Factors affecting energy and nitrogen efficiency of dairy cows: A meta-analysis
- 1 November 2013
- journal article
- research article
- Published by American Dairy Science Association in Journal of Dairy Science
- Vol. 96 (11), 7245-7259
- https://doi.org/10.3168/jds.2013-6977
Abstract
A meta-analysis was performed to explore the correlation between energy and nitrogen efficiency of dairy cows, and to study nutritional and animal factors that influence these efficiencies, as well as their relationship. Treatment mean values were extracted from 68 peer-reviewed studies, including 306 feeding trials. The main criterion for inclusion of a study in the meta-analysis was that it reported, or permitted calculation of, energy efficiency (Eeff; energy in milk/digestible energy intake) and nitrogen efficiency (Neff; nitrogen in milk/digestible nitrogen intake) at the digestible level (digestible energy or digestible protein). The effect of nutritional and animal variables, including neutral detergent fiber, acid detergent fiber (ADF), digestible energy, digestible protein, proportion of concentrate (PCO), dry matter intake, milk yield, days in milk, and body weight, on Eeff, Neff, and the Neff:Eeff ratio was analyzed using mixed models. The interstudy correlation between Eeff and Neff was 0.62, whereas the intrastudy correlation was 0.30. The higher interstudy correlation was partly due to milk yield and dry matter intake being present in both Eeff and Neff. We, therefore, also explored the Neff:Eeff ratio. Energy efficiency was negatively associated with ADF and PCO, whereas Neff was negatively associated with ADF and digestible energy. The Neff:Eeff ratio was affected by ADF and PCO only. In conclusion, the results indicate a possibility to maximize feed efficiency in terms of both energy and nitrogen at the same time. In other words, an improvement in Eeff would also mean an improvement in Neff. The current study also shows that these types of transverse data are not sufficient to study the effect of animal factors, such as days in milk, on feed efficiency. Longitudinal measurements per animal would probably be more appropriate.Keywords
Funding Information
- European Commission, Framework 7
This publication has 100 references indexed in Scilit:
- TRIENNIAL LACTATION SYMPOSIUM: Opportunities for improving milk production efficiency in dairy cattle1,2Journal of Animal Science, 2012
- Digestion, milk production and milk fatty acid profile of dairy cows fed flax hulls and infused with flax oil in the abomasumJournal of Dairy Research, 2011
- Effect of replacing calcium salts of palm oil distillate with incremental amounts of conventional or high oleic acid milled rapeseed on milk fatty acid composition in cows fed maize silage-based dietsAnimal, 2011
- Developing breeding schemes to assist mitigation of greenhouse gas emissionsAnimal, 2010
- Efficiency of energy utilisation and voluntary feed intake in ruminantsAnimal, 2010
- Relating life cycle assessment indicators to gross value added for Dutch dairy farmsEcological Economics, 2009
- Molecular basis for residual feed intake in beef cattle1Journal of Animal Science, 2009
- Selection for Increased Production and the Welfare of Dairy Cows: Are New Breeding Goals Needed?AMBIO, 2005
- Metabolic differences in Angus steers divergently selected for residual feed intakeAustralian Journal of Experimental Agriculture, 2004
- Effects of energy and protein supplementation on microbial-N synthesis and allantoin excretion in sheep fed guinea grassAnimal Feed Science and Technology, 2000