Dietary CP and digestion kinetics influence BW loss, litter weight gain, and reproduction by affecting postprandial amino acid metabolism in lactating sows.

To avoid a high body protein mobilization in modern lean sows during lactation, an adequate dietary amino acid (AA) supply and an efficient AA utilization are crucial. This study evaluated the effects of dietary CP and in vitro protein digestion kinetics on changes in sow body condition, litter weight gain, milk composition, blood metabolites, protein utilization efficiency and subsequent reproductive performance. We hypothesized that a slower digestion of dietary protein would improve AA availability and utilization. In total, 110 multiparous sows were fed one of four lactation diets in a 2 × 2 factorial design, with two CP concentrations: 140 g/kg vs 180 g/kg, and two protein digestion kinetics, expressed as a percentage of slow protein (in vitro degradation between 30 and 240 min): 8 vs 16% of total protein. Feeding sows the high CP diets reduced sow weight loss (Δ = 7.6 kg, P < 0.01), estimated body fat loss (Δ = 2.6 kg, P = 0.02), and estimated body protein loss (Δ = 1.0 kg, P = 0.08), but only at a high percentage of slow protein. A higher percentage of slow protein increased litter weight gain throughout lactation (Δ = 2.6 kg, P = 0.04) regardless of CP concentrations, whereas a higher CP only increased litter weight gain during week 3 of lactation (Δ = 1.2 kg, P = 0.01). On Day 15 postfarrowing, serial blood samples were taken from a subsample of sows fed with the high CP diets. In these sows, a high percentage of slow protein resulted in higher plasma AA concentrations at 150 and 180 min after feeding (Δ = 0.89, P = 0.02, Δ = 0.78, P = 0.03, mmol/L, respectively) and lower increases in urea at 90 and 120 min after feeding (Δ = 0.67, P = 0.04, Δ = 0.70, P = 0.03, mmol/L, respectively). The higher dietary CP concentration increased total nitrogen loss to the environment (Δ = 604 g, P < 0.01) with a reduction of protein efficiency (Δ = 14.8%, P < 0.01). In the next farrowing, a higher percentage of slow protein increased subsequent liveborn litter size (Δ = 0.7, P < 0.05). In conclusion, feeding sows with a high dietary CP concentration alleviated maternal weight loss during lactation when the dietary protein digestion rate was slower, but lowered protein efficiency. A slower protein digestion improved litter weight gain, possibly by reducing AA oxidation and improving plasma AA availability, thus, improving protein efficiency.

Physiology and management of the peri-parturient sow in the context of changing production conditions.

Genetic selection has resulted in a considerable increase in litter size, paralleled by an increase in farrowing duration and perinatal mortality. This paper describes some of the physiological changes around farrowing, and how genetic trends and sow management interact with these. Compromised farrowing can be related to nutritional management, or to housing conditions and handling of periparturient sows. Transition diets, for example, can be formulated to support calcium homeostasis and alleviate constipation. The opportunity to express natural behaviours and minimize stress around farrowing can further optimize farrowing conditions and reduce piglet mortality. Loose farrowing systems are part of the answer to the challenges around farrowing; however, current systems do not perform consistently. In conclusion, increased farrowing duration and increased perinatal mortality may to some extent be inevitably related to trends in pig production; however, they can be improved by nutritional measures, housing conditions and farrowing management.

Review: Targeted nutrition in gestating sows: opportunities to enhance sow performance and piglet vitality.

Birth weight is a key factor for piglet survival, and therefore, there is ongoing interest in how nutrition during gestation can influence birth weight. Interestingly, sows are generally fed one single diet throughout gestation. This paper reviews past attempts to increase foetal growth to term and discusses opportunities to target nutritional manipulations at specific windows of gestation where key developmental events occur. Birth weight limits chances to survive mainly in piglets with birth weight below 1 kg. These piglets represent around 16% of the population. Given the normal distribution of birth weight, the mean birth weight needs to be increased by at least 50-100 g to have a meaningful impact on this proportion of the population and on perinatal survival. Based on existing variation in reported mean birth weight across a number of studies, it is argued that it is unrealistic to expect an increase in mean birth weight of more than 100 g. Attempts in the past to increase birth weight have focussed on the last trimester of gestation, when foetal growth is accelerated. Increase in feed allowance or nutritional concepts that target placenta vascularisation have not been successful. It is argued that nutritional manipulations should rather focus on the middle of gestation, since in that period, placenta growth occurs and since placenta size limits the foetal size. Alternatively, nutritional manipulations can target placentation during the embryonic phase.

