Standing Laparoscopic Peritoneal Flap Hernioplasty of the Vaginal Rings does not Modify the Sperm Production and Motility Characteristics in Intact Male Horses

Laparoscopic hernioplasty techniques have been developed in the recent years to avoid the recurrence of inguinal hernias and to spare the testicles for breeding purposes in stallions. However, there have been no previous comprehensive and systematic studies of the reproductive outcomes and prognoses for stallions after inguinal hernioplasty. Therefore, the objective of this study was to assess the possible effects of one of these techniques (standing laparoscopic peritoneal flap hernioplasty) on the sperm production and motility characteristics of six healthy stallions that received this procedure based on 1‐year follow‐ups. There were no significant differences in the measured sperm variables (assessments based on the DSO, MOT, PMOT, VSL, VCL and VAP) during 1‐year follow‐ups.     

Changes in Bull Sperm Kinematics after Single Layer Centrifugation

The objective of this study was to evaluate bull sperm kinematics after centrifugation through a single layer of a colloid [Single Layer Centrifugation (SLC)]. Ejaculates from 20 bulls were extended and stored at 4–6°C for 24 h during transport to the laboratory for SLC through Androcoll‐B, followed by measurement of sperm kinematics in all samples. Total motility (86% and 88% for uncentrifuged and SLC samples, respectively) and progressive motility (84% for both the groups) were similar (p > 0.05). In contrast, straightness (STR) (0.65 vs 0.69), linearity (LIN) (0.32 vs 0.35) and beat cross frequency (BCF) (22.3 vs 23.6 Hz) were significantly higher in the SLC‐selected samples than in the uncentrifuged samples, whereas velocity of the average path (VAP) (95 vs 90 μm/s), curvilinear velocity (VCL) (192 vs 180 μm/s), amplitude of lateral head deviation (ALH) (7 μm vs 6.5 μm) and hypermotility (49% vs 38%) were significantly decreased. The kinematics of the samples with the poorest motility was improved most by SLC. In conclusion, even though SLC had no direct effect on total and progressive motility, it appeared to have a positive influence on several other kinematic parameters that may be important for fertilization after artificial insemination.     

Cytosolic calcium during contraction of isolated mammalian gastric muscle cells

During activation of visceral smooth muscle there is an increase in cytosolic-free calcium, but the source (intracellular calcium release or calcium influx), kinetics, and stoichiometry of this increase have not been determined. Here, the fluorescent indicator, quin2-acetoxymethyl ester, was used to measure directly cytosolic-free calcium during contraction of isolated stomach muscle cells induced by the two neuropeptides cholecystokinin-octapeptide and Met-enkephalin as well as acetylcholine. An increase in cytosolic-free calcium was seen that was (i) dependent on the concentration of contractile agonist, (ii) derived from intracellular sources (that is, not significantly affected by removal of ambient calcium or addition of a calcium channel blocker), and (iii) kinetically and stoichiometrically related to net calcium efflux and contraction. In contrast, the increase in cytosolic-free calcium induced by depolarizing concentrations of potassium was caused by influx of calcium through voltage-dependent calcium channels.     

Induced Spawning and Egg Quality Evaluation of Red Snapper, Lutjanus campechanus

Brood red snapper, Lutjanus campechanus, were captured from the wild and induced to ovulate by human chorionic gonadotropin (hCG) injection; eggs and sperm were manually stripped; and the eggs were artificially fertilized. Eggs were evaluated by the following egg quality parameters: buoyancy, fertilization, egg size, and oil globule size and number. The relationship of these egg quality parameters and brood characteristics (female size, fecundity, time of year, and response time to ovulation) to 36 h posthatch larval survival was considered. Injection of wild‐caught red snapper females with 1100 IU/kg of hCG resulted in 75% of the females ovulating. The average fecundity was 343,377 ± 30,805 eggs/kg, with a mean percent fertilization of 79.0 ± 1.74%. The mean percentage of floating eggs per spawn was 91.8 ± 1.75%. Mean egg diameter for floating eggs was 778.3 ± 2.09 μm, with a mean oil globule diameter of 117.5 ± 1.53 μm. Brood‐related characteristics were a better predictor of larval survival than postovulation egg characteristics. The percentage of floating eggs in a spawn was not correlated to larval survival. Spawns with eggs having a single oil globule had a similar larval survival as those eggs where multiple globules were common. No clear relationships were found for any one factor and larval survival, but rather a combination of factors was more predictive of survival, most notably spawn date, fecundity, and response time following hCG injection.     

Loss of faster-cycling soil carbon pools following grass invasion across multiple forest sites

It is established that invasive plant species can alter soil carbon cycling, although data are rare for late successional ecosystems. We examined effects of a grass invader (Microstegium vimineum) on soil carbon across eight sites in southeastern U.S. forests to establish which factors are related to these effects, by coupling isotopic and soil carbon fractionation approaches. Invasion was associated with declines in mass of faster-cycling, particulate organic matter (POM) carbon pools. This led to a significant decline (11% on average) in native-derived carbon in the surface 10 cm of the soil profile. Formation of soil carbon from the invader-derived inputs partially mitigated these losses (total carbon loss 6% on average). Our data suggest that Microstegium invasion of forest understories may accelerate carbon cycling and could result in a net loss of soil carbon from eastern U.S. forests.     

