An Earlier Uterine Environment Favors the In Vivo Development of Fresh Pig Morulae and Blastocysts Transferred by a Nonsurgical Deep-uterine Method

This study aimed to evaluate the effect of recipient-donor estrous cycle synchrony on recipient reproductive performance after nonsurgical deep-uterine (NsDU) embryo transfer (ET). The transfers (N=132) were conducted in recipients sows that started estrus 24 h before (–24 h; N=9) or 0 h (synchronous; N=31), 24 h (+24 h; N=74) or 48 h (+48 h; N=18) after the donors. A total of 30 day 5 morulae or day 6 blastocysts (day 0=onset of estrus) were transferred per recipient. The highest farrowing rates (FRs) were achieved when estrus appeared in recipients 24 h later than that in the donors (81.1%), regardless of the embryonic stage used for the transfers. The FR notably decreased (P<0.05) when recipients were –24 h asynchronous (0%), synchronous (61.3%) or +48 h asynchronous (50%) relative to the donors. No differences in litter size (LS) and piglet birth weights were observed among the synchronous and +24 h or +48 h asynchronous groups. While a +24 h asynchronous recipient was suitable for transfers performed with either morulae (FR, 74.3%; LS, 9.2 ± 0.6 piglets) or blastocysts (FR, 84.6%; LS, 9.8 ± 0.6 piglets), a + 48 h asynchronous recipient was adequate for blastocysts (FR, 87.5%; LS, 10.4 ± 0.7 piglets) but not for morulae (FR, 30.0%; LS, 7.3 ± 2.3 piglets). In conclusion, this study confirms the effectiveness of the NsDU-ET technology and shows that porcine embryos tolerate better a less advanced uterine environment if they are nonsurgically transferred deep into the uterine horn.     

Two successful embryo transfers of mini-donkey embryos in Brazilian Northeastern jennies using an alternative method: Case report

Pregnancy rates after embryo transfer (ET) are disappointing in donkey species. This study aims to report two successful ET of mini-donkey embryos using Brazilian Northeastern jennies as recipients. Eighteen embryo flushes were performed 9 days post-ovulation in two non-pregnant mini-donkeys jennies (11 and 7 cycles per jenny). Eleven embryos (61%, 11/18) were collected and transferred to Brazilian Northeastern jennies 4–6 days post-ovulation by conventional (n = 6) or an alternative (n = 5) technique. The alternative method consisted of inserting a Polansky equine vaginal speculum smeared with lubricant in the vagina of the recipient jenny. The arms of the speculum were extended to allow the visualization of the cervix. Then, using an adapted crafted, elongated, toothed tissue grasping forceps, the external cervical os was held, and the cervix was gently pulled backward, aiming to straight the cervical canal. The ET gun was inserted through the vagina and cervix by visual inspection, and the embryo was released into the uterine lumen. All embryos collected were Grade 1 and classified as Expanded Blastocysts. No jennies become pregnant after conventional ET (0/6), whereas two recipient jennies (40%, 2/5) become pregnant and delivered offspring in the following year after ET using the alternative technique. In conclusion, Brazilian Northeastern jennies can be used as embryo recipients using the alternative method proposed in the present study. However, further investigations are needed to improve the knowledge and results of ET in donkey species.     

Insemination of recipient sows improves the survival to term of vitrified and warmed porcine expanded blastocysts transferred non‐surgically

