Increased Litter Size Research Articles

The replacement gilt: Current strategies for improvement of the breeding herd

The efficiency of swine production is affected by many factors. One of the most economically important factors is gilt reproductive performance. To achieve satisfactory results in breeding, both environmental and genetic factors must be monitored and constantly improved. For many years, intensive selection in the swine industry for increased carcass muscle to fat ratio has led to deterioration in some reproductive traits (eg, less favorable development of the reproductive system in gilts, problems with fertilization, large litters but tiny piglets). In recent years, many producers have focused on increasing litter size and weaning weights of piglets in addition to an emphasis on increasing sow productive life span. In replacement gilts, the systematic evaluation of both reproductive and structural soundness is of paramount importance. The main aim of this review is to summarize the current criteria for selecting replacement gilts.

Effects of Nesting Material on the Toxicologic Assessment of Cyclophosphamide in Crl:CD1(ICR) Mice.

The provision of nesting material benefits mice by reducing cold stress, improving feed conversion, increasing litter size, and improving adaptive immunity. The effects of toxins are sensitive to environmental changes, and the introduction of novel items can alter results in some toxicologic studies. We hypothesized that nesting material would reduce stress and positively alter immunologic parameters in Crl:CD1(ICR) mice, thus changing typical results from a well-studied immunomodulating drug, cyclophosphamide. A 13-wk study assessed the following treatments in a factorial design (n = 4; 32 cages total): nesting (0 or 10 g) and drug (50 mg/kg cyclophosphamide or 10 mL/kg saline; IP weekly). Detailed examinations and body weights were recorded weekly, and nests were scored twice weekly. Fecal pellets were collected at 0, 4, 6, and 12 wk for analysis of corticosterone metabolites. At study termination, clinical pathology and immune parameters were collected, a necropsy performed, and lymphoid organs and adrenal glands were submitted for histopathology. All expected results due to cyclophosphamide were observed. Nesting reduced the proportion of mice with piloerection, and body weights were highest in saline-nested male mice. No differences in hematology, clinical chemistry, or absolute lymphocyte counts were observed. Corticosterone metabolites in all nested groups were not different from baseline levels but all nonnested groups had higher levels than baseline. Nested cyclophosphamide-treated groups had significantly lower corticosterone levels than nonnested cyclophosphamide-treated groups. This study illustrates that nesting material does not alter the results of a standard toxicology study of cyclophosphamide but alleviates study-related stress and improves mouse welfare.

SEXUAL RECEPTIVITY, REPRODUCTIVE HORMONES AND PERFORMANCE TRAITS OF AGING FEMALE RABBITS AS AFFECTED BY DIFFERENT SOURCES OF UNSATURATED FATTY ACIDS

Sixty V-lines doe rabbits, 24 months of age weighing 3244±58.9 g, which had low conception rate and repeated refuse of mating were used. Rabbits were randomly divided into five equal treatment groups and orally administered with 3 ml of different sources of oil/doe/day, for eleven consecutive days prior to insemination as follows: group 1 sterilized water and served as control (C), group 2 sesame oil (Ses), group 3 linseed oil (Lin), group 4 sunflower oil (Sun), group 5 mixture oil (Mix) containing equal portions of Ses, Lin and Sun oils. Estradiol (E217-β), progesterone (P4) and prostaglandin (PGF2α), sexual receptivity of does, fertility rate, litter size and bunny weight at birth were measured. Results revealed that: 1- All treated groups represented significant (P≤0.01) increase of hormonal profile (E217-β, P4 and PGF2α), sexual receptivity, fertility rate, litter size and bunny weight at birth compared to the control group. 2- Aged doe rabbits supplemented with Ses and Sun oils recorded highest concentrations of E217β and PGF2α and decrease of P4 than Lin and Mix oils or the control groups. 3-Sexual receptivity and fertility rate were improved (P≤0.01) for groups supplemented with Ses and Sunoils compared with other groups. 4- Litter size and bunny weight at birth were significantly (P≤0.01) increased for groups supplemented with Linand Mix oils compared with other groups. Conclusively, supplementing the aged doe rabbits with Ses, lin and Sun oils or their mixture for 11 consecutive days perior insemination could be beneficial for improving estradiol and prostaglandin hormone with subsequent improvement of does receptivity, litter size and bunny weight combined with progesterone reduction

