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Field trial of a planned breeding regimen for dairy cows, using gonadotrophin‐releasing hormone and prostaglandin F 2α
Author(s) -
Mawhinney I.,
Biggadike H.,
Drew B.
Publication year - 1999
Publication title -
veterinary record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.261
H-Index - 99
eISSN - 2042-7670
pISSN - 0042-4900
DOI - 10.1136/vr.145.19.551
Subject(s) - ice calving , prostaglandin f2alpha , insemination , fertility , regimen , estrous cycle , zoology , herd , dairy cattle , biology , medicine , prostaglandin , pregnancy , lactation , endocrinology , population , genetics , environmental health
A planned breeding regimen, using gondadotrophin‐releasing hormone (GnRH), prostaglandin F 2α , and a second dose of GnRH, followed by a fixed time insemination, was evaluated in comparison with a negative control on eight commercial dairy farms in the south of England. Fertility data were collected from the 220 cows in the planned breeding group and from 220 matched control cows inseminated at observed oestrus. The planned regimen induced visible oestrus in the vast majority of the cows, and serving the cows at this oestrus reduced the calving to conception interval by 15 days, resulting in 12 per cent more cows being pregnant by 125 days after calving, and 6 per cent more by 150 days. The results from the individual farms suggested that more benefit may be derived from using the regimen in herds with only average fertility indices. There was also evidence to suggest that the second GnRH injection was important, even in cows that came on heat and were served before the fixed time insemination.