Repeat breeding and subsequent reproductive performance in Swedish Landrace and Swedish Yorkshire sows

The objective of the present study was to analyse the association between repeat breeding (RB) in gilts/sows and their subsequent reproductive performance as well as the impact of interactions between repeat breeding and factors like parity number, boar breed, season and mating type (MT) on subsequent reproductive performance in Swedish Landrace (L) and Swedish Yorkshire (Y) sows. Data analysed included 7040 sows (3654 L and 3386 Y), farrowing during January 1994 until December 1999 in 11 L and 8 Y nucleus herds. The study was assigned as a cohort design and the aim was to study gilts/sows from their first mating as gilts until mating after third parity. Analysis of variance was applied to continuous data and logistic regression was applied to categorical data. Percentages of litters as a result of repeat breeding in sow parities 1-3 were 6.1, 12.0 and 6.3% for L sows and 6.7, 13.1 and 7.4% for Y sows. For parity 3, the incidence of litters resulting from repeat breeding was significantly higher (P<0.001) in Y than in L sows. The proportion of irregular return to oestrus (>24 days after first mating) was higher (P<0.01) in primiparous sows than in multiparous sows (69% versus 61%). On average, litters resulting from repeat breeding were larger (P<0.001) than litters resulting from non-repeat breeding (NR) (about 0.5 piglets per litter) in both L and Y sows. For Y sows, if the previous litter was a result of repeat breeding, the subsequent reproductive cycle had 2.7% higher RR (P<0.05) and 2.4% lower FR (N.S.) compared with sows that were not repeat bred. The same trend was found in L sows (1.4% higher RR and 1.3% lower FR) but the differences were not significant. Among the sows removed from the herds, about 24% of L and 28% of Y were culled due to reproductive problems (gilts not included). In addition, a number of sows from these nucleus herds were also culled due to low breeding value and poor conformation.     

Oregano improves reproductive performance of sows

Natural herbs are being explored as alternatives to antimicrobials. The objective of the present study was to determine the effect of strategic addition of oregano to prefarrowing and lactation diets of sows under field conditions. Alternate farrowing groups were given diets containing 1000 ppm oregano (dried leaf and flower of Origanum vulgare, enriched with 500 g/kg of cold-pressed essential oils of O. vulgare) in prefarrowing and lactation diets. Overall, 801 oregano-treated sows, including 601 primiparous and 1200 multiparous (parity 2.99 +/- 0.43, mean +/- S.E.) and 1809 untreated control sows (705 primiparous and 1104 multiparous; parity 3.04 +/- 0.38), were used. Sows fed oregano had lower annual sow mortality rate (4.02 +/- 0.4% versus 6.92 +/- 1.11%, mean +/- S.E.; P = 0.003), lower sow culling rate during lactation (8.01 +/- 1.11% versus 14.02 +/- 1.33%, P = 0.02), increased farrowing rate (77.02 +/- 2.31% versus 69.91 +/- 2.32%, P = 0.01), increased number of liveborn piglets per litter (10.49 +/- 1.5 versus 9.95 +/- 1.22, P < 0.05), and decreased stillbirth rate (0.909 +/- 0.01 versus 0.807 +/- 0.01, P = 0.05). In addition, multiparous sows fed oregano had higher (P = 0.04) daily voluntary feed intake compared to non-treated sows (7.7 +/- 0.32 kg versus 7.0 +/- 0.42 kg, P = 0.04). Additional studies are needed to elucidate the effects of oregano on the gastrointestinal, immune and urogenital system in swine and to determine if it has any adverse effects.     

