Body protein losses estimated by nitrogen balance and potassium-40 counting
Body protein losses estimated from N balance were compared with those estimated by 40K counting. Six nonlactating dairy cows were fed an adequate N diet for 7 wk, a low N diet for 9 wk, and a replete N diet for 3 wk. The low N diet contained high cell wall grass hay plus ground corn, starch, and molasses. Soybean meal was added to the low N diet to increase N in the adequate N and replete N diets. Intake was measured daily. Digestibilities, N balance, and body composition (estimated by 40K counting) were determined during each dietary regimen. During low N treatment, hay dry matter intake declined 2 kg/d, and supplement increased about .5 kg/d. Dry matter digestibility was not altered by N treatment. Protein and acid detergent fiber digestibilities decreased from 40 and 36% during adequate N to 20 and 2%, respectively, during low N. Fecal and urinary N also declined when cows were fed the low N diet. By the end of repletion, total intake, fiber, and protein digestibilities as well as N partition were similar to or exceeded those during adequate N intake. Body protein (N) loss was estimated by N balance to be about 3 kg compared with 8 kg by 40K counting. Body fat losses (32 kg) were large because of low energy digestibility and intake. Seven kilograms of body fat were regained during repletion, but there was no change in body protein.
- Research Organization:
- Univ. of Missouri-Columbia
- OSTI ID:
- 5006327
- Journal Information:
- J. Dairy Sci.; (United States), Vol. 7
- Country of Publication:
- United States
- Language:
- English
Similar Records
Efficiency of energy utilization: effects of diet composition on body composition and mammary neoplasia
Body composition of lactating and dry Holstein cows estimated by deuterium dilution
Related Subjects
PROTEINS
BODY COMPOSITION
CATTLE
DIET
LOSSES
MATERIAL BALANCE
NITROGEN
POTASSIUM 40
TRACER TECHNIQUES
WHOLE-BODY COUNTING
ALKALI METAL ISOTOPES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
COUNTING TECHNIQUES
DOMESTIC ANIMALS
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAMMALS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
POTASSIUM ISOTOPES
RADIOISOTOPES
RUMINANTS
VERTEBRATES
YEARS LIVING RADIOISOTOPES
553001* - Agriculture & Food Technology- Tracer Techniques- (-1987)