|LI, LINGYAN - Heilongjiang Bayi Agricultural University (HLAU)|
|ESSER, NANCY - University Of Wisconsin|
|AKINS, MATTHEW - University Of Wisconsin|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/13/2019
Publication Date: N/A
Technical Abstract: Pregnant dairy heifers can overconsume energy when fed diets with lower fiber levels causing higher intakes. Use of high fiber forages can help control intake and gains. The objective of the study was to determine the potential to use sorghum-sudangrass (SS) to control DM and nutrient intakes and weight gains. This study evaluated the nutrient intakes and growth of dairy heifers offered an alfalfa silage/corn silage diet (CON; 14.3% CP, 61.1% TDN, 47.9% NDF) compared with diets containing 1 of 2 types of SS silages [conventional (CSS) or photoperiod sensitive (PSS)]. Both diets were similar in nutrient composition, with approximately 13% CP, 60 to 61% TDN, and 55% NDF. Seventy-two Holstein heifers (16 to 18 mo old 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 weeks. Data were analyzed as a randomized complete block design using Proc Mixed of SAS v9.4. Heifers offered CON had greater DM (10.9 kg DM/d), protein (1.51 kg CP/d), and energy intakes (6.68 kg TDN/d; P < 0.01) compared with both SS silage based diets (9.14 kg DM, 1.16 kg CP, 5.54 kg TDN/d) due to the greater NDF concentration of the SS diets. With lower DM and nutrient intakes, average daily gain was in the recommended range of gains (0.8 to 1 kg/day 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; P = 0.02)). Sorting behaviors for heifers offered either SS diet were more aggressive against long particles and preference for medium and short particles compared with CON (P < 0.01); however, heifers sorted large particles from PSS more aggressively than those from CSS (P < 0.05). 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.