Reproductive performance of swine females re-serviced after return to estrus or abortion

Artificial insemination and optimization of the use of seminal doses in swine

The optimization of processes associated with artificial insemination (AI) is of great importance for the success of the pig industry. Over the last two decades, great reproductive performance has been achieved, making further significant progress limited. Optimizing the AI program, however, is essential to the pig industry's sustainability. Thus, the aim is not only to reduce the number of sperm cells used per estrous sow but also to improve some practical management in sow farms and boar studs to transform the high reproductive performance to a more efficient program. As productivity is mainly influenced by the number of inseminated sows, guaranteeing a constant breeding group and with healthy animals is paramount. In the AI studs, all management must ensure conditions to the health of the boars. Some strategies have been proposed and discussed to achieve these targets. A constant flow of high-quality and well-managed breeding groups, quality control of semen doses produced, more reliable technology in the laboratory routine, removal of less fertile boars, the use of intrauterine AI, the use of a single AI with control of estrus and ovulation (fixed-time AI), estrus detection based on artificial intelligence technologies, and optimization regarding the use of semen doses from high genetic-indexed boars are some strategies in which improvement is sought. In addition to these new approaches, we must revisit the processes used in boar studs, semen delivery network, and sow farm management for a more efficient AI program. This review discusses the challenges and opportunities in adopting some technologies to achieve satisfactory reproductive performance and efficiency.

Factors associated with specific health, welfare and reproductive performance indicators in pig herds from five EU countries

Production diseases are often of multi-factorial origin in which environment (housing, nutrition and management) health and reproductive challenges show complex interactions. The aim of this study was to identify specific environment-related factors and to discuss their associations with health, welfare and reproductive performance in sows and piglets, in diverse systems using data from 130 farms from five EU countries. Two sets of data were used: a) a questionnaire was developed for sows and piglets covering farm management, interventions and housing and b) farm production data covering various performance parameters. Eight parameters were further selected, four of which were related to sow reproductive performance (litter index, replacement rate, repeat breeding (i.e. failure to breed after one mating), weaning to first mating interval) and the remaining four to litter / piglet health performance (piglets born alive per litter, piglets born dead per litter, preweaning mortality rate and weaned piglets per litter). Univariable and multivariable linear models were employed to identify risk factors. Associations were considered significant if P ≤ 0.007 (a criterion of p ≤ 0.05 corrected for the number of parameters tested). Various risk and protective factors were identified for each tested outcome variable. Country effects were included in all models as a fixed factor. Adjusted R-squared values for the multivariable models varied between 9.6% (preweaning mortality) and 66% (litter index). Litter index (litters/sow/year) was negatively associated with a higher weaning age of the piglets. Housing recently weaned sows to be inseminated in a separate unit from the gestation unit had a positive association with litter index. Repeat breeding was negatively associated with PRRS-free farms, farms that bred (raised) all gilts on the farm and farms that perform farrowing induction of sows. PRRS-free farms were also associated with a higher replacement rate. Farms that bred gilts on the farm and PRRS-free farms were negatively associated with preweaning mortality. Natural ventilation in the gestation unit was associated with fewer piglets born alive and with fewer weaned piglets. Closed type of farms was associated with less piglets born dead. The use of open box housing system for pregnant sows (provision of individual resting areas) was associated with more weaned piglets. In conclusion, several factors related to applying good farm and health management, and optimal housing conditions showed positive association with various sow and piglet performance parameters. Further studies will help to assess causal links for these factors.

Characteristics and risk factors for severe repeat-breeder female pigs and their lifetime performance in commercial breeding herds

BACKGROUND

Repeat-breeder females increase non-productive days (NPD) and decrease herd productivity and profitability. The objectives of the present study were 1) to define severe repeat-breeder (SRB) females in commercial breeding herds, 2) to characterize the pattern of SRB occurrences across parities, 3) to examine factors associated with SRB risk, and 4) to compare lifetime reproductive performances of SRB and non-SRB females. Data included 501,855 service records and lifetime records of 93,604 breeding-female pigs in 98 Spanish herds between 2008 and 2013. An SRB female pig was defined as either a pig that had three or more returns. The 98 herds were classified into high-, intermediate- and low-performing herds based by the upper and lower 25th percentiles of the herd mean of annualized lifetime pigs weaned per sow. Multi-level mixed-effects logistic regression models with random intercept were applied to the data.

RESULTS

Of 93,604 females, 1.2% of females became SRB pigs in their lifetime, with a mean SRB risk per service (± SEM) of 0.26 ± 0.01%. Risks factors for becoming an SRB pig were low parity, being first-served in summer, having a prolonged weaning-to-first-mating interval (WMI), and being in low-performing herds. For example, served gilts had 0.81% higher SRB risk than served sows (P < 0.01). Also, female pigs in a low-performing herd had 1.19% higher SRB risks than those in a high-performing herd. However, gilt age at-first-mating (P = 0.08), lactation length (P = 0.05) and number of stillborn piglets (P = 0.28) were not associated with becoming an SRB female. The SRB females had 14.4-16.4 fewer lifetime pigs born alive, 42.8-91.3 more lifetime NPD, and 2.1-2.2 lower parities at culling than non-SRB females (P < 0.05).

