Current strategies for reproductive management of gilts and sows in North America

Meat quality attributes and oxidation stability of loin chops from finishing gilts and cull sows

The objective of this study was to compare the meat quality attributes, color stability, and lipid oxidation of loin chops from finishing gilts and cull sows in a three-way crossbreeding system: landrace × large white × duroc finishing gilts (n = 20) and landrace × large white sows (n = 20). No significant differences in pH, proximate composition, or total collagen content were found between the two pig groups. However, sow loin chops exhibited different quality characteristics for color, cooking loss, protein solubility, and shear force, in which an increased cooking loss and shear force might be associated with a lower heat-soluble collagen content compared to the gilt loin chops (p < 0.05). Moreover, more rapid changes in redness and chroma during 7 days of aerobic display were observed in the sow loin chops (p < 0.05). Therefore, the results presented here highlight the possibility of issues regarding color and tenderness in sow meat compared to retail pork produced from finishing gilts.

Effects of oestrous synchronization with altrenogest in gilts on endometrial and embryonic characteristics

The use of altrenogest (ALT) supplementation for oestrous synchronization improves subsequent reproductive performance of gilts and sows. However, the causes of this improvement in reproductive performance after ALT treatment are not fully/clearly understood. The objective of this study was to evaluate the effects of ALT supplementation for oestrous synchronization in gilts on the endometrial glands and embryonic development characteristics at 28 days of pregnancy. Pregnant gilts were divided into two experimental treatments: Control (did not receive ALT; n = 9 gilts) and ALT (ALT feeding at 20 mg/day for 18 days; n = 9 gilts). At 28 days of pregnancy, six gilts from each treatment were slaughtered, and reproductive tracts were immediately evaluated. There was no statistical difference (P > 0.05) between treatments regarding ovulation rate, number of embryos, number of vital embryos and number of non-vital embryos. Embryo weight, length and embryonic vesicle weight were lower in ALT treatment compared with Control (P < 0.01), and it was lower in the cervical uterine region compared with apex uterine region, respectively (P < 0.05). Higher values of gland duct area, gland duct perimeter, percentage of the glandular area and total endometrial area were observed in ALT treatment compared with Control (P < 0.05). The use of ALT during 18 days for oestrous synchronization in gilts increased the gland duct area, perimeter and total endometrial area but did not increase the embryo number and embryo size at day 28 of pregnancy.

Comparison of Single, Fixed-Time Artificial Insemination in Gilts Using Two Different Protocols to Synchronize Ovulation

Simple Summary

It is necessary to have a consistent supply of service-ready gilts available to incorporate into each batch of breeding sows. Techniques to manipulate the timing of estrus and possibly the timing of ovulation in gilts are helpful in order to achieve this goal. This study investigated two different techniques for inducing ovulation to allow fixed-time artificial insemination (FTAI) protocols in gilts and compared results with gilts bred when observed in standing heat following cessation of daily altrenogest treatment. Pubertal gilts (n = 180) were assigned to one of three treatment groups. Group 1 gilts (LUT, n = 62) were induced to ovulate utilizing intramuscular injections of equine chorionic gonadotropin followed by porcine luteinizing hormone, and bred using a single FTAI. Group 2 gilts (TRI, n = 61) were induced to ovulate by intravaginal deposition of triptorelin acetate and were bred by a single FTAI. Group 3 gilts (CON, n = 57) were observed for estrus and bred twice (24 h apart) using artificial insemination (AI). LUT and TRI gilts completed farrowing in a smaller window of time compared to CON gilts; however, they also tended to have poorer reproductive performance. LUT and TRI piglets were 80 g and 64 g, respectively, heavier at weaning than CON piglets. Results indicate that FTAI might be useful as a means of minimizing the range in lactation length in a farrowing batch. However, modifications of the protocols may be required to ensure optimum farrowing rates and litter size.

Abstract

In order to efficiently have a consistent supply of service-ready gilts available to incorporate into each batch of breeding sows, it is necessary to manipulate the timing of estrus and possibly the timing of ovulation of gilts. Estrus can be synchronized by the withdrawal of altrenogest after at least 14 days of treatment. It is possible that protocols developed to induce ovulation, and therefore allow fixed-time artificial insemination (FTAI), can improve the predictability of gilt breeding. This study investigated the effect of two FTAI protocols in gilts on reproductive performance and timing of farrowing and piglet weaning weight compared to gilts bred based on signs of estrus after cessation of altrenogest. Puberty was induced in gilts, followed by treatment with altrenogest. Following altrenogest withdrawal, 180 gilts were assigned to one of three treatment groups. Group 1 gilts (LUT, n = 62) were treated with 600 IU equine chorionic gonadotropin 24 h after altrenogest withdrawal and 5 mg porcine luteinizing hormone (pLH) 80 h later, followed by a single FTAI 36 h after pLH. Group 2 gilts (TRI, n= 61) received 2 mL of a gonadotropin-releasing hormone agonist, triptorelin acetate, intravaginally 6 d after altrenogest withdrawal and were bred by a single FTAI 24 h later. Group 3 gilts (CON, n = 57) were observed for estrus and bred twice by AI, 24 h apart. LUT and TRI gilts farrowed closer together (2.4 ± 1.6 and 2.9 ± 1.2 d(days), respectively) compared to CON gilts (4.5 ± 3.3 d). Piglets in LUT were 80 g (p < 0.001) heavier and piglets in TRI were 64 g (p < 0.05) heavier at weaning than CON piglets, when controlling for birth weight. Results indicate that FTAI might be useful as a means of minimizing the time from the first to the last gilt farrowing in a breeding batch of gilts. However, modifications of the protocols may be required to ensure optimum farrowing rates and litter size.

Altrenogest affects expression of galectin-3 and fibroblast growth factor 9 in the reproductive tract of sows

A synthetic progestin altrenogest (ALT) is used to synchronize the estrus cycle of swine for fixed-time artificial insemination (AI) and has been shown to improve follicular development and reproductive performances in post-weaning sows. However, the effects of ALT treatment on reproductive tracts, including the ovaries, oviducts and uterus have not been yet clarified. In this study, we examined the expression of genes involved in endometrial responses in ALT-treated sows. ALT did not significantly alter luteinizing hormone (LH), follicle-stimulating hormone (FSH) and estradiol profiles in blood compared to untreated control. Quantitative RT-polymerase chain reaction (qRT-PCR) analysis showed that the expression of genes encoding galectin-3 (LGALS3) and fibroblast growth factor 9 (FGF9) was upregulated in the reproductive tracts of ALT-treated sows, including the ovaries, oviducts and uteri. Moreover, ALT treatment induced the expression of FGF9 and galectin-3 proteins, and promoted their localization to the luminal epithelium of the oviducts and uterus. Our findings suggest that the enhancement of reproductive performance shown by ALT-treated sows is associated with the upregulation of galectin-3 and FGF9, which are essential for endometrial receptivity, successful implantation, and pregnancy.

Neonatal lactocrine deficiency affects the adult porcine endometrial transcriptome at pregnancy day 13

Reproductive performance of female pigs that do not receive sufficient colostrum from birth is permanently impaired. Whether lactocrine deficiency, reflected by low serum immunoglobulin immunocrit (iCrit), affects patterns of endometrial gene expression during the periattachment period of early pregnancy is unknown. Here, objectives were to determine effects of low iCrit at birth on the adult endometrial transcriptome on pregnancy day (PxD) 13. On the first day of postnatal life, gilts were assigned to high or low iCrit groups. Adult high (n = 8) and low (n = 7) iCrit gilts were bred (PxD 0), and humanely slaughtered on PxD 13 when tissues and fluids were collected. The endometrial transcriptome was defined for each group using mRNAseq and microRNAseq. Reads were mapped to the Sus scrofa 11.1 genome build. Mature microRNAs were annotated using miRBase 21. Differential expression was defined based on fold change (≥ ±1.5). Lactocrine deficiency did not affect corpora lutea number, uterine horn length, uterine wet weight, conceptus recovery, or uterine luminal fluid estrogen content on PxD 13. However, mRNAseq revealed 1157 differentially expressed endometrial mRNAs in high versus low iCrit gilts. Differentially expressed genes had functions related to solute transport, endometrial receptivity, and immune response. Six differentially expressed endometrial microRNAs included five predicted to target 62 differentially expressed mRNAs, affecting similar biological processes. Thus, lactocrine deficiency on the first day of postnatal life can alter uterine developmental trajectory with lasting effects on endometrial responses to pregnancy as reflected at the level of the transcriptome on PxD 13.

