Feeding DDGS In Increasing Dietary Proportions: Rumen Fermentation & Total Tract Digestibility

 

 

 

 

Previous research at the SDSU Dairy Science Department has shown that dried distillers grains with solubles (DDGS) are a good alternative feedstuff for growing dairy heifers. Feeding DDGS has resulted in no differences in average daily gain (ADG) or growth performance (Anderson et al., 2015; Manthey et al., 2016). Limit-feeding dairy heifers has shown to increase total tract nutrient digestibility while avoiding high ADG and over conditioning; however, most limit-fed diets that have been evaluated contain corn and soybean meal as main concentrate ingredients. Very little research has been done investigating the effects on rumen fermentation and nutrient digestibility when including greater DDGS amounts in limit-fed dairy heifer diets.

 

 

A study was recently conducted at the SDSU Dairy and Food Science Department to determine the effects on rumen fermentation and total tract nutrient digestibility of increasing DDGS in replacement of forage in limit-fed dairy heifer diets. Forty-eight Holstein heifers (199 d of age; 453 lbs of body weight) were individually fed one of three treatment diets for 16 weeks. Treatment diets included: 1) 30 % DDGS with 68.5% grass hay (30DG), 2) 40% DDGS with 58.5% grass hay (40DG), and 3) 50% DDGS with 48.5% grass hay (50DG). All diets also included mineral mix at 1.5% of dietary dry matter (DM). The DDGS contained 7.8% fat (dry matter basis). Diets were limit-fed at 2.65, 2.50, and 2.35% of body weight (dry matter basis) for 30DG, 40DG, and 50DG rations, respectively, to have similar intakes of crude protein and energy among treatments. Rumen fluid samples and fecal samples were collected during the last month of the study to determine diet effects on rumen fermentation and nutrient digestibility.

 

 

Analysis of rumen fluid demonstrated that total volatile fatty acids produced was similar among treatments but proportions of volatile fatty acids shifted with increasing amounts of DDGS (Figure 1). There was shift from acetate to more propionate production with increased DDGS. As acetate is a two carbon molecule and propionate is a three carbon molecule this indicates there may be less carbon loss as methane or carbon dioxide, suggesting that feeding increased amounts of DDGS results in more efficient rumen fermentation.