The production of milk rich in protein and low in fat, the fat having a high polyunsaturated fatty acid content

In two experiments, dairy heifers were offered a basal diet of ground dried grass cubes and flaked maize. In Experiment 1, the diet contained equal amounts of these components whereas, in Experiment 2, the proportions were varied from all-grass to equal amounts of grass and flaked maize. Before and after the main part of each experiment, the animals were offered a diet containing hay, molassed sugar beet pulp and barleybased concentrates. Compared to this diet, the grass cubes-flaked maize diet reduced the fat content of the milk and increased the crude protein content. The proportions of all the milk fatty acids up to 18:0 were reduced and those of 18:1, 18:2 and 18:3 were increased. In Experiment 1, the basal diet of grass cubes and flaked maize was supplemented with 180 and 360 g day^?1 soya bean oil given as crushed, unextracted soya beans or with 180 g day^?1 soya bean oil given as a formaldehyde-treated caseinoil preparation but none of these supplements had any effect on the composition of the milk. In Experiment 2, the crude protein content of the milk increased as the proportion of flaked maize in the diet was increased. Otherwise, there were no differences between the different diets.     

The yield,fatty acid composition and physical properties of milk fat obtained by feeding soya oil to dairy cows

The presence in the bovine mammary gland of a desaturase specific for the conversion of stearic to oleic acid allows the manipulation of the physical properties of milk fat by varying the dietary intake of C₁₆ and C₁₈ fatty acids. In particular, feeding the dairy cow an oil with a high C₁₈: C₁₆ ratio should allow the proportion of milk fat that is liquid at 5°C to be increased, with a consequent improvement in the low-temperature spreadability of butter. In this paper, the effect of feeding concentrate rations containing (a) soya oil as the free oil and as cracked soya beans; (b) various levels of soya oil, the ration being offered twice or 24-times daily, on the thermal properties of the milk fat and on the yield of milk constituents is examined in detail. Feeding ratios containing free soya oil greatly increased the proportion of milk fat liquid at 5°C, whereas cracked soya oil gave only slight increases. Proportion and yield of milk fat were decreased by feeding soya oil twice daily but were increased by continuous feeding.     

Whey protein aggregate formation during heating in the presence of κ-carrageenan

The effect of a negatively charged polymer, κ-carrageenan, on the aggregation behaviour of whey proteins during heating was studied. Aqueous solutions of whey protein isolate (WPI) at 0.5% were heated in the presence of κ-carrageenan (0.1%) at pH 7.0. This concentration was chosen as optimal in the detection of the intermediate aggregates during chromatographic analysis. The residual unaggregated protein, the intermediate aggregates and the soluble aggregates were all examined as a function of heating time and temperature, using size-exclusion chromatography coupled with light scattering detection. The presence of κ-carrageenan did not affect the aggregation of whey proteins heated at 75 °C; however, a change in the mechanism of aggregation seemed to occur at higher temperatures, and intermediates with higher molecular mass formed at 85 °C. At 90 °C, in the presence of κ-carrageenan, the extent of WPI aggregation was much larger, as soluble aggregates were no longer present and less residual protein was recovered in the unaggregated peak.     

Preservation of gastrointestinal bacteria and their microenvironmental associations in rats by freezing

The use of frozen rat gastrointestinal tissue samples for both the recovery of viable bacteria and for observation of microbial communities associated with the tissue was investigated. A decrease of 1 log in lactobacilli, bifidobacteria, and anaerobes was observed when the numbers of bacteria recoverable from frozen tissue (stored 7 to 9 days) were compared to those recoverable from fresh nonfrozen tissue (zero time control). However, freezing did not appear to decrease the numbers of recoverable coliforms. Tissues, cleaved with razor blades after being frozen and stored for 7 to 9 days, showed bacterial communities situated on the mucosa and in the lumen of gastrointestinal specimens. This freezing technique preserved structures not previously observed in the gastrointestinal tract. This indicates that freezing is a good method to use to study such fragile microenvironments.     

Levels of prostaglandins in the small intestine of rats during primary and secondary infection with Nippostrongylus brasiliensis

The level of PGE is increased 10-fold in intestinal tissues during primary infection of the rat with Nippostrongylus brasiliensis. Peak levels (ca. 7,000 pg/cm) were assayed in the jejunal site of infection on day 7 of infection and similar levels were recorded in 'post-infection' (ileal) segments at this time. The level of PGE in 'post-infection' segments showed further increase to 12,000 pg/cm on day 10. The level of PGE also increased in 'pre-infection' (duodenal) but this was delayed by 4-5 days. The level of PGF also increased during primary infection (from about 100 to 950 pg/cm) but this occurred after expulsion. Increase in the level of PGE occurred earlier (at 3-4 days) during secondary challenge given 19 days after primary infection, but the PGE levels followed the primary response when challenge was given 10 weeks after primary infection. It is suggested that PGE plays a dual role in parasite immunity. (1) PGE may directly affect metabolism of the parasite. In this event it is also suggested that protective antibodies cause the release of PG. (2) Elevated levels of PGE act indirectly by affecting gastrointestinal function which alters the microenvironment at the site of infection. The duodenal migration of parasites may be due to this effect of PGE.     

Mucocutaneous lymph node syndrome

Mucocutaneous lymph node syndrome represents a series of clinical findings that has been observed primarily in Japanese children. The disease now appears to be migrating to this country. It involves the cervical lymph nodes, the skin, and mucus membranes. Although the course is usually benign and self-limiting, a number of deaths have resulted from coronary artery disease.     

The in vivo effect of colchicine on the addition of galactose and sialic acid to rat hepatic serum glycoproteins

Colchicine inhibits the secretion of plasma protein by rat hepatocytes and causes their intracellular accumulation in Golgi-derived secretory vesicles. This study examines whether colchicine affects secretion before or after galactose and sialic acid have been added to the secretory glycoproteins. D-[G-3H] Galactose was injected into rats and was found to be incorporated into serum glycoproteins contained within Golgi-derived secretory vesicles. The administration of colchicine (25 mumol/100 g, body weight), immediately before the injection of D-[G-3H] galactose, caused an increase in radioactivity of the serum glycoproteins in these cell fractions. D-[G-3H] Glucosamine was incorporated into serum glycoproteins contained within the rough and smooth endoplasmic reticulum and the Golgi cell fractions; however, its incorporation into the sialic acid moieties of these proteins only occurred in Golgi-derived cell fractions. Colchicine administration resulted in an increased incorporation of D-[G-3H] glucosamine into the sialic acid residues of serum glycoproteins contained within the Golgi cell fractions. These data indicate that colchicine inhibits secretion of serum proteins by rat liver after the addition of galactose and sialic acid to the secretory proteins has taken place.     

Treating Pseudomonas cepacia meningitis with trimethoprim-sulfamethoxazole

An infant with neonatal meningitis caused by Pseudomonas cepacia responded promptly to treatment with trimethoprim-sulfamethoxazole (Bactrim) after other abtibiotics had failed. Pseudomonas cepacia has proven to be resistant to most of the commonly used antibiotics.