Herd-level factors associated with piglet weight at weaning, kilograms of piglets weaned per sow per year and sow feed conversion

To understand the production factors that affect conclusive parameters of sow herd performance can improve the use of the resources and profitability of farm. The objective of this study was to identify associations and quantify the effects of a set of factors related to piglet weight at weaning (PWW), kilograms of piglets weaned per sow per year (kgPWSY) and sow feed conversion (SFC). Data from 150 farms were collected, for a total study population of 135 168 sows, including gilt replacement, breeding (mating), gestation and farrowing/lactation phases. A questionnaire focusing on reproductive performance, management, facilities, feeding, health and biosafety was administered. Multiple linear regression models were used to assess associations among factors with each of the three dependent variables. Increased duration of lactation was positively associated with PWW, kgPWSY and SFC. The increase in the number of live born pigs per litter was positively associated with kgPWSY and with SFC. Farms with higher PWW had farrowing room humidifiers, did not surgically castrate male piglets and used quaternary ammonia compounds for farrowing room disinfection. Farms with higher kgPWSY used lined ceilings in farrowing rooms and winter feeds with higher CP percentages in gestation; they also had more farrowings per sow per year. Sow feed conversion was worse in farms with partly slatted floors during gestation, in farms feeding lactating sows six times a day or ad libitum and farms with a higher sow-handler ratio. This study indicates that farms can increase PWW and kgPWSY and improve the SFC by changing one or more management, biosafety and feeding practices or facilities as well as by focusing on improving several performance parameters, particularly increasing the duration of lactation and the number of live born pigs per litter.

Comparison of single, fixed-time artificial insemination in weaned sows using 2 different protocols to synchronize ovulation

The present study evaluated 2 fixed-time artificial insemination (FTAI) techniques in sows in 2 herds. At weaning, sows were assigned to 1 of 3 treatment groups: Group 1 received intramuscular injections of 600 IU of equine chorionic gonadotropin followed 3 days later by 5 mg of porcine luteinizing hormone; Group 2 received a 200-μg intravaginal dose of triptorelin acetate 4 days post-weaning; and Group 3 were heat checked daily and double-mated when observed in heat. Groups 1 and 2 were bred once at a fixed-time independent of estrous behavior. Time of ovulation was monitored by ultrasound in a subset of sows from each group. Both FTAI techniques resulted in sows farrowing within short intervals, leading to the weaning of pigs that tended to be older and heavier compared with controls. The use of FTAI, however, was associated with a trend to reduced reproductive performance compared with controls in 1 herd.

Effects of fixed-time artificial insemination using triptorelin on the reproductive performance of pigs: a meta-analysis

Triptorelin (TRI), a gonadotropin-releasing hormone agonist allowing ovulation synchronization in pigs, is indispensable for fixed-time artificial insemination (FTAI) protocols. However, the effect of FTAI using TRI (FTAI-TRI) on the reproductive performance is controversial. We performed a meta-analysis to determine whether FTAI-TRI affects reproductive performance of pigs, including pregnancy rate (PR), number of pigs born alive per litter (NBA), farrowing rate (FR) and total number of pigs born per litter (TNB). A total of 37 trials from 15 studies were extracted and analysed in Stata. A weighted mean difference (WMD) with 95% confidence interval (CI) was calculated for NBA and TNB, and risk ratio (RR) with 95% CI was calculated for PR and FR. Pregnancy rate, TNB and NBA data were applied to a fixed-effect protocol, and FR data were applied to a random-effect protocol. We found that for weaned sows, the FTAI-TRI group had comparable reproductive performance to the artificial insemination (AI) following oestrus detection (EDAI) group. Fixed-time AI has many advantages, including the elimination of the need to heat-check twice daily, so that FTAI-TRI is a good substitute for EDAI. Subgroup analysis indicated that the optimal timing of triptorelin treatment was 96 h after weaning, which gave significant positive effects on PR (RR = 1.08, P = 0.000) and non-significant positive effects on TNB (WMD = 0.12, P = 0.452). Triptorelin at a dose of 100 μg showed better effects than 200 μg, with significant positive effects on PR (RR = 1.09, P = 0.005) and FR (RR = 1.06, P = 0.036). So a single dose of 100 μg was recommended. The optimal protocol was insemination at 24 h and again at 48 h after triptorelin administration if they remained in standing oestrus, and this provided a significantly higher NBA (WMD = 0.59, P = 0.013) that increased by 0.59. For gilts, the FTAI-TRI group showed decreased (not significant) PR (RR = 0.96, P = 0.127) and significantly decreased FR (RR = 0.93, P = 0.013), TNB (WMD = -0.85, P = 0.006) and NBA (WMD = -0.98, P = 0.000), which were inferior to those in the EDAI group. In conclusion, the effects of FTAI-TRI on the reproductive performance of pigs were parity-, treatment timing-, insemination timing-, and dosage-dependent. Fixed-time AI using triptorelin could effectively replace the EDAI protocol for sows, but not for gilts.

Analysis of survey data of breeding herd for reproductive management practices in swine farms of Punjab

The present survey was performed to analyze standard operating procedures for swine development and fertility based on prevailing reproductive management practices among different swine farms of Punjab. The average farrowing rate, farrowing interval, weaning to estrus interval, weaning to conception interval and age at first breeding were 71.5±11.4%, 165.4±13.8 days, 8.3±2.1 days, 42.7±11.0 days and 8.1±1.3 months, respectively. Mean live litter size at birth and weaning were 9.9±3.6 and 8.1±3.3 piglets per farrowing, respectively. Most farmers (94.1%) kept pigs in loose housing system with a mixture of both stalls and pens, and used cement and brick as construction material for sties. Majority of farms (84.3%) functioned as farrow to wean with intensive production systems (75.5%). The labor to animal ratio of 1:50 was most common. Accurate and well maintained records were noticed at 66.7% farms. Start of boar exposure after weaning began within 1 day, occurring most often in morning, with exposure times varying from < 2–5 min/sow in 87.3% farms. Natural mating was allowed within minutes to hours after detection of estrus on 100% of farms. At all farms (100%), sows were allowed 􀁴1 chance for breeding after conception failure before culling. Summer infertility was observed on 56.9% of farms. Feeding method for lactating sows was divided between ad lib. and gradual daily increase of concentrate feed and kitchen waste. None of the farmer practiced docking in newborn piglets. These results suggest that reproductive management of farms in key areas related to weaning, breeding, gestation, feeding and health care could be a source of varying reproductive performance among swine.

