Relationships among performance, residual feed intake, and temperament assessed in growing beef heifers and subsequently as 3-year-old, lactating beef cows1

Abstract

Seventy-four beef heifers were used to evaluate relationships among performance, residual feed intake (RFI), and temperament measured as growing heifers (Phase 1) and subsequently as 3-yr-old lactating beef cows (Phase 2) in the same cohort. In both phases, females were housed in a covered facility and fed similar forage-based diets, and individual feed intakes, BW, BCS, chute scores (CS), exit velocities (EV), and pen scores (PS) were collected throughout the 70-d feeding trials. In Phase 2, cows were milked on trial d 14 (lactation d 28 ± 3.5) and trial d 70 (lactation d 84 ± 3.5) to determine energy-corrected milk (ECM) production. Ultrasonic backfat thickness (BF), and ribeye area (REA) were evaluated on d 0 and 70 of the trial in Phase 2. Heifers were ranked by RFI and placed into Low (<0.5 SD mean RFI; n = 27), Medium (within ± 0.5 SD; n = 23), and High (>0.5 SD mean RFI; n = 24) RFI groups. Body weight, BCS, and ADG were similar among all RFI groups; however, daily DMI differed for all groups (P < 0.01) and was greater (10.76 ± 0.24 kg/d) for High, intermediate (9.88 ± 0.25 kg/d) for Medium, and less (8.52 ± 0.23 kg/d) for Low RFI heifers. When cow performance was analyzed based on RFI rank as heifers, BW, BCS, ADG, RFI, d 14 and d 70 ECM, BF, and REA were similar among RFI groups; however, cows that were most efficient as heifers (Low) had decreased (P < 0.05) daily DMI values (10.30 ± 0.41 kg/d) compared with cows that ranked Medium (11.60 ± 0.44 kg/d) or High (11.50 ± 0.43 kg/d) as heifers. The Pearson rank correlation between Phase 1 and 2 RFI was r = 0.13 (P = 0.30), and Pearson rank correlations showed no relationship (P > 0.1) between RFI and temperament. Phase 1 CS was negatively associated with ADG in Phase 1 (r = -0.28; P = 0.02) and 2 (r = -0.32; P = 0.01), and positively associated with d 14 (r = 0.24; P = 0.04) and 70 (r = 0.25; P = 0.03) ECM. Phase 2 CS was negatively associated with Phase 2 ADG (r = -0.29; P = 0.01) and positively associated with d 14 (r = 0.46; P = 0.001) and 70 (r = 0.33; P = 0.004) ECM. Phase 2 PS also tended to be negatively associated with DMI in Phase 1 (r = -0.20; P = 0.096) and 2 (r = -0.20; P = 0.08). In this study, heifers that were most feed efficient subsequently consumed less feed as lactating cows and maintained similar performance. Feed efficiency was not associated with differences in temperament; however, more excitable females had poorer BW gains and tended to have reduced feed intakes but produced more ECM.

A glimpse of the future in animal nutrition science. 2. Current and future solutions

“…A low negative genetic correlation between heifer RFI and mature cow weight (r g = -0.22) was observed, indicating that favorable selection based on post-weaning RFI will improve efficiency of feed utilization in cows with minimal effects on mature size. These results and those from more recent studies (Arthur et al, 2005;Basarab et al, 2007;Black et al, 2013;Hafla et al, 2013;MacDonald et al, 2014) demonstrate that post-weaning RFI of heifers is favorably associated phenotypically with efficient feed utilization by gestating and lactating cows, with minimal effects on productivity or reproductive performance. However, favorable selection for RFI may delay the onset of puberty in heifers, thereby increasing the age at first conception without negatively affecting subsequent reproductive performance of cows (Arthur et al, 2005;Basarab et al, 2007;Donoghue et al, 2011).…”

Relationships among temperament, behavior, and growth during performance testing of bulls1

“…Bulls have greater growth rates and have larger REA than heifers of the same age and sire (Hedrick et al, 1969), and accelerated growth rate may have led to larger variations in REA among the bulls in this study. The heifers in the study conducted by Black et al (2013) were a mixture of Bos taurus and Bos indicus breed types, whereas the bulls in the present study were B. taurus and were a uniform group of Angus bulls for comparison of body conformation measurements.…”

“…The REA was larger for bulls categorized as EVcalm when compared with EVexcitable bulls. Black et al (2013) assessed temperament in heifers of different breed types every 2 wk over a 70-d period by evaluating both PS and EV and concluded that REA did not differ due to temperament. Gender and breed differences may explain these conflicting results.…”

Invited review: Improving feed efficiency in dairy production: challenges and possibilities

“…To date, no studies have evaluated RFI in dairy cows during the dry period or the relationship between RFI during growth or lactation and subsequent feed intake, BW or body condition during the dry period. However, RFI in beef heifers during growth was found to have a positive phenotypic correlation (r p ; P < 0.05) with forage DMI (r p = 0.38) and RFI (r p = 0.42) during pregnancy (Hafla et al, 2013), and a positive correlation with DMI (r p = 0.21; P < 0.07) during the subsequent lactation (Black et al, 2013). Thus, RFI appears to be repeatable over different stages of the production cycle of beef cattle and similar relationships may exist among dairy cattle.…”