Reproductive Performance Of Primiparous Sows Research Articles

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.

Heat wave exposure impairs reproductive performance in primiparous sows and gilts in a tropical environment.

We studied the effects of heat waves (HW), defined as three consecutive days with an ambient temperature ≥ 25°C and a temperature and humidity index (THI) > 74, on the reproductive performance of sows. Meteorological data were obtained from the National Institute of Meteorology and reproductive data from a commercial farm with 51,578 inseminations and 49,103 pregnancies from September 5, 2013, to July 12, 2019. Sows were divided into the following groups according to the parity order: group 1 (sows that did not experience HW on the day of insemination) and group 2 (sows exposed to HW on the day of insemination). The percentage of days that pregnant sows were exposed to HW was calculated as 0 to 25% (1), 26 to 50% (2), 51 to 75% (3), and > 75% (4). Out of a total of 2137days, there were 160 HW and more than 10 HW per month, except in May, June, and July. Gilts in group 2 showed a decrease in the percentage of gestation (98.21% and 98.78%, respectively, P = 0.0267) and the percentage of births compared with those in group 1 (95.53% and 96.61, respectively, P = 0.0065). Primiparous sows in group 2 had a higher percentage of abortions than gilts in group 1 (3.20% and 2.42%, respectively; P = 0.0334). Sows exposed to more than 50% HW during gestation produced more mummified piglets than sows exposed to less than 50% HW. The number of stillborn piglets was higher in sows exposed to temperatures above 25% HW during gestation. The occurrence of heat waves in gilts and primiparous sows impairs reproductive performance.

A comparison of the reproductive performance in primiparous sows following two timed artificial insemination protocols

Timed artificial insemination (TAI) is an efficient reproductive technology in batch farrowing production that aids management in pig farms. However, the effect of TAI on the reproduction performance is still controversial. This study aimed to evaluate the effects of two TAI protocols on the reproductive performance of primiparous sows. A total of 332 weaned sows were randomly allocated into three treatments. Sows assigned to Control (n = 110) were untreated and inseminated on each day in oestrus after weaning. Sows assigned to eG-TAI (n = 112) received equine chorionic gonadotropin (eCG) 24 h after weaning and gonadotropin-releasing hormone (Gonadorelin: GnRH) at oestrus, and were inseminated at 8 and 32 h later if oestrus at 0800, or 16 and 40 h later if oestrus at 1600. Sows assigned to 2e-TAI (n = 110) received eCG and GnRH 24 h and 96 h after weaning, respectively, and were inseminated 16 and 40 h after GnRH administration. Sows showing oestrus at GnRH administration or 64 h after were inseminated immediately, for a total of three inseminations. Ultrasonographic evaluations were performed to determine the follicular diameter and time of ovulation. Most sows in the 2e-TAI and eG-TAI groups ovulated 0–48 h after the GnRH injection. Our results indicated that oestrus rate within seven days after weaning in the experimental groups was higher, and weaning-to-oestrus interval was shorter than in the control group (99.3 h vs 113.5 h, P < 0.05). The breeding and farrowing rates in the experimental groups were significantly higher than in the control group (P < 0.05), while the numbers of total born, live-born and stillborn were not different among the three groups (Control: 12.7, 11.6 and 1.1; 2e-TAI: 12.4, 11.3 and 1.0; eG-TAI: 12.0, 11.4 and 0.4, respectively). These results indicated that TAI could ensure a high farrowing rate in primiparous sows under batch farrowing management.

Effects of heat stress on posture transitions and reproductive performance of primiparous sows during late gestation.

This study aimed to investigate the effects of heat stress on posture transitions of perinatal primiparous sows around the parturition period from 72h prepartum to 24h postpartum. The reproductive performance of sows was measured, and the relationship between posture transitions and reproductive performance was also analyzed. Ten primiparous sows were randomly assigned to thermoneutral (TN) (18-22°C; n=5) or heat stress (HS) (28-32°C; n=5) treatments. Posture transitioning, including the frequency of posture change, duration of dynamic posture (DP), and lateral lying with udder to the piglet creep box (PCB) during three periods (72h prepartum, sub-partum, and 24h postpartum, respectively), were recorded. Posture change frequency was significantly increased, starting from 24h prepartum to the onset of farrowing in both the TN (P<0.05) and HS (P<0.01) groups. Moreover, the peak value of posture change frequency in the TN group was concentrated during the 12h prepartum period, positively correlated with the quantities of head-first birth piglets and sub-partum duration, respectively. DP duration increased during the period of 24h prepartum and then decreased sharply (P<0.001 and P<0.05 for TN and HS groups, respectively). The duration of facing the udder to the PCB increased during sub-partum and postpartum TN (P<0.001). The duration of sub-partum (P<0.05) and delivery time of single piglets (P<0.01) in the HS group was prolonged, and piglets from the HS group had a lower weight gain than the TN group both at d10 (P<0.001) and weaning time (P<0.001). In conclusion, HS had obvious adverse effects on nursery behavior and reproductive abilities in perinatal primiparous sows, which resulted in poor growth performance of lactating piglets.

