Heifers on the study resting at the SDSU Dairy Research and Training facility.
Written collaboratively by Angie Manthey and Jill L. Anderson.
In late years, limit-fed nutrient dense diets at a set rate or proportion of body weight of growing dairy heifers has been proved to improve digestibility of nutrients and feed efficiency, while maintaining growth performance (Zanton and Heinrichs, 2008). Additionally, using dried distillers grains with solubles (DDGS) as part of limit-fed diets improved digestibility of crude protein and fiber compared to a corn and soybean product based diet (Anderson et al., 2015). Also feeding increasing proportions of the diet as DDGS in limit-fed rations can maintain growth performance, increase gain:feed, and improve digestibility (Manthey et al., 2016).
Due to different housing facilities and management strategies, limit-feeding total rations (both forage and as well concentrate mix are limit-fed) may not always be practical. For example, when limit-feeding a complete ration, it is very important that all heifers have equal access to the feed for extended periods of time. Considering some of these issues, we questioned what would happen if just the DDGS was limit-fed and then heifers were allowed free-choice or ad libitum access to hay? This is similar to the common feeding strategy where a concentrate mix is fed and then heifers are fed bales of hay or other fibrous forages free choice. Additionally, the fat content of DDGS may improve the feed efficiency maintaining the growth performance.
Photo 1. Individual Calan gate feeding boxes for heifers at the SDSU Dairy Research and Training Facility.
To answer these questions a study was conducted by the South Dakota State University Dairy and Food Science Department. Twenty-four heifers (18 Holstein and 6 Brown Swiss) that were approximately 7 months of age were used in a feeding experiment lasting 16 weeks.
Treatments were: 1) corn and soybean product concentrate mix (CON), and 2) DDGS based concentrate mix (DDG). Both concentrate mixes were limit-fed at 0.8% of BW (DM basis) and brome grass hay was fed free-choice or ad libitum (Table 1). The DDGS used for the experiment contained 10.2% fat (ether extract) and 30.6% crude protein on a dry matter basis. Heifers were fed individually (Photo 1) and intakes were recorded daily. Frame growth and body weights were measured every two weeks. During the study rumen fluid was collected via esophageal tubing every 4 weeks and in week 16 fecal samples were taken to determine total tract nutrient digestibility.
Table 1. Ingredient composition of treatment diets
|Ingredient, % of DM||CON||DDG|
|Brome grass hay (Predicted % of diet)||68.5||68.5|
|Expellers Soybean Meal||6.27||0.0|
|Vitamin and mineral premix**||0.75||0.75|
* Both treatment diets were formulated with NRC (2001) to contain 13.4% CP (% of DM), 7.4% RDP, 6.0% RUP, ME of 2.35 Mcal/kg of DM, and NEg of 0.87 Mcal/kg of DM.
At the start of the experiment it was speculated that heifers on the DDG treatment may consume slightly less due to the difference in satiety signals related to fat consumption and have better feed efficiency. However, overall dry matter intakes (Table 2) were similar between treatments, as were crude protein intakes. Neutral detergent fiber intakes, tended to be greater for heifers on the DDG treatment compare to the CON. This was because of the non-forage fiber content in the DDGS. Starch intake was greater and fat (ether extract) intake was less for the CON fed heifers versus the DDG fed heifers.
Table 2. Mean nutrient intakes amounts for heifers limit-fed a control (CON) or distillers dried grains with solubles (DDG) concentrate mix with ad libitum grass hay.
|Nutrient Intake, kg/d1||CON||DDG||SEM||Trt||wk||Trt × wk|
|Neutral Detergent Fiber||3.62||4.15||0.199||0.07||<0.01||0.47|
|Acid Detergent Fiber||2.04||2.21||0.114||0.33||<0.01||0.59|
1. Reminder: there are 2.2 lbs in a kg.
Growth performance results (Table 3) indicated that there were no differences in body weight (BW), average daily gains (ADG), or gain:feed between treatments. Frame measurements (not all shown) and body condition scores (BCS) increased over time as heifers grew, but were also similar between treatments.
Table 3. Growth performance for heifers limit-fed a control (CON) or distillers dried grains with solubles (DDG) concentrate mix with ad libitum grass hay.
|Item1||CON||DDG||SEM3||Trt||wk||Trt × wk|
|Age, initial, day||218.7||218.4||1.84||0.87||-||-|
|Body weight, kg|
|Dry matter intake, kg/d|
|Dry matter intake, % Body Weight|
|Withers height, cm||119.2||119.2||0.39||0.97||<0.01||0.28|
|1. Reminder: there are 2.2 lbs in a kg.
2. Significant of effects of treatment (Trt), week (wk), and treatment × week (Trt × wk).
3. SEM = Standard error of the mean
4. BCS = Body condition score; 1 = emaciated to 5 = obese
Rumen fluid analysis (Figure 1) showed that the DDG diet slightly shifted rumen fermentation. The proportion of propionate and butyrate increased in the DDG diet, while acetate proportion of total volatile fatty acids (VFA) decreased. This shift is likely the result of the differences in starch concentration between the concentrate mixes. These results suggest that heifers fed the DDG diet had more efficient rumen fermentation because there is less methane and carbon dioxide production when fermentation is shifted towards propionate compared to acetate. However, these small shifts in rumen fermentation were not enough to change growth performance. Also, there were no statistical differences in total tract digestibility of dry matter (DM), organic matter (OM), crude protein (CP), or neutral detergent fiber (NDF) between the two treatments (Figure 2).
Figure 1. Rumen Fermentation
Figure 2. Total Tract Digestibility*
* DM=Dry matter, OM=organic matter, CP=Crude Protein, NDF=Neutral Detergent Fiber
In conclusion, growth performance of the heifers was maintained when fed DDGS with ad libitum or free-choice hay compared to being fed a control concentrate mix with ad libitum hay. Although, feeding a DDG concentrate mix compared to a CON concentrate mix with ad libitum hay did not increase feed efficiency as originally hypothesized. This study demonstrated that producers can limit-feed a DDGS based concentrate mix with ad libitum grass hay and maintain heifer frame growth, ADG, and nutrient utilization compared to a corn and soybean product based concentrate mix.
Funding for this research was provided by the South Dakota Agricultural Experiment Station.
- Anderson, J. L., K. F. Kalscheur, A. D. Garcia, and D. J. Schingoethe. 2015. Feeding fat from distillers dried grains with solubles to dairy heifers: I. Effects on growth performance and total-tract digestibility of nutrients. J. Dairy Sci. 98:5699-5708.
- Manthey, A. K., J. L. Anderson, and G. A. Perry. 2016. Feeding distillers dried grains in replacement of forage in limit-fed dairy heifer rations: Effects on growth performance, rumen fermentation, and total-tract digestibility of nutrients. J. Dairy Sci. 99:7206–7215
- National Research Council. 2001. Nutrient Requirements of Dairy cattle. 7th Rev. Ed. Natl. Acad. Press, Washington, DC.
- Zanton, G. I., and A. J. Heinrichs. 2008. Rumen digestion and nutritional efficiency of dairy heifers limit-fed a high forage ration to four levels of dry matter intake. J. Dairy Sci. 91:3579-3588.