Field trials on hexoestrol implantation of steers on New Zealand farms

Abstract

Field trials on hexoestrol implantation were conducted in the Waikato area of the North Island of New Zealand during 1958–59, involving 260 two and three year old Aberdeen Angus steers from nine farms. Two levels of hormone implantation were studied, namely, 30 and 45 mg. The trials ranged in duration from three to five months with an average of four months.Pronounced differences were apparent between farms in the overall growth rates and carcass quality scores of the cattle.Hexoestrol implantation led to a significant increase in carcass weight, estimated at approximately 22 lb., with little evidence of real differences between farms in the average response to the hormone.Response to the higher as compared with the lower dose of hexoestrol varied markedly among the separate farms. In general, the lower dose of 30 mg. tended to yield the greater increase in carcass weight.A small, but consistent, depression of carcass quality scores was manifest under hormone treatment, with no real differences between the two dosage levels.