The influence of shade allocation or total shade plus overhead fan on growth performance, efficiency of dietary energy utilization, and carcass characteristics of feedlot cattle under tropical ambient conditions.

Autor: Castro-Pérez BI; Faculty of Veterinary Medicine and Zootechnics, Autonomous University of Sinaloa, Culiacán, Sinaloa 1084, México., Estrada-Angulo A; Faculty of Veterinary Medicine and Zootechnics, Autonomous University of Sinaloa, Culiacán, Sinaloa 1084, México., Ríos-Rincón FG; Faculty of Veterinary Medicine and Zootechnics, Autonomous University of Sinaloa, Culiacán, Sinaloa 1084, México., Núñez-Benítez VH; Faculty of Veterinary Medicine and Zootechnics, Autonomous University of Sinaloa, Culiacán, Sinaloa 1084, México., Rivera-Méndez CR; Sukarne Enterprise, Culiacán, Sinaloa 80300, México., Urías-Estrada JD; Faculty of Veterinary Medicine and Zootechnics, Autonomous University of Sinaloa, Culiacán, Sinaloa 1084, México., Zinn RA; Department of Animal Science, University of California, Davis, CA 95616, USA., Barreras A; Veterinary Science Research Institute, Autonomous University of Baja California, Mexicali, Baja California 21100, México., Plascencia A; Faculty of Veterinary Medicine and Zootechnics, Autonomous University of Sinaloa, Culiacán, Sinaloa 1084, México.
Jazyk: angličtina
Zdroj: Asian-Australasian journal of animal sciences [Asian-Australas J Anim Sci] 2020 Jun; Vol. 33 (6), pp. 1034-1041. Date of Electronic Publication: 2019 Aug 23.
DOI: 10.5713/ajas.19.0112
Abstrakt: Objective: The objective of this experiment was to evaluate the effect of shade allocation and shade plus fan on growth performance, dietary energy utilization and carcass characteristics of feedlot cattle under tropical ambient conditions.
Methods: Two trials were conducted, involving a total of 1,560 young bulls (289±22 kg BW) assigned to 24 pens (65 bulls/pen and 6 pens/treatment). Pens were 585 m2 with 15 m fence line feed bunks. Shade treatments (m2 shade/animal) were: i) limited shade (LS) to 1.2 m2shade/animal (LS1.2); ii) limited shade to 2.4 m2 shade/animal (LS2.4); iii) total shade (TS) which correspond to 9 m2/animal, and iv) total shade equipped with fans (TS+F). Trials lasted 158 and 183 days. In both studies, the average weekly maximum temperature exceeded 34°C.
Results: Increasing shade allocation tended (p = 0.08) to linearly increases average daily gain (ADG), and dry matter intake (DMI, quadratic effect, p = 0.03). This effect was most apparent between LS1.2 and LS2.4. Shade allocation, per se, did not affect gain efficiency or estimated dietary net energy (NE). Compared with TS, TS+F increased (p<0.05) ADG, gain efficiency, and tended (p = 0.06) to increase dietary NE. There was a quadratic effect of shade on longissimus area and marbling score, with values being lower (p<0.01) for LS2.4 than for LS1.2 or TS. Likewise, marbling score was lower for TS+F than for TS. Percentage kidney, pelvic, and heart (KPH) linearly decreased with increasing shade. In contrast, KPH was greater for TS than for TS+F.
Conclusion: Providing more than 2.4 m2 shade/animal will not further enhance feedlot performance. The use of fans in combination with shade increases ADG and gain efficiency beyond that of shade, alone. These enhancements were not associated with increased DMI, but rather, to an amelioration of ambient temperature humidity index on maintenance energy requirement.
Databáze: MEDLINE
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