Impact of brown-midrib Corn ShredlageŽ on lactation performance by dairy cows

Abstract Text: The experimental objective was to evaluate the effect of feeding TMR containing brown-midrib (BMR) Corn Shredlage® (SHRD) compared to conventional-processed BMR corn silage (KP) or KP with chopped alfalfa hay (KPH) on lactation performance by dairy cows. The SHRD was harvested using SHRD processing rolls (2-mm roll gap) in a Claas 940 self-propelled forage harvester (SPFH) set for 26-mm theoretical length of cut (TLOC), while KP was harvested using conventional processing rolls (2-mm roll gap) in the same SPFH set for 19-mm TLOC. Sample DM contents and mean particle lengths during feed-out were 39.0% ± 4.3 and 10.0 mm ± 0.7 versus 38.4% ± 3.5 and 11.4 mm ± 0.8 for KP versus SHRD. One hundred twenty cows (81 + 28 DIM and 717 + 19 kg BW at trial initiation) stratified by parity, DIM and milk yield were randomly assigned to 15 pens of 8 cows each. Pens were randomly assigned to one of the three TMR treatments            in a 16-wk continuous-lactation trial which included a 2-wk covariate adjustment period. The SHRD and KP TMR contained (DM basis) SHRD or KP (45%), alfalfa haylage (10%), and concentrate mix (45%). The KPH TMR contained (DM basis) KP (35%), alfalfa haylage (10%), chopped alfalfa hay (10%), and concentrate mix (45%). Data were analyzed using Proc Mixed in SAS with covariate, treatment, week, and treatment x week interaction as Fixed effects and pen within treatment as a Random effect. Dry matter intake and time spent ruminating were unaffected (P>0.10) by treatment and averaged 26.8 kg/d and 502 min/d, respectively. Milk (50.7 kg/d on average) and lactose (2.47 kg/d on average) yields were greater (P<0.001) for SHRD and KP versus KPH (47.4 kg/d milk and 2.31 kg/d lactose). Average daily milk yields were 51.3 and 50.1 kg/d for SHRD and KP, respectively. A treatment by week interaction (P<0.001) was observed for milk yield which was 1.5 kg/d greater, on average, for SHRD than KP during weeks 3, 7, 8, 9, 12 and 14 of the treatment period. Milk fat content was greater (P<0.05) for KPH (3.67%) than SHRD and KP (3.31% and 3.29%, respectively). Reduced milk fat content for SHRD versus KPH suggests that the greater TLOC in BMR SHRD did not increase physically effective fiber when compared to chopped hay. Milk and component yield responses to SHRD over KP were observed for several treatment weeks.

Keywords: corn silage, dairy cows, shredlage