Placental Traits Research Articles

Association analysis of polymorphisms at GLRB, GRIA2, and GASK1B genes with reproductive traits in Dazu Black Goats

Reproductive traits are essential economic traits in goats. This study aimed to analyze the relationship between single nucleotide polymorphisms (SNPs) within the genes of GLRB, GRIA2, and GASK1B, and reproductive traits (kidding traits and placental traits) in goats. We used the resequencing data of 150 Dazu Black Goats to perform correlation analysis with the average litter size. We screened thirteen SNPs loci in introns and then used the Sanger method to genotype the remaining 150 Dazu Black Goats. The results showed that a total of six SNPs were screened. Three SNPs related to litter size and live litter size (g.28985790T > G, g.28986352A > G, and g.28987976A > G); one SNP related to total cotyledon area (g.29203243G > A); two SNPs related to placental efficiency (g.30189055G > A and g.30193974C > T); one SNP associated with cotyledon support efficiency (g.30193974C > T). The qPCR results showed that GLRB, GRIA2, and GASK1B were all highly expressed in the udder, kidney, uterus, and ovary. It indicated that these three candidate genes might affect the reproductive traits, which could be used as candidate markers for reproductive traits in Dazu Black Goats. Moreover, association studies on a large scale are still needed to figure out what effect these SNPs have on reproductive traits.

Impact of high-fat diet consumption during prolonged period of pregnancy on placenta structures and umbilical vascular growth in goats

This study aimed to verify the impact of high-fat diet consumption for a prolonged period on oxidative stress, fetal growth, umbilical vascular system, and placental structures in pregnant goats. Twenty-two pregnant goats were grouped into the control diet (n= 11) and fat diet (n = 11). Flaxseed meal was added to the fat diet, replacing the corn grain of concentrate, from gestational day 100 to delivery date. Diets were isonitrogenous and isoenergetic, differing in fat content (2.8% vs. 6.3% dry matter). The fat group showed higher feed intake and total plasma lipid levels than the control group (P < 0.001). No difference was found in placentome, and umbilical vascular development. Fat diet-fed goats exhibited a lower systolic peak in the umbilical artery. At delivery, placental traits were similar with the exception of the cotyledon width (P = 0.0075), which was smaller in the fat group and cotyledon surface (P = 0.0047) for multiple pregnancy of fat diet. Cotyledonary epithelium showed more intense staining of lipid droplets and a greater area for lipofuscin staining in the fat group compared to control group (P < 0.001). The mean live weight of the kids was lower in the fat group in the first week after delivery than in control group. Thus, in goats, the continuous administration of a high-fat diet during pregnancy does not appear to modify the fetal-maternal vascular structures but has an impact on a part of the placental structure; therefore, its use must be carefully evaluated.

Determination of Effect of Placental Characteristics on Lamb Birth Weight in Bafra Sheep by Path Analysis

Path analysis is used to describe the directed dependencies among a set of variables and applied in animal breeding to improve breeding practices. Therefore, the aim of this study was to examine the direct and indirect effect of some placental traits on lamb birth weight born to Bafra sheep breed using path analysis. For this aim, the relationship between lamb birth weight and seven placental traits (placental weight; PW, total cotyledon numbers; TCN, total cotyledon surface area; TCSA, cotyledon efficiency; CE, total cotyledon volume; TCV, volumetric cotyledon efficiency; VCE, placenta efficiency; PE) were studied in 40 singleton - bearing ewe. Birth weight (BW), lamb sex, and placental measurements were recorded within 12 h after parturition. The direct effects of PE on birth weight were found statistically significant (p

Placental traits, and plasma concentration and placental mRNA expression of IGF-I in Bafra sheep breed with different birth type

