Hormonal and cytogenetic analyses of reproductive activity of cattle

The first part of the present study investigated abnormal ovarian cyclicity (AOC) and cystic ovarian diseases (COD) based on plasma progesterone (P4) profiles and ovarian ultrasonogram in 102 cattle which comprised cows open > 90 days postpartum and heifers with delayed age (>24 months) at first calving. Highest incidence of AOC associated with either COD or inactive ovaries occurred in Brangus (BR; 53.3%) and lowest incidence in Kedah Kelantan (KK) cows (12.5%). The difference in AOC was significant (P< 0.05) between KK and the other three breeds. In cows, incidence of COD was highest in FRS (30%), followed by BRF (13.3%), BR (14.3%) and KK (8.7%). Overall, incidence of COD was higher in beef heifers than in cows. Prolonged luteal phase due to luteal cysts was the predominant type of AOC in FRS (66.7%) while cessation of cyclicity due to follicular cysts was the main abnormality in BR (75%) and BRF (76.9%). Thus, this study showed AOC and COD as major causes of reproductive failure in dairy and beef cattle with KK cows being the least affected. Moreover, the combination of P4 data and ultrasonograms was able to differentiate the various types of COD. The study was extended to determine the bulls‟ fertility status. Breeding soundness evaluation (BSE) revealed 3 of the 8 bulls examined had testicle defects and/or poor semen quality. Testicular lesions included testicular degeneration, hydrocele and fibrotic foci. In addition, cytogenetic investigation on 20 animals (13 females and 7 bulls) showed normal cattle chromosome complement of 60 and confirmed the acrocentric Y in KK bulls as of zebu genotype. Thus, the study ruled out chromosomal aberration as a cause of reproductive failure. Measurement of faecal progestin levels to monitor reproductive activity in cattle was another aspect of the present study. Evaluation of modified faecal extraction protocol was 76.8% efficient to recover faecal progestins and hence subsequently used in this study. Matched plasma and faecal samples collected twice a week for 3 months, from cycling as well as pregnant KK and from Brangus cows with either regular cycle or ovarian disturbance, were assayed for plasma P4 and faecal progestin concentrations respectively, by RIA. There was a significant positive correlation (r= 0.6, P1 ng/ml in pregnant cows, coincided with faecal progestin of >344 ng/g. Hence, faecal progestin concentrations that remain >344 ng/g for >20 days indicate pregnancy in KK cows in the absence of ovarian and/or uterine disorders. In contrast, Brangus cows with ceased ovarian cycle had progestin concentrations of ≤344 ng/g, consistent with plasma P4 of ≤1 ng/ml. Mean concentration of faecal progestin was significantly (P