Reproductive Performance Of Gilts Research Articles

10 Effects of different feeding levels during gestation on gilt reproductive performance during the first lactation

Abstract Our objective was to determine the effects of different feeding levels for gilts during gestation on reproductive performance during the first lactation. A total of 1,187 PIC Camborough gilts were used. Gilts were randomly allotted in a randomized complete block design based on breeding week, body weight (BW), and age to one of four treatments differing in daily metabolizable energy (ME) intakes per day during gestation. Gilts were housed in stalls throughout the entire gestation and individually fed with a gestation diet containing 2.95 Mcal of ME/kg via feed boxes that were weekly calibrated. Treatments consisted of 1) 5.0 Mcal of ME/d (1.7 kg feed/d) throughout the entire gestation; 2) 5.9 Mcal of ME/d (2.0 kg feed/d) throughout the entire gestation; 3) 6.8 Mcal of ME/d (2.3 kg feed/d) throughout the entire gestation; and 4) 5.0 Mcal of ME/d (1.7 kg feed/d) from breeding until d 90 of gestation, and then 5.9 Mcal of ME/d (2.0 kg feed/d) from d 90 to d 112 of gestation. Gilt was the experimental unit and data were analyzed using generalized linear mixed models with the lmer and glmer functions of R. There was no evidence (P > 0.10) for treatment differences on gilt BW and age at breeding, with gilts averaging 156.7 kg at 210 d of age (Table 1). Gilts receiving 6.8 Mcal of ME/d during gestation were heavier (P < 0.05) at farrowing compared with all other treatments; however, these gilts lost (P < 0.05) more BW during lactation. Gilts receiving 5.0 Mcal ME/d throughout the entire gestation had less (P < 0.05) maternal net BW gain from breeding to weaning compared with gilts receiving 6.8 Mcal ME/d. Gilts receiving 6.8 Mcal of ME/d gained more (P < 0.05) caliper scores (CS) from breeding to d 90 of gestation compared with gilts receiving 5.0 Mcal ME/d. Regardless of feeding level, gilts lost an average of 0.85 CS from d 90 to d 112 of gestation. Overall, gilts receiving 6.8 Mcal of ME/d gained more CS during gestation, but lost more CS during lactation (P < 0.05). There was no evidence for differences in gilt backfat depth measurements (P > 0.10). Gilt feeding levels did not impact (P > 0.10) total piglets born, percentage sillborn, or percentage of mummified fetuses. Gilts receiving 5.0 Mcal of ME/d had greater (P < 0.05) percentage piglets born alive compared with gilts receiving 5.9 Mcal of ME/d, with other treatments intermediate. There was no evidence (P > 0.10) for treatment differences in average piglet BW, average piglet daily gain during lactation, piglet mortality from cross foster to weaning, or wean to estrus interval in the next cycle. In summary, increasing energy intake of gilts during the first gestation did not impact reproductive performance during the first lactation, but gilts receiving 5.0 Mcal of ME/d throughout the entire gestation had less maternal net BW gain.

83 Effect of stocking density on F1 gilt reproductive performance

Abstract Replacement females are the future of a farm, and their development can impact production. Currently, replacement gilts are housed in many different environments. Stocking density of replacement females is one factor that varies across production systems. Therefore, the objective of this study was to evaluate the effect of different stocking densities on replacement gilt reproductive performance. At 10 wk of age, DNA L241 females (n = 824; DNA Genetics, Columbus, NE) were randomly allotted to finishing pens with 3 different stocking densities. Each stocking density consisted of 12 pens of 0.71 m2 (n = 360), 0.93 m2 (n = 264), and 1.25 m2 (n = 204). Heat detection started at 20 wk of age with fence line exposure for 2 wk at 15 minutes per pen. Within pen boar exposure occurred from 22 to 31 wk of age for a minimum of 10 min per pen. Starting at 20 wk of age, females that exhibited red and swollen vulvas or standing estrus were recorded. Body weight, backfat, and loin depth measurements were collected at estrus detection. A blood progesterone assay was performed on all females at 24 wk of age. Further blood progesterone assays were performed at 27, 29 and 31 wk of age on any female for which progesterone was not detected on previous assays. Females were mated on their 2nd estrus if they were at least 136 kg or on their first estrus if they were over 145 kg. Body weight was recorded at the time of mating. For females that cycled by 31 wk, females in the 0.71 m2 treatment cycled significantly earlier than the 0.93 m2 treatment, 147 vs 153 d post-weaning respectively (P < 0.05). No difference was detected in age at mating; however, gilts in the 0.71 m2 treatment were 5.9 kg and 8.2 kg lighter than the 0.93 and 1.25 m2 treatments respectively (P < 0.01). At 31 wk of age 60% of the 0.71 m2, 71% of the 0.93 m2, and 77% of the 1.25 m2 treatments had cycled according to visual heat detection. However, according to the progesterone assay, at 31 wk of age 75% of 0.71 m2, 81% of the 0.93 m2, and 84% of the 1.25 m2 had cycled. The accuracy of visual heat detection compared with progesterone assay were 79.4% for 0.71 m2, 77.3% for 0.93 m2, and 85.8% for 1.25 m2 treatments. Overall, the 1.25 m2 treatment resulted in heavier females at mating, a greater rate of females cycling, and a more accurate detection of females cycling than the 0.71 m2 treatment. Swine producers can improve the percentage of females detected in estrus and mated in the desired period by providing additional rearing space during gilt development.