Insulin-like growth factors (IGF) promote follicle development, ovulation, and embryonic development and affect placental and fetal growth and development in many mammalian species. Therefore, this study aimed to determine the relationship between birth type, plasma concentration, and placental mRNA expression of IGF-I in Bafra ewes. A total of 30 ewes, which have single (n=15) or twin (n=15) gestation and at least gave birth to 2, have been used as experimental animals. Before mating, blood samples were collected from the jugular vena of all ewes. Following lambing, birth type, live weight, and sex of lambs and placental traits have been recorded. Plasma IGF-I concentration was determined using a commercial ELISA kit. IGF-I gene expression level has been determined by real-time quantitative polymerase chain reaction. No difference was found between single and twin-bearing sheep in terms of placental weight and various cotyledon characteristics in the study. In contrast, total cotyledon weights were lower in singleton gestation than those in twin (P<0.05). Similarly, the total and medium cotyledon number and cotyledon efficiency of Bafra ewes with single deliveries were lower than Bafra sheep with twin births (P<0.05). Although the birth type did not affect both placental gene expression level and plasma concentration of IGF-I, sheep that gave birth to twins exhibited 0.908 times more gene expression than that to single births. The study results showed that birth type did not affect plasma IGF-I concentration and placental IGF-I gene expression level in Bafra sheep breed but changed placental characteristics.

Effects of flush feeding strategy before breeding on reproductive performance of modern replacement gilts: impacts on ovulation rate and litter traits

AbstractThe effects of two feed levels offered during two estrous cycles before insemination were evaluated on the reproductive performance of gilts. A total of 93 gilts (PIC Hendersonville, TN) were individually housed and manually fed twice a day with 2.1 or 3.6 kg/d of a corn and soybean meal-based diet (3.15 Mcal ME/kg and 0.64% standardized ileal digestible lysine), during two estrous cycles before breeding (cycle 1, between first and second estrus; cycle 2, between second and third estrus). Gilts were weighed at the beginning of the experiment, at second and third estrus, and at slaughter (30.2 ± 1.2 d of gestation). Follicles were counted at second estrus, and the embryo-placental units and the corpora lutea were individually counted, measured, and weighed at slaughter. Gilts fed 3.6 kg/d had greater BW gain during cycle 1 and cycle 2 (P < 0.001; + 9.8 kg and + 10.0 kg, respectively) becoming heavier at second and third estrus (P < 0.001). At second estrus, gilts fed 3.6 kg/d had 1.6 more medium-large follicles (P = 0.074) but no difference in follicle size (P = 0.530) was observed. Gilts fed 3.6 kg/d in cycle 1 or cycle 2 had a greater ovulation rate at third estrus (P < 0.016) than those receiving 2.1 kg/d. Also, 3.6 kg/d in cycle 2 increased early embryo mortality (P = 0.006; 2.3 vs. 1.1 dead embryos) and consequently reduced total embryo survival (P = 0.002; 84.6 vs. 90.1%). Gilts fed 3.6 kg/d during cycle 1 had two more total embryos (P < 0.001; 17.2 vs. 15.1) and two more vital embryos on day 30 (P < 0.001; 16.7 vs. 14.5) in comparison with gilts fed 2.1 kg/d. The coefficient of variation for placental length was greater for gilts fed 3.6 kg/d during cycle 1 (P = 0.003). No further significant effects of feeding levels were observed on embryo and placental traits (P ≥ 0.063). These results suggest that the feeding level during the first cycle after pubertal estrus is crucial to set ovulation rate and potential litter size for breeding at next estrus. However, flush feeding gilts before insemination can negatively impact litter size by reducing embryo survival when breeding at third estrus.

Stage-specific feed intake restriction differentially regulates placental traits and proteome of goats

A total of twenty-four healthy twin-bearing Liuyang black goats were allocated to two trials. In Trial 1, twelve goats received either the control diet (CG, n 6, 100 % feed) or restricted diet (RG, n 6, 60 % feed of CG) from gestation days 26 to 65 after synchronisation. In Trial 2, the remaining goats were randomly and equally divided into two treatments: CG and RG from days 95 to 125 of gestation. Placental traits, fetal weight, serum parameters, nitric oxide (NO), angiogenesis gene expression and cotyledon proteome were measured at the end of each trial. In early pregnancy, the total and relative weights of placenta, uterine caruncle and cotyledon, as well as fetus, were increased (P<0·05) in RG. The NO content in maternal serum was also increased (P<0·05) in RG. In all, fifty differentially expressed proteins were identified in cotyledon. The up-regulated proteins are related to proliferation and fission of trophoblast cell and the placenta angiogenesis. During the late pregnancy trial, placental weight was increased (P<0·05) in RG, but weight of the fetus was decreased (P<0·05). The capillary density in the cotyledon was also decreased (P<0·01). A total of fifty-eight proteins were differentially expressed in cotyledon. The up-regulated proteins in RG are related to placenta formation, blood flow regulation and embryonic development. These results indicated that feed intake restriction during gestation influenced the placental and fetal development in a stage-dependent manner. These findings have important implications for developing novel nutrient management strategies in goat production.