The impact of dietary supplementation of arginine during gestation in a commercial swine herd: I. Gilt reproductive performance

Supplemental arginine (Arg) during gestation purportedly benefits fetal development. However, the benefits of a gestational Arg dietary strategy in commercial production are unclear. Therefore, the objectives of this study examined Arg supplementation during different gestational stages and the effects on gilt reproductive performance. Pubertal gilts (n = 548) were allocated into 4 treatment groups: Control (n = 143; 0% supplemental Arg) or 1 of 3 supplemental Arg (1% as fed) treatments: from 15 to 45 d of gestation (n = 138; Early-Arg); from 15 d of gestation until farrowing (n = 139; Full-Arg); or from 85 d of gestation until farrowing (n = 128; Late-Arg). At farrowing, the number of total born (TB), born alive (BA), stillborn piglets (SB), mummified fetuses (MM), and individual piglet birth weights (BiWt) were recorded. The wean-to-estrus interval (WEI) and subsequent sow reproductive performance (to third parity) were also monitored. No significant effect of supplemental Arg during any part of P0 gestation was observed for TB, BA, SB, or MM (P ≥ 0.29). Offspring BiWt and variation among individual piglet birth weights did not differ (P = 0.42 and 0.89, respectively) among treatment groups. Following weaning, the WEI was similar among treatments (average of 8.0 ± 0.8 d; P = 0.88). Litter performance over 3 parities revealed a decrease (P = 0.02) in BA for Early-Arg fed gilts compared with all other treatments, whereas TB and WEI were similar among treatments over 3 parities (P > 0.05). There was an increased proportion of sows with average size litters (12 to 16 TB) from the Full-Arg treatment sows (76.8% ± 3.7%) when compared with Control (58.7% ± 4.2%; P = 0.01); however, the proportion of sows with high (>16 TB) and low (<12 TB) litters was not different among treatments (P = 0.20). These results suggest that gestational Arg supplementation had a minimal impact on reproductive performance in first parity sows. These data underscore the complexity of AA supplementation and the need for continued research into understanding how and when utilizing a gestational dietary Arg strategy can optimize fetal development and sow performance.

The impact of dietary supplementation of arginine during gestation in a commercial swine herd: II. Offspring performance

Arginine (Arg) is an important amino acid of pig fetal development; however, whether Arg improves postnatal performance is ill-defined. Therefore, the influence of Arg supplementation at different gestational stages on offspring performance was evaluated in a commercial swine herd. Sows (n = 548) were allocated into 4, diet by stage of gestation treatments: Control (n = 143; 0% suppl. Arg), or dietary treatments supplemented with 1% L-Arg (free-base; Ajinomoto Animal Nutrition North America, Inc., Chicago, IL): from 15 to 45 d of gestation (n = 138; Early-Arg); 15 d of gestation to farrowing (n = 139; Full-Arg); and from day 85 of gestation to farrowing (n = 128; Late-Arg). All offspring were individually identified and weighed at birth; at weaning, a subset was selected for evaluation of carcass performance at market. All data were analyzed using birth weight (BiWt) and age as covariates. Wean weights (WW) and prewean (PW) ADG tended to increase (P = 0.06) in progeny from sows supplemented with Arg, as compared to progeny from Control sows. Preplanned contrast comparisons revealed an increased (P = 0.03) BiWt for pigs from sows receiving 1% L-Arg prior to day 45 of gestation (Early-Arg and Full-Arg; 1.38 kg/pig), as compared to pigs from sows not supplemented prior to day 45 of gestation (Control and Late-Arg; 1.34 kg/pig). No difference in BiWt was observed (1.36 kg/pig; P = 0.68) for Arg supplementation after day 85 of gestation (Full-Arg and Late-Arg), as compared to those not receiving Arg supplementation after day 85 (Control and Early-Arg); although WW and PW ADG were greater (P = 0.02), respectively. A 3.6% decrease (P = 0.05) in peak lean accretion ADG occurred when dams received 1% L-Arg prior to day 45 of gestation (Early-Arg and Full-Arg), however, no other significant differences were detected in finishing growth parameters or carcass characteristics (P ≥ 0.1). Pig mortality rates tended (P = 0.07) to decrease in progeny of dams supplemented Arg after day 85 (3.6%) compared to dams not provided additional Arg during late gestation (4.9%). Collectively, these data suggest that Arg provided during late gestation may improve WW and PW ADG, however, finishing performance was not affected. While Arg supplementation provided some moderate production benefits, further investigation is warranted to comprehensively understand the gestational timing and biological role of Arg supplementation during fetal and postnatal development in commercial production systems.

Combining Fixed-Time Insemination and Improved Catheter Design in an Effort to Improve Swine Reproduction Efficiency

Conventional practice is to breed sows by artificial insemination (AI) at least twice using approximately three billion sperm per insemination upon estrus at standing heat. This research explored the use of combined technologies, including fixed-time insemination (FTAI) and an alternative catheter design that reportedly reduces semen backflow, in order to reduce the number of inseminations and the semen dosage and maintain reproductive efficiency. The FTAI technique used in this study was to inject I.M. 600 IU equine chorionic gonadotropin (eCG) at weaning and 5 mg porcine luteinizing hormone (pLH) to stimulate ovulation 80 h later, followed by a single insemination 36 h after the pLH injection. The two catheters used in this study were a conventional foam-tipped insemination catheter and a Gedis catheter. The Gedis catheter is designed to be completely inserted into the vagina. The semen is enclosed along the length of the rod and held in place by a gel cap that melts when inserted into the cervix. Sows were assigned to the following treatments: Group 1 (n = 135), bred twice with a conventional catheter and a standard semen dose of approximately three billion sperm in 80 mL; Group 2 (n = 123), FTAI with conventional catheter and a standard semen dose; Group 3 (n = 127), FTAI with Gedis catheter and a standard semen dose; Group 4 (n = 126), FTAI with Gedis catheter and a reduced semen dose with one billion sperm. The farrowing rates were 81.6%, 77.7%, 74.0%, and 62.7% for Groups 1 to 4, respectively. The likelihood of farrowing was lower for Group 3 and Group 4 compared to Group 1 (odds ratio (OR) = 0.57; p = 0.08 and OR = 0.35; p = 0.001, respectively). Likewise, litter size of Group 3 and Group 4 was smaller than Group 1 (p = 0.006 and p = 0.04, respectively). Overall, the combination of Gedis catheter and FTAI resulted in decreased reproductive performance that outweighed the value of using less semen.

Induction of parturition by double administration of prostaglandin F2α in sows reduces the variation of gestation length without affecting the colostrum yield and piglet performance

The objective of the present study was to investigate whether double intra-vulvo submucosal administration of prostaglandin F2α (PGF2α) could improve farrowing synchronization compared to single administration, and the effects of the induction of farrowing on colostrum yield and piglet performances. In total, 91 sows were randomly assigned to one of three groups: i) treatment with a single or ii) double administration of PGF2α or iii) control group without any treatment. A synthetic analogue of PGF2α was administrated via the intra-vulvo submucosal route on day 114 of gestation, at 0800 hr (single administration) or at 0800 and 1400 hr (double administration). The animals were monitored during the farrowing process. The time interval from the first administration of PGF2α to the onset of parturition was compared between groups. The proportion of sows that farrowed within 32 hr of induced parturition was higher in the double administration group than in the single administration group (100 vs. 84.4%, P=0.046). The duration of farrowing was higher in single administration sows than in control (241.1 vs. 169.5 min, P=0.004) and tended to be higher than in double administration sows (241.1 vs. 190.3 min, P=0.088). Birth interval of piglets born after double administration of PGF2α was shorter than those born after a single administration (14.6 and 20.1 min, P=0.024). In sows, the induction of parturition using a double administration of PGF2α reduces variation in gestation length and significantly increases the proportion of sows with an early response to PGF2α.