Enhancement of selectivity, 25-hydroxyvitamin D3 level, alkaline phosphatase activity and reproductive performance in gilts and primiparous sows using 14-epimer of 25-hydroxyvitamin D3

Selecting breed-worthy gilts as sow replacements is essential for continuity of pig production cycle. Though vitamin D3 (VD3) is known to enhance reproductive performance of multiparous sows, there is still a knowledge gap on its impact in developing gilts and primiparous sows. This study was aimed to quantify plasma 25-hydroxyvitamin D3 (25(OH)D3), serum alkaline phosphatase (ALP), and examine the reproductive performance of primiparous sows fed diets supplemented with regular VD3, and its 25(OH)D3 epimers. The study sample comprised 10-week-old replacement gilts (50 % Landrace x 50 % Yorkshire, N = 180) assigned in a randomized complete block design to three treatments [2,000 IU/kg of VD3 (T1), 25 µg/kg of 14‑epi-25(OH)D3, half dose (T2), and 50 µg/kg of 25(OH)D3 (T3)] equilibrated to 2,000 IU/kg in base diets. Selections occurred at 22, 27 and 35 weeks of age, respectively. Plasma 25(OH)D3, serum alkaline phosphatase (ALP), bone structure and reproductive performance were analyzed. Dietary treatments influenced carpus (P = 0.023), fore view stance (P = 0.017), infantile vulva (P = 0.014), inverted (P = 0.048), and prominent teat (P < 0.001). Post-partum 25(OH)D3 concentration and ALP activity were elevated by day 25 (P < 0.001). Treatment diets also influenced total born (P < 0.001), born alive (P = 0.048), and still born (P = 0.049). Two factors affect circulating 25(OH)D3 and ALP activity: physiological changes in sows during lactation, and dietary 25(OH)D3 intake. 14‑epi-25(OH)D3 is a potent metabolite for improving maturation of reproductive organs in developing gilts. It also reduces still birth in primiparous sows.

Reproductive performance in gilts submitted to non-steroidal therapies to prolong the luteal phase of the estrous cycle