Birth weight, umbilical and placental traits in relation to neonatal loss in cloned pigs

Cloned piglets generated through somatic cell nuclear transfer (SCNT) have a high rate of neonatal death. Postnatal loss is associated with low birth weight, umbilical status and placental parameters in fertilisation-derived piglets. To investigate whether or not this relationship also exists in cloned piglets, birth weight, umbilical status, placental parameters, placental morphology and gene expression pattern were compared among four piglet groups, namely, SCNT-derived male piglets that died within 4 days (SCNT-DW4), SCNT-derived male piglets that survived over 4 days (SCNT-SO4), artificial insemination (AI)-generated male piglets that died within 4 days (AI-DW4) and AI-generated male piglets that survived over 4 days (AI-SO4). Results showed that the occurring frequency of abnormal umbilical cord in SCNT-DW4 piglets was significantly higher than that in AI-SO4 piglets but was similar to that in SCNT-SO4 and AI-DW4 piglets. The birth weight, placental surface area and placental weight of AI-SO4, AI-DW4 and SCNT-SO4 groups were similar but were significantly higher than those in SCNT-DW4 group. SCNT-SO4 placentas exhibited mild but SCNT-DW4 placentas showed severe morphological abnormalities compared with AI-SO4 placentas. The expression profiles of imprinting, angiopoiesis, nutrient transport, apoptosis and oxidative stress-related genes in SCNT-DW4 placentas were erroneous compared with those in SCNT-SO4 and AI-SO4 placentas, which both had similar gene expression patterns. These results indicate that birth weight, umbilical status, placental parameters, placental morphology and gene expression were associated with neonatal death of cloned piglets. The high loss of cloned piglets during neonatal age may be caused by severe deficiency of extra-embryonic development during prenatal stage.

The relationship between trace mineral concentrations of amniotic fluid with placenta traits in the pregnancy toxemia Ghezel ewes

ObjectiveThis study was conducted to investigate the trace mineral concentrations (Mg, Se, Zn, Cu and Fe) in amniotic fluid (AF) in 40 pregnancy toxemia Ghezel ewes at the time of parturition phase and its association with placental traits. MethodsAnimals were treated with controlled internal drug release for 14 d and injected 400 IU pregnant mare serum gonadotropin at the time of controlled internal drug release removal. After the detection of estrus by use of teaser rams, ewes were hand-mated. Ewes were classified as having subclinical pregnancy toxemia on the basis of beta-hydroxy butyrate (BHBA) results (BHBA > 0.86 mmol/L). ResultsThe overall mean AF traces of mineral concentrations were 3.13 ng/mL, 22.1 μg/dL, 134.7 μg/dL, 122.5 μg/dL and 166.6 μg/dL, respectively. There was a significant positive correlation between placental efficiency and Zn concentration in AF ewes (r = 0.633, P < 0.01), while the relationship was significantly negative between total volume of amniotic fluid and Fe concentration in AF ewes (r = −0.717, P < 0.01). In this research, no relationship between Se, Mg and Cu trace minerals was observed in AF ewes with placental traits ewes. Results of laboratory analyses demonstrated no relationship between BHBA concentrations and placental traits (P > 0.01), except for placental weight (r = 0.808, P < 0.01). Also, no significant correlation was detected between BHBA with the above trace minerals. ConclusionsOverall, determinations of these trace minerals in the AF ewes could have been used to obtain information on nutritional and reproductive status for the diagnosis of pregnancy toxemia in Ghezel ewes.

