Growth performance and carcass characteristics in finishing feedlot heifers fed different levels of chromium-enriched live yeast or fed zilpaterol hydrochloride

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Yissel S. Vald?z-Garc?a
J. I. Aguilera-Soto
A. Barreras
A. Estrada-Angulo
A. G?mez-Vazquez
A. Plascencia
Julio J. Reyes
Justiniano Stuart
Noem? G. Torrentera

Abstract

Sixty crossbred heifers (371 ? 7 kg) were used in a 63-d feeding trial (4 pens per treatment in a randomized complete block design) to evaluate the influence of dietary supplementation with zilpaterol hydrochloride (?-agonist) or with different levels of chromium-enriched live yeast (Cr-YC) on growth performance and carcass characteristics. Heifers were fed a diet based on steam-flaked corn (1.45 Mcal of net energy of gain, NEg kg-1). Treatments were: 1) control, no yeast, no zilpaterol supplementation (Ctrl); treatments 2, 3 and 4) were the same basal diet supplemented with a commercial Cr-YC for a final dose of 10, 20 or 30 g hd-1 d-1 of yeast strain, and 5) the same basal diet (Ctrl) supplemented with 6 mg of zilpaterol kg-1 of feed for 30 d (ZIL), drug withdrawn from the diet 3 d pre-harvest. Compared with controls, ZIL increased final weight (3.8 %, P < 0.03), carcass-adjusted daily gain (18.7 %, P = 0.05), apparent dietary net energy of maintenance (14 %, P < 0.01), and decreased observed/expected DMI (14 %, P < 0.01). Treatment with ZIL did not affect (P < 0.13) marbling score, but, compared with control group, increased carcass dressing percentage (2.6 %, P = 0.01), and reduced (P = 0.02) kidney, pelvic and heart fat (KPH, 19.8 %) and fat thickness (9.4 %) and tended (5.9 %, P = 0.06) to increase Longissimus muscle area. Compared with Cr-YC treatments, ZIL increased apparent dietary NEm (P = 0.03) and dressing percentage (P < 0.01), and decreased observed/expected DMI (P = 0.03) and KPH (P=0.04). Treatment with Cr-YC did not affect carcass characteristics, but compared with control, Cr-YC supplementation tended to increase final BW (P = 0.08), ADG (0.09), fed:gain ratio (F:G, P = 0.08) and dietary NE (P = 0.06). Level of supplemental Cr-YC increased (linear component, P ? 0.04) final BW, ADG, F:G, apparent dietary NEm, and decreased (P = 0.02) observed/expected DMI. Level of supplemental Cr-YC did not affect (P ? 0.33) dressing percentage, LM area or marbling score, but, fat thickness and KPH decreased (P = 0.02) as Cr-YC level supplementation increase. DMI and HCW tended (P ? 0.08) to increase with increasing Cr-YC supplementation level. It is concluded that, zilpaterol supplementation increase growth performance in heifers as results of greater muscle accretion and for reduction of body fat. Chromium-enriched yeast supplementation increase growth performance and dietary NE, with modest effect in carcass characteristics. Better responses were observed at level of Cr-YC supplementation of 30 g hd-1 d-1 that corresponds to daily intakes of 1.65 ? 1011 colony forming units and 15 mg chromium.
Key words: finishing cattle, ?-agonist, direct-fed microbials, feed efficiency, carcass traits.

Article Details

How to Cite
Vald?z-Garc?a, Y. S., Aguilera-Soto, J. I., Barreras, A., Estrada-Angulo, A., G?mez-Vazquez, A., Plascencia, A., Reyes, J. J., Stuart, J., & Torrentera, N. G. (2011). Growth performance and carcass characteristics in finishing feedlot heifers fed different levels of chromium-enriched live yeast or fed zilpaterol hydrochloride. Cuban Journal of Agricultural Science, 45(4). Retrieved from https://www.cjascience.com/index.php/CJAS/article/view/94
Section
Animal Science
Author Biographies

Yissel S. Vald?z-Garc?a

Instituto de Investigaciones en Ciencias Veterinarias, Universidad Aut?noma de Baja California, Mexicali 21100, Baja California, M?xico.

J. I. Aguilera-Soto

Unidad Acad?mica de Medicina Veterinaria y Zootecnia, Universidad Aut?noma de Zacatecas, El Cordovel Enrique Estrada, Zacatecas, 98500, M?xico.

A. Barreras

Instituto de Investigaciones en Ciencias Veterinarias, Universidad Aut?noma de Baja California, Mexicali 21100, Baja California, M?xico.

A. Estrada-Angulo

Facultad de Medicina Veterinaria y Zootecnia, Universidad Aut?noma de Sinaloa, Culiac?n 1084, Sinaloa, M?xico.

A. G?mez-Vazquez

Divisi?n Acad?mica de Ciencias Agropecuarias, Universidad Ju?rez Aut?noma de Tabasco, km 25 Villahermosa-Teapa, Tabasco, M?xico

A. Plascencia

Instituto de Investigaciones en Ciencias Veterinarias, Universidad Aut?noma de Baja California, Mexicali 21100, Baja California, M?xico.

Julio J. Reyes

Departamento de Rumiantes, Instituto de Ciencia Animal, km 47.5 Carretera Central, Mayabeque, Cuba

Justiniano Stuart

Departamento de Rumiantes, Instituto de Ciencia Animal, km 47.5 Carretera Central, Mayabeque, Cuba

Noem? G. Torrentera

Instituto de Investigaciones en Ciencias Veterinarias, Universidad Aut?noma de Baja California, Mexicali 21100, Baja California, M?xico.