Factors affecting the reproductive performance of the weaned sow.

The majority of sows return to estrus within 2 weeks after weaning. Swine practitioners attempt to optimize production by reducing the WEI. Some sows fail to resume estrous cyclicity after weaning; however, the endocrinologic pathogenesis of these anestrous sows is speculative. The average WEI is influenced by numerous factors, including season, environmental temperature, photoperiod, nutrition, stress, facility design, lactation length, and management practices. It is evident that the majority of these factors have a more profound influence on primiparous sows than on multiparous sows. Optimum protein and energy consumption by sows during lactation and after weaning and effective utilization of breeding facilities reduce the WEI. The precise roles of photoperiodic changes, elevated environmental temperatures, and stress in seasonal infertility remain poorly understood. Fortunately, current management techniques have reduced the WEI on most farms without instituting therapeutic measures.     

Effects of immune challenge on concentrations of serum insulin-like growth factor-I and growth performance in pigs

This study was designed to determine the long-term effects of repeated endotoxin treatment or immunization against human serum albumin on concentrations of serum insulin-like growth factor-I (IGF-I) and other indicators of growth performance in growing pigs. Thirty gilts (38.5 +/- 0.9 kg) were randomly assigned to 5 treatment groups (n = 6 animals/group): 1) lipopolysaccharide injections, 2) lipopolysaccharide pair-fed, 3) human serum albumin immunization, 4) human serum albumin pair-fed, and 5) control. Pigs in the lipopolysaccharide group were treated intramuscularly with lipopolysaccharide on Days 0-3. The pigs in the human serum albumin group were immunized with human serum albumin emulsified in Freund's adjuvant on Day 0 and administered a booster on Day 28. The lipopolysaccharide pair-fed pigs were matched by body weight and pair-wise fed with pigs treated with lipopolysaccharide. Similarly, human serum albumin pair-fed pigs were matched to human serum albumin immunized pigs. Serum IGF-I concentrations did not differ between or within groups. There was no difference in feed disappearance between groups prior to the initiation of treatments. The lipopolysaccharide group had a decrease (P = 0.013) in feed disappearance on Day 0 compared with control and human serum albumin groups. On Day 1, both lipopolysaccharide and human serum albumin groups differed (P < 0.05) from control. Average daily gain and total weight gain did not differ between groups; however, feed efficiency differed (P < 0.05) between lipopolysaccharide and control groups. Long-term effects of repeated endotoxin challenge or immunization on IGF-I concentrations and growth were not evident in the present study. This failure presumably was due to the development of endotoxin tolerance and a relatively innocuous vaccination against human serum albumin.     

Endocrine changes associated with cystic ovarian degeneration in sows.

Endocrine changes in sows with ovarian cysts were determined to be comparable with those in sows in diestrus. Blood samples were collected at frequent intervals from 5 sows affected with cystic ovaries. Concentrations of serum luteinizing hormone, progesterone, estradiol-17 beta, and cortisol were determined by use of established radioimmunoassays. The development of ovarian cysts has been proposed to be associated with a deficiency of luteinizing hormone rather than an intrinsic ovarian abnormality. In contrast, the results of this study demonstrated that tonic and pulsatile luteinizing hormone release were not affected adversely in sows with cystic ovaries.     

Effects of stress associated with weaning on the adaptive immune system in pigs

This study was designed to investigate the effects of weaning age on specific components of the adaptive immune system in pigs. Twenty-three crossbred pigs were randomly assigned to 1 of 3 treatments: weaning at 14 (14D, n = 8), 21 (21D, n = 7), or 28 (28D, n = 8) d of age. Peripheral blood samples, obtained when pigs were 13, 15, 20, 22, 27, 29, and 35 d of age, were analyzed for peripheral blood cell percentages and concentrations of neutrophils, lymphocytes, T cell subsets, mature B cells, and plasma cortisol concentrations. For each of the 3 groups, weaning increased plasma cortisol concentrations (P < 0.001) and reduced BW percentage change (P < 0.017). Lymphocyte concentrations displayed a treatment effect for the 14D (P = 0.074) and 28D (P = 0.014) groups. Albeit inconsistent, lymphocyte concentrations were less in weaned pigs on the day after weaning than in pigs remaining on the sow or weaned at a younger age. Specifically, mature B cells (CD21(+)) and CD4(+)CD8(+) cells decreased (P < 0.05) after weaning at 28 d of age. Other differences occurred among treatments; however, the differences apparently were not associated with weaning. Based upon the immunological measures used in the present study, there was not an explicit benefit to the adaptive immune system for any weaning age. Early weaning did not negatively affect the adaptive immunological competence of pigs as determined by changes in populations of immune cells.     

Lactose Synthase Components in Milk: Concentrations of α-Lactalbumin and β1,4-Galactosyltransferase in Milk of Cows from Several Breeds at Various Stages of Lactation