The effects of post-weaning progestagen treatment (Regumate) of early-weaned primiparous sows on subsequent reproductive performance

This study investigated the effects of feeding the orally active progestagen, altrenogest (Regumate) post-weaning on the subsequent reproductive performance of early weaned sows. Ninety (90) Large White/Landrace first parity sows were randomly assigned to three treatments. Treatment 1 (EW) and treatment 3 (CW) sows were weaned on day 12 and day 24 post-partum, respectively while treatment 2 sows (EW-R) were weaned on day 12 post-partum and received an individual daily dose of 20 mg of Regumate on days 13 to 24 post-partum inclusive. Each sow was mated naturally at least twice at the first post-weaning or post-treatment oestrus and slaughtered on days 25–28 of pregnancy to determine the number of corpora lutea and embryos. Regumate-to-oestrus and weaning-to-oestrus intervals were similar for EW-R and CW sows (6.2 vs. 5.6 days). However, both intervals were significantly shorter (P<0.01) than the weaning-to-oestrus interval of EW sows (7.3 days). An excellent synchronization of oestrus was achieved with Regumate treatment with 97% of treated sows in oestrus within 7 days of Regumate withdrawal compared with 64% for EW sows (P<0.01) and 87% for CW sows (P>0.05). Treatment with Regumate resulted in a significant increase in ovulation rate (16.9 vs. 15.4 and 14.9 for treatments EW-R, EW and CW, respectively; P<0.05) and a non-significant increase in early embryonic survival (77% vs. 68% vs. 68% for treatments EW-R, EW and CW, respectively; P>0.05). These results indicate that Regumate feeding is a potential management tool to alleviate the diminished reproductive performance associated with early weaning regimes since it leads to successful control of oestrus, higher ovulation and embryo survival rates and thus a greater potential litter size.     

Induction of puberty and subsequent reproductive performance

A trial was conducted over 3 years to evaluate the success of inducing puberty in heifers of young age and light weight and to evaluate their subsequent reproductive performance at first calving. The control heifers and the young age heifers were grown at a rate of .56 kg/day compared to .23 kg/day for the light weight heifers. Eleven days prior to the start of breeding, heifers in the young age and light weight groups received the Synchromate B treatment. Implants were removed after 9 days. Average age and weight at breeding were 407, 334 and 406 days and 266, 239 and 243 kg for control, young age and light weight groups, respectively. After a 45-day breeding season 91, 47 and 81% of the heifers in the control, young age and light weight groups, respectively, (P<.05) had been in estrus. Pregnancy rates of the heifers that came into estrus were 67, 7 and 63% for the control, young age and light weight heifers, respectively, (P<.05) at the end of the 45-day breeding season. In the control and light weight groups 95 and 79% (P<.05) of the heifers that were diagnosed pregnant calved. Postpartum interval was 24 days shorter (P<.05) in the light weight heifers suckling calves and calf survival was 16% lower (P<.01) in the light weight group compared to the control heifers.     

Influence of leptospirosis on reproductive performance of sows in Brazil

The purpose of this study was to investigate the association between seropositivity for the most frequent Leptospira serovars and reproductive losses in sows in Brazil. Serum samples from 351 sows from 18 herds (in the state of Rio de Janeiro, Brazil) with low reproductive efficiency were tested (microscopic agglutination) for antibodies against serovars of Leptospira. Antibodies were detected in serum samples of 66.1% of all sows, most frequently serovar icterohaemorrhagiae (43.1%), followed by pomona (18.1%) and tarassovi (9.9%). Seroreactivity to icterohaemorrhagiae and pomona were associated (P<0.05) with impaired reproductive performance (and substantial economic loss). Seroreactivity for pomona was associated (P<0.05) with stillborn piglets and mummified fetuses, whereas seroreactivity to icterohaemorrhagiae was associated (P<0.05) with the number of piglets born dead.     

Factors influencing the postweaning reproductive performance of sows on commercial farms

