Feed Conversion Efficiency, More Money and Less Manure?
By Alejandro R. Castillo
UCCE Merced County
California dairy producers face the challenges of complying with environmental regulations while maintaining profitability. Managing feed conversion efficiency (FCE) may help to overcome both challenges. The FCE is defined as the proportion of feed that is converted into milk, and is normally expressed in lbs. of milk/ lb. 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/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 3 to 5 diets or total mixed rations (TMR) according to milk yield per cow, and/or (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 2, 3, and 4 TMR 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 vs. 1.38 lb. milk/lb. dry matter intake in 2003 and 2008 respectively.
Formulating diets without the appropriate feed analysis and/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 lb. milk/lb. dry matter intake the NUE is approximately 30%, 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 and/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 and/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 lb. milk/ lb. dry matter intake
- 30% NUE for lactating dairy cows.
Figure 1. Proportion of dairies feeding different diets or Total Mixed Rations (TMR) for lactating dairy animals in Merced County.
Figure 2. Relationship among Feed Conversion Efficiency (FCE) and Nitrogen Utilization Efficiency (NUE) in Merced County dairy farms.
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