Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Progesterone and Luteinizing hormone secretion patterns in early pregnant gilts
    Haen, Silke M. ; Heinonen, Mari ; Bjorkman, Stefan ; Soede, Nicoline M. ; Peltoniemi, Olli A.T. - \ 2020
    Reproduction in Domestic Animals 55 (2020)7. - ISSN 0936-6768 - p. 795 - 804.
    Corpus luteum - early pregnancy - gilt - luteinizing hormone - progesterone

    We studied luteinizing hormone (LH) pulsatility and episodic progesterone release of the corpus luteum (CL) on Day 11 and Day 21 in inseminated gilts and aimed to establish a relationship between these two hormones. Blood was collected at 15-min intervals for 12 hr on Days 11, 16 and 21 from a vena cava caudalis catheter. At euthanasia, eight gilts were pregnant and six gilts were not pregnant. Progesterone parameters (basal, mean, pulse frequency and pulse amplitude) did not differ between pregnant and non-pregnant gilts on Day 11, LH pulse frequency and amplitude tended to differ (p =.07 and p =.079). In pregnant gilts, basal and mean progesterone, progesterone pulse amplitude and frequency declined significantly from Day 11 to Day 21 (p <.05). A significant decline was also seen in the LH pulse amplitude from Day 11 to Day 21 (p <.05). None of the LH pulses was followed by a progesterone pulse within 1 hr on Day 21. On Day 11 and Day 21 appeared a synchronicity in the LH pulse pattern, as there were two or three LH pulses in 12 hr and these LH pulses appeared in the same time window. We conclude that on Day 11 and Day 21 of pregnancy in gilts, progesterone pulses do not follow an LH pulse within one hour. Further we demonstrated that the successful or not successful formation of a CL of pregnancy is independent of progesterone release on Day 11 after insemination. We confirmed the decline of progesterone from Day 11 to Day 21 in the vena cava caudalis and could demonstrate that this decline is partly due to lower progesterone pulse amplitude and frequency and that the decline occurs simultaneously with a decline in LH pulse amplitude.

    Follicular fluid steroid profile in sows: Relationship to follicle size and oocyte quality
    Costermans, N.G.J. ; Soede, N.M. ; Tricht, F. Van; Blokland, M. ; Kemp, B. ; Keijer, J. ; Teerds, K.J. - \ 2020
    Biology of Reproduction 102 (2020)3. - ISSN 0006-3363 - p. 740 - 749.
    follicle - granulosa cells - insulin-like growth factor - metabolism - porcine - steroid hormones

    Identification of reliable characteristics of follicle quality and developmental competence has been pursued in numerous studies, but with inconsistent outcomes. Here, we aimed to identify these characteristics by analysis of the follicular fluid (FF) steroid profile in relation to cumulus-oocyte complex (COC) morphology and follicle size, followed by molecular substantiation. Multiparous sows at weaning were used to facilitate analysis at the start of the follicular phase of the oestrus cycle. Sows with a higher average follicle size (≥5 mm vs. < 5 mm) had a higher follicular fluid β-estradiol concentration, but did not differ in other measured steroids. Sows with high compared to low percentage high-quality COCs (<70% vs. ≥70% high-quality) had follicular fluid with a higher concentration of β-estradiol, 19-norandrostenedione, progesterone, and α-testosterone, while the concentration of cortisol was lower. Transcriptome analysis of granulosa cells of healthy follicles of sows with a high percentage high-quality COCs showed higher abundance of transcripts involved in ovarian steroidogenesis (e.g., CYP19A2 and 3, POR, VEGFA) and growth (IGF1) and differential abundance of transcripts involved in granulosa cell apoptosis (e.g., GADD45A, INHBB). Differences in aromatase transcript abundance (CYP19A1, 2 and 3) were confirmed at the protein level. In addition, sows with a high percentage high-quality COCs lost less weight during lactation and had higher plasma IGF1 concentration at weaning, which may have affected COC quality. To the best of our knowledge, this study is also the first to report the relation between FF steroid profile and COC quality.

    Ovulatory response of weaned sows to an altered ratio of exogenous gonadotrophins
    Manjarín, Rodrigo ; García, Jose Carlos ; Hoving, Lia ; Soede, Nicoline M. ; Maj, Magdalena ; Tejerina, Juan Carlos Dominguez de; Kirkwood, Roy N. - \ 2020
    Animals 10 (2020)3. - ISSN 2076-2615
    Follicle - Gonadotrophins - Ovulation - Sows

    At weaning, 33 mixed parity Hypor sows received either an injection of 400 IU equine chorionic gonadotrophin and 200 IU human chorionic gonadotrophin (hCG) (PG600; n = 13), PG600 with an additional 200 IU hCG 24 h later (Gn800; n = 11), or served as non‐injected controls (n = 9). All gonadotrophin treated sows received an injection of 750 IU hCG at 80 h after weaning to induce ovulation (designated as time 0 h). At 0, 24, 36, 40, 44, 48, and 60 h, all sows were subject to transrectal ultrasonography to determine numbers and sizes of large (>6 mm) follicles and time of ovulation. The interval from injection of 750 IU hCG to ovulation was shorter in Gn800 compared to PG600 sows (p = 0.02), and more Gn800 sows had ≥9 preovulatory follicles compared to PG600 and controls (p = 0.02 and 0.003, respectively). Follicular cysts were evident in both PG600 and Gn800 sows.