Effects of loose farrowing facilities on reproductive performance in primiparous sows.

The present study investigated the effects of loose farrowing type during gestation and after farrowing on reproductive performance and of lactating sows. A total of 22 primiparous sows (Landrace; average initial body weights [BW], 228.54 ± 12.79 kg) were allotted to one of two treatments on the basis of body weight. Sows were divided into two experimental groups, conventional farrowing crates (CON), and loosed-farrowing pens (LFP). The experiment duration was around 38 days ranging from 10 days before parturition to 28 days after parturition. Gestating sows at the age of 105 d were placed in gestational stalls (group housing). All the sows were fed a common diet according to the National Research Council requirements for lactation. Cross-fostering was performed within 1 day of parturition. From 1 day after weaning, estrus detection was performed twice-daily (0900 and 1730 h) for 10 min by boar exposure. There were significant effects of LFP housing type on the farrowing duration, and farrowing interval. At the farrowing time, none of the litter parameters including total born, stillborn, mummy, born alive piglets and total litter weight and piglet weight were affected. There were no effects of housing type on the mortality of piglets at d 1, 3, 7, 21, and 28. In conclusion, the result of this study showed that there is no performance difference between the crated or LFP sows, which indicate that the LFP housing has the potential to be used as an alternative to the crated house without any detrimental effects in reproduction performance of lactating sows.

Effect of altering the ratio of exogenous gonadotropins on reproductive performance of primiparous sows during the seasonal infertility period

At weaning, 150 primiparous sows were assigned sequentially to receive 400 IU equine chorionic gonadotropin (eCG) with 200 IU human chorionic gonadotropin (hCG) (Gn600), or 400 IU eCG with 400 IU hCG (Gn800), or served as untreated controls. Compared with control and Gn600, the Gn800 had increased estrus response by day 7 and reduced wean-to-estrus intervals (P &lt; 0.05). Compared with controls, both Gn600 and Gn800 increased numbers of large follicles (≥6 mm) at estrus detection (P &lt; 0.05) and the subsequent farrowing rates (P &lt; 0.05). Litter size was unaffected. These data demonstrate the efficacy of supplemental hCG for alleviating effects of seasonal infertility in primiparous sows.

DESEMPENHO REPRODUTIVO DE FÊMEAS SUÍNAS PRIMÍPARAS SUBMETIDAS OU NÃO À INTERVENÇÃO MANUAL AO PARTO NO SUDOESTE GOIANO

This study was performed in a production of piglets unit in southwest of Goias state and sought to characterize the reproductive performance of primiparous sows submitted or not to manual intervention at the labor parturition realized by vaginal palpation. Farrowing information was collected from 1.023 parity 1 sows. Females were divided into control group (n=945) and intervention (n=78). The percentage of females submitted to manual intervention at farrow was 7.6%. Among the categories of litter size, there was no difference in the percentage of females with genital

Influence of lactation length and gonadotrophins administered at weaning on fertility of primiparous sows

The aim of this study was to determine the effect of lactation length and treatment with gonadotrophins at weaning on reproductive performance of primiparous sows. After 3 wk of lactation, primiparous sows were either weaned (W3; n=273) or received a 7-d-old foster litter for a further 14 d of suckling (W5; n=199). At final weaning (3 wk or 5 wk lactation) sows were randomly assigned to receive an injection of 400 IU equine chorionic gonadotrophin plus 200 IU human chorionic gonadotrophin (PG600®; W3+P; n=108 and W5+P; n=96) or no injection (W3; n=165 and W5; n=103). Sows were inseminated at first observed estrus after final weaning and 24h later. The proportion of sows showing estrus by 6 d post-weaning was greater (P<0.01) for W3+P (86%) compared to W3 (64%), however, there was not a difference (P=0.13) for W5+P (79.4%) compared to W5 (69.1%). There was no effect of either lactation length or gonadotrophin treatment on farrowing rates or on the proportion of sows culled before breeding. Total born litter size was smaller (P=0.05) for W3+P (11.7±0.4) compared to W3 (12.6±0.3). However, sows that lactated for 35 d had larger litters than sows that lactated for 21 d regardless of gonadotrophin treatment (14±0.5 and 14.5±0.4 for W5+P and W5, respectively; P<0.001). These data indicate that for primiparous sows, a longer lactation improves total born litter size at their next farrowing. Gonadotrophin treatment is useful in shortening the weaning to estrus interval but subsequent total born litter size may be negatively affected.

