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