    Physiological and molecular aspects of ovarian follicular developmental competence in sows
    Costermans, Natasja G.J. - \ 2020
    Wageningen University. Promotor(en): J. Keijer; B. Kemp, co-promotor(en): N.M. Soede; K.J. Teerds. - Wageningen : Wageningen University - ISBN 9789463951616 - 209

    Modern sow lines have been genetically selected for increased litter size. This increase in litter size, however, is also associated with higher piglet mortality. This piglet mortality can be partly explained by lower piglet birth weights and higher within-litter variation in birth weight. The main hypothesis of this thesis is that these factors, the lower piglet birth weights and the higher within-litter variation, are (at least partly) explained by impaired follicular development of sows during and after lactation, as this is the period in which antral follicles develop that contain the oocytes that will give rise to the next litter. Increased litter size also results in increased metabolic demands of modern sows during lactation, due to the necessary higher milk production. As the metabolic state highly influences follicular development, the increased metabolic demands may therefore impair follicular development and contribute to lower piglet birth weights and higher within-litter variation in piglet birth weight. It is not clear, however, which metabolic processes play the most significant roles in influencing follicular developmental competence in modern sows.

    Increased understanding of the origin of lower piglet birth weights in modern sows may be achieved by identification of molecular physiological characteristics which determine follicular developmental competence and how these are influenced by metabolism. Therefore, the aims of this thesis were: 1) To establish physiological and molecular characteristics of follicular developmental competence in sows and 2) To better understand physiological relations between the metabolic state of sows and follicular developmental competence.

    This thesis describes results from two pig studies. In the first study, follicular development and oocyte quality were assessed in multiparous sows at the onset of the follicular phase (at weaning), while in the second study, follicular development and oocyte quality were assessed in primiparous sows at the mid-follicular phase (48 after weaning). In both studies, the metabolic state of the sows was assessed to investigate physiological relations between metabolism during lactation and follicular developmental competence. In the first study, multiparous sows were all full-fed during lactation, while in the second study, half of the primiparous sows were restricted-fed during the last two weeks of lactation.

    In Chapter 2 of this thesis, I aimed to identify possible follicular causes of piglet birth weight variation by studying follicular development of multiparous sows at weaning in sows that differ in their estimated breeding value (EBV) for piglet birth weight variation (Study 1). In addition, relations between the metabolic state of these sows during lactation and follicular development were assessed. No significant relations between EBV for birth weight variation and any of the measured follicular or metabolic parameters were found. We did, however, find relations between metabolic losses and subsequent follicle development and –quality.  For example, average follicle size of the 15 largest follicles (the presumptive ovulatory follicle pool) was negatively related to serum creatinine levels, a marker for protein breakdown, and this follicle size was surprisingly, positively related to a higher backfat depth loss during lactation. As sows with a high backfat loss also had higher backfat levels at the start of lactation, it was hypothesised that modern sows with more backfat at the start of lactation are able to mobilise more energy from backfat during lactation to support follicular development thereby sparing protein reserves. To conclude, although unfortunately no relations between EBV and follicular development have been found, our study does show that energy mobilization from different sources during lactation, adipose tissues or muscle reflecting fat or lean mass, respectively, could have divergent effects on follicular development at weaning.

    Identification of molecular physiological characteristics which determine follicular developmental competence, may provide new insights in the origin of lower piglet birth weights in sows. Therefore, follicular granulosa cell gene and protein expression and follicular fluid composition were assessed in relation to two follicular competence markers, average follicle size (Chapter 3) and cumulus-oocyte complex (COC) morphology (Chapter 4) in the sows of Study 1. 

    In Chapter 3, I investigated granulosa cell processes in large and small follicles of the pool of 15 largest follicles (the presumptive ovulatory follicle pool). Granulosa cells of smaller antral follicles showed increased cell proliferation, which was accompanied by a metabolic shift towards aerobic glycolysis, similar to other highly proliferating cells. High granulosa cell proliferation rates in smaller follicles may be regulated via increased expression of receptors for locally produced mitogens, such as androgen receptor (AR) and epidermal growth factor receptor (EGFR). While granulosa cells of smaller follicles in the pool were more proliferative, granulosa cells of larger follicles expressed more maturation markers, such as insulin-like growth factor 1 (IGF1) and angiopoietin 1. Thus, in this chapter, granulosa cell processes and key genes were identified which may determine antral follicular developmental competence at the onset of the follicular phase.

