Prevalence of Eimeria spp. in Sows at Piglet‐producing Farms in Germany

The prevalence of Eimeria infections was investigated in an initial survey in 54 sow herds of small (five sows) to large (1600 sows) size by random sampling (n = 1204). All sows of four Eimeria‐positive medium‐sized farms (63 or 130 sows) were re‐examined 40–99 days after the first visit. A follow‐up survey over the whole reproductive cycle was subsequently performed in a positive herd of 130 animals where faecal samples of 43 sows were repeatedly collected on seven successive farm visits. In 44 farms (81.5%) parasite stages (eggs of strongylids, Trichuris, Ascaris, Strongyloides, oocysts of Eimeria and Isospora) were identified in sow faeces, strongylids being the most prevalent intestinal parasites (34 farms resembling 63%) followed by Eimeria spp. (28 farms resembling 52%). Of the 1204 random samples collected during the initial survey 8.6% contained Eimeria oocysts. Oocysts of E. polita and E. debliecki were present in each of 25 Eimeria‐positive samples selected for species differentiation. Eimeria suis was diagnosed in 84%, E. scabra in 60%, E. porci in 52%, E. perminuta in 49% and E. spinosa in 20% of these specimens. At the second visit the prevalence rates of Eimeria infections had either increased or decreased. In the follow‐up study Eimeria infections were found to be most frequent (82%) at the service station. At the quarantine unit and the gestation stable 50 and 48% of the 43 sows were Eimeria positive. The lowest prevalence of Eimeria infection was observed in the farrowing unit (14%). With respect to the reproductive state of the sows highest infection rates were seen 2 weeks after weaning (72%) continuously decreasing until 2 weeks after farrowing (14%). A periparturient rise of oocyst excretion was not observed. The infestation rate remained low until 1 week before weaning (16%). Low infection intensities clearly dominated. Clinical disease was not associated with Eimeria infection.     

Control of Isospora suis-induced coccidiosis on a swine farm

Results of a program designed to control neonatal porcine coccidiosis on a total confinement, farrow-to-finish swine farm are reported. The control program consisted of washing, phenol disinfection, and steam cleaning of farrowing houses and treatment of sows with amprolium HCl before and after farrowing. Before initiation of the control program, 88.9% of the sows examined in the farrowing house were negative for coccidian oocysts, 9.9% were positive for Eimeria spp, and 1.2% were positive for Isospora suis. Most pigs nursing on sows before initiation of the control program had diarrhea at 5 to 10 days of age, which led to dehydration and weight loss. Morbidity was high, and mortality was moderate. Composite fecal samples from these litters were all positive (100%) for I suis. After initiation of the control program, 99.6% of the sows examined in the farrowing house were negative for coccidian oocysts and 0.4% were positive for Eimeria spp. Clinical signs of coccidiosis were rarely present in nursing pigs examined after the control program was initiated; however, I suis was still present in 19.8% of the composite fecal samples from pigs examined. An association between oocyst production in sows and I suis infections in pigs was not found in the present study. Oocysts of Eimeria spp were not found in the feces from the pigs.     

Reproductive Performance of Purebred Swedish Landrace and Swedish Yorkshire Sows: I. Seasonal Variation and Parity Influence

The objective of this retrospective study was to investigate the causes of variation in the reproductive performance of purebred Swedish Landrace (L) and Swedish Yorkshire (Y) sows. Data analysed comprised farrowings from 1994 through 1997 from 19 Swedish nucleus herds and included 20 275 litters from 6989 purebred sows (3598 L and 3491 Y). The main traits analysed were litter size, weaning-to-first-service interval (WSI), farrowing rate, remating rate and age at first farrowing. Analysis of variance was used for the statistical analysis of quantitative data. Logistic regression analysis was applied for binary data using the GLIMMIX macro in the SAS program. Factors included in the analyses were breed of sow, breed of boar, parity number, herd-year combination within breed, mating type (natural mating or artificial insemination), lactation length and month of the year. L sows, compared with Y sows, produced larger litters [11.61 vs 11.54 total born/litter (ns) and 10.94 vs 10.58 born alive/litter (P<0.001)] and had a longer WSI (5.5 vs 5.4 days, P<0.001), a higher farrowing rate (82.8 vs 80.9% units, P<0.05) and a lower remating rate (6.2 vs 8.8% units, P<0.001). On average, L sows were younger at first farrowing than Y sows (355.6 vs 368.6 days, P<0.001). The seasonal influence on WSI was greater for primiparous sows than for multiparous sows. Primiparous sows weaned from June to October had a longer WSI than those weaned from January to May or in November (P<0.05). Mating in August resulted in the lowest farrowing rate and the highest remating rate. The seasonal influence on farrowing rate and WSI was more pronounced in Y sows than in L sows. However, season had no significant influence on litter size in either L or Y sows.     

