Maize seed germination inhibition test for pregnancy diagnosis in Zebu cows

Résumé

Pregnancy diagnosis is an important part of good management and helps to maximize
reproductive performance. Over time, different methods for detection of pregnancy in cows and other female domestic animals have been developed which include observation, physical examination, chemical tests and electronic instruments. Seed germination inhibition technique was carried out to detect pregnancy in Zebu cows. The urine samples collected from four pregnant cows, four non pregnant cows, four bulls and water (control) were subjected to seed germination test using maize seeds. Urine was collected between 5 and 7 am. Pregnant cows were confirmed by rectal palpation. The pH of the urine samples was determined before and after dilution and consequently, the urea concentration was also analyzed in the laboratory. The urine was diluted at the ratio of 1:4 with distilled water. Control test was also carried out with the addition of water only to the maize seeds. In each sterile Petri dish fifteen maize seeds were taken on the filter paper and 15mL of diluted urine was added. The seed germination inhibition percentages were observed after five days while shoot length growth inhibition was also observed after five days. Germination inhibition percentage of pregnant cows (64.16%) was significantly (P<0.05) higher compared to nonpregnant cows (34.18%), bull urine and water control. Shoot length of seeds germinated with distilled water had the highest value (4.38cm), seeds germinated with bull urine and non pregnant cow urine showed similarities while seeds germinated with pregnant cow urine had the least value (1.37cm) across the observations for shoot length growth inhibition. The result on pH showed clear differences in the pH of urine from pregnant (8.11- 8.25), non pregnant cows (6.05-7.04) and bull urine (6.35-7.34). The pH of the urine samples for nonpregnant cow and bull urine samples were similar to that of the control. Urea concentration of pregnant cow urine (11.06 mg/dL) was higher than that observed in bull urine 4.56 mg/dL and non pregnant cow urine 1.39 mg/dL. The study was able to validate that at 60% and above inhibition there is an indication of pregnancy while inhibition less than 60% shows the cow is non pregnant. Increased mean germination inhibition percentage and reduced shoot length in pregnant cow urine were indicative of pregnancy state.