Effects of ambient temperature and transportation distances on the resulting pork quality

Factors beyond the farm gate can affect the quality pork product, among them temperature and amount of time for transport. This study examines how these factors affect producers selling in the niche pork market

The impacts of uterine type and fetal genotype on determining litter size in the pig

Prolific Chinese Meishan pigs have an ovulation rate (16-18 ova), fertilization rate and uterine size similar to females of U.S. pig breeds yet farrow three to four more piglets per litter. To determine the mechanism(s) for this increased litter size two studies focused on breed comparisons of the interaction between uterine type and fetal genotype during late gestation. A third study examined the effects of utilizing a selection criterion based on information obtained in the first two studies to increase litter size, piglet survivability, 21-d weights and days to 105 kilograms;Experiment 1. The surface area of Yorkshire placentae doubled in size (P \u3c.001) between days 90 and 110 of gestation while placental and adjacent endometrial vascular density remained relatively constant. In contrast, there was no increase in placental surface area between day 70 and day 110 in the Meishan pig. Instead, the vascular density of Meishan placentae and adjacent endometrium increased markedly (P \u3c.05). As a consequence the ratio of fetal weight/placental weight (placental efficiency; RATIO) was greater for Meishan compared to Yorkshire conceptuses;Experiment 2. Meishan x Yorkshire crossbred conceptuses were 40% smaller when recovered from Meishan or Yorkshire uteri on either day 90 or day 110 of gestation. While fetal weight increased (P \u3c.001) between day 90 and day 110, regardless of uterine environment, placental size remained unchanged. Additionally, the vascular density of placentae and the associated endometrium were similar, regardless of uterine type and remained constant from day 90 to day 110 of gestation. RATIO was similar for conceptuses in either uterine type. While placental weight was significantly correlated with RATIO (r = -.66, P \u3c.001), fetal weight was not;Experiment 3. No significant association was seen between RATIO and piglet weight at 21-days, days to 105 kilograms, back fat depth or loin muscle area in a herd of purebred Yorkshire and Landrace breeding stock. Thus an above average RATIO is indicative of a smaller more efficient placenta which appears to have no detrimental effects on growth rate;Combined, these experiments indicate that selecting for females with the capacity to limit placental growth should maintain an optimum litter size. Additionally, selecting piglets with a high placental efficiency would not inhibit economically important production traits

Selection of Piglets with a Reduced Placental Size Does Not Hinder Production Traits

Using a purebred population of Yorkshire (Y) females, our laboratory recently reported that the ratio of a piglet\u27s weight to that of its placenta (RATIO) varies ≈threefold within a litter. This variation in RATIO is due predominantly to variations in placental weight that are known to be a limiting factor in litter size. It was further determined that selection of boars and gilts with a higher than average RATIO for breeding resulted in an increased litter size and reduced placental weights. The objective of this experiment was to examine the effects of RATIO on economically important production traits (21- day weight, days to 105 kg and backfat and loin area at 105 kg) in a purebred breeding stock herd of Y and Landrace pigs. Sows were monitored throughout farrowing, and as each piglet appeared its umbilical cord was clamped close to the dam\u27s vulva and again near the neonates body then cut between the clamps. A number designating birth order was then tied around the exposed umbilical cord with surgical silk and the tagged umbilical cord was allowed to retract back into the birth canal. Each piglet was then notched to match its numbered placenta. Following expulsion, placentae were separated, piglets and placentae weighed, and RATIO determined for each. Piglets were individually weighed at 21 days and scanned by ultrasound at 105 kg for backfat thickness and loin area. Placental weight exhibited a significant (P\u3c.0001) negative correlation with RATIO (r=- .73), whereas birth weight did not (r=.09, P\u3e.25). Further, neither 21-day weight nor days to 105 kg were associated with RATIO. Additionally, carcass quality was not associated with RATIO. These data indicate that piglet selection based on a high RATIO (increased placental efficiency) is not detrimental to economically important production traits. Data will continue to be compiled on the tagged gilts as they reach breeding age to determine if their selection for increased placental efficiency results in increased litter size

The Effect of Uterine Environment on Meishan and Yorkshire Fetal Development and Placental Size and Vascularity

When Meishan (M) and Yorkshire (Y) embryos were cotransferred to Y recipients that were then allowed to farrow, it was observed that the birth weights of M and Y littermates were similar averaging 1.15 ± .06 kg. In contrast, placentae matched to M piglets were markedly smaller (.70% lighter) and more vascular (.two-fold) than Y placentae. To investigate the effect of uterine environment on conceptus development to term, M and Y embryos were cotransferred to M recipients (n=3) that were slaughtered one day before expected parturition (day 113). Fetal weight, placental weight, and placental surface area were recorded. Additionally, a section of the intact maternal placental interface was excised, fixed, embedded, sectioned, and stained to allow quantitation of the placental vascular density (PVD). As observed when M and Y fetuses were cogestated by Y recipients, littermate M and Y fetuses gestated in M uteri were similar in weight (1.04 ± .03 vs. 1.03 ± .05 kg) at term. Further, M conceptuses exhibited markedly reduced (P\u3c.03) placental weights (170 ± 19 vs. 249 ± 10 g) and surface areas (1017 ± 70 vs. 1506 ± 96 cm 2 ) compared with their Y littermates. As was the case for conceptuses gestated in Y uteri, the similarity in fetal weight between the two breeds with very different placental sizes appears to result from an increased (P\u3c.09) M PVD compared with littermate Y fetuses (2.5 ± .3 vs. 1.4 ± .4%). These data indicate that in both the M and Y uterine environment, the reduced size of the M compared with Y placenta is compensated for by an increase in PVD. Currently it is unknown whether M placentae contain a greater amount of vasculature (total volume) or a similar amount of vasculature simply squeezed into a smaller space. To investigate breed differences in total placental vasculature we have perfused placentae of M and Y conceptuses cogestated in M uteri on d 113 of gestation with vascular casting material and will compare the volumes of the corrosion casts