Evaluación de una vacuna de ADN y su péptido recombinante contra inhibina alfa (165-300) sobre la respuesta inmune y fertilidad en ratones

Se evalúo la vacuna de ADN (INHA-DNA) y su péptido recombinante (INHA-rec) contra inhibina alfa (INHA) sobre la respuesta inmune y la fertilidad en ratones. Dieciséis ratones Balb/c fueron divididos en dos grupos, 8 cada uno. Bajo un esquema de inmunización prime boost heterólogo, un grupo fue inoculado vía intramuscular (IM) con 100 µg de INHA-DNA y 14 d después con 100 µg de INHA-rec. El grupo control recibió solución salina. Se aparearon las hembras en dos ocasiones. Posterior al primer parto se dio un refuerzo vía IM con ambos inmunógenos (100 µg INHA-DNA + 100 µg INHA-rec). La inmunización con 100 µg de INHA-DNA y INHA-rec indujo altos niveles de anticuerpo anti INHA, mayor tamaño y peso de camada (P<0.05) comparados con el control. La fertilidad promedio fue similar entre los tratados (67%) y control (60%). En conclusión, la vacuna de ADN y su antígeno recombinante es capaz de inducir títulos de anticuerpos contra INHA incrementando el tamaño de camada, sin un efecto negativo sobre la fertilidad en ratones.

Estimation of direct and maternal genetic parameters for individual birth weight, weaning weight, and probe weight in Yorkshire and Landrace pigs.

As a result of selecting for increased litter size, newborn piglets are being born lighter and have a lower chance of survival. Raising fewer pigs to market weight would have a negative impact on the industry and farmer profitability; thus, understanding the genetics of individual growth performance traits will determine whether these traits will play an important role in pig breeding schemes. This study aimed to estimate genetic parameters for individual birth weight (BW), weaning weight (WW), and probe weight (PW) in Canadian-purebred Yorkshire and Landrace pigs. PW is a live weight taken at the time of the ultrasound measurements, when pigs weigh about 100 kg. Data were collected from 2 large and related breeding herds from 2003 to 2015. Four linear animal models were used, which included the following: Model 1-direct additive genetic effect; Model 2-direct additive genetic and maternal genetic effect; Model 3-direct additive genetic and common litter effect; and Model 4-direct additive genetic, maternal genetic, and common litter effect. The model which included all 3 random effects (Model 4) was determined to be the best fit to the data. Low to moderate direct heritability estimates were observed as follows: 0.15 ± 0.03 for BW, 0.04 ± 0.01 for WW, and 0.33 ± 0.03 for PW for the Yorkshire breed; and 0.05 ± 0.01 for BW, 0.01 ± 0.01 for WW, and 0.27 ± 0.03 for PW in the Landrace breed. As expected, the direct heritability estimates increased with age as a result of decreased maternal influence on the trait. Bivariate animal models were also used to estimate genetic and environmental correlations between traits. Strong direct genetic correlations were observed between BW and WW in both breeds. Based on the estimates of genetic parameters, individual BW could be evaluated and considered in breeding programs aiming to increase BW and improve subsequent performance. Different selection emphasis could also be applied on direct and maternal additive genetic effects on BW to optimize the breeding programs and improve selection efficiency.

The association of serum β-hydroxybutyrate concentration with fetal number and health indicators in late-gestation ewes in commercial meat flocks in Prince Edward Island

