Biomedical subjects

K J Jenkins

Publications and source records attributed to K J Jenkins.

At least 55 records · Page 3Linked to original sources

PubMed1988

Effect of excess dietary iron on lipid composition of calf liver, heart, and skeletal muscle.

Effect of excess dietary iron on lipid composition of calf liver, skeletal muscle, and heart was assessed. High dietary iron (5000 versus 100 ppm in milk replacer DM) had no effect on the relative proportion of lipid classes in liver or their unsaturated fatty acid composition. In muscle some minor lipid components were reduced and cholesterol and sphingomyelin increased. Excessive iron had a marked effect, however, on heart lipid composition, reducing total lipids and almost all lipid classes; triglycerides, sphingomyelin, and lysophosphatidylcholine were increased. Characteristically, sphingomyelin increases in cell membranes in response to aging and numerous pathological conditions. High dietary iron reduced linolenic acid in phosphatidyl-ethanolamine and phosphatidylcholine of both skeletal and cardiac muscle. This may have resulted from iron-caused ethane production from autoxidation of linolenic acid or other n-3 family fatty acids, an effect known to occur in the rat. Linoleic and arachidonic fatty acids appeared to be unaffected. Plasmalogens in muscle and heart phosphatidylethanolamine and phosphatidylcholine were increased by high iron intake. As these alk-1-enyl ethers protect cells from oxidation and radiation damage, their synthesis may have been increased in response to stress from excessive iron. The results indicate that a relatively high concentration of vitamin E may be required in calf milk replacer when excessive iron is present.

Animals↗

PubMed1988

Binding of selenium-75 to blood and liver cytosolic proteins in the preruminant calf.

Labeled selenite (75Se) administered to calves in milk replacer, containing .2 or 5 ppm Se, was rapidly absorbed with peak blood 75Se at 6 h. Gel filtration and dialysis treatment of plasma and erythrocyte hemolysates showed that initially 75Se was transported in blood as 75SeO3= or loosely bound to plasma and erythrocyte proteins. At high Se intake, albumin became a transport protein for some of the plasma 75Se, and proportionately more blood radioactivity was carried in the erythrocytes. At 72 h after dosing, most plasma 75Se was tightly bound to protein in glutathione peroxidase fraction with low peroxidase activity, possibly Se transport protein. At 72 h, distribution of 75Se in erythrocyte was 35 to 40% in glutathione peroxidase, 50% in hemoglobin, and 5% in a selenite plus selenopolypeptide fraction. Erythrocyte peroxidase activity was mostly in the glutathione peroxidase fraction (57%) and hemoglobin (38%). Molecular weight estimate for erythrocyte glutathione peroxidase was 84,200 daltons; about 90% of blood peroxidase activity was in erythrocytes. High Se intake had no marked effect on distribution of 75Se among liver cytosolic proteins. About 35% of 75Se was in glutathione peroxidase fraction, having most of the peroxidase activity, 25% in void volume, 11 to 18% in a selenite plus selenopolypeptide fraction, and small amounts in selenoproteins of about 12,000 and 50,000 daltons.

Animals↗

PubMed1988

Plasma lipoproteins in neonatal, preruminant, and weaned calf.

This study compared plasma lipoprotein fraction profiles and lipid composition in the calf at 3 d, 3 wk, and 12 wk (weaned). For all ages the major plasma lipoprotein fraction was high density lipoproteins (52 to 73%), followed by very high density lipoproteins (10 to 22%), low density lipoproteins (13 to 18%), and chylomicrons plus very low density lipoproteins (5 to 9%). Most plasma lipid was cholesterol esters (41 to 49%) and phosphatidylcholine (21 to 29%). Most cholesterol esters (66 to 81%) and phosphatidylcholine (68 to 80%) were in high density lipoproteins; free fatty acids (83 to 96%) and lysophosphatidylcholine (75 to 85%) in very high density lipoproteins; and triglycerides (93 to 98%) in the remaining lipoprotein fractions. Of the three ages studied, 3-d-old calves had comparatively low plasma total lipids, high density lipoproteins, cholesterol esters, phosphatidylcholine, and linoleic acid in all lipid classes; they had relatively high plasma very high density lipoproteins, triglycerides, free fatty acids, phosphatidylethanolamine, and 20:3 n-9 fatty acid (indicative of essential fatty acids deficiency). Lipoprotein classes and lipid composition were similar at wk 3 and 12. Comparison of fatty acid profiles for phosphatidylcholine with those for lysophosphatidylcholine and cholesterol esters indicated plasma lecithin-cholesterol acyltransferase was active in calves at all three ages studied.

Aging↗

PubMed1988

Factors affecting poor performance and scours in preruminant calves fed corn oil.