Soil fauna alter the effects of litter composition on nitrogen cycling in a mineral soil

Plant chemical composition and the soil community are known to influence litter and soil organic matter decomposition. Although these two factors are likely to interact, their mechanisms and outcomes of interaction are not well understood. Studies of their interactive effects are rare and usually focus on carbon dynamics of litter, while nutrient dynamics in the underlying soil have been ignored. A potential mechanism of interaction stems from the role fauna plays in regulating availability of litter-derived materials in the mineral soil. We investigated the role of soil fauna (meso, macro) in determining the effect of surface-litter chemical composition on nitrogen mineralization and on the micro-food web in mineral soils. In a field setting we exposed mineral soil to six types of surface-applied litter spanning wide ranges of multiple quality parameters and restricted the access of larger soil animals to the soils underlying these litters. Over six months we assessed litter mass and nitrogen loss, nitrogen mineralization rates in the mineral soils, and soil microbes and microfauna. We found evidence that the structure of the soil community can alter the effect of surface-litter chemical composition on nitrogen dynamics in the mineral soil. In particular, we found that the presence of members of the meso- and macrofauna can magnify the control of nitrogen mineralization by litter quality and that this effect is time dependent. While fauna were able to affect the size of the micro-food web they did not impact the effect of litter composition on the abundance of the members of the micro-food web. By enhancing the strength of the impact of litter quality on nitrogen dynamics, the larger fauna can alter nitrogen availability and its temporal dynamics which, in turn, can have important implications for ecosystem productivity. These findings contribute to evidence demonstrating that soil fauna shape plant litter effects on ecosystem function.     

Ovulation rate and litter size of Barbados, Targhee and crossbred ewes

Ovulation rate was measured in Barbados Blackbelly (United States strain; B), Targhee (T), Barbados X Targhee (B X T) and Barbados X Dorset-Targhee (B X DT) ewes at first and second estrus following synchronization of cycles early in the breeding season. Body weight at sponge removal differed (P less than .001) between B (30.9 kg) and T ewes (54.9 kg) and was intermediate for B X T (44.9 kg) and B X DT (43.5 kg) ewes. Ovulation rate was higher (P less than .01) at first and second estrus for B (1.86, 2.04), B X T (1.93, 2.04) and B X DT (1.72, 1.80) than for T (1.29, 1.40) ewes. Regressions of ovulation rate on body weight within the breed groups did not differ significantly from each other and the average was significant (b = .049 +/- .014 CL/kg at first estrus and b = .046 +/- .011 CL/kg at second estrus, where CL = number of corpora lutea), but differences between the groups in body weight did not explain the differences in ovulation rate. Litter size for B, B X T, B X DT and T groups was 1.71, 1.84, 1.84 and 1.28, respectively. The B X T ewes were superior to the average of the B and T ewes for ovulation rate (P less than .05) and litter size (P less than .01); there was no direct estimate of embryo survival, but the results indirectly indicate superiority of the crossbreds for this component also.(ABSTRACT TRUNCATED AT 250 WORDS)     

Feed efficiency, growth rates, body composition, milk production and milk composition of Targhee sheep selected for increased weaning weight

Lactation and growth of three contemporary lines of grade Targhee sheep developed from the same genetic base were characterized by three experiments performed over a period of 2 yr. Two lines (HW and DH) had been selected for 120-d weaning weights for 24 yr prior to beginning these experiments. A third line (C) was a randomly selected control. Year I experiment contrasted 10 DH with 7 C ram lambs fed to 58 kg. Year II experiments utilized 9 C, 14 DH and 10 HW ram lambs and 11 ewes suckling twins from each line. All Year II ram lambs were born and weaned as twins, then fed to 50 kg. Mature DH and HW ewes were heavier (P less than .05) than C ewes (65.2 and 68.8 vs 54.9 kg), and the DH and HW lambs grew faster than C lambs both before (P less than .05) and after weaning (P less than .05). While both DH and HW lambs drank more milk (2,419 and 2,368 vs 2,059 g X d-1 X pair-1; P less than .10) only HW ewes showed a trend towards greater potential milk production than controls (HW = 2,774 vs C = 2,155 g X d-1 X ewe-1 P less than .12). The HW lambs tended to be leaner than C lambs (P less than .05), but DH lambs did not differ from either line. Lambs from DH and HW lines required less post-weaning feed (121.9 and 129.3 vs 152.0 kg P less than .05) and exhibited 17 and 16% greater weight per day of age at 50 kg than controls (P less than .05). The DH line displayed lower feed: gain ratios than controls in both post-weaning trials (6.68 vs 7.30 to 58 kg; 5.83 vs 6.24 at 50 kg; P = .06).     

Plasma indicators of muscle damage in a model of nutritional myopathy in weaner sheep

SUMMARY Subclinical nutritional myopathy was induced in 5-month-old sheep by feeding them a diet low in vitamin E and selenium. Subsequently clinical myopathy was induced by dosing with protected polyunsaturated fatty acids. Plasma activities of creatine kinase (CK), pyruvate kinase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase and aldolase, enzymes of muscle origin, all remained above their reference ranges in clinically affected sheep, but fluctuated widely. Similar fluctuations occurred in subclinically affected animals, resulting in some activities being within the reference ranges and some above, at different times. Plasma malondialdehyde, an indicator of lipid peroxidation, proved of no diagnostic value. Terminal plasma CK activities were significantly correlated with microscopic damage in the vastus lateralis (VL), but not the vastus intermedius (VI) or the tensor fascia lata (TFL) muscles. AST was the most highly correlated with damage in VI and VL. In two clinically affected sheep successfully treated with an oral dose of α-tocopherol actetate all enzymes decreased steadily to within their reference ranges, at rates probably related to their plasma half-lives. These results suggest that measurement of plasma CK activity would be useful in monitoring recovery of treated sheep.