Positive and negative gestational handling influences placental traits and mother-offspring behavior in dairy goats

Dairy animals are subjected to a number of potential stressors throughout their lives, including daily interactions with humans. The quality of these interactions may have direct consequences for the animal undergoing the experience, but if such events occur during gestation it may also affect the developing fetus. This study examined the effects of differential handling during mid-gestation in 40 twin-bearing Saanen×Toggenburg primiparous goats. Between days 80 and 115 of gestation (gestation=150days), goats were subjected to aversive (AVS, n=13), gentle (GEN, n=13) or minimal (M, n=14) handling protocols for 10minute periods twice daily. The control (M) group did not receive handling treatments and all goats received normal husbandry procedures outside treatment periods. Salivary cortisol measured during the treatment period was higher in AVS goats (mean cortisol (sem) in pg/μl: AVS: 176.7 (18.2), GEN: 119.6 (11.1), M: 126.5 (13.7); P=0.007). Data collection was focussed on mother-offspring behaviors 2h post-partum, placental morphology and colostrum quality. AVS goats were the only treatment group to suffer fetal loss (16% loss vs 0% in GEN and M, P=0.05). Treatment also influenced placental morphology with a tendency for fewer cotyledons evident in placentae from the aversive treatment (AVS: 87.9 (7.8), GEN: 107.1 (7.9), M: 112.1 (9.3), P=0.093), and significantly fewer medium sized cotyledons (AVS: 67.6 (7.8), GEN: 89.3 (6.4), M: 84.3 (5.4), P=0.042). GEN goats displayed more grooming and nosing behaviors towards their young during the first 2h post-partum (grooming: GEN: 89.3% (7.1), AVS: 72.6% (7.7), M: 63.4% (9.0), P=0.045; nosing frequency: GEN: 58.8 (12.5), AVS: 28.6 (11.1), M: 34.7 (6.5), P=0.021). There was an overall trend for kids from mothers experiencing the AVS treatment to take longer to stand, reach the udder and suck compared to kids from GEN and M treatment groups. Treatment significantly affected latency to perform play behavior, with kids from AVS goats taking on average 25min longer to play for the first time than kids from GEN and M treatment groups (P<0.001). The results show that handling during gestation affects placental morphology, fetal survival and post-partum maternal behaviors, and influences kid behavioral development. Such results have important animal welfare implications, demonstrating that negative handling of pregnant females results in poorer placental quality with potential for fetal loss. It also demonstrates the beneficial effects of positive handling on enhancement of maternal behaviors.

Poor placental traits reduce kid birth weight in young Saanen dams in the first parity

Placental characteristics are the most important indicators of fetal growth and development that influence kid vitality. The aim of this study was to examine the effect of maternal parity on placental characteristics and birth-related traits in Saanen goats. The experiments were conducted on 41 singleton-bearing Saanen does, ranging from 1 to 4 years of age and classified according to first, second, and third parities. Birth weight, placental weight, placental efficiency, and cotyledon density were influenced by parity (P < 0.05). First-parity does had kids with significantly (P < 0.05) lower birth and placental weights than does of other parities, while they had significantly higher (P < 0.05) placental efficiency and cotyledon density. First-parity does had fewer (P < 0.05) large and total cotyledons than third-parity does. Cotyledon dimensions varied among parities (P < 0.05), while average cotyledon surface area and cotyledon efficiency were the lowest in the first-parity does (P < 0.05). The results suggest that younger dams in the first parity may alter placental characteristics and fetal development, resulting in a reduced birth weight from singleton gestations.

Polymorphisms of osteopontin gene and their association with placental efficiency and prolificacy in goats

In this study, we investigated the polymorphisms of Caprine osteopontin (OPN) gene and their association with placental traits and prolificacy in goats. The placental and reproductive traits of 171 litters on three goat breeds with different prolificacy (Dazu Black, n = 94; Lezhi Black, n = 27; Hexi Cashmere, n = 50) were evaluated. The polymorphisms in the 5′ promoter and exon 7 of OPN gene were detected by PCR-SSCP methods. Their association was further achieved by using least squares means. It showed that the litter size, litter and placenta weight for Dazu Black and Lezhi Black goats were higher significantly than those of Hexi Cashmere goats (P < 0.01). However, the placental efficiency was not significantly different (P > 0.05). Hexi Cashmere does have more cotyledons in placental than that of Dazu Black and Lezhi Black does (P < 0.01). There were only two genotypes (nominated AA and AB) detected whether by the 5′ promoter primer pairs or by exon 7 of OPN gene. They were associated with litter number, with a trend of AA > AB. At the exon 7 locus, the Dazu Black does with genotype AA had 0.88 more litter numbers than those with genotype AB (P < 0.05). It suggested that OPN gene could be a potential candidate gene on goat prolificacy.

