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Poultry processing establishments use antimicrobial aids on broiler parts to minimize Campylobacter contamination. A silver-stabilized hydrogen peroxide (SHP) product was assessed for use as an antimicrobial processing aid. In a series of experiments, wing segments with skin were inoculated with 103 to 107 cells of Campylobacter coli, followed by treatment with SHP at 15,000 or 30,000 mg/L, peroxyacetic acid (PAA) at 300 or 3,000 mg/L (parts per million), or water. Each treatment was applied by either dip or spray. Rinsates from each wing segment were analyzed for direct counts and prevalence of Campylobacter. Treatment with SHP or PAA significantly reduced Campylobacter levels compared with water controls by up to 2.22 log CFU/mL. At high inoculum levels (106 to 107), SHP and PAA applied by dip had up to 1.27 log CFU/mL further reductions of Campylobacter levels compared with spray-treated wing segments. Additionally, wing drumettes were observed to retain higher levels and prevalence of Campylobacter recovery compared with wing flats at a low inoculation level (103). The results indicated that there was no carryover effect of SHP (same day versus 24 h) and dip treatment with SHP or PAA decreased Campylobacter recovery on broiler chicken wing segments compared with a water control. Although a 2-log reduction was modest, SHP had similar efficacy as the commonly used processing aid PAA. SHP shows potential for further investigation as an antimicrobial processing aid for use on poultry parts. HIGHLIGHTS

A variety of methods have been utilized for gene transfer to the cells of the airway epithelium. These have included DNA-mediated mechanisms of gene transfer as well as recombinant viral vectors. Despite the availability of these methods, limitations in their utility warrant the development of alternate systems. As an alternative, receptor-mediated endocytosis using transferrin-polylysine conjugates has been shown to transduce immortalized airway epithelial cells efficiently via a physiologic pathway. When transferrin-polylysine conjugates were used to transduce airway epithelial cells grown in primary culture, however, gene transfer occurred inefficiently. Investigation into this relative inefficiency centered on endosomal entrapment of the conjugate-DNA complex. Pretreatment of the cells with chloroquine, which causes vacuolization and disruption of the endosome, or co-delivery of adenoviral particles, which serves to lyse the endosomal membrane, were both associated with greatly improved gene transfer efficiency. These studies established that the relative refractory state of the airway epithelial cells in primary culture was secondary to the retention of the internalized material within the endosome. We thus explored the efficiency of conjugates that possessed a mechanism to escape this endosomal entrapment; adenovirus-polylysine conjugates and transferrin-polylysine/adenovirus-polylysine conjugates were thus employed. Gene transfer efficiency improved significantly with the adenovirus-containing conjugates. These data support the concept that conjugates can be synthesized that mediate highly efficient gene transfer to airway epithelial cells in primary culture via the receptor-mediated endocytosis pathway.

Adenovirus–polylysine–DNA complexes were evaluated for their capacity to accomplish direct in vivo gene transfer to airway epithelium employing a rodent model. Binary complexes containing transferrin or adenovirus, or combination complexes containing both transferrin and adenovirus, were evaluated. The highest in vitro gene transfer efficiency in primary cultures of airway epithelial cells was accomplished by the combination complexes. This result was paralleled in vivo. Transient gene expression of up to 1 week was observed with localization of the transduced cells to the region of the small airways. These results establish the feasibility of this type of approach for gene therapy applications.

Inflorescence-bearing tillers of Italian ryegrass (Lolium multiflorum cv. RvP) were dried in controlled temperature, relative humidity and air speed conditions chosen to be within the range likely to occur in a hay swath drying in the field. After drying for increasing intervals the tillers were separated into inflorescence, exposed flowering stem, leaf-laminae, leaf-sheath and flowering stem enclosed by leaf-sheath and the drying rates of these components in addition to that of whole tillers were measured. There were large differences in drying rate between components, but the differences were similar over the range of drying conditions employed. The drying rate of the inflorescence as well as that of stem enclosed by leaf-sheath was found to be very low and that of leaf-laminae and leaf-sheath very high.

