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Gonadotropin‐Releasing Hormone Administration to Dairy Cows without a Corpus Luteum 4 Weeks after Calving Increases Reproductive Performance
Author(s) -
Jeong JK,
Kang HG,
Hur TY,
Kim IH
Publication year - 2013
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/rda.12188
Subject(s) - corpus luteum , ice calving , insemination , zoology , artificial insemination , medicine , gonadotropin releasing hormone , pregnancy , endocrinology , andrology , biology , hormone , lactation , luteinizing hormone , sperm , genetics
Contents This field study investigated whether the administration of a single dose of gonadotropin‐releasing hormone ( G n RH ) to dairy cows without a corpus luteum ( CL ) 4 weeks after calving can improve reproductive performance. Holstein dairy cows underwent ultrasonography to assess the presence of ovarian structures at 29.2 ± 5.2 days post‐partum, and cows were divided into two main groups based on the presence ( CL group, n = 230) or absence (non‐ CL group, n = 460) of a CL . The non‐ CL group was further randomly divided into two subgroups based on the administration of G n RH (non‐ CL G n RH group, n = 230) or no G n RH (non‐ CL control group, n = 230). Subsets of cows from non‐ CL control (n = 166) and non‐ CL Gn RH (n = 175) groups received a second ultrasonography at 44.5 ± 5.4 days post‐partum to assess CL formation. The percentage of cows with CL at the second ultrasonography was greater in the non‐ CL G n RH group (70.9%) than in the non‐ CL control group (53.0%, p = 0.0006). The hazard of the first post‐partum insemination by 150 days in milk ( DIM ) was higher in the CL group than in the non‐ CL control group (hazard ratio [ HR ]: 1.36, p = 0.001). The probability of a pregnancy to the first insemination was higher in non‐ CL Gn RH (odds ratio [ OR ]: 1.50, p = 0.04) and CL groups ( OR : 1.55, p = 0.03) compared to the non‐ CL control group. Furthermore, the hazard of pregnancy by 210 DIM was higher in non‐ CL G n RH ( HR : 1.30, p = 0.01) and CL ( HR : 1.51, p = 0.0001) groups than in the non‐ CL control group. In conclusion, administration of G n RH to dairy cows without a CL 4 weeks after calving was associated with an increase in ovulation and improved reproductive performance.