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Tissue protein synthesis in lactating and dry goats
V E Baracos1, J Brun-Bellut, M Marie
1Ecole Nationale Supérieure d'Agronomie et des Industries Alimentaires, Institut Nationale Polytechnique de Lorraine, Vandoeuvre, France.
The British Journal of Nutrition
|November 1, 1991
Summary
Lactating goats exhibit increased whole-body protein synthesis, particularly in mammary and visceral organs, to support milk production. This occurs at the expense of muscle and skin protein synthesis, utilizing body reserves.
Area of Science:
- Animal Science
- Nutritional Biochemistry
- Metabolic Physiology
Background:
- Lactation significantly alters nutrient partitioning and protein metabolism in dairy animals.
- Understanding tissue-specific protein synthesis is crucial for optimizing animal nutrition and productivity.
Purpose of the Study:
- To quantify the impact of lactation on whole-body and tissue-specific protein synthesis rates in dairy goats.
- To investigate the metabolic adaptations supporting milk production.
Main Methods:
- Intravenous infusion of L-[3H]phenylalanine (Phe) for 8 hours in dry and lactating goats.
- Measurement of nitrogen balance.
- Estimation of fractional protein synthesis rates (Ks) using plasma- (Ksp) and tissue- (Ksh) specific radioactivities.
Main Results:
- Lactating goats showed a 50% greater whole-body Phe flux and positive nitrogen balance.
- Increased Ksp in mammary gland, duodenum, and diaphragm of lactating goats.
- Decreased Ks and absolute protein synthesis rates in hind-limb skin and skeletal muscle of lactating goats.
Conclusions:
- Lactation induces significant shifts in protein metabolism, prioritizing mammary and visceral organ synthesis.
- Reduced muscle and skin protein synthesis contribute to mobilizing body reserves for milk production.
- These findings highlight the metabolic cost of lactation and potential nutritional strategies.