The Effects of the Periodical Use of In-feed Chlortetracycline on the Reproductive Performance of Gilts and Sows of a Commercial Pig Farm with a History of Clinical and Subclinical Viral and Bacterial Infections

The objective of this study was to assess the effects of in‐feed chlortetracycline (CTC) as a measure of preventing or minimizing infectious problems of reproductive failure in gilts and sows. In a farm of 400 Large White × Landrace gilts and sows with a clinical history of porcine respiratory and reproductive syndrome (PRRS) virus, the animals were treated with CTC. Treatment consisted of 10 g CTC sow/day for 15 days every 3 months. It improved the health status of sows by decreasing post‐farrowing clinical mastitis and vaginal discharges, abortions, return‐to‐oestrus and irregular return‐to‐oestrus rates. These beneficial effects had a positive impact on the performance of the litter. More piglets were born live and weaned. These positive effects improved with repeated use of CTC. The serological evidence of PRRS virus, Leptospira spp. and Chlamydia spp. and the subsequent beneficial use of the antimicrobial agent indicate that reproductive failure, possibly resulting from the bacterial agents can be controlled with in‐feed use of broad spectrum antimicrobials.     

Effects of different gestation housing types on reproductive performance of sows

This study evaluated the effects of different gestation housing types on reproductive performance of sows. A total of 60 sows (218 ± 24 kg body weight) with mixed parity were used. During gestation, 28 sows were housed in groups with electronic sow feeders (space allowance = 1.26 m²/sow) and 32 sows were housed in individual stalls (space allowance = 1.20 m²/sow). Sows from both housing types were moved to farrowing crates on day 109 of gestation and stayed until weaning (18 days post‐farrowing). Typical corn‐soybean meal diets were provided to sows during gestation and lactation. Measurements were reproductive performance of sows at farrowing as well as performance of sows and their litter during lactation. Similar total numbers of piglets born at farrowing were observed for sows gestated in both housing types. However, group‐housed gestation sows had more mummies (0.321 vs. 0.064; P < 0.05) and stillbirths (0.893 vs. 0.469; P = 0.073) at farrowing than individual‐housed gestation sows. Consequently, individual‐housing type had higher percentage of piglets born alive (95.5 vs. 90.4%; P < 0.05) than the group‐housing type. Therefore, improved reproductive performance of sows from individual gestating housing was confirmed in this study.     

An assessment of reproductive and lifetime performances of Kagoshima Berkshire gilts and sows

We investigated the reproductive and lifetime performances of Kagoshima Berkshire gilts and sows. We examined 20 605 parity records of 4419 pigs for 2008 to 2012 on a farrow‐to‐finish commercial farm. The mean parity (± SD) of all animals was 3.0 ± 2.1. For farrowing performance, the highest numbers of total pigs born and pigs born alive were found in sows with parities 5 and 6 and with parity 3–6, respectively (P < 0.05). Regarding weaning and mating performance, sows with parity 2 had the lowest preweaning mortality (P < 0.05). The longest weaning‐to‐first‐mating interval was found in parity 1 pigs, and the interval decreased as parity increased (P < 0.05). Parities 0 and 1 pigs had the lowest farrowing rate and those with parity 4 had the highest farrowing rate (P < 0.05). The mean parity at culling, total number of pigs born alive in a lifetime, and nonproductive days in a lifetime were 5.5 ± 2.93, 49.2 ± 24.72 pigs, and 132.1 ± 83.34 days, respectively. These animals had a lower litter size and fertility that the F₁ crossbred sows mainly used in Japan, but a similar tendency for performance by parity.     

