| Autor: |
R.M Kirkland, T. Yan, R.E. Agnew, F.J. Gordon |
| Rok vydání: |
2002 |
| Předmět: |
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| Zdroj: |
Livestock Production Science. 73:131-138 |
| ISSN: |
0301-6226 |
| DOI: |
10.1016/s0301-6226(01)00259-7 |
| Popis: |
The objective of the experiment was to examine a novel approach of determining the efficiency of utilisation of body tissue for milk production (krl) on a within cow basis and using a limited number of animals treated similarly. Six lactating Holstein–Friesian dairy cows (mean milk yield 19.6 kg/day; days in milk 178) were subjected to measurements of energy balance using indirect calorimeters. Cows remained in the calorimeters for a total of 9 days during which two levels of metabolisable energy intake (MEI) were offered (either sufficient to meet requirements for zero tissue balance, days 1–3; or, this allowance reduced by 70 MJ/day, days 4–9). The mean values across days 1–3 and days 6–9 were used in two subsequent analyses. In method (1), a multiple regression relationship was developed to derive metabolisable energy requirements for maintenance (MEm) and efficiency of use of ME for milk production (kl). In method (2), a logistic regression relationship between heat production and MEI was developed. The results derived from methods (1) and (2) were used to determine the quantity of milk energy produced from body tissue and subsequently krl. The latter was determined as 0.791 (S.D. 0.0685) and 0.825 (S.D. 0.0537) using the two methods. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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