97 Effects of Creep Feed Duration in a Drylot System on Cow Performance and Reproduction as Well as Calf Performance Through Receiving

Abstract

Abstract The objectives were to determine effects of creep feed duration in drylot-housed, cow-calf system on cow performance and reproduction as well as calf performance through receiving phase. Spring-calving, Simmental × Angus cows (5 ± 2 yr; n = 72) were stratified by calf age (83 ± 14 d), sex, and body weight (BW; 130 ± 17 kg) and allotted to 12 pens with six cow-calf pairs per pen. Pens were randomly assigned to 1 of 2 treatments: calves fed commercial, pelleted creep feed (14% CP) for 105 d (105dCF) or final 21 d (21dCF) prior to weaning. Cow-calf pairs were housed on concrete drylots with open-front buildings for the pre-weaning period. Cows were limit fed at maintenance a total mixed ration. Ultrasound measurements for carcass composition of calves were collected on d 104. Calves were abruptly weaned on d 105 and transported 263 km to a feedlot for the receiving phase. Pen assignments remained for the 6-week receiving period. Calves had ab libitum access to a receiving ration that consisted of corn silage, modified wet distillers grains, grass hay, dry corn, and supplement. Reproduction data were analyzed using GLIMMIX and all other response variables were analyzed using the MIXED procedure of SAS 9.4. There were no differences (P ≥ 0.11) in cow BW, BCS, milk production, milk composition, or reproductive data. The 105dCF calves had greater (P ≤ 0.01) ADG from d 0 to 105 and BW than 21dCF (286 vs. 258 kg, respectively). The 105dCF calves had greater (P ≤ 0.01) longissimus muscle area, rib fat, and rump fat compared with 21dCF; however, intramuscular fat was not different (P = 0.20) between treatments. During the receiving phase, there were no differences (P ≥ 0.23) in dry matter intake. In the first 4 weeks of receiving there were no differences (P ≥ 0.73) in ADG; however, in the final 2 weeks 21dCF calves had greater (P = 0.02) ADG. The 21dCF calves had greater (P = 0.01) ADG during the overall receiving period. There were no differences (P ≥ 0.86) in gain to feed (G:F) for the first four weeks of receiving. The 21dCF calves had greater (P = 0.03) G:F for the final two weeks and tended to have greater (P = 0.08) G:F during overall receiving. However, the 21dCF calves (324 kg) were still lighter (P ≤ 0.01) BW than 105dCF (340 kg) at end of receiving. In conclusion, creep feed duration did not impact cow performance or reproduction. The 105dCF calves had increased ADG and BW for the pre-weaning period. Although the 21dCF calves had increased gain and feed efficiency at the end of receiving, the 105dCF calves remained the heavier for the duration of the experiment.