Effect of low colostrum intake on gastrointestinal development and uterine and cervical morphometrical architecture in the neonatal gilt.

To assess the importance of natural variation in colostrum intake on piglet gastrointestinal and reproductive development, two equally sized female piglets from each of 27 litters were selected, one with low (average 226 g) and one with high (average 401 g) colostrum intake. At weaning (23 d of age), piglets were euthanised to perform macromorphological measurements on ileum, colon, cervix and uterus tissues, and to obtain tissue samples from the cervix and uterus for histology. Sections of uterine and cervical preparations were analysed using digital image analysis. Despite being selected for the same birth weight (average 1.1 kg, standard deviation 0.18 kg), piglets with low colostrum intake weighed 5.91 ± 0.17 kg and piglets with high colostrum intake weighed 6.96 ± 0.19 kg at weaning (P < 0.05). Most of the micro- and macroscopic measures such as length and weight of ileum and colon, cervix and uterus, luminal size of cervix and uterus, number of cervical crypts and uterine glands, were greater in gilts with high colostrum intake. The histological architecture of the uterus and cervix in gilts with high colostrum intake showed more complexity, reflecting more advanced development in these piglets. In conclusion, these data demonstrate that independent of birth weight, natural variation in colostrum intake is related to the overall development of neonatal piglets, affecting body growth, as well as growth and development of the gut and reproductive tract.

Single pharmacy governed denosumab home administration: optimal adherence by means of a fracture liaison service (FLS) and home care collaboration.

Low adherence for denosumab (Dmab, Prolia®) is of major concern. Dutch pharmacies deliveries were calculated recently being 76.5% for a total of 3 injections. INTRODUCTION: Comparing a model where the prescriber maintains responsibility for adherence (model HC1) (Dmab is purchased and dispensed by patient's own community pharmacy and administered through a home care service (HC)) or an all-in-one model where the pharmacist maintains responsibility for the adherence (Dmab is purchased, dispensed, and administered by a pharmacist's HC) (HC2). METHODS: We counted the number of Dmab injections, follow-up appointments on time, Dmab administrations delayed to a maximum of 60 days, the number of Dmab discontinuations, and all causes legally traceable under EU privacy act (EDPR). RESULTS: Home care started by 2014 (study closure in 2021) and included 711 Dmab injections to 256 unique patients: HC1: 536 and HC2: 175 orders. The whole group received on average 2.8 Dmab injections by consistent intervals of about 182 days. Average administration after the latest Dmab injection: 272.8 days (HC1: 362.0 and HC2: 124.0 days). Administration of a subsequent injection > 60 days occurred in 26.6% (HC1: 38.8% and HC2: 6.2%; OR = 9.49). After adjustment for no more than three Dmab injections administered per patient, it occurred in 27.3% (HC1: 51.8% and HC2 4.4%; OR = 23.34). CONCLUSION: It was possible to achieve 94% adherence for Dmab injections treatment just by transferring the complete supply chain to one pharmacy-initiated home care provider after treatment initiation by either a physician or FLS health care professional.

Lactational oestrus and reproductive performance following a delayed limited nursing schedule in primiparous sows.