Review: Maternal programming of development in the pig and the lactocrine hypothesis

Maternal effects on development are profound. Together, genetic and epigenetic maternal effects define the developmental trajectory of progeny and, ultimately, offspring phenotype. Maternally provisioned environmental conditions and signals affect conceptus, fetoplacental and postnatal development from the time of conception until weaning. In the pig, reproductive tract development is completed postnatally. Porcine uterine growth and uterine endometrial development occur in an ovary-independent manner between birth (postnatal day = PND 0) and PND 60. Milk-borne bioactive factors (MbFs), exemplified by relaxin, communicated from lactating dam to nursing offspring via a lactocrine mechanism, represent an important source of extraovarian uterotrophic support in the neonatal pig. Lactocrine deficiency from birth affects both the neonatal porcine uterine developmental program and trajectory of uterine development, with lasting consequences for endometrial function and uterine capacity in adult female pigs. The potential lactocrine signaling window extends from birth until the time of weaning. However, it is likely that the maternal lactocrine programming window - that period when MbFs communicated to nursing offspring have the greatest potential to affect critical organizational events in the neonate - encompasses a comparatively short period of time within 48 h of birth. Lactocrine deficiency from birth was associated with altered patterns of endometrial gene expression in neonatally lactocrine-deficient adult gilts during a critical period for conceptus-endometrial interaction on pregnancy day 13, and with reduced litter size, estimated at 1.4 pigs per litter, with no effect of parity. Data were interpreted to indicate that reproductive performance of female pigs that do not receive sufficient colostrum from birth is permanently impaired. Observations to date suggest that lactocrine-dependent maternal effects program postnatal development of the porcine uterus, endometrial functionality and uterine capacity. In this context, reproductive management strategies and husbandry guidelines should be refined to ensure that such practices promote environmental conditions that will optimize uterine capacity and fecundity. This will entail careful consideration of factors affecting lactation, the quality and abundance of colostrum/milk, and practices that will afford neonatal pigs with the opportunity to nurse and consume adequate amounts of colostrum.

Effects of N-carbamylglutamate and arginine on steroidogenesis and proliferation of pig granulosa cells in vitro

Results of in vivo studies indicate dietary N-carbamylglutamate (NCG) and arginine (ARG) can enhance reproductive performance in gilts. It was hypothesized that both NCG and ARG will alter hormone-induced estradiol (E2) production by granulosa cells (GC), explaining why these compounds could improve reproductive performance in pigs. The objective of these studies, therefore, was to evaluate the direct effects of NCG and ARG on porcine GC proliferation and steroidogenesis, using an in vitro cell culture system. The GC from small (SM; 1-5 mm) and large (LG; >5 mm) pig follicles were cultured for 2 days in 5% fetal bovine serum and 5% porcine serum-containing medium followed by 2 days in serum-free medium containing 500 ng/mL of testosterone (as an E2 precursor), and NCG or ARG at various doses in the presence of either follicle-stimulating hormone (FSH; 30 ng/mL), insulin-like growth factor-1 (IGF1; 30 ng/mL), or both. Numbers of GC were determined at the end of the experiment and concentrations of progesterone (P4) and E2 in culture medium were determined. Results indicated that LG-follicle GC were more responsive to NCG and ARG than SM-follicle GC. Specifically, in LG-follicle GC, NCG inhibited (P <  0.05) basal and FSH-induced P4 and E2 production but stimulated cell numbers; whereas ARG inhibited FSH-induced E2 production and cell numbers. In SM-follicle GC, treatment with NCG and ARG decreased IGF1 plus FSH induced P4 production, but E2 production and cell proliferation were not affected. These studies indicate that NCG and ARG may directly affect follicular function in pigs.

Gilt Management for Fertility and Longevity

Simple Summary

Improving sow lifetime productivity, herd stability, and maximizing lifetime performance and longevity in the sow herd, represent significant challenges to the swine industry. Routine implementation of efficient gilt development unit (GDU) programs which deliver high quality, breeding-eligible gilts to the sow farm is still needed. Good gilt management starts at birth, because litter of origin, lactation management and the application of early selection strategies are early indicators of future performance and efficiency. A failure to select gilts with the greatest reproductive potential and inappropriate management of their physiological state and metabolic condition at service, are key risk factors for poor sow lifetime productivity (SLP). Management practices that deliver gilts with the greatest potential SLP are crucial to the productivity of conventional production systems.

Abstract

Substantial evidence supports successful management of gilts as an absolutely necessary component of breeding herd management and the pivotal starting point for the future fertility and longevity of the breeding herd. Therefore, gilt management practices from birth have the potential to influence the future reproductive performance of the sow herd. A good gilt management program will address several key components such as birth traits that determine the efficiency of replacement gilt production; effective selection of the most fertile gilts for entry to the breeding herd; effective management programs that provide a consistent supply of service eligible gilts; and appropriate management of weight, physiological maturity, and a positive metabolic state at breeding. Good gilt management can largely resolve the existing gap between excellent genetic potential and the more modest sow lifetime productivity typically achieved in the industry. Investment in good gilt development programs from birth represents a foundational opportunity for improving the efficiency of the pork production industry.

Pharmacokinetics of altrenogest in gilts

Altrenogest, a synthetic progestogen, is characterized by its estrus synchronization in mares, ewes, sows, and gilts. To investigate the pharmacokinetic profile and evaluate its accumulation in gilts, 18 oral doses of 20 mg altrenogest/gilt/day were given to eight healthy gilts at an interval of 24 hr. Plasma samples were collected, and altrenogest was determined by ultra-high-performance liquid chromatography with mass spectrometry. WinNonlin 6.4 software was used to calculate the pharmacokinetic parameters through noncompartmental model analysis. After the first administration (D 1), the pharmacokinetic parameters, including T_max , C_max , and the elimination half-life (T_1/2λz ), were similar to those observed after the final administration (D 18). However, the mean residence time at D 1 was significantly lower than D 18. As a whole, the mean steady-state plasma concentration (C_ss ), degree fluctuation (DF), accumulation factor (R_ac ), and area under the plasma concentration-time curve in steady state (AUC_ss ) were 22.69 ± 6.15 ng/ml, 270.64 ± 42.51%, 1.53 ± 0.23, and 544.63 ± 147.49 ng hr/ml, respectively. These results showed that after 18 consecutive days of oral administration of altrenogest, plasma concentrations of altrenogest had a certain degree of fluctuation, without significant accumulations.

Effects of dietary energy and protein levels on reproductive performance in gestating sows and growth of their progeny

This experiment was conducted to evaluate the effect of dietary energy and crude protein (CP) levels on reproductive performance, litter performance, milk quality, and blood profiles in gestating sows. A total of 59 multiparous sows (Yorkshire × Landrace) with similar body weights (BW), backfat thickness (BF), and parity were assigned to one of six treatments with 9 or 10 sows per treatment using a 2 × 3 factorial arrangement and completely randomized design. The first factor was two levels of dietary metabolizable energy (ME) density (13.40 or 13.82 MJ/kg) and the second factor was three dietary protein levels based from 35 day in gestating phases (10.5%, 12%, and 13.5%). Backfat thickness change in lactating sows decreased linearly as CP level increased (p = 0.03). Increased energy level in the gestating sow diet tended to increase the total number of piglets born (p = 0.07), but piglet weight decreased (p = 0.02). Dietary CP level had a negative effect on colostrum quality. Casein, protein, total solid, and solids-not-fat concentrations decreased linearly and lactose level increased linearly as CP level in the gestating sow diet increased (casein%: p = 0.03; protein%: p = 0.04; lactose%: p = 0.06; total solids: p = 0.03; solid-not-fat: p = 0.03, respectively). However, improving ME by 0.42 MJ/kg had no significant effect on the chemical composition of sow colostrum. There were no significant differences in blood glucose concentration in gestating sows when sows were fed different levels of energy during gestation, but blood glucose increased at 21 day of lactation when energy increased by 0.42 MJ/kg (p = 0.04). Blood urea nitrogen concentration increased linearly when dietary CP levels increased at 110 day in gestation, 24-hours postpartum, and 21 days of lactation (linear, p < 0.05, p < 0.05, and p < 0.05, respectively), and it also increased when dietary energy increased at 110 days of gestation and 24-hours postpartum (p < 0.01, and p < 0.01, respectively). A gestating sow diet containing 13.82 MJ/kg ME and 10.5% CP can improve reproductive performance, litter performance, and colostrum quality.