Late-gestation ewes are susceptible to ketonemia resulting from high energy requirement for fetal growth during the last few weeks of pregnancy. High lamb mortality is a possible consequence of effects of ketonemia on both ewes and lambs. Determining risk factors to ketonemia is a fundamental step to identify ewes at risk, in order to avoid losses caused by ketonemia. Serum β-hydroxybutyrate (BHBA) concentrations of 384 late-gestation ewe samples were determined. Physical examinations, including body condition, FAMACHA© and hygiene scoring, were performed. Udders and teeth were also examined. Fecal floatation was performed to detect gastrointestinal helminth eggs of the ewe fecal samples. General feeding management practices and season at sampling were recorded. Litter sizes were retrieved from lambing records. Factors associated with log serum BHBA concentration were determined using a linear mixed model, with flock and lambing groups as random effects. The mean serum BHBA concentration was 545.8 (±453.3) μmol/l. Ewes with a body condition score (BCS) of 2.5–3.5 had significantly lower log BHBA concentrations than ewes with a BCS of ≤2.0, by 19.7% (p = 0.035). Ewes with a BCS of >3.5 had a trend toward higher log BHBA concentrations compared to ewes with a BCS of 2.5–3.5. Ewes with a FAMACHA© score of 3 had significantly higher log BHBA concentrations than ewes with a FAMACHA© score of 1 or 2, by 12.1% (p = 0.049). Ewes in which gastrointestinal helminth eggs were detected had significantly higher log BHBA concentrations than ewes in which helminth eggs were not detected, by 12.3% (p = 0.040). An increased litter size was associated with higher log BHBA concentration (p ≤ 0.003), with the log BHBA concentrations of ewes having twins, triplets, and quadruplets or quintuplets were higher than those of ewes having singleton by 19.2%, 30.4%, and 85.2%, respectively. Season at sampling confounded the association between log BHBA concentration and FAMACHA© score, and therefore was retained in the final model even though it was not statistically significant. Intra-class correlation coefficients at the flock and lambing group levels were 0.14 and 0.32, respectively.

Leucocyte profile and offspring production of guinea pig (Cavia cobaya) given Anredera cordifolia leaf extract

The objective of this study was to determine leucocyte and offspring production of guinea pig (Cavia cobaya) giving Anredera cordifolia leaf extract. Materials used were female 16 heads of guinea pig with body weight of 425g. The treatments were an extract of A. cordifolia leaf at doses of 0, 10, 50 and 90 mg/head, designated as T0, T1, T2 and T3, respectively. A. cordifolia leaf extract was administered orally from 10 days prepartum to 10 days postpartum. Blood was taken at 10 days prepartum and 10 days postpartum. Total birth of the offspring was observed. Data were analyzed by analysis of variance and if there was effect of treatment, then continued with Duncan multiple range test and Chi-Square test for fetal production between the given A. cordifolia leaf extract and control. The result showed that there was no significant difference for 10 days prepartum after addition of A cordifolia leaf extract treatment. The postpartum treated showed a total 50 mg/head level increaed for monocytes than that of level 0, 10 and 90 mg/head. Ten days postpartum treatment showed the total increase for leucocyte and monocytes total were 50 and 90 mg/head, respectively compared to 10 mg/head level. Total lymphocyte of 90 mg/head increased compared to level 10 and 50 mg/head. The highest total neutrophil as found at level of 50 mg/head which increased compared to the level of 0 and 10 mg/head. ProvisioningA. cordifolialeaf extract at doses level of 50 and 90 mg/head could increase litter size (P<0.05; χ2=9.267) and decreased offspring mortality (P<0.05; χ2=6.4). In conclusion, by giving 50 mg/head A. cordifolia leaf extract could increase leucocyte profile and offspring production of guinea pig.

Di(2-Ethylhexyl) Phthalate Exposure During Prenatal Development Causes Adverse Transgenerational Effects on Female Fertility in Mice.