This study was performed to evaluate reproductive performance after non‐surgical embryo transfer (Ns‐ET) of 10–15 porcine expanded blastocysts (ExBs) that had been vitrified and warmed (V/W) using the micro volume air cooling (MVAC) method. The effect of asynchrony between the donor and recipient estrous cycle was investigated. Ns‐ET was conducted in recipients whose estrous cycle was asynchronous to that of donors by a delay of 2, 1, or 0 days. In the 2‐day and 1‐day groups, the similar farrowing rates (27.3% and 25.0%) and survival rates to term (13.9% and 15.7%) were obtained after Ns‐ET of V/W ExBs. None of the recipients in 0‐day group farrowed. Artificial insemination (AI) prior to Ns‐ET was then evaluated. Ten–15 V/W ExBs were transferred non‐surgically to 12 recipients whose estrous cycles were asynchronous to that of donors by a 2‐day delay. All of the recipients produced piglets, and all (100.0%) delivered piglets were derived from the transferred V/W ExBs. The survival rate of V/W ExBs to term was 25.2%. These results demonstrate that Ns‐ET of V/W ExBs using MVAC can facilitate piglet production, even if 10–15 embryos are transferred. Moreover, piglets were obtained stably when AI was performed prior to Ns‐ET.     

受体绵羊人工授精后移植胚胎的试验

试验通过使用人工授精后绵羊作为受体进行胚胎移植,以寻找一种更加有效的方法提高绵羊胚胎移植的经济效益。试验中使用FSH对10只无角道赛特绵羊进行超数排卵处理,同时对60只受体小尾寒羊进行同期发情。供体羊在发情配种后4.5～5.0d从子宫角收集胚胎。同时,将胚胎移植到同期发情并进行人工授精的受体羊子宫内。总共有57枚可用胚移植给44只受体小尾寒羊,32只怀孕到分娩,共产下羔羊51只(无角道赛特羔28只,道赛特与小尾寒羊杂种羔23只)。此外,经人工授精但未进行手术移植的7只小尾寒羊产下15只杂种羔羊。移胚植受体妊娠率72.7%(32/44),移胚受体繁殖率118%(51/44),受体利用率88.3%(53/60)。移胚受体总妊娠率和受体利用率均显著高于常规ET组(P<0.01)。与常规胚胎移植相比,受体羊人工授精后移植胚胎不仅提高了无角道赛特母羊的繁殖率,而且提高了受体羊的利用率。     

Non‐surgical transfer of vitrified porcine embryos using a catheter designed for a proximal site of the uterus

This study aimed to compare the efficiency of non‐surgical embryo transfer (ET) using a newly developed catheter, which enables transferring embryos into a proximal site of the uterus (mostly uterine body), and surgical ET of vitrified porcine embryos. In Experiment 1, the catheter was inserted into 12 gilts, with each half of the group allocated to skilled or novice operators. The time required for insertion into the uterus did not differ between skilled and novice operators (4 min 9 s and 4 min 6 s, respectively). In Experiment 2, 12 gilts were used as recipients for non‐surgical and surgical ET with vitrified embryos (n = 6, each). There was no significant difference in the rate of piglet production based on the number of transferred embryos between surgical and non‐surgical ET (25.8% vs. 15.4%, p = .098). The results suggest that non‐surgical ET catheter allowed for easy insertion and transfer of embryos without special training. Although the catheter is effective for deposition of embryos into the proximal site of uterus, the efficiency of piglet production is not enhanced compared with surgical ET. The ET method using this catheter, being labor‐saving and less‐invasive, may contribute to the improvement of ET in pigs.     

Evaluation of cervical and uterine size,at 4 weeks postpartum,as a predictor of subsequent fertility in Jersey cattle

Uterine and cervical size of Holstein dairy cows is reported among reasons for a decline in dairy cow fertility. Therefore, the objectives of this study were to (a) determine whether size of the cervix and uterus at 4 weeks postpartum impacted subsequent fertility at first service in Jersey cattle, (b) determine whether progesterone level at 4 weeks postpartum impacted cyclicity and (c) the association of the presence of corpus luteum and uterus and cervix size. Body condition scores at calving, presence of postpartum diseases, parity number and milk weights were taken from lactating Jersey dairy cows (N = 147) for 28 days postpartum. During the fourth week postpartum, a blood sample was obtained for progesterone concentration, and transrectal ultrasonography was performed by a high-resolution ultrasound machine to determine cervical and uterine horn diameter, as well as ovarian structures measurements. Correcting for parity number, BCS at calving, presence of diseases and milk yield, cows with a cervix >2.54 ± 0.63 cm and uterine horn >2.25 ± 0.59 cm were less likely to become pregnant at first service (p = .04 and p = .003, respectively). The cows with larger cervix had a trend to be less likely to have a corpus luteum present at the 4th week of lactation (p = .067). Cows with larger uterine horn size were less likely to have a corpus luteum present at the 4th week of lactation (p = .015). It is concluded that a larger cervix and/or uterus during the postpartum was associated negatively with fertility and cyclicity in Jersey cows.     