    In Chapter 4, I studied follicular developmental competence, by studying relations between follicular fluid steroid profiles and oocyte health of the presumptive ovulatory follicle pool. Sows with a high compared to a low percentage healthy COCs (<70% vs. ≥70% healthy), had higher 17β-estradiol, 19-norandrostenedione, progesterone and α-testosterone levels, while cortisol levels were lower. In addition, a larger average follicle size of the 15 largest follicles was related to higher 17β-estradiol levels. Transcriptome and selective protein analysis of granulosa cells of healthy follicles of sows with a high percentage healthy COCs showed increased expression of genes involved in steroidogenesis and follicular maturation, and a differential expression of genes regulating granulosa cell apoptosis. Also the metabolic state of the sows affected the level of COC health, as sows with a high percentage healthy COCs lost less weight during lactation and had higher serum IGF1 levels at weaning. The level of COC health at the onset of the follicular phase was thus highly related to follicular steroidogenesis.

    Both follicle size and percentage healthy COCs, two follicular competence markers, were found to be related to follicular fluid steroid levels. If relations between follicular and serum steroid levels could be established, serum steroid profiles may be used to monitor follicular development. This was investigated in Chapter 5, using samples of Study 1 and 2. I identified serum steroids that reflect follicular development in the early stages of the follicular phase and established whether follicular fluid steroid levels correspond to those in serum. Serum steroid levels were never related to average follicle size of the pool. Moreover, no difference in serum steroid levels was observed when levels at the onset of the follicular phase were compared to levels in the mid-follicular phase. Serum steroid levels therefore poorly reflect the developmental stage of the follicle pool in the first half of the follicular phase of the estrous cycle and can therefore unfortunately not be used to monitor follicular development.

    Another way to identify possible follicular causes of piglet birth weight and within-litter variation in birth weight, is by reducing lactational feed intake in sows. A low lactational feed intake increases mobilization of energy from body tissues which has been found to negatively influence piglet birth weight and variation in piglet birth weight of the next litter. Studying effects of lactational feed restriction on follicular and oocyte developmental competence, may therefore elucidate follicular characteristics that finally influence piglet birth weight and variation in piglet birth weight. Chapter 6 describes effects of feed restriction during the last two weeks of a 24-day lactation on follicular developmental competence at the mid-follicular phase, in primiparous sows (Study 2). Feed restriction impaired follicular developmental competence, as shown by a smaller average size of the 15 largest follicles and reduced cumulus-oocyte complex expansion after 22h in vitro maturation. Feed restriction also impaired oocyte quality, which was shown by a delayed zygote development 24h after in vitro fertilization and a higher incidence of polyspermy. This reduced follicular and oocyte developmental competence may be influenced by the lower IGF1 and steroid levels detected in the follicular fluid of restricted-fed sows. Together, these results implicate that lactational feed restriction impairs follicular steroid and growth factor production which reduces oocyte developmental competence. These impairments may at least partly explain lower piglet birth weights.

    Lactational feed intake does not only affect sow performance, but also affects piglet performance by changing sow milk production, as described in Chapter 7 (Study 2). A higher feed intake during lactation resulted in a higher milk fat percentage at weaning and a higher total milk fat and protein production in the last week of lactation. Both a better body condition (higher body weight, loin muscle depth and backfat depth) at parturition and more body tissue mobilization (backfat depth loss and loin muscle depth loss) were related to a higher milk fat and/or protein production in the last week of lactation. Together, findings from Chapter 6 and 7 suggest that a higher lactational feed intake benefits both sow performance, by supporting follicular development during lactation, as well as piglet performance, by increasing sow milk production. However, more tissue mobilization during lactation impairs follicular developmental competence while it may be beneficial for milk production which supports litter weight gain. It therefore remains a challenge to design optimal feeding strategies that benefit both the current litter (sustained milk production) as well as the next litter (supporting follicular development).

