Behavior of 3 breeds of heifers exposed to sun and to shade at vicosa minas gerais brazil 2. blood components and weight gains

Oliveira, J.S.E.; Milagres, J.C.; Cardosa, R.M.; Castro, A.C.G.

Revista da Sociedade Brasileira de Zootecnia 9(1): 72-89

1980


Accession: 004814632

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Abstract
Behavior of Holstein (H), 1/2 Holstein-Zebu (1/2 HZ) and 3/4 Holstein-Zebu (3/4 HZ) heifers under shaded and nonshaded environments was studied at the Universidade Federal de Vicosa (Minas Gerais), Brazil. Six heifers of each of the 3 groups were equally distributed into the 2 environments. Average air temperature in the three 28 day periods was 22.4.degree., 20.8.degree. and 17.4.degree. C with relative humidities of 73.0, 74.0 and 72.6%, respectively. Hb, number of erythrocytes (Er) and body weights were measured in the heifers. The 1/2 HZ heifers showed higher values of Hb and Er than the 3/4 HZ heifers. The purebred Holstein heifers showed the lowest values. Values were higher for heifers kept under shade than for those in nonshaded environment. Values were lower in period I than in periods II and III which did not differ. Gain in body weight was higher in period I than in periods II and III but did not differ among the groups of heifers and between the enviroments. Results in body weight gain indicate that under these conditions physiological comfort of shaded environment is not justification to build shade for diary heifers.