Secondary Corpora Lutea Induced by hCG Treatment Enhanced Demi‐Embryo Survival in Lactating High‐Yielding Dairy Cows

Using a novel in vivo model considering a low developmental competence embryo (demi‐embryo) and a subnormal fertility recipient (lactating high‐yielding dairy cow), this experiment evaluated the effect of human chorionic gonadotrophin (hCG) treatment at embryo transfer (ET) on embryonic size at implantation, embryonic survival and recipient plasma progesterone (P₄) and bovine pregnancy‐specific protein B (PSPB) concentrations until day 63 of pregnancy. Embryos were bisected and each pair of demi‐embryos was bilaterally transferred to recipients (n = 61) on day 7 of the oestrous cycle. At ET recipients were randomly assigned to treatment with 1500 IU hCG or to untreated controls. Higher (p < 0.01) pregnancy rates on days 25, 42 and 63, and embryo survival rate on day 63 were observed in hCG‐treated cows with secondary CL than in hCG‐treated cows without secondary CL and in untreated cows. Pregnancy rates and embryo survival rate were similar in hCG‐treated cows without secondary CL and untreated cows. Embryonic size on day 42 was not affected by treatment with hCG, presence of secondary CL and type of pregnancy (single vs twin). Presence of secondary CL increased (p < 0.05) plasma P₄ concentrations of pregnant cows on days 14, 19 and 25 but not thereafter and of non‐pregnant cows on days 14–21. Treatment with hCG and presence of secondary CL had no effect on plasma PSPB concentrations, which were higher (p < 0.05) in twin than in single pregnancies. In conclusion, secondary CL induced by hCG treatment at ET significantly increased plasma P₄ concentrations, the survival rate of demi‐embryos and the pregnancy rate of high‐yielding lactating dairy cows. Embryos were rescued beyond maternal recognition of pregnancy, but later embryonic survival, growth until implantation and placental PSPB secretion until day 63 of pregnancy were not affected by treatment or presence of secondary CL.     

The effect of artificial insemination prior to transfer of a limited number of vitrified and warmed porcine embryos by open pulled straw (OPS) method on their survival ability for farrowing

Embryo transfer (ET) of 20 porcine expanded blastocysts (ExBs) vitrified and warmed (VW) by open pulled straw (OPS) to a recipient allows stable piglet production. The efficiency of artificial insemination (AI) prior to ET of 10 VW ExBs for piglet production was investigated. For one trial, 10–15 VW ExBs from single donor were assigned, 10 were used for ET and the remains were assessed for their in vitro viability. In the non‐AI/ET group, 10 were transferred to each of five recipients. As AI/ET group, 10 were transferred to each of five recipients after AI. In AI/non‐ET group, only AI was performed to seven gilts. In the non‐AI/ET group, the pregnancy rate was 40%, but none of them farrowed. In the AI/ET group, all recipients produced piglets. Four (80.0%) delivered piglets from transferred VW ExBs. The survival rate of VW ExBs to term was 20.0% (10/50). In the AI/non‐ET group, six of the seven gilts farrowed. There was no difference in in vitro viability between the non‐AI/ET and AI/ ET groups (62.5% and 68.3%, respectively). AI prior to ET can be an appropriate way to maintain pregnancy and assist the development of a low number of VW ExBs to term.     