Incidence and Prevention of Early Parturition in Sows

A retrospective study, based on 60 990 farrowing records from 35 commercial herds, was performed to determine the incidence of early parturition (<114d) and to investigate the relationship between early parturition and total number of piglets born, number of piglets born alive and percentage of stillborn piglets per litter. The mean gestation length was 115.4 ± 1.62d, and early parturition occurred in 10% of all farrowing records. Sows with early parturition had significantly more stillborn piglets and a larger litter size compared to sows with a normal gestation length (114–117d). Sows with a gestation length <114d were 1.2 times (95% CI: 1.19–1.21; p < 0.001) more likely to have an early parturition at the subsequent parity. A second study was performed in four herds (n = 329) to investigate the efficacy of altrenogest administration on 110–112d (T112) or 111–113d (T113) of gestation for preventing early parturition and to investigate the effect of this treatment on the reproductive performance of sows. The interval between the last altrenogest treatment and the onset of parturition was 3.3 ± 1.32 (T112) or 2.0 ± 0.89 (T113) days. The gestation length of sows of the altrenogest group (T112 + T113) (115.3 ± 1.23d) was significantly longer compared to gestation length of the non‐treated sows (114.7 ± 1.69d) (p < 0.01). Altrenogest treatment had no negative effect on the reproductive performances of the sows. In conclusion, the administration of altrenogest in late gestation is an effective and safe method to prevent early parturition and can counteract the reproductive losses because of premature farrowing, which may occur in a substantial part of the farrowing events.     

Impact of four fiber-rich supplements on nutrient digestibility,colostrum production,and farrowing performance in sows

This study aimed to investigate the impact of dietary fiber (DF) sources on sow and litter performance, and apparent total tract digestibility (ATTD) of gross energy (GE) and nutrients. A total of 48 sows were stratified for body weight at mating and randomly assigned to one of four DF sources (mixed fiber [MF], palm kernel expellers [PKE], sugar beet pulp [SBP], or soy hulls [SH]) and fed the diet from mating until farrowing. Within DF treatments, sows were supplemented with one of two extra energy sources (glycerol or sugar dissolved in water), whereas a third group (control) received water from day 108 of gestation until farrowing. The number of total born, live-born, and stillborn pigs; birth time and birth weight of the pigs; farrowing duration; and farrowing assistance (FA) were recorded. Live-born pigs were weighed again at 12 and 24 h after birth to record weight gain, which was used to estimate intake and yield of colostrum. Blood samples were collected once daily from day −3 relative to farrowing until day 1 after farrowing in sows and once from selected pigs right after birth. Fecal samples were collected on day 114 of gestation and colostrum at 0, 12, 24, and 36 h after onset of farrowing. Intake of soluble and insoluble nonstarch polysaccharides (NSP) was greater for SBP (P < 0.001) and PKE (P < 0.001) supplemented sows, respectively, when compared with other groups. Farrowing duration and stillbirth rate were not affected by DF sources, but PKE and SH supplemented sows had greater FA than SBP and MF supplemented sows (P < 0.001). Extra energy supplement did not improve the farrowing performance. Concentration (P = 0.02) and output (P = 0.04) of dry matter in colostrum, and ATTD of GE (P < 0.001) and crude protein (CP; P < 0.001) were lower for PKE supplemented sows than in sows from the remaining groups. Intake of insoluble NSP correlated negatively with ATTD of GE (P < 0.001) and CP (P < 0.001). Concentrations of glucose (P < 0.001), lactate (P < 0.001), CO₂ (P < 0.001), and HCO₃ (P < 0.001) in sows blood were increased with time progress relative to farrowing. Newborn pigs from PKE supplemented sows had greater concentration of lactate (P = 0.02) and lower blood pH (P = 0.02) than the remaining treatments. In conclusion, PKE supplement reduced ATTD of GE and CP, and concentration and output of dry matter in colostrum but increased FA. Results of this experiment indicated that the use of PKE as a fiber source for late gestating sows should be avoided.     