    In conclusion, this thesis shows that follicular developmental competence of the presumptive ovulatory follicle pool is associated with more granulosa cell differentiation and less proliferation, more steroidogenesis and a higher IGF1 production. In Chapter 8, it is argued that these identified processes may also be important for subsequent embryo and foetal survival and development, and finally, piglet birth weight and survival. The metabolic state of modern sows during lactation highly influences follicular developmental competence, already from the first half of the follicular phase onward. In addition, in primiparous modern sows, lactational weight loss influenced litter characteristics of the next litter. This provides further evidence for the hypothesis of this thesis that impairments in follicular developmental competence as established during lactation may at least partially explain the reduced reproductive performance in the next cycle and lower piglet birth weights. The degree and type of body tissue mobilization i.e. adipose tissue or lean mass, highly influences follicular development during lactation as well as milk production and composition, which are both important factors for sow performance. It seems that especially mobilization of energy from lean mass in sows with low adipose tissue reserves, negatively impacts follicular developmental competence, while mobilization of protein from lean mass may be beneficial for milk protein production to support piglet growth. It therefore remains a challenge to optimize current sow management strategies benefit sow- and piglet performance.

    IGF-1 concentration patterns and their relationship with follicle development after weaning in young sows fed different pre-mating diets
    Han, T. ; Björkman, S. ; Soede, N.M. ; Oliviero, C. ; Peltoniemi, O.A.T. - \ 2020
    Animal 14 (2020)7. - ISSN 1751-7311 - p. 1493 - 1501.
    follicular development - IGF - metabolic state - sow body condition - Sow reproduction

    Piglet birth weight and within-litter birth weight variation are important for piglet survival and growth. Pre-mating diets may improve IGF-1 and follicle development during the weaning-to-oestrus interval (WEI) and subsequent piglet birth weight. The objective of this study was to modulate IGF-1 concentration during late lactation and the WEI of young sows by using specific pre-mating diets supplemented with microfibrillated cellulose (MF), l-carnitine (LC) or l-arginine (AR). A further objective was to investigate the relationship between IGF-1 and subsequent follicle development and oestrus and ovulation characteristics. In total, 56 first-parity and 20 second-parity sows in three consecutive batches were used for this experiment. Sows received daily either wheat (CON) or wheat plus MF, LC or AR at one of two supplementation levels (low and high) during last week of lactation and WEI. From weaning onwards, follicle and corpus luteum (CL) diameters were repeatedly measured with ultrasound. Blood samples were collected during the WEI for IGF-1 and on day 21 of pregnancy for progesterone analyses, respectively. Insulin-like growth factor-1 concentration, follicle diameter, oestrus and ovulation characteristics and CL diameter were not affected by pre-mating diets. Low IGF-1 class (≤156 ng/ml, N = 22) sows had smaller follicles at weaning (3.5 v. 3.8 mm, P < 0.05) and a longer weaning-to-ovulation interval (147.2 v. 129.8 h, P < 0.05) than high IGF-1 class sows. In first-parity sows, high loin muscle depth (LM) loss sows (≥8%, N = 28) had lower IGF-1 concentrations at weaning (167 v. 214 ng/ml, P < 0.05) compared to low LM loss sows (<8%, N = 28). However, after weaning, IGF-1 concentrations increased and did not differ between high LM loss and low LM loss sows. In conclusion, the different supplemented compounds in pre-mating diets did not improve IGF-1 concentrations around weaning in young sows. Furthermore, high body condition loss caused lower IGF-1 concentrations at weaning, but these levels rapidly recovered after weaning and were related to follicle development and the interval from weaning to ovulation.