SUMMARYThe drying rate of leaves and stem internodes from flowering culms of two varieties of Italian ryegrass (Lolium multiflorum) were measured in the laboratory in controlled conditions of temperature (28 °C), relative humidity (22%) and air speed (40 cm/sec), without treatment, or after being subjected to thermal treatment or to mechanical damage followed by thermal treatment. The two treatments increased the drying rate of leaves and, to a greater extent, stem internodes.While it cannot be concluded that all treatments that increase crop drying rate will increase the rate for stems more than for leaves, these results are considered to indicate the possibility of devising practical treatments which will. Such treatments could reduce leaf shatter and consequent serious loss of dry matter during the field drying of grass crops.

An apparatus is described which enables excised pieces of plant material lo be weighed al frequent intervals as they dry in controlled conditions of temperature, humidity and air-speed. The effect of removing the epidermis on the drying rate of red clover (Trifolium pratense) leaflets, leaf petioles and stems is examined. Initially this treatment caused a very large increase in the drying rate of leaflets. Although the effect declined as water content fell, leaflets from which the epidermis had been removed still dried more rapidly than the controls at a water content equivalent to 50% of the dry weight. Removing the epidermis had a greater effect on the drying rate of leaf petioles and stems at low water contents than it did on the drying rate of leaflets. Slow drying at low water contents is a major factor responsible for the undesirably long periods for which hay may lie in the field. Slow drying occurs even though swath microclimate becomes more favourable for drying as water content falls. The results presented here suggest that treatments which reduce cuticular resistance have the potential to reduce field drying time.

Pure swards of S22 Italian ryegrass, H.1 hybrid ryegrass, S170 tall fescue, S48 timothy, S215 meadow fescue and Germinal cocksfoot were each harvested at several stages of maturity during first growth in the spring, and in the subsequent regrowths. Each batch of herbage was fed to sheep in a digestion trial under conditions of voluntary intake. Results from the first growth herbages showed the expected fall in digestibility with increasing maturity. However, the digestibility of S22, H.1, S170 and S48 began to fall well before ear emergence, whereas the digestibility of Germinal fell only slowly up to the time of ear emergence, as had been found previously with S24 and S23 ryegrass and S37 cocksfoot. The rate of fall of digestibility in H.1 and S48 (0.4 units/day) also appeared to be lower than with the perennial ryegrasses and cocksfoot (0.5 units/day). The monthly regrowths within each herbage were of similar digestibility, but the mean digestibility of regrowths differed between herbages, being highest for S215 and lowest for Germinal and S170. The grasses with highest digestibility in the early Spring, in particular S22 ryegrass, were not, however, always the most digestible in the subsequent regrowths. The numbers of sheep fed on each herbage were insufficient to show whether there were significant differences in voluntary intake between different herbage species of the same digestibility. It is suggested that an intake/digestibility relationship, based on data from more animals, should be developed for each herbage species. Only if different relationships are found can it be concluded that factors other than level of digestibility have an effect on intake.

SUMMARYThe voluntary intake by sheep of seventy silages was measured in experiments in several years. Linear and multiple regression analyses were made between these voluntary intakes and the contents of dry matter, various acids and nitrogen and the digestibility value determined in vivo. There were some differences in these relationships for silages made from different groups of species, particularly those made from legumes. Voluntary intake was positively correlated with the contents of dry matter, nitrogen, lactic acid as a percentage of total acids and with the Flieg index. Voluntary intake was negatively correlated with the contents of acetic acid and ammonia as a percentage of total N. Although pH alone did not account for a significant part of the variation in intake, multiple regressions in which pH and one of the measurements of fermentation quality were included were significant, with pH positively related to intake. When all silages were considered, the correlation between voluntary intake and the apparent digestibility of dry matter was not significant. However, for legumes this correlation was significant and positive and for grasses other than ryegrass the correlation was significant and negative.