Synchronized cyclicity of replacement gilts is crucial to optimize breeding herd management, however, protocols with oral progestogen are expensive and require daily administration. This study tested two synchronization protocols without progestogens during the luteal phase in gilts. In Experiment I, on the day of the expression of the third estrus (D0), gilts were assigned to three groups (n = 6, each): control, with no treatment; PGF25: in which gilts received two doses of hCG (1,500 IU each) on D12 and D15 and two doses of a prostaglandin F2α (PGF) analogue (sodium cloprostenol; 250 µg) 6-h apart, on D25; and PGF30: in which gilts received two doses of hCG (1,500 IU each) on D12 and D15 and two doses of the PGF analogue (sodium cloprostenol; 250 µg) 6-h apart, on D30. The interval between PGF treatment and estrus expression was shorter in PGF30 than in PGF25 (P < 0.01). The PGF treatment failed to decrease serum progesterone (P4) for gilts from the PGF25 group (P > 0.05), but it was effective for gilts in the PGF30 group (P = 0.01). In Experiment II, gilts were assigned to three groups (n = 12, each): control (no treatment); eCG+hCG (400 IU eCG on D10 plus 500 IU hCG on D12); and hCG2 (two hCG doses, 1,500 IU each on D12 and D15). On D30, gilts from eCG+hCG and hCG2 that did not express estrus received two doses of the PGF analogue (250 µg each, 6-h apart). All gilts were inseminated when estrus was detected. Serum P4 concentrations were similar for all groups on D10 (P > 0.05) and greater on D20 and D25 for gilts in eCG+hCG and hCG2 (P < 0.01) than for those in the control, whereas P4 concentration was greater in hCG2 than in eCG+hCG, on both moments. The inter-estrus interval (IEI) was shorter for control gilts and intermediate for gilts in eCG+hCG, while the longest IEI was observed for gilts in hCG2 (P < 0.01). Total litter size was larger for gilts in the control (P = 0.02) compared to those in hCG2 and did not differ from the other groups for gilts in eCG+hCG (P > 0.05). In conclusion, Experiment I showed that PGF treatment did not induce luteolysis 10 days after the second hCG treatment but it was effective 15 days after the second hCG application. Additionally, Experiment II showed that both eCG+hCG and hCG2 were efficient in prolonging the luteal phase; however, number of piglets born alive and total litter size were negatively affected by the hCG2 protocol. In this sense, treatment with eCG+hCG or hCG2 may represent a steroid-free approach to prolong the luteal phase in gilts, although the doses and number of treatments must be further investigated.

Effect of yeast extracted β-glucans on the immune response and reproductive performance of gilts in the adaptation, gestation, and lactation periods

Yeast β-glucans may have beneficial effects on the immune response of gilts and their litter through immunomodulation from the gastrointestinal tract. Thus, the objective of this study was to evaluate the effect of the inclusion of β-glucans in the diet of replacement gilts during the adaptation, gestation and lactation phases on their response and the response of their litter to vaccines against Parvovirus and Leptospirosis, as well as its effect on parity performance and immune parameters of colostrum and milk. In two trials, gilts were randomly assigned to one of two treatments: with or without the inclusion of β-glucans at 300 g/ton in the basal diet. Gilts consumed the experimental diets during the adaptation period in the first experiment (EXP1) and from d 75 of gestation until d 10 of lactation in the second experiment (EXP2). Blood samples were collected from sows and from their piglets. In addition to blood collections, colostrum and milk were also collected in EXP2, and the reproductive performance of sows at the first farrowing was evaluated. Qualitative data were analyzed by chi-square, and quantitative data were evaluated using ANOVA or Kruskal-Wallis, according to their normality. There was an effect of treatment in EXP2 on the IgA and IgM concentrations and mitogenic activity in colostrum (P < 0.05), and for IgA in milk from sows (P < 0.05). For parvovirus and Leptospira spp. antibodies, in the two experiments, there was no difference between treatments (P > 0.05), as well as for reproductive parameters. Thus, under the experimental conditions of this study, it is possible to conclude that including 300 g/ton β -glucans in the diet of first-parity sows can increase the concentration of IgA in their colostrum and milk, as well as the proliferation of intestinal epithelial cells, while decreasing the concentration of IgM in their colostrum, but not in milk.

Gilt reproductive performance in a tropical environment after oestrus synchronization and fixed-time artificial insemination