The effects of an advanced uterine environment on embryonic survival in the mare

Reasons for performing the study: During embryo transfer (ET) the equine embryo can tolerate a wide degree of negative asynchrony but positive asynchrony of >2 days usually results in embryonic death. There is still confusion over whether this is due to the inability of the embryo to induce luteostasis or to an inappropriate uterine environment. Objectives: To assess embryo survival and development in an advanced uterine environment. Hypothesis: Embryo–uterine asynchrony, not the embryo's inability to induce luteostasis, is responsible for embryonic death in recipient mares with a >2 days chronologically advanced uterus. Methods: Experiment 1: Thirteen Day 7 embryos were transferred to the uteri of recipient mares with luteal prolongation, occasioned by manual crushing of their own conceptus, such that donor–recipient asynchrony was between +13 and +49 days. Experiment 2: Day 7 embryos were transferred to recipient mares carrying their own conceptus at Days 18 (n = 2), 15 (n = 2), 14 (n = 4), 12 (n = 4) or 11 (n = 4) of gestation. In addition, Day 8 embryos were transferred to 4 pregnant recipient mares on Day 11 of gestation. Results: No pregnancies resulted following transfer of Day 7 embryos to recipients in prolonged dioestrus with asynchronies between +13 and +49 days. However, the use of early pregnant mares as recipients resulted in 5/20 (25%) twin pregnancies, 4 of which came from the transfer of a Day 8 embryo to a Day 11 recipient. All transferred embryos showed retarded growth, with death occurring in 4/5 (80%). Conclusions and potential relevance: The results emphasise the importance of an appropriate uterine environment for embryo growth and the inability of equine embryos to survive transfer to a uterus >2 days advanced even when luteostasis is achieved. It is possible that in normal, non‐ET equine pregnancy, embryo–uterine asynchrony may account for some cases of embryonic death.     

Tumors and tumor-like lesions in the genitalia of sows

Of a total of 1445 sows, tumors were detected in the uterus of 11 animals and in the cervix/vagina of 1 animal. Tumor-like lesions were detected in the ovary of 56 animals. The incidence of tumors was higher than that mentioned in the literature, possibly because of the relatively high age of the sows (mean parity of 6.8) and the accuracy of investigation. Several tumors would not have been detected during routine slaughter examination. The uterine tumors were diagnosed as leiomyoma (6), fibroma (3), cyst-adenoma (1) and fibro-leiomyoma (1). The cervical/vaginal tumor appeared to be a fibroma. The ovarian lesions could not be satisfactorily classified. They consisted of connective tissue, blood vessels, and granulosa cells, which were present in variable quantities in different ovaries and in different sides of the same ovary. Sows with tumors were older than the mean determined age at slaughter (parity 6.8). Sows with uterine and cervical/vaginal tumors had a parity of 11.6; sows with ovarian lesions had a parity of 9.0. Sows with uterine- or a cervical/vaginal tumor were often slaughtered for infertility reasons.     

Evaluation of high nutrient diets and additional dextrose on reproductive performance and litter performance of heat‐stressed lactating sows

This study investigated the litter performance of lactating sows fed nutrient‐dense diets with or without dextrose at farrowing to weaning, during the summer with an average room temperature of 28.4°C. A total of 60 (13 first parity, 13 second parity, 19 third parity, and 15 forth parity) cross‐bred sows were assigned to three treatments. The three treatments were: standard diet (ST), high nutrient diet (HN; ST + 3% higher energy and 18.0% protein), and high nutrient diet plus dextrose (HND; 3% higher energy, 18.0% protein, and 5% dextrose). BW loss was reduced in the HND sows compared with the ST sows during lactation. The HN and HND sows had a higher piglet and litter weight at weaning. Also, the HND sows had the highest post‐prandial insulin levels at weaning and the shortest weaning‐to‐service interval (WSI). Serum LH was higher in the HND sows than the ST sows. The milk fat level was higher in the HND sows compared with the ST sows, but similar to the HN sows. In conclusion, these results suggest that it is possible to increase the blood insulin response by supplementing dextrose to a high nutrient diet, thus, improving WSI interval and litter growth during heat stress.     

