Plasma progesterone, metabolic hormones and beta-hydroxybutyrate in Holstein-Friesian cows after superovulation.

Metabolic hormones [insulin, leptin, insulin-like growth factor-I (IGF-I), thyroxine (T4) and triiodothyronine (T3)], progesterone (P4) and beta-hydroxybutyrate (BHB) serum concentrations were evaluated and their effect on the superovulation results of donor cows was investigated in a semi-arid environment. Body weight, body condition score (BCS) and lactation stage were also included in the analysis. Twenty-three Holstein-Friesian cows were superovulated with 600 IU FSHp following the routine procedure and flushed on day 7 in a Multiple Ovulation and Embryo Transfer Centre in the semi-arid area of Brazil. The corpora lutea (CL) were counted and blood samples were collected for assays. All of the hormones investigated and BHB serum concentrations were within the physiological ranges. There was a positive correlation between hormones, except between BHB and all the others. The leptin level was influenced by feeding status, as indicated by the BCS. Insulin, T4, T3 and BHB levels were affected by milking status. Dry cows had higher levels of all hormones except BHB. An optimum level of leptin resulted in the highest number of CL, while the linear increase of P4, T4 and IGF significantly increased the number of CL.

Changes in embryo production results and ovarian recrudescence during the acclimatisation to the semiarid tropics of embryo donor Holstein-Friesian cows raised in a temperate climate.

Pregnant Holstein-Friesian (HF) heifers were transported from central Europe (defined as temperate conditions) to north-eastern Brazil (defined as tropical, semiarid conditions). They were kept in open-sided pens with a hard floor, a roof for shade and sprinkled with water for 10 min every hour if ambient temperature exceeded 30 degrees C. Their diet was balanced to meet nutritional requirements and they were fed twice daily. Control animals were randomly chosen first and second lactation animals located on a farm 25 km away and receiving similar management. Imported animals were superovulated in 1996 (n=63) and 1997 (n=96), compared to 38 and 45 cows in the control herd. The variates recorded were: the interval post-partum to first oestrus; changes in ovarian size and activity; responses to superovulation; and, embryo quality. The average daily milk yields of the imported cows were 20.0 and 23.3 l in 1996 and 1997, respectively compared to 22.1 l throughout the experiment for cows in the control herd. The post-partum anoestrus interval in the imported cows were 112.1+/-30.5 days in 1996 compared to 55.0+/-18.0, 48.2+/-12.0 and 42.6+/-10.7 days in 1997 for control cows. The size and functionality of the ovaries was lowest for the imported animals in 1996 but did not differ between other group-year combinations. These animals also had a lower superovulatory response in 1996 than control cows in terms of the number of ovulations (6.4+/-4.3 versus 13.6+/-5.9, P<0.05) and good quality embryos (1.2+/-0.9 versus 4.4+/-2.1, P<0.05). The two groups of cows did not differ in respect of these characters in the second year of the study. The imported cows had lower reproductive efficiency and responses to superovulation in their first year in their new environment. A period of approximately 1.5 years is required for full adaptation.