    Consequences of negative energy balance on follicular development and oocyte quality in primiparous sows
    Costermans, N.G.J. ; Teerds, K.J. ; Middelkoop, Anouschka ; Roelen, B.A.J. ; Schoevers, E.J. ; Tol, H.T.A. van; Laurenssen, B.F.A. ; Koopmanschap, R.E. ; Zhao, Yu ; Blokland, Marco ; Tricht, E.F. van; Zak, L.J. ; Keijer, J. ; Kemp, B. ; Soede, N.M. - \ 2020
    Biology of Reproduction 102 (2020)2. - ISSN 0006-3363 - p. 388 - 398.
    Metabolic demands of modern hybrid sows have increased over the years, which increases the chance that sows enter a substantial negative energy balance (NEB) during lactation. This NEB can influence the development of follicles and oocytes that will give rise to the next litter. To study effects of a lactational NEB on follicular development, we used 36 primiparous sows of which 18 were subjected to feed restriction (3.25 kg/day) and 18 were full-fed (6.5 kg/day) during the last 2 weeks of a 24.1 ± 0.3 day lactation. Feed restriction resulted in a 70% larger lactational body weight loss and 76% higher longissimus dorsi depth loss, but similar amounts of backfat loss compared to the full fed sows. These changes were accompanied by lower plasma insulin-like growth factor 1 (IGF1) and higher plasma creatinine levels in the restricted sows from the last week of lactation onward. Ovaries were collected 48 h after weaning. Restricted sows had a lower average size of the 15 largest follicles (−26%) and cumulus–oocyte complexes showed less expansion after 22 h in vitro maturation (−26%). Less zygotes of restricted sows reached the metaphase stage 24 h after in vitro fertilization and showed a higher incidence of polyspermy (+89%). This shows that feed restriction had severe consequences on oocyte developmental competence. Follicular fluid of restricted sows had lower IGF1 (−56%) and steroid levels (e.g., β-estradiol, progestins, and androgens), which indicated that follicles of restricted sows were less competent to produce steroids and growth factors needed for oocytes to obtain full developmental competence.
    Genetic selection for better mothers improves piglet survival in both conventional and group-farrowing systems
    Dunkelberger, Jenelle R. ; Vogelzang, Roos ; Peet-Schwering, C.M.C. van der; Soede, N.M. ; Knol, Egbert F. - \ 2019
    Genetic selection for better mothers improves piglet survival in both conventional and group-farrowing systems
    Dunkelberger, Jenelle R. ; Vogelzang, Roos ; Peet-Schwering, C.M.C. van der; Soede, N.M. ; Knol, Egbert F. - \ 2019
    Steroid profile of porcine follicular fluid and blood serum: Relation with follicular development
    Costermans, N.G.J. ; Soede, N.M. ; Blokland, M.H. ; Tricht, E.F. van; Keijer, J. ; Kemp, B. ; Teerds, K.J. - \ 2019
    Physiological Reports 7 (2019)24. - ISSN 2051-817X
    The aim of this study was to identify follicular fluid (FF) steroids which reflect follicular development in the early stages of the follicular phase and to establish whether the levels of these FF steroids correspond to their levels in serum. If these relations are established, serum steroid profiles may be used to monitor follicular development already in this early stage of the follicular phase. We used samples of two experiments, one with multiparous sows at the onset of the follicular phase (weaning) and one with primiparous sows at the midfollicular phase (48 hr after weaning). Complete steroid profiles were measured in pooled FF of the 15 largest follicles and serum using high‐performance liquid chromatography‐tandem mass spectrometry. In experiment 1, pooled FF volume, as a measure for average follicle size, tended to be positively related to higher FF 17β‐estradiol levels (β = 0.56, p = .08). In experiment 2, a larger FF volume was related not only to FF higher 17β‐estradiol levels (β = 2.11, p < .001) but also to higher levels of β‐nortestosterone (β = 1.15, p < .0001) and its metabolite 19‐norandrostenedione (β = 1.27, p < .01). In addition, FF volume was related to higher FF 17α‐OH‐pregnenolone (β = 1.63, p = .03) and 17α‐OH‐progesterone (β = 1.83, p < .001), which could indicate that CYP17,20‐lyase activity is limiting for 17β‐estradiol production in larger follicles at the beginning of the follicular phase. In serum, most of the steroids were present at lower levels compared to FF, except for the corticosteroids. Serum progestins and androgens were never related to follicle pool volume and steroid levels did not differ in the midfollicular phase compared to the onset of the follicular phase in the second experiment. Serum steroid levels therefore poorly reflect the developmental stage of the follicle pool in the first half of the follicular phase of the estrous cycle in sows.
    Factors affecting estrus and ovulation time in weaned sows with induced ovulation by GnRH administration in different seasons
    Pearodwong, Pachara ; Tretipskul, Chanyuth ; Soede, Nicoline M. ; Tummaruk, Padet - \ 2019
    Journal of Veterinary Medical Science 81 (2019)11. - ISSN 0916-7250 - p. 1567 - 1574.
    Buserelin - Ovulation induction - Season - Sow

    Follicle development in post-weaning sows is influenced by various factors. To control ovulation time using hormone, factors that influence ovulation should be investigated. The present study was performed to evaluate the effect of GnRH (buserelin) administration in relation to season and sow parameters on ovulation time in weaned sows. Seventy-seven weaned sows were divided into the following groups: control (hot season, n=21; cool season, n=16) and treatment (hot season, n=22; cool season, n=18). Sows were kept in a close house equipped with an evaporative cooling system. Ovulation time was determined every 6 hr using transrectal ultrasonography. Administration of 10 µg buserelin at 72 hr after weaning affected estrus-to-ovulation interval (EOI) and weaning-to-ovulation interval (WOI) in sows (P<0.05). The percentage of sows that ovulated between 44–56 hr after injection was higher in the cool season than in hot season (P<0.05). Weaning-to-estrus interval (WEI) and injection-to-estrus interval (IEI) were affected by season (P<0.05). Body condition score (BCS) of sows influenced EOI (P<0.01). Sows with low backfat thickness, lactation length <20 days, or litter weight ≥67 kg, had delayed injection-to-ovulation interval (P<0.05). In conclusions, buserelin administration (10 µg, at 72 hr after weaning) advanced ovulation. Hot season prolonged ovulation time. Sows that were weaned with lactation length of at least 20 days, litter weight less than 67 kg, or BCS of at least 3, had better responses to buserelin injection. High backfat reserve after weaning is important for ovulation induction response by buserelin injection.