Comparison of artificial insemination with natural mating on smallholder farms in Thailand,and the effects of boar stimulation and distance of semen delivery on sow reproductive performance

Following the implementation of artificial insemination (AI) services for smallholder pig farms, we investigated the reproductive performance after AI and its influencing factors. A small-scale boar station with an AI lab was established with two active boars having good genetics and free from reproductive diseases. Individual sow cards were used for reproductive data recording. A total of 171 sows on 92 farms situated within a radius of 50 km from the AI center were included in this study. Sows bred by AI (n = 121) were inseminated twice per estrus by two trained inseminators. A further 50 sows were mated by natural services using local rental boars. The impact of boar stimulation and distance from the AI center to the farm were also determined. Non-return (P = 0.02) and farrowing rates (P = 0.03) were higher for AI than for naturally bred sows (84.0% and 76.0% vs. 74.0% and 70.0% for AI and naturally bred, respectively). For sows bred by AI, boar stimulation increased non-return rate (84.1% vs. 70.0%; P = 0.09), farrowing rate (83.7% vs. 69.2%; P = 0.01) and litter size (11.2 ± 2.3 vs. 9.7 ± 1.7; P < 0.01). There was no effect on performance due to distance of semen transport. These results clearly indicate that sow performance on smallholder farms will improve if AI is utilized and boar stimulation is employed.     

Reproductive performance of sows with and without PRRS modified live virus vaccination in PRRS-virus-seropositive herds

Porcine reproductive and respiratory syndrome (PRRS) virus infection causes reproductive failures including return to oestrus, abortion, mummified foetuses, stillborn, and weak-born piglets. The objective of the present study was to investigate reproductive performance of sows in PRRS-virus-seropositive herds with and without PRRS modified live virus (PRRS-MLV) vaccination. The study was conducted in 20 PRRS-virus-seropositive commercial swine herds in Thailand. The data included 211,009 mating and 180,935 farrowing records. The analysed variables included farrowing rate (FR), return rate (RR), abortion rate (AR), total number of piglets born per litter (TB), number of piglets born alive per litter (BA), percentage of stillborn (SB), percentage of mummified foetuses (MM), and number of piglets weaned per litter (WP). The results revealed that FR in non-vaccinated sows was lower than that in vaccinated sows (85.0 vs 89.7 %, respectively, P?<?0.001), and RR in non-vaccinated sows was higher than that in vaccinated sows (6.9 vs 3.7 %, respectively, P?<?0.001). AR did not differ significantly between non-vaccinated and vaccinated sows (1.6 and 2.0 %, respectively, P?=?0.964). TB (11.2 and 11.5, respectively, P?<?0.001), BA (10.0 and 10.6, respectively, P?<?0.001), and WP (9.2 and 9.6, respectively, P?<?0.001) in non-vaccinated sows were lower than those in vaccinated sows. SB (6.9 and 5.1 %, respectively, P?<?0.001) and MM (3.2 and 2.2 %, respectively, P?<?0.001) in PRRS-MLV-vaccinated sows were higher than those in non-vaccinated sows. The improvement in sow reproductive performance in PRRS-MLV-vaccinated herds was most pronounced in gilts and primiparous sows.     

母猪尿路感染的检测方法及应用案例

母猪的尿路感染在种猪场中普遍存在，急性尿路感染会导致母猪猝死，亚临床感染影响母猪繁殖性能。由于缺乏便捷有效的检测方法，尿路感染经常被忽视。文章回顾了母猪尿路感染的原因和感染后的临床表现。为了在现场更好地普及尿路感染检测，文章介绍了一种新型的尿路感染的快速检测方法，并用此方法在山东某规模猪场进行了实际操作，对该场的40份母猪尿液样品进行了检测，分析了该场母猪在分娩前后的尿路感染情况，最后给出了解决方法。     

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.     

Leptin in sow: Influence on the resumption of cycle activity after weaning and on the piglet gain

