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Effects of growth rate during the early fattening period on growth, carcass characteristics and circulating hormones in the different growth hormone genotypes of Japanese black steers
Author(s) -
OKA Akio,
IWAKI Fumiyuki,
IWAMOTO Eiji,
TATSUDA Ken
Publication year - 2007
Publication title -
animal science journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.606
H-Index - 38
eISSN - 1740-0929
pISSN - 1344-3941
DOI - 10.1111/j.1740-0929.2007.00418.x
Subject(s) - growth hormone , valine , biology , zoology , medicine , hormone , insulin like growth factor , endocrinology , leucine , genotype , body weight , amino acid , growth factor , biochemistry , gene , receptor
One of the bovine growth hormone (GH) genetic variants is a substitution of leucine (Leu) to valine (Val) at amino acid position 127 of the protein. The GH genotypes of 14 Japanese black steers used in the present study were Leu/Leu (A, n = 7) and Val/Val (B, n = 7). The steers in each genotype group were divided into two groups based on intended growth rate (high, 1.0 kg/day; low, 0.6 kg/day) during 10–17 months of age. The overall mean concentration of plasma GH was higher ( P < 0.05) in the A group than in the B group. The serum concentration of insulin‐like growth factor‐I was higher ( P < 0.05) in the B group than in the A group. The carcass weight of the A group was greater ( P < 0.01) than that of the B group. However, there was no significant difference in carcass weights between the 1.0 kg/day and 0.6 kg/day groups ( P > 0.05). The rib thickness of the 1.0 kg/day group was greater ( P < 0.05) than that of the 0.6 kg/day group. The crude fat content of longissimus muscle was greater ( P < 0.05) for the 0.6 kg/day group compared with the 1.0 kg/day group.