BROOKINGS -- South Dakota State University dairy science Ph.D student Sanjeewa Ranathunga was recognized at the annual meeting of the Midwest American Dairy Science Association meetings with the Young Dairy Scholars Award.
Ranathunga is in the final stages of his Ph.D. program in dairy cattle nutrition at South Dakota State University, under the guidance of Kenneth Kalscheur, associate professor in dairy science.
During his time at SDSU, Ranathunga has conducted valuable research looking at dried distillers grains with solubles (DDGS) and their impact on dairy cattle diets.
Effective replacement for corn starch
Ranathunga began his master's program at SDSU in dairy cattle nutrition under Kalscheur after completing an M.S. in biochemistry at Pukyong National University in Busan, South Korea.
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His master's research demonstrated that the non-forage fiber provided from DDGS and soyhulls can effectively replace starch provided by corn in dairy cow diets without negatively affecting the performance of dairy cows.
This research revealed that DDGS can be used as an effective energy source to replace high-priced corn and can decrease the feed cost of the diet. According to income over feed cost analysis, an economic advantage if $1.42 per cow per day was observed in this study when feeding the 21 percent DDGS diet, compared with 0 percent DDGS diet.
Better understanding how DDGS is digested
Sanjeewa's Ph.D. dissertation research is to investigate carbohydrate digestion of DDGS in the rumen and total tract of the lactating dairy cow.
What is not well understood is the complex digestion and outflow of carbohydrates in the rumen of dairy cows. Understanding how DDGS is digested will improve the utilization of DDGS in dairy cattle diets.
In the first experiment, Ranathunga examined the effect of feeding DDGS (18 percent DDGS) under different forage concentrations (17 percent forage NDF vs. 24 percent forage NDF) with comparison to diets with corn starch (0 percent DDGS).
This experiment demonstrated that lactating dairy cows fed DDGS performed similarly to diets fed corn starch. This strengthened his previous findings that DDGS can be used as an energy source to replace corn starch.
It was observed that low forage fiber concentration may cause milk fat depression irrespective of whether DDGS was included in the diet. These findings suggest that lactating dairy cow diets can be formulated to include 20 percent (DM basis) of DDGS, along with adequate forage fiber (less than 21 percent) to prevent adverse conditions such as milk fat depression while maintaining greater milk production.
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The second experiment was conducted with cannulated cows to investigate the effects of concentrations of forages and DDGS on fermentation pattern in the rumen, rumen digestion kinetics, blood parameters, and total digestibility of nutrients.
This study demonstrated that concentration of forage and DDGS affects ruminal fermentation and blood parameters, but not the total tract digestibility.
The third experiment was designed to investigate the in situ degradability of TMR --containing different levels of DDGS with high or low forage levels and to investigate the in situ degradability of DDGS under different ruminal conditions.
This study showed that NDF of DDGS and TMR containing DDGS degraded poorly under low forage fiber conditions and confirmed the observation of poor NDF digestibility as observed with rumen evacuation data.
Ranathunga has already presented five abstracts, published two peerreviewed journal articles and four more articles are in preparation.