In sows, a strong relationship exists between body condition and reproductive efficiency and milk yield. Leptin may act as a metabolic gate which permits the activation of reproductive axis: in the sow, serum concentration of leptin was positively correlated with adiposity at farrowing. An interesting aspect useful to clarify the biology of leptin, was the discovery that the placenta expresses the ob gene, the ob receptor gene and it is a site of leptin production, suggesting a possible role of the hormone in fetal growth; after birth, the placenta functions were taken over from milk, especially to the delivery of maternal hormones and growth factors to the neonate. The exact role of maternal leptin in the physiology of neonatal piglets remains to be determined. Our aim was to evaluate if maternal leptin levels at the beginning of lactation and at weaning could predict the resumption of cycle activity and/or the piglet gain. Thirty-eight Large White × Landrace pregnant sows (16 nulliparous and 22 pluriparous) were used. Blood samples were taken from sows and piglets at d 5 and d 21 after farrowing; in the same days, milk samples were taken after oxytocin injection by means of complete manual milking of all mammary glands of one side. On the basis of the blood leptin at d 5, sows were divided into 3 groups (Low: < 2.3 ng/ml; Medium: 2.3 to 2.6 ng/ml; High: > 2.6 ng/ml). Our results show a correlation at d 5 between backfat thickness and blood leptin (r = 0.342; P < 0.05). The resumption of the cyclic activity was faster in sows with a leptin level at d 5 greater than 2.3 ng/ml (P < 0.01). Milk composition at d 5 and 21 was not affected by parity and leptin. Piglet ADG was significantly (P < 0.05) influenced by sow leptin groups (0.180 kg day^− 1 for piglets from Low group and 0.224 for High group). Piglets weaned by High group sows have shown a greater blood leptin content at weaning (P < 0.01) than other groups. In conclusion we have found a significant correlation between leptin and productive and reproductive performances of pigs. This paper underlines the pleiotropic actions exerted by leptin in the productive sow.     

Reproductive Performance of Purebred Swedish Landrace and Swedish Yorkshire Sows: II. Effect of Mating Type,Weaning-to-first-service Interval and Lactation Length

The objective of this retrospective study was to investigate the effect of mating type [natural mating (NM) versus artificial insemination (AI)], weaning-to-first-service interval (WSI) and lactation length on some reproductive traits of purebred Swedish Landrace (L) and Swedish Yorkshire (Y) sows. Data analysed comprised farrowings during the period 1994-1997 from 19 Swedish nucleus herds and included 20 275 litters from 6989 purebred sows (3598 L and 3391 Y). Analysis of variance was used for the statistical analysis of quantitative data. Logistic regression analysis was applied for binary data using the GLIMMIX macro in the SAS program. The response variables analysed were litter size, WSI, farrowing rate and remating rate. Explanatory variables included in the analyses were mating type, lactation length, sow breed, boar breed, parity, herd-year combination within breed and month of the year. The effect of WSI on subsequent fertility performance (i.e. litter size, farrowing rate and remating rate) was also analysed. Compared with AI, NM resulted in significantly larger litters (0.2 total born per litter; P<0.001; 0.3 born alive per litter; P<0.001), and lower remating rate (1.6%-units; P<0.01). The difference between NM and AI varied according to sow breed, parity number and month of the year. Subsequent litter sizes decreased by about one piglet when WSI increased from 4 to 10 days. Thereafter, litter size increased as the WSI increased from 10 to 20 days. Farrowing rate decreased gradually when WSI increased from 4 to 7 days, but an increase in WSI from day 9 to day 20 resulted in an increase in farrowing rate. A longer lactation period led to a shorter WSI and a larger subsequent litter size for both breeds.     

Season-dependent effect of daily frequency of feed distribution on the rate of feed consumption and reproductive performance in sows during lactation

The effects of the daily frequency of feed distribution (once, One; twice, Two; and four times, Four,) on the rate of feed consumption (RFC) and reproductive performance were investigated in Large White sows farrowing in the hot season from June to September (H sows) and in the rest of the year (R sows). The RFC was greater in feeding treatment Four than Two (P < 0.01) in H sows; however, bodyweight loss during lactation was not affected by the feeding treatment. No difference in effects of frequency of feed distribution for sows was observed on piglet growth. The survival rate of the piglets was not different between feeding treatments. The number of sows that came into estrus within 7 days post‐weaning was smaller in the feeding treatment Four than One (P < 0.05) in H sows and those of Four than One (P < 0.01) and Two (P < 0.05) in R sows. These results suggest that in sows during lactation increasing the daily frequency of feed distribution may have a negative effect on reproductive performance.     