Investigating causal biological relationships between reproductive performance traits in high-performing gilts and sows1

Efficient management of swine production systems requires understanding of complex reproductive physiological mechanisms. Our objective in this study was to investigate potential causal biological relationships between reproductive performance traits in high-producing gilts and sows. Data originated from a nutrition experiment and consisted of 200 sows and 440 gilts arranged in body weight blocks and randomly assigned to dietary treatments during late gestation at a commercial swine farm. Reproductive performance traits consisted of weight gain during late gestation, total number born and number born alive in a litter, born alive average birth weight, wean-to-estrous interval, and total litter size born in the subsequent farrowing. Structural equation models combined with the inductive causation algorithm, both adapted to a hierarchical Bayesian framework, were employed to search for, estimate, and infer upon causal links between the traits within each parity group. Results indicated potentially distinct reproductive networks for gilts and for sows. Sows showed sparse connectivity between reproductive traits, whereas the network learned for gilts was densely interconnected, suggesting closely linked physiological mechanisms in younger females, with a potential for ripple effects throughout their productive lifecycle in response to early implementation of tailored managerial interventions. Cross-validation analyses indicated substantial network stability both for the general structure and for individual links, though results about directionality of such links were unstable in this study and will need further investigation. An assessment of relative statistical power in sows and gilts indicated that the observed network discrepancies may be partially explained on a biological basis. In summary, our results suggest distinctly heterogeneous mechanistic networks of reproductive physiology for gilts and sows, consistent with physiological differences between the groups. These findings have potential practical implications for integrated understanding and differential management of gilts and sows to enhance efficiency of swine production systems.

Relaxin and the 'Milky Way': The lactocrine hypothesis and maternal programming of development

Maternal effects on early postnatal development in mammals are mediated, in part, by milk-borne bioactive factors transmitted from mother to nursing offspring. The term 'lactocrine' was coined to describe this mode of signaling. Relaxin (RLX), one of a family of neohormones found in mammals, is detectable in milk from multiple species. In the pig, evidence of bioactive proRLX in colostrum/milk, immunoreactive RLX in the circulation of nursed neonates, and RLX receptor expression in RLX-sensitive neonatal female reproductive tract tissues, established RLX as a prototypical lactocrine-active factor. Observations provided the foundation for the lactocrine hypothesis for maternal programming of postnatal development. Studies designed to test the lactocrine hypothesis provided insights into both short-term effects of milk-borne bioactive factors in the neonate, and long-term consequences of maternal lactocrine programming of endometrial function and fecundity in adults. Thus, RLX led to the 'Milky Way'.

Effect of feeding frequency and sow parity based on isocaloric intake during gestation on sow performance

The aim of this study was to investigate the effect of feeding frequency and sow parity based on same rate of maintenance energy intake during gestation on sow performance. One hundred and seventy-seven sows [Topigs Norsvin 70, Landrace × Large White, Topigs Norsvin USA, Burnsville, MN; parity 3.80 ± 0.16; initial BW = 211.34 ± 3.37 kg; backfat (BF) 13.57 ± 0.54 mm] were blocked by parity, balanced for BW, and randomly assigned to 1 of 3 treatments in a randomized complete block design. Treatments included sows fed corn-soybean meal-based diet 1× daily at 0730 h (control, T1), 2× daily [half ration at 0730 and 1530 h (T2)], or 3× daily [a third portion at 0730, 1130, and 1530 h (T3)], with daily feed quantity kept at 1.25 × maintenance energy intake [100 × (BW)0.75] kcal ME/d. Treatments were imposed from day 30 of gestation. Sows received on average 6,921, 7,129, and 7,399 kcal ME/d from days 30 to 60, days 61 to 90, days 91 to 109 of gestation, respectively. Feeding frequency during gestation had no effect on lactation ADFI (P > 0.10). Sows fed 3× daily during gestation had improved lactation G:F (P = 0.040) compared with sows fed 2× but similar to control sows (P = 0.338). Treatment did not alter BW or BW variations during gestation, lactation, or from days 30 to wean (P > 0.10). Sows fed 2× daily had tendency to gain BF from day 30 to day 109 of gestation (P = 0.053) but tended to lose BF during lactation (P = 0.091) relative to the control sows. Feeding frequency (2× and 3× daily) tended to increase the number of piglets weaned by 0.40 (P = 0.056) and 0.53 (P = 0.098) piglets, respectively, compared with control sows. Sows fed 2× daily during gestation had reduced number of stillborn relative to control sows (P = 0.035). From day 30 to wean, gilts had propensity to lose BF relative to P1+ (P = 0.094), but lost BF compared with P3+ and P6+ sows (P = 0.003). Parity P6+ sows had highest percentage of both 72 h and preweaning piglet mortality than P0, P1+, and P3+ sows (P < 0.05). In conclusion, parity (P6+) had greater lactation BW gain but higher mortalities relative to lower parity sows. Sows fed 2× daily tended to gain BF from days 30 to 109 of gestation and had reduced number of stillborn relative to control sows. It appears that increasing gestation sow feeding frequency from 1× daily to 2× and 3× daily may reduce the number of stillborn and increase litter size at weaning although most of the reproductive traits were not affected.

Development and Function of Uterine Glands in Domestic Animals

All mammalian uteri contain glands that synthesize or transport and secrete substances into the uterine lumen. Uterine gland development, or adenogenesis, is uniquely a postnatal event in sheep and pigs and involves differentiation of glandular epithelium from luminal epithelium, followed by invagination and coiling morphogenesis throughout the stroma. Intrinsic transcription factors and extrinsic factors from the ovary and pituitary as well as the mammary gland (lactocrine) regulate uterine adenogenesis. Recurrent pregnancy loss is observed in the ovine uterine gland knockout sheep, providing unequivocal evidence that glands and their products are essential for fertility. Uterine gland hyperplasia and hypertrophy during pregnancy are controlled by sequential actions of hormones from the ovary and/or pituitary as well as the placenta. Gland-derived histotroph is transported by placental areolae for fetal growth. Increased knowledge of uterine gland biology is expected to improve pregnancy outcomes, as well as the health and productivity of mothers and their offspring.

A new device for deep cervical artificial insemination in gilts reduces the number of sperm per dose without impairing final reproductive performance

Background

The aim of this study was to evaluate the reproductive performance of a new artificial insemination (AI) device specifically designed for gilts (Deep cervical AI, Dp-CAI) by means of which the sperm is deposited deeply in the cervix (8 cm more cranial than in traditional cervical insemination-CAI). New AI techniques have arisen in recent decades in the porcine industry, such as post-cervical artificial insemination (PCAI), which involves depositing the sperm in the body of the uterus [through a catheter (outer tube)-cannula (inner tube)] rather than by CAI. Although the PCAI method has been successfully applied in farm conditions to reduce sperm doses without impairing the reproductive performance, this technique has limitations in gilts mainly because of the difficulty involved in introducing the inner cannula through the cranial part of the cervix. For this reason, the Dp-CAI method described herein may be considered as an alternative to CAI and PCAI methods in gilts.

Results

Gilts were divided in two experimental groups: 1) Dp-CAI: gilts (n = 1166) inseminated using 1.5 × 10⁹ sperm/45 mL; 2) CAI (as a control group): gilts (n = 130) inseminated using 2.5 × 10⁹ sperm/85 mL. The Dp-CAI method was successfully applied in 88.90% of the gilts, with no differences detected between gilts with 1 or 2 previous oestrus cycles, although the catheter could be introduced more deeply in 2 oestrus gilts (P < 0.05). As the length of the insemination device that could not be introduced increased (at the moment of insemination), so the success rate of the Dp-CAI device fell, as did the total number of piglets born. When the reproductive output in CAI and Dp-CAI was compared, none of the parameters analysed [pregnancy and farrowing rates (%), and number of piglets born (total and live)] showed significant differences.