Di(2-ethylhexyl) phthalate (DEHP) is a ubiquitous environmental toxicant and endocrine disrupting chemical, but little is known about its effects on female reproduction. Thus, we tested the hypothesis that prenatal exposure to DEHP accelerates the onset of puberty, disrupts estrous cyclicity, disrupts birth outcomes, and reduces fertility in the F1, F2, and F3 generations of female mice. Pregnant CD-1 mice were orally dosed with corn oil (vehicle control) or DEHP (20 and 200 µg/kg/day and 500 and 750 mg/kg/day) from gestation day 10.5 until birth. F1 females were mated with untreated males to obtain the F2 generation. F2 females were mated with untreated males to produce the F3 generation. In all generations, the onset of puberty, estrous cyclicity, select birth outcomes, and fertility-related indices were evaluated. In the F1 generation, prenatal DEHP exposure (200 µg/kg/day) accelerated the onset of puberty, it (200 µg and 500 mg/kg/day) disrupted estrous cyclicity, and it (20 and 200 µg/kg/day) decreased fertility-related indices. In the F2 generation, ancestral DEHP exposure (500 mg/kg/day) accelerated the onset of puberty, it (20 and 200 µg/kg/day) disrupted estrous cyclicity, it (20 µg and 500 mg/kg/day) increased litter size, and it (500 mg/kg/day) decreased fertility-related indices. In the F3 generation, ancestral DEHP exposure (20, 200 µg, and 500 mg/kg/day) accelerated the onset of puberty, it (20 µg/kg/day) disrupted estrous cyclicity, and it (750 mg/kg/day) decreased female pup anogenital index. Collectively, these data indicate that prenatal DEHP exposure causes female reproductive problems in a multigenerational and transgenerational manner.

Can body nosing in artificially reared piglets be reduced by sucking and massaging dummies?

Selection for hyper-prolific sows has substantially increased litter size. Consequently, the number of piglets in a litter may exceed the number of functional teats. To solve this problem, surplus piglets may be removed from the sow 2 days after birth and raised artificially. However, these piglets show increased levels of oral behaviours, such as belly nosing, directed at other piglets. This behaviour resembles massaging and sucking at the sow’s udder and thus is considered to be redirected suckling behaviour. The present study investigated whether oral behaviour directed at piglets can be reduced in artificially reared piglets by providing them with sucking and massaging dummies. In a two-by-two between-group factorial design, the artificial rearing pens were equipped with one of four treatments: a sucking dummy, a massaging dummy, a combined sucking–massaging dummy, or no dummy. The behaviour of 126 piglets (in 21 groups of 6 piglets) was scored from video by continuous focal observation lasting 90 min per piglet each on days 4 and 18 after introduction to the artificial rearing system. Data were analysed using linear mixed-effects models. Body nosing (composed of belly nosing and nosing on any other body part) increased from day 4 to 18 in all treatments, but piglets provided with a combined sucking–massaging dummy showed the smallest increase. Piglets spent more time nosing the combined dummy than the sucking or the massaging dummy. However, there was no causal inverse relationship between the duration of body nosing and dummy nosing. All but one piglet showed body nosing at least once. Resting, play-fighting, or oral manipulation of piglets (other than body nosing), dummies, and pen equipment were hardly affected by the treatments. Piglets with a combined dummy tended to have a longer average resting bout duration compared with piglets in other treatments. In conclusion, only the combined sucking–massaging dummy was effective in reducing the increase in body nosing over time. However, this reduction was rather small in absolute terms and the combined dummy did not prevent body nosing. The tested dummies were thus not successful in eliminating the redirected oral behaviour in artificially reared piglets.

Testicular transcriptional signatures associated with high fertility.

Factors of high fertility are poorly described. The majority of transgenic or knockout models with a reproductive phenotype are subfertile or infertile phenotypes. Few genotypes have been linked to improved reproductive performance (0.2%) or increased litter size (1%). In this study, we used a unique mouse model, fertility line FL1, selected for 'high fertility' for more than 170 generations. This strain has almost doubled the number of littermates as well as their total birth weight accompanied by an elevated ovulation rate and increased numbers of corpora lutea compared to a randomly mated and unselected control line (Ctrl). Here, we investigate whether the gonadal tissue of FL1 males are affected by 'co-evolution' after more than 40 years of female-focused selection. Using microarrays, we analysed the testicular transcriptome of the FL1 and Ctrl mice. These data were also compared with previously published female gonadal transcriptional alterations. We detected alterations in testicular gene expression, which are partly associated with female reproductive performance. Thus, female-focused selection for litter size has not only affected the female side, but also has been manifested in transcriptional alterations on the male gonadal organ. This suggests consequences for the entire mouse lines in the long run and emphasizes the perspective of inevitably considering both genders about mechanisms of high fertility.

