Young Scholar Presentation: Feeding Peripubertal Dairy Heifers Diets High in Distillers Grains with Varying Forage to Concentrate Ratios

Two studies were conducted to evaluate the effects of limit-feeding peripubertal dairy heifers distillers dried grains with solubles (DDGS) with varying forage to concentrate ratios. The first study determined the effects of increasing the inclusion amount of DDGS on growth, rumen fermentation, nutrient digestibility, metabolic profile, onset of puberty, and post-trial performance. The second study determined performance of heifers when fed DDGS or control grain mix with ad libitum grass hay. Both were 16-wk, randomized complete block design, feeding studies with heifers individually fed using Calan gates. Data were analyzed using the MIXED procedures of SAS 9.4 with repeated measures and significance declared at P < 0.05 and tendencies declared at P < 0.10. The first study had 48 Holstein heifers and treatments were 1) 30% DDGS, with diet fed at 2.65% of body weight (BW) (30DG), 2) 40% DDGS, with the diet fed at 2.50% of BW (40DG), and 3) 50% DDGS, with the diet fed at 2.35% of BW (50DG). The remainder of the diets were grass hay and 1.5% mineral mix. There were no differences in growth parameters; however, gain: feed and nutrient digestibility increased with increasing amounts of DDGS. Plasma total fatty acids and polyunsaturated fatty acids were linearly increased with a quadratic response with 30DG and 50DG having the greatest concentrations. There was a quadratic response of plasma urea nitrogen and a quadratic tendency for cholesterol. Age and BW at puberty were similar among treatments, although there was treatment by age interaction. Post-trial data were collected on reproductive and lactation performance, which were comparable among treatments. The second study had 24 heifers (18 Holstein, 6 Brown Swiss) and treatments were 1) corn and soybean product concentrate mix (CON) and 2) DDGS concentrate mix (DDG). Both concentrate mixes were limit-fed at 0.8% of BW and grass hay was fed ad libitum. Dry matter intake and growth parameters were similar; however, rumen fermentation and metabolic profile differed. Results from these studies demonstrated that DDGS can be included at 30, 40 or 50% in replacement of hay in limit-fed diets or can be fed in replacement of corn and soybean meal with ad libitum grass hay and maintain growth performance of peripubertal heifers with some shifts in metabolic profile without detriment to subsequent performance.