The Post‐Cervical Insemination does not Impair the Reproductive Performance of Primiparous Sows

The study evaluated the reproductive performance of primiparous sows submitted to post-cervical insemination (PCAI) compared with cervical artificial insemination (CAI). Difficulty with catheter introduction, the occurrence of bleeding or semen backflow during insemination, and volume and sperm cell backflow up to 60min after insemination were also evaluated. Sows were homogenously distributed, according to body weight loss in lactation, lactation length, weaned piglets, weaning-to-oestrus interval and total born in previous farrowing, in two treatments: PCAI (n=165) with 1.5×10(9) sperm cells in 45ml (2.4±0.04 doses per sow) and CAI (n=165) with 3×10(9) sperm cells in 90ml (2.5±0.04 doses per sow). During PCAI, sows were inseminated in the absence of boars. Transabdominal real-time ultrasonography was performed at oestrus onset, immediately before the first insemination and at 24h after last insemination. There was no difference (P>0.05) between treatments in farrowing rate (91.5%×89.1%) and litter size (12.5×11.9 piglets born, respectively for PCAI and CAI sows). Successful passage of the intrauterine catheter in all the inseminations was possible in 86.8% (165/190) of sows initially allocated to PCAI treatment. Difficulty of introducing the catheter in at least one insemination did not affect the reproductive performance of PCAI sows (P>0.05). Bleeding during insemination did not affect (P>0.05) the farrowing rate in both treatments, but litter size was reduced in CAI and PCAI sows (P≤0.06). Percentage of spermatozoa present in backflow within 1h after insemination was greater in CAI than PCAI sows (P<0.01). More than 85% of primiparous sows can be successfully post-cervical inseminated with doses containing 1.5×10(9) sperm cells in the absence of the boar during insemination without impairing the reproductive performance.

Effects of Breeding at the Second Oestrus or After Post‐Weaning Hormonal Treatment with Altrenogest on Subsequent Reproductive Performance of Primiparous Sows

This study investigated the effects of breeding at the second oestrus after weaning or after feeding an orally active progestagen (altrenogest) on the subsequent reproductive performance of primiparous sows. After 3 weeks of lactation, 663 weaned sows of two genotypes were allocated into three groups: G1--breeding at the first oestrus after weaning; G2--breeding at the second oestrus after weaning and G3--treatment with altrenogest for 5 days after weaning and breeding at the first oestrus after the end of the treatment. Body weight at breeding was lower in G1 and G3 than in G2 sows (p < 0.05). The interval to show oestrus was similar for G1 and G2 groups (p > 0.05) but higher (p < 0.05) than that observed in G3 group. Within genotype A, percentages of females in oestrus within 10 days were not different (p > 0.05) among groups, whereas in genotype B, more G1 and G2 sows (p < 0.05) showed oestrus than G3 sows. In both genotypes, lower farrowing rates were observed in G3 than in G1 and G2 sows (p < 0.05) and a greater litter size (p < 0.05) was observed in G2 sows. In genotype A, the number of total born piglets was similar for G1 and G3 groups (p > 0.05), whereas in genotype B, G1 sows had a greater litter size than G3 sows (p < 0.05). Body weight at weaning and at breeding was similar (p > 0.05) between farrowed and non-farrowed sows in all groups. Reproductive performance is not improved in primiparous sows treated with altrenogest during 5 days after weaning. The reproductive performance of genotype B sows is compromised in Control and Altrenogest-treated sows but not in those bred at the second oestrus after mating. Breeding at the second oestrus after weaning allows primiparous sows to gain weight between weaning and service, and increases their farrowing rate and subsequent litter size.