The objective of this study was to investigate the effects of various factors, including lactational feed intake, on the reproductive performance of sows in commercial herds. The 4 measures of reproductive performance were weaning-to-first-service interval, weaning-to-conception interval, litter weight at weaning, and subsequent litter size. Parity, farrowing season, lactation length, farrowing-to-conception interval, litter size, and lactation feed intake were investigated as risk factors common to the 4 measures of post-weaning reproductive performance. Using 4 basic multiple regression models for each measure, the least-square means for sets of factors were compared using the GLM procedure of SAS. Parity 1 sows had the longest weaning-to-first-service interval and weaning-to-conception interval, and the lighter litter weight at weaning (P < 0.05) than mid-parity sows. Sows in Parities 2 to 5 had larger subsequent litter size (P < 0.05) than those in Parities 1 and >/= 7. Sows farrowing in summer and spring had the longest and second longest weaning-to-conception interval (P < 0.05), respectively, while sows farrowing in summer had longer weaning-to-first-service interval than those that farrowed in spring (P < 0.05). Sows farrowing in summer produced the lightest litter weight at weaning (P < 0.05). No differences in subsequent litter sizes were found due to farrowing season (P > 0.10). As lactation length increased, weaning-to-first-service interval and weaning-to-conception interval decreased, and litter weaning weight increased. Longer lactation length and farrowing-to-conception interval were associated with larger subsequent litter size (P < 0.05). Litter size did not affect weaning-to-first-service interval or weaning-to-conception interval. Larger litter sizes were associated with heavier litter weight at weaning. Greater lactation feed intake improved the 4 measures of reproductive performance.     

Dietary l-arginine supplementation enhances placental growth and reproductive performance in sows

Suboptimal embryonic/fetal survival and growth remains a significant problem in mammals. Using a swine model, we tested the hypothesis that dietary l-arginine supplementation during gestation may improve pregnancy outcomes through enhancing placental growth and modulating hormonal secretions. Gestating pigs (Yorkshire?×?Landrace, n?=?108) were assigned randomly into two groups based on parity and body weight, representing dietary supplementation with 1.0% l-arginine–HCl or 1.7% l-alanine (isonitrogenous control) between days 22 and 114 of gestation. Blood samples were obtained from the ear vein on days 22, 40, 70 and 90 of gestation. On days 40, 70 and 90 of gestation, concentrations of estradiol in plasma were higher (P?<?0.05) in arginine-supplemented than in control sows. Moreover, arginine supplementation increased (P?<?0.05) the concentrations of arginine, proline and ornithine in plasma, but concentrations of urea or progesterone in plasma did not differ between the two groups of sows. Compared with the control, arginine supplementation increased (P?<?0.05) the total number of piglets by 1.31 per litter, the number of live-born piglets by 1.10 per litter, the litter birth weight for all piglets by 1.36?kg, and the litter birth weight for live-born piglets by 1.70?kg. Furthermore, arginine supplementation enhanced (P?<?0.05) placental weight by 16.2%. The weaning-to-estrus interval of sows was not affected by arginine supplementation during gestation. These results indicate that dietary arginine supplementation beneficially enhances placental growth and the reproductive performance of sows.     

Microclimate influences plant reproductive performance via an antagonistic interaction

Climatic conditions can influence plant reproduction directly, but also via changes in plant traits, interactions with animals, and the surrounding environment. Such indirect effects can often be complex and involve multiple steps including climatic effects on interacting species, and on the context in which these interactions occur. The joint effects of climatic variation and indirect effects in terms of plant-animal interactions have sometimes been assessed at larger spatial scales. However, less is known about how microclimatic variation affects within-population variation in reproductive performance, in spite of that it is becoming increasingly clear that variation in climatic conditions can occur over very short distances. We studied the direct and indirect effects of microclimate on within-population variation in reproductive performance of the plant Gentiana pneumonanthe in presence of the myrmecophagous and seed predator butterfly Phengaris alcon. We found that microclimatic effects on plant performance were mainly indirect, and that effects of temperature and moisture were interactive. The number of seeds per flower of G. pneumonanthe decreased in cold and moist microsites, and these effects were mediated by an increased oviposition by P. alcon in these microsites. The effects of soil temperature and moisture on the incidence of oviposition and plant performance were mediated by effects on plant phenology, density and phenology of neighbouring host plants, and host ant abundance. Plants that flowered earlier and where host ants were more abundant, and especially plants surrounded by fewer and later-flowering neighbours, produced fewer seeds per flower because of a higher incidence of oviposition. Our results demonstrate that effects of microclimatic variation on plant reproductive performance can be mostly indirect and largely mediated by species interactions. These findings highlight that among individual variation in small-scale environmental conditions within populations can cause variation in individual plant performance through multiple pathways.     