CONCLUSIONS

We recommend that producers closely monitor the female pig groups at higher risk of becoming an SRB.

Seasonal infertility in gilts and sows: Aetiology, clinical implications and treatments

In gilts and sows, the summer-autumn period often is characterized by reduced fertility. Heat stress and long photoperiods during the warm season can cause a reduction in feed intake and an imbalance of the hypothalamic-hypophysial-ovarian axis. The increased variability in the interval between oestrus onset and ovulation results in an increased number of poorly timed inseminations. The altered endocrine activity compromises follicular and corpora luteal development, reduces oocyte quality and increases embryo mortality. This paper reviews current knowledge on the metabolic and endocrine mechanisms associated with seasonal infertility in gilts and sows and describes some pharmacological approaches that can be utilized to counter this infertility.

Recurrence patterns and factors associated with regular, irregular, and late return to service of female pigs and their lifetime performance on southern European farms

A return-to-service occurrence increases nonproductive days of female pigs and decreases herd productivity. The objectives of the present study were 1) to characterize 3 return types based on reservice intervals in female pigs on southern European farms, 2) to determine return risks and recurrence patterns for these types of returns, and 3) to assess lifetime performance of females with the 3 types of returns. We analyzed 653,528 service records and lifetime records of 114,906 females on 125 farms between 2008 and 2013. Reservice intervals were categorized into 3 groups: regular returns (RR: 18 to 24 d), irregular returns (IR: 25 to 38 d), and late returns (LR: 39 d or later). Multilevel generalized linear models were applied to the data. There were 64,385 reservice records (9.9%), with mean risks of RR, IR, and LR per service (±SEM) of 3.6% ± 0.06%, 2.5% ± 0.05%, and 3.0% ± 0.06%, respectively. Of the 43,931 first-returned females, 32.7% had a second return in the same or later parity. Also, 18.8%, 10.2%, and 11.6% of females that had RR, IR, and LR first returns, respectively, had a second return of the same return type. Summer servicing was associated with greater RR, IR, and LR risks in gilts. Also, increased gilt age at first mating was associated with RR ( = 0.03) and LR risk ( < 0.01) but not with IR risk ( = 0.53). For sows, factors associated with greater RR, IR, or LR risks were summer servicing, lower parity, farrowing more stillborn piglets, and having a weaning-to-first-mating interval of 7 d or more ( < 0.01). In lifetime, 33.5% of serviced females had 1 or more returns. These returned females had 41.5 more lifetime nonproductive days than nonreturn females but also 1.9 more lifetime pigs born alive ( < 0.01). We recommend that producers closely monitor females in high-risk groups to reduce their return-to-service intervals.

Herd management procedures and factors associated with low farrowing rate of female pigs in Japanese commercial herds

The objective of the present study was to compare management procedures and production factors between low-farrowing-rate herds (LFR herds) and the remaining herds (Non-LFR herds). The questionnaires were sent to the producers of 115 herds that use the same recording system. The questionnaire requested information about management procedures in 2008: (i) daily frequencies of estrus detection: once or twice a day; and (ii) the timing of first insemination. Data from 93 completed questionnaires (80.9%) were coordinated with the reproductive data of individual female pigs from the recording system. The data included 78,321 service records from 37,777 sows and gilts. Herds were classified into two groups on the basis of the lower 25th percentile of farrowing rate: LFR herds (76.5% or lower) and Non-LFR herds (76.6% or higher). At the herd level, a two-sample t-test, was used to compare the surveyed management procedures between the two herd groups. At the individual level, two-level mixed-effects models were applied, by using a herd at the level two and an individual record at the level one to determine associations between low farrowing rate and management procedures or production factors in gilts and sows. Gilt and sow models were separately constructed. Means (±SEM) of farrowing rate in LFR herds and Non-LFR herds were 71.3±0.92 and 85.5±0.54%, respectively. The lower farrowing rates of gilts and sows in LFR herds were associated with once-daily estrus detection, late timing of first insemination and single mating (P<0.05). In LFR herds that detected estrus only once a day, the farrowing rate decreased by 10.5% in first-serviced gilts and by 4.2% in reserviced sows compared with twice daily estrus detection (P<0.05). However, there was no such association in Non-LFR herds (P>0.05). The LFR herds had higher percentages of single-mated gilts and sows than Non-LFR herds (P<0.05). Fewer LFR herds than Non-LFR herds performed first insemination immediately after first estrus detection for gilts or by 6-12h for sows (P<0.05). In order to improve the farrowing rate in LFR herds, we recommend detecting estrus twice a day and performing first insemination earlier after first estrus detection; immediately for gilts and by 6-12h for sows. Additionally, increasing the percentage of multiple inseminations can effectively improve the farrowing rate.