Effect of farrowing duration, parity number and the type of anti-inflammatory drug on postparturient disorders in sows: a clinical study

The aim of the present study was to investigate the effects of farrowing duration, parity number, and type of anti-inflammatory drug used postpartum on the incidence of postparturient disorders in sows. The duration of farrowing and postparturient disorders were examined in 64 sows at Days 0, 1, 2, and 3 after farrowing. The sows were classified according to parity number (1, 2–4, and 5–7), duration of farrowing (<2, 2–2.9, 3–3.9, and 4–8 h), and the type of anti-inflammatory drugs (flunixin méglumine and dipyrone). The farrowing duration was 178.0?±?73.5 min (2.96 h). The percentage of sows with fever increased from 40 to 100 % when the farrowing duration increased from <2 to 4–8 h. On Day 1 of the postpartum, 93.7 % of primiparous sows had fever, while 52.6 and 47.6 % of sows parity 2–4 and 5–7 had a fever (P?<?0.05). The presence of vaginal discharge on Day 1 of the postpartum was higher in sows of parity 5–7 than sows of parity 2–4 (85.7 and 52.6 %, P?=?0.029). The use of flunixin méglumine after parturition in sows reduced the percentage of sows with a fever from 61.3 to 22.6 % within 2 days (P?=?0.002), while, the percentage of sows with a fever was not decreased in sows treated with dipyrone. It can be concluded that the incidence of postparturient disorders in sows was affected by sow parity, farrowing duration and the type of anti-inflammatory drug used. Sows with a farrowing duration of ≥4 h were at a high risk of having fever at Day 1 after parturition.     

Effects of L‐citrulline supplementation on heat stress physiology,lactation performance and subsequent reproductive performance of sows in summer

Lactating sows are susceptible to heat stress (HS). Part of the thermoregulatory response to HS is to increase peripheral blood flow, which is mediated in part by the vasodilator, nitric oxide (NO). Therefore, the aim of this experiment was to determine the effect of supplementation of L‐citrulline, a NO precursor, on symptoms of HS, lactation performance and subsequent reproductive performance of sows in summer. A total of 221 summer farrowing mixed parity sows were fed either a control diet or supplemented with 1% L‐citrulline upon entry to the farrowing house (6 ± 1.8 days for mean ± standard deviation [SD] before farrowing) until weaning (26 ± 1.5 days). The average daily minimum and maximum temperature in the farrowing house was 21.0 ± 1.88 and 29.2 ± 3.82°C (mean ± SD). Rectal temperature, respiration rate, and plasma and urinary nitrite and nitrate (NOx) of sows were measured on the 19th day post‐farrowing. Supplemental L‐citrulline in the diet did not affect the number of piglets born alive, feed intake of sows, body weight or backfat thickness of sows at weaning, or litter weight gain. L‐citrulline tended to reduce piglet pre‐weaning mortality rate from 18.6% to 15.6% (p = 0.058). L‐citrulline reduced the respiration rate of sows compared to the control diet at 17:00 hr (Time × Diet, p < 0.001); however, rectal temperature was not affected. L‐citrulline tended to increase urinary NOx concentrations (127 vs. 224 µM, p = 0.057) but not plasma NOx concentrations. L‐citrulline did not affect farrowing rate or number of piglets born alive in the subsequent parity. In conclusion, L‐citrulline supplementation reduced respiration rate of lactating sows and reduced piglet pre‐weaning mortality rate in summer. Whether the effects were due to a NO‐dependent mechanism requires further validation.     

Salmonella in sows: a longitudinal study in farrow-to-finish pig herds

Besides finishing pigs, sows are also believed to be important in the epidemiology of Salmonella. The study objective was to investigate the prevalence of Salmonella excretion in sows during an entire reproductive cycle. In 3 farrow-to-finish herds, groups of 34, 40 and 32 sows, respectively, were sampled serially. Faecal samples, environmental swabs and feed samples were taken and submitted to a qualitative Salmonella isolation. All isolates were characterised using RAPD and a representative number of isolates was serotyped. The prevalence of Salmonella excretion was < 10% during gestation, around farrowing and during lactation, but a significant increase in the number of Salmonella excreting sows was found in herds A (p < 0.01) and C (p = 0.02) after weaning. S. Infantis was the most prevalent serotype in herd A, S. Derby in herds B and C. Except for the S. Infantis group in herd A, all isolates within each group of the RAPD analysis belonged to the same serotype. Three sows in herd A and 1 sow in herd C shed different serotypes at different time points. The present results indicate that sows can maintain Salmonella infections in farrow-to-finish herds and that culled sows, leaving the herd after weaning, may constitute a substantial risk for contamination of their carcasses with Salmonella.     