Evaluation of the factors that affect the pregnancy rates during embryo transfer in beef heifers

The aim of this study was to evaluate the effects of the transfer side, transfer location, cervix transfer score, type and diameter of corpus luteum (CL) during embryo transfer on pregnancy rates in beef heifers. Progesterone-based synchronization and superovulation protocol were applied to Simmental cows used as donors (n = 168). Uterine flushings were performed on day 7 following artificial insemination. Obtained Code I (excellent or good) and II (fair) quality embryos were transferred to recipient beef heifers (n = 561). During embryo transfer, side of transfer (right or left), transfer location (the cranial or middle third of uterine horn), cervix transfer score (easy, moderate or difficult) and type (CLa, CLb and CLc) and diameter of CL were determined. Pregnancy rates following the transfer of Code I and II embryos were 44.66% and 33.07%, respectively (p < .05). The rates of pregnancy after transfers to the right and left uterine horn were 37% and 42.2%, respectively (p > .05). The pregnancy rates were 41.2%, 34.9% and 30.3% for cervix transfer scores as easy, moderate and difficult, respectively (p > .05). Pregnancy rates after transfer to the cranial third and middle third were 41.06% and 29.67%, respectively (p < .05). According to types of CL, pregnancy rates were 31.7%, 40.4% and 45.3% for CLa, CLb and CLc, respectively (p < .05). Moreover, it was found that as the CL diameter increased, the pregnancy rates increased. As a result, it was concluded that there was no effect of side of transfer and cervix transfer score, but embryo quality, transfer location, type and diameter of CL had significant effects on the pregnancy rate during embryo transfer in beef heifers.     

Effects of Pre‐Weaning Energy Substitutions on Post‐Weaning Follicle Development,Steroid Hormones and Subsequent Litter Size in Primiparous Sows

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

Hormonal therapy for sows weaned during fall and winter

Sows from five commercial herds were weaned in the fall and winter and used to ascertain the potential application of hormonal therapy to stimulate subsequent litter size born. At weaning sows within parity (1, 2, and 3 through 6) and lactation length classification (early weaned, < or = 14 d; conventionally weaned, > 14 d) were randomly assigned to treatment. Treatments were injection with P.G. 600 (400 IU PMSG with 200 IU hCG) at weaning or no treatment. Sows were individually observed for estrus and mated following protocol for each herd. Breeding, culling, and farrowing data were collected. Treatment with P.G. 600 did not change subsequent rebreeding performance for sows at parity 1 or parities 3 through 6. However, conventionally weaned parity-2 sows treated with P.G. 600 were more likely (P < .05) to return to estrus than conventionally weaned controls (99.0 vs 93.6%, respectively). For parity-1 and parity-2 sows, treatment did not significantly change the likelihood for farrow percentage. However, the likelihood to farrow a litter was greater (P < .05) among P.G. 600-treated sows at parities 3 to 6 that were conventionally weaned (84.4 vs 71.3%, respectively). Subsequent litter birth weight for parity-1 sows treated with P.G. 600 was lower (P < .02) than for controls (15.6 vs 16.6 kg, respectively). Subsequent litter size at birth was not affected by treatment for parity-1 or parity-2 sows compared with controls. However, early-weaned sows at parities 3 through 6 treated with P.G. 600 had more (P < .06) total number born than controls (12.4 vs 10.6, respectively). Treatment with P.G. 600 improved reproductive function within specific parity and lactation length classification for sows weaned in the fall and winter.     

