Evaluation of performance and carcass traits for a five-cohort All Heifer, No Cow beef production system demonstration herd

Fecha

2020-10-27

Tipo

artículo original

Autores

Harrison, Meredith A.
Arce Cordero, José Alberto
Seidel Jr., George E.
Archibeque, Shawn L.
Whittier, Jack C.
Rhoades, Ryan D.
Ahola, Jason K.

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Resumen

The All Heifer, No Cow (AHNC) beef production system is an alternative to con ventional cow/calf production that involves in semination of nulliparous heifers with sexed semen to produce female calves that are early weaned at 3 mo of age. Dams are finished on a high-concentrate diet and harvested before reach ing 30 mo of age. Objectives of this research were to document reproductive, feedyard, calf, and carcass performance of an AHNC herd; evaluate effects of carcass maturity on carcass quality; and determine if performance of initial cohorts (i.e., cohorts 1 and 2) differed from sustaining cohorts (i.e., cohorts 3–5). A total of 272 heifers were en rolled in the AHNC system via five annual co horts. The system was initiated with 51 yearling, Angus-based heifers, and a replicate set (n = 56) was started 12 mo after. Heifers in cohorts 3 (n = 53), 4 (n = 56), and 5 (n = 56) were primarily offspring of prior cohorts (i.e., cohort 3 heifers born to cohort 1 females), but some were pur chased to maintain inventory. Angus replacement heifers were purchased in cohorts 3 (n = 26), 4 (n = 26), and 5 (n = 28). Mean (±standard de viation) pregnancy rate at 30 d after fixed-time artificial insemination (AI) with sexed semen was 50.8% ± 9.4%, and 140-d pregnancy rate was 93.0% ± 1.5%. With AHNC, 61.0% ± 6.5% of fe males replaced themselves with a heifer. During finishing, average daily gain (ADG) was 1.9 ± 0.4 kg • d−1 and dry matter intake (DMI) was 14.9 ± 1.9 kg • d−1. Hot carcass weight (HCW) was 367 ± 35 kg. The USDA grading system clas sified 20.5% of all carcasses (n = 220) as C ma turity (A00 = 100, B00 = 200, etc.), 62.4% ± 29.1% of carcasses as USDA Choice. USDA yield grade (YG) was 2.6 ± 0.7. Based on cohorts 1 and 2, there were no differences (P = 0.96) in Warner– Bratzler shear force values between A and B ma turity vs. C maturity carcasses. Across all cohorts, there were no differences in USDA YG, marbling score (MA), and lean maturity between A and B maturity vs. C maturity carcasses; there were differences in age (P < 0.001), bone maturity (P < 0.001), and overall maturity (P <0.001). A comparison of initial vs. sustaining cohorts showed that initial cohorts had lower (P < 0.001) DMI, heavier (P < 0.001) HCW, and more ad vanced (P < 0.05) bone maturity. However, there were no differences for 30- and 140-d pregnancy rates, ADG, USDA YG, and MA between initial and sustaining cohorts. The AHNC beef produc tion system can effectively produce female calves and quality carcasses for harvest.

Descripción

La Universidad de Costa Rica apoyó el programa de doctorado de José Alberto Arce Cordero

Palabras clave

Beef production system, Biological efficiency, CATTLE, Sex-selected semen, Single-calf heifer

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