Conclusions

The use of the Dp-CAI technique provides a new AI method as an alternative to CAI and PCAI for pigs. The device, especially designed for gilts, was used with a high degree of success reducing conventional sperm doses without impairing reproductive parameters.

Electronic supplementary material

The online version of this article (10.1186/s40104-019-0313-1) contains supplementary material, which is available to authorized users.

Multi-Farm Analyses Indicate a Novel Boar Pheromone Improves Sow Reproductive Performance

Simple Summary

Pork production farms are more sustainable if the total number of pigs per batch is increased with a given sow herd size. Improving breeding and farrowing rates as well as litter size will increase farm output per sow. This field study examined the effect of application of a novel boar pheromone (BOARBETTER^®; BB) containing three active molecules. Effects on sow reproductive efficiency were measured as breeding and farrowing rates, pigs born alive, stillborn and total numbers born. Farms applied BB in alternating weeks. Among records from nearly 4000 sows enrolled in the study, the use of BB increased the number of pigs born alive per litter and total pigs born per farrowing batch. BOARBETTER^® is a cost effective and safe product that has the potential to meaningfully improve sow reproductive performance.

Abstract

The objective of this study was to examine the effectiveness of a novel 3-molecule boar pheromone (BOARBETTER^®, BB,) to improve sow reproductive performance (breeding, conception, farrowing rates, pigs born alive, stillborn, mummies and total born). Data from 12 commercial farm sites were used to evaluate the effectiveness of BB. Each farm was used as the experimental unit in the meta-analyses. Individual sows records were collected, merged and analyzed in overall analyses. Relative to CON, BB increased the number of total born pigs per litter (13.81 ± 0.11 vs. 14.30 ± 0.11 pigs/litter, respectively; p < 0.01) and the number of pigs born alive (12.76 ± 0.14 vs. 13.13 ± 0.14 pigs/litter, respectively; p < 0.05). In the merged dataset analyses, the parity by treatment interaction was significant for total pigs and pigs born alive per litter (p < 0.01). In parities one through three, treatment with BB increased total pigs born by 0.88 per litter, and pigs born alive per litter by 0.73 pigs per litter (p < 0.05). However, BB had no effect on these parameters in sows from parities four through six. BOARBETTER^® increased reproductive success, is cost effective, safe, and can meaningfully improve sow reproductive success and performance.

Association between antimicrobial usage, biosecurity measures as well as farm performance in German farrow-to-finish farms

Background

Antimicrobial usage in food producing animals is of major concern. A clear link between the extent of use and the development of antimicrobial resistance has already been demonstrated. To evaluate strategies that may reduce the antimicrobial usage while assuring pig health and welfare, it requires profound knowledge of factors that are associated with antimicrobial usage. Data on biosecurity and herd management practices are important parameters to identify risk factors which are related to a higher antimicrobial usage. To investigate between-farm variations of high and low usage the treatment incidence (TI) per age group in 60 German farrow-to-finish herds was qualitatively and quantitatively analysed and linked to biosecurity measures, and herd management characteristics.

Results

Weaned pigs received most of the treatments (median TI = 487.6), followed by suckling pigs (median TI = 138.9). Suckling pigs were treated with critically important antimicrobials (3rd and 4th generation cephalosporines) to a remarkable extent. The number of sows present at site (p < 0.01) and a low score for external biosecurity (p = 0.06) were associated with a higher antimicrobial usage in pigs from birth till slaughter. Herds with a higher treatment incidence in growing pigs (TI 200 days): i) were located in a region with a high pig density (p < 0.01), ii) had a less strict access check for visitors and personnel (p < 0.01) and iii) scored lower in the subcategory ‘cleaning and disinfection’ (internal biosecurity) (p < 0.01). Herds with a higher treatment incidence in breeding pigs weaned more piglets per sow and year and scored better in the internal biosecurity level (p = 0.02).

Conclusions

With the main focus on the treatment incidence in pigs from birth till slaughter and in breeding pigs risk factors for a high usage in these age groups were identified. The level of biosecurity of a herd was associated with the amount of antimicrobials used. Therefore, the findings in this study indicate possible points of action in the reduction and prudent use of antimicrobials in Germany. The active improvement of biosecurity measures could be a promising alternative to reduce antimicrobial usage on herd level.

Electronic supplementary material

The online version of this article (10.1186/s40813-018-0106-5) contains supplementary material, which is available to authorized users.

Salivary and urinary metabolome analysis for pre-puberty-related biomarkers identification in porcine

Estrus synchronization is important for optimal management of gilt reproduction in pig farms. Hormonal treatments, such as synthetic progestogens, are used on a routine basis, but there is a growing demand for non-hormonal alternative breeding tools. Before puberty, gilts exhibit a ‘waiting period,’ related to the ovarian development and gonadotrophin secretions, during which external stimulations, such as boar exposure, could induce and synchronize first ovulation. Practical non-invasive tools for identification of this period in farms are lacking. During this period, urinary oestrone levels are high, but urine sampling is difficult in group-housed females. The aim of this work was to search for specific biomarkers of the ‘waiting period’ in saliva and urine. In total, nine 144- to 147-day-old Large White gilts were subjected to trans-abdominal ultrasonography three times a week for 5 weeks until puberty detection (week –5 to week –1 before puberty). Urine and saliva samples were collected for oestrone assay to detect the ‘waiting period’ and for metabolome analysis using ¹H-nuclear magnetic resonance spectroscopy to detect potential biomarkers of the ‘waiting period.’ Gilts were slaughtered 7 days after puberty detection for puberty confirmation. Results were consistent with ultrasonography data for six gilts. Urine and saliva samples from these six gilts were analyzed. Urinary estrone concentration significantly increased 2 weeks before puberty detection. Metabolome analysis of urine samples allowed the identification of 78 spectral bins, among them, 42 low-molecular-weight metabolites were identified. Metabolome analysis of salivary samples allowed the identification of 59 spectral bins, among them, 23 low-molecular-weight metabolites were detected and 17 were identified. No potential biomarker was identified in urinary samples. In saliva, butyrate and 2HOvalerate, 5.79 ppm (putatively uridine), formate, malonate and propionate could be biomarker candidates to ascertain the pre-puberty period in gilt reproduction. These results confirm that non-invasive salivary samples could allow the identification of the physiological status of the gilts and presumably the optimal time for application of the boar effect. This could contribute to synchronize puberty onset and hence to develop non-hormonal breeding tools.

Monitoring mRNA transcription of genes involved in early pregnancy from endometrium and peripheral blood mononuclear cells of pregnant pigs with different parity

The reproductive success of mammals is largely dependent on the interaction between maternal and foetal interfaces during early pregnancy. Particularly, immune cells which reside at the maternal endometrium can modulate the conception and placental vascularization. In this study, we analysed the transcription of genes involved in early pregnancy from endometrium and peripheral blood mononuclear cells (PBMCs) of pregnant pigs with different parity. Briefly, three groups of female pigs were divided based on parity (0, 2 and 5) and each group was artificially inseminated. Within 30 days of gestation, the total RNA was isolated from the endometrium and PBMCs of sacrificed experimental pigs and the expression patterns of genes involved in early pregnancy were monitored by quantitative real-time RT-PCR. Results indicated absence of correlation between increased parity and the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1-α (HIF-1α) mRNA in endometrium among the groups of pigs analysed. Yet, the mRNA levels of Fas, Fas ligand (FasL) and tumour necrosis factor-α (TNF-α) in the endometrium of parity 5 sows were much higher than those of pregnant gilts (parity 0), and the mRNA ratios of both TNF-α:interleukin-4 (IL-4) and IFN-γ (interferon-γ):interleukin-10 (IL-10) in PBMCs of pregnant pigs were augmented with increasing parity. Furthermore, the mRNA levels of TNF-α and IFN-γ in PBMCs of pregnant pigs were inversely correlated with litter size. These combined results may demonstrate that increased parity of pregnant pigs leads to enhance Th1-prone immunity within the maternal-foetal interface during early pregnancy.