Effect of temperature and humidity on reproductive performance of crossbred sows in Thailand

This study investigated the influence of season, temperature, and humidity on the reproductive performance of sows under tropical conditions. Data were collected from 11 sow herds from January 2001 to June 2002. Temperature and humidity were recorded daily for each herd from January 2001 to February 2002. Semen used was collected from boars housed in conventional open-air stables (six herds) or in evaporative cooling stables (five herds). A total of 43,875 farrowing records were included in the statistical analysis. Fourteen-day moving averages of daily maximum temperature and minimum humidity were calculated and merged with each reproductive record. ANOVA was applied to the reproductive records. In addition to the fixed effects included in the statistical models (e.g. system, season, parity, temperature, and humidity), the random effect of herd within system was included. The total number of piglets born was analyzed in relation to the climate at previous weaning (NTB-w), at mating (NTB-m), and at farrowing (NTB-f). The housing system of the boars had no significant effect on any of the reproductive variables analyzed. Season (2-month periods) as well as parity number had a significant effect on all reproductive variables analyzed. Increased length of previous lactation had a significant and favorable effect (P < 0.001) on NTB-w, NTB-m, and weaning-to-first-service interval. There were indications that high temperature and humidity (recorded at the herd level) at previous weaning/mating or at farrowing had negative effects on litter size, but these negative influences were not consistent.     

Prostaglandin F2alpha supplemented semen improves reproductive performance in artificially inseminated sows

The objective of this study was to assess the effects of the addition of prostaglandin F2alpha (PGF2alpha) to semen, to increase reproductive performance in sows. Sows in 11 large production units, were inseminated (AI) either with PGF2alpha enriched fresh semen (group 1, n=1258) or with untreated fresh semen (group 2, n=1101). Conception rate, regular return to estrus, farrowing rate, subsequent total and live-born litter size, subsequent weaning to estrus intervals, pigs born and pigs weaned per sow per year were evaluated. Conception and farrowing rates, as well as regular returns to estrus were altered beneficially (P<0.001) with PGF2alpha supplemented semen. Subsequent total-born (P<0.06) and subsequent live-born (P<0.15) litter size, as well as subsequent weaning to estrus intervals (P<0.22), were not affected to the same extent. Total pigs born (P<0.05) and pigs weaned (P<0.04) per sow per year were increased by using PGF2alpha supplemented semen.     

Early-weaned sows: altrenogest therapy, estrus, ovulation, and reproductive performance

Early weaning is a technique used to increase swine health status, and may cause consequences in reproductive performance of sows. An experiment was performed to evaluate these effects in a herd of sows, with weaning at 9 or 10 days post-farrowing, located in west of Minas Gerais, Brazil. Large-White sows (n=102), with three or four previous parturitions were randomly allocated to three treatment groups: T1: artificial insemination (AI) at first post-weaning estrus of the sows; T2: AI at second post-weaning estrus, T3: AI at first estrus, after an administration of a daily individual dose of 20 mg of altrenogest from 5 to 8 days post-weaning. The duration of the first post-weaning estrus did not differ among treatment groups; however, the second estrus of the T2 group was of shorter duration relative to the other treatment groups (P< or =0.035). Ovulation occurred earlier at the second estrus of the T2 group, compared with the T1 and T3 groups (P< or =0.027), being similar to that at the first estrus of T2 group (P=0.177). The relationship of the timing between ovulation and estrus was similar among treatment groups (P> or =0.221). There was no difference in farrowing rate among treatment groups (P> or =0.313). The T2 group produced a mean of 2.5 more piglets per litter (P=0.002). In conclusion, the use of altrenogest did not increase the reproductive performance of early-weaned sows.     

