|Akins, M. - University Of Wisconsin|
|Williams, K. - University Of Wisconsin|
|Su, H. - University Of Wisconsin|
|Esser, N. - University Of Wisconsin|
|Hoffmann, P. - Vita Plus Corporation|
|Weigel, K. - University Of Wisconsin|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/6/2017
Publication Date: 6/25/2017
Citation: Akins, M., Williams, K., Su, H., Coblentz, W.K., Esser, N., Hoffmann, P., Weigel, K. 2017. Effect of limit feeding and genomic residual feed intake on bred dairy heifer performance. Journal of Dairy Science. 100 (suppl. 2):272.
Technical Abstract: The objective of this study was to evaluate growth, intake, and feed efficiency of dairy heifers with different predicted genomic residual feed intakes as lactating cows (RFI) offered diets for ad-libitum intake or limit-fed. Post-bred Holstein heifers (128, ages 14-20 months), were blocked by initial weight (high, 516 kg; medium-high, 485 kg; medium-low, 457 kg; and low, 420 kg) with 32 heifers per block. Each weight block was sorted by RFI (High, Low) to obtain 2 pens of High and 2 pens of Low RFI for each block (8 heifers per pen). Low RFI heifers were expected to have greater feed efficiency than High RFI. Diet treatments were i) a control diet comprised of alfalfa haylage and corn silage offered for ad-libitum intake (CON; 59.2% TDN, 12.7% CP, and 47.8% NDF, DM basis), and ii) a diet limit-fed to 90% of CON intakes with similar forages as CON, but corn and soybean meal were added to equalize nutrient intakes across diets (LIMIT; 62.4% TDN, 13.4% CP, and 42.7% NDF, DM basis). Each treatment was randomly allocated to obtain a 2x2 factorial arrangement of 2 RFI levels and 2 diet treatments. Diets were fed in a 120-d trial. Statistical analysis was conducted using the MIXED procedure in SAS 9.4 with pen as experimental unit. Intake was affected by diet (11.0 vs. 9.98 kg DM/d for CON and LIMIT, respectively; P=0.01) but not by RFI or their interaction (P>0.34). Daily gain was affected by diet with CON having greater gains than LIMIT (0.88 vs 0.80 kg/d; P<0.01) potentially due to greater digesta fill for ad-libitum fed heifers. Daily gain was also affected by RFI with Low RFI gaining more than High RFI (0.86 vs. 0.83 kg/d; P<0.01). Feed efficiency was not affected by diet (P=0.70), but was better for Low RFI than High RFI (12.1 vs. 12.8 kg DM/kg; P=0.01). Body condition gain was not affected by RFI or diet (P>0.36). Protein intake was greater for CON than LIMIT (1.41 vs. 1.33 kg CP/d; P=0.04). Intake of digestible and metabolizable energy tended to be greater for CON than LIMIT (P=0.07); but not for net energy for maintenance or gain (P>0.28). Overall, Low RFI heifers had improved efficiency whether fed ad-libitum or limit-fed.