Evidence that oxidative stress is higher in replacement gilts than in multiparous sows

The recent success obtained in term of increasing the litter size of sows has not correlated with a reduction of replacement rate. There is thus an increased economic demand for gilts with optimal reproductive potential and longevity. Unfortunately, replacement gilts are known to be more susceptible to diseases and less productive than multiparous sows. Interestingly, reproductive performance, resistance to diseases and longevity could all be largely affected by oxidative stress. To investigate whether oxidative stress conditions could account for the poor longevity of gilts, three distinct groups of conventional Yorkshire × Landrace sows were formed based on their similar age and parity (gilts, second parity sows as well as fourth to fifth parity sows). All animals were slaughtered during the post‐ovulatory period, and blood as well as tissue samples were collected. Biomarkers of oxidative damage to proteins (carbonyls) and DNA (8‐OHdG) were analysed in samples. Specific mRNA expression of major antioxidants such as glutathione peroxidases 1, 3 and 4 (GPx1, GPx3, GPx4) as well as superoxide dismutases 1 and 2 (Sod1, Sod2) were monitored in liver and kidney samples by quantitative RT‐PCR. Specific enzymatic activities of both GPx and SOD were measured by spectrophotometric assays. The plasma concentration of protein carbonyls was significantly different between the three groups with the highest concentration being observed in gilts (p ≤ 0.001). The mRNA expression levels of GPx1 and GPx4 were also significantly increased in the liver of gilts when compared to multiparous sows (p ≤ 0.05). SOD2 enzymatic activity was found to be higher in the liver of gilts than multiparous sows (p ≤ 0.05). Taken together, these results indicate that replacement gilts sustain significantly higher oxidative conditions than multiparous sows. Current findings may contribute to the design of nutritional regimens that will increase the productivity of gilts by counteracting oxidative stress.     

Effects of the standardized ileal digestible valine : lysine ratio on performance,milk composition and plasma indices of lactating sows

To determine the effects of standardized ileal digestible (SID) valine : lysine ratio on the performance, milk composition and plasma indices of lactating sows, 32 Large White × Landrace sows (219.78 ± 7.15 kg body weight; parity 1.82 ± 0.62) were allotted to one of four dietary treatments with eight sows per treatment based on parity, back fat thickness and body weight. The sows were fed corn‐soybean meal‐based diets containing 63, 83, 103 or 123% SID valine : lysine from day 107 of gestation until day 28 of lactation. The average daily feed intake of sows and daily weight gain of piglets increased linearly (P < 0.05) while back fat loss decreased linearly (P < 0.05) as the SID valine : lysine ratio increased. All of the analyzed amino acids in sow colostrum and valine concentrations of sow and piglet plasma increased linearly (P < 0.05) with the increasing SID valine : lysine ratio. In conclusion, 88 and 113% dietary SID valine : lysine ratios were optimal to achieve minimum back fat loss and maximum piglet growth rate using a linear‐break point model which exceeds the requirement of 85% that is estimated by the National Research Council (2012).     

Oxytocin receptors in dioestrous and anoestrous canine uteri

The aim of the study was to localize oxytocin receptors (OTR) and measure mRNA expression of OTR in the canine uterus with and without the influence of progesterone. Uterine samples were taken from nine anoestrous and eight dioestrous bitches during ovariohysterectomy. Histological changes were evaluated in haematoxylin and eosin (HE)‐stained samples. Purified polyclonal antibody for OTR was used in immunohistochemistry to localize receptors in uterine layers. Relative mRNA concentration of OTR was evaluated with real‐time PCR from full‐thickness uterine samples taken from the middle horn and the body. Myometrial smooth muscle cells, endometrial luminal epithelium (LE) and deep and superficial glandular epithelium were positively stained for oxytocin receptors in non‐pregnant animals. No significant difference in staining intensity was detected between uterine middle horn and body. However, the staining intensity of LE was significantly higher in dioestrous than in anoestrous uteri (p < .05). Leucocytes and endothelium of blood vessels were also positively stained for OTR. Real‐time PCR showed no significant differences in OTR mRNA expression between the middle horn and the body of the uterus, or between anoestrous and dioestrous uterus. No correlation was noted between OTR mRNA expression and blood progesterone concentration. In conclusion, despite the apparent inactivity, the uterus of the non‐pregnant bitch expresses OTR. The distribution or relative expression of OTR does not differ between uterine horn and body in dioestrus or anoestrus except in LE. LE may have more oxytocin‐dependent activity during dioestrus than anoestrus.     