The present study was performed to evaluate the reproductive performance of gilts inseminated using fixed-time artificial insemination (FTAI) protocol. A total of 408 Landrace × Yorkshire crossbred gilts were included in the experiment. Gilts at 8 months of age were randomly allocated into three groups: control AI (n = 192), treatment 1–TAI (n = 117) and treatment 2–FTAI (n = 99). Gilts in the control AI group were inseminated 2–3 times during standing oestrus at 0, 12 and 24 h after the onset of oestrus. Gilts in the treatment 1–TAI group were orally administered 20 mg per day of altrenogest for 18 days and then inseminated 2–3 times during standing oestrus by conventional AI. Gilts in the treatment 2–FTAI group were synchronized like gilts in treatment 1–TAI group but then GnRH (10 μg of buserelin) was administered 120 h after the end of altrenogest treatment and fixed time artificial inseminated twice at 24 and 32 h after GnRH irrespective of the presence of oestrus or not. Conception rate of gilts in treatment 2–FTAI (87.9%) was similar to the treatment 1–TAI (94.9%) and control AI (83.3%) (P > 0.05). Conception rate in treatment 1–TAI (94.9%) was higher compared to control AI group (83.3%, P = 0.040). Farrowing rate of gilts in treatment 2–FTAI (83.8%) was similar to treatment 1–TAI (89.7%) and control AI (76.0%) (P > 0.05). Farrowing rate of treatment 1–TAI (89.7%) was higher than control AI gilts (76.0%, P = 0.033). In treatment 2–FTAI, the conception and farrowing rate of the nine gilts that were inseminated even if they were not detected in oestrus (all during warm season) was 44.4% and 44.4%, respectively. Regular return to oestrus was similar between groups (9.4%, 0.9% and 4.1% for control AI, treatment 1–TAI and treatment 2–FTAI, respectively, P > 0.05). The total number of piglets born per litter in treatment 1–TAI group was higher than control AI (13.1 ± 0.2 versus 11.6 ± 0.2, respectively, P < 0.001) and treatment 2–FTAI groups (12.2 ± 0.3, P = 0.019). The number of piglets born alive was higher in treatment 1–TAI (12.1 ± 0.3) compared to treatment 2–FTAI (11.3 ± 0.2) and control AI group (11.2 ± 0.3). The percentage of stillbirth and mummified foetus were not different between groups (P > 0.05). The present study indicated that fixed-time AI in gilts can be successfully performed by administration of altrenogest for 18 days, GnRH at 120 h after altrenogest withdrawal and then double fixed-time AI at 24 and 32 h after the administration of GnRH. Fertility metrics such as conception rate, farrowing rate and litter performances using this method were similar to gilts inseminated at oestrus with conventional AI.

Effects of age at first breeding and dietary energy levels during the rearing period of replacement gilts on reproductive performance

Context The occurrence of second parity syndrome is a major reason for culling sows depending on the bodyweight and energy level balance during the first lactation. Equally, the nutrition of gilts during the rearing period influences the age of first oestrus, longevity and reproductive performance. Aims The experiment investigated: (1) the influence of gilt mating age (early [EL], middle [MD] and late [LT]) at the first parity on reproductive performance, and (2) the interaction between dietary energy levels (high, 3320 kcal/kg; low, 3120 kcal/kg) and mating age. Methods A total of 120 crossbred (Duroc × Landrace × Yorkshire) gilts were allotted to six treatments according to a 3 × 2 factorial arrangement based on mating age (EL [222 days], MD [244 days] and LT [264 days]) at the first parity and dietary energy levels (high, 3320 kcal/kg; low, 3120 kcal/kg). The average weight of gilts were 141 ± 3, 153 ± 3 and 164 ± 3 for the EL, MD and LT groups, respectively. Results High-energy diets tended to increase the growth rate of gilts (P = 0.083). At insemination, bodyweight and back-fat thickness were higher (P &lt; 0.05) in the LT group. Back-fat thickness at farrowing was lower (P &lt; 0.05) in the EL group. The back-fat thickness loss during lactation was highest in the LT group (P &lt; 0.05) during parity one and two. Feed intake during lactation was significantly reduced (P &lt; 0.05) in the LT gilts in parity one. Insemination age and dietary energy levels had no significant effects on, litter size, litter weight and weaning to oestrus interval. A higher blood insulin-like growth factor (P &lt; 0.05) was observed in the EL gilts during the first service and weaning. Conclusion Based on these findings, early inseminated gilts had a lower bodyweight loss during lactation without affecting litter size or growth, which in the long term may positively impact culling age. Implication This information may guide swine farmers on the most appropriate age to breed gilts at first service for increased reproductive life. The provision of high-energy feeds did not translate into any meaningful interaction towards improving reproductive performance in gilts.