    In ovaries with high or low variation in follicle size, granulosa cells of antral follicles exhibit distinct size-related processes
    Costermans, N.G.J. ; Keijer, J. ; Schothorst, E.M. van; Kemp, B. ; Keshtkar, S. ; Bunschoten, J.E. ; Soede, N.M. ; Teerds, K.J. - \ 2019
    Molecular Human Reproduction 25 (2019)10. - ISSN 1360-9947 - p. 614 - 624.
    Antral follicle size might be a valuable additive predictive marker for IVF outcome. To better understand consequences of antral follicle size as a marker for reproductive outcome, we aimed to obtain insight in follicle size-related granulosa cell processes, as granulosa cells play an essential role in follicular development via the production of growth factors, steroids and metabolic intermediates. Using the pig as a model, we compared gene expression in granulosa cells of smaller and larger follicles in the healthy antral follicle pool of sows which had a high variation versus low variation in follicle size. Selected gene expression was confirmed at the protein level. Granulosa cells of smaller antral follicles showed increased cell proliferation, which was accompanied by a metabolic shift towards aerobic glycolysis (i.e. the Warburg effect), similar to other highly proliferating cells. High granulosa cell proliferation rates in smaller follicles might be regulated via increased granulosa cell expression of the androgen receptor and the epidermal growth factor receptor, which are activated in response to locally produced mitogens. While granulosa cells of smaller follicles in the pool are more proliferative, granulosa cells of larger follicles express more maturation markers such as insulin-like growth factor 1 (IGF1) and angiopoietin 1 (ANGPT1) and are therefore more differentiated. As both higher IGF1 and ANGPT1 have been associated with better IVF outcomes, the results of our study imply that including smaller follicles for oocyte aspiration might have negative consequences for IVF outcome.
    Granulosa cells of ovarian antral follicles exhibit distinct follicle size-related processes
    Costermans, N.G.J. ; Teerds, K.J. ; Schothorst, E.M. van; Bunschoten, J.E. ; Keijer, J. ; Soede, N.M. - \ 2019
    GSE125189 - PRJNA515499 - Sus scrofa
    Antral follicle size might be a valuable additive predictive marker for IVF outcome. However, while some studies show positive relations between follicle size and reproductive outcome, others have not been successful in establishing this relation. To better understand consequences of antral follicle size for reproductive outcome, we aimed to obtain insight in follicle size-related granulosa cell processes, as granulosa cells play an essential role in follicular development via the production of growth factors, steroids and metabolic intermediates, needed for follicular growth and oocyte development. Using pigs as a model, we compared gene and protein expression in granulosa cells of smaller and larger follicles in the healthy antral follicle pool at the start of the follicular phase of the estrous cycle. In sows, the early antral follicle pool is very heterogeneous when e.g. size and steroid content of the follicular fluid are considered. To which extent this variety contributes to the developmental competence of the follicles is not clear. Therefore, sows with high variation in antral follicle size (HighVAR) as well as sows with low variation in antral follicle size (LowVAR) were used. Granulosa cells of smaller antral follicles in the healthy antral follicle pool show increased cell proliferation, which was accompanied by a metabolic shift towards aerobic glycolysis (i.e. the Warburg effect), similar to other highly proliferating cells. High granulosa cell proliferation rates in smaller follicles might be regulated via increased granulosa cell expression of AR and EGFR which are activated in response to locally produced mitogens. While granulosa cells of smaller follicles in the pool were more proliferative, indicative of higher follicular growth, granulosa cells of larger follicles in the pool showed less proliferation and were more differentiated, as they showed a higher expression of follicular maturation marker IGF1 and ANGPT1. Our results imply that the inclusion of strict criteria of antral follicle size in IVF protocols might improve reproductive outcome. In addition, we have granulosa cell gene expression of healthy follicles to unravel underlying mechanisms of differences in COC morphology. We compared gene expression in sows with low vs. high-COC-health and found a decreased expression of genes involved in ovarian steroidogenesis (e.g. CYP19A1, ADM, SPP1) and higher expression of genes involved in follicular atresia (e.g. GADD45A, INHBB) in sows with low-COC-health. Thereby we have identified several genes which may serve as markers for follicle developmental competence.
    Effect of IGF-1 level at weaning on subsequent luteal developement and progesterone production in primiparous sows
    Han, Taehee ; Björkman, S. ; Soede, N.M. ; Oliviero, C. ; Peltoniemi, O. - \ 2019
    In: Abstract book 11th European Symposium of Porcine Health Management (ESPHM). - - p. 82 - 82.
    Insulin-like growth factor-1 (IGF-1) is known to be related to follicle and oocyte development in sows. Wehypothesized that a higher IGF-1 level at weaning may derive better luteal development during early pregnancyin primiparous sows. We retrospectively assigned 56 primiparous sows into high- (HI, ? 255 ng/ml, n = 14),medium- (MI, 150 – 255 ng/ml, n = 28) or low- (LI, ? 150 ng/ml, n =14) group based on their plasma IGF-1level at weaning. Follicle diameter was measured at weaning, three days after and one day after estrus withtransrectal ultrasonography. Blood sampling was performed on the same day as ultrasonography. At 21 day afterinsemination, corpus luteum (CL) size and plasma progesterone level were measured. MIXED and GLIMMIXmodels (SAS 9.4) were used for analyses. The IGF-1 level at three days after weaning and one day after estrusremained significantly different between the three groups. Follicle diameter at weaning of HI sows was largerthan that of LI sows (p = 0.02) but similar with that MI sows (3.5 ± 0.1 vs. 3.6 ± 0.1 vs. 3.8 ± 0.1 mm, for LI,MI and HI, respectively). However, further follicle development and pregnancy rate (93.3 %) were not differentbetween the groups. In pregnant sows, LI sows tended to have larger CL at day 21 (p = 0.08) compared to MIand HI sows (10.1 ± 0.2 vs. 9.9 ± 0.1 vs. 9.4 ± 0.2 mm, for LI, MI and HI, respectively). In addition,progesterone level tended to be positively correlated with CL diameter (? = 3.0 (ng/ml)/mm, p = 0.09). Thus,although post-weaning IGF-1 was not related with follicle development at ovulation, it was negatively relatedwith subsequent CL development. Subsequent studies focusing on the relationship between post-weaning IGF-1level and luteinizing hormone will be needed.
    Granulosa cells of ovarian antral follicles exhibit distinct follicle size-related processes
    Costermans, N.G.J. ; Keijer, J. ; Kemp, B. ; Schothorst, E.M. van; Kersthkar, Shohreh ; Bunschoten, J.E. ; Soede, N.M. ; Teerds, K.J. - \ 2019
    In: Trade-offs in science – Keeping the Balance. - Wageningen University & Research - p. 15 - 15.
    Recent advances in pig reproduction: focus on impact of genetic selection for female fertility
    Nieuwenhuizen-Soede, Nicoline - \ 2019
    GnRH‐agonist deslorelin implant alters the progesterone release pattern during early pregnancy in gilts
    Haen, S.M. ; Heinonen, M. ; Kauffold, J. ; Heikinheimo, M. ; Hoving, Lia ; Soede, N.M. ; Peltoniemi, O.A.T. - \ 2019
    Reproduction in Domestic Animals 54 (2019)3. - ISSN 0936-6768 - p. 464 - 472.
    The aim of this study was to investigate the relationship of progesterone (P) and luteinizing hormone (LH) during recognition and establishment of pregnancy in the gilt. Therefore, the effects of eliminating episodic LH pulses on P patterns were determined during early pregnancy. To this end, a slow‐release GnRH implant deslorelin was used for GnRH down‐regulation. A group of gilts (GnRHa, n = 8) was implanted with the GnRH‐agonist on Day 11 of pregnancy, while a control group (C, n = 5) was treated with a non‐impregnated placebo implant. Blood was collected via a vena cava caudalis catheter at 10‐min intervals for 8 hr on Day 16 and 21 of pregnancy. As expected, the GnRH implant reduced LH secretion (p < 0.01) and abolished LH pulses completely at Day 16 and Day 21 of pregnancy. On Day 16, there was no difference in P levels between the treatments. However, on Day 21, the GnRH‐agonist treatment led to significantly increased P concentrations (p < 0.01) compared with the control gilts. Progesterone was secreted in a pulsatile manner in both treatment groups and no relationship between LH pulsatility and P pulsatility was observed. In conclusion, abolishment of LH pulsatility did not affect the pulsatile pattern of P secretion but led to an unexpected overall increase in P on Day 21 of pregnancy; this effect was delayed and occurred 10 days after commencing treatment with the GnRH depot agonist. The elevation of P on Day 21 of pregnancy in the GnRHa group suggests either a reduced negative feedback effect or an increased autocrine response by the corpora lutea.
    Follicular development of sows at weaning in relation to estimated breeding value for within-litter variation in piglet birth weight
    Costermans, N.G.J. ; Teerds, K.J. ; Keijer, J. ; Knol, E.F. ; Koopmanschap, R.E. ; Kemp, B. ; Soede, N.M. - \ 2019
    Animal 13 (2019)3. - ISSN 1751-7311 - p. 554 - 563.
    lactation - litter uniformity - metabolism - reproduction - sows