Effect of genotype and some non-genetic factors on weaning weight in rabbits

The rabbit meat producers have a strong desire to improve productivity in order to maximize on financial gains. There has been a deliberate move to target improved weaning weight, which is thought to be a critical component in influencing total meat yield and economic returns. However, it has been acknowledged that weaning weight is partly influenced by individual kit genetic potential at the same time its overwhelmed by various non genetic factors. In this respect, weaning weights a complex character which reflects the influence of many biological processes namely fertility, maternal instinct, growth and viability. For the purpose of increasing production, it is reasonably to suggest that the complex inter-relationship among known various non genetic factors that influence weaning weight and the degree of their interactive effects need to be ascertained and understood in different production systems. While, genotype is a major contributor to weaning weight, environmental, nutritional and management practices also play significant roles in influencing weaning weight. There are several known environmental factors that influence weaning weight and these include feeding practices, birth weight, parity order, sex of kits, management, etc. The rabbit producers’ attention to the aforementioned factors is likely to improve weaning weight at enterprise level. It is important to note that selection for increased litter size have an adverse effect on average litter birth weight which subsequently reflects on weaning weight. The enhanced prolificacy in does has resulted in an increase in within litter variation and a larger number of kits born light. From the farmer’s performance point of view, genetic diversity utilization in crossbreeding has been the focus in improving weaning weight in commercial rabbit meat production. However, the complementary role played by nutritional status in optimization of performance in selected genotypes has been tremendous in the past two decades. Crossbreds have performed at levels consistent with different targeted rabbit meat market expectations. Generally, it is pronounced that improved nutritional regime and patterns for lactating does and their suckling kits had a positive effect on weaning weight. On the other hand, unbalanced parity structure and distribution in rabbit enterprise results in unreasonable variation in weaning weight, which impacts negatively on subsequent kits management after weaning. The purpose of this review is to discuss the influence of genotype and some non-genetic factors (litter size, birth weight, parity) on weaning weight in rabbits.

Factors influencing does milk production and their implication for kit performance in rabbits

Rabbit milk yield and chemical composition is determined by various factors. Growth rate and body weight gain are good indicators of kitsdoe’s maternal behavior, especially in milk production. Generally, it is pronounced that growth and survival of kits towards weaning is the most important stage related to does milking potential. However, it is important to note that lactation curves vary with breed, notwithstanding milk production being influenced by various factors. Clearly, it has been observed that apart from genotype being a dominant factor in influencing milk production in rabbits, there are other factors such as nutrition, parity, stage of lactation, litter size etc. which have also been implicated. In this aspect, appropriate knowledge on factors that influence does milking capacity is essential for improved performance in rabbits. Provision of adequate nutritional requirements of nursed kits through dam’s milk is essential for maximum growth, development and survival. In the early stage of growth until weaning, does milk is the exclusive source of nutrients to support the pertinent needs for maintenance and growth in rabbits. The accelerated growth preceding weaning can be ascribed to the doe’s energy rich milk that is significant in both fat and protein and low lactose. An increase in milk intake, can improve kits growth traits and may also transcribe to heavier final market weight and financial gains. It is reasonable to suggest that to enhance kits nutritional intake, the mother should produce adequate milk. On the other hand, milk production increases with increased litter size, while high total milk yield is registered in winter followed by autumn. Milk production increase firmly during the seven parity and decline from that time forward. Crossbreeding promote favorable and positive heterotic influence on milk yield and composition. There is a predictable positive correlation of does milking capacity and productive traits. The purpose of this review is to discuss the factors that influence milk production in does and their implication for rabbit performance.