Utilization and reproductive performance of gilts in large-scale pig farming system with different production levels in China: a descriptive study

BackgroundThis study was to investigate the utilization and reproductive performance of gilts in large-scale pig farms. Data of this descriptive study included 169,013 gilts of 1540 gilts’ batches on 105 large-scale pig farms from April 2020 to March 2021. According to the upper and lower 25th percentiles of piglets weaned per sow per year (PSY) during the research stage, pig farms were divided into three productivity groups: high-performing (HP), intermediate-performing (IP) and low-performing (LP) farms. On the basis of breeds, LP (LP-Total) farms was further divided into LP-breeding pig (LP-BP) and LP-commercial pig (LP-CP) groups. Average utilization, estrus and first mating data was collected from a total of 1540 gilts’ batches. The age-related factors (introduction age, age at first estrus and age at first mating) and litter production (total number of piglets, number of piglets born alive and number of weaned piglets, as well as their proportion distribution) among HP and LP groups were compared. The litter production in different age groups were also analyzed.ResultsThe introduction age, mortality and culling rate of HP farms were lower compared with LP farms. Total number of piglets per litter, number of piglets born alive per litter and number of weaned piglets per litter in HP farms were significantly more than those of LP groups, respectively. The proportion distribution peaks of litter production in HP farms were shifted about two more than those in LP groups, respectively; and the proportion of low litter production (eight per litter or less) was lower than that in LP groups. The results of different age groups showed that total number of piglets per litter and number of piglets born alive per litter in 220–279 d were the most, while that of 370 d was the least.ConclusionsThe overall utilization and reproductive performance of gilts in HP farms was better than those of LP farms. The difference in utilization was reflected in introduction source, culling rate and mortality. While the age at first estrus and first mating, breeds and litter production were the main differences for reproductive performance.

Vaginal bacterial diversity from healthy gilts and pregnant sows subjected to natural mating or artificial insemination.

The profitability of commercial pig farms largely depends on the reproductive performance of gilts and sows. The aim of this study was to identify differences in the composition and diversity of vaginal microbiota between gilts (G) and pregnant (P) sows, both artificially inseminated (AI) and natural mating (NM). Samples were collected by scraping the vaginal mucosa of G (n = 10) and P (NM, n = 10 and AI, n = 7) sows. Samples were analysed by culture-dependent techniques and 16S-rRNA gene High-Throughput-Sequencing. The profiles of the cultured microbiota showed two distinctive clusters, one of them grouped four samples of P sows from the AI group. The vaginal microbiota from P had lower richness than G sows (Mann-Whitney/Kruskal-Wallis test, p < 0.01), but all vaginal samples had a similar diversity. The PERMANOVA analyses revealed significant differences (p < 0.01) between the microbial communities' structures from G and P sows. The bacteria phyla with the highest relative abundances were Proteobacteria (33.1%), followed by Firmicutes (32%), Cyanobacteria (13.3%) and Actinobacteria (13.2%). The relative abundance for phyla, families and genera was estimated and Proteobacteria was significantly higher (p = 0.038) in P than in G sows; Firmicutes was significantly lower in AI than G and NM sows. A “core microbiota” included Lactobacillus, Bacillus, Enterococcus, Acinetobacter and Pseudomonas. The results presented highlight the differences in the bacterial composition between G and P sows, as well as the changes in the microbial populations associated with the breeding method.

Effects of increasing standardized ileal digestible lysine during gestation on reproductive performance of gilts and sows

Limited information is available on lysine requirement estimates of modern, high-producing gestating sows Therefore, the objective of this study was to evaluate the effects of increasing standardized ileal digestible (SID) lysine during gestation on piglet birthweight and reproductive performance of gilts and sows. A total of 936 females (498 gilts, 438 sows; Camborough®, PIC, Hendersonville, TN) were group-housed (approximately 275 females per pen) and individually fed with electronic sow feeders. Females were moved from the breeding stall to pens on d 4 of gestation and allotted to one of four dietary treatments on d 5. Dietary treatments included increasing SID lysine intake (11.0, 13.5, 16.0, and 18.5 g/d). Gilts (parity 1) and sows (parity 2+) received 2.1 and 2.3 kg (22.2 and 24.3 MJ net energy per day) of feed throughout the entire gestation period, respectively. Dietary treatments were achieved by different blends of low (0.48% SID lysine) and high (0.88% SID lysine) lysine diets, prepared by changing the amount of corn and soybean meal in these two diets. Female weight and backfat were recorded on d 4 and 111 of gestation. Individual piglet weight was obtained within 12 h of birth on litters from 895 females. Final weight, and calculated maternal BW, body lipid, and body lean at d 111 of gestation increased (linear, P < 0.01) for gilts and sows as SID lysine increased. There was no evidence for differences in final backfat depth. Average total born for gilts and sows was 15.3 and 16.0 pigs with no evidence for differences among treatments. The percentage of pigs born alive increased (P = 0.01) with increasing SID lysine intake for sows, but not in gilts as a result of a treatment by parity group interaction (P = 0.04) for percentage of stillborn pigs. Increasing SID lysine intake during gestation did not affect the percentage of mummified fetuses, total born, or birthweight of piglets born alive in this study. In addition, increasing SID lysine intake during gestation did not affect subsequent reproductive performance. In conclusion, increasing dietary SID lysine intake in gestation increased female BW, without changing backfat depth. The minimal effects on female reproductive performance and piglet birthweight suggest that 11 g/day of SID lysine intake appears to be adequate for gestating gilts and sows; however, providing sows with 18.5 g/d SID lysine reduced (P = 0.01) stillbirth rate by 2.3 percentage points.