Effects of dietary energy and lysine intake during late gestation and lactation on blood metabolites, hormones, milk compositions and reproductive performance in primiparous sows

The effects of energy and lysine intake during late gestation and lactation on the reproductive performance of primiparous sows were evaluated using 36 gilts. Sows were allocated to six dietary treatments according to a 3 × 2 factorial arrangement and each treatment had six replicates. Three energy levels [low (EL), medium (EM) and high (EH)] and two lysine levels [low (LL) and high (HL)] were used. Gilts with HL intake had more weight (P = 0.004) and backfat thickness (P = 0.047) gain during gestation. Similar changes in sow body conditions were observed during lactation. HL intake resulted in higher litter birth weight (P = 0.001), weaning weight (P &lt; 0.001) and growth rate (P &lt; 0.001) and shortened wean-to-estrus interval (P= 0.001). Energy intake influenced the fat and lactose content while lysine intake influenced the total solids and protein content in milk and colostrum. Gilts with HL had higher insulin and lower creatinine levels during post farrowing and weaning, while triglyceride concentration at weaning increased with increasing of energy intake. The basal and pulses of LH were also influenced by lysine intake. In conclusion, higher lysine intake than those recommended by National Research Council (1998) could improve performance during late gestation and lactation in primiparous sows. Key words: Energy, lysine, gestation, lactation, sows

Reproductive performance in primiparous sows after postweaning treatment with a progestagen

The purpose of this study was to determine whether administration of altrenogest (Regumate; Roussel-Uclaf, París, France) to primiparous sows would improve estrus synchronization rate and reproductive efficiency of the herd, measured in terms of the weaning-to-estrus interval (WEI), the weaning-to-first-fertile-estrus-interval (WFEI), rate of sows repeating estrus, and conception rate at first estrus. First-parity sows (Landrace x Large White) from a commercial herd received altrenogest, 20 mg per sow per day, for 5 consecutive days starting the day after weaning. A group of untreated sows acted as controls. The percentage of sows showing estrus 4 to 7 days postweaning (controls; 65.6%) or 4 to 7 days after treatment ended (8 to 11 days postweaning) was higher (P &lt; .05) in the altrenogest-treated group (86.2%). Sows were mated naturally twice at the first estrus after weaning and pregnancy was diagnosed by ultrasonography 23 to 24 days later. There were no differences between treated and control sows in means of WEI, WFEI, rate of sows repeating estrus, or conception rate to first service. Litter size at farrowing, number of live born piglets, number of stillborn piglets, preweaning mortality, and weaned litter size were also similar between groups.

Effect of gilt development diet on the reproductive performance of primiparous sows.

The objective of this study was to evaluate the effect of development diet on first-parity reproductive performance across different genetic types of females. Gilts (n = 708) 8 to 15 d of age from five genetic lines were assembled using a segregated early weaning protocol. Genetic types represented industry variation for reproductive capacity and lean growth potential. Sampling procedures were not designed to evaluate performance differences among the genetic lines. When the gilts weighed approximately 20 kg, they were moved from the nursery facilities to a slotted-floor, environmentally controlled facility, and seven to eight animals within a genetic type were penned together. When the gilts weighed approximately 40 kg, they were moved to a modified open-front facility. Nineteen gilts were allotted to each pen (.92 m2 per pig). Gilts were assigned to one of three development diets at 120 d of age. Diet 1 (high energy, 18% CP) and Diet 2 (high energy, 13% CP) were provided for ad libitum consumption to the assigned gilts until they weighed approximately 113 kg. Gilts receiving Diet 3 (23% CP) were fed 1.8 kg/d from 82 kg until they reached 180 d of age (approximately 100 kg). Gilts were fed 2 kg daily of a gestation diet from 180 d to 200 d of age and 2.7 kg daily from 200 d until mating. To stimulate the estrus cycle, gilts were commingled and exposed to vasectomized boars beginning at 180 d of age. Gilts that were in estrus and 210 d of age or older were artificially inseminated with commercial semen. Gilts not detected in estrus within the first 50 d of observation were injected with PG600 and estrus detection continued for 30 additional days. Of the 657 gilts entering breeding pens, 422 farrowed. Bred gilts were distributed to 10 cooperator facilities before farrowing. Mixed model procedures were used to analyze the data. Significant (P < .05) genetic type x gilt development diet interactions were found for number of pigs born, number of pigs born alive, total litter birth weight, and litter birth weight of pigs born alive. Significant interactions consistently involved one genetic line and gilt development Diets 1 and 2. Gilts from this genetic line-diet subclass had poorer farrowing performance (P < .05) than gilts from the same line fed development Diet 3. Only two other significant genetic line x gilt development diet interactions were found. Gilt development diet had little influence on first-parity reproductive performance.