Control of the weaning-to-estrus interval in sows using gonadotropins and prostaglandins during lactation.

Two experiments were conducted to examine the effectiveness of various strategies using gonadotropins to induce ovulation during lactation as a means of controlling the weaning-to-estrus interval in sows. The objective of Exp. 1 was to examine the efficacy of various gonadotropin regimens for induction of ovulation during lactation. Primiparous (n = 60) and multiparous (n = 83) crossbred sows were assigned, before farrowing, to one of four treatments: no injection (control); 1,000 IU hCG on d 0 (hCG-0; d 0 = day of farrowing); P.G. 600 + 1,000 IU hCG 4 and 7 d after farrowing, respectively (hCG-7); or P.G. 600 + 1,000 IU hCG 11 and 14 d after farrowing, respectively (hCG-14). Sows were weaned on 18 +/- 2 d after farrowing and monitored daily for estrus via exposure to mature boars. The criterion for determining the induction of ovulation was a sustained increase in serum progesterone concentrations above 4.0 ng/mL. The most consistent response to exogenous gonadotropins was on d 0, with an 80% response in primiparous sows (12/15) and a 71% response in multiparous sows (15/21). Weaning-to-estrus intervals for multiparous sows were longer (P = .05) for hCG-14 and hCG-7 than for control and hCG-0 sows. Weaning-to-estrus intervals for primiparous sows were longer (P = .05) for the hCG-14 than for the hCG-0 treatment. The objective of Exp. 2 was to ascertain the effects of postpartum treatment with hCG (1,000 IU) on d 0 and PGF2alpha (10 mg) at d 14 on the weaning-to-estrus interval in multiparous sows weaned at d 14 after birth. Before farrowing, sows (n = 60) were randomly assigned to one of four treatments: positive control, weaning at d 21; negative control, weaning at d 14; hCG within 24 h after farrowing, weaning at d 14; or hCG within 24 h after farrowing and PGF2alpha at weaning, weaning at d 14. Weaning-to-estrus intervals were longer (P = .05) in sows receiving PGF2alpha than in the other treatments. Results indicate that it is possible to induce ovulation immediately after farrowing, using a single injection of hCG, and this strategy can be used to uncouple weaning from the resumption of reproductive activity. However, the administration of PGF2alpha at 14 d after farrowing did not consistently cause regression of the induced corpora lutea.     

Isomaltooligosaccharide and Bacillus regulate the duration of farrowing and weaning-estrous interval in sows during the perinatal period by changing the gut microbiota of sows

This study investigated the effects of isomaltooligosaccharide (IMO) and Bacillus in perinatal diets on the duration of farrowing and post-weaning estrus, serum reproductive hormone concentrations, and gut microbiota and its metabolites of sows. Multiparous sows (n = 130) were fed diets without IMO (control, CON group), or diets containing only IMO (IMO group), IMO and Bacillus subtilis (IMOS group), IMO and Bacillus licheniformis (IMOL group), and IMO and B. subtilis and B. licheniformis (IMOSL group), respectively. The results indicate that the duration of farrowing and post-weaning estrus was shorter in sows in the IMOS, IMOL, and IMOSL groups, and the weaning-estrous interval was lower in sows in the IMOL greoup. In addition, the lowest fecal score was observed in the IMOL group during d 106 to 112 of gestation. Sows in most of the treatment groups had a higher concentration of serum prolactin and prostaglandin at farrowing, but a lower serum concentration of estradiol, oxytocin, and progesterone on d 18 of lactation than sows in the CON group. The treatment groups had a higher abundance of Candidatus Methanoplasma and Bacillus and a lower abundance of Escherichia-Shigella in their feces at farrowing. Furthermore, the treatment groups had higher concentrations of total short-chain fatty acids (SCFA) in feces at farrowing and a higher concentration of branched fatty acids in feces on d 18 of lactation. Furthermore, the abundance of Bacillus in feces was positively correlated with serum prostaglandin concentrations and fecal total SCFA of sows at farrowing, but was negatively correlated with the duration of farrowing. Overall, dietary IMO and Bacillus supplementation affected the concentration of serum reproductive hormones and the duration of farrowing and post-weaning estrus, and the gut microbiota is a key factor.