Influence of Backfat Thickness and the Interval from Altrenogest Withdrawal to Estrus on Reproductive Performance of Gilts.

Simple SummaryAltrenogest, also known as allyl trenbolone, is a steroidal progestin that is widely used in veterinary medicine to synchronize estrus in gilts. To achieve the target number of services per week, enough weaned sows and gilts are needed each week for breeding. A problem with progestogen-synchronized replacement gilts is the variation of the interval between last feeding of altrenogest and onset of estrus. In the present study, we found that gilt backfat thickness had a strong positive correlation with the interval between last feeding of altrenogest and onset of estrus. This result may come from a larger reservoir of altrenogest in adipose tissue in fatter gilts.Estrus synchronization of gilts can be achieved by feeding the orally active progestogen altrenogest (AT) to cycling gilts at 20 mg/day for 14 to 18 days with gilts usually returning to estrus 4 to 8 days after the last feeding. In practice, gilts failing to exhibit estrus by 6 days after AT withdrawal may compromise weekly breeding targets. The cause of prolonged intervals to estrus are unknown but may involve prolonged suppression due to the release of progesterone (P4), and by extension AT, from adipose tissues. The present study examined relationships between gilt P2 backfat depth (<13.5 mm, 14–16.5 mm, >17 mm groups), the AT withdrawal to estrus interval, and subsequent reproductive performance in gilts. We noted longer intervals to estrus in gilts with greater P2 backfat depths (p < 0.0001), and higher serum P4 concentrations on the last day of AT feeding and at estrus detection (p < 0.05). Total born litter sizes were unaffected by backfat depth, but pigs born alive progressively decreased with increasing backfat depth with the fattest gilts producing the fewest liveborn pigs (p < 0.05). Taken together, these data suggest that adipose tissues may provide a reservoir of steroid, with its release from fatter gilts having potential negative effects on their subsequent reproductive performance.

Behavior and gilts reproductive performance kept in different breeding systems

The search for improving the quality of life has been studied through the use of management and facilities that can improve the welfare of farm animals. The objective of this work was to evaluate the influence of different housing systems during the gestation and maternity phases on the behavior and performance of gilts. The animals were distributed in a completely randomized design, with two treatments and four replications, with the gilt being considered the experimental unit. The treatments were: Group 1 - Caged confinement system; Group 2 - Picket and stall breeding system. Data on behavior and reproductive performance of gilts and productive performance of piglets were collected. The gilts in the gestation phase housed in the confinement cages, remained mostly inactive at the three collection times (8:00 – 10:00, 12:00 – 14:00 and 16:00 – 18:00) and shorter alert time between 8:00 – 10:00 and 12:00 – 14:00, compared to gilts reared in paddocks. Animals housed in paddocks remained on alert 87.3% above the observation time compared to females housed in individual cages. Females raised in paddocks had a higher (P &lt; 0.05) number of piglets born alive. All indexes evaluated in piglets did not show differences (P &gt; 0.05) between housing systems. The paddock system during pregnancy provided an improvement in the welfare of the gilts, but it was not enough to improve the reproductive and piglet performance in the maternity.