With conventional lactation management, sows only conceive after weaning. However, intermittent suckling (IS) enables follicle growth and ovulation during lactation by reducing the suckling-induced inhibition of gonadotrophins. The current study evaluated IS regimes initiated at Day 21 or Day 28 post farrowing compared to conventional weaning on Day 28, in primiparous sows. Sows (Large White and Large White x Landrace) were randomly allocated to Control (C28; n = 44), IS21 (n = 29) and IS28 (n = 34) treatments at Day 20. Sows in IS21 and IS28 were subjected to intermittent suckling from Day 21 or Day 28 post farrowing. During IS, sows were separated from their piglets for 8 h daily, then weaned 7 d later at Day 28 and Day 35 respectively, whereas piglets in the C28 treatment had continuous access to sows until weaning at Day 28. Percentage of IS sows that showed oestrus during lactation was 59% (16/27) in IS21 and 72% (21/29) in IS28 (P > 0.05). Cumulatively over the lactation and 7 d post-weaning period, 93% of IS21, 85% of IS28 and 93% (31/33) of C28 sows showed oestrus (P > 0.05). Pregnancy rate at Day 30 post mating, for sows that were mated during lactation was 93% (15/16) in IS21 and 95% (20/21) in IS28, whereas C28 sows had a 96% (30/31) pregnancy rate (P > 0.05). No difference was found in the time of oestrus relative to weaning (C28) or onset of IS (IS21 and IS28) (P > 0.05). The IS sows that did not ovulate before weaning all showed oestrus within 7 days from weaning, and the weaning to oestrus interval was similar to control sows (P > 0.05). However, for all IS sows (across IS treatments) that showed lactational ovulation, LH secretion pattern at onset of IS was different (P < 0.05) from the sows that did not ovulate in lactation. Plasma progesterone concentration tended to be lower in the IS21 treatment (P < 0.10) compared to the C28 sows at 4 d after ovulation. The subsequent litter size was not affected by treatments although numerically lower for IS21 (P > 0.05). The present study showed that in modern primiparous sows, lactational oestrus can be induced and pregnancy can be maintained at a similar rate and producing comparable subsequent litter sizes to conventionally weaned sows when IS commenced at four weeks post farrowing. However, when IS commences at three weeks post farrowing, this may affect the percentage of sows showing oestrus in lactation and may potentially influence subsequent litter size.

Temporary undernutrition during early gestation, corpora lutea morphometrics, ovarian progesterone secretion and embryo survival in gilts.

The present study reports effects of severe undernutrition on luteal function and pregnancy in pigs. Gilts were inseminated and either fasted on Day 10 and 11 after conception (n=11) or fully fed throughout (n=10). Fasting did not affect LH or progesterone pulsatile secretion pattern on Day 11 in samples taken from blood vessels draining an ovary. Ultrasonographic measurements of the size of the corpora lutea did not show any effect of fasting either. However, fasted gilts had 10 to 30% lower systemic progesterone from Day 12 through Day 15 after conception (P<0.05). All gilts farrowed, but fasted gilts had fewer born piglets than fully fed gilts (8.8±0.8 vs 10.9±0.5 respectively; P<0.05). In conclusion, fasting during embryo elongation can compromise embryonic survival by affecting ovarian function in the days after fasting, without having an immediate effect on LH secretion and progesterone output by the ovaries.

Elevating glucose and insulin secretion by carbohydrate formulation diets in late lactation to improve post-weaning fertility in primiparous sows.

Primiparous (P1) sows commonly lose excessive body reserves to meet energy requirements for maintenance and milk production during lactation, and consequently, post-weaning reproductive performance may be compromised. The present studies determined whether ad libitum feeding a glucogenic carbohydrate diet (CHO) during late lactation could stimulate insulin and glucose secretion (experiment 1) and improve subsequent litter size (experiment 2). For experiment 1, 15 P1 sows, and for experiment 2, 99 P1 sows (198.5 ± 2.7 kg) were allocated randomly according to suckled litter size (≥10 piglets), either to a CHO diet (14.3 MJ DE/kg, 19.8% crude protein) or a standard lactation diet (control; 14.2 DE MJ/kg, 19.5% crude protein) at 8 days before weaning. The CHO diet aimed to provide glucogenic content (extruded wheat, dextrose and sugar) as energy sources instead of fat sources without changing total dietary energy. Pre-prandial plasma glucose and insulin concentrations were not influenced by treatments. However, post-prandial plasma glucose and insulin concentrations and their peaks were both higher (p < .05) compared to the control treatment. Body weight loss during lactation was relatively low at 3%-4% for both treatments and did not differ between control and CHO treatments (-7.6 ± 1.6 vs -5.4 ± 1.2 kg; p > .05). Second litter size was not influenced by diet (p > .05), but the weaning-to-mating interval was shorter in CHO sows (p < .05). This study demonstrates that providing an enriched CHO diet in late lactation did influence post-weaning follicle growth but did not improve subsequent litter size. This may be due to the primiparous sows in this study not experiencing severe negative energy balance and there was no second litter syndrome in this farm which limited the ability of diet to improve sow fertility.

Human chorionic gonadotrophin in early gestation induces growth of estrogenic ovarian follicles and improves primiparous sow fertility during summer.