A Decreased Placental Size and Increased Vascular Density Results in Increased Prolificacy in the Meishan Pig

The Chinese Meishan pig farrows 3 to 5 more pigs per litter than U.S. pig breeds. When Meishan and Yorkshire embryos are co-transferred to a Yorkshire recipient, Meishan fetuses and placentae are smaller than Yorkshire fetuses and placentae through day 90 of gestation. At farrowing, Meishan placentae are still smaller than Yorkshire placentae; however, Meishan fetuses are born at the same weight as their Yorkshire littermates. This tremendous growth of the Meishan fetus between day 90 and term is the result of an increased vascularization of the Meishan placenta. In this experiment we investigated the time course of placental vascular development of Meishan and Yorkshire conceptuses during late gestation. Our results demonstrate that Yorkshire fetuses increase the potential for nutrient extraction from the maternal blood by increasing the size of their placentae; however, Meishan fetuses achieve the same end by increasing the density of placental blood vessels while maintaining a constant placental size. The increased vascular density of the Meishan placenta then allows the conceptus to occupy less space in the uterus, allowing more fetuses to survive to term

Differential Prepartum and Postpartum Growth Patterns of Yorkshire and Meishan Piglets Gestated in the Same Uterine Environment

While Yorkshire fetal growth appears to depend on increasing placental size, more extensive vascularization of a smaller placenta appears to support Meishan fetal growth. Further studies are needed to extend our knowledge of the mechanisms controlling placental growth and vascularization. The ability to manipulate conceptus size may allow producers the opportunity to increase litter size in domestic pigs. More piglets farrowed per sow per year combined with the effects of fetal genotype on postpartum growth rate, as confirmed by the current study, would allow more efficient pork production

Selection for Litter Size by Using the Ratio of Piglet Weight: Placental Weight as a Measure of Placental Efficiency

The Chinese have been selectively breeding pigs for 7,000 to 10,000 years for increased numbers of pigs born, regardless of birth weight, indirectly resulting in the optimization of placental size and vascularity. In the United States, pig producers have generally selected for larger piglets at birth, resulting in a marked variation in placental size and vascularity. This tremendous variation in placental size and vascularity present within a litter may be ultimately limiting litter size. Therefore, by selecting against the large relatively avascular placentae, the potential for dramatically increasing litter size exists

Role of Embryonic and Maternal Genotype on Prenatal Survival and Foetal Growth in Rabbit

[EN] The aim of this work was to evaluate the influence of maternal and embryonic genotype on prenatal survival and foetal growth during pregnancy. Embryos were recovered at 48 h of gestation from two different donor lines (R = 46 and A = 40) and transferred to nulliparous recipient does (26 R and 24 A). Each recipient doe received six embryos into one oviduct from line R, and six embryos form line A into the other. Laparoscopy was performed at Day 14 to determine implantation rate. Recipient females were slaughter at Days 14, 24 and 30 (12, 24, and 14, respectively) to determine the number of live foetuses and the weight of live foetuses, foetal placenta and maternal placenta. A transcriptome analysis was performed to search for differences between foetal placentas at Days 14 and 24 of development. Prenatal survival at Days 14, and 24 was affected by embryonic genotype and determined by maternal genotype at Day 30. Foetal weight at Day 14 was influenced by both genotypes, being the weight higher for group A/A (0.29 0.01 g vs 0.19 0.01 g, for group R/R). However, both genotypes were determinant for foetal placenta weight at Day 24, while those genotypes affected maternal placenta weight at Day 30. Nevertheless, no differences in foetal placenta at transcriptome level and progesterone and IGF-I plasma levels in recipient does were found. In conclusion, results indicate that the influence of embryo and maternal genotype on the prenatal survival and growth seems to be changing over gestation.Naturil Alfonso, C.; Marco Jiménez, F.; Jiménez Trigos, ME.; Saenz De Juano Ribes, MDLD.; Viudes De Castro, MP.; Lavara García, R.; Vicente Antón, JS. (2015). Role of Embryonic and Maternal Genotype on Prenatal Survival and Foetal Growth in Rabbit. Reproduction in Domestic Animals. (50):312-320. doi:10.1111/rda.12493S3123205