How efficient are dairy cows today?
In this country, we care about efficiency in almost every aspect of life. Stephen Covey in his book Seven Habits of Highly Effective People wrote: think effectiveness with people and efficiency with things, you can be efficient with things but not with people. How about animals? Well, the dairy industry cares a lot about efficiency in cows. Dr. Michael VandeHaar, professor at Michigan State University, is an expert in dairy efficiency, and below are some of his research summary.
Feed efficiency, or the efficiency of converting feed to milk (Figure 1), has a major influence on farm profitability and environmental stewardship in the dairy industry. Dairy feed efficiency in North America has doubled in the past 50 years (Figure 2), largely because of selecting, feeding, and managing cows for increased productivity. Increasing productivity results in a greater percentage of total feed intake being used for milk instead of cow maintenance (Figure 3). High producing dairy cows in the US currently partition 3 times more feed energy toward milk than toward maintenance.
Figure 1: The basics of feed efficiency. Courtesy of Dr. Michael VandeHaar.
Figure 2: Dairy cows today have much higher productivity and efficiency. Courtesy of Dr. Michael VandeHaar.
Figure 3: As cows eat more and produce more, a smaller percent of the feed is used for maintenance and a greater percent is converted to production. However, the incremental advantage in efficiency diminishes. Courtesy of Dr. Michael VandeHaar.
A recent publication showed that (Table 1) net energy requirement for maintenance and the efficiency of utilizing dietary energy for milk production and tissue gain increased in the more recent decades. The increase in maintenance requirements in modern milk production systems is consistent with the literature that describes increased fasting heat production in cows of higher genetic merit. The increase in utilization of dietary energy for milk production and tissue gain was partially attributed to the changes in dietary composition.
Table 1: Cows have increased metabolic rate and productive efficiency over the years. Data based on 1038 complete energy balance records from 284 Holstein cows in 40 studies conducted from 1963 to 1995 at the Beltsville USDA Energy Metabolism Unit. By Moraes et al., 2015. Multivariate and univariate analysis of energy balance data form lactating dairy cows. J. Dairy Sci. 98:4012-4029. Courtesy of Dr. Michael VandeHaar.
Although the efficiency of feed use by dairy cows seems to be low, 20-25% for energy and 20-30% for protein, we should bear in mind that cows eat many feeds that are not consumable to humans (Figure 4), such as cottonseeds, soyhulls, and distillers grains. These by-product feeds are generally less digestible than grains and may limit the ability of cows to produce the highest levels of milk. As competition for food grains increases, the ability of cows to utilize non-human-consumable foods into milk will become more important.
Figure 4: Cows are able to unitize many feeds that are not consumable by humans.
According to Dr. VandeHaar, we are not likely to continue to make major advances in feed efficiency simply by increasing milk per cow, but we can get more milk from each unit of feed. Management strategies to feed cows according to lactation stage will enhance feed efficiency. Genomic technologies likely will enable selection of more efficient cows, and we should breed for production, health, and fertility.