Dietary energy source at two feeding levels during lactation of primiparous sows: I. Effects on glucose, insulin, and luteinizing hormone and on follicle development, weaning-to-estrus interval, and ovulation rate.

Our objective was to study the effects of dietary-induced insulin enhancement during and after lactation on the reproductive performance of primiparous sows. During a 21-d lactation period, 48 sows were allotted to a 2x2 factorial experiment. Treatments were feeding level (high or low; 44 MJ or 33 MJ NE/d) and dietary energy source (fat or starch). After weaning, all sows received the same amount of feed (31 MJ NE/d from weaning to estrus and 17.5 MJ NE/d from breeding until slaughter) of the same energy source as fed during lactation. On d 7, 14, and 21 of lactation and d 22 (weaning), blood samples were taken every 12 min for 12 h and analyzed for plasma glucose, insulin, and LH. Sows were slaughtered on d 35 of the subsequent pregnancy, and ovulation rate was assessed. During lactation, postprandial plasma glucose and insulin concentrations were higher for sows fed the starch diet than for those fed the fat diet (P<.001), whereas feeding level had no effect. Basal and mean LH concentrations were not affected by treatments. The LH pulse frequency on d 7 of lactation was greater for sows fed the starch diet than for those fed the fat diet (.52 vs .17 pulses/12 h; P = .03). The high compared with the low feeding level resulted in a greater LH pulse frequency on d 21 of lactation (.89 vs .47 pulses/12 h; P = .05) and on d 22 (8.63 vs 5.77 pulses/12 h; P = .02), in a higher percentage of sows that exhibited estrus within 10 d after weaning (96 vs. 63%; P = .01), and a tendency for a higher ovulation rate (18.0 vs. 16.2; P = .09). Plasma glucose and insulin concentrations were not related to any of the LH traits. The LH pulse frequency after weaning was related to the weaning-to-estrus interval (WEI) and was best explained by a linear-plateau model. In sows fed the low feeding level, follicle size after weaning was correlated with LH pulse frequency after weaning and with the WEI, whereas in sows fed the high feeding level these correlations were not significant. Our results indicate that an improved dietary-induced insulin status during and after lactation does not overcome the inhibitory effects of lactation on subsequent reproduction at any of the feeding levels.

Effects of dietary lysine intake during lactation on blood metabolites, hormones, and reproductive performance in primiparous sows.

Effects of three dietary lysine (protein) concentrations during lactation on metabolic state, protein metabolism, reproductive hormones, and performance were investigated in 36 primiparous sows. Sows were assigned randomly to one of three diets containing .4% (low lysine, LL), 1.0% (medium lysine, ML), or 1.6% (high lysine, HL) total lysine from intact protein sources. All diets contained 2.1 Mcal NE/kg and exceeded the recommended requirements for all other nutrients. Actual lysine intakes over an 18-d lactation were 16, 36, and 56 g/d for sows fed LL, ML, and HL, respectively. Fractional breakdown rate of muscle was determined on d 4 and 15 of lactation by using a three-compartment kinetic model of 3-methylhistidine metabolism. Increasing lysine intake during lactation did not affect fractional breakdown rate of muscle on d 4 of lactation but decreased it on d 15 (P < .05). Sows fed LL had a reduced number of LH pulses on d 12 and 18 (P < .05) and reduced serum estradiol (E2) concentration on d 18 of lactation compared with sows fed ML and HL treatments. However, LH pulses and E2 concentrations were similar between ML and HL treatments (P > .35). Increasing lysine intake increased serum urea nitrogen (SUN) and postprandial insulin concentrations (P < .05) during lactation but had no effect on plasma glucose concentrations (P > .20). Sows fed HL had greater serum IGF-I on d 6 and 18 than sows fed ML (P < .05). Number of LH peaks was correlated with serum insulin concentration 25 min after feeding on d 6 and 18 (r = .31 to .41; P < .1) and pre- (r = .33 to .46) and postprandial (r = .30 to .58) SUN concentrations (P < .05) during different stages of lactation. Results indicate that, compared with medium lysine intake, low lysine intake increased muscle protein degradation and decreased concentrations of insulin, SUN, and estradiol and LH pulsatility. In contrast, high lysine (protein) intake increased SUN, insulin, and IGF-I, but did not increase secretion of estradiol and LH compared with medium lysine intake. Furthermore, nutritional impacts on reproduction may be mediated in part through associated effects on circulating insulin concentration.