Reduced summer farrowing rates may be due to inadequate corpora luteal (CL) support. Porcine CL become dependent on LH from 12 d of pregnancy and the embryonic estrogen signal for maternal recognition of pregnancy (MRP) is initiated at about 11-12 d after insemination. We hypothesised that injection of the LH analogue human chorionic gonadotropin (hCG) would induce growth of estrogenic follicles and, by mimicking the signal for MRP and stimulating progesterone secretion, increase primiparous sow fertility. In Experiment 1, during a 28 d lactation 53 mixed parity sows were full-fed either throughout lactation (n=16) or until 18 d and then feed restricted during the last 10 d of lactation (n=36). At 12 d after mating restrict-fed sows were injected with 1000IU hCG (n=17) or were not injected (n=19); the full-fed sows acted as non-treated positive controls. Transrectal ovarian ultrasound exams were performed on days 12, 16, 20, 24, and 28; blood samples were obtained on days 12, 14, and 15 for estradiol and progesterone assay. For Experiment 2, during the summer months primiparous sows received 1000IU hCG 12 d after mating (n=28) or were non-injected controls (n=27). Pregnancy status was determined at 28 d and sows allowed to go to term to determine farrowing rates and litter sizes. In Experiment 1, injection of hCG increased (P<0.001) follicle diameter and serum concentrations of estradiol (P<0.01) and progesterone (P<0.05). There were no effects of lactation feeding level on wean-estrus interval, farrowing rate or subsequent litter size. In Experiment 2, hCG injection was associated with a higher pregnancy rate (P<0.05) and farrowing rate (P<0.08). There was no effect on litter size. These data confirm that hCG stimulates growth of estrogenic follicles and CL function, and improves primiparous sow fertility during the summer months.

Embryonic survival at day 9, 21 and 35 of pregnancy in intact and unilaterally oviduct ligated multiparous sows.

To investigate the effect of uterine space on timing of embryonic mortality, multiparous sows were left intact (CTR; n=42) or subjected to unilateral oviduct ligation (LIG; n=23), after their first post wean oestrus. Intact sows were killed at day 9 (n=10), day 21 (n=15), or day 35 (n=17), and LIG sows were killed at day 21 (n=11) or day 35 (n=12) of gestation. At day 9, 92% of ovulations were represented by an embryo. At day 21, embryonic mortality was 24% and was not altered by increasing uterine space. At day 35, space per embryo was twice as large in LIG sows (30±3 v. 16±0.8 cm), and implantation length tended to be larger (19.0±1.2 v. 15.5±1.3 cm). Between day 21 and day 35, CTR sows lost another 8% to 14% of their embryos, whereas LIG sows lost none. Embryos tended to be heavier (4.9±0.2 v. 4.3±0.3 g) in LIG sows. In conclusion, embryonic loss in multiparous sows is 24% by day 21 and is not related to space, whereas after day 21 limited space causes additional 8% to 14% embryonic mortality in intact sows only.

No effect of the infiltration of local anaesthetic for total hip arthroplasty using an anterior approach: a randomised placebo controlled trial.

Only limited data are available regarding the infiltration of local anaesthetic for total hip arthroplasty (THA), and no studies were performed for THA using the anterior approach. In this prospective, randomised placebo-controlled study we investigated the effect of both standard and reverse infiltration of local anaesthetic in combination with the anterior approach for THA. The primary endpoint was the mean numeric rating score for pain four hours post-operatively. In addition, we recorded the length of hospital stay, the operating time, the destination of the patient at discharge, the use of pain medication, the occurrence of side effects and pain scores at various times post-operatively. Between November 2012 and January 2014, 75 patients were included in the study. They were randomised into three groups: standard infiltration of local anaesthetic, reversed infiltration of local anaesthetic, and placebo. There was no difference in mean numeric rating score for pain four hours post-operatively (p = 0.87). There were significantly more side effects at one and eight hours post-operatively in the placebo group (p = 0.02; p = 0.03), but this did not influence the mobilisation of the patients. There were no differences in all other outcomes between the groups. We found no clinically relevant effect when the infiltration of local anaesthetic with ropivacaine and epinephrine was used in a multimodal pain protocol for THA using the anterior approach.