The impact of Leptospira seropositivity on reproductive performance in sows in southern Viet Nam

A serologic survey was conducted among sows in the Mekong delta in southern Viet Nam to investigate associations between leptospiral seropositivity and reproductive performance. Data were collected from a total of 339 sows in lactation or gestation, from four large-scale state farms on three occasions. The seroprevalence for Leptospira interrogans serovar (sv) autumnalis was 32%, for L. interrogans sv bratislava 29%, for L. kirschneri sv grippotyphosa 13%, for L. interrogans sv icterohaemorrhagiae 27%, for L. interrogans sv pomona 5%, and for L. borgpetersenii sv tarassovi 13%. The reproductive parameters number of days from weaning to service (WSI), number of piglets born, number of piglets born dead, and number of piglets born weak, were evaluated. Seropositivity for sv tarassovi was associated with 0.8 more dead piglets per litter (P = 0.06), and sv grippotyphosa with a 1 day longer WSI (P = 0.06). There were no significant associations between reproductive performance and sv autumnalis, sv bratislava, sv pomona, and sv icterohaemorrhagiae. It is concluded that seropositivity for Leptospira can be associated with impaired reproductive performance even in areas where a high degree of immunity among sows is expected.     

Effect of PG600 and adjusted mating times on reproductive performance in weaned sows

The administration of PG600 to sows at weaning induces >90% of sows to return to estrus within a week, but farrowing rate and litter size are often not improved. This study evaluated the effects of adjusted artificial insemination (AI) times based on weaning to estrus interval (WEI) and estrus to ovulation interval (EOI) following PG600. All sows were given PG600 at weaning and allotted to adjusted (ADJ, n=47) or non-adjusted (NA, n=46) mating times after the onset of estrus. Adjusted mating involved: (1) 2-3 days WEI, AI at 36 h and 48 h; (2) 4 days WEI, AI at 24h and 36 h; (3) 5 days WEI, AI at 12h and 24h; and (4) 6-7 days WEI, AI at 0 h and 12h. Mating for NA occurred at 0 h and 24h after onset of estrus. There was no effect of treatment on return to estrus (92.9% versus 92.5%) or ovulation (92.7% versus 92.5% for ADJ and NA, respectively). The proportion of first AI occurring within 24h prior to ovulation was increased (83.8% versus 50.0%) and closer to ovulation for ADJ compared to NA treatment (19.4h versus 27.3h, P<0.05). Treatment did not influence (P>0.10) the proportion of second AI occurring within 24h of ovulation (72.8% versus 56.6%) but did influence (P<0.05) the interval from second AI to ovulation for ADJ compared to NA (10.6h versus 3.3h). The ADJ treatment increased (P<0.05) the proportion of sows that received an AI within 24h before ovulation (98.8% versus 87.0%). However, treatment did not influence pregnancy (87.4%) or farrowing (79.5%) rates but the NA treatment tended to increase (P<0.10) total number of pigs born (11.8 versus 8.9). In conclusion, while AI times for ADJ appeared to occur within optimal periods, farrowing rates were not improved and litter size decreased, suggesting that two AI at 12h intervals and closer to the time of ovulation may be detrimental. Overall, these data suggest that for sows injected with PG600 at weaning and receiving two AI, breeding at 0 h and 24h after onset of estrus is recommended.     

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 retention of fetal membranes on subsequent reproductive performance of dairy ewes

Seventy-one pairs of ewes with or without retention of fetal membranes in the previous lambing season, were included in a cohort study of 25 flocks in southern Greece; in 27 pairs regulation of the breeding cycle was applied, whilst in the other 44 pairs natural mating took place. The following measures of reproductive performance were calculated: cycling rate, mating rate, return-to-estrus rate, abortion rate, lambing rate, total lambs born per ewe, liveborn lambs per ewe, stillbirth rate, lamb-bodyweight per ewe; furthermore, the incidence risk of retention of fetal membranes during the lambing examined in this study was also calculated. No statistically significant differences were observed in the reproductive performance among ewes that had or had not retained their fetal membranes during the previous lambing, whether the breeding cycle was regulated or not. The incidence risk of retention of fetal membranes among ewes that had not retained its placenta in the previous lambing was 1.6%, whilst that among ewes that had retained its placenta in the previous lactation was 0%. It is concluded that retention of fetal membranes did not appear to adversely affect subsequent reproductive performance of ewes.     