Sow level risk factors for early piglet mortality and crushing in organic outdoor production

Piglet mortality is a major problem in organic pig production affecting both farm economy and animal welfare. Knowledge is scarce on the risk factors of piglet mortality in Danish commercial organic pig production. The objectives of this study were to evaluate season, litter size, parity, sow body condition and stillborn littermates as risk factors for early piglet mortality and crushing of liveborn piglets from parturition until castration at day 3 to 5 postpartum (pp). The study was conducted over a 1-year period in nine commercial Danish organic pig herds practicing outdoor farrowing all year round. Data included recordings on 3393 farrowings with 50 284 liveborn piglets of which 14.8% died before castration. A subset of the dead piglets were collected and necropsied to identify crushed piglets. The average number of liveborn piglets per litter was 14.8 (SD=3.7) and the average time from parturition until castration was 4.1 (SD=1.7) days. A negative binomial regression analysis was used to model the effect of the predictive variables on the early piglet mortality accounting for different time periods from parturition to castration. An increase in maternal body condition score (BCS) and parity significantly increased the risk of dying between parturition and castration. Early mortality was found to be lowest during spring (March to May) and highest during summer (June to August). Being born into a litter with one or more stillborn littermates increased the risk of early mortality. The risk factors for crushing of piglets were evaluated using a logistic analysis. A significant effect of parity and litter size was found where the odds of at least one piglet in a litter with mortality was diagnosed as crushed increased with increasing parity and litter size. In conclusion, being born during summer (June to August), high parity and maternal BCS and stillborn littermates were found to be risk factors for piglet mortality between parturition and castration. In addition, parity and increasing litter size were found to be risk factors for crushing of piglets in litters with mortality.

Assessment of viability of new born piglets using an adjusted APGAR score

Since decades pig breeding goals have mainly focused on prolificacy. However, large litters can have implications on piglets’ and sows’ welfare. Due to increased litter size viability of piglets may decrease, leading to a higher number of stillborn piglets and increased suckling piglet mortality. Piglet viability can be assessed using an adjusted APGAR score. This score measures in the new born piglet indicators crucial for the ability to survive. So the aim of this paper is to investigate the main effects on piglet viability by using an adjusted APGAR score. For this purpose, 25 sows and 404 born piglets were assessed using an adjusted APGAR scoring system. Every live born piglet was evaluated directly after birth regarding the parameters skin colour, umbilical cord condition, latencies to respiration, first movement, first attempt to stand up and first teat contact. Each parameter was scored from 0 (bad) to 2 (good) according to predefined categories and summed up to an overall APGAR score. The influence of provision of oxytocin or manual intervention during farrowing, care of the new born by the farmer and obstetrics on viability was investigated. It was found, that new born care and the condition of the umbilical cord had the highest influence on piglet viability. Oxytocin and obstetrics had no influence on the viability of piglets and therefore on the APGAR score.

TRIENNIAL LACTATION SYMPOSIUM/BOLFA: Mammary growth during pregnancy and lactation and its relationship with milk yield.

The number of secretory cells in the mammary gland is often cited as a major determinant of milk production. However, literature data for proxy measures of secretory cell number do not fully support such a claim. In particular, measurements of total mammary DNA in livestock explain only <25% of variation in milk yield, probably because of tissue heterogeneity for DNA concentration. Relative to BW, measurements of udder size in dairy cattle, as total DNA or udder weight, are approximately double those seen in most other livestock classes. Therefore, selection for dairy production, not surprisingly, has resulted in cows with greater secretory capacity. There is limited evidence that genetic selection is still increasing udder size in some cattle populations, but more recent data are needed. It is contended that the most important period of mammary growth for determination of milk yield is that occurring in pregnancy and early lactation. Mammary development is largely complete, at term, in sheep, goats, and cattle, but in pigs, the udder continues to grow during the first 3 wk of lactation, depending, in part, on litter size. Increased litter size in sheep and goats will enhance the extent of mammary development at the end of gestation (and milk yield) by 20 to 25%. However, twinning in dairy cattle does not affect milk production and, by inference only, is not likely to affect numbers of secretory cells at term. Milking frequency and suckling intensity in very early lactation will increase milk yield in cows and increase mammogenesis and milk yield in sheep, indicating that even at term, the ruminant gland retains some capacity for further development, if demand requires it. There is limited understanding of the hormonal signals in pregnancy that regulate mammary development relative to the number of young carried. Furthermore, the genetic differences between dairy and beef cattle that lead to substantially greater udder size in the dairy breeds have not been identified. During lactation, the drivers for secretory cell loss in relation to milking frequency and nutritional status are still not known. Measurement of mammary development and using this phenotype in genomewide association studies to identify key genetic variants for mammogenesis will provide knowledge that is fundamental to understanding the quantitative regulation of milk production.