Cystic ovaries in intermittently-suckled sows: follicle growth and endocrine profiles.

This paper presents follicle development and hormone profiles for sows with normal ovulation or cystic follicles during an intermittent-suckling (IS) regime that started at Day 14 of lactation. Sows were subjected to separation from their piglets during blocks of 6h or 12h. In total, 8 out of 52 sows developed cystic follicles; either full cystic ovaries (n=6) or partial ovulation (n=2). Increase in follicle size of these sows was similar to that of normal ovulating sows until pre-ovulatory size at Day 5 after the start of separation, but from then on became larger (P<0.05). LH surge was smaller or absent in sows that developed (partially) cystic ovaries (0.4 ± 0.1 vs 3.6 ± 0.3 ngmL(-1); P<0.01). Peak levels of oestradiol (E2) were similar but high E2 levels persisted in sows that developed (partly) cystic ovaries and duration of oestrus tended to be longer. The risk of developing (partly) cystic ovaries was higher when IS occurred in blocks of 6h versus 12h (33 vs 10%). In conclusion, the appearance of cystic ovaries at approximately Day 20 of ongoing lactation was related to an insufficient LH surge, as is also the case in non-lactating sows.

Effect of feeding level on luteal function and progesterone concentration in the vena cava during early pregnancy in gilts.

This study assessed the effect of feeding level on progesterone concentration in the caudal vena cava during early pregnancy in gilts. Twenty-four Landrace gilts were allocated to either a high (2.8±0.02) or a low (1.5±0.01 kg day⁻¹) feeding level at Day 0 of pregnancy. Serial blood samples were collected every 15 min for 3 h before and 3 h after feeding on Days 6 and 9 of pregnancy. Embryo survival and development as well as in vitro luteal progesterone production were assessed at Day 10 of pregnancy. Progesterone concentration in the vena cava was pulsatile with gilts on the high feeding level having more pulses compared with Low gilts on Day 9 of pregnancy (P<0.05). On Day 6 the number of pulses did not differ significantly between treatments; however, the average progesterone concentration in the vena cava tended to be higher in the gilts on the high feeding level (P<0.10). Embryo survival at Day 10 was 92±3% for High gilts compared with 77±3% for Low gilts (P<0.05). No difference in embryo development between the treatments was seen. There was no difference between treatments in in vitro secretion of progesterone by luteal tissue. In conclusion, a high plane of nutrition positively affects progesterone secretion by the ovaries in early pregnancy.

Effects of pre-weaning dietary substitutions on plasma insulin and glucose profiles in primiparous sows.

The objective of this study was to investigate the effects of substituting 1 kg of a standard lactation diet with 1 kg of a sugar-rich (15.75 DE MJ/kg) or fat-rich (23.85 DE MJ/kg) diet during late lactation on blood glucose and insulin changes in primiparous sows. During a 4-week lactation period, 21 primiparous sows were fed to appetite with a standard lactation diet (14.10 DE MJ/kg). At 9 days before weaning, sows were assigned to a control (C, n = 7), fat (F, n = 6) or sugar (S, n = 8) treatment. During the treatment period (from 8 days before weaning until weaning), 1 kg of the lactation diet was substituted with 1 kg of a sugar-rich or fat-rich diet for S and F sows. At 3 days before weaning, serial blood samples were collected for a total of 228 min around feeding to establish pre- and postprandial plasma glucose and insulin concentrations. Preprandial plasma glucose and insulin concentrations did not differ between treatments (p > 0.05); however, mean plasma glucose and insulin concentrations were higher for S compared to F (p < 0.05) and intermediate for the C sows. Postprandial plasma concentrations of glucose and insulin were higher for the S sows than for C and F sows (p < 0.05). Sow body weight loss during late lactation did not differ between treatments (p > 0.05). The results from our study suggest that a sugar-enriched diet during the last week of lactation elevates circulating glucose and insulin concentrations and may potentially improve post-weaning fertility in primiparous sows.

Effects of pre-weaning energy substitutions on post-weaning follicle development, steroid hormones and subsequent litter size in primiparous sows.