The effect of immunoneutralization of PMSG at a gonadotropin-induced oestrus on the duration of ovulation and reproductive performance of sows

AbstractTwo experiments were performed to examine the effects of immunoneutralizing PMSG at the onset of oestrus on the reproductive performance of sows. In experiment 1, 12 multiparous sows received 750 i.u. PMSG at weaning and six sozus acted as controls and were injected with saline. At 84 h after PMSG injection, all sows received an injection of 500 i.u. human chorionic gonadotropin (hCG) and six of the PMSG-treated sows also received an injection of 750 i.u. of a monoclonal anti-PMSG serum. The ovaries of all sows were examined by real time ultrasonography at 60-min intervals from 36 to 48 h after hCG injection for evidence of ovulation. In sows observed to ovulate, there was no significant effect of treatment on the interval from hCG injection to the start of ovulation, the duration of ovulation or subsequent litter size. In experiment 2, 253 primiparous sows received injections at weaning of 750 i.u. PMSG (no. = 134), 400 i.u. PMSG plus 200 i.u. hCG (no. = 69) or served as controls (no. = 50). At breeding, 67 of the PMSG-treated sows received an injection of 750 i.u. of monoclonal anti-PMSG serum.More gonadotropin-treated than control sows were bred by 7 days after weaning (P &lt; 0·05). Farrowing rates were higher in sows receiving the PMSG followed by anti-PMSG and PMSG plus hCG than in controls (P &lt; 0·05), with those receiving PMSG alone being intermediate. There was no effect of treatment on subsequent litter sizes. These data indicate that the reproductive performance of primiparous sows may be improved by gonadotropin administration at the time of weaning. However, there was no advantage to using any particular hormone combination or anti-PMSG.

Effects of insulin administration at weaning on hormonal patterns and reproductive performance in primiparous sows.

Twelve primiparous sows were grouped into six pairs. One sow from each pair (T) received subcutaneous injections of porcine insulin as follows: pairs 1 and 2, 0.5 IU/kg at 07.00 h; pairs 3 to 6, 0.5 IU/kg at 07.00 and 15.00 h. Insulin administration was started one day before weaning and continued until the last day of post-weaning oestrus. Control sows (C) received physiological saline solution as a sham treatment. Blood samples were collected every 3 h from 09.00 to 21.00 h and, additionally, at 07.00 h during the period of insulin treatment. Additional blood samples were collected at 15-min intervals for 6 h for 2 days before and for 3 days after weaning, and for 12 h on the day of weaning (D35 of lactation). Exogenous treatment with insulin increased plasma levels of insulin (53 v 36 mU/l, P < 0.001) and decreased plasma levels of glucose (4.6 v 5.5 mmol/l, P < 0.001) in T-sows as compared to C-sows. During the treatment period, the average levels of cortisol (31 v 35 nmol/l, P < 0.001) and non-esterified fatty acids (0.13 v 0.16 mmol/l, P < 0.01) were lower in T-than in C-sows. No differences in glucagon or urea levels were observed between the two groups. Plasma levels of LH were higher in T- than in C-sows both before and during the treatment period. However, no differences in number of LH pulses/6h were found between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of altrenogest on litter size in primiparous sows

Aitrenogest (17 α -allyl-17-hydroxyestra-4,9,11-trien-3-one; Regumate Porcine; Hoechst Animal Health) is a synthetic progestagen which has been used to control and synchronise the ovarian cycle particularly in cyclic gilts. However progestagens have also been used in various species to induce and synchronise the first ovulation post partum. The present study was undertaken to determine the effect of altrenogest treatment on the reproductive performance of primiparous sows.

The Effect of Fractionated Weaning on Reproductive Performance in Primiparous Sows on a Commercial Farm

The Effect of Fractionated Weaning on Reproductive Performance in Primiparous Sows on a Commercial Farm

Effect of lactational and post weaning feeding on the reproductive performance of primiparous sows

A depression in sow reproductive performance at the second litter is frequently experienced in modern production. Reducing the loss of body reserves during lactation and increasing energy intake between weaning and service have been suggested as ways of increasing the size of the second litter. This trial investigated these possibilities.