A 4-wk study with 12 3-d-old calves compared the effect of feeding tallow, corn oil, or corn oil plus aspirin on calf performance, feed utilization, incidence of scours, and composition of blood plasma lipids. Aspirin treatment was to inhibit a possible role of prostaglandins in promoting scours. Calves given both corn oil treatments had lower average daily gain, feed efficiency, and higher incidence of scours than those fed tallow. Unexpectedly, corn oil produced appreciably less scours in calves than encountered in previous studies. This appeared to be related to the fat dispersion method used here, which produced much smaller fat globules (less than 1 micron vs. 10 to 20 microns). Over-production of prostaglandins from corn oil was not a causative factor in scours development. Arachidonic acid and other linoleic acid prostaglandin precursors in blood plasma cholesteryl esters and phosphatidylcholine were reduced by dietary corn oil. Aspirin, a potent inhibitor of prostaglandin biosynthesis, was ineffective in reducing scours.

Animals↗

PubMed1987

Performance of calves fed combinations of whole milk and reconstituted skim milk powder.

A 52-d study with 24 3-d-old calves compared the effect of feeding whole milk (controls) or milk diluted 1:1 or 1:3 with reconstituted skim milk powder (10%, wt/wt) on calf performance to weaning at 38 d. Skim powder diets were supplemented with vitamins and trace minerals. Liquid diet was fed at 5% body weight twice daily for 24 d, then once daily for 14 d followed by abrupt weaning. Starter was provided for ad libitum intake from 14 to 52 d. For the first 13 d, controls had the greatest weight gains, but at 38 and 52 d, gains were similar for all groups. Three-quarters of the whole milk diet could be replaced with reconstituted skim milk powder (10% wt/wt) without any reduction in calf gain to weaning because starter intake increased 23%.

Animal Nutritional Physiological Phenomena↗

PubMed1987

Effect of excess iron in milk replacer on calf performance.

Milk replacers containing 100, 500, 1000, 2000, or 5000 ppm iron were fed to 3-d-old calves for 6 wk to estimate the lowest amount of dietary iron (added as ferrous sulfate) that would reduce calf performance. Calves tolerated all iron treatments except 5000 ppm. At this intake calves showed reduced weight gains, DM intake, feed efficiency, and digestibility of DM and protein. There were no other signs of iron toxicity and no gross abnormalities were found on postmortem examination. Percent of dietary iron in feces increased with higher dietary iron and ranged from 65 to 84%. Elevated iron intakes caused relatively small increases in iron concentration of blood plasma, bile, kidney, heart, and muscle but marked increased in spleen and liver iron, particularly in liver for the 2000 and 5000 ppm treatments. At 100 ppm iron intake, nonheme iron in liver, spleen, and kidney was composed of similar proportions of ferritin and hemosiderin, but at 5000 ppm iron intake, hemosiderin predominated in these tissues. Thus, the preruminant calf tolerated between 2000 and 5000 ppm iron in milk replacer. At toxic iron intake, calf performance and feed efficiency were reduced; there was a characteristic change to higher liver than spleen iron; and hemosiderin became the predominant iron storage compound in both tissues.

Animal Feed↗

PubMed1986

Fatty acid-binding protein in liver and small intestine of the preruminant calf.

Cytosol obtained from differential centrifugation of homogenates from liver and small intestine mucosa was incubated with 1-[14C] oleic acid or 1-[14C] palmitic acid and filtered through Sephadex G-75. Elution profiles for both tissues showed radioactivity in two main peaks, the first corresponding to binding of fatty acid to high molecular weight proteins and the second to a protein fraction with a molecular weight of approximately 12,000 daltons. The low molecular weight fraction had high fatty acid-binding activity, which was greater for oleic than palmitic acid. The findings demonstrate the presence of fatty acid-binding protein in liver and intestinal mucosa of the preruminant calf.

Animals↗

PubMed1986

Effect of lipids in milk replacers on calf performance and lipids in blood plasma, liver, and perirenal fat.

Various fats (20% of dry matter) were fed in milk replacer to calves, from 3 to 31 d of age, to compare their effect on calf performance, feed efficiency, and lipids in blood plasma, liver, and perirenal fat. Dietary fats tested were tallow (control), canola oil, canola soapstocks, corn oil, reclaimed restaurant cooking fat, and a high phospholipid waste product. Corn oil plus tallow (1:1) diet promoted scours and poor calf gains, but canola oil diet, despite a high content of unsaturated fatty acids, gave excellent calf performance and feed utilization and no scours. Canola soapstocks plus tallow (1:1) and restaurant waste cooking fat lowered gains by 25 and 15% and reduced diet intake. Calves effectively utilized high phospholipid (23%) in dietary lipids. Main lipid classes in blood plasma were cholesterol esters and phosphatidylcholine, and in liver phosphatidylethanolamine and phosphatidylcholine. Fatty acid composition of the major blood plasma and liver lipids, and of perirenal fat, tended to reflect dietary fatty acid concentrations.

Adipose Tissue↗

PubMed1986

Influence of low linoleic and linolenic acids in milk replacer on calf performance and lipids in blood plasma, heart, and liver.