The relationship between progesterone and biochemical constituents of amniotic fluid with placenta traits in Iranian crossbred ewes (Arkhar-Merino×Ghezel)

ObjectiveTo determine the values of amniotic fluid (AF) progesterone and biochemical constituents and its associated placenta traits in Iranian crossbred ewes (Arkhar-Merino×Ghezel). MethodsSixty ewes (2-5 years old, weighing 40-50 kg) were treated with controlled internal drug release induced 30 mg progesterone for 14 d and were injected with 400 IU pregnant mare serum gonadotropin at the time of CIDR withdrawal. After the detection of estrus, ewes were hand-mated. After expelling of each fetus accompanied by fetal membranes, 10 mL AF was taken from fetal sac for spectrophotometer methods (glucose, urea, creatinine, total protein, cholesterol, triglycerides, calcium and phosphorus) and radioimmunoassay (progesterone) analysis. ResultsResults indicated that there were highly positive correlations between placental efficiency and cotyledon density (r=0.764, P<0.01), and negative correlation between placental weight (PW) with the total volume amniotic fluid (TVAF) (r=−0.872, P<0.01). A positive relationship was calculated between TVAF with total protein and creatinine (r=0.418, P<0.01 and r=0.639, P<0.05, respectively). However, the correlation between the glucose and PW, cotyledon length and calcium were significantly positive (r=0.704 and r=0.712; P<0.01, respectively). The findings of this study demonstrated that there were no relationships between progesterone concentrations and placental traits (P>0.01), except for PW (r=0.665). ConclusionsIn conclusion, the significant correlation between the AF biochemical and progesterone with placental traits for the above-mentioned metabolites suggests that metabolic changes in AF levels will reflect the condition in the AF.

Relationship between placental traits and birth related factors in Damascus goats

The relationship between placental traits and litter related factors of Damascus goats were investigated. In total, 39 Damascus goats of same age were used in the study. One-way ANOVA was used for statistical comparison and a Poisson regression analysis was used to determine the effect of litter size and sex on cotyledon number. Pearson correlation co-efficient was used to determine the relationships between variables. Cotyledon efficiency (CE), cotyledon number (CN), number of small, medium and large cotyledons, cotyledon density (CD), individual cotyledon surface area and litter weight have been determined significant for litter size (p<0.05). A positive correlation was revealed between placental weight (PW) individual cotyledon weight (ICW) (r=0.88, P<0.05), cotyledon weight (CW) (r=0.64, P<0.05), large cotyledons number (LCN) (r=0.54, P<0.05), also between birth weight (BW) and PW (r=0.47, P<0.05) and litter weight (LW) (r=0.38, P<0.01). CW was negatively correlated with CD (r=−0.55, P<0.05) and placental efficiency (PE) (r=−0.82, P<0.05). PW and PE were found highest in twin births. Single kids at an average of 4704±147g were born heavier than twin kids (4315±333g). While CW did not differ between single and twin births ICW was much higher (double) for twins. Sex had no effect on CN (P>0.05); however litter size was found significant according to Poisson regression results. The most important finding of this study was the significant variance in cotyledon numbers between single and twin births. There was a notable increase of small and medium cotyledon numbers and a significant decrease of large cotyledons for single births while the exact opposite occurred for twin births. This significant correlation initiated to a new parameter for measuring the efficiency of placental exchange.