It is believed that milk production is determined by the number and activity of mammary secretory cells. Secretory activity, as assessed by milk volume, depends on secretion of the major osmole in milk, lactose, which is produced by lactose synthase. The amount of either of the two proteins in lactose synthase may regulate milk production. The objective of this study was to determine whether the concentrations in milk of the two components of lactose synthase, α‐lactalbumin (α‐LA) and β1,4‐galactosyltransferase (B4GALT), were related to genetic background, stage of lactation, breed or parity of dairy cows. α‐Lactalbumin and B4GALT concentrations were measured by ELISA and by enzyme assays, respectively, from single milk samples. Two herds with a total of 279 cows were used in the analysis. One herd contained Ayrshire, Brown Swiss, Holstein and Jersey cows; the second herd contained two groups of cows; Holsteins selected for high milk production and Holsteins with 1960s genetics. The α‐LA concentration in milk was greater in Jerseys and Ayrshires than in Holsteins and Brown Swiss. However, no difference in α‐LA concentration was observed in milk from high and low genetic merit cows in the Minnesota herd or among different genetic backgrounds in the Illinois herd. β1,4‐Galactosyltransferase concentrations were similar for all groups that were analyzed. α‐Lactalbumin concentrations were positively correlated with milk protein concentration, milk fat concentration and lactose concentration. β1,4‐Galactosyltransferase concentration in milk exhibited a strong positive correlation with number of days in milk. Although the concentration of B4GALT increased as lactation progressed, the values did not show any correlation with persistency of lactation or late lactation milk production. In conclusion, this survey shows that the two components of lactose synthase are each correlated to protein concentration and individually correlated to the concentration of other milk components and stage of lactation.     

Organogenesis and foetal haemodynamics during the normal gestation of healthy black‐rumped agoutis (Dasyprocta prymnolopha,Wagler, 1831) bred in captivity

The objective of this study was to define the patterns of organogenesis and foetal haemodynamics during the normal gestation of healthy agoutis (Dasyprocta prymnolopha) kept in captivity. Thirty pregnant agoutis that ranged in size from small to medium and weighed between 2.5 and 3 kg underwent B‐mode and Doppler ultrasonography for the biometric evaluation of the foetal organs. The foetal aortic blood flow proved to be predominantly systolic, and the measured flow velocity was 78.89 ± 2.95 cm/s, with a maximum pressure gradient of 2.12 ± 0.27 mmHg. The liver was characterized by its large volume, occupying the entire cranial aspect of the abdominal cavity, and it was associated cranially with the diaphragm and caudally with the stomach. The flow velocity in the portal vein was estimated to equal 12.17 ± 2.37 cm/s, with a resistivity index of 0.82 ± 0.05. The gallbladder was centrally located and protruded cranially towards the diaphragm. The spleen was visualized as an elongated structure with tapered cranial and caudal extremities, and the foetal kidneys were visualized bilaterally in the retroperitoneal region, with the right kidney positioned slightly more cranially than the left. The morphological characterization and hemodynamic analysis of the foetal organs of black‐rumped agoutis via B‐mode and Doppler ultrasonography allow determination of the vascular network and of reference values for the blood flow required for perfusing the anatomical elements essential for maintaining the viability of foetuses at different gestational ages.     

Exogenous DNA Uptake of Boar Spermatozoa by a Magnetic Nanoparticle Vector System

The sperm‐mediated gene transfer method is applicable to transgenesis in many species that use spermatozoa for reproduction recently, which has been shown various results. In the current study, we show that transgenic porcine embryos can be efficiently produced by employing a simple transfection method that uses magnetic nanoparticles (MNPs). The complexes formed between plasmid DNA and MNPs were bounded on ejaculated boar spermatozoa at a higher efficiency compared to methods using DNA alone or lipofection. Using confocal microscopy, rhodamine fluorophore‐labelled MNPs were detected on external surfaces of the spermatozoa membrane, which were bounded on zona pellucida of in vitro maturated oocyte during in vitro fertilization. Electron microscopy revealed that clusters of MNPs were detected in inside of plasma membrane and nucleus of the spermatozoa head. Additionally, we found that magnetofected boar spermatozoa could be fertilized with oocytes in vitro and that the resulting gene of green fluorescent protein was detected in fertilized eggs by genomic PCR analysis. Taken together, these results suggest that MNPs can be used to efficiently introduce a transgene into embryo via spermatozoa.     

Minimally invasive approach to lumbosacral decompression in a cadaveric canine model

AIMS: To determine efficacy of a minimally invasive (MI) surgical approach using a human MI lumbar retractor for canine lumbosacral dorsal laminectomy and partial discectomy and to compare this technique to the standard open surgical (OS) approach.

METHODS: Lumbosacral dorsal laminectomy and partial discectomy was performed on 16 large-breed canine cadavers using either a standard OS (n=8) or MI (n=8) approach. Skin and fascial incision length, procedure time, and intraoperative complications were recorded. Postoperatively specimens were evaluated for laminectomy and discectomy dimensions, and visible damage to the cauda equina and exiting nerve roots.

RESULTS: Median length of skin and fascial incisions in the OS group were longer than in the MI group (p<0.001). Median laminectomy length was similar between both approaches (p=0.234) but width was greater for the MI than OS approach (p=0.002). Both approaches achieved similar partial discectomy width (p=0.279). Overall surgical time was longer for MI approaches compared to OS, with a median of 18.5 (min 15.5, max 21.8) minutes for MI compared to 14.6 (min 13.1, max 16.9) minutes for OS (p=0.001).

CONCLUSIONS: The MI approach reduced incision lengths while retaining comparable laminectomy and discectomy dimensions. For this in vitro model the MI approach required more time to complete, but this difference may not be relevant in clinical cases.

CLINICAL RELEVANCE: Dogs undergoing lumbosacral dorsal laminectomy are commonly large-breed dogs. The traditional open approach requires a large skin incision and soft tissue dissection, especially in overweight animals. A MI approach accomplishing the same surgical result while minimising soft tissue trauma could reduce post-operative pain and recovery time, and may lower wound-related complications. Clinical studies are needed to confirm postoperative benefit and assess operating times in vivo.