Dairy producers face the challenges of complying with environmental regulations while maintaining profitability.
Managing feed conversion efficiency (FCE) may help to overcome both challenges.
FCE is defined as the proportion of feed that is converted into milk, and is normally expressed in pounds of milk per pound of dry matter intake. When FCE is improved, cows produce more milk (or gross income) and less manure with the same amount of feed. Feeding according to animal requirements maximizes milk yield per cow and the efficiency of nutrient utilization. When nutrients are fed in excess, both manure production and the energy cost of excretion increases, affecting energy balance and milk yield per cow.
Several factors are negatively associated with FCE, including: days in milk, proportion of first- lactation cows, animal comfort and unbalanced diets. All these factors should be planned and controlled to reduce or minimize any possible negative impact on FCE. Some management practices that minimize unbalanced diets and maximize FCE are:
1. managing three to five diets or total mixed rations (TMR) according to milk yield per cow
2. balancing diets based on the complete nutrient composition of each feed ingredient, including macro and trace minerals
Results from two surveys carried out in Merced County in 2003 and 2008 indicated an improvement in group feeding management practices. The proportion of dairies feeding two, three and four TMRs increased in 2008 relative to the information from the 2003 survey (Figure 1*). However, the estimates of FCE were similar in both surveys: 1.40 versus 1.38 pounds milk per pounds dry matter intake in 2003 and 2008, respectively.
Formulating diets without the appropriate feed analysis or not following recommendations may explain the lack of response of FCE in 2008. In both surveys, the nitrogen utilization efficiency (NUE) was positively correlated with FCE, indicating that FCE increased as NUE increased, and vice-versa (Figure 2*). Based on these results, when FCE is 1.65 pounds milk per pounds dry matter intake the NUE is approximately 30 percent, which is the suggested benchmark for nitrogen utilization. Balancing dietary nitrogen (protein) may improve FCE, but balancing other nutrients and minerals may also help to improve FCE or mitigate possible environmental impacts.
Grouping animals according to nutrient requirements and balancing dietary ingredients based on complete chemical analysis should be considered to maximize FCE and minimize manure and nutrient excretion. But, improving feeding strategies by grouping cows is not a viable option for all dairy operations, especially those with a low number of cows or with infrastructure limitations. In these cases, dairy farmers and nutritionists should review all the possibilities to control and improve FCE, particularly complete feed ingredient chemical analysis.
The suggested benchmark challenges are:
• FCE no less than 1.6 pounds milk per pounds dry matter intake
• 30 percent NUE for lactating dairy cows PD
—Excerpts from University of California Merced County Dairy Newsletter, January 2009
*References and figures omitted but are available upon request to editor@progressivedairy.com
Alejandro Castillo
Merced County Extension
University of California
arcastillo@ucdavis.edu