This paper presents the results of 125 digestion trials with sheep fed herbage at different stages of growth from three clover-free pure grass swards. During 1958 and 1959, a study was made of the yield, leaf lamina, nitrogen, ash and digestible organic matter percentage (D) of first growths, of regrowths cut at monthly and two monthly intervals and of swards receiving various quantities of fertilizer nitrogen. For first growths in the spring D remained almost constant until the ears started to protrude from the leaf sheaths and then fell rapidly at approximately 0·5 per cent per day. The D values for S 23 ryegrass were three weeks later than S 24 ryegrass, which correspond with later ear emergence of the latter. S 37 cocksfoot was always less digestible than S 24 ryegrass although both were at similar stages of growth. This difference in D also occurred in the regrowths. The D of monthly regrowths tended to fall with each successive cut, although in 1959 ryegrass values improved in the autumn. Fertilizer nitrogen had little effect on D. Despite the warmer spring and drier summer in 1959 and corresponding changes in production per acre there was little effect on D.

SUMMARY Water loss from cut grass was studied to determine factors limiting the drying process. An apparatus, used to measure water loss at 28±1°C from blotting paper and from leaves and stem internodes of cocksfoot, consisted of four channels in which air speed was controlled at 25–80 cm s-1 and relative humidity at 7–68%. The maximum rate of water loss from wet blotting paper was 10500 mg water dm-2 h-1 but from leaves and stem internodes supplied with water it was less than 250 mg dm-2 h-1. The rate of loss from both plant specimens and blotting paper was linearly related to the vapour pressure differences between the specimen and the surrounding air but was not increased when air speed was changed from 40 to 80 cm s-1. Grass specimens supplied with water had lower rates of water loss than wet blotting paper because of tissue resistances which were calculated for (a) untreated leaf and stem specimens, (b) rubbed leaves, (c) cut leaves, (d) leaves exposed to steam for 60 s. Treatments (b)-(d) greatly reduced tissue resistances. The rates of drying of leaves and stem internodes not supplied with water changed only slightly in response to faster air speeds but were significantly increased by treatments (b), (c), (cs) (split stems), (d) and (e) (exposure to petroleum vapour for 60 s). The most effective treatments trebled the drying rates of leaves and increased the drying rates of stem internodes by 10 times. Reductions in relative humidity had little effect on drying rate following treatments (a), (b), (c) and (d), but when treatments (cs) and (e) were given, additional significant increases in drying rates were obtained when the relative humidity was reduced. Grass specimens given the most effective treatments and dried under the most favourable conditions did not utilize the full drying capacity of the environment, for the rates of water loss from these specimens were at least three times lower than those from wet blotting paper. The results indicate that high rates of drying could be achieved at 28 oC or similar temperatures if practical treatments were developed to remove or greatly reduce the high resistance to water loss in cut grass.

SUMMARYThe dry-matter and organic-matter digestibilities of eight samples of fodder maize and five samples of maize silage were measured, using sheep. The maizes were harvested and ensiled in such a way that comparisons could be made between the digestibilities of either the same maturity types, harvested on different dates, or of different maturity types harvested on the same date, or of maize and silage made from similar material. The total range of organic matter digestibility for all types of maize on all dates was within the range 70·6 to 75·2 per cent. The digestibilities of maize silages were found to be slightly lower than those of the original materials.

GnRH interacts with a plasma membrane receptor to provoke gonadotropin release, as well as regulate numbers of its own receptor and target cell responsiveness. Receptor numbers are altered in different physiological states of the animal. Microaggregation of the GnRH receptor mimics all known actions of the releasing hormone, and therefore is viewed as an early step in the molecular mechanism of hormone action. Internalized hormone is neither necessary nor sufficient for stimulation of known releasing hormone actions. Evidence summarized in the present work suggests that Ca2+ serves a role as a second messenger for GnRH-stimulated gonadotropin release, and that it may be involved in receptor up-regulation in response to the releasing hormone. In the former role, diacylglycerols by their action on protein kinase C, in a fashion independent of the Ca2+ -calmodulin system, may act as a signal amplifier.