Comparison of feeding diets diluted with sorghum-sudangrass silage or low-quality grass on nutrient intake and digestibility and growth performance of Holstein dairy heifers

Authors: LI, LINGYAN - University Of Wisconsin; AKINS, MATTHEW - University Of Wisconsin; ESSER, NANCY - University Of Wisconsin; Ogden, Robin; Coblentz, Wayne

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2019
Publication Date: 10/11/2019
Citation: Li, L., Akins, M.S., Esser, N.M., Ogden, R.K., Coblentz, W.K. 2019. Comparison of feeding diets diluted with sorghum-sudangrass silage or low-quality grass on nutrient intake and digestibility and growth performance of Holstein dairy heifers. Journal of Dairy Science. 102(11):9932-9942. https://doi.org/10.3168/jds.2018-16168.
DOI: https://doi.org/10.3168/jds.2018-16168

Interpretive Summary: Feeding strategies for pregnant dairy heifers are often based on a high-forage, moderate-energy rations to control intakes, gains, and body condition. This can reduce the economic and environmental expense without affecting their future lactating performance. Sorghum-sudangrass silage usually has a moderate energy density with high fiber concentrations and high yield potential, which make it an excellent forage source to be used in heifer rations. Our study revealed that sorghum-sudangrass silage based forage diets can control the dry matter and energy intake by heifers and maintain optimum body condition and growth without negative effects on nutrient digestibility, and therefore can be useful in an ad-libitum heifer feeding program.

Technical Abstract: This study was carried out to evaluate the nutrient intakes and growth of dairy heifers offered an alfalfa silage–corn silage diet (CON; 14.3% crude protein, 61.1% total digestible nutrients, 47.9% neutral detergent fiber) compared with diets containing 1 of 2 types of sorghum sudangrass (SS) silages: conventional or photoperiod sensitive. The objective of the study was to determine the potential to use SS to control dry matter (DM) and nutrient intakes and weight gain. Both diets were similar in nutrient composition, with approximately 13% crude protein, 60 to 61% total digestible nutrients, and 55% neutral detergent fiber. Seventy-two Holstein heifers (16–18 mo at study initiation) were blocked by initial body weight (light = 422 ± 12.8 kg; medium = 455 ± 14.8 kg; heavy = 489 ± 16.7 kg) with 3 pens assigned to each weight block (8 heifers/pen; 24 heifers/block). The 3 diets were randomly allocated to the pens within each block and offered for 12 wk. Heifers offered the CON diet had greater DM, protein, and energy intakes compared with those offered the SS silage-based diets due to the greater neutral detergent fiber concentration of the SS diets. With lower DM and nutrient intakes, average daily gain was in the recommended range (0.8–1.0 kg/d for Holstein heifers) for heifers offered the SS silage-based diets (mean of 0.92 kg/d for both SS diets vs. 1.11 kg/d for CON). Sorting behaviors for heifers offered both SS diets were more aggressive against long, medium, and short particles compared with those of heifers offered the CON diet; however, heifers sorted large particles from photoperiod-sensitive silage more aggressively than those from conventional silage. Based on this study, SS silage-based diets can control the DM and energy intakes for heifers and maintain optimum growth rates, with harvesting at a shorter chop length likely helping to alleviate sorting issues.