| Autor: |
W.P. Flatt, H.F. Tyrell, P.W. Moe |
| Rok vydání: |
1972 |
| Předmět: |
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| Zdroj: |
Journal of Dairy Science. 55:945-958 |
| ISSN: |
0022-0302 |
| DOI: |
10.3168/jds.s0022-0302(72)85601-7 |
| Popis: |
Results of 543 energy balance trials with lactating cows were summarized to partition the energy required by lactating cows into maintenance and production components and to determine the influence of energy source on the efficiency with which dietary energy is used for milk production. The total energy requirement for lactating cows was expressed in net energy for milk production (NE milk ). The amount of energy required for maintenance of a nonpregnant, lactating cow in body energy equilibrium and ingesting a diet of optimum protein content under conditions of limited physical activity was 73kcal NE milk per kg .75 body weight. The amount of net energy required for milk production was .74 Mcal NE milk /kg 4% fat-corrected milk. The NE milk , of individual diets was related to the concentration of digestible energy (DE) in the diet by the equation: NE milk (Mcal/kg DM) = .68 DE (Mcal/kg DM) — .36. Variation in energetic efficiency of metabolizable energy for milk production was much less than for digestible energy. Metabolizability of diets was not a constant proportion of digestible energy but was related to concentration of DE and to feed intake. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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