Placental traits and their relation with birth weight in Meriz and Black goats

At a commercial farm of goat, Duhok province, Kurdistan Region, Iraq, the relationship between placental traits and birth weight of kids together with some factors affecting these traits were investigated in this study. A total of 79 foetal placental delivered at normal kidding were collected from Black goat (n=33) and Meriz (n=46). The results revealed that neither breed of goat nor sex had a significant effect on all placental traits. A positive correlation between birth weight (BW) of kids and each of placental efficiency (PE) ( r =0.38; P ≤0.01), placental weight (PW) ( r = 0.01, P ≥0.05), cotyledon weight (CW) ( r = 0.08, P ≥0.05) was found, and a non significant negative correlations was noticed between BW and each of cotyledon number (CN) ( r = -0.05, P ≥0.05), and cotyledon density (CD) ( r = -0.12, P ≥0.05). PW is positively correlated with the CW ( r = 0.73, P ≤0.01) and CN ( r = 0.41, P ≤0.01) and negatively correlated with PE ( r = 0.80, P ≤0.01) and CD ( r = -0.46, P ≤0.01). Results showed a significant positive correlation between placental efficiency and each of birth weight of kids and cotyledon density.

Relationship between placental traits and maternal intrinsic factors in sheep

The relationship between maternal intrinsic factors and placental traits was investigated on three Southern Mediterranean breed of sheep; Cukurova Assaf (CA), Cukurova (C) and Cukurova Meat Sheep (CMS). The effect of parity and birth type were also considered in the study as a potential influencing factor. Our hypothesis was to show that while differences in placental traits between breed, parity and birth type affected lamb condition and survivability, its correlation to maternal intrinsic behavioral factors may also be a strong indicator. The study found breed related differences of maternal behavioral factors and also showed significant correlation of these behavioral patterns to various placental traits. It confirmed earlier findings that parity played a major role in the refinement of these behavioral patterns. Significant differences in birth weight (P<0.05), placental weight (P<0.05), number of cotyledons (P<0.01) and cotyledon length (P<0.05) was seen between breeds. Cotyledon weight (P<0.05), width (P<0.01) and length (P<0.05) were found to differ by parity. Breed and parity interaction significantly influenced cotyledon quantity. While we detected breed specific differences in relation to maternal intrinsic factors we also noticed significant variance within breeds to these behavioral patterns when linked to placental traits. Further study is required on the correlation between placental traits and postnatal behavior on not just the ewes but also on their lambs. This could have a significant bearing on how producers manage and maximize lamb survivability.

Placental traits and maternal intrinsic factors affected by parity and breed in goats

The relationship between placental traits and maternal intrinsic factors of Saanen, German Fawn and Damascus goats was investigated. Data was collected from 93 goats. The results of the study demonstrated that there were positive correlations between placental weight (PW) and cotyledon number (CN) ( r = 0.498, P < 0.01), cotyledon weight (CW) ( r = 0.880, P < 0.01), cotyledon density (CD) ( r = 0.538, P < 0.01), cotyledon width (CWI) ( r = 0.500, P < 0.01) cotyledon length (CL) ( r = 0.414, P < 0.01) and cotyledon density (CD) ( r = 0.278, P < 0.05). CN was negatively correlated with placental efficiency (PE) ( r = −0.421, P < 0.01) and CD ( r = −0.325, P < 0.05). While expulsion of placenta, right teat length and cotyledon length were affected by parity of doe ( P < 0.05) birth weight (BW), CN, right teat diameter (RTD), left teat diameter (LTD), CD, and CL were affected by breed ( P < 0.01). Breed × parity was found significant both for expulsion time of placenta and left teat length (LTL) ( P < 0.05). Damascus goats had a significantly longer duration of licking and grooming events than others. Saanen was more likely to require birth assistance compared to the German Fawn.

