Semester

Fall

Date of Graduation

1998

Document Type

Dissertation

Degree Type

PhD

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

H. Klandorf.

Abstract

The factors which influence the age-related decline in production performance and increases in meat toughness in broiler breeder hens are poorly understood. We have hypothesized that the elevated plasma concentration of glucose contributes to the nonenzymatic attachment of glucose to proteins, and generates glycoxidation crosslinks in tissues which can ultimately impair function, is responsible for loss of production. One such crosslink, pentosidine, is an established indicator of both glycative and oxidative tissue damage in mammals. Specifically, the role of diet restriction (DR) and a nucleophilic hydrazine compound, aminoguanidine (AG), a crosslinking inhibitor, were examined on tissue crosslinking with the view towards both extending the production period and improving carcass quality of broiler breeder hens. Additionally, isolation of pentosidine from skin and tendons of hens and their relationship with tendon breaking strength (TBS), time (TBT) and meat tenderness (SF) were carried out. Chicks were randomly divided into four dietary groups from eight to 125 wks after hatch: ad libitum (AL); diet restricted (DR, fed 60% of ad libitum ); AL and DR groups supplemented with 400 ppm AG (1.35 mg/kg BW/day) each (AL+ AG and DR+AG respectively).;The results showed that pentosidine was present in the skin (Ps ) and tendon (Pt) of the broiler breeder hens, and that there was an age-related, linear increase in its concentration (p<0.001, r2=0.94) for skin and (p<0.0001; r2=0.79) for tendon in AL-fed hens. DR and supplementation of AG with AL-fed hens (AL+AG) retarded Ps (p<0.001; p<0.001) and Pt (p<0.001; p<0.01) respectively as compared to AL-fed hens. Concurrently, there was also an age-related parallel increase in TBS ( p<0.0001; r2=0.56), in TBT ( p<0.0001; r2=0.67), and in shear force (SF) (p<0.0001; r2=0.95) in AL-fed hens. Similarly DR significantly retarded the overall TBS ( p<0.01) TBT (p<0.02), and SF (p<0.0001) values as compared to AL-fed hens over the period of this study. Supplementation of AL-fed hens with AG (AL+AG group) significantly retarded the concentration of Pt, Ps and SF values and was similar to those of the t s DR group. Although, supplementation of DR with AG (DR+AG) retarded the rate of accumulation of Ps (p<0.001) over the laying cycle, the reduction in Ps did not significantly affect s s the mean production. It is therefore concluded that the rate of P s and Pt accumulation and the s t age-related increase in meat toughness can be retarded by either DR or AG. Ps can also be used s as a predicator of age-related changes in meat. The same approach has the potential to be initiated in other animal production systems. Because of the linear, age-related increase in the concentrations of tissue pentosidine, it can be used as biomarker for the study of aging.

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