The present study investigated the effects of pre-weaning energy substitutions on follicular development, endocrine characteristics and subsequent litter size in primiparous sows. Sows were fed a standard lactation diet (14.1 DE MJ/kg) and then allocated to a Control (C, n = 24), Fat (F, n = 23), Sugar (S, n = 23) or post-weaning Regumate (positive control; R, n = 22) treatment at 9 days before weaning of the C, F and S treatments. During the treatment period (8 days), 1 kg of the lactation diet was substituted with 1 kg of a fat-rich (F, 23.85 DE MJ/kg) or sugar-rich (S, 15.75 DE MJ/kg) substitution for F and S sows, respectively. For the R treatment, sows were weaned 8 days earlier than other treatments and fed a lactation diet at 3.5 kg with two doses of altrenogest as topdressing from 1 day before weaning until the day on which the other sows were weaned. The F treatment aimed to increase energy intake, and the S treatment aimed to elevate post-prandial glucose and insulin concentrations. Weaning-to-ovulation interval tended to be reduced in the S treatment compared with C (p = 0.06) and F (p = 0.08) treatments. Body weight (BW) loss during the treatment period, post-weaning follicle development, plasma oestradiol and pre-weaning leptin did not differ among C, F and S sows, although BW loss was lower and leptin was higher in the R treatment. Post-ovulatory progesterone concentration in the S treatment was higher (p < 0.05). Sows in the S and R treatments had a greater proportion of litters with larger litter sizes (p < 0.05). The outcome suggests that increasing circulating insulin and glucose concentrations during late lactation or a week of metabolic recovery positively improves subsequent litter size in primiparous sows.

Undernutrition during early follicle development has irreversible effects on ovulation rate and embryos.

This study assessed carry-over effects of energy level during the early antral phase and subsequent follicular phase on follicle recruitment and ovulation rate. Gilts (n=45) were fed a standard diet to a low (L, ~1.2kg day(-1)) or high (H, ~2.7kg day(-1)) level during the early antral (luteal) phase, and subsequently fed a H or L feed level during the follicular phase, resulting in four treatment groups (HH, HL, LH and LL). Follicle size at the end of the luteal phase was greater for gilts fed a high feed level previously (3.3vs3.0mm; P<0.05). During the follicular phase, high feeding increased follicle size at Day 5 (6.9vs6.2mm; P<0.005) and plasma oestradiol concentration (P<0.05). Nevertheless, a low feed level during the luteal phase reduced ovulation rate (14.4vs13.2; P<0.05) and embryo number (12.6vs10.5; P<0.05), and this was not counteracted by feed level during the follicular phase. Plasma progesterone concentration after ovulation was lower for LL gilts than for other treatments (P<0.05). These results indicate that undernutrition during early antral follicle development may have a residual effect on follicle recruitment and quality.

Progestagen supplementation during early pregnancy does not improve embryo survival in pigs.

Progesterone supplementation during early pregnancy may increase embryo survival in pigs. The current study evaluated whether oral supplementation with an analogue of progesterone, altrenogest (ALT), affects embryo survival. A first experiment evaluated the effect of a daily 20-mg dosage of ALT during days 1-4 or 2-4 after onset of oestrus on embryo survival at day 42 of pregnancy. A control group (CTR1) was not treated. The time of ovulation was estimated by transrectal ultrasound at 12-h intervals. Altrenogest treatment significantly reduced pregnancy rate when start of treatment was before or at ovulation: 25% (5/20) compared to later start of treatment [85% (28/33)] and non-treated CTR1 [100% (23/23)]. Altrenogest treatment also reduced (p < 0.05) number of foetuses, from 14.6 ± 2.6 in CTR1 to 12.5 ± 2.5 when ALT started 1-1.5 days from ovulation and 10.7 ± 2.9 when ALT started 0-0.5 days from ovulation. In a second experiment, sows with a weaning-to-oestrous interval (WOI) of 6, 7 or 8-14 days were given ALT [either 20 mg (ALT20; n = 49) or 10 mg (ALT10; n = 48)] at day 4 and day 6 after onset of oestrus or were not treated (CTR2; n = 49), and farrowing rate and litter size were evaluated. Weaning-to-oestrous interval did not affect farrowing rate or litter size. ALT did not affect farrowing rate (86% vs 90% in CTR2), but ALT20 tended to have a lower litter size compared with CTR2 (11.7 ± 4.1 vs 13.3 ± 3.1; p = 0.07) and ALT10 was intermediate (12.3 ± 2.9). In conclusion, altrenogest supplementation too soon after ovulation reduces fertilization rate and embryo survival rate and altrenogest supplementation at 4-6 days of pregnancy reduces litter size. As a consequence, altrenogest supplementation during early pregnancy may reduce both farrowing rate and litter size and cannot be applied at this stage in practice as a remedy against low litter size.

