Relationships between insulin-like growth factor-I,milk yield,body condition score,and postpartum luteal activity in high-producing dairy cows |
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Authors: | Amin Tamadon Mojtaba Kafi Mehdi Saeb Abdolah Mirzaei Saedeh Saeb |
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Institution: | (1) Stem Cell and Transgenic Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran;(2) Department of Animal Health Management, School of Veterinary Medicine, Shiraz University, Shiraz, 71345, Iran;(3) Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran;(4) Department of Basic Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran |
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Abstract: | The relations between body condition score (BCS), milk yield, serum insulin-like growth factor-I (IGF-I) profile, and luteal
activity were investigated in postpartum dairy cows. Seventy-one healthy high-producing multiparous Holstein cows were subjected
to transrectal ultrasound scanning twice weekly from the first to the eighth week postpartum. Blood samples were collected
twice weekly to measure serum progesterone (P4) and every 2 weeks to detect serum IGF-I concentrations. BCS was monitored
weekly after calving. Cows with serum P4 concentrations ≥1 ng/ml on at least two consecutive samplings were considered to
have commenced luteal activity. Commencement of luteal activity (C-LA) was observed earlier than 45 days postpartum in 71.8%
of cows while 28.2% showed C-LA later than 45 days. Prolonged luteal phase was the most common abnormal pattern of luteal
activity observed. Cows with a C-LA earlier than 45 days postpartum had higher (P ≤ 0.05) mean serum concentrations of IGF-I than those with later C-LA. In addition, cows which showed C-LA earlier than 45 days
postpartum had more optimal productive indices including shorter calving to conception interval and calving to first service
interval (P ≤ 0.05), and fewer services per conception (P = 0.07). C-LA was significantly later in cows that lost more than 0.5 BCS units within 3 weeks postpartum than in those that
lost less than 0.5 units BCS during the same interval (P = 0.02). We conclude that high-producing dairy cows with higher postpartum serum IGF-I concentrations have earlier commencement
and normal luteal activity, and better reproductive performance. Severity and duration of BCS loss adversely affect commencement
of luteal activity. |
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