approaches of evolutionary and developmental biology will provide new insights into fertilization processes.     

A retrospective study on effects of storage time of liquid boar semen on reproductive performance in Norwegian swine

The objective of this retrospective field study was to determine the effects of storing, for up to 62 h, heterospermic and homospermic semen in the short-term extender Beltsville thawing solution (BTS), on reproductive performance in Norwegian swine of four different breed combinations. The study was based on fertility records after single or double inseminations with semen collected at an AI station in Norway from January 1998 to June 2001. Increasing the duration of storage of homospermic semen, but not heterospermic semen, from an interval of 4-14 h to an interval of 52-62 h, was associated with a 0.5 piglet reduction in litter size. There were differences in reproductive performance among breed combinations that appeared to be associated with duration of semen storage. In conclusion, prolonged semen storage decreased reproductive performance; the extent varied among breeds and was prevented by the use of heterospermic versus homospermic semen.     

The presence of heterospecific pollen on stigmas of nectariferous and nectarless orchids and its consequences for their reproductive success

Summary The widespread occurrence of nonorchid, heterospecific pollen grains on the stigmatic surfaces of a range of nectariferous and nectarless European orchids (Dactylorhiza. Orchis, Goodyera, andGymnadenia species) is reported for the first time, and the impact of heterospecific pollination on orchid reproductive success is experimentally investigated. There are three main components of stigmatic contamination by heterospecific pollen: the frequency of contamination, the diversity of foreign species present on the stigma, and the amount of pollen deposited. Six out of seven of the species examined have greater than 85% of stigmas contaminated with wind and insect-dispersed pollen. From one to nine insect-dispersed foreign pollen species are present per stigma, including pollen of members of the families Apiaceae, Asteraceae, Caryohpyllaceae, Ericaceae, and Primulaceae. Average loads per stigma vary from 13 to 176 grains, with individual stigma loads ranging from one to 909. Whether or not the orchid provides nectar has a major impact on these three components. Nectarless orchids have the greatest frequencies of contamination, diversity of species, and average load per stigma. Insect-dispersed pollen is deposited both by pollinators and visitors but, in spite of low levels of pollination, nectarless orchids still exhibit higher frequencies of heterospecific pollen contamination. The effect of the presence of heterospecific pollen on the reproductive success of orchids is tested in this study for the first time. Average-to-high, naturally occurring loads of heterospecific pollen derived from a mixture ofArmeria maritima,Caltha palustris,Cochlearia officinalis,Cytisus scoparius, andPrimula vulgaris and consisting of 50–250 grains per load are placed onto stigmas ofDactylorhiza purpurella which are subsequently self-pollinated with half of a pollinium. All pollinations produce capsules indicating that heterospecific pollen does not affect fruit set. Although experimental and control fruits are similar in size, they differ in total seed weight and composition. Total seed weight is reduced and the proportion of seeds with normal embryos decreased while the proportion of unfertilised ovules increased following pollination with heterospecific pollen, indicating a detrimental effect on fertilisation. Lower reproductive success caused by fertilisation failure is likely to be most severe in nectarless species because of their generally higher levels of contaminated stigmas. As nectarless orchids are known to have lower fruit set compared with nectariferous ones, this finding suggests that the reproductive success of nectarless orchids may be even lower than previously realised.Abbreviations RS reproductive success