Lothar Panicke

Heritability of metabolic response to the intravenous glucose tolerance test in German Holstein Friesian bulls

Selection for improved health and welfare in farm animals is of increasing interest worldwide. Peripartum energy balance is a key factor for pathogenesis of diseases in dairy cows. The intravenous glucose tolerance test (ivGTT) can be used to study the metabolic response to a glucose stimulus. The aim of this study was to estimate heritability of ivGTT traits in German Holstein bulls. A total of 541 Holstein bulls aged 7 to 17 mo from 2 breeding stations were subjected to the ivGTT. Serum glucose concentrations were measured at 0, 7, 14, 21, 28, 35, 42, 49, 56, and 63 min relative to glucose infusion. The maximum increase in blood glucose concentration, glucose area equivalent, and blood glucose half-life period were calculated. Heritabilities were estimated using a univariate animal model including station-year-season and age as fixed effects, and animal additive genetic and residual as random effects. The estimated heritabilities were 0.19 for fasting glucose concentration, 0.43 for glucose area equivalent, 0.40 for glucose half-life period, 0.14 for the peak glucose concentration, and 0.12 for the maximum increase of blood glucose concentration. Correlations between ivGTT traits and breeding values for milk yield and composition were not found. The results indicate that heritability for response to glucose is high, which warrants further investigation of this trait for genetic improvement of metabolic disorders. Research is necessary to determine the target levels of ivGTT traits and potential associations between ivGTT traits in breeding bulls and periparturient diseases in their offspring.

Proteolytische Aktivitäten der lysosomalen Enzyme bei Milchrindern* n 3. Mitteilung: Beziehungen der Energie- und Eiweißversorgung zur lysosomalen Enzymaktivität im Blutplasma beim Milchrind

Abstract. Title of the paper: Relationship between lysosomal blood activity and milk content» of urea and protein in different phases of milk production in dairy cows Relationship of lysosomal enzyme activities in blood and supply of energy and protein in dairy cattle were investigated. Closed correlation coefficients were calculated for lysosomal enzyme activity and content of protein and urea in milk. Especially a high or a low content of protein in the food ration affects the lysosomal enzyme activities considerably. A different lysosomal response to equal food supply was gained after deviding the cow stock into different groups regarding performance at a different lactation status. Growth, breed, age, capacity of food intake and milk performance might be influencing factors.