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

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

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

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