Effects of antioxidant vitamins on newborn and placental traits in gestations at high altitude: comparative study in high and low altitude native sheep

The present study evaluated the hypothesis that the effects of hypoxia on sheep pregnancies at high altitude (HA) are mediated by oxidative stress and that antioxidant vitamins may prevent these effects. Both HA native and newcomer ewes were maintained at an altitude of 3,589 m during mating and pregnancy. Control low altitude (LA) native ewes were maintained at sea level. Half of each group received daily oral supplements of vitamins C (500 mg) and E (350 IU) during mating and gestation. Near term, maternal plasma vitamin levels and oxidative stress biomarkers were measured. At delivery, lambs were weighed and measured, and placentas were recovered for macroscopic and microscopic evaluation. Vitamin concentrations in supplemented ewes were two- or threefold greater than in non-supplemented ewes. Plasma carbonyls and malondialdehyde in non-supplemented ewes were consistent with a state of oxidative stress, which was prevented by vitamin supplementation. Vitamin supplementation increased lamb birthweight and cotyledon number in both HA native and newcomer ewes, although placental weight and cotyledon surface were diminished. Placentas from vitamin-supplemented HA ewes were similar to those from ewes at sea level, making these placental traits (weight, number and diameter of cotyledons) similar to those from ewes at sea level. Vitamin supplementation had no effect on LA pregnancies. In conclusion, supplementation with vitamins C and E during pregnancy at HA prevents oxidative stress, improving pregnancy outcomes.

Placentation and Maternal Investment in Mammals

The mammalian placenta exhibits striking interspecific morphological variation, yet the implications of such diversity for reproductive strategies and fetal development remain obscure. More invasive hemochorial placentas, in which fetal tissues directly contact the maternal blood supply, are believed to facilitate nutrient transfer, resulting in higher fetal growth rates, and to be a state of relative fetal advantage in the evolution of maternal-offspring conflict. The extent of interdigitation between maternal and fetal tissues has received less attention than invasiveness but is also potentially important because it influences the surface area for exchange. We show that although increased placental invasiveness and interdigitation are both associated with shorter gestations, interdigitation is the key variable. Gestation times associated with highly interdigitated labyrinthine placentas are 44% of those associated with less interdigitated villous and trabecular placentas. There is, however, no relationship between placental traits and neonatal body and brain size. Hence, species with more interdigitated placentas produce neonates of similar body and brain size but in less than half the time. We suggest that the effects of placental interdigitation on growth rates and the way that these are traded off against gestation length may be promising avenues for understanding the evolutionary dynamics of parent-offspring conflict.

Comparison of placental traits and their relation to litter size and parity weight in sheep

The relationships between genotype and placental traits, parity and litter weight (LW), and factors affecting these characteristics were investigated in this study. In total, 112 ewes (Romanov crossbred and local breeds) were utilized. One-way ANOVA was used for statistical comparison, and a Pearson correlation was used to determine the relationships between the variables. Significant differences in parity weight within genotype and breed have been determined. A negative correlation was revealed between placental weight (PW) and placental efficiency (r = -0.743, P < 0.01; and r = -0.732, P < 0.01). There was no relationship between litter sex and placental traits. Birth type had a significant effect on PW (P < 0.05), and significant differences within sex-birth type interactions occurred (P < 0.05). The results of the present study have shown a positive correlation between cotyledon density and placental efficiency among all genotypes and breeds that were used in the study. In conclusion, it has been determined that placental traits were affected by LW and Romanov crossbreed ewes had greater PW than local breeds. Further studies are required to investigate the relationship between parity and placental traits in sheep.

Investigating the behavioural and physiological indicators of neonatal survival in pigs

Survival is reduced in low birth weight piglets, which display poor thermoregulatory abilities and are slow to acquire colostrum. Our aim was to identify additional behavioural and physiological indicators of piglet survival incorporating traits reflective of both the intrauterine and extrauterine environment. Data were collected from 135 piglets from 10 Large White x Landrace sows to investigate which physiological measurements (e.g. individual placental traits), and which behavioural measurements (e.g. the quantification of piglet vigour), were the best indicators of piglet survival. Generalised linear models confirmed piglet birth weight as a critical survival factor. However, with respect to stillborn mortality, piglet shape and size, as measured by ponderal index (birth weight/(crown-rump length)(3)), body mass index (birth weight/(crown-rump length)(2)), respectively, and farrowing birth order were better indicators. With respect to live-born mortality, postnatal survival factors identified as crucial were birth weight, vigour independent of birth weight, and the latency to first suckle. These results highlight the importance of the intrauterine environment for postnatal physiological and behavioural adaptation and identify additional factors influencing piglet neonatal survival.