Effect of postweaning heifer development system on average daily gain, pregnancy rates, and subsequent feed efficiency as a pregnant heifer

Abstract

A 3-yr study utilized 300 Angus-based, spring-born heifers to evaluate postweaning heifer development systems on gain, reproductive performance, and feed efficiency as a pregnant heifer. Heifers were blocked by BW and randomly assigned to graze corn residue (CR), upland range (RANGE), or were fed 1 of 2 diets in a drylot differing in energy levels: high (DLHI) or low (DLLO). Heifers developed on DLHI and DLLO were managed within the drylot for 166 d in yr 1, 150 d in yr 2, and 162 d in yr 3. Heifers developed on RANGE grazed winter range for an equivalent amount of days each yr as the DLHI and DLLO heifers. Heifers assigned to CR grazed for 103 d in yr 1, 84 d in yr 2, and 97 d in yr 3 before being transported to graze winter range for the remainder of the treatment period. All heifers were managed as a single group following the treatment period. Artificial insemination and natural mating were utilized during breeding. Percent of mature BW prior to the breeding season was greater ( = 0.02) for DLHI (67%) compared with RANGE (59%) and CR (58%). Pregnancy rates to AI were not different ( = 0.51) among treatments (59 ± 6%), and final pregnancy rates were also not different (87 ± 4%, = 0.54). A subset of AI-pregnant heifers from each treatment were placed in a Calan gate feeding system. Heifers were allowed a 20-d acclimation period before beginning the 90 d trial at approximately 170 d in gestation. Heifers were offered ad libitum hay; amount offered was recorded daily and orts collected weekly. Initial BW was not different ( = 0.58) among treatments (459 ± 11 kg). Body weight at the end of the trial (497 ± 17 kg) was also not different ( = 0.41). Intake was not different ( = 0.33), either as DMI (10.00 ± 1.07 kg) or residual feed intake (0.018 ± 0.190). There was no difference in ADG ( = 0.36, 0.42 ± 0.23 kg/d) among treatments. Although the total development cost was not different among treatments ( = 0.99), there was a $41 difference ( < 0.01) between the mean of the most expensive diet (DLHI) and the mean of the two least expensive diets (CR and RANGE). Developing heifers to a greater prebreeding BW did not influence subsequent AI or overall pregnancy rates or feed efficiency as a pregnant heifer.

Comparison of two alternate PGF2α products in two estrus synchronization protocols in beef heifers

“…A treatment × location interaction (P = 0.03) was detected for PR/AI between L1 (44 vs. 64 ± 7%, CONTROL vs. HiCON) and L2 (73 vs. 62 ± 7%, CONTROL vs. HiCON). The PR/AI achieved were similar to those reported in previous studies (Springman et al, 2017;Tibbitts et al, 2017). Final pregnancy rates were similar between treatments (P = 0.11) and did not differ (P = 0.96) by location.…”

“…Heifers were offered 0.5 mg of MGA (Zoetis Animal Health, Parsippany, NJ) pellets in their diet per day from days 1 to 14. On day 33, heifers were blocked by previous developmental treatments (Springman et al, 2017) and assigned to either CONTROL (n = 50) or HiCON (n = 50) treatment. An estrous detection patch was applied concurrently with the PGF 2α injection.…”

Impacts of Heifer Post-Weaning Intake Classification on Performance Measurements of Lactating and Non-Lactating Two-, Five-, and Eight-Year-Old Angus Beef Females

“…Springman and colleagues [16] conducted a 3-year study utilizing Angus-based heifers where heifers developed in a drylot on a high-energy diet had greater ADG and were heavier prior to breeding and had greater BW and percent of mature BW pre-breeding than range-and corn-residue-developed heifers, but no differences were observed from heifers developed in a drylot on a low-energy diet. Interestingly, pregnant heifer initial and final BW, dry-matter intake (DMI), ADG, feed efficiency, and residual feed intake (RFI) were not different between heifer development systems.…”