Reproductive performance in gilts following applications of different insemination doses and techniques

This study evaluated the applicability of intrauterine artificial insemination (IUAI) in gilts and the impact of age at insemination and different body characteristics of gilts on the success rate for cannula insertion. Additionally, reproductive performance was evaluated for IUAI and cervical artificial insemination (CAI), considering different semen dose sizes. A total of 636 gilts were assigned in a 2 × 2 factorial design: two artificial insemination techniques (CAI and IUAI) and two semen dose sizes (1.5 × 109 sperm cells/50 mL or 2.5 × 109 sperm cells/80 mL). In those gilts assigned to IUAI (n = 319) the success rate for intrauterine cannula insertion was evaluated according to weight at first detected estrus, body condition score (BCS), and age at insemination. Reproductive performance, occurrence of bleeding, and semen backflow during all inseminations were compared among groups (2 × 2). Two subgroups were evaluated regarding the time expended to perform insemination (n = 380), and the semen backflow collected during 1 h after insemination (n = 114). The success rate for intrauterine cannula insertion, based on a successful insertion in all inseminations performed during estrus, was 58.9%. Additionally, greater possibility (>60%; P ≤ 0.04) of cannula insertion was observed in heavier gilts (≥124 kg), as well as in older gilts (≥225 d) and those with greater BCS (>3). There were no differences among the groups in pregnancy rate (≥95.3%; P = 0.23), farrowing rate (≥93.7%; P = 0.54), total piglets born (≥14.5; P = 0.45), as well as, bleeding (P = 0.48) and backflow (P = 0.48) during insemination. However, the percentage of semen backflow volume and percentage of sperm cells in the backflow were lower in gilts inseminated by CAI with 1.5 billion sperm cells/50 mL (P < 0.01) than in the other groups. There was no expressive reduction in time expended to perform IUAI compared to CAI. However, gilts inseminated with 1.5 billion sperm cells/50 mL showed a lower total time to inseminate than all other groups (P < 0.01). In conclusion, higher weight, BCS, and age increased the success rate for cannula insertion. However, IUAI did not optimize the insemination procedure, and remains limited for gilts due to the low success rate for cannula insertion. Reproductive performance was not affected by IUAI or CAI using 1.5 or 2.5 billion sperm cells in 50 or 80 mL, respectively, suggesting the possibility of using CAI with 1.5 billion sperm cells/50 mL in gilts.

Evaluation of on-farm indicators of gilt reproductive performance potential at 21 days of age.

Selection of replacements for the sow herd is one of the most important facets in swine production. Although our current methods of selection are effective, there is still a large amount of variation in sow reproductive performance traits such as pigs per sow per year (PSY). Therefore, the objective of this study was to determine if on-farm phenotypic traits at 21 d postnatal (PN) or perinatal environmental factors could predict sow reproductive performance. Data were prospectively collected from 2,146 gilts born on a commercial sow production facility and included birth and weaning weights, vulva length and width at 21 d PN, birth and nursing litter size, days nursed, average daily gain from birth to weaning, and age at first estrus. Of the initial animals, 400 (17%) were selected for the sow herd, 353 remained after removal of animals culled for non-reproductive reasons. Animals were assigned to 1 of 5 reproductive performance categories based on observation of estrus or pigs per sow per year (PSY) across two farrowings: High Fertility (HF; 23%; n = 82; ≥26 PSY), Middle Fertility (MF2; 12%; n = 43; 20–25 PSY), Low Fertility (MF3; 15%; n = 54; <20 PSY), Infertile-Estrus (IFe; 10%; n = 36; estrus, no pregnancy), and Infertile-No Estrus (IFno; 39%; n = 138; no estrus, no pregnancy). Generalized linear model analysis indicated vulva width (P = 0.03) was related to PSY, however, it only explained 1.5% of the total variation in PSY. To determine if preweaning variables were predictive of gilt fertility outcome, animals were grouped as those that became pregnant (n = 179) or not (n = 174). Vulva width tended to be greater in fertile animals versus infertile (P = 0.07). Binomial regression analysis revealed a positive relationship between vulva width and gilt fertility, however, this relationship is not strong enough to make sow herd selection decisions.

