Utility of alfalfa stemlage for feeding dairy heifers

Authors: SU, HUAWEI - University Of Wisconsin; AKINS, MATTHEW - University Of Wisconsin; ESSER, NANCY - University Of Wisconsin; Coblentz, Wayne; Ogden, Robin; Kalscheur, Kenneth; Hatfield, Ronald

Submitted to: Popular Publication
Publication Type: Popular Publication
Publication Acceptance Date: 2/23/2017
Publication Date: 3/9/2017
Citation: Su, H., Akins, M.S., Esser, N.M., Coblentz, W.K., Ogden, R.K., Kalscheur, K., Hatfield, R.D. 2017. Utility of alfalfa stemlage for feeding dairy heifers. Popular Publication. p. 20.

Interpretive Summary:

Technical Abstract: Dairy heifers are typically offered high-forage diets to control weight gains; however, these forage-based diets often contain significant portions of corn silage or other high-quality forages with low fiber concentrations. Inadequate concentrations of dietary fiber can lead to greater feed and energy intakes, causing excessive weight gains (> 1.8 to 2.2 lbs/day) and over-conditioning, especially for pregnant heifers that have higher potential intakes, but relatively low energy needs. For producers with confinement housing, and reduced exposure to weather and mud, over-conditioning can be further complicated by limited exercise. Excessive body condition (>3.5 on 5-point scale; ideal is 3 – 3.5) can lead to difficult calving and metabolic problems after calving. Typically, heifers will eat about 1% of bodyweight in neutral detergent fiber (NDF), so by increasing dietary NDF content, you can reduce feed intake. This has led to much research at the University of Wisconsin Marshfield Agricultural Research Station on using high fiber, low energy dilutant forages (wheat straw, eastern gamagrass, corn stover, tropical corn silage, and forage sorghums) to increase fiber and lower the energy density of heifer diets in order to better control heifer weight gains. The objective of this project was to evaluate the inclusion of alfalfa stemlage or wheat straw in diets of pregnant dairy heifers, and to compare the subsequent voluntary intakes and weight gains of those heifers to heifers consuming a control diet with no dilution. It was thought that stemlage would help control intake and weight gains in a manner similar to straw, which has been demonstrated in previous research. Alfalfa stemlage was produced by a novel leaf-stripping technology developed at the USDA Dairy Forage Research Center. The leaf stripper removed a majority of the alfalfa leaves, which could be used as a high-quality feed for lactating cows or potentially as protein sources for other livestock (poultry, swine, or fish), or for human use. The stems remaining in the field were then cut, wilted overnight, baled into large square bales, and individually wrapped. The stemlage nutrient composition was 63% dry matter (DM), 11% protein, 65% NDF, and 40% total digestible nutrients (TDN). The stemlage diet contained about 32% stemlage, 35% corn silage, and 33% haylage; the straw diet contained 31% straw, 30% corn silage, and 39% haylage; and the control diet had 56% corn silage and 44% haylage. Diets had similar protein contents (12.8% CP), but the stemlage and straw diets had 44-46% NDF and 59-61% TDN compared to 40% NDF and 67% TDN for the control diet. Each diet was fed to 3 pens of 8 pregnant dairy heifers (total of 9 pens and 72 heifers) for 56 days with intakes recorded daily and weights and body measurements taken at the beginning and end of the study. Inclusion of either dilutant forage (stemlage or straw) effectively reduced daily feed and energy intakes (average of 22.8 lb DM and 13.9 lb TDN intake) compared to control (24.9 lb DM and 16.7 lb TDN). Intakes of NDF were similar across the 3 diets at about 10 lb/day with heifers eating approximately 0.9% of bodyweight in NDF each day. The lower energy intakes resulted in more desirable weight gains for heifers offered stemlage and straw diets (2.2 lb/day) than observed for heifers offered the control diet (2.9 lb/day). As a result, heifers fed the corn silage/haylage control diet gained more condition than heifers offered the diluted diets even within the relatively short 56-day study. Digestibility of the control and straw diets were greater compared to the stemlage diet with heifers offered stemlage excreting 11.8 lb fecal DM (72 lb wet feces) compared to about 9 lb fecal DM (60 lb wet feces) for both control and straw. The increased fecal amount may be problematic when feeding high-fiber, low-digestibi