    In this study we aimed to identify possible causes of within-litter variation in piglet birth weight (birth weight variation) by studying follicular development of sows at weaning in relation to their estimated breeding value (EBV) for birth weight variation. In total, 29 multiparous sows (parity 3 to 5) were selected on their EBV for birth weight variation (SD in grams; High-EBV: 15.8±1.6, N=14 and Low-EBV: −24.7±1.5, N=15). The two groups of sows had similar litter sizes (15.7 v. 16.9). Within 24 h after parturition, piglets were cross-fostered to ensure 13 suckling piglets per sow. Sows weaned 12.8±1.0 and 12.7±1.0 piglets, respectively, at days 26.1±0.2 of lactation. Blood and ovaries were collected within 2 h after weaning. The right ovary was immediately frozen to assess average follicle size and percentage healthy follicles of the 15 largest follicles. The left ovary was used to assess the percentage morphologically healthy cumulus-oocyte complexes (COCs) of the 15 largest follicles. To assess the metabolic state of the sows, body condition and the circulating metabolic markers insulin, IGF1, non-esterified fatty acid, creatinine, leptin, urea and fibroblast growth factor 21 were analysed at weaning. No significant differences were found in any of the measured follicular or metabolic parameters between High-EBV and Low-EBV. A higher weight loss during lactation was related to a lower percentage healthy COCs (β= −0.65, P=0.02). Serum creatinine, a marker for protein breakdown, was negatively related to average follicle size (β= −0.60, P=0.05). Backfat loss during lactation was related to a higher backfat thickness at parturition and to a higher average follicle size (β=0.36, P<0.001) at weaning. In conclusion, we hypothesise that modern hybrid sows with more backfat at the start of lactation are able to mobilise more energy from backfat during lactation and could thereby spare protein reserves to support follicular development.