Effects of Dietary Supplementation of β‐hydroxy‐β‐methylbutyrate on Sow Performance and mRNA Expression of Myogenic Markers in Skeletal Muscle of Neonatal Piglets

The effects of dietary β‐hydroxy‐β‐methylbutyrate (HMB) supplementation during gestation on reproductive performance of sows and the mRNA expression of myogenic markers in skeletal muscle of neonatal pigs were determined. At day 35 of gestation, a total of 20 sows (Landrace × Yorkshire, at third parity) were randomly assigned to two groups, with each group receiving either a basal diet or the same diet supplemented with 4 g/day β‐hydroxy‐β‐methylbutyrate calcium (HMB‐Ca) until parturition. At parturition, the total and live litter size were not markedly different between treatments, however, the sows fed HMB diet had a decreased rate of stillborn piglets compared with the sows fed the control (CON) diets (p < 0.05). In addition, piglets from the sows fed HMB diet tended to have an increased birth weight (p = 0.08), and a reduced rate of low birth weight piglets (p = 0.05) compared with piglets from the CON sows. Nevertheless, lower feed intake during lactation was observed in the sows fed the HMB diet compared with those on the CON diet (p < 0.01). The relative weights of the longissimus dorsi (LD) and semitendinosus (ST) muscle were higher (p < 0.05) in neonatal pigs from the HMB than the CON sows. Furthermore, maternal HMB treatment increased the mRNA levels of the myogenic genes, including muscle regulatory factor‐4 (MRF4, p < 0.05), myogenic differentiation factor (MyoD) and insulin‐like growth factor‐1 (IGF‐1, p < 0.01). In conclusion, dietary HMB supplementation to sows at 4 g/day from day 35 of gestation to term significantly improves pregnancy outcomes and increases the expression of myogenic genes in skeletal muscle of neonatal piglets, but reduces feed intake of sows during lactation.     

Achievements and future perspectives of embryo transfer technology in pigs

Commercial embryo transfer (ET) has unprecedented productive and economic implications for the pig sector. However, pig ET has been considered utopian for decades mainly because of the requirements of surgical techniques for embryo collection and embryo deposition into recipients, alongside challenges to preserve embryos. This situation has drastically changed in the last decade since the current technology allows non‐surgical ET and short‐ and long‐term embryo preservation. Here, we provide a brief review of the improvements in porcine ET achieved by our laboratory in the past 20 years. This review includes several aspects of non‐surgical ET technology and different issues affecting ET programmes and embryo preservation systems. The future perspectives of ET technology are also considered. We will refer only to embryos produced in vivo since they are the only type of embryos with possible short‐term use in pig production.     

Biochemical and Protein Profile of Alpaca (Vicugna pacos) Uterine Horn Fluid During Early Pregnancy

South American camelids show high embryo loss rate, during the first 60 days of pregnancy. One of the factors which may be related to this situation is that over 98% of the embryos implant in the left uterine horn (LUH) even though both ovaries contribute similarly to ovulation. There is scarce information about the uterine environment of female camelids at any physiological state that could explain the capability of the LUH to attract the embryo and maintain pregnancy. We describe, for the first time, the biochemical and protein profile of uterine fluid (UF), addressing the right and LUH environment in non‐pregnant and pregnant alpacas. Different substrates, electrolytes and metabolites were assayed in both uterine horn fluids. Small changes were observed in glucose and total protein levels, which were more noticeable during pregnancy. In addition, 10 specific proteins were found in the left horn fluid in 5‐week‐pregnant alpacas, and two protein bands were identified in non‐pregnant alpaca right horn fluid. These results would provide basic information for identification of possible markers for pregnancy diagnosis, reproductive diseases and hormone‐treated animals evaluation and hence contributing to improve the pregnancy rate.