In a 6-wk study with 3-d-old calves (n = 32), we compared effects of low or adequate essential fatty acids in milk replacers on calf performance, feed utilization, and fatty acids in blood plasma, heart, and liver lipids. Four dietary treatments were hydrogenated coconut oil, as low-essential fatty acid basal; basal plus linoleic acid; basal plus linoleic plus linolenic acids; tallow control. None of the calves fed low essential fatty acid diet developed any external deficiency signs seen in monogastric animals. Supplementation of basal diet with essential fatty acids had no influence on weight gains, feed efficiency, or digestibility of lipids, nitrogen, and dry matter. Effects of low essential fatty acid intake were decreased resistance of erythrocytes to lysis, and in tissue lipids, marked reduction of linoleic acid and elevation of trienoic acid, palmitoleic acid, and ratio of trienoic acid to arachidonic acid, all indicative of low essential fatty acid status. Essential fatty acid intake in milk replacer may be more important than indicated here for longer term vealer calves, and where stresses, such as infectious diseases and high environmental temperature, are present.

Animals↗

PubMed1986

Tolerance of the preruminant calf for selenium in milk replacer.

Calves were fed skim milk powder-based milk replacer containing either .2, 1, 3, 5, or 10 ppm selenium (added as sodium selenate) in the dry matter from 3 to 45 d of age to estimate the lowest amount of dietary selenium that would reduce calf performance and feed utilization. Only at the highest selenium (10 ppm) did calves show reduced average daily gain and feed efficiency and lower blood packed cell volume. Apparent digestibility of dry matter, nitrogen, and lipid, and plasma creatine phosphokinase activity were not affected by any of the selenium intakes. In general, selenium in blood, bile, duodenal mucosa, liver, kidney, and muscle reflected selenium intakes with liver and kidney reaching the highest selenium concentrations. Postmortem examinations of calves revealed no gross abnormalities for any of the selenium treatments. The preruminant calf is very tolerant of high inorganic selenium concentrations in skim milk powder-based milk replacer.

Animal Feed↗

PubMed1985

Influence of triglycerides and free fatty acids in milk replacers on calf performance, blood plasma, and adipose lipids.

In a 4-wk study of 48 3-day-old calves we compared effects of feeding various fats or their free fatty acids in skim milk-powder based milk replacer, on calf performance, feed utilization, and blood plasma and adipose lipids. When fat was fed, calf performance and feed utilization were equivalent for tallow and coconut oil diets but markedly poorer for corn oil. Complete replacement (tallow) or one-half replacement (coconut and corn oils) of the fats with their free fatty acids reduced calf gains and feed efficiency. Tallow free fatty acids gave lower digestibilities of palmitic and stearic acid and reduced calcium absorption. Free fatty acids from both coconut and corn oils reduced diet palatability and intake; those from tallow and coconut oil markedly interfered (in vitro) with rennet clotting of milk replacers. The main lipid classes in blood plasma for all treatments were cholesteryl esters and phosphatidylcholine. High concentrations (56 to 87%) of linoleic acid occurred in cholesteryl esters for all diets despite low concentrations of linoleic acid in the tallow and coconut oil diets.

Adipose Tissue↗

PubMed1981

Digestion of fat in calves fed milk replacers prepared by homogenization of low-pressure dispersion.

High-fat (40% of dry matter) milk replacers were fed to calves from 3 to 14 days of age to determine the effect of fat dispersion method on abomasal retention of dietary fat and crude protein and on digestion of fat in upper parts of the gastrointestinal tract. Relative to homogenization, low pressure dispersion of fat into milk replacer resulted in a) much larger rennet clots in the abomasum, b) increased abomasal retention of dietary triglycerides and crude protein, and c) increased triglyceride hydrolysis in the abomasum, duodenum, and upper jejunum at 4 h after feeding. When high-fat diet was fed to postnatal calves, formation of large firm clots was beneficial for promoting a slower release of fat and protein into the duodenum, and digestion of fat was improved in the gastrointestinal tract. Pregastric esterase hydrolysis of dietary triglycerides (tallow, coconut oil) in the abomasum resulted in preferential release of capric, lauric, and myristic fatty acids and a proportionately low release of palmitic and stearic acids.

Abomasum↗

PubMed1977

Influences of barley and oat silages for beef cows on occurrence of myopathy in their calves.

Sixteen pregnant Shorthorn cows were winter-fed either oat or barley silage, both of which were low in selenium (less than .1 ppm). Two months before calving, as well as at calving and a month later, four cows on each diet were given intramuscularly a preparation containing 1360 IU of vitamin E and 30 mg selenium as sodium selenite. Barley silage lipids contained higher linoleic (33.2 versus 22.3%) and palmitic acids (32.3 versus 23.1%), and lower oleic (6.3 versus 22.1%) and linolenic acids (20.9 versus 30.9%) than oat silage. Three calves born from the untreated dams on barley silage died from nutritional muscular dystrophy by 50 days of age whereas none of the calves either from the untreated cows on oat silage or from any of the selenium/vitamin E treated cows. Milk from untreated cows fed barley silage contained a higher proportion of linoleic acid than that from treated cows or from those on oat silage. The incidence of nutritional muscular dystrophy was associated closely with ingestion by the calves of an increased amount of dietary dienoic acid. It appears an advantage to include oat silage in winter feeding programs for beef cows to reduce the risk of development of nutritional muscular dystrophy in the offspring.

Animal Feed↗

PubMed1974