The viability and performance under hot conditions of featherless broilers versus fully feathered broilers.

Hot conditions decrease the difference between ambient temperature (AT) and the average temperature of the body surface. A smaller difference reduces the rate of sensible heat loss of excessive internal heat, elevates the body temperature (BT), and may lead to mortality during heat waves. Under conditions of chronic heat, broilers avoid lethal BT elevation by reducing their feed intake; consequently, growth rate and meat yield are lower. Practices to avoid hot conditions are costly, whereas breeding for heat tolerance offers a sustainable approach. Being featherless was shown to provide heat tolerance; this was reevaluated in experimental broilers with a growth rate similar to that of contemporary commercial broilers. In experiment 1, 26 featherless birds and 49 feathered siblings (sibs) were reared at warm AT and exposed to moderate and acute heat waves. The featherless birds maintained normal BT under a moderate heat wave, with a slight elevation under an acute heat wave, and only 1 bird died. In contrast, the heat waves led to a significant elevation in BT of the feathered sibs, and 34% of them died. In experiment 2, featherless broilers were compared with feathered sibs and commercial broilers at 2 AT treatments: a constant temperature of 25°C (control AT) or a constant temperature of 35°C (hot AT). The birds were reared to 46 or 53 d at the control and hot AT, respectively, and the measured traits included BT, growth, and weight of the whole body and carcass parts (breast meat, legs, wings, and skin). At the hot AT, only the featherless broilers maintained a normal BT; their mean d 46 BW (2,031g) was significantly higher than that of birds maintained at the control AT, and it increased to 2,400 g on d 53, much higher than the corresponding means of all feathered broilers (approximately 1,700 g only). Featherless broilers had significantly higher breast meat yield (approximately 20% in both AT), lower skin weight, and supposedly better wing quality. These results confirmed that being featherless improved the livability and performance of fast-growing broilers in hot conditions and suggests that introduction of the featherless phenotype into commercial broiler stocks would facilitate highly efficient yet low-cost production of broiler meat under hot conditions.

Magnetized spiral chains of plasmonic ellipsoids for one-way optical waveguides.

When a linear chain of plasmonic nanoparticles is subject to longitudinal magnetic field, it exhibits optical Faraday rotation. If the magnetized nanoparticles are plasmonic ellipsoids arranged as a spiral chain, the interplay between the Faraday rotation and the geometrical spiral rotation (structural chirality) can strongly enhance nonreciprocity. This interplay forms a waveguide that permits one-way propagation only, within four disjoint frequency bands, two bands for each direction.

Growth rate of ascites-resistant versus ascites-susceptible broilers in commercial and experimental lines.

The high growth rate (GR) of contemporary broilers is driven by high rate of feed intake and metabolism. Because of the consequent high oxygen demand, especially when coupled with exposure to high altitude or low temperatures, some broilers fail to regulate oxygen supply and develop the ascites syndrome (AS), which leads to mortality and economic losses. Because of the association between high GR, oxygen demand, and AS, it has been suggested that AS is induced by high GR. If true, further GR enhancement should be avoided because it will increase the proportion of AS-susceptible individuals in contemporary stocks. An alternative hypothesis claims that AS is associated with high actual GR only because the latter increases oxygen demand and that there are genetically AS-resistant broilers that do not develop AS, even when exhibiting high GR. These hypotheses were tested in trials in the years 2002 and 2006, with broilers differing in potential GR: contemporary fast-growing commercial lines and an experimental line derived from commercial broilers in 1986, and (in 2002 only) divergently selected AS-susceptible and AS-resistant lines. A protocol of high-challenge ascites-inducing conditions (AIC) from d 19 was used to distinguish between AS-susceptible and AS-resistant individuals and to determine their GR up to this age. The difference in AS incidence between the divergent lines (93.9 vs. 9.5%) was not explained by the 5% difference in their GR, thus indicating a lack of genetic correlation. In the broiler lines, AS incidence was 31 and 47% in 2002 and 2006, respectively, and 32% in the 1986 slow-growing line. Most broilers that remained healthy under the high-challenge AIC exhibited the same early GR and BW as those that later developed AS. These results, and the relatively high incidence of AS in the slow-growing line, indicate that there is very little, if any, direct genetic association between AS and genetic differences in potential GR, and suggest that AS-resistant broilers can be selected for higher GR and remain healthy even under AIC.

In vivo exposure to Porphyromonas gingivalis up-regulates nitric oxide but suppresses tumour necrosis factor-alpha production by cultured macrophages.

The present study was designed to test whether the functional response of mouse macrophages elicited by chronic exposure to bacteria will be different from that of cells elicited by a non-bacterial irritant. Macrophage elicitation was conducted by Porphyromonas gingivalis, a major periodontal pathogen, in comparison to a standard elicitation by thioglycollate (TG). We measured lipopolysaccharide (LPS)-induced nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha) secretion by the elicited macrophages, and the expression of inflammatory cytokines in the whole elicited cell population. In addition, we tested the response of TG-elicited macrophages to pretreatment with P. gingivalis LPS in vitro. Mouse peritoneal macrophages were harvested 4 days after intraperitoneal injection of TG or heat-killed P. gingivalis. TG-elicited macrophages produced undetectable levels of TNF-alpha and approximately 0.5 microM of NO. The stimulation of the macrophages with LPS resulted in the secretion of NO and TNF-alpha in a dose-dependent manner. The P. gingivalis-elicited macrophages produced basal levels of approximately 5 microM NO, but TNF-alpha was not detectable. LPS stimulation of these cells further increased the secretion of NO eightfold while TNF-alpha remained undetectable. The NO secretion by P. gingivalis-elicited cells was significantly higher than that by TG-elicited cells. Examination of cytokine expression in the whole elicited cell population revealed that both P. gingivalis-elicited cells and TG-elicited cells expressed messenger RNA for interleukin-2 (IL-2), TNF-alpha and interferon-gamma (IFN-gamma), but not for IL-4. IL-6 was expressed in P. gingivalis-elicited cells only. Pretreatment of TG-elicited macrophages with P. gingivalis LPS for 24 hr prior to a second LPS challenge resulted in down-regulation of TNF-alpha secretion and up-regulation of NO secretion, a response similar to that seen in P. gingivalis-elicited peritoneal macrophages. The results suggest that the in vivo exposure of resident macrophages to P. gingivalis induces functional changes in peritoneal macrophages. These changes might be due to the effect of P. gingivalis LPS.