High-performing farms exploit reproductive potential of high and low prolific sows better than low-performing farms

Background

Our objective was to examine the impact of farm effects and sow potential on various aspects of sow performance. We examined the interaction between sow prolificacy groups categorized at parity 1 and farm productivity groups for reproductive performance across parities, and lifetime performance. Data included 419,290 service records of 85,096 sows, on 98 Spanish farms, from first-service as gilts to removal, that were served between 2008 and 2013. Farms were categorized into three productivity groups based on the upper and lower 25th percentiles of the farm means of annualized lifetime piglets weaned per sow over the 6 years: high-performing (HP), intermediate-performing (IP), and low-performing (LP) farms. Also, parity 1 sows were categorized into three groups based on the upper and lower 10th percentiles of piglets born alive (PBA) as follows: 15 piglets or more (H-prolific), 8 to 14 piglets, and 7 piglets or fewer (L-prolific). The farm groups represent farm effects, whereas the sow groups represent sow potential. Linear mixed effects models were performed with factorial arrangements and repeated measures.

Results

Mean parity at removal (4.8 ± 0.01) was not associated with three farm productivity groups (P = 0.43). However, HP farms had 7.7% higher farrowing rates than LP farms (P <  0.05). As a result, H-prolific and L-prolific sows on HP farms had 29.7 and 30.7 fewer non-productive days during lifetime than the respective sows on LP farms (P <  0.05). Furthermore, the H-prolific and L-prolific sows on HP farms had 4.9 and 6.2 more annualized piglets weaned than respective H-prolific and L-prolific sows on LP farms (P <  0.05), which was achieved by giving birth to 0.8–1.0 and 1.4–1.7 more PBA per litter, respectively, than on HP farms during parities 2–6 (P <  0.05). During the first parity, HP farms had 18.8% H-prolific sows compared to 6.2% on LP farms.

Conclusion

Farm effects substantially affected lifetime performance of sows. Higher lifetime productivity of sows on HP farms was achieved by higher farrowing rate, fewer non-productive days, more PBA and more piglets weaned per sow, regardless of prolific category of the sows.

Dietary supplement rich in fiber fed to late gestating sows during transition reduces rate of stillborn piglets

The beneficial effects of dietary fiber (DF) from a behavioral and welfare perspective have been thoroughly studied. However, data on the effects of DF on reproductive performance are scarce. Therefore, the aim of this study was to investigate the impact of increased DF supply during the last 2 wk of gestation on stillbirth rate, preweaning mortality, and total piglet mortality. A total of 644 sows were selected for the experiment from a commercial farm, and the sows were inseminated in weekly batches. Sows in the control group ( = 310) were fed according to the normal feeding strategy of the farm with a gestation diet until 1 wk before expected farrowing, then a transition diet until d 5 of lactation, and then a lactation diet until weaning. Sows in the treatment group ( = 334) were fed as the control group except that 280 g/d of the gestation diet (from d 102 to 108 of gestation) and 570 g/d of the transition diet (from d 109 of gestation until farrowing) was daily replaced with 350 and 700 g/d, respectively, of a DF-rich supplement. Both groups received isocaloric diets on a NE basis. The numbers of live-born and stillborn piglets as well as mortality of live-born piglets with presumed causes of death were recorded. The supplemented DF reduced the proportion of stillborn piglets from 8.8 to 6.6% ( < 0.001) and mortality of total born piglets from 22.3 to 19.9% ( = 0.004) but had no impact on preweaning mortality of the piglets ( = 0.21). Moreover, supplemented DF reduced the proportion of death due to poor viability ( < 0.001; 2.8 vs. 1.5% in the control and treatment groups, respectively) and prevalence of piglet diarrhea ( = 0.004; 0.7 vs. 0.3% in the control and treatment groups, respectively). Crushing, low birth weight, and poor viability were the top 3 contributors to preweaning mortality of live-born piglets, in descending order. In conclusion, the supplemented DF reduced the proportion of stillborn piglets and total piglet mortality as well as mortality due to poor viability and piglet diarrhea in lactation.

PHYSIOLOGY AND ENDOCRINOLOGY SYMPOSIUM: Postnatal reproductive development and the lactocrine hypothesis

Maternal effects on development can program cell fate and dictate offspring phenotype. Such effects do not end at birth, but extend into postnatal life through signals communicated from mother to offspring in first milk (colostrum). Transmission of bioactive factors from mother to offspring as a specific consequence of nursing defines a lactocrine mechanism. The female reproductive tract is not fully formed at birth (postnatal day = PND 0). Data for ungulates and mice indicate that disruption of development during neonatal life can have lasting effects on the form and function of uterine tissues. Uterine growth and histogenesis proceed in an ovary-independent manner shortly after birth, suggesting that extra-ovarian inputs are important in this process. Data for the pig indicate that lactocrine signals communicated within 12 to 48 h from birth constitute one source of such uterotrophic support. Disruption of lactocrine signaling, either naturally, by limited colostrum consumption, or experimentally, by milk replacer feeding, alters neonatal porcine uterine development and can have negative consequences for reproductive performance in adults. Substantial differences in endometrial and uterine gene expression between colostrum- and replacer-fed gilts were evident by PND 2, when RNA sequencing revealed over 800 differentially expressed, lactocrine-sensitive genes. Lactocrine-sensitive biological processes identified through transcriptomic studies and integrated microRNA-mRNA pathway analyses included those associated with both cell-cell and ESR1 signaling, and tissue development. Evidence for the pig indicates that colostrum consumption and lactocrine signaling are required to establish a normal uterine developmental program and optimal uterine developmental trajectory.

Cluster analysis reveals seasonal variation of sperm subpopulations in extended boar semen

This study aimed to identify motile sperm subpopulations in extended boar semen and to observe the presumptive seasonal variation in their distribution. Data from 4837 boar ejaculates collected over a two-year period were analyzed in terms of kinematic parameters by Computer Assisted Sperm Analysis (CASA). Individual sperm data were used to determine subgroups of motile sperm within the ejaculates using cluster analysis. Four motile sperm subpopulations (SP) were identified, with distinct movement patterns: SP1 sperm with high velocity and high linearity; SP2 sperm with high velocity but low linearity; SP3 sperm with low velocity but high linearity; and SP4 sperm with low velocity and low linearity. SP1 constituted the least overall proportion within the ejaculates (P < 0.05). Season of semen collection significantly influenced the different proportions of sperm subpopulations. Spring was characterized by similar proportions of SP1 and SP4 (NS) and higher proportions of SP3. Summer brought a decrease in both subgroups containing fast sperm (SP1 and SP2) (P < 0.05). During autumn, increases in SP2 and SP4 were recorded. Winter substantially affected the proportions of all sperm subpopulations (P < 0.05) and SP2 became the most represented subgroup, while SP1 (fast and linear) reached its highest proportion compared to other seasons. In conclusion, extended boar semen is structured in distinct motile sperm subpopulations whose proportions vary according to the season of collection. Summer and autumn seem to have a negative impact on the fast and linear subpopulation. Cluster analysis can be useful in revealing differences in semen quality that are not normally detected by classical evaluation based on mean values.