Selection for female traits of high fertility affects male reproductive performance and alters the testicular transcriptional profile

BackgroundMany genes important for reproductive performance are shared by both sexes. However, fecundity indices are primarily based on female parameters such as litter size. We examined a fertility mouse line (FL2), which has a considerably increased number of offspring and a total litter weight of 180% compared to a randomly bred control line (Ctrl) after more than 170 generations of breeding. In the present study, we investigated whether there might be a parallel evolution in males after more than 40 years of breeding in this outbred mouse model.ResultsMales of the fertility mouse line FL2 showed reduced sperm motility performance in a 5 h thermal stress experiment and reduced birth rate in the outbred mouse line. Transcriptional analysis of the FL2 testis showed the differential expression of genes associated with steroid metabolic processes (Cyp1b1, Cyp19a1, Hsd3b6, and Cyp21a1) and female fecundity (Gdf9), accompanied by 150% elevated serum progesterone levels in the FL2 males. Cluster analysis revealed the downregulation of genes of the kallikrein-related peptidases (KLK) cluster located on chromosome 7 in addition to alterations in gene expression with serine peptidase activity, e.g., angiotensinogen (Agt), of the renin-angiotensin system essential for ovulation. Although a majority of functional annotations map to female reproduction and ovulation, these genes are differentially expressed in FL2 testis.ConclusionsThese data indicate that selection for primary female traits of increased litter size not only affects sperm characteristics but also manifests as transcriptional alterations of the male side likely with direct long-term consequences for the reproductive performance of the mouse line.

Modelling piglet growth and mortality on commercial hog farms using variables describing individual animals, litters, sows and management factors

Increases in sow prolificacy have reduced piglet vitality, growth capacity and weight at weaning and even pig weight at slaughter. The aim of this study was to develop a model that predicts likelihood of mortality and weight at weaning. A database containing 3214 records of birth weight, weight gain at 24h, rectal temperature at 24h, litter size, age at weaning, fostering status, manual assistance of birth and oxytocin use as well as the corresponding 227 records of sow parity and feed intake was analysed using logit functions for mortality and linear functions for weaning weight. The best model of mortality predicted increased likelihood as birth weight, rectal temperature and 0–24h weight gain decreased and sow parity and time between births increased (P<0.01, χ2=2910). The best model of weaning weight predicted increases with increasing birth weight, 0–24h body weight gain, age at weaning and sow parity and decreases with increasing litter size at 24h (P<0.01; AICC=4324; RMSE=0.82). This study confirmed that birth weight and weight gain during the first 24h are the principal factors influencing piglet growth and pre-weaning mortality.

Effects of melatonin administration on embryo implantation and offspring growth in mice under different schedules of photoperiodic exposure

BackgroundEmbryo implantation is crucial for animal reproduction. Unsuccessful embryo implantation leads to pregnancy failure, especially in human-assisted conception. Environmental factors have a profound impact on embryo implantation. Because people are being exposed to more light at night, the influence of long-term light exposure on embryo implantation should be explored.MethodsThe effects of long photoperiodic exposure and melatonin on embryo implantation and offspring growth were examined. Long photoperiodic exposure (18:6 h light:dark) was selected to resemble light pollution. Melatonin (10−2, 10−3, 10−4, 10−5 M) was added to the drinking water of mice starting at Day 1 (vaginal plugs) until delivery.ResultsMelatonin treatment (10−4,10−5 M) significantly increased litter sizes compared to untreated controls (12.9 ± 0.40 and 12.2 ± 1.01 vs. 11.5 ± 0.43; P < 0.05). The most effective concentration of melatonin (10−4 M) was selected for further investigation. No remarkable differences were found between melatonin-treated mice and controls in terms of the pups’ birth weights, weaning survival rates, and weaning weights. Long photoperiodic exposure significantly reduced the number of implantation sites in treated mice compared to controls (light/dark, 12/12 h), and melatonin rescued this negative effect. Mechanistic studies revealed that melatonin enhanced the serum 17β-estradiol (E2) levels in the pregnant mice and upregulated the expression of the receptors MT1 and MT2 and p53 in uterine tissue. All of these factors may contribute to the beneficial effects of melatonin on embryo implantation in mice.ConclusionMelatonin treatment was associated with beneficial effects in pregnant mice, especially those subjected to long photoperiodic exposure. This was achieved by enhanced embryo implantation. At the molecular level, melatonin administration probably increases the E2 level during pregnancy and upregulates p53 expression by activating MT1/2 in the uterus. All of the changes may improve the microenvironment of the uterus and, thus, the outcomes of pregnancy.

