ARS | Publication request: Evaluation of limit feeding and bunk management for gravid dairy replacement heifers

Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: May 2, 2011
Publication Date: July 11, 2011
Citation: Esser, N.M., Larson, J., Hoffman, P.C., Lui, C.L., Coblentz, W.K. 2011. Evaluation of limit feeding and bunk management for gravid dairy replacement heifers. Journal of Dairy Science. 375.

Technical Abstract: To assess effects of bunk access and limit feeding on dairy heifer growth and nutrient intake, 96 Holstein heifers (394 ± 31 kg) were fed one of two diets, and allotted to full (F) or partial (P) bunk access. Pens (n=12) of heifers were limit fed a TMR without (NS) straw or fed a TMR with straw (S). Feed access times for NS and S were 6 and 24 h respectively. Heifers, fed NS or S, were assigned to pens with F (8 stalls/8 heifers) or P (4 stalls/8 heifers) to complete the 2X2 factorial arrangement (FS, PS, FNS, PNS). Heifers were evaluated for growth, and nutrient intake. Bunk occupancy time and rate, 0-6 h post-feeding, were evaluated using timed digital photography. Data were analyzed using PROC MIXED with pen replication as the experimental unit. Bunk occupancy for F heifers was longer (P<0.01; 149.8 vs 111.2 min) than heifers allotted to P. Feeding S (S vs NS) increased (P<0.02) heifer bunk occupancy by 16.2 min. Bunk occupancy rate was 27.6, 20.0, 24.4 and 18.1 min/h for FS, PS, FNS and PNS respectively. Dietary NDF increased 7.0 % units by feeding S and decreased (P<0.04) DMI of heifers 0.28 kg/d as compared to limit feeding NS. Heifers fed S consumed 0.55 kg more (P<0.01) NDF/d but consumed less (P<0.01) CP, and Mcals of ME than heifers fed NS. Bunk access (F vs P) had no effect (P>0.55) on DMI or the intake of any nutrient. Despite lower CP and ME intakes, the ADG of heifers fed S or NS were similar (P>0.21; 0.90 vs 0.95 kg/d). Allotting heifers to F or P bunk access likewise had no effect (P>0.39) on ADG (0.95 vs 0.91 kg/d) and no interactions between bunk access and treatment diet on ADG were observed. Finally, bunk occupancy rate (min/h) and ADG were regressed using PROC REG procedures. For heifers assigned to PS (r2=0.25) and FNS (r2=0.15) there were weak positive relationships between bunk occupancy rate and ADG. For heifers assigned to FS or PNS there was no relationship between bunk occupancy rate and ADG. Data suggest adding straw to a limit fed diet with partial bunk access does not improve heifer nutrient intake, and induces a more variant relationship between bunk occupancy rate and ADG.