Effects of flush feeding strategy before breeding on reproductive performance of modern replacement gilts: impacts on ovulation rate and litter traits

AbstractThe effects of two feed levels offered during two estrous cycles before insemination were evaluated on the reproductive performance of gilts. A total of 93 gilts (PIC Hendersonville, TN) were individually housed and manually fed twice a day with 2.1 or 3.6 kg/d of a corn and soybean meal-based diet (3.15 Mcal ME/kg and 0.64% standardized ileal digestible lysine), during two estrous cycles before breeding (cycle 1, between first and second estrus; cycle 2, between second and third estrus). Gilts were weighed at the beginning of the experiment, at second and third estrus, and at slaughter (30.2 ± 1.2 d of gestation). Follicles were counted at second estrus, and the embryo-placental units and the corpora lutea were individually counted, measured, and weighed at slaughter. Gilts fed 3.6 kg/d had greater BW gain during cycle 1 and cycle 2 (P < 0.001; + 9.8 kg and + 10.0 kg, respectively) becoming heavier at second and third estrus (P < 0.001). At second estrus, gilts fed 3.6 kg/d had 1.6 more medium-large follicles (P = 0.074) but no difference in follicle size (P = 0.530) was observed. Gilts fed 3.6 kg/d in cycle 1 or cycle 2 had a greater ovulation rate at third estrus (P < 0.016) than those receiving 2.1 kg/d. Also, 3.6 kg/d in cycle 2 increased early embryo mortality (P = 0.006; 2.3 vs. 1.1 dead embryos) and consequently reduced total embryo survival (P = 0.002; 84.6 vs. 90.1%). Gilts fed 3.6 kg/d during cycle 1 had two more total embryos (P < 0.001; 17.2 vs. 15.1) and two more vital embryos on day 30 (P < 0.001; 16.7 vs. 14.5) in comparison with gilts fed 2.1 kg/d. The coefficient of variation for placental length was greater for gilts fed 3.6 kg/d during cycle 1 (P = 0.003). No further significant effects of feeding levels were observed on embryo and placental traits (P ≥ 0.063). These results suggest that the feeding level during the first cycle after pubertal estrus is crucial to set ovulation rate and potential litter size for breeding at next estrus. However, flush feeding gilts before insemination can negatively impact litter size by reducing embryo survival when breeding at third estrus.

Age and weight at first mating affects plasma leptin concentration but no effects on reproductive performance of gilts.

The objective of this study was to verify the best mating age of gilts at the first parity. Gilts (n = 86) were divided into nine groups in a factorial arrangement with three Ages (AG1, ≤ 220 d; AG2, 220 to 240 d; AG3, 240 ≤ d), and three weights (WT1 ≤ 140 kg; WT2, 140 to 149 kg; WT3, 150 ≤ kg). A higher body weight gain in AG2 sows during gestation. Sows in AG2 group showed a higher body weight gain at first parity and backfat gain in the parity 2 and 3 during gestation. A greater insulin–like growth factor-1 (IGF-1) was observed in AG1 sows compared with AG3 sows at weaning in the second parity. Sows in WT1 group showed a significant positive effect on the plasma IGF-1 at breeding and weaning time in parity 2. Sows in AG3 group showed a higher plasma leptin at breeding, farrowing, and weaning in the parity 1, and at farrowing in parity 2. Sows in WT3 group showed a higher plasma leptin at breeding, farrowing, and weaning in the parities 1 and 2. Considering the insignificant longevity results, the most efficient time for gilts insemination can be at 220 d when their body weight is 140 kg or lower.

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.

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 replacement gilt: Current strategies for improvement of the breeding herd

The efficiency of swine production is affected by many factors. One of the most economically important factors is gilt reproductive performance. To achieve satisfactory results in breeding, both environmental and genetic factors must be monitored and constantly improved. For many years, intensive selection in the swine industry for increased carcass muscle to fat ratio has led to deterioration in some reproductive traits (eg, less favorable development of the reproductive system in gilts, problems with fertilization, large litters but tiny piglets). In recent years, many producers have focused on increasing litter size and weaning weights of piglets in addition to an emphasis on increasing sow productive life span. In replacement gilts, the systematic evaluation of both reproductive and structural soundness is of paramount importance. The main aim of this review is to summarize the current criteria for selecting replacement gilts.

313 Effects of Standardized Ileal Digestible Lysine Intake during Lactation on Litter and Reproductive Performance of Gilts.

313 Effects of Standardized Ileal Digestible Lysine Intake during Lactation on Litter and Reproductive Performance of Gilts.