DNA methylation patterns and gene expression associated with litter size in Berkshire pig placenta.

Increasing litter size is of great interest to the pig industry. DNA methylation is an important epigenetic modification that regulates gene expression, resulting in livestock phenotypes such as disease resistance, milk production, and reproduction. We classified Berkshire pigs into two groups according to litter size and estimated breeding value: smaller (SLG) and larger (LLG) litter size groups. Genome-wide DNA methylation and gene expression were analyzed using placenta genomic DNA and RNA to identify differentially methylated regions (DMRs) and differentially expressed genes (DEGs) associated with litter size. The methylation levels of CpG dinucleotides in different genomic regions were noticeably different between the groups, while global methylation pattern was similar, and excluding intergenic regions they were found the most frequently in gene body regions. Next, we analyzed RNA-Seq data to identify DEGs between the SLG and LLG groups. A total of 1591 DEGs were identified: 567 were downregulated and 1024 were upregulated in LLG compared to SLG. To identify genes that simultaneously exhibited changes in DNA methylation and mRNA expression, we integrated and analyzed the data from bisulfite-Seq and RNA-Seq. Nine DEGs positioned in DMRs were found. The expression of only three of these genes (PRKG2, CLCA4, and PCK1) was verified by RT-qPCR. Furthermore, we observed the same methylation patterns in blood samples as in the placental tissues by PCR-based methylation analysis. Together, these results provide useful data regarding potential epigenetic markers for selecting hyperprolific sows.

Glucosamine supplementation during late gestation alters placental development and increases litter size

BackgroundDuring late gestation the placental epithelial interface becomes highly folded, which involves changes in stromal hyaluronan. Hyaluronan is composed of glucoronate and N-acetyl-glucosamine. We hypothesized that supplementing gestating dams with glucosamine during this time would support placental folded-epithelial-bilayer development and increase litter size. In Exp. 1, gilts were unilaterally hysterectomized-ovariectomized (UHO). UHO gilts were mated and then supplemented daily with 10 g glucosamine (n = 16) or glucose (control, n = 17) from d 85 of gestation until slaughter (d 105). At slaughter, the number of live fetuses was recorded and each live fetus and its placenta was weighed. Uterine wall samples adjacent to the largest and smallest fetuses within each litter were processed for histology. In Exp. 2, pregnant sows in a commercial sow farm were supplemented with either 10 g glucosamine or glucose daily from d 85 of gestation to farrowing. Total piglets born and born alive were recorded for each litter. In Exp. 3, the same commercial farm and same protocol were used except that the dose of glucosamine and glucose was doubled to 20 g/d.ResultsIn Exp. 1, the number of live fetuses tended to be greater in glucosamine-treated UHO gilts (P = 0.098). Placental morphometry indicated that the width of the folded bilayer was greater (P = 0.05) in glucosamine-treated gilts. In Exp. 2, litter size did not differ between glucosamine- and glucose-treated sows. However in Exp. 3, the increased dose of glucosamine resulted in a significant treatment by parity interaction (P ≤ 0.01), in which total piglets born and born alive were greater in glucosamine treated sows of later parity (5 and 6).ConclusionsThese results indicated that glucosamine supplementation increased the width of the folds of the placental bilayer and increased litter size in later parity, intact pregnant commercial sows.