Maternal lactocrine programming of porcine reproductive tract development

The lactocrine hypothesis for maternal programming of female reproductive tract development is based on the idea that non-nutritive, milk-borne bioactive factors (MbFs), delivered from mother to offspring during nursing, play a role in determining the trajectory of development with long-term consequences in the adult. Porcine female reproductive tract development is completed postnatally, and the period during which maternal support of neonatal growth derives exclusively from colostrum/milk defines a window of opportunity for lactocrine programming of reproductive tissues. Beyond nutrition, milk serves as a delivery system for a variety of bioactive factors. Porcine relaxin is a prototypical MbF. Present in colostrum at highest concentrations at birth, relaxin is transmitted into the circulation of nursing piglets where it can act on Relaxin receptors found in neonatal female reproductive tract tissues. This process is facilitated by the physiology of the maternal-neonatal dyad and the fact that the neonatal gastrointestinal tract is open to absorb macromolecules for a period of time postnatally. Age at first nursing and duration of nursing from birth are also important for porcine female reproductive tract development. These parameters affect both the quality and quantity of colostrum consumed. Disruption of lactocrine signaling by feeding milk replacer from birth altered porcine uterine, cervical, and testicular development by postnatal Day 2. Moreover, insufficient colostrum consumption in nursing piglets can impair uterine capacity to support viable litters of optimal size in adulthood. In the pig, lactocrine signaling supports neonatal organizational events associated with normal reproductive development and may program adult uterine capacity.

Fetal and neonatal programming of postnatal growth and feed efficiency in swine

Maternal undernutrition or overnutrition during pregnancy alters organ structure, impairs prenatal and neonatal growth and development, and reduces feed efficiency for lean tissue gains in pigs. These adverse effects may be carried over to the next generation or beyond. This phenomenon of the transgenerational impacts is known as fetal programming, which is mediated by stable and heritable alterations of gene expression through covalent modifications of DNA and histones without changes in DNA sequences (namely, epigenetics). The mechanisms responsible for the epigenetic regulation of protein expression and functions include chromatin remodeling; DNA methylation (occurring at the 5´-position of cytosine residues within CpG dinucleotides); and histone modifications (acetylation, methylation, phosphorylation, and ubiquitination). Like maternal malnutrition, undernutrition during the neonatal period also reduces growth performance and feed efficiency (weight gain:feed intake; also known as weight-gain efficiency) in postweaning pigs by 5-10%, thereby increasing the days necessary to reach the market body-weight. Supplementing functional amino acids (e.g., arginine and glutamine) and vitamins (e.g., folate) play a key role in activating the mammalian target of rapamycin signaling and regulating the provision of methyl donors for DNA and protein methylation. Therefore, these nutrients are beneficial for the dietary treatment of metabolic disorders in offspring with intrauterine growth restriction or neonatal malnutrition. The mechanism-based strategies hold great promise for the improvement of the efficiency of pork production and the sustainability of the global swine industry.

Effect of timing of relocation of replacement gilts from group pens to individual stalls before breeding on fertility and well-being

Variation in gilt fertility is associated with increased replacement and reduced longevity. Stress before breeding is hypothesized to be involved in reduced fertility. This study tested the timing of gilt relocation from pens to individual stalls before breeding on fertility and well-being. The experiment was performed in replicates on a commercial research farm. After detection of first estrus, gilts ( = 563) were assigned to treatment for relocation into stalls 3 wk (REL3wk), 2 wk (REL2wk), or 1 wk (REL1wk) before breeding at second estrus. Subsets of gilts from each treatment ( = 60) were selected for assessment of follicles at second estrus. Data included interestrus interval, number of services, conception, farrowing, total born, and wean to service interval. Piglet birth weight was obtained on subsets of litters ( = 42/treatment). Measures of well-being included BW, backfat, BCS, lesions, and lameness from wk 1 after first estrus until wk 16. Gilt BW at wk 5 (158.4 kg) was not affected ( > 0.10) by treatment. Measures of BCS, lameness, and lesions at breeding and throughout gestation did not differ ( > 0.10). Treatment did not affect ( > 0.10) gilts expressing a normal interestrus interval of 18 to 24 d (83.4%) but did influence ( < 0.05) the proportion expressing shorter ( < 0.001) and longer ( < 0.001) intervals. Gilts in REL3wk had a shorter ( < 0.001) interestrus interval (20.7 d) than those in REL2wk and REL1wk (22.6 d). Gilts with shorter intervals ( = 24) had fewer total born while gilts expressing longer cycles ( = 65) had reduced farrowing rates. The number of services (1.9) and number of follicles (19.7) at breeding were not affected ( > 0.10) by relocation. There was no effect of treatment on farrowing rate (85.2%), born alive (12.6), or any litter birth weight measures ( > 0.10). The percentage of sows bred within 7 d after weaning (94.4%) was also not affected by treatment ( > 0.10). These results suggest that the timing of relocation before breeding had no effect on well-being or on the majority of gilts with normal estrous cycles and their subsequent fertility. However, a smaller proportion of the gilts exhibited shorter and longer interestrus intervals in response to relocation 1 or 3 wk before breeding. In cases where gilt fertility may be less than optimal, producers that relocate gilts from pens to stalls before breeding should evaluate interestrus interval as a response criterion.

Exposure to the Contraceptive Progestin, Gestodene, Alters Reproductive Behavior, Arrests Egg Deposition, and Masculinizes Development in the Fathead Minnow (Pimephales promelas)

Endogenous progestogens and pharmaceutical progestins enter the environment through wastewater treatment plant effluent and agricultural field runoff. Lab studies demonstrate strong, negative exposure effects of these chemicals on aquatic vertebrate reproduction. Behavior can be a sensitive, early indicator of exposure to environmental contaminants associated with altered reproduction yet is rarely examined in ecotoxicology studies. Gestodene is a human contraceptive progestin and a potent activator of fish androgen receptors. Our objective was to test the effects of gestodene on reproductive behavior and associated egg deposition in the fathead minnow. After only 1 day, males exposed to ng/L of gestodene were more aggressive and less interested in courtship and mating, and exposed females displayed less female courtship behavior. Interestingly, 25% of the gestodene tanks contained a female that drove the male out of the breeding tile and displayed male-typical courtship behaviors toward the other female. Gestodene decreased or arrested egg deposition with no observed gonadal histopathology. Together, these results suggest that effects on egg deposition are primarily due to altered reproductive behavior. The mechanisms by which gestodene disrupts behavior are unknown. Nonetheless, the rapid and profound alterations of the reproductive biology of gestodene-exposed fish suggest that wild populations could be similarly affected.

Evaluation of the relationship between the biosecurity status, production parameters, herd characteristics and antimicrobial usage in farrow-to-finish pig production in four EU countries

BACKGROUND

High antimicrobial usage and the threat of antimicrobial resistance highlighted the need for reduced antimicrobial usage in pig production. Prevention of disease however, is necessary to obtain a reduced need for antimicrobial treatment. This study aimed at assessing possible associations between the biosecurity level, antimicrobial usage and farm and production characteristics in order to advice on best practices for a low antimicrobial usage and maximum animal health and production. A cross-sectional study was conducted in 227 farrow-to-finish pig herds in Belgium, France, Germany and Sweden between December 2012 and December 2013. Associations between biosecurity status, antimicrobial usage, and production parameters were evaluated with multivariable general linear models, according to an assumed causal pathway.

RESULTS

The results showed that higher antimicrobial usage in sows tended to be associated with higher antimicrobial usage from birth until slaughter (p = 0.06). The antimicrobial usage from birth until slaughter was positively associated with the number of pathogens vaccinated against (p < 0.01). A shorter farrowing rhythm (p < 0.01) and a younger weaning age (p = 0.06) tended to be also associated with a higher antimicrobial usage from birth until slaughter whereas a better external biosecurity (p < 0.01) was related with a lower antimicrobial usage from birth until slaughter.

CONCLUSION

Management practices such as weaning age and biosecurity measures may be important factors indirectly impacting on antimicrobial usage. We therefore promote a holistic approach when assessing the potential to reduce the need for antimicrobial treatments.