This is not a peer-reviewed article. Livestock Environment VIII Proceedings of the 31 August - 4 September 2008 Conference (Iguassu Falls, Brazil) Publication Date 31 August 2008 ASABE Publication Number 701P0408
Artificial Shade Effects in the Performance and Physiology of Dairy Heifers in Pasture M. N. D. Conceição¹, I. J. O. D. Silva², and C. T. D. S. Dias³ 1 2
Doutoranda – ESALQ/USP. Bolsista da CAPES, Brazil
Departamento de Engenharia Rural - ESALQ/USP, Brazil, E-mail:
[email protected] 3
Departamento de Ciências Exatas - ESALQ/USP, Brazil
Abstract. A more accurate accounting of the effect of environment on milk production or growth rate is needed to diagnose performance problems and to make decisions about facility design and pasture systems. This work was undertaken to study the effects of the three roofed shading types during summer in Brazil tropical conditions on some physiological functions related to the heat dispersing process like rectal temperature, respiratory frequency, and infrared skin temperature, as well as the body weight gain of growing dairy heifers in pastures. Sixteen Holstein heifers and sixteen Holstein x Jersey cross heifers (initially weighing 263 ±66 kg) were kept for a 142-day period, during the hot times of the day in sixteen adjacent pens, in four randomized blocks. The roof types were: galvanized steel, asbestos cement, and polypropylene shade cloth graded ‘80% shade’. The pens were shaded with a roof (4 m high), allowing for 4.0 m2 of shade/heifer. All animals were submitted to identical management. The results obtained showed differences in the treatments (p
