The effects of artificially-induced fly-strike on food intake and liveweight gain in sheep

A single, artificially-induced fly-strike with Lucilia sericata larvae was associated with a rapid (decline in food intake in sheep, with a consequent reduction in liveweight. Loss of weight ranged from 0.5 to 5.5 kg over four to six days and recovery to pre-infestation liveweight took three to 36 days. Pair-fed, uninfested partners of these sheep also showed a reduction in liveweight, whereas uninfested sheep in some experiments fed ad libitum showed either little change or a gain in liveweight over the same period. In general, maggot infested sheep took less time to regain weight than did their pair-fed partners although the weight lost as a proportion of initial weight was similar in both groups. Loss of appetite alone would appear to account for these events.     

The osmolality of caecal contents in piglets following weaning

Pigs weaned for five days had caecal contents with significantly lower osmolalities than those of unweaned animals of the same age. Supplementation of a standard weaning diet with therapeutic levels of oxytetracycline to suppress the normal large intestinal microbial flora did not significantly further reduce osmolarity of caecal contents after weaning. This observation suggests that microbial activity in the large intestine may not be sufficiently developed by five days after weaning to have a major influence on absorptive processes at that site. Incomplete development of the large intestinal microflora may be one more factor which acts to predispose the young pig to diarrhoea after weaning.     

The effects of nutrient solution sterilization on the growth and yield of hydroponically grown lettuce

Two methods of removing bacteria from hydroponic nutrient solution [ultraviolet (UV) radiation and submicronic filter] were evaluated for efficiency and for their effects on lettuce (Lactuca sativa L.) production. Both methods were effective in removing bacteria; but, at high intensity, the ultraviolet sterilizer significantly inhibited the production of plants grown in the treated solution. Bacterial removal by lower intensity UV or a submicronic filter seemed to promote plant growth slightly, but showed no consistent, statistically significant effect.     

The structure of bovine secretory component

Bovine secretory component (SC) has been cleaved with trypsin into a series of fragments and their N-terminal amino acid sequences have been determined. The close homology with the known sequence of human SC has enabled the sequential order of the fragments to be deduced. The results indicate that bovine SC consists of a single glycosylated polypeptide chain (Mr 74,000) folded into five globular immunoglobulin-like domains. A protein (Mr 94,000) has been isolated from detergent solubilised bovine epithelial membranes from liver, intestine and mammary gland. This membrane protein is specific for the binding of J-chain linked IgM and IgA dimers. It can be proteolytically cleaved into a water soluble SC-like portion and a detergent soluble hydrophobic portion. Bovine SC is therefore most likely to be the extracellular part of an epithelial receptor which mediates the transport of IgA dimers to mucosal surfaces. The various tryptic fragments from bovine SC have been shown to differ in their relative binding affinities for IgM and IgA dimers. The results imply that the first three domains of bovine SC are most involved in binding and domains 4 and 5 play subsidiary roles. Computerized prediction and modelling methods have been used to deduce possible tertiary and quaternary structures for SC. There are good indications that the molecule has an elonaged "zig-zag" structure stabilized by longitudinal inter-domain contacts. A model of SC bound to IgA dimer is presented.     

Determination of bacterial N portions in feces and differently collected ileum chymus from swine]

In faeces and ileal digesta samples of 31 intact (INT) as well as 73 surgically differently prepared pigs bacterial fractionations and 2.6-diaminopimelic acid (DAP) estimations were carried out in order to calculate the bacterial N proportion in faeces N and digesta N after feeding various diets. Because of a high individual variability and the analytical variation width of the DAP/N-ratios no distinct influences of the fed diets could be found. The average DAP/N-values in the faeces (0.224) of INT pigs ranged in the same magnitude as in the digesta (0.0272) of ileorectostomized (IRA) pigs with open colon descendens (IRAo), where a digesta backflow is possible. Distinct lower DAP/N-ratios (0.0125 resp. 0.0043), however, were found in the digesta of pigs with ileo-caecal cannulae (IZB) or IRA pigs with closed colon (IRAg). On the base of various premises (N of the "bacterial fraction" C is only bacterial N; the DAP found in fraction A originates from intestinal bacteria adhering to feed particles) conducted calculations of the bacterial N proportions (in per cent of total N) led to the following data: Faeces of INT pigs: 43.0 ... 68.2 vs. 69.6 ... 89.0; digesta of operated pigs (except protein free diet) IRAo: 22.3 ... 57.0 vs. 46.2 ... 73.8; IZB: 17.0 ... 35.7 vs. 25.2 ... 53.6; IRAg (only 3 pigs): 23.6 vs. 24.2. The proportion of bacterial N in the digesta N of protein free fed IRAo pigs was 22.0 vs. 22.6%.