Effect of a GnRH analogue (Maprelin) on the reproductive performance of gilts and sows

The ability of peforelin (l-GnRH-III) to stimulate follicular growth, FSH release, and estrus in gilts after altrenogest treatment and in sows after weaning was investigated. In three farrow-to-wean herds, with at least 600 sows and average production performance, 216 gilts, 335 primiparous, and 1299 pluriparous sows were randomly allocated to three treatments: peforelin (M group: Maprelin), eCG (F group: Folligon), and physiological saline solution (C group). Animals were treated 48 hours after their last altrenogest treatment (gilts) or 24 hours after weaning (sows). The weaning-to-estrus interval, estrus duration, estrus rate (ER), pregnancy rate, and total born (TB), live born, and stillborn (SB) numbers were recorded and compared between treatments for the different parity groups (gilts and primiparous and pluriparous sows). Follicle sizes were measured in representative animals from each group on the occasion of their last altrenogest treatment or at weaning, and also on the occasions of their first (FS1) and second (FS2) attempted inseminations. Blood samples were taken to determine FSH concentrations at weaning and 2 hours after injection, and progesterone concentrations 10 days after the first insemination attempt. The relative change in FSH concentrations was calculated. Significant differences were found for ER within 7 days of weaning in pluriparous sows (95%, 91%, and 90% for the M, F, and C groups, respectively, P = 0.005). Gilts in the F-group had high TB numbers, and pluriparous sows in the M group had high SB numbers (TB gilts = 13.6, 15.4, and 14.9 [P = 0.02] and SB pluriparous sows = 1.8, 1.4, and 1.7 [P = 0.05] for the M, F, and C groups, respectively). The M group had the highest FS1 (for gilts) and FS2 (for pluriparous sows) values: FS1 = 5.4, 4.9, and 4.9 mm [P = 0.02] and FS2 = 6.8, 5.3, and 6.3 mm [P = 0.03] for the M, F, and C groups, respectively. There were no significant differences between the different treatments within each parity group with respect to any of the other variables. Overall, peforelin treatment had small but positive effects on the ER and follicle growth in certain parity groups but did not seem to affect litter sizes or FSH and progesterone levels in sows on the occasions of the corresponding examinations.     

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.     

Effects of individual versus group housing system during the weaning-to-estrus interval on reproductive performance of sows

Selection of appropriate housing conditions for sows is critical for their physical health and long-term reproductive success. The present objective was to evaluate the influences of housing system postweaning (i.e., individual stalls (IS) or group pens (GP)), season and parity on piglet productivity of sows in a commercial setting. This study utilized 3 053 Polish Large White × Polish Landrace sows that were weaned at a rate of 20–30 animals per week at the median age of 4 weeks; 1 474 sows were moved into GP of seven to eight animals each, while 1 579 were placed in IS after weaning. Starting 2 days postweaning all animals were checked for estrus with a teaser boar and then artificially inseminated using 3 × 10⁹ spermatozoa per dose of an inseminate at the onset of heat and 24 h later. The proportion of sows showing the signs of standing heat at or before 6 days postweaning was greater (P < 0.05) for sows moved to GP compared with IS; this difference manifested mainly in second parity sows weaned in the summer and fall. Conception and farrowing rates were significantly higher (P < 0.01) and the weaning-to-estrus interval shorter in GP compared with IS sows in every season but autumn. Mean litter size was lower (P < 0.05) in IS groups in summer, autumn, and winter, and the number of live-born piglets/sow was lower (P < 0.05) for IS sows in the summer and fall. Beneficial effects of group housing on piglet productivity manifested up until the seventh consecutive farrowing and then began to wane. In summary, there was a significantly greater proportion of sows going estrus “on time” (i.e., < 7 days) in group housing compared to single stalls but this effect was confined to the second parity sows during the summer and fall months; these results suggest the existence of a seasonal and age-related aspect to sow fertility worthy of further investigation. While both housing systems have their pros and cons, our present results indicate that, in commercial settings, group housing postweaning improved nearly all reproductive parameters of sows.