Timing of lactational oestrus in intermittent suckling regimes: consequences for sow fertility.

Three intermittent suckling (IS) regimes were evaluated for their effects on lactational oestrus and subsequent fertility. Control sows were weaned (CW; n = 38) at d 26 ± 2 of lactation. In IS19-7D (n=40) and IS19-14D (n=42) sows, IS started at d 19 ± 1 of lactation and sows were weaned 7 or 14 d later. In IS26-7D (n=41), IS started at d 26 ± 1 of lactation and sows were weaned 7d later. During IS, sows were separated from their piglets for 10h/day. Oestrus detection was performed twice daily without a boar and ovulation was confirmed by ultrasound once a week. In IS19-7D, IS19-14D and IS26-7D, respectively, 50%, 64% and 61% of the sows showed oestrus and ovulation during IS (P>0.05), and, of the remaining sows, 100%, 93%, and 69% showed oestrus in the first week after weaning. In CW sows, 95% showed oestrus in the first week after weaning. Parity 1 sows were considerably less likely than older parities (23% vs. 68%) to show oestrus in lactation. Pregnancy rate of the first post partum oestrus (during lactation or after weaning) was 89% (CW), 92% (IS19-7D), 80% (IS19-14D) and 77% (IS26-7D) (P>0.05) and subsequent litter size was 14.5 ± 0.5, 14.5 ± 0.6, 15.3 ± 0.5 and 15.2 ± 0.8, respectively (P>0.05). Sows mated during lactation had similar pregnancy rate and litter size to those mated after weaning. Hence, ongoing lactation for the first 2-9 d of pregnancy did not negatively affect fertility. A total of 50-64% of IS sows showed lactational oestrus, regardless of the stage of lactation. Pregnancy rates and litter size were similar to control sows, and were not affected by stage of lactation at mating.

Direct ovarian-uterine transfer of progesterone increases embryo survival in gilts.

This study employed a unilateral ovariectomy model to investigate the relevance of the local supply of progesterone (ovary) compared with the systemic supply of progesterone, in terms of embryo survival in the ipsilateral uterine horn as opposed to the contralateral uterine horn. Thirty gilts were unilaterally ovariectomised (ULO) during the luteal stage of their first oestrous cycle. Half of the ULO gilts were fed at 1.2 maintenance requirement (M), while the other half were fed at 2.4M. Across ULO gilts 0.8 more embryos survived in the ipsilateral horn compared with the contralateral horn at Day 35 of gestation (P<0.05). In ULO gilts on the 2.4M feed level the difference (+1.3; P<0.05) between the ipsi- and contralateral horn was more pronounced than on the 1.2M feed level (+0.4; NS). The higher feed level reduced circulating levels of systemic progesterone on Day 5 of pregnancy but not embryo survival at Day 35. However, post-implantation embryo survival was lower on the low feed level. In conclusion, these data indicate that local progesterone supply from the ovaries to the uterus contributes to the probability of embryo survival.

Reproductive cycles in pigs.

The oestrous cycle in pigs spans a period of 18-24 days. It consists of a follicular phase of 5-7 days and a luteal phase of 13-15 days. During the follicular phase, small antral follicles develop into large, pre-ovulatory follicles. Being a polytocous species, the pig may ovulate from 15 to 30 follicles, depending on age, nutritional status and other factors. During the luteal phase, follicle development is less pronounced, although there is probably a considerable turnover of primordial to early antral follicles that fail to further develop due to progesterone inhibition of gonadotrophic hormones. Nevertheless, formation of the early antral follicle pool during this stage probably has a major impact on follicle dynamics in the follicular phase in terms of number and quality of follicles. Generally, gilts are mated at their second or third estrous cycle after puberty. After farrowing, pigs experience a lactational anoestrus period, until they are weaned and the follicular phase is initiated, resulting in oestrus and ovulation 4-7 days after weaning. This paper describes the major endocrine processes during the follicular and luteal phases that precede and follow ovulation. The role of nutrition and metabolic status on these processes are briefly discussed.