    Lactation oestrus: prevention or opportunity
    Kemp, B. ; Soede, N.M. - \ 2018
    In: 9. Leipziger Tierärztekongress. LBH: Tagungsband 3. - Lehmanns Media GmbH - p. 32 - 36.
    Variation in the follicle pool of weaned sows: granulosa cell gene expression in healthy small antral follicles
    Costermans, N.G.J. ; Keijer, J. ; Kemp, B. ; Soede, N.M. ; Teerds, K.J. - \ 2018
    - 1 p.
    Over the last decades, pigs have been genetically selected to produce larger litters. This resulted in decreased piglet birth weights and increased within-litter variation in piglet birth weight which are both related to higher piglet mortality.
    The aim of this study was to identify the underlying mechanism of variation in the follicle pool by studying differential gene expression of granulosa cells of large and small follicles within the same antral follicle pool at the time of weaning (=onset of the follicular phase).
    The right ovary of 29 multiparous sows was collected within 2 hours after weaning and immediately snap-frozen. All visible antral follicles were measured and classified as either healthy or atretic by a cleaved caspase-3 immunostaining. The variation in follicle size of the 10 largest healthy follicles was used to select a total of eight sows for further analysis; four sows with the largest variation in follicle size of the 10 largest healthy follicles and four sows with the smallest variation in follicle size. Granulosa cells of the 3 largest and 3 smallest healthy follicles of each of the 8 animals were isolated using laser-capture microdissection and differential gene expression was analyzed by individual hybridization with porcine whole-genome microarrays.
    Average follicle size of the 3 largest and 3 smallest healthy follicles of the sows selected for large variation in follicle size was 7.1±0.8mm vs. 3.9±0.9mm and was 6.1±0.8 vs. 4.9±1.1mm for the sows selected for small variation in follicle size. A core set of 33 genes was differentially expressed in large vs. small follicles in both the large variation follicle pools as the small variation follicle pools. The role of these core set genes will be analyzed to investigate the underlying mechanism of variation in the healthy antral follicle pool.
    Surprisingly, genes involved in the final steps of the steroid synthesis pathway were already expressed in early antral follicles. Steroid profiles in serum and follicular fluid have been measured using LC-MS and data are currently analysed.


    Recent advances in pig reproduction : Focus on impact of genetic selection for female fertility
    Kemp, Bas ; Silva, Carolina L.A. Da; Soede, Nicoline M. - \ 2018
    Reproduction in Domestic Animals 53 (2018)S2. - ISSN 0936-6768 - p. 28 - 36.
    genetic selection - litter size - management - sow - weaning-to-oestrus interval

    In the past 30 years, sows have been successfully selected for a shorter weaning-to-oestrus interval and increased litter size. This review discusses the consequences of this selection for the reproductive physiology of sows, including the consequences for litter characteristics at birth. It also discusses breeding and management opportunities to deal with this changed genetics.

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