Inclusion of antibiotics in feed alters greenhouse gas emissions from feedlot manure during composting

In this study, the effects of dietary inclusion of antibiotics on emissions of greenhouse gases (GHG: CO₂, CH₄ and N₂O) from cattle manure during composting were investigated. Manure was collected at the end of two feeding trials in 2005 and 2006 in which feedlot cattle were assigned to one of five dietary groups: (1) Control: no antibiotics added; (2) TYL11: tylosin at 11 mg kg⁻¹ feed; (3) CTC11: chlortetracycline at 11 mg kg⁻¹ feed; (4) CTC44: chlortetracycline at 44 mg kg⁻¹ feed; and CTC44SMZ44: chlortetracycline and sulfamethazine, each at 44 mg kg⁻¹ feed. Open windrows were constructed and the rate of GHG emission was measured periodically. In both years, CO₂ surface emissions were higher (P < 0.05) for treatments CTC11 and CTC44SMZ44 than for the Control. The CO₂ emission rates in 2005 were lower (P < 0.05) than in 2006, reflecting lower total carbon (TC) content in the manure in 2005 (138 ± 2 g kg⁻¹) than in 2006 (245 ± 2 g kg⁻¹). The rate of CH₄ emission varied from 0.006 to 0.232 g C m⁻² day⁻¹. Average values from all four antibiotic treatments were similar (P > 0.05) to the Control in both years. The N₂O emission rates were higher (P > 0.05) with CTC44SMZ44 (2005), TYL11 (2006) and CTC11 (2006) than with Control. While antibiotics do alter GHG emissions from composted feedlot manure, the mechanisms responsible are not clear and warrant further investigation.     

Factors affecting length of herdlife in purebred and crossbred dairy cattle

The proportional hazards model with censoring was used to assess the effects of breeding value, disease, calving, size, and udder and lactation traits on length of herdlife of 3881 heifers in five herds. Data were recorded over 10 yr from three lines: a Holstein line, an Ayrshire-based line, and a crossbred line. Influences on survival were assessed from data collected at birth, 34, 50, and 82 wk, first freshening, and at 112 and 308 d postpartum. Median estimated herdlife (age at 50% culling) was 3.9 yr for animals alive at first freshening and increased to 4.3 yr for those that completed a first lactation (308 d postpartum). Herds differed greatly in the pattern of culling after freshening. Crossbred females had 21 wk longer median estimated herdlife than the mean of the purelines at 308 d postpartum. Individual milk yield was positively associated with longevity and had the greatest impact on length of herdlife. Abortion and fertility measured as days to last insemination were negatively associated with length of herdlife. Large heifers tended to have increased longevity. High feed intake postpartum was associated with reduced length of herdlife. Objective measures of conformation, which included measurements of the udder, were not important in determining herdlife.     

Growth and feed efficiency of pureline and crossline dairy heifers

Data on 3957 heifers from the Holstein H line, Ayrshire-based A line, and C line (crossbreds between H and A lines) were used. Growth, feed consumption, and feed efficiency from 26 to 34 wk were examined. The full model included the fixed effects of herd, year of birth, season of birth, and additive, maternal, and heterotic genetic effects with 26-wk weight as a covariate. Heterotic and maternal effects were not significant. Adjusted for the 26-wk weight covariate, H line heifers gained 3 kg more than A line heifers with C line heifers intermediate. Adjusted for 26 and 34-wk weight covariates, H line heifers ate 2 kg less TDN than A line heifers and, hence, were more efficient. Correlations among traits were estimated using the residual variance-covariance matrix from the full model. Body weight at 34 wk was correlated with 26-wk weight (r = .88) but essentially independent of rate of gain (r = .02). It was correlated with feed consumed (r = .51) and negatively associated with gain/feed consumed (r = -.25). Gain was correlated (r = .84) with gain/feed consumed but mildly so (r = .28) with feed consumed. Feed consumption was negatively correlated (r = -.25) with gain/feed consumed when the 26-wk weight covariate was included but became much larger (r = -.95) when both 26 and 34 wk weight covariates were included. Although genetic differences in feed consumption and feed efficiency of growing heifers exist, these are small and closely associated with weights and weight gains.     

Influence of bulk dielectric polarization upon partial discharge transients: effect of void geometry and orientation

The induced charge arising from a partial discharge consists of 2 components. One is associated with the actual space charge in the void. The other is related to changes in the polarization of the bulk dielectric. These changes are a direct consequence of the field produced by the space charge. The influence of the void geometry upon the polarization component of the induced charge is examined for a heterogeneous bulk dielectric system. It is demonstrated that, depending on the ratio of the dielectric permittivities and within which dielectric the void is located, the relative magnitude of this component may increase or decrease. The magnitude of this effect is also strongly dependent upon the prolateness/oblateness of the void geometry, and on the orientation of the void with respect to the detecting electrode.     

Effect of high fat corn oil, olive oil and fish oil on phospholipid fatty acid composition in male F344 rats

Venous stasis associated with prolonged bed rest can enhance the risk of deep venous thrombosis (DVT). Pneumatic compression of the lower extremities can reduce this risk by preventing venous stasis. When selecting a method of leg compression for their patients, physicians must chose between two distinctly different types of compression devices. One device applies pressure with a single-chambered sleeve to the below knee region while the other applies pressure in a sequential gradient fashion from the ankle to the thigh. The current prospective study was designed to evaluated the ability of two such devices to increase blood flow in the profunda femoral vein. Venous blood flow velocity, compression time, and vein diameter were measured in nine normal experimental subjects using an Accuson duplex-Doppler before, during and after leg compression. Compression with the single-chambered device produced a significant rise in venous blood flow velocity; however, this could not be maintained and our results indicate a higher average velocity was achieved with the sequential gradient device. The sequential gradient device also moved a greater volume of blood and achieved a higher average blood flow rate. The time between deflation of the sleeve and return of a phasic respiratory signal was greater after compression with the sequential gradient device. These results suggest that sequential gradient compression produces the type of hemodynamic alterations needed to reduce the risk of DVT by achieving a sustained increase in venous blood flow and more completely emptying of the veins in the leg.