Doctoral Dissertations

Date of Award

8-1974

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

H.V. Shirley

Committee Members

R.L. Murphee, Sam L. Hansard, P.B. Coulson

Abstract

Experiments were conducted to compare the lipogenic and lipotrophic properties of selected treatments in laying hens.

"Lipogenic" factors studied were: high fat, rancid fat, rancid feed, orotic acid, aflatoxin, carbon tetrachloride and ethionine. "Lipotrophic" factors included: vitamins E and C, choline, santoquin, biotin, linoleic acid and selenium. With a few exceptions, each "lipotrophic" factor was tested in combination with each "lipogenic" factor.

Two-hundred and nineteen Leghorn type pullets, 30 weeks of age, were used in seven experiments. All hens were housed in individual laying cages and received standard management procedures,

Physiological parameters measured included the following: percent liver fat, liver weight, liver color, liver texture, liver haemorrhages, abdominal fat, comb condition, blood prothrombin time, sodium bromosulphthalein (BSP) clearance, egg production, egg weight, egg specific gravity and bone strength.

When compared with the standard laying ration, the rancid fat ration without additions significantly increased the percent liver fat, liver weight and the incidence of liver haemorrhages. The rancid feed ration also resulted in an increased in liver fat. BSP clearance rate was significantly reduced by the ethionine treatment. Egg weight was reduced by the high fat ration and egg specific gravity was reduced by the carbon tetrachloride treatment. Other differences were non-significant.

The effects of the "lipotropic" factors on most of the traits were highly variable and were influenced by the type of "lipogenic" treatment with which they were combined.

Choline exerted a lipogenic effect when fed in combination with a high fat ration - the percent of liver fat was increased. Choline reduced liver fat in the rancid feed and rancid fat treatments. The percent liver fat was decreased by vitamins C and E, santoquin and biotin in the rancid feed treatment and by choline in the rancid fat treatment.

Liver color was significantly influenced by "lipotropic" factors in the ethionine treatment only. Choline, santoquin and biotin resulted in livers with a greater degree of yellow color.

Choline in the ethionine treatment resulted in livers that were less fragile, while linolic acid combination with ethionine increased the fragility of the liver.

Choline reduced the incidence of haemorrhages in the rancid fat treatment. Liver haemorrhages were increased by dietary biotin and linoleic acid in the high fat treatment and santoquin in the rancid feed treatment.

The degree of abdominal fatness was reduced only by the feeding of biotin in the rancid feed treatment.

Prothrombin time was significantly increased by a wide variety of the "lipotropic" factors. Choline, santoquin, biotin, linoleic acid, vitamin C and vitamin E in the rancid feed treatment increased prothrombin time, as well as linoleic acid in the high fat treatment. Biotin reduced the prothrombin time in the ethionine treatment.

Sodium bromosulphthalein clearance rate was lowered by choline but was raised by linoleic acid In the ethionine treatment.

Bone strength was reduced by choline, santoquin and biotin In rancid fat treatment but was Increased by vitamin C In the rancid feed treatment.

These results suggest that rancidity In laying rations Is a most likely cause of abnormally high fat deposition In the livers of hens and of other traits commonly associated with the "fatty liver syndrome". Of the substances tested In these experiments, the most effective were those that possess anti-